CN1773333A - Liquid crystal display device, its manufacturing method and its driving method - Google Patents

Abstract

Before starting the regular display in a liquid crystal display device of the bend alignment type, it is necessary to transition all the pixel regions in the entire display portion uniformly from splay alignment into bend alignment. However, conventionally, when applying a simple ac voltage, the transition sometimes does not take place, and when it does take place, the transition time is very long, and display defects due to alignment defects tend to occur. In the method for driving a liquid crystal display device with OCB cells according to the present invention, a step of applying between an electrode 22 and a pixel electrode 23 an ac voltage superimposed with a bias voltage, and a step of applying zero voltage or a low voltage to the substrates are repeated in alternation preceding the begin of the regular display operation and the regular display operation is carried out after all pixels have transitioned into bend alignment.

Description

Liquid crystal display device, its manufacturing method and its driving method

(This application is the divisional application of the application number 01137066.1 and the same invention title submitted on October 17, 2001.)

technical field

The present invention relates to an OCB mode liquid crystal display device of high-speed response and wide field of view for displaying television images, personal computers, and multimedia images, its manufacturing method, and its driving method.

Background technique

So far, as a liquid crystal display device, for example, as the liquid crystal display mode, although a twisted nematic (TN) mode liquid crystal display device using a nematic liquid crystal having a positive dielectric coefficient anisotropy has been put into practical use, it has a response Slow, narrow field of view and other shortcomings. In addition, although there are also display modes such as ferroelectric liquid crystal (FLC) or antiferroelectric liquid crystal with fast response and wide viewing angle, they are difficult to maintain in terms of display image retention, impact resistance, and temperature dependence of characteristics. There are big disadvantages. In addition, although there is an in-plane switching (IPS) mode in which the liquid crystal molecules are driven by an in-plane transverse electric field with an extremely wide viewing angle, the response speed is slow, the aperture ratio is low, and the luminance is low. If you want to display full-color animation on a large screen, a liquid crystal display mode with wide field of view, high brightness, and high-speed display performance is necessary, but a practical liquid crystal display mode that satisfies these requirements perfectly at the same time does not exist yet. .

In the past, as a liquid crystal display device aimed at at least a wide viewing field and high brightness, there are liquid crystal display devices (SID 92 DIGEST P798-801) that divide the above-mentioned TN mode liquid crystal region into two orientations and expand the viewing angle upward and downward. . That is, in each display pixel of a liquid crystal display device, a nematic liquid crystal with a positive dielectric anisotropy is used to form two liquid crystal regions in a TN mode and with different alignment orientations of the liquid crystal molecules, that is to say, two liquid crystal regions with different alignment orientations. A liquid crystal display device that subdivides the TN mode to expand the viewing angle.

FIG. 48 shows a schematic configuration diagram of this conventional liquid crystal display device. In Fig. 48, 701 and 702 are glass substrates, 703 and 704 are electrodes, and 705, 705', 706 and 706' are alignment films. In one alignment region A, the large and small pretilt angles of nematic liquid crystal molecules 707, 707' with positive dielectric anisotropy that slightly tilt the opposing upper and lower substrate interfaces are formed, and in the other region B, for The opposing upper and lower substrate interfaces set the pretilt angle opposite to that of the alignment region A described above. Pretilt angles of this size are all set with a difference of several degrees. As an example of the existing manufacturing method for forming alignment regions with different pretilt angles on the upper and lower substrates, a photoresist is coated on the alignment film, and it is masked by photolithography technology, and the alignment area is formed in a predetermined direction. A method of repeatedly polishing a desired alignment film surface. In the above configuration, as shown in FIG. 1 , in the alignment regions A and B, the orientations of the liquid crystal molecule groups in the center of the liquid crystal layer are mutually reversed. Standing upright, the angle of view is enlarged by averaging the anisotropy of the refractive index with respect to the incident light in units of pixels. In the above-mentioned conventional TN mode with double-division orientation, the field of view is expanded with the usual TN mode, and the up and down field of view will be about ±35 degrees based on a contrast ratio of 10.

However, the response speed is about 50ms, which is essentially the same as the TN mode. As described above, both the angle of view and the response are insufficient in the above-mentioned conventional double-divided orientation TN mode.

In addition, although it is useful to use the liquid crystal display mode of the so-called vertical alignment mode in which the liquid crystal molecules are aligned substantially vertically at the interface of the alignment film, a liquid crystal display device with a wide field of view and high-speed response is added with a thin-film phase difference plate and alignment segmentation technology. , but even this kind of liquid crystal display device takes about 25ms for the response speed between black and white binary values, especially the response speed between brightness levels is as slow as 50-80ms, which is about 25ms faster than the recognition speed of the human eye. 1/30th of a second is still long, and the animation looks like it's flowing.

In response to this, a bend alignment type liquid crystal display device (OCB mode liquid crystal display device) using a change in refractive index due to a change in the standing angle of liquid crystal molecules in a state of bend alignment of liquid crystal molecules between substrates has been proposed. . The alignment change speed of each liquid crystal molecule in the bend orientation in the ON state and the OFF state is much faster than the alignment change speed between the ON and OFF states of the TN type liquid crystal display device, and a liquid crystal with a fast response speed can be produced. display device. In addition, since the above-mentioned bend alignment type liquid crystal display device, the liquid crystal molecules are integrally bent and aligned between the upper and lower substrates, so the optical phase can be self-compensated, and since the phase compensation is performed by a thin-film phase difference plate, it has the advantage of being low-voltage wide Possibility of field of view liquid crystal display device.

However, the above-mentioned liquid crystal display device is usually produced after bringing liquid crystal molecules into a spray alignment state between substrates under no voltage. In order to change the refractive index by bend alignment, before starting to use the liquid crystal display device, it is necessary to uniformly transform the entire display portion from the above-mentioned splay alignment state to the bend alignment state. When a voltage is applied between the facing display electrodes, the places where the transition nuclei from the spray alignment to the bend alignment occur are not uniform around scattered spaces or alignment spots and defects at the interface of the alignment film. In addition, since the transition nucleus does not always occur from the above-mentioned constant location, display defects are likely to occur due to occurrence or non-occurrence of transition. Therefore, it is extremely important to shift the entire display portion, at least the entire pixel portion, from splay alignment to bend alignment before starting use.

However, in the past, even if a pure AC voltage is applied, transfer will not occur, and even if transfer occurs, the transfer time will be extremely long.

Contents of the invention

The object of the present invention is to provide a bend orientation method that can realize no display defects, fast response speed, suitable for moving image display, and wide field of view by substantially reliably generating bend orientation transfer and completing the transfer in an extremely short time. A liquid crystal display device, a manufacturing method and a driving method thereof.

In order to solve the above-mentioned problems, the invention according to the first aspect of the present invention is a driving method for performing orientation transition from splay alignment to bend alignment in a liquid crystal display device, the device comprising a pair of substrates and a liquid crystal layer interposed between the substrates, When no voltage is applied, the positive and negative pretilt angles of the liquid crystals at the upper and lower interfaces of the above-mentioned liquid crystal layer are opposite to each other, and become the spray alignment that has been oriented parallel to each other. Before the liquid crystal display is driven, by applying voltage to carry out the initialization process of transferring the alignment state of the above-mentioned liquid crystal layer from spray alignment to bend alignment, and to perform liquid crystal display driving in the bend alignment state that has been initialized, and it is characterized in that: an AC voltage superimposed on the bias voltage is added to Between the substrates, the liquid crystal layer is shifted into a bend alignment.

According to the method described above, the transfer time can be shortened by applying an AC voltage superimposed on the bias voltage between the above-mentioned substrates, compared with the case of simply applying an AC voltage. This is because the alignment of the liquid crystal molecules is fluctuated by the bias voltage due to the superposition of the bias voltages, and the liquid crystal molecules are shifted to one substrate side. With this, in the liquid crystal layer, transition nuclei are reliably generated in a short time, and the transition time is shortened. In addition, the transfer time can be further accelerated by means of an increase in the effective voltage.

The invention according to claim 2 is a method for driving alignment transition from spray alignment to bend alignment in a liquid crystal display device, the apparatus comprising a pair of substrates and a liquid crystal layer sandwiched between the substrates, and the liquid crystal layer The pretilt angles of the liquid crystals at the upper and lower interfaces are positive and negative, and become the spray alignment that has been oriented parallel to each other. Before the liquid crystal display is driven, the alignment state of the above-mentioned liquid crystal layer is carried out by applying a voltage between the above-mentioned substrates. The initializing process from the splay alignment to the bend alignment, and the driving of the liquid crystal display in the state of the initialized bend alignment, is characterized in that the AC voltage superimposed on the above bias voltage is alternately and repeatedly applied between the above-mentioned substrates. The process and the process of making the above-mentioned substrates into an electrically open state transfer the liquid crystal layer to a bend alignment.

As in the above configuration, by providing an electrically open state period after the application of the AC voltage, the orientation of the liquid crystal molecules in the liquid crystal layer is fluctuated by the bias voltage, causing the liquid crystal molecules to deviate to one substrate side. With this, in the liquid crystal layer, transition nuclei are reliably generated in a short time, and the transition time is shortened.

The invention according to claim 3 is a method for driving alignment transition from splay alignment to bend alignment in a liquid crystal display device, the apparatus comprising a pair of substrates and a liquid crystal layer sandwiched between the substrates, and the liquid crystal layer when no voltage is applied The pretilt angles of the liquid crystals at the upper and lower interfaces of the layer are positive and negative, and become the spray alignment that has been oriented parallel to each other. Before the liquid crystal display is driven, the above-mentioned liquid crystal layer is oriented by applying a voltage between the above-mentioned substrates. The initializing process of transitioning the state from the splay alignment to the bend alignment, and performing liquid crystal display driving in the state of the bend alignment after the initialization is performed, is characterized in that it is alternately and repeatedly applied to the above-mentioned substrate with an AC voltage superimposed on the bias voltage The process between and the process of applying 0 voltage or low voltage between the above-mentioned substrates will transfer the liquid crystal layer into a bend orientation.

As in the above configuration, by setting the AC voltage and during the 0-voltage or low-voltage period, the swing ratio of the liquid crystal molecular orientation of the liquid crystal layer will become larger than that of the invention described in the second aspect. Therefore, the phenomenon that the liquid crystal molecules are deflected to one side of the substrate will occur in an extremely short time, and by means of this, the transfer time can be further accelerated.

The invention according to claim 4 is characterized in that, in the method of driving a liquid crystal display device according to claim 3, a DC voltage is used instead of the AC voltage superimposed on the bias voltage.

Even if a DC voltage is applied instead of an AC voltage as in the above configuration, after the DC voltage is applied, there is a period of zero voltage or a low voltage, so as a result, the liquid crystal molecule orientation of the liquid crystal layer still fluctuates. . Therefore, even in such a driving method, the transition time can be shortened.

The invention according to claim 5 is characterized in that: in the driving method of the liquid crystal display device according to claim 2, the frequency of the alternately repeated voltage is in the range from 0.1 Hz to 100 Hz, and the above-mentioned alternately The duty cycle of the repeated voltage ranges from 1:1 to 1000:1.

Here, the term "voltage that alternately repeats" refers to a voltage when the alternating repetition between the AC voltage application period and the electrical open state period is regarded as a whole as one voltage waveform. The reason why the frequency and duty ratio of such alternately repeated voltages are limited is as follows.

If the frequency is lower than 0.1 Hz, since there is almost no repetition of reciprocation, there will be no phenomenon that the orientation of the liquid crystal molecules is biased to one side due to the repetition of reciprocation. On the other hand, if the frequency is higher than 100 Hz, the frequency of the repetition of the interaction is too high to be close to a direct current voltage, and the phenomenon that the alignment of the liquid crystal molecules due to the repetition of the interaction will not be biased to one side will not occur.

In addition, when the duty ratio is smaller than 1:1 (for example, 1:5, etc.), sufficient voltage cannot be applied to the liquid crystal layer. On the other hand, when the duty ratio is greater than 1000:1, it is close to a DC voltage with almost no alternating repetition, and the liquid crystal molecule alignment phenomenon due to the alternating repetition does not occur.

The invention according to claim 6 is characterized in that: in the method for driving a liquid crystal display device according to claim 3, the frequency of the alternately repeated voltage ranges from 0.1 Hz to 100 Hz, and the above-mentioned alternately The duty cycle of the repeated voltage ranges from 1:1 to 1000:1.

The reason for restricting the frequency and duty ratio of such alternately repeated voltages is the same as the reason for the above-mentioned fifth aspect.

The invention described in the seventh aspect is a driving method of an active matrix liquid crystal display device, which is characterized in that: in the driving method of the liquid crystal display device described in the first aspect, the above-mentioned AC voltage is applied to the Between the pixel electrodes of the active matrix liquid crystal display device on the switching device formed on one substrate and the common electrode formed on the other substrate.

According to the above configuration, the transition time can be shortened in an active matrix type liquid crystal display device.

The invention described in the eighth aspect is a driving method of an active matrix liquid crystal display device, which is characterized in that: in the driving method of the liquid crystal display device described in the third aspect, the above-mentioned AC voltage is applied to the Between the pixel electrodes of the active matrix liquid crystal display device on the switching device formed on one substrate and the common electrode formed on the other substrate.

According to the above configuration, the transition time can be shortened in an active matrix type liquid crystal display device.

The invention according to claim 9 is characterized in that, in the method of driving a liquid crystal display device according to claim 8, the AC voltage is applied to the common electrode.

With the above configuration, the transition time can also be shortened.

The invention described in claim 10 is a method for driving an active matrix liquid crystal display device, which is characterized in that: in the method for driving a liquid crystal display device described in claim 4, the AC voltage is applied to the Between the pixel electrodes of the active matrix liquid crystal display device on the switching device formed on one substrate and the common electrode formed on the other substrate.

According to the above configuration, the transition time can be shortened in an active matrix type liquid crystal display device.

The invention according to claim 11 is characterized in that, in the method of driving a liquid crystal display device according to claim 10, the AC voltage is applied to the common electrode.

With the above configuration, the transition time can also be shortened.

The invention according to claim 12 is characterized in that: in the method for driving a liquid crystal display device according to claim 1, the voltage value of the AC voltage is set so that the liquid crystal layer changes from a splay alignment state to a bend alignment state. The threshold voltage value of the minimum voltage value required for transfer.

With the configuration described above, lower voltage can be achieved.

The invention according to claim 13 is characterized in that: in the method for driving a liquid crystal display device according to claim 4, the voltage value of the DC voltage is set so that the liquid crystal layer changes from a splay alignment state to a bend alignment state. The threshold voltage value of the minimum voltage value required for transfer.

With the configuration described above, lower voltage can be achieved.

The invention according to claim 14 is characterized in that in the method of driving a liquid crystal display device according to claim 3, the voltage is a voltage that is averaged over time and alternated.

With the above configuration, deterioration of the liquid crystal can be prevented.

The invention according to claim 15 is a liquid crystal display device comprising a pair of substrates and a liquid crystal layer sandwiched between the substrates. When no voltage is applied, the pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer are mutually positive and negative. On the contrary, it becomes the splay alignment that has been oriented parallel to each other. Before the liquid crystal display is driven, an initialization process is performed to transfer the alignment state of the liquid crystal layer from the splay alignment to the bend alignment by applying a voltage between the above-mentioned substrates. The liquid crystal display is driven in the state of bend orientation after this initialization, and it is characterized in that: in order to transfer the above-mentioned liquid crystal layer from the spray alignment to the bend alignment, an AC voltage or a DC voltage superimposed on the bias voltage is applied between the above-mentioned substrates. voltage application device.

According to the above configuration, a liquid crystal display device having a short transition time can be realized.

The invention according to claim 16 is characterized in that: in the method for driving a liquid crystal display device according to claim 15, the voltage value of the AC voltage or the DC voltage is set so as to change the liquid crystal layer from the spray alignment state to The critical voltage value of the minimum voltage value required for the bend orientation state transition.

With the above configuration, a liquid crystal display device having a short transition time can be realized.

The invention described in claim 17 is an active-matrix liquid crystal display device at the pretilt angle of the liquid crystal at the upper and lower interfaces of the liquid crystal layer arranged between the array substrate with pixel electrodes and the opposite substrate with common electrodes. Positive and negative reciprocal, and have been carried out in parallel to each other in the liquid crystal cell of spray alignment, when no voltage is applied, it has become spray alignment, and before the liquid crystal display is driven, the alignment state of the above-mentioned liquid crystal layer is carried out by applying voltage The initializing treatment from the splay alignment to the bend alignment is carried out, and the liquid crystal display is driven in the state of the bend alignment after the initialization, and it is characterized in that: a liquid crystal unit is provided, and the liquid crystal unit has at least the above-mentioned array substrate in the same pixel. The pretilt angle of the liquid crystal in the alignment film formed on the inner surface side of the substrate represents the first pretilt angle, while the pretilt angle of the liquid crystal in the alignment film formed on the inner surface side of the opposite substrate represents the ratio of the first pretilt angle The first liquid crystal cell region with a larger second pretilt angle; and the pretilt angle of the liquid crystal produced by the alignment film formed adjacent to the first liquid crystal cell region and formed on the inner surface side of the array substrate represents the third pretilt angle. At the same time, the pretilt angle of the liquid crystal in the alignment film formed on the inner surface side of the opposite opposite substrate represents the second liquid crystal cell region of the 4th pretilt angle smaller than the third pretilt angle; The alignment process is from the first liquid crystal cell area to the second liquid crystal cell area; between the above-mentioned pixel electrode and the above-mentioned common electrode, a first voltage for forming disclination (disclination) lines is applied, and in the above-mentioned first liquid crystal cell A first voltage applying means for forming a disclination line near the boundary between the region and the second liquid crystal cell region; applying a second voltage higher than the first voltage between the pixel electrode and the common electrode The method is to generate a transition nucleus in the disclination line, and a second voltage application device is used to transfer from the spray alignment to the bend alignment.

Adopt the method of making above-mentioned structure, adopt the method that adds the first voltage between above-mentioned pixel electrode and common electrode, just can form distortion energy between the above-mentioned 1st liquid crystal cell region and the 2nd liquid crystal cell region than surrounding. high disclination line, in addition, by applying a second voltage higher than the first voltage between the above-mentioned pixel electrode and the above-mentioned common electrode, more energy is supplied to the above-mentioned disclination line, so that Misalignment shifts from spray alignment to bend alignment.

Therefore, in the liquid crystal display device configured as described above, the spray-bend alignment transition can be reliably generated in a constant place (disc line) in each pixel region in which a plurality of liquid crystal cells have been formed. The orientation transition can be reliably and rapidly generated without causing display defects, and thus a high-quality and inexpensive liquid crystal display device can be realized.

The invention according to claim 18 is characterized in that: in the liquid crystal display device according to claim 17, the first and fourth pretilt angles are 3 degrees or less, and the second and third pretilt angles are 4 degrees or less. above.

By adopting the above configuration, the ratio of the second and fourth pretilt angles to the first and third pretilt angles can be increased. By increasing the above ratio, disclination lines with higher distortion energy than the surrounding ones can be formed, and the transition time from spray alignment to bend alignment can be further shortened.

In the invention of claim 19, in the liquid crystal display device of claim 17, the orientation treatment direction of the alignment film is at right angles to the signal electrode lines or gate electrode lines along the pixel electrodes.

With the method of making the above-mentioned structure, since a transverse electric field is applied in a direction substantially perpendicular to the alignment state direction of the liquid crystal molecules in the liquid crystal layer from the transverse electric field applying portion, the liquid crystal molecules receive twisting force from the transverse electric field. Transition nuclei are generated in the disclination line, and the orientation transition from the spray orientation to the bend orientation can be rapidly performed.

The invention according to claim 20 is characterized in that: in the liquid crystal display device according to claim 17, the orientation treatment direction of the alignment film is at right angles to the signal electrode line or the gate electrode line along the pixel electrode. There are some deviations in direction.

By making the alignment treatment direction of the above-mentioned alignment film slightly deviate from the direction perpendicular to the signal electrode line or the gate electrode line along the above-mentioned pixel electrode, as a result, the signal from the signal electrode line is added obliquely to the above-mentioned disclination line. The transverse electric field of the electrode lines or the gate electrode lines results in a twisting force applied to the liquid crystal molecules in the spray alignment, so that the transition to the bend alignment becomes easier.

The invention according to claim 21 is characterized in that: in the liquid crystal display device according to claim 17, the frequency of the second voltage is in the range from 0.1 Hz to 100 Hz, and the duty ratio of the second voltage is At least a pulse-like voltage ranging from 1:1 to 1000:1.

By applying the pulse-shaped second voltage as described above, and repeating alternately the period of voltage application and the period of no voltage application, the shaking liquid crystal molecules become a state that is easy to transfer, so the liquid crystal molecules of the spray alignment are bent toward Orientation transfer. In addition, the reason why the above-mentioned frequency and duty ratio are limited to the above-mentioned range is to expand the transition region from splay alignment to bend alignment.

In the invention according to claim 22, in the liquid crystal display device according to claim 17, the gate electrode lines are in an ON state during at least most of the periods during which the transition is performed.

The energy of the distortion in the disclination line region becomes higher than that in the surrounding area. In this state, as a result, a lateral electric field is applied to the disclination line from the gate electrode line arranged in the lateral direction of the pixel electrode. Large energies result in a rapid transition from splay orientation to bend orientation.

The invention according to claim 23 is characterized in that: in the liquid crystal display device according to claim 17, at least one of the alignment films formed on the inner side of the pixel electrode and the common electrode is provided. A part of the area is irradiated with ultraviolet rays, and the pretilt angle of the liquid crystal in the alignment film is changed to perform alignment division of the liquid crystal cell.

By irradiating ultraviolet light to a part of the alignment film, the surface of the alignment film in the area irradiated by ultraviolet light can be modified, and the pretilt angle of the liquid crystal in the modified alignment film can be reduced to a small value. In addition, the reason why the pretilt angle of the liquid crystal in the alignment film is reduced by the irradiation of ultraviolet rays is not clear yet, but it is considered that the side chains present on the surface of the alignment film are cut by ultraviolet rays. As described above, an alignment-segmented liquid crystal cell can be easily formed by irradiation with ultraviolet rays.

The invention according to claim 24 is characterized in that: in the liquid crystal display device according to claim 17, ultraviolet rays are irradiated to a part of the pixel electrode and the common electrode in an ozone atmosphere, so that the pixel electrode After planarizing a part of at least one of the electrodes within the common electrode and the common electrode, the alignment film is coated and sintered on the above-mentioned pixel electrode and the common electrode, and the pretilt angle of the liquid crystal in the above-mentioned alignment film is changed. Alignment split liquid crystal cell.

The surface of the pixel electrode and the common electrode can be flattened by irradiating ultraviolet rays to the above-mentioned pixel electrode and a part of the above-mentioned common electrode under an ozone atmosphere. In this way, the pretilt angle of the liquid crystal in the alignment film can be changed, and an alignment-segmented liquid crystal cell can be easily formed.

The invention described in claim 25 is a method of manufacturing an active-matrix liquid crystal display device. The pretilt angle is positive and negative reciprocally, and in the liquid crystal cell of spray alignment that has been oriented parallel to each other, it has become spray alignment when no voltage is applied. Before the liquid crystal display is driven, the above liquid crystal layer is made by applying voltage The alignment state is transferred from the spray alignment to the initialization process of the bend alignment, and the liquid crystal display is driven under the initialized bend alignment state. It is characterized in that it has the following steps: preparing and disposing on the array substrate with the pixel The pretilt angle of the liquid crystal at the upper and lower interfaces of the liquid crystal layer between the opposite substrates of the electrodes is positive and negative reciprocal reciprocal, and the preparation process of the liquid crystal unit of the spray alignment that has carried out the alignment treatment in parallel; between the above-mentioned pixel electrode and the above-mentioned common electrode Between, add the 1st voltage that is used for forming disclination line, the disclination line formation process that forms the disclination line region near the boundary between the 1st liquid crystal cell region and the 2nd liquid crystal cell region; Give above-mentioned pixel A second voltage higher than the first voltage is applied between the electrode and the above-mentioned common electrode, so that a transfer nucleus occurs in the disclination line near the boundary between the first liquid crystal cell region and the second liquid crystal cell region, and the spray alignment Orientation transfer process to bend orientation.

By making the above-mentioned method, in the above-mentioned liquid crystal display device, in each pixel area where a plurality of liquid crystal cells have been formed, the spray-bend alignment transition can be reliably generated at a constant place (near the disclination line), In addition, since the energy of the distortion near the disclination line is higher than that around the disclination line, transfer nuclei are surely generated. Therefore, it is possible to reliably and quickly cause orientation transition without causing display defects, and thus it is possible to obtain a high-quality and inexpensive liquid crystal display device.

The invention according to claim 26 is characterized in that: in the method of manufacturing a liquid crystal display device according to claim 25, the preparation step includes a step of performing alignment treatment in a part of a pixel region, Make the pretilt angle of the liquid crystal on the side of the pixel electrode smaller than the pretilt angle of the liquid crystal on the side of the common electrode, and make the liquid crystal molecules carry out b-spray alignment, and in the other area of the above-mentioned one pixel , performing alignment treatment so that the pretilt angle of the liquid crystal on the pixel electrode side becomes larger than the pretilt angle of the liquid crystal on the common electrode side, and the liquid crystal molecules are subjected to t-spray alignment.

By making the above method, a b-spray alignment region and a t-spray alignment region can be formed in a pixel, and disclination lines can be clearly formed at their boundaries. In the vicinity of the disclination line, as described above, since the distortion energy is higher than that in the surrounding area, transfer nuclei are reliably generated. Therefore, orientation transition can be reliably and rapidly produced.

The invention according to claim 27 is characterized in that: in the method of manufacturing a liquid crystal display device according to claim 26, in the alignment treatment step, the inner surface of at least one electrode among the pixel electrode and the common electrode is A part of the alignment film formed on one side is irradiated with ultraviolet rays to change the pretilt angle of the liquid crystal to perform alignment division.

By irradiating ultraviolet light to a part of the alignment film, the surface of the alignment film in the area irradiated by ultraviolet light can be modified, and the pretilt angle of the liquid crystal in the modified alignment film can be reduced to a small value.

The invention according to claim 28 is characterized in that in the method of manufacturing a liquid crystal display device according to claim 26, in the alignment treatment step, at least one of the pixel electrode and the common electrode is placed under an ozone atmosphere. A part of the electrode is irradiated with ultraviolet rays, and after the surface of the pixel electrode and a part of the common electrode is planarized, the alignment film is coated and sintered on the above-mentioned pixel electrode and the common electrode, so that the liquid crystal in the alignment film is pre-planarized. Orientation segmentation is performed by changing the tilt angle.

By making the above method, the surface of the pixel electrode and the common electrode can be flattened. Therefore, by applying an alignment film to the pixel electrode and the common electrode, the pre-tilt of the liquid crystal in the alignment film can be made By changing the angle, a liquid crystal display device with alignment-segmented liquid crystal cells can be obtained.

The invention described in claim 29 is an active matrix liquid crystal display device, in which the positive and negative pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer between the array substrate and the opposite substrate are mutually reversed, and have been mutually reversed. In the liquid crystal cell of the spray alignment which is parallel to the alignment process, the spray alignment has been achieved when no voltage is applied. Before the liquid crystal display is driven, the initialization process of transferring the alignment state of the above-mentioned liquid crystal layer from the spray alignment to the bend alignment is performed by applying a voltage. Carrying out liquid crystal display driving under the bend alignment state of this initialization, it is characterized in that: in a pixel, at least one lateral electric field application part for transfer excitation is provided, and while the lateral electric field is generated by the lateral electric field application part, Continuously or intermittently apply voltage between the pixel electrode and the common electrode, so that each pixel has a transfer nucleus, and the entire pixel is transferred from the spray orientation to the bend orientation.

According to the above configuration, the following effects can be achieved.

While applying a voltage larger than the transfer voltage between the pixel electrode and the common electrode, at least one lateral electric field applying part for transfer excitation provided in a pixel applies a lateral electric field to the liquid crystal layer, by means of which, This lateral electric field application portion will become the starting point for the transfer of the liquid crystal layer from the spray alignment to the bend alignment (that is, the transfer nucleus can be reliably generated in the liquid crystal layer around the lateral electric field application portion), so that the transition from the spray alignment to the bend alignment can be performed rapidly. The orientation shift of the bend orientation.

The invention according to claim 30 is characterized in that in the liquid crystal display device according to claim 29, the direction of the lateral electric field generated by the lateral electric field applying portion is substantially perpendicular to the orientation treatment direction.

With the method of making the above-mentioned structure, since a transverse electric field is applied from the transverse electric field applying part to the orientation state direction of the liquid crystal molecules in the liquid crystal layer in a direction substantially vertically intersecting, the liquid crystal molecules will receive twisting force from the transverse electric field, so Transition nuclei are generated, and the orientation transition from the splay orientation to the bend orientation proceeds rapidly.

The invention according to claim 31 is characterized in that in the liquid crystal display device according to claim 29, the lateral electric field applying portion is deformed so that the peripheral portion of the pixel electrode is concavo-convex in a plane parallel to the substrate surface. The electrode deformation part.

According to the above constitution, the following effects are obtained.

As a result, the electric field concentrates on the lateral electric field application portion composed of the electrode deformed portion in which the periphery of the pixel electrode is deformed unevenly in a plane parallel to the substrate surface, and the signal electrode lines or lines that exist on the side of the lateral electric field application portion. Between the gate electrode lines, therefore, the lateral electric field generated in this case is stronger than the lateral electric field generated between the pixel electrode having no lateral electric field application portion and the signal electrode line or the gate electrode line. Therefore, transition nuclei can be reliably generated in the liquid crystal layer by the transverse electric field generated by the existence of the transverse electric field applying portion, and alignment transition from splay alignment to bend alignment can be rapidly performed.

The invention according to claim 32 is characterized in that in the liquid crystal display device according to claim 29, the lateral electric field applying portion deforms the peripheral portion of the pixel electrode in a plane parallel to the substrate surface so as to be uneven. The deformed part of the electrode wire.

According to the above constitution, the following effects are obtained.

The same function as that of the invention of claim 31 can be realized by the presence of the electrode wire deformation portion of either one or both of the electrode wires.

The invention according to claim 33 is characterized in that in the liquid crystal display device according to claim 29, the lateral electric field applying portion is deformed so that the peripheral portion of the pixel electrode is uneven in a plane parallel to the substrate surface. , and an electrode and an electrode line deformation portion that deform the signal electrode line or the gate electrode line in a concave-convex manner corresponding to the unevenness.

According to the above constitution, the following effects are obtained.

By making at least one side of the pixel electrode deform in a concave-convex manner in a plane parallel to the substrate surface, correspondingly, the signal electrode line or the gate electrode line or both are concave-convex. The deformed electrode and the transverse electric field applying portion of the deformed portion of the electrode wire can function in the same way as the thirty-first invention.

The invention according to claim 34 is characterized in that in the liquid crystal display device according to claim 29, the lateral electric field applying part is deformed by a wire for applying a lateral electric field which is deformed in a concave-convex manner in a plane parallel to the substrate surface. The horizontal electric field applying line is arranged in the same direction on the upper or lower layer of at least one of the signal electrode line or the gate electrode line with an insulating film interposed therebetween, and is connected to the signal electrode line or the gate electrode line. The drive circuit connected by the line.

According to the method of making the above structure, the above-mentioned transverse electric field applying line is a line dedicated to transverse electric field application, and since the insulating film is interposed in the transverse electric field applying line, it is arranged on at least one of the signal electrode line or the gate electrode line. or on the lower layer, so there is flexibility in continuously forming shapes such as concavities and convexities on the side of the lateral electric field application line. In addition, since the lines for applying a lateral electric field overlap the signal electrode lines or the gate electrode lines, there is little light absorption, so that the aperture ratio of the pixel does not decrease. Therefore, it is possible to create a redundant design with a degree of freedom in design.

The invention according to claim 35 is characterized in that in the liquid crystal display device according to claim 34, the transverse electric field applying line is disconnected from the drive circuit during normal liquid crystal display after orientation transition.

With the method of making the above-mentioned structure, since the above-mentioned transverse electric field applying lines are disconnected from the drive circuit during normal liquid crystal display after orientation transfer, in this case, the transverse electric field applying lines formed on the transverse electric field applying lines will be disconnected. A lateral electric field does not occur between the electric field applying portion and the pixel electrode. Therefore, in a normal liquid crystal display, the liquid crystal display does not suffer from disordered alignment, and a liquid crystal display device exhibiting a good liquid crystal display state can be obtained.

The invention according to claim 36 is an active matrix liquid crystal display device, in which the positive and negative pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer between the array substrate and the opposite substrate are mutually reversed, and are mutually reversed. In the liquid crystal cell of the spray alignment which is parallel to the alignment process, the spray alignment has been achieved when no voltage is applied. Before the liquid crystal display is driven, the initialization process of transferring the alignment state of the above-mentioned liquid crystal layer from the spray alignment to the bend alignment is performed by applying a voltage. , in which the liquid crystal display is driven in the bend alignment state in which the initialization is performed, it is characterized in that: in one pixel, in order to apply a transverse electric field for transfer excitation, there is a pixel electrode or a common pixel electrode in which a defective portion is formed at least one place. at least one of the electrodes.

According to the above constitution, the following effects are obtained.

Since there is at least one of the pixel electrode or the common electrode in which a defective portion is formed in at least one place in order to apply a lateral electric field for transfer excitation in a pixel unit, deformation of the electric field (oblique electric field) occurs. Therefore, the liquid crystal molecules are subjected to twisting force due to the oblique electric field, and transfer nuclei are reliably generated to accelerate the transition from the spray alignment to the bend alignment.

The invention according to claim 37 is an active matrix liquid crystal display device, in which the positive and negative pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer between the array substrate and the opposite substrate are mutually reversed, and have been mutually reversed. In the liquid crystal cell of the spray alignment which is parallel to the alignment process, the spray alignment has been achieved when no voltage is applied. Before the liquid crystal display is driven, the initialization process of transferring the alignment state of the above-mentioned liquid crystal layer from the spray alignment to the bend alignment is performed by applying a voltage. , in which the liquid crystal display is driven in the bend alignment state in which the initialization is carried out, it is characterized in that: in one pixel, there is a transverse electric field applying part for transfer excitation, and in addition, the one pixel has a part of the pixel electrode area The pretilt angle of the liquid crystal molecules represents the first pretilt angle, and the pretilt angle of the liquid crystal molecules in a part of the common electrode facing the pixel electrode is larger than the first pretilt angle. The pretilt angle of the liquid crystal molecules in the liquid crystal cell region and other regions of the above-mentioned pixel represents the third pretilt angle, and the pretilt angle of the liquid crystal molecules in another part of the common electrode facing the pixel electrode is greater than the third pretilt angle. The second liquid crystal cell region of the fourth pretilt angle with a still smaller tilt angle.

According to the above constitution, the following effects are obtained.

Since the effect of the transverse electric field application part is different from the pretilt angle in the above-mentioned first alignment region and the second alignment region, disclination lines will occur between the first and second alignment regions, which will become the starting point of orientation transfer, The transfer from splay orientation to bend orientation will be facilitated.

The invention according to claim 38 is characterized in that: in the liquid crystal display device according to claim 29, the frequency between the common electrode and the pixel electrode is in the range from 0.1 Hz to 100 Hz, and , a pulse voltage application portion of a pulse-shaped voltage having a duty ratio of at least a range from 1:1 to 1000:1.

The reason why the frequency and duty ratio of the pulse voltage application part are also limited to the above ranges is that there are some differences depending on the size and shape of the pixel, the thickness of the liquid crystal layer, etc., because it is necessary to expand the range from spray alignment to bend alignment Transferred for the sake of the transfer area.

By applying the above-mentioned pulse-like second voltage, and repeating alternately the voltage application period and the no voltage application period, the liquid crystal molecules will be in a state that is easy to transfer due to shaking, so the liquid crystal molecules in the spray alignment will be in the bend alignment state. transfer. In addition, the reason why the above-mentioned frequency and duty ratio are limited to the above-mentioned range is to expand the transition region from splay alignment to bend alignment.

The invention according to claim 39 is an active matrix liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates and a phase compensator arranged outside the substrates, wherein the above-mentioned The pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer are positive and negative, and have become spray alignments that have been oriented parallel to each other. Before the liquid crystal display is driven, the alignment state of the liquid crystal layer is changed from Spray alignment is transferred to the initialization process of bend alignment, and liquid crystal display driving is carried out in the state of bend alignment in which the initialization has been carried out. It is characterized in that: at least one place in the display pixel has a region where the thickness of the liquid crystal layer is smaller than that of the surrounding area, and The electric field strength applied to the liquid crystal layer in the above region is greater than the electric field strength applied to the surrounding liquid crystal layer.

According to the above constitution, transition nuclei are easily generated in the portion where the electric field intensity is high, and thus the transition time can be shortened.

The invention according to claim 40 is an active matrix liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates and a phase compensator arranged outside the substrates, wherein the above-mentioned The pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer are positive and negative, and have become spray alignments that have been oriented parallel to each other. Before the liquid crystal display is driven, the alignment state of the liquid crystal layer is changed from spray alignment to Transfer to the initialization process of the bend alignment, and carry out the liquid crystal display driving under the state of the bend alignment that has carried out this initialization, it is characterized in that: at least one place outside the display pixel has a region where the thickness of the liquid crystal layer is smaller than the surrounding area, and is added to the The electric field intensity on the liquid crystal layer in the above region is greater than the electric field intensity applied to the surrounding liquid crystal layer.

If the above configuration is adopted, electric field concentration occurs outside the pixel, and the transfer nuclei generated outside the pixel propagate into the pixel. Therefore, even in such a case, the transition time can be shortened.

The invention according to claim 41 is an active matrix liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates and a phase compensation plate arranged outside the substrates, wherein the above-mentioned The pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer are positive and negative, and have become spray alignments that have been oriented parallel to each other. Before the liquid crystal display is driven, the alignment state of the liquid crystal layer is changed from spray alignment to Moving to the initialization process of the bend alignment, the liquid crystal display is driven in the state of the bend alignment where the initialization has been carried out, and it is characterized in that there is an electric field concentrated portion in at least one place in the display pixel.

In addition, the invention according to claim 42 is characterized in that: in the liquid crystal display device according to claim 41, the above-mentioned electric field concentration part provided in the display pixel protrudes partially in the thickness direction of the liquid crystal layer. A part of the display electrode or the common electrode or both of them.

By adopting the display electrode structure as described above, it is possible to form the electric field concentrated portion.

In addition, the invention according to claim 43 is an active matrix liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates and a phase compensating plate arranged outside the substrates, and when no voltage is applied, At this time, the pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer are positive and negative, and the spray alignment has been carried out parallel to each other. Before the liquid crystal display is driven, the alignment state of the liquid crystal layer is changed from The initializing process of transferring the splay alignment to the bend alignment, and driving the liquid crystal display in the state of the initialized bend alignment is characterized in that there is an electric field concentrated portion at least one place outside the display pixel.

With the above configuration, by providing the electric field concentration portion outside the pixel as described above, the transition nuclei generated outside the pixel propagate into the pixel. Therefore, even in such a case, the transition time can be shortened.

Furthermore, in the invention according to claim 44, in the liquid crystal display device according to claim 43, the electric field concentration portion is a part of an electrode partially protruding in the thickness direction of the liquid crystal layer.

In addition, the invention according to claim 45 is an active matrix liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates and a phase compensating plate arranged outside the substrates, and when no voltage is applied, At this time, the pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer are positive and negative, and the spray alignment has been carried out parallel to each other. Before the liquid crystal display is driven, the alignment state of the liquid crystal layer is changed from The initializing process of shifting the splay alignment to the bend alignment, and driving the liquid crystal display in the initialized bend alignment state, is characterized by having openings in a part of the display electrode or the common electrode or both of them.

According to the above configuration, the transfer time can be shortened.

In addition, the invention according to claim 46 is characterized in that in the liquid crystal display device according to claim 45, the opening is formed on the planarization film of an active matrix liquid crystal display device having a switching device. Display electrodes and conduction ports electrically connected to the switching device.

According to the above configuration, the transfer time can be shortened.

In addition, the invention according to claim 47 is characterized in that: in the liquid crystal display device according to claim 39, the phase compensator plate includes at least one optical medium with negative refractive index anisotropy in which the main axes are mixed. phase compensation board.

Furthermore, the invention according to claim 48 is characterized in that in the liquid crystal display device according to claim 47, the phase compensation plate includes at least one positive phase compensation plate.

The invention according to claim 49 is a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other to transfer the alignment of the liquid crystal to a bend alignment, and it is characterized in that: The ejection elastic coefficient k11 of the liquid crystal is in the range of 10×10 ^-7 dyn ≥ k11 ≥ 6×10 ^-7 dyn, and assuming that the absolute value of the pretilt angle of the liquid crystal relative to the first substrate is θ1, the liquid crystal relative to the first substrate is 2 When the absolute value of the pretilt angle of the substrate is θ2, the relationship of 1.57rad>|θ1-θ2|≥0.0002rad is satisfied.

By making such a structure, the critical electric field for liquid crystal transition can be reduced, and the alignment state of liquid crystal molecules can be rapidly transferred from the initial state to the bend alignment.

The invention according to claim 50 is a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other to transfer the orientation of the liquid crystal to a bend orientation, and it is characterized in that: The ejection elastic coefficient k11 of the liquid crystal is in the range of 10×10 ^-7 dyn≥k11≥6×10 ^-7 dyn, and the above-mentioned electric field is superimposed on the sub-electric field applied uniformly in space. The electric field on the main electric field satisfies the relationship of 1.0>E1/E0>1/100 when the above-mentioned main electric field is E0 and the above-mentioned sub-electric field is E1.

With such a configuration, the critical electric field for liquid crystal transition can be reduced, and the alignment state of the liquid crystal molecules can be rapidly transferred from the initial state to the bend alignment.

The invention according to claim 51 is a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other to transfer the orientation of the liquid crystal to a bend orientation, characterized in that: When the absolute value of the pretilt angle of the liquid crystal to the above-mentioned first substrate is θ1, and the absolute value of the pretilt angle of the above-mentioned liquid crystal to the above-mentioned second substrate is θ2, the relationship of 1.57rad>|θ1-θ2|≥0.0002rad is satisfied, and , assuming that the above-mentioned electric field is an electric field that superimposes the auxiliary electric field that is applied unevenly in space on the main electric field that is applied uniformly in space, when the above-mentioned main electric field is E0, and the above-mentioned auxiliary electric field is E1, it satisfies 1.0>E1 The relationship of /E0>1/100.

With such a configuration, the critical electric field for liquid crystal transition can be reduced, and the alignment state of the liquid crystal molecules can be rapidly transferred from the initial state to the bend alignment.

The invention according to claim 52 is a method of applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other to transfer the orientation of the liquid crystal to a bend orientation, and it is characterized in that: The ejection elastic coefficient k11 of the liquid crystal is in the range of 10×10 ^-7 dyn ≥ k11 ≥ 6×10 ^-7 dyn, and assuming that the absolute value of the pretilt angle of the liquid crystal relative to the first substrate is θ1, the liquid crystal relative to the first substrate is 2 When the absolute value of the pretilt angle of the substrate is θ2, it satisfies the relationship of 1.57rad>|θ1-θ2|≥0.0002rad, and the above-mentioned electric field is superimposed on the spatially uniform secondary electric field The electric field on the main electric field applied on the ground satisfies the relationship of 1.0>E1/E0>1/100 when the above-mentioned main electric field is E0 and the above-mentioned sub-electric field is E1.

With such a configuration, the critical electric field for liquid crystal transition can be reduced, and the alignment state of the liquid crystal molecules can be rapidly transferred from the initial state to the bend alignment.

In addition, the above-mentioned pretilt angle is the orientation angle before the application of the electric field of the liquid crystal molecules connected to the surface of each substrate, and is the inclination of the molecular axis of the liquid crystal molecules connected to the surface of the substrate to a plane parallel to the substrate. An angle expressed in the range of -π/2 to π/2rad is based on the plane (=0) and counterclockwise rotation is positive. In addition, the pretilt angle of the liquid crystal relative to the first substrate and the pretilt angle of the liquid crystal relative to the second substrate are angles having different signs from each other.

In addition, the invention according to claim 53 is characterized in that in the method for driving a liquid crystal display device according to claim 50, the sub electric field is applied to the source of the thin film transistor formed on the surface of the first substrate. electrode or gate electrode, and the electric field between the transparent electrode formed on the surface of the above-mentioned second substrate.

Furthermore, the invention according to claim 54 is characterized in that in the method of driving a liquid crystal display device according to claim 50, the sub electric field is an AC electric field that decays with time.

Description of drawings

FIG. 1 is a perspective view showing a part of a liquid crystal display device including a bend-aligned OCB.

Fig. 2 is a cross-sectional view of a liquid crystal cell illustrating a transition from splay alignment to bend alignment.

3 is a schematic diagram showing the configuration of a pixel unit in a method of driving a liquid crystal display device according to Embodiment 1 of the present invention.

Fig. 4 is a waveform diagram of a voltage for orientation transfer used in Embodiment 1 of the present invention.

Fig. 5 is a graph showing the relationship between bias voltage and transition time in Embodiment 1 of the present invention.

6 is a schematic diagram showing the configuration of a pixel unit in a method of driving a liquid crystal display device according to Embodiment 2 of the present invention.

Fig. 7 is a waveform diagram of a voltage for orientation transfer used in Embodiment 2 of the present invention.

Fig. 8 is a graph showing the relationship between bias voltage and transition time in Embodiment 2 of the present invention.

9 is a schematic diagram showing the configuration of a pixel unit in a method of driving a liquid crystal display device according to Embodiment 3 of the present invention.

Fig. 10 is a waveform diagram of a voltage for orientation transfer used in Embodiment 3 of the present invention.

Fig. 11 is a graph showing the relationship between bias voltage and transition time in Embodiment 3 of the present invention.

12 is a schematic diagram showing the configuration of a pixel unit in a method of driving a liquid crystal display device according to Embodiment 4 of the present invention.

Fig. 13 is a waveform diagram of a typical driving voltage of a liquid crystal display device according to Embodiment 4 of the present invention.

Fig. 14 is a waveform diagram of a voltage for orientation transfer used in Embodiment 4 of the present invention.

Fig. 15 is a waveform diagram of a voltage for orientation transfer used in Embodiment 5 of the present invention.

Fig. 16 is a schematic sectional view of a liquid crystal display device according to Embodiment 7 of the present invention.

Fig. 17 is a schematic sectional view of a liquid crystal display device according to Embodiment 7 of the present invention.

FIG. 18 shows a method of manufacturing a liquid crystal display device according to Embodiment 7 of the present invention.

19 shows a liquid crystal display device according to Embodiment 8 of the present invention, FIG. 19( a ) is a schematic sectional view of the liquid crystal display device, and FIG. 19( b ) is a schematic plan view of the liquid crystal display device.

20 schematically shows the configuration of a liquid crystal display device according to Embodiment 9 of the present invention, FIG. 20(a) is a schematic sectional view of the liquid crystal display device, and FIG. 20(b) is a schematic plan view of the liquid crystal display device.

FIG. 21 also schematically shows the configuration of a liquid crystal display device according to Embodiment 9 of the present invention.

FIG. 22 shows another example of a liquid crystal display device according to Embodiment 9 of the present invention.

Figure 23 schematically shows the structure of a liquid crystal display device according to Embodiment 10 of the present invention, Figure 23 (a) is a schematic sectional view of a liquid crystal display device, Figure 23 (b) is a schematic plan view of a liquid crystal display device, Figure 23 (c) is a schematic cross-sectional view of a liquid crystal display device of another example.

Fig. 24 schematically shows the configuration of a liquid crystal display device according to Embodiment 11 of the present invention, Fig. 24(a) is a schematic plan view of the liquid crystal display device, and Fig. 24(b) is a schematic diagram showing electric field distortion.

25 schematically shows the structure of a liquid crystal display device according to Embodiment 12 of the present invention, FIG. 25(a) is a schematic sectional view of the liquid crystal display device, and FIG. 25(b) is a schematic plan view of the liquid crystal display device.

Fig. 26 schematically shows the configuration of a liquid crystal display device according to Embodiment 13 of the present invention.

27 is an explanatory diagram for explaining a manufacturing process of protrusions formed on the glass substrates of Embodiments 13 and 14 of the liquid crystal display device of Embodiment 13 of the present invention.

Fig. 28 is an explanatory view for explaining the manufacturing process of the protrusion following Fig. 27 of the present invention.

Fig. 29 shows the rubbing direction of the substrate used in Embodiment 13 of the present invention.

Fig. 30 is an external view showing the structure of the fourteenth embodiment.

Fig. 31 is a plan view of Embodiment 14.

Fig. 32 is an external view showing the configuration of a test cell used in the study of the spray-bend transition time of the liquid crystal display device according to Embodiment 15 of the present invention.

Fig. 33 is an explanatory view for explaining a manufacturing process of protrusions in a liquid crystal display device according to Embodiment 15 of the present invention.

Fig. 34 schematically shows the configuration of a liquid crystal display device according to Embodiment 16 of the present invention.

Fig. 35 schematically shows a pattern of a transparent electrode used in a liquid crystal display device according to Embodiment 16 of the present invention.

Fig. 36 is a sectional view of essential parts of a liquid crystal display device according to Embodiment 17.

Fig. 37 is a partially enlarged view of Fig. 36 .

Fig. 38 is a sectional view of essential parts of a liquid crystal display device according to an eighteenth embodiment.

FIG. 39 is an explanatory diagram for explaining the arrangement of optical devices in a liquid crystal cell used in the liquid crystal display device of Embodiment 18. FIG.

FIG. 40 shows voltage-transmittance characteristics of a liquid crystal cell used in the liquid crystal display device of Embodiment 18. FIG.

The schematic diagram of FIG. 41( a ) shows a uniform orientation, and the schematic diagram of FIG. 41( b ) shows a bend orientation.

Figure 42 shows the director of the liquid crystal layer.

Figure 43 shows the CR equivalent circuit.

FIG. 44 shows temporal changes in the orientation angle (θj) of liquid crystals under an external electric field that increases with time.

Fig. 45 shows the relationship between the ejection elastic coefficient (k11) and the critical electric field (Ec).

FIG. 46 shows the relationship between the difference in absolute value of the pretilt angle (Δθ) and the critical electric field (Ec).

FIG. 47 shows the relationship between the non-uniformity of the electric field (E1/E0) and the critical electric field (Ec).

Fig. 48 is a sectional view of a conventional example.

Implement the preferred scheme of the present invention

The present invention is based on a transition mechanism from splay alignment to bend alignment described below in a liquid crystal display device including a bend alignment type OCB cell. Therefore, first, after explaining the transfer mechanism in detail, the specific contents of the present invention will be described using the embodiments.

FIG. 1 is a perspective view showing a part of a liquid crystal display device including a bend alignment type OCB cell. The configuration of a liquid crystal display device including a bend alignment type OCB cell will be briefly described with reference to FIG. 1 . Between the substrates 10 and 11 arranged parallel to each other, a liquid crystal layer 13 containing liquid crystal molecules 12 is interposed. Although not shown, display electrodes for applying an electric field to the liquid crystal layer 13 and alignment films for restricting the alignment of liquid crystal molecules are formed on the surfaces of the substrates 10, 11 facing each other. As shown in the figure, the above-mentioned alignment film has been subjected to alignment treatment so that the liquid crystal molecules 12 near the substrate interface are pre-tilted by about 5 to 7 degrees, and the alignment orientations in the substrate plane become the same direction, that is to say, they become parallel alignment. As the liquid crystal molecules 12 stand up gradually away from the substrates 10 and 11 , they become a bend alignment in which the tilt angle of the liquid crystal molecules is 90 degrees substantially at the center in the thickness direction of the liquid crystal layer 13 . Polarizers 15, 16 and optical compensation plates 17, 18 are arranged on the outer sides of the substrates 10, 11. The polarization axes of the above two polarizers 15, 16 are arranged to be perpendicular or parallel to each other, and the orientation directions of the polarizers and the liquid crystal molecules are configured. For a 45-degree angle. In this way, using the difference in the refractive index anisotropy of the liquid crystal layer between the ON state with a high voltage applied and the OFF state with a low voltage applied, as a result, the polarization state of the optical compensation plate is changed to control the polarization of the light. The transmittance is displayed.

In the liquid crystal display device with the above-mentioned bend alignment type OCB unit, since the liquid crystal layer has become a spray alignment before use, it is necessary to transfer the liquid crystal layer from the spray alignment state to the bend alignment state by applying a voltage before the liquid crystal display is driven. state.

FIG. 2 schematically shows an orientation transition mechanism for liquid crystals to transition from spray alignment to bend alignment when a high voltage equal to or higher than the transition threshold voltage is applied for such alignment transition.

2 is a cross-sectional view of a liquid crystal cell in a case where two substrates are arranged in parallel, schematically showing liquid crystal molecules and schematically showing the arrangement of liquid crystal molecules.

Figure 2(a) shows the initial jet alignment state. When there is no electric field between the substrates, the long axis of the liquid crystal molecules 12 in the center of the liquid crystal layer 13 is already in a spray alignment state with a low energy state substantially parallel to the substrate surface. Here, for convenience of explanation, it is decided to denote liquid crystal molecules parallel to the substrate by reference numeral 12a.

Next, FIG. 2(b) shows the alignment state of liquid crystal molecules when a high voltage is started to be applied between the electrodes (not shown) formed on the substrates 10, 11. The liquid crystal molecules 12 in the center of the liquid crystal layer 13 start to slightly tilt due to the electric field, and as a result, the liquid crystal molecules 12a parallel to the substrate surface move toward one substrate surface (the substrate 11 side in the figure).

Next, FIG. 2(c) shows the alignment state of the liquid crystal molecules after a certain time has elapsed after the voltage is applied. The liquid crystal molecules 12 of the liquid crystal layer 13 are further tilted with respect to the substrate surface, and accordingly, the liquid crystal molecules 12a that are substantially parallel to the substrate surface come near the substrate interface and are strongly restrained by the alignment film.

Next, FIG. 2( d ) shows an alignment state of liquid crystal molecules in which the energy state after transition to the bend alignment is remarkably high. The liquid crystal molecules 12 in the center of the liquid crystal layer 13 become perpendicular to the substrate surface, and the liquid crystal molecules connected to the interface of the alignment film (not shown) on the substrate 10 are subjected to a strong confinement force from the alignment film to maintain an oblique alignment state. At this time, There are almost no liquid crystal molecules 12a facing parallel to the substrate surface that exist in FIGS. 2( a ) to ( c ).

After a certain period of time has elapsed from FIG. 2( d ), the above-mentioned alignment state transitions between the substrates to the bend alignment state shown in FIG. 1 and the transfer ends.

In this way, the transition from splay alignment to bend alignment that occurs when a voltage is applied can be regarded as described above.

However, the place where this transfer occurs is usually a part of the alignment region and is a part where energy is easily transferred, rather than the entire liquid crystal layer in the substrate plane. Usually, in the space that has been dispersed in the gap Transfer nuclei tend to be generated at the peripheral portion or the alignment uneven portion, etc., from which the bend alignment region expands. Therefore, in order to perform alignment transition in the OCB cell, it is necessary to generate transition nuclei in at least a part of the liquid crystal layer in the substrate plane, and to supply energy from the outside to transition from the spray alignment state to the bend alignment state and maintain the transition.

Considering the results of such an orientation transfer mechanism, the present inventors have completed a liquid crystal display device, a method of manufacturing the same, and a driving method of a liquid crystal display device that reliably generate transfer nuclei and complete the transfer in an extremely short time. The content will be described according to the implementation plan.

(implementation 1)

FIG. 3 is a schematic diagram showing the configuration of a pixel unit in the driving method of the liquid crystal display device according to Embodiment 1 of the present invention. First, the configuration of the liquid crystal display device related to the driving method of the first embodiment will be described with reference to FIG. 3 . The liquid crystal display device according to the first embodiment has the same configuration as a general liquid crystal display device including an OCB cell except for the driving circuit portion. That is, it has a pair of glass substrates 20 and 21 and a liquid crystal layer 26 sandwiched between the glass substrates 20 and 21 . The glass substrates 20 and 21 are arranged facing each other with a constant interval therebetween. A common electrode 22 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 20 , and a pixel electrode 23 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 21 . Alignment films 24, 25 made of polyimide films are formed on the common electrode 22 and the pixel electrode 23, and the alignment films 24, 25 have been subjected to an alignment process so that the alignment directions are parallel to each other. Then, a liquid crystal layer 26 made of P-type nematic liquid crystal is inserted between the alignment films 24 and 25 . In addition, the pretilt angle of the liquid crystal molecules on the alignment films 24 and 25 was set to about 5 degrees, and the threshold voltage for transition from splay alignment to bend alignment was set to 2.5V. The optical path difference of the optical compensation plate 29 is selected so as to display white or black in the ON state. In addition, in FIG. 1 , 27 and 28 are polarizers.

In addition, in the drawing, 30 is a drive circuit for orientation transition, and 31 is a drive circuit for liquid crystal display. In addition, 32a, 32b are switch circuits, and 33 is a switch control circuit which controls switching of the switching state of the switch circuits 32a, 32b. The switch circuit 32a has two individual contacts P1, P2 and one common contact Q1, and the switch circuit 32b has two individual contacts P3, P4 and one common contact Q2. The common contact Q1 is connected to any one of the individual contacts P3 and P4 according to the switch switching signal S1 from the switch control circuit 33 . In the state where the common contact Q1 is connected to the individual contact P1 and the common contact Q2 is connected to the individual contact P3, the driving voltage from the orientation transfer driving circuit 30 is applied to the electrodes 22 and 23 as a result. In addition, in the state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, as a result, the drive voltage from the drive circuit 31 for liquid crystal display is applied to the electrodes 22, 23. superior.

Next, the driving method of the first embodiment will be described.

First, before the liquid crystal display is driven based on the original image signal, an initialization process is performed in order to perform transition to the bend alignment. First, by turning on the power, the switch control circuit 33 outputs switch switching signals S1, S2 to the switch circuits 32a, 32b, connects the common contact Q1 to the individual contact P1 and connects the common contact Q2 to the individual contact P3 superior. With this, the drive voltage shown in FIG. 4 is applied between the electrodes 22 and 23 from the drive circuit 30 for orientation transfer. This driving voltage, as shown in FIG. 4, is an AC voltage in which a square wave voltage A and a bias voltage B are superimposed, and the value of the driving voltage is set to a value higher than that necessary for transition from splay alignment to bend alignment. The threshold voltage of the minimum voltage is also a large voltage value. By applying such a driving voltage, the transfer time can be significantly shortened compared with the conventional example of applying a simple AC voltage. In addition, the reason for shortening the transition time will be described later. In this way, the initialization processing related to the transition to the bend orientation is completed.

Then, after the transfer time for the entire electrode to be completely transferred to the bend orientation, the switch control circuit 33 outputs a switch signal S1 to the switch circuit 33a to switch the common contact Q1 to the side of the individual contact P2, and at the same time to the switch circuit 33a 32b outputs a switching signal S2 for switching the common contact Q2 to the side of the individual contact P4. By virtue of this, the common contact Q1 is connected to the individual contact P2, and the common contact Q2 is connected to the individual contact P4. As a result, the drive signal voltage from the liquid crystal display drive circuit 31 is applied to the electrodes 22, Between 23, the desired image is displayed. Here, the drive circuit 31 for liquid crystal display generates a 30Hz, 2.7V square wave voltage to maintain the bend alignment state and turns it OFF, and turns a 30Hz, 7V square wave voltage to the ON state to display on the OCB panel.

Next, the present inventors manufactured a liquid crystal display device having the above-mentioned configuration, and conducted an experiment of initializing processing using the above-mentioned driving method, and the results will be described below. In addition, the experimental conditions are as follows.

Assuming that the electrode area is 2 cm ² , the cell gap is about 6 microns, the frequency of the AC square wave voltage A is 30 Hz, and the amplitude is ±4 V.

Under the above conditions, the respective transition times were measured when the bias voltage was set to four voltages of 0V, 2V, 4V, and 5V, and the results are shown in FIG. 5 . Here, the so-called transfer time refers to the time required to complete orientation transfer in the entire area of the electrode.

It can be seen from FIG. 5 that when the bias voltage B is 0V, the transfer time needs to be 140 seconds. On the contrary, if the bias voltage B is set to 4V, the transfer time becomes 8 seconds, so it can be shortened. This is because by virtue of the overlapping of bias voltages, the orientation of the liquid crystal molecules in the liquid crystal layer is swayed by the bias voltage and is biased to one side between the substrates as shown in Figure 2(d), thus generating more transfer nuclei, and the increase of the effective voltage makes This is due to the further acceleration of the transfer time.

By continuously applying the AC voltage superimposed on the bias voltage as described above, the transfer time can be shortened compared with the case of applying a simple AC voltage.

In the above-mentioned experimental example, although the AC square wave voltage signal is 30Hz, the value of ± 4V, but the present invention is not limited thereto, as long as it is the frequency that makes the liquid crystal operate, for example, also can be the value such as 10kHz, in addition, if Increase the amplitude of AC voltage A, of course, the transfer time will become faster. At this time, the higher the bias voltage is superimposed, the faster it will be. However, considering the lowering of the drive voltage, the bias voltage is ideally set to an optimum voltage level corresponding to the transition time. In addition, although a square wave is used as the waveform, an AC waveform having a different duty ratio may be used.

(implementation 2)

FIG. 6 is a schematic diagram showing the configuration of a pixel unit of a liquid crystal display device according to Embodiment 2. FIG. In the second embodiment, it is characterized in that the step of applying an AC voltage superimposed on the bias voltage between the above-mentioned substrates and the step of making the above-mentioned substrates into an electrically disconnected state (OPEN state) are alternately repeated, so that the liquid crystal The layer is transferred from splay orientation to bend orientation.

In the liquid crystal display device according to the second embodiment, the same components as those in the first embodiment are given the same reference numerals and their descriptions are omitted. In Embodiment 2, instead of using the drive circuit 30, switch circuit 32a, and switch control circuit 32 for orientation transfer in Embodiment 1, the drive circuit 40, switch circuit 42a, and switch control circuit 43 for orientation transfer are used instead. The switch circuit 42a is a three-terminal switching circuit including an individual contact P5 in addition to the individual contacts P1 and P2. Switching of the switch circuit 42 a is controlled by the switch control circuit 43 . In addition, the drive circuit 40 for orientation transfer applies the drive voltage shown in FIG. 7 between the substrates 22 and 23 . This driving voltage, as shown in FIG. 7, is a voltage in which an AC voltage C and a bias voltage D are superimposed, and the value of the driving voltage is set to be smaller than the minimum required for transition from spray alignment to bend alignment. The threshold voltage of the voltage is also a larger voltage value.

Also, the common contact Q1 of the switch circuit 42a is connected to any one of the individual contacts P1, P2, and P5 by the switch switching signal S3 from the switch control circuit 43. In the state where the common contact Q1 is connected to the individual contact P5, the electrodes 22 and 23 are in an OPEN state disconnected from the drive circuit 40 for orientation transition. In a state where the common contact Q1 is connected to the individual contact P1 and the common contact Q2 is connected to the individual contact P3, the drive voltage from the drive circuit 40 for orientation transfer is applied to the electrodes 22, 23 as a result. Also, in a state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, the drive voltage from the liquid crystal display drive circuit 31 is applied to the electrodes 22, 23 as a result.

Next, the driving method of the second embodiment will be described.

First, before the liquid crystal display is driven based on the original image signal, an initialization process is performed in order to perform transition to the bend alignment. First, by turning on the power supply, the switch control circuit 43 outputs the switch switching signal S3 to the switch circuit 42a, and at the same time outputs the switch switching signal S2 to the switch circuit 32b, so that the common contact Q1 and the individual contact P1 become connected, and, The common contact Q2 and the individual contact P3 are brought into a connected state. With this, the drive voltage shown in FIG. 7 is applied between the electrodes 22 and 23 from the drive circuit 40 for orientation transfer. Then, after a certain time T2 has elapsed, the switch control circuit 43 outputs a switch switching signal S3 to the switch circuit 42a to bring the common contact Q1 and the individual contact P5 into a connected state. With this, the electrodes 22 and 23 are disconnected from the drive circuit 40 for orientation transition to be in an OPEN state. Such an OPEN state is maintained for a time period W2, and during this OPEN state period W2, between the electrodes 22 and 23 will be in a charge hold state.

After the OPEN state period W2 elapses, the switch control circuit 43 outputs the switch switching signal S3 to the switch circuit 42a, and the common contact Q1 and the individual contact P1 are brought into a connected state again. Then, such driving for orientation transition and the OPEN state are alternately repeated, and after a certain period of time has elapsed since the power was turned on, the entire electrode is completely transitioned to the bend orientation.

Then, after the certain period has elapsed, the switch control circuit 43 outputs the switch switching signal S3 to the switch circuit 42a, and at the same time outputs the switch switching signal S2 to the switch circuit 32b, so that the common contact Q1 and the individual contact P2 are brought into a connected state, Furthermore, the common contact Q2 and the individual contact P4 are in a connected state. With this, the driving signal voltage from the driving circuit 31 for liquid crystal display is applied between the electrodes 20, 21, and a desired image can be displayed. Here, the drive circuit 31 for liquid crystal display, similarly to the first embodiment, generates a 30Hz, 2.7V square wave voltage to maintain the bend alignment state and turns it OFF, and turns a 30Hz, 7V square wave voltage into the ON state. , to make the OCB panel display.

Next, the present inventors manufactured a liquid crystal display device having the above-mentioned configuration, and conducted an experiment of initialization processing by the above-mentioned driving method, and the results thereof will be described below. Additional experimental conditions are as follows.

The electrode area is 2cm2, the cell gap is about 6 microns, the bias voltage B is 2V, the frequency of the AC square wave voltage D is 30Hz, the amplitude is ±4V, and the voltage application time T2 is fixed at 2 seconds.

Under the above conditions, the transition time was measured when the voltage application state and the OPEN state were alternately repeated by changing the OPEN state time W2 to 0 seconds, 0.2 seconds, 2 seconds, and 3 seconds. FIG. 8 shows the results. Here, the so-called transfer time refers to the time required to complete orientation transfer in the entire area of the electrode.

It can be seen from FIG. 8 that when the time W2 in the OPEN state is 0 seconds, that is to say, when the AC voltage superimposed on the bias voltage is continuously applied, the transfer time needs 80 seconds. On the other hand, if the OPEN state time W2 is set at 0.2 seconds, and alternately and repeatedly switched with the AC voltage superimposed on the above-mentioned bias voltage, the transition time is shortened to 40 seconds. But, if the OPEN state time W2 is set as 2 seconds, then conversely, the transfer time will be stretched to 420 seconds, if W2 is set as 3 seconds, then it is impossible to complete the transfer.

By the way, good results were obtained when T2 was set at 2 seconds and W2 was set at 0.1 to 0.5 seconds.

The reason why the state transition time from splay alignment to bend alignment is extremely short by repeatedly switching the biased AC voltage and the OPEN state as described above is considered to be as follows. That is, due to the addition of the AC voltage that has been superimposed on the bias voltage, the orientation of the liquid crystal molecules in the liquid crystal layer is shaken, and as shown in FIG. The switching of the OPEN state of the transfer core occurs, thus making the transfer time faster.

In the above description, before or after the AC voltage superimposed on the bias voltage is applied, another voltage signal is added, even if the OPEN state is entered secondly, the above effect can also be obtained.

In addition, the voltage value of the bias voltage or the AC voltage, the voltage application time, or the maintenance time of the OPEN state can be selected according to the required transition time. The frequency of the AC voltage may be any frequency at which the liquid crystal operates, and may be a value such as 10 kHz, for example. Although a square wave is used as the waveform, an AC waveform having a different duty ratio may be used.

(Embodiment 3)

FIG. 9 is a schematic diagram showing the configuration of a pixel unit of a liquid crystal display device according to Embodiment 3. FIG. In this embodiment 3, it is characterized in that it includes: alternately repeating the step of applying an AC voltage superimposed on the bias voltage between the above-mentioned substrates and the step of applying a zero voltage or a low voltage between the above-mentioned substrates to make the liquid crystal The layer is transferred from splay orientation to bend orientation.

In the liquid crystal display device according to the third embodiment, the same components as those in the liquid crystal display device according to the second embodiment are assigned the same reference numerals, and description thereof will be omitted. In the third embodiment, the switch circuit 32b and the switch control circuit 43 of the second embodiment are not used, but the switch circuit 42b and the switch control circuit 53 are used instead. In the third embodiment, instead of the drive circuit 40 for orientation transition, the drive circuit 50 for applying a low voltage between the electrodes 22 and 23 is provided.

The switch circuit 42b is a three-terminal switching circuit including an individual contact P6 in addition to the individual contacts P3 and P4. Switching of the switch circuit 42 b is controlled by the switch control circuit 53 . In addition, the common contact Q2 of the switch circuit 42 b is connected to any one of the individual contacts P3 , P4 , and P5 by the switch switching signal S4 from the switch control circuit 53 .

In a state where the common contact Q1 is connected to the individual contact P1 and the common contact Q2 is connected to the individual contact P3, the drive voltage from the orientation transfer drive circuit 40 is applied to the electrodes 22 and 23 as a result. In addition, in the state where the common contact Q1 is connected to the individual contact P5, and the common contact Q2 is connected to the individual contact P6, as a result, the drive voltage from the drive circuit 50 for orientation transfer is applied to the electrodes 22 and 23. . Furthermore, in the state where the common contact Q1 is connected to the individual contact P2 and the common contact Q2 is connected to the individual contact P4, as a result, the drive voltage from the liquid crystal display drive circuit 31 is applied to the electrodes 22 and 23. .

Next, the driving method of the third embodiment will be described.

First, before the liquid crystal display is driven based on the original image signal, an initialization process is performed in order to perform transition to the bend alignment. First, by turning on the power supply, the switch control circuit 53 outputs the switch switching signal S3 to the switch circuit 42a, and at the same time, outputs the switch switching signal S2 to the switch circuit 42b, so that the common contact Q1 and the individual contact P1 are in a connected state, and, The common contact Q2 and the individual contact P3 are brought into a connected state. With this, the drive voltage shown in FIG. 10 is applied between the electrodes 22 and 23 from the drive circuit 40 for orientation transfer. Then, after a certain time T3 has elapsed, the switch control circuit 53 outputs the switch switching signal S3 to the switch circuit 42a, and at the same time outputs the switch switching signal S2 to the switch circuit 42b, so that the common contact Q1 and the individual contact P5 are in a connected state. , Moreover, the common contact Q2 and the individual contact P6 are brought into a connected state. With this, the low voltage shown in FIG. 10 is applied between the electrodes 22 and 23 from the drive circuit 50 for orientation transfer. Such low voltage application can be maintained during the period W3.

Next, after the low voltage application period W3 has elapsed, the switch control circuit 53 outputs the switch control signal S3 to the switch circuit 42a, and at the same time outputs the switch control signal S2 to the switch circuit 42b, again making the common contact Q1 and the individual contact P1 become The connection state, and the common contact Q2 and the individual contact P3 are in the connection state. Then, such an AC voltage application step and a low voltage application step are repeated alternately, and after a certain period of time has elapsed since the power was turned on, the entire electrode is completely shifted to the bend orientation.

Then, after the certain period has elapsed, the switch control circuit 53 outputs the switch switching signal S3 to the switch circuit 42a, and at the same time outputs the switch switching signal S2 to the switch circuit 42b, so that the common contact Q1 and the individual contact P2 are brought into a connected state, Furthermore, the common contact Q2 and the individual contact P4 are in a connected state. With this, the driving signal voltage from the driving circuit 31 for liquid crystal display is applied between the electrodes 20, 21, and a desired image can be displayed. Here, the drive circuit 31 for liquid crystal display, similarly to the first embodiment, generates a 30Hz, 2.7V square wave voltage to maintain the bend alignment state and turns it OFF, and turns a 30Hz, 7V square wave voltage into the ON state. , to make the OCB panel display.

Next, the present inventors manufactured a liquid crystal display device having the above-mentioned configuration, and conducted an experiment of initialization processing by the above-mentioned driving method, and the results will be described below. Additional experimental conditions are as follows.

The electrode area is 2cm ² , the cell gap is about 6 microns, the bias voltage D is 2V, the frequency and amplitude of the AC square wave voltage C are 30Hz, ±4V, and the voltage application time T3 is fixed at 1 second. Also, the applied voltage in W3 during the low voltage application period is a DC voltage of -2V.

Under the above conditions, the transition time was measured when the low voltage application period W3 was changed and the AC voltage application state and the low voltage application state were alternately repeated, and the results are shown in FIG. 11 .

It can be seen from FIG. 11 that when the low voltage application time is 0 seconds, that is to say, when the AC voltage superimposed with the bias voltage is continuously applied, the transfer time needs 80 seconds. On the other hand, if the low voltage application time W3 is set at 0.1 second and alternately switched repeatedly with the AC voltage superimposed on the bias voltage, the transfer time is shortened to 60 seconds. However, if the low voltage application time W3 is set to 1 second, then in turn, the transfer time will be extended to 360 seconds, and if W3 is set to 3 seconds, it is impossible to complete the transfer.

In addition, if the ±4V AC voltage and the DC voltage 0V are repeatedly switched, the transfer can be completed within 50 seconds at the shortest. In addition, if the ±4V AC voltage and the DC voltage ±2V that have been superimposed on the 2V bias voltage are repeatedly switched, the shortest transfer time within 50 seconds can be obtained.

By the way, when T3 is set to 1 second and W2 is set to 0.1 second to 0.5 second, good results can be obtained.

By repeatedly switching between the application of the AC voltage and the application of the low voltage with the superimposed bias voltage as described above, the transition time from the spray alignment to the bend alignment can be made shorter than that of the continuous application of the superimposed bias voltage. The case of AC voltage is also short. It is believed that this is because the orientation of the liquid crystal molecules in the liquid crystal layer is shaken by applying an AC voltage that has been superimposed on the bias voltage, and the orientation of the liquid crystal molecules between the substrates becomes disordered as shown in Figure 2(d). This is because transition nuclei are generated by switching to a short low voltage application state, thereby making the transition time faster.

In addition, the voltage value of the bias voltage or the AC voltage, the voltage application time, or the maintenance time of the OPEN state can be selected according to the required transition time. The frequency of the AC voltage may be any frequency at which the liquid crystal operates, and may be a value such as 10 kHz, for example. Although a square wave is used as the waveform, an AC waveform having a different duty ratio may be used.

In addition, in the above-mentioned example, in the low voltage application period W3, although the low voltage of -2V was made to apply, 0V may be made to apply.

Next, the ratio of the AC voltage application period T3 to the low voltage application period W3 and the number of repetitions of the AC voltage application and the low voltage application per second will be described. Here, for convenience of description, the voltage in W3 during the low voltage application period is assumed to be 0V, and the alternating repetition of AC voltage application and 0V application, as shown by dotted line L in FIG. 10, is regarded as a transfer voltage. In this case, in order to shorten the transfer time, the frequency of the transfer voltage L ranges from 0.1 Hz to 100 Hz, and the duty ratio of the transfer voltage must be set in the range from 1:1 to 1000:1. In addition, it is desirable that the frequency range of the transfer voltage is from 0.1 Hz to 10 Hz, and that the duty ratio of the transfer voltage is in the range of 2:1 to 1000:1. The reason for this will be described below.

Transition, in the range of the duty ratio of repeated voltage application from 1:1 to 1:10, even if the transition nucleus occurs by applying the pulse width, the voltage application rests at the subsequent pulse interval in the specified The cool down time also returns to the spray orientation, which is considered to be an incomplete transfer. In order to expand the transfer region, the duty ratio may range from 1:1 to 1000:1, ideally from 2:1 to 100:1, where the pulse width becomes wider than the pulse interval. If it is from 1000:1 to direct current continuous, since it is the direction in which the repeated application of pulses is almost no longer performed, it is considered that the chance of occurrence of transition nuclei is reduced, and thus the transition becomes longer.

In addition, although the above-mentioned repetition frequency of voltage application for transfer can be from continuous to about 100 Hz, in order to perform transfer amplification, it is ideal to be from 10 Hz at which a pulse width of about 100 ms or more can be obtained to a duty ratio of 1000:1 and can be obtained. About 0.1Hz for pulse intervals above 10ms.

In addition, the present inventors measured the transition time in the case of applying a voltage to the liquid crystal cell by changing the repetition frequency and the duty ratio under the repeated condition of alternating DC-15V and 0V, and the results are shown in Table 1. .

Table 1

(unit: second)

From Table 1, it can be confirmed that the transition time is extremely small in the frequency range from 0.1 Hz to 10 Hz and the duty ratio in the range from 2:1 to 1000:1, even at frequencies from The transition time will also become sufficiently small in the range of 0.1 Hz to 100 Hz with a duty ratio in the range of 1:1 to 1000:1.

(Embodiment 4)

FIG. 12 is a schematic diagram showing the configuration of a pixel unit of a liquid crystal display device according to Embodiment 4. FIG. In Embodiment 4, an example in which the present invention is applied to a driving method of an active matrix type liquid crystal display device is shown.

First, referring to FIG. 12, the configuration of a liquid crystal display device related to the driving method of the fourth embodiment will be described. The liquid crystal display device according to the fourth embodiment has the same configuration as that of a general active matrix type liquid crystal display device including OCB cells except for the driving circuit portion. That is, it has a pair of glass substrates 60 and 61 and a liquid crystal layer 66 sandwiched between the glass substrates 60 and 61 . The glass substrates 60 and 61 are arranged to face each other at a predetermined interval. A common electrode 62 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 60 , and a pixel electrode 63 made of an ITO transparent electrode is formed on the inner surface of the glass substrate 61 . Alignment films 64 and 65 made of polyimide films are formed on the common electrode 62 and the pixel electrode 63, and the alignment films 64 and 65 have been subjected to an alignment process so that the alignment directions are parallel to each other. Then, a liquid crystal layer 66 made of P-type nematic liquid crystal is inserted between the alignment films 64 and 65 . In addition, the pretilt angle of the liquid crystal molecules on the alignment films 64 and 65 was set to about 5 degrees, and the threshold voltage for transition from spray alignment to bend alignment was set to 2.6V. The optical path difference of the optical compensation plate 67 is selected so as to display white or black in the ON state. In addition, in the drawing, 68 and 69 are polarizers.

In addition, in the figure, 71 and 72 are drive circuits for orientation transfer. The drive circuit 71 for orientation transfer applies a drive voltage to the common electrode 62 based on the center of the common electrode shown in FIG. The effect of adding 0V to the prime electrode 63 . In addition, as another configuration, the driving circuit 72 for orientation transition functions to apply 0 V to the common electrode 62 and the pixel electrode 63 . In addition, 73 is a driving circuit for liquid crystal display, and the driving circuit 73 for liquid crystal display functions to apply a driving voltage having a voltage waveform shown in FIG. 13 to the common electrode 62 and the pixel electrode 63 . That is, the driving circuit 73 for liquid crystal display applies the voltage indicated by reference numeral M1 in FIG. 13 to the pixel electrode 63 and applies the voltage indicated by reference numeral M2 in FIG. 13 to the common electrode 62 . In addition, if the above configuration is used, during the orientation transition period, 0V is applied to the pixel electrode 63, but this may not be done. Instead, even during the orientation transition period, the liquid crystal display The pixel electrode voltage is applied by the driving circuit 73 .

In addition, 74a, 74b are switch circuits, and 75 is a switch control circuit which controls switching of the switching pattern of the switch circuits 74a, 74b. The switch circuit 74a has three individual contacts P7, P8, P9 and one common contact Q1, and the switch circuit 74b has three individual contacts P10, P11, P12 and one common contact Q2. In the state where the common contact Q1 is connected to the individual contact P7 and the common contact Q2 is connected to the individual contact P10, the drive voltage from the drive circuit 71 for orientation transfer is applied to the electrodes 62 and 63 as a result. . In addition, in the state where the common contact Q1 has been connected to the individual contact P8 and the common contact Q2 has been connected to the individual contact P11, as a result, the drive voltage from the drive circuit 73 for liquid crystal display is applied to the electrodes 62, 63 on.

Next, the driving method of the fourth embodiment will be described.

First, before the liquid crystal display is driven based on the original image signal, an initialization process is performed in order to perform transition to the bend alignment. First, by turning on the power supply, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a, and at the same time outputs a switch switching signal to the switch circuit 74b, so that the common contact Q1 and the individual contact P7 are in a connected state, and the common contact Q1 is connected. Point Q2 and individual contact P10 are in a connected state. With this, the drive voltage shown in FIG. 14 is applied to the electrode 62 from the drive circuit 71 for orientation transfer. That is, with the center of the common electrode as a reference, an AC voltage synchronous with the center of the common electrode superimposed on -GV is applied. In addition, 0V is applied to the pixel electrode. Then, the application of the AC voltage is maintained during the period T4.

Next, after the AC voltage application period T4 has elapsed, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a, and at the same time outputs a switch switching signal to the switch circuit 74b, so that the common contact Q1 and the individual contact P9 are in a connected state, Furthermore, the common contact Q2 and the individual contact P12 are brought into a connected state. With this, 0 V is applied to the common electrode 62 and the pixel electrode 63 from the drive circuit 72 for orientation transition, as shown in FIG. 14 . The application of this 0V voltage is maintained during the period W4.

Next, after the 0V voltage application period W4 has elapsed, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a, and at the same time outputs a switch switching signal to the switch circuit 74b, and the common contact Q1 and the individual contact P7 are brought into a connected state again. , and make the common contact Q2 and the individual contact P10 into a connected state. Such an AC voltage application step and a 0V voltage application step are alternately repeated, and after a certain period of time has elapsed since the power was turned on, the entire electrode is completely shifted to the bend orientation.

Then, after the certain period has elapsed, the switch control circuit 75 outputs a switch switching signal to the switch circuit 74a, and simultaneously outputs a switch switching signal to the switch circuit 74b, so that the common contact Q1 and the individual contact P8 are connected, and , making the common contact Q2 and the individual contact P11 into a connected state. As a result, the driving signal voltage from the liquid crystal display driving circuit 73 is applied between the electrodes 62, 63, and a desired image is displayed. Here, the drive circuit 73 for liquid crystal display sets the drive voltage 2.7V for maintaining the bend alignment state between the two electrodes as the lowest and turns it OFF, and sets the upper limit voltage as 7V and turns it ON. OCB panel for display.

By using the driving method described above, a bend alignment type OCB active matrix liquid crystal display device with a wide field of view and high-speed response can perform high-quality drive display without any alignment defects.

Next, the present inventors manufactured a liquid crystal display device having the above-mentioned configuration, and conducted an experiment of initializing processing using the above-mentioned driving method, and the results will be described below. Additional experimental conditions are as follows.

The cell gap is about 6 microns, the bias voltage G is -6V, the frequency and amplitude of the AC square wave voltage are 7.92Hz, ±10V, and the voltage application time T3 is fixed at 0.5 seconds. In addition, W4 is set to 0.5 seconds during the 0V voltage application period.

If the above experimental results are adopted, the alignment transfer in all pixels of the panel of the above-mentioned liquid crystal display device can be completed within approximately 2 seconds.

In addition, when the bias voltage is not superimposed, it takes about 20 seconds to transition the orientation state of the entire display surface. Therefore, it is considered that the transition time can be shortened even if the bias voltage is superimposed and driven in the fourth embodiment.

(Embodiment 5)

As a driving method related to orientation transition of an OCB mode active matrix liquid crystal display device, the driving voltage waveform shown in FIG. 15 may be used instead of the driving voltage waveform shown in FIG. 14 for driving. That is, during the AC voltage application period W4, a DC voltage of −15 V is applied to the common electrode 62 with the center of the common electrode as a reference for 0.2 seconds. Then, the DC voltage -15V application and the 0V voltage application were repeated alternately. Also in such a driving method, transfer can be completed reliably and in an extremely short time.

In addition, the present inventors conducted experiments using the above-mentioned driving method, and found that a transition time within 2 seconds can be obtained.

(Embodiment 6)

The sixth embodiment is characterized in that instead of the active-matrix liquid crystal display device used in the fourth and fifth embodiments, the driving method of the fourth and fifth embodiments is applied to disposing a planarizing film on the switching device. In a liquid crystal display device composed of a planarization film on which a pixel electrode is formed. The driving method will be specifically described below. The voltage for orientation transition superimposed with the bias voltage in Embodiment 4 above was applied for 0.5 seconds, followed by the OPEN state for 0.5 seconds, and the above procedure was alternately repeated. If this driving method is adopted, the transfer time is within 1 second and the transfer can be performed more smoothly. This is because the distance between the pixel electrodes can be reduced by the flattening film structure, so that the transition from the splay alignment to the bend alignment can be smoothly performed.

(other matters)

① In the above-mentioned embodiment, although an AC voltage with superimposed bias voltage is added, it is also possible to add a DC voltage. In this case, the driving circuit can be simplified because it can also be a unipolar voltage. ② In the above embodiment, although the bias voltage is superimposed on the AC voltage signal and the bias voltage is described as DC, it may be a low-frequency AC signal in order to improve reliability. ③ The optimum ranges of the frequency and duty ratio of the repetitive voltage can also be applied to embodiments other than the third embodiment. ④ In the above embodiments, the driving method of the liquid crystal display device according to the invention has been described using a transmissive liquid crystal display device, but a reflective liquid crystal display device may also be used. In addition, a full-color liquid crystal display device using a full-color color filter or a liquid crystal display device without a color filter may also be used.

(Embodiment 7)

16 is a schematic sectional view of a liquid crystal display device according to Embodiment 7 of the present invention, and FIG. 17 is a schematic plan view of the same device.

The liquid crystal display device shown in Figure 16 has polarizing plates 101, 102, a phase compensating plate 103 for optical compensation arranged inside the polarizing plate 101, and an active matrix liquid crystal cell arranged between the above-mentioned polarizing plates 101, 102. 104.

The above-mentioned liquid crystal unit 104 has an array substrate 106 made of glass or the like and an opposing substrate 105 facing the array substrate 106, and a pixel electrode 108 is formed on the inner surface of the array substrate 106, and a common electrode is formed on the inner surface of the above-mentioned opposing substrate 105. 107. Further, an alignment film 110 is formed on the pixel electrode 108 , and an alignment film 109 is formed on the common electrode 107 .

In addition, a switching device 111 composed of, for example, an a-Si-based TFT device or the like is disposed on the array substrate 106 , and the switching device 111 is connected to the pixel electrode 108 .

In addition, between the above-mentioned alignment films 109 and 110, spacers with a diameter of 5 micrometers not shown and a liquid crystal layer 112 made of a nematic liquid crystal material having positive dielectric constant anisotropy are arranged. In addition, the pretilt angles of the liquid crystal molecules on the surfaces of the alignment films 109 and 110 have opposite positive and negative values, and are parallel-aligned in the same direction so that they are substantially parallel to each other. Therefore, in the above-mentioned liquid crystal layer 112, in a state where no voltage is applied, a so-called squirt alignment is formed, which is composed of an alignment region in which liquid crystal molecules spread obliquely.

In addition, the alignment film 110 is composed of an alignment film 110a having a large pretilt angle B2 (third pretilt angle) and an alignment film 110b having a small pretilt angle A2 (first pretilt angle). In addition, the alignment film 109 is composed of an alignment film 109a having a small pretilt angle D2 (the fourth pretilt angle) and an alignment film 109b having a large pretilt angle C2 (the second pretilt angle). The pretilt angle C2 is arranged opposite to the pretilt angle A2, and the pretilt angle D2 is arranged opposite to the pretilt angle B2.

In addition, the alignment films 109 and 110 were parallel-aligned in the same direction on the upper and lower substrates in a direction substantially at right angles to the signal electrode lines 113 using a rubbing cross.

Next, a method of manufacturing the liquid crystal display device will be described.

First, signal scanning lines 113 , switching devices 111 and pixel electrodes 108 are formed on the inner surface of the array substrate 106 .

Then, on the above-mentioned pixel electrode 108, the polyimide of the polyamic acid type produced by Nissan Chemical Industry Co., Ltd. as the third pretilt angle with a large value of about 5 degrees is applied. The alignment film material is dried and then fired to form the alignment film 110 a on the pixel electrode 108 .

Then, ultraviolet rays were irradiated on the left side of the alignment film 110a to change the pretilt angle A2 as the first pretilt angle to a small value of about 2 degrees to form the alignment film 110b.

A common electrode 107 is formed on the inner surface of the opposing substrate 105 .

Then, on the common electrode 107, a polyacid type polyacid type manufactured by Nissan Chemical Industries Co., Ltd. that imparts a pretilt angle C2, which is a second pretilt angle having a large value of about 5 degrees, to interface liquid crystal molecules is applied. The polyimide alignment film material is dried and then fired to form the alignment film 109 b on the common electrode 107 .

Then, ultraviolet rays are irradiated to the right side region (the region facing the pretilt angle B2 having a large value of the pretilt angle) on the paper surface of the above-mentioned alignment film 109b to make the pretilt angle D2 as the 4th pretilt angle By changing a small value of about 2 degrees, an alignment film 109a is formed.

As described above, as shown in FIG. 26 , the pretilt angle C2 (second pretilt angle) with a large value can be disposed opposite to the pretilt angle A2 (first pretilt angle) with a small value, and can be compared with The pretilt angle D2 (42 pretilt angles) having a small value is arranged to face the pretilt angle B2 having a large value (the third pretilt angle).

In addition, the pretilt angle can also be controlled as follows.

That is, as shown in FIG. 18(a), an active matrix switching device (not shown) composed of a-Si TFT devices or the like is formed on the array substrate 106, and a pixel is formed by connecting to the device. electrode 108 .

Next, as shown in FIG. 18(b), ultraviolet rays are irradiated to the left region of the pixel electrode 108 in an ozone atmosphere, and compared with the right region of the pixel electrode 108, the planarization is performed to form a planarized region 108a.

Then, as shown in FIG. 18( c ), an alignment film 110 is formed by applying a preimide type polyimide alignment material produced by JSR Co., Ltd. to dry or sinter on the pixel electrode 108 .

When formed in this way, the pretilt angle of the liquid crystal molecules 140 located on the flattened region of the pixel electrode 108 can be made smaller than the pretilt angle of the liquid crystal molecules 140 located on the unplanarized region 108a. In addition, by performing the same treatment on the common electrode, a liquid crystal display device having a first liquid crystal cell region and a second liquid crystal cell region in the same pixel can be fabricated as in FIG. 16 .

Next, as shown in FIG. 16, the surfaces of the alignment film 109 and the alignment film 110, which are formed as above and mutually impart large and small pretilt angles, are ground in a direction perpendicular to the signal electrode line 113 with a polishing cross tube. Parallel alignment treatment is performed on the upper and lower substrates in the same direction (from left to right in FIG. 16 ), and a liquid crystal layer 112 made of a positive nematic liquid crystal material is arranged.

In the liquid crystal display device produced in this way, the small pretilt angle A2 is arranged at the alignment source of the above-mentioned pixel electrode 108 (the upstream side of the polishing process direction), and the large pretilt angle C2 is arranged there. On the opposite side, when 2.5V is added as the first voltage between the common electrode 107 and the pixel electrode 108, in the (I) region (the first liquid crystal cell region) of the pixel in Fig. 16, it is easy to The b-spray alignment 120 in which the liquid crystal molecules are sprayed and aligned on the array substrate 106 side is formed, and in the (II) region (the second liquid crystal cell region) of the pixel, it is easy to form a liquid crystal molecule that is sprayed on the opposite substrate 105 side. Oriented t-spray orientation 121.

That is, as shown in FIGS. 16 and 17, when 2.5V as the first voltage is applied between the common electrode 107 and the pixel electrode 108 through the switching device 111 of the above-mentioned liquid crystal cell 104, a b-spray is formed in the pixel. The alignment region (the first liquid crystal cell region) and the t-spray alignment region (the second liquid crystal cell region) clearly form a spiral along the signal electrode line 113 and straddle the gate electrode lines 114, 114' on their boundaries. The disclination line 123 (a disclination line formation process).

In addition, by repeatedly applying a pulse of -15 V as the second voltage between the common electrode 107 and the pixel electrode 108, as shown in FIG. The transition to the bend orientation 124 is extended, and the entire pixel of the TFT panel is rapidly transitioned in about 3 seconds (orientation transition process).

This is thought to be due to the disclination line region which itself is the boundary of the b-spray orientation state and the t-spray orientation region. The energy of the distortion becomes higher than that of the surrounding area. In this state, a high voltage is applied between the upper and lower electrodes to supply energy, and the squirt orientation shifts to the bend orientation.

(Embodiment 8)

Fig. 19 shows a schematic diagram of a liquid crystal display device according to Embodiment 8 of the present invention.

During normal display, the gate electrode lines are sequentially turned ON for scanning, but before normal display, the gate electrode lines are sequentially turned ON, and are repeatedly applied as the first voltage between the common electrode 107 and the pixel electrode 108. By applying a pulse voltage of -15V, a lateral electric field due to a potential difference is generated between the pixel electrode 108 and the gate electrode lines 114, 114'. Next, with the help of the above-mentioned transverse electric field, as shown in FIG. 19, transfer nuclei are generated from the vicinity of the disclination line 123 and the gate electrode lines 114, 114', and the transition to the bend orientation is expanded, and the entire TFT panel is used within about 1 second. The expansion transition to the bend orientation is carried out (orientation transition step).

This is considered to be because the distortion energy of the disclination line region, which is the boundary between the b-spray alignment state and the t-spray alignment region, becomes higher than that of the surroundings. The misalignment plus the transverse electric field provides more energy for rapid transfer. In addition, after the transfer is completed, the gate electrode lines 114, 114' return to the normal scanning state.

In addition, the second voltage applied between the pixel electrode and the common electrode may be continuously applied. In addition, in the case of repeatedly applying a pulse-like voltage, the frequency ranges from 0.1 Hz to 100 Hz, and the duty ratio of the second voltage can be obtained at least in the range from 1:1 to 1000:1. The effect of accelerating transfer.

(other matters)

In Embodiments 7 and 8, although D2 of the alignment target region of the common electrode is set to a small value, it may be a large value. In addition, although B2 of the alignment target region of the pixel electrode is set to a large value, it will be t-spray alignment due to the influence of the transverse electric field, so even a small value can obtain an effect.

In addition, although the opposing pretilt angle C2 is set at 5 degrees relative to the pretilt angle A2 of 2 degrees on one side of the substrate, if the ratio between the two is large, the transfer time can be shortened and the transfer time can be further accelerated. transfer time.

In addition, in the above description, although the value of the smaller pretilt angle A2 was set at 2 degrees, in order to facilitate the transition to the b-spray alignment, the values of the smaller pretilt angles A2 and D2 The pretilt angles B2 and C2 may be 3 degrees or less, and the large pretilt angles B2 and C2 may be 4 degrees or more.

In addition, although parallel alignment treatment was performed on the orientation treatment direction in the direction at right angles to the signal electrode lines 113 in the same direction as the substrate, it may also be performed in the direction at right angles to the gate electrode lines 114 (that is, for the direction in FIG. 16 ). Parallel orientation treatment is carried out in the same direction as the upper and lower substrates. In this case, the place where disclination lines are formed is different.

In addition, if the direction in which the above-mentioned alignment treatment is performed in parallel is deviated, for example, by about 2 degrees from the perpendicular direction along the electrode line of the pixel electrode, the disclination line formed in the pixel is obliquely directed from the electrode. Since a transverse electric field is applied to the liquid crystal molecules in the spray alignment, a twisting force is added, and it becomes easy to transfer to the bend alignment, and it becomes a liquid crystal display device in which the transfer is fast and reliable.

In addition, as the first voltage, it is sufficient as long as it is higher than a voltage at which disclination lines can be formed. In addition, although the second voltage is applied between the pixel electrode and the common electrode, it may be applied to the common electrode.

In addition, although a polyimide material is used as the above-mentioned alignment film material, other materials such as a monomolecular film material may also be used.

In other liquid crystal display devices, for example, the substrate may also be formed of a plastic substrate. In addition, one of the substrates may be formed of a reflective substrate, for example, formed of silicon.

(Embodiment 9)

This embodiment is an embodiment in which unevenness is formed in a shape that is embedded with signal electrode lines and pixel electrodes, and gate electrode lines and pixel electrodes, respectively.

20 and 21 schematically show key parts of the liquid crystal display device of this embodiment.

This figure is a view of pixels of an active matrix OCB mode liquid crystal display device viewed from above the display surface (user side).

In FIG. 20, 206 is a signal electrode line (bus), 207 is a gate electrode line, and 208 is a switching transistor (device).

In addition, although the signal electrode lines 206 intersect with the gate electrode lines 207 in the drawing, the electrode lines on both sides can be three-dimensionally arranged with an insulating film (not shown) in between as a matter of course.

In addition, a switching transistor 208 formed of a TFT is connected to a substantially square pixel electrode 202a in the figure. In this way, the functions, actions and effects of the signal electrode lines 206, gate electrode lines 207, switching transistors 208, and pixel electrodes 202a are not only different from those in the OCB mode but also from conventional liquid crystal display devices.

In addition, the upper and lower alignment films 203a and 203b have been subjected to alignment treatment using a grinding cross tube or the like in order to initially spray-align the liquid crystal molecules 211, which is also the same as in conventional liquid crystal display devices.

In addition, together with the functions of the polarizers 204a, 204b, etc., all the liquid crystal molecules in the pixel are made to be uniform in the bend alignment region where the liquid crystal molecules change from the spray alignment state in the pixel to the bend alignment state between the facing substrates. The function of shifting is performed to perform bright and dark display, which is also the same as that of conventional liquid crystal display devices.

However, as shown in FIG. 20(a), a convex portion 221a and a convex portion 222a are formed at substantially the center of each side of a substantially square pixel electrode 202a. On the other hand, on the signal electrode line 206 and the gate electrode line 207 arranged close thereto, the protrusions 261, 271 and the recesses 262, 272 are formed so as to fit into the protrusions 221a and 222a. Distorted wiring. For this reason, the horizontal electric field application portion for transfer excitation that is deformed is formed at the upper, lower, left, and right positions of the pixel electrode 202a (on the paper surface in FIG. 20(a)), which is different from conventional liquid crystal display devices. of.

Next, a method of manufacturing the liquid crystal display device will be described.

On the surface of the pixel electrode 202a and the surface of the common electrode 202b provided with a lateral electric field application portion, apply, dry and sinter polyimide of the polyamic acid type produced by Nissan Chemical Industries Co., Ltd. with a pretilt angle of about 5 degrees. Alignment films 203a and 203b are formed on the liquid crystal layer 210 side of the respective electrode surfaces.

Next, the surfaces of the above-mentioned alignment films 203a and 203b are subjected to alignment treatment in a direction substantially perpendicular to the signal electrode lines 206 as shown in FIG. 20( a ) using a grinding cross tube.

Based on the above, a positive nematic liquid crystal material is vacuum-injected between the upper and lower substrates to form the liquid crystal layer 210 .

For this reason, although not shown, on the surfaces of the upper and lower alignment films 203a, 203b, the pretilt angles of the liquid crystal molecules 211 have positive and negative reciprocal values, and the direct axis directions of the molecules are oriented such that they are substantially parallel to each other. , the liquid crystal layer 210 becomes a so-called spray alignment in which liquid crystal molecules spread obliquely in a so-called no-voltage-applied state.

Next, the operation for displaying the liquid crystal display device will be described.

On the basis of the above, while repeatedly applying a pulse-like voltage of -15V, which is a relatively high voltage in the liquid crystal field, between the common electrode 202b and the pixel electrode 202a, the gate electrode line 207 is brought into a normal scanning state or Almost all of them are turned ON. In this way, a lateral electric field stronger than a normal surrounding lateral electric field is applied between the gate electrode line 207, the signal electrode line 206, and the pixel electrode 202a by the lateral electric field applying section. As a result, in the case of polishing in the direction substantially perpendicular to the signal electrode lines 206 in the spray alignment region in the pixel region, the lateral electric field between the gate electrode lines 207 and the pixel electrodes 202a is mainly In the liquid crystal layer 299 where the applied portion is the base point, a transition nucleus for transition to the bend alignment is generated. In addition, as shown in FIG. 21, in the case of polishing in a direction perpendicular to the gate electrode line 207, the liquid crystal layer is mainly polished with the horizontal electric field application portion between the signal electrode line 206 and the pixel electrode 202a as the base point. In 298, a transfer nucleus that transfers to the bend orientation is generated.

Furthermore, based on the transition core, the bend alignment area is expanded, and as a result, the entire pixel area can be transferred to the bend alignment within about 0.5 seconds.

In spite of such a mechanism, it is considered that the liquid crystal layer 210 is in a b-spray alignment state by applying a high voltage between the upper and lower electrodes as shown in FIG. The periphery is high, and a transverse electric field is applied from the transverse electric field application part in a direction substantially at right angles to the alignment state of the liquid crystal molecules (vertical direction of the plane in Figure 20(b)), so the lower direction in the b-spray orientation of Figure 20(b) The liquid crystal molecules on one side of the substrate are subject to twisting force, which is due to the occurrence of transfer nuclei.

In the above description, although the lateral electric field applying portion is formed by embedding the unevenly deformed pixel electrode portion and the uneven portion of the signal electrode lines on both sides, as shown in FIG. The pixel electrodes 202a are formed only on the signal electrode lines 206 and only on the gate electrode lines 207 .

That is, in this figure, the convex portion 263 of the signal electrode line 206, the convex portion 273 of the gate electrode line 207, and the convex portions 223a and 2024a of the pixel electrode 202a are only located in any one of them, and are not embedded in each other. One point is different from the situation shown in FIG. 20 .

In addition, the planar shape of the concavo-convex portion may of course be other than the triangle and quadrangle shown in FIGS.

In addition, in Fig. 20 to Fig. 22, although the lateral electric field applying part is provided at a total of 4 places up, down, left, and right of a pixel, depending on the size of the pixel, only two up and down or only one may be provided. In addition, it is of course also possible to form irregularities continuously along the edge of the electrode. In addition, although the polishing direction has been set to be substantially perpendicular to the signal electrode lines or the gate electrode lines, the polishing direction may be set to be oblique. In this case, the transition from the liquid crystal layer to the bend orientation will occur at the portion where the lateral electric field is applied between the signal electrode line and the gate electrode line. In addition, it is desirable to arrange at least one lateral electric field applying portion capable of applying a lateral electric field in a direction substantially perpendicular to the polishing direction in a pixel unit.

In addition, since Fig. 20 to Fig. 22 are plan views, although the two electrode lines (signal electrode lines 206 and gate electrode lines 207) and the pixel electrode 202a can be regarded as being in the same plane, at least the far electrode lines, It is arranged on the array substrate at a height different from that of the pixel electrodes.

As described above, the lateral electric field application portion composed of the electrode deformation portion that deforms a part of the periphery of the pixel electrode in a concave-convex manner in a plane parallel to the substrate surface is separated by about 0.5 to 10 microns in plan view. The existence of the convex portion of the signal electrode line or the gate electrode line or the concave portion depressed by about 0.5 to 10 microns on the side of the lateral electric field application portion generates a lateral electric field.

(Embodiment 10)

In this embodiment, electrode lines for applying a transverse electric field are provided.

Hereinafter, this embodiment will be described with reference to FIG. 23 .

(a) of this figure is a plan view seen from the top of the substrate. (b) is a cross-sectional view cut along a plane parallel to the gate electrode line 207 of the liquid crystal display device.

In (a) and (b) of this figure, 209 is an electric wire dedicated to applying a transverse electric field that is laid on the substantially directly lower portion of the signal electrode line 206 on the array substrate 201a. 212 is a transparent insulating film for insulating the above-mentioned horizontal electric field applying line 209 from the signal electrode line 206, the gate electrode line 207, and the like. Therefore, when viewed from above (the user's side direction perpendicular to the display surface), as shown in FIG. The portion 291 protrudes to the side of the signal electrode line 206 . In addition, the above-mentioned signal electrode lines 206 and pixel electrodes 202a are not any different from the corresponding parts of the prior art.

The above-mentioned lateral electric field applying part 209 is connected to the drive circuit that has connected the above-mentioned signal electrode lines 206 or gate electrode lines 207. In addition, the above-mentioned lateral electric field applying part 209 is configured as a normal liquid crystal after orientation transfer. When displayed, disconnect the drive circuit.

In addition, the above-mentioned transverse electric field application line 209 is used as the signal electrode line on the upper part of the signal electrode line 206, and is arranged close to the pixel electrode with a transparent insulating film in the middle, so as to increase the effect of transverse electric field application. Contact holes not shown in the insulating film are electrically connected. In this case, since there are two signal electrode lines, there is an effect of increasing redundancy and reducing resistance.

That is, as shown in FIG. 23(c), the transverse electric field applying line 209a is provided directly on the signal electrode line 206 with the transparent insulating film 213 interposed therebetween. The same applies to the convex portion 291a having a triangular planar view at the central portion of the pixel.

In addition, Fig. 23(d) is another example of this embodiment. As shown in the figure, the horizontal electric field application line 209b is covered by a planarized transparent insulating film 212b. In addition, the signal electrode line 206 is covered by a planarized transparent insulating film 212c under the dedicated line 209b. The pixel electrode 202a is arranged on the above-mentioned on the transparent insulating film 212b. The same applies to the convex portion 291b having a triangular shape in plan view at the central portion of the pixel.

In addition, in the drawing, although the convex portion of the dedicated line for applying the transverse electric field is made into a triangular shape, it is also possible to provide the convex portion continuously on the entire portion facing the pixel electrode, or to have a convex portion protruding upward. It is self-evident that the three-dimensional structure of the convex part etc. is.

In addition, instead of the signal electrode lines, dedicated lines for applying a lateral electric field may be provided directly below or directly above the gate electrode lines.

(Embodiment 11)

In this embodiment, at least one notch is provided in the pixel electrode to form a defective portion.

FIG. 24 schematically shows aspects and features of a pixel unit of the liquid crystal display device of this embodiment. As shown in this figure, the pixel electrode 202a made of the ITO film is removed by etching to form an electrode defect portion 225 having a crankshaft shape with a width of several micrometers in plan view.

In addition, on the surface of the pixel electrode 202a having the electrode defect portion 225 and the surface of the common electrode not shown, a polyamic acid type polyamic acid pre-tilt of about 5 degrees produced by Nissan Chemical Industries Co., Ltd. is applied, dried and fired. Alignment films (not shown) are formed on the corner polyimide alignment film materials, and then the surface is oriented in a direction perpendicular to the grid electrode lines 207 with a grinding cross tube. For this reason, the pretilt angles of the liquid crystal molecules have positive and negative reciprocal values, and are aligned in parallel in the same direction so as to be substantially parallel to each other, which is the same as in Embodiments 9 and 10.

Therefore, the liquid crystal layer forms a so-called spray-aligned liquid crystal cell composed of an alignment region in which liquid crystal molecules spread obliquely in a so-called no-voltage-applied state.

However, when repeatedly applying a voltage pulse of 15V or -15V to the common electrode between the common electrode and the pixel electrode before displaying, the gate electrode is turned into a normal scanning state or an almost completely ON state. Since there is an electrode defect portion 225 in the pixel unit, as shown in FIG. 24( b ), a strong distorted oblique transverse electric field 280 will be generated at the edge of the electrode defect portion 225 .

For this reason, in the spray alignment in the pixel region, the transfer nucleus to the bend alignment transfer will take place in the liquid crystal layer 299 of the electrode defect portion 225, and the bend alignment region is further expanded so that the entire pixel region completes the alignment in about 0.5 seconds. Shift in bend orientation.

This is because a strong transverse electric field is received in the transverse electric field application portion constituted by the electrode defect portion 225, and the liquid crystal molecules in the vicinity thereof are arranged in a horizontal state on the substrate surface, becoming a so-called b-spray alignment state, and distorted energy It becomes higher than the surrounding area, and since the voltage is applied between the upper and lower electrodes based on this state, more energy is supplied, and as a result, transition nuclei are generated in the electrode defect portion 225, and the bending orientation area expands.

In addition, in FIG. 24 , although one electrode defect portion 225 is formed in the shape of a crank when viewed from above, it is of course possible to form two or more.

In addition, as for the shape thereof, it goes without saying that a straight line, a rectangle or a circle, an ellipse, and a triangle shape are also possible.

In addition, the electrode defect portion 225 may also be formed on the common electrode side.

In addition, it is of course possible to form both the pixel electrode and the common electrode.

(Embodiment 12)

In this embodiment, regions with different inclination angles are previously formed in the pixel plane together with the generation of the transverse electric field.

FIG. 25 schematically shows the structure and features of a pixel unit of the liquid crystal display device of this embodiment. (a) of this figure is a cross-sectional view of a pixel in a direction parallel to the gate electrode line. It is the same pixel, but the inclination angle is shown at (I) on the left and (II) on the right. different scenarios.

Fig. 25 (b) is a plan view of the pixel viewed from the upper (user side) direction, and concave-convex portions 221a, 222a are provided on the upper, lower, left, and right sides of the pixel electrode 202a. In addition, concave-convex portions 261, 262, 271, 272, so that the corresponding positions of the signal electrode line 206 and the gate electrode line 207 are embedded with the above-mentioned concave-convex parts 221a, 222a. Like the above-mentioned embodiment 7, 2.5V as the first voltage is applied, and the A disclination line 226 is formed at the boundary of (I) and (II) in FIG. 25( a ).

Hereinafter, a method for manufacturing the liquid crystal display device of the present embodiment will be described.

Alignment films 203am, 203bm are respectively formed on the inner faces of the opposite substrates of the active matrix liquid crystal unit. The alignment films 203am, 203bm have been subjected to spray alignment in the state of no voltage application, and are formed on the pixel electrodes. 202a or the gate electrode line 207, etc., which are wired close to it, is the same as that of the previous first embodiment.

However, the treatment of the alignment film is different. That is, in FIG. 25(a), on the surface of the pixel electrode 202a having a lateral electric field application portion, the polyamic acid type produced by Nissan Chemical Industries Co., Ltd. has a large value of about 5 degrees by coating, drying and firing. The polyimide material with the pretilt angle B2 forms the alignment film 203am.

Next, ultraviolet rays are irradiated only to the left side region 203ah of the alignment film 203am, that is, only in the direction shown in (I), so as to change it into an alignment film whose pretilt angle E2 is as small as about 2 degrees. .

In this regard, on the opposite substrate 201b, the polyimide material of the polyamic acid type produced by Nissan Chemical Industries Co., Ltd. with a pretilt angle F2 of about 5 degrees is coated and dried, and the common electrode 202b is formed. On, an alignment film 203bh is formed.

Next, ultraviolet rays are irradiated only to the right side region 203bm of the alignment film 203bh, that is, only in the direction shown in (II), so as to change it into an alignment film whose pretilt angle D2 is as small as about 2 degrees. .

In this way, as shown in (I) of FIG. 25(a), the left half of the alignment film 203ah on the array substrate 201a side is aligned with the small value of the pretilt angle E2. The large value of the pretilt angle F2 of the film 203bh, as shown in (II) of FIG. A small value of the pretilt angle D2 of the alignment film 203bm on one side and the right half.

In addition, as shown in FIG. 25( b ), as shown in FIG. 25( b ), the surfaces of the alignment films formed with different pretilt angles from each other have the same upper and lower substrates in the direction substantially perpendicular to the signal electrode 6 . Orientation in parallel. Then, a positive nematic liquid crystal material is filled, and a liquid crystal layer 210 made of it is arranged.

On the basis of the above, the small pretilt angle E2 is arranged on the orientation source (the fundamental direction of grinding) of the pixel electrode 202a, and the pretilt angle F2 with a large value is arranged on the side opposite to the pretilt angle E2 , in the region represented by (I) of the pixel in FIG. In the indicated region, it is easy to form the t-spray alignment 227t that aligns the liquid crystal molecules on the upper substrate side.

Next, when 2.5V near the transition threshold voltage is applied between the opposite electrodes of the switching transistor 208 of the liquid crystal cell, for the above-mentioned reason, a b-spray alignment region and a t-spray alignment region are formed in the same pixel, On the boundary thereof, disclination lines 226 are clearly formed along the signal electrode lines 206 and across the gate electrode lines 207 .

A pulse of -15V was repeatedly applied between the common electrode of the pixel and the pixel electrode. In this way, as shown in FIG. 25(b), transfer nuclei are generated from the disclination line 226 and the liquid crystal layer 299 near the portion where the transverse electric field is applied, and the transfer expands to the bend alignment region, and it takes about 1 second in all TFT panel pixels. Quickly transfer within.

It is considered that this is because in the disclination line 226 region which is the boundary of the b-spray orientation region and the t-spray orientation region, the energy of the distortion becomes higher than that of the surroundings, and in addition to this state, by means of The generated transverse electric field distorts the spray orientation, thus making the transfer easier, and because a high voltage is applied between the upper and lower electrodes to provide more energy for the transfer.

In the above, although the present invention has been described based on several embodiments, the present invention is of course not limited by these in any way. That is, for example, it may be as follows.

1) Make the voltage applied between the pixel electrode and the common electrode a continuous or intermittent voltage.

2) In the case of repeated application of high voltage pulses, the frequency of which is in the range from 0.1 Hz to 100 Hz, and the duty ratio of the second voltage is at least in the range of 1:1 to 1000:1, select the accelerated transition value.

3) The substrate to be used is made of plastic, and an organic conductive film is used as an electrode.

4) One side of the substrate is formed by a reflective substrate, for example, one substrate is formed by a reflective electrode made of silicon or aluminum or the like, and a reflective liquid crystal display device is made.

5) At the same time, a method of providing a protrusion for generating a strong electrode electric field in a direction perpendicular to the substrate surface is used on the common electrode.

6) Using spherical glass or silicon dioxide to keep the gap between the two substrates constant, forming protrusions required for this purpose, and providing the protrusions with a function of aligning liquid crystal molecules.

7) Make the upper part or the lower part of the above-mentioned protrusion part also serve as the above-mentioned protrusion for generating the strong electrode electric field.

8) The shape of the pixel electrode is made into a rectangle or a triangle instead of a square.

9) The pixel is divided into three or four regions instead of two regions in which the alignment of the liquid crystal is different.

10) In order to give a magnitude to the pretilt angle, a method of changing the surface state with an O2 asher or the like and forming an alignment film on the transparent electrode is adopted.

(Embodiment 13)

FIG. 26 is an external view showing the configuration of a test cell used in the study of the spray-bending transition time of the liquid crystal display device of the present invention, and FIGS. 27 and 28 are for explaining a part of the manufacturing process for forming protrusions.

On the glass substrate 308, a PC-based photoresist material produced by JSR Co., Ltd. was applied to form a photoresist film with a thickness of 1 micrometer. Next, the photoresist film 320 is irradiated and exposed with parallel light ultraviolet rays 323 through the photomask 321 provided with the openings 322 of a rectangular pattern. The above-mentioned photoresist film 320 exposed to parallel light was developed, rinsed, and pre-hardened at 90° C., as shown in FIG. 28 , to form a shape object 310 with a convex cross-section.

Next, an ITO electrode 7 with a thickness of 2000 Å was formed on the above-mentioned substrate according to a predetermined method, and a glass substrate 308 with electrodes was produced. Then, with the spin coating method, on the glass substrate 301 with the transparent electrode 302 and the glass substrate 308 on which the above-mentioned protrusions have been formed, the alignment film SE-7492 produced by Nissan Chemical Industry is coated, and carried out in a constant temperature bath. Curing at 180° C. for 1 hour forms the alignment films 303 and 306 . Then, the abrasive cloth made of rayon is rubbed in the direction shown in FIG. Resin (trade name)) was pasted so that the distance between the substrates became 6.5 micrometers, and a liquid crystal cell 309 (referred to as a liquid crystal cell A) was produced.

At this time, rubbing treatment is performed so that the liquid crystal pretilt angle at the interface of the alignment film becomes about 5 degrees.

Next, a liquid crystal MJ96435 (refractive index anisotropy Δn=0.138) was injected into the liquid crystal cell A by a vacuum injection method to prepare a test cell A.

Next, paste the polarizer on the test unit A so that its polarization axis is at an angle of 45 degrees to the rubbing treatment direction of the alignment film, and make the polarization axes of each other perpendicular to each other, add a square wave of 7V, and observe Transition to the bend orientation, it was found that the entire electrode area transitioned from the spray orientation to the bend orientation within approximately 5 seconds.

In the region where the protrusions 310 are formed, the thickness of the liquid crystal layer is smaller than that of the surrounding liquid crystal layer region, and the effective electric field intensity is large, and the bending transition reliably occurs from this portion. The resulting bend orientation rapidly spreads to other regions.

That is, reliable and high-speed jet-bend transfer can be performed.

The cross-sectional shape of the convexity is as shown in the present embodiment, but of course not a rectangular shape, but also a trapezoidal shape, a triangular shape, and a semicircular shape are also possible.

As a comparative example, except for using a glass substrate with a transparent electrode without protrusions 310 , a spray alignment unit R was produced by the same process, and liquid crystal MJ96435 was sealed to produce a test unit R. When a 7V square wave is applied to the test unit R, it takes 42 seconds for the entire electrode area to transfer from the spray orientation to the bending area, and the effect of the present invention is obvious.

(Embodiment 14)

FIG. 30 is an external view showing the configuration of a test cell used in the study of the spray-bending transition time of the liquid crystal display device of the present invention, and FIG. 31 is a plan view thereof. Fig. 30 is a cross-sectional view viewed from the line X1-X1 in Fig. 31 . The fourteenth embodiment is characterized in that protrusions 310 are provided on transparent electrodes 307a formed outside the display pixel area. Hereinafter, the production procedure thereof will be described.

Using the spin coating method, on the glass substrate 301 with the transparent electrode 302 and the glass substrate 308 on which the above-mentioned protrusions have been formed, apply the alignment film SE-7492 produced by Nissan Chemical Industry, and carry out 180 ° C in a constant temperature bath. , hardening for 1 hour to form alignment films 303, 306, 306a. Then, the abrasive cloth made of rayon is rubbed in the direction shown in FIG. Resin (trade name)) was pasted so that the distance between the substrates became 6.5 micrometers, and a liquid crystal cell 309 was produced (referred to as a liquid crystal cell B). At this time, rubbing treatment is performed so that the liquid crystal pretilt angle at the interface of the alignment film becomes about 5 degrees.

Next, a liquid crystal MJ96435 (refractive index anisotropy Δn=0.138) was injected into the liquid crystal cell B by a vacuum injection method to prepare a test cell B. Next, paste the polarizer on the test unit B so that its polarization axis is at an angle of 45 degrees to the rubbing treatment direction of the alignment film, and make the polarization axes of each other perpendicular to each other, add a square wave of 7V, and observe Transition to the bend orientation, it is known that the entire electrode area transitions from the spray orientation to the bend orientation within about 7 seconds.

In this embodiment, although the protrusions are provided outside the display pixel area to generate transition nuclei outside the display pixel area, it has been confirmed that the generated bend orientation rapidly moves from the outside of the display pixel area to the display pixel area. The region expands to other regions.

There is a region where no electric field is applied (with no electrode portion) between the display pixel region and the bend nucleus generating electrode region, but as long as it is a minute region, the bend alignment spreads across this region.

(Embodiment 15)

Fig. 32 is an external view showing the configuration of a test unit used in the study of the spray-bending transition time of the liquid crystal display device of the present invention, and Fig. 27, Fig. 28 and Fig. 33 are a part of the manufacturing process for explaining the manufacture of convex objects .

A PC-based photoresist material produced by JSR Corporation was coated on the glass substrate 308 to form a photoresist film with a thickness of 1 micron. Next, the photoresist film 320 is irradiated and exposed with parallel light ultraviolet rays 323 through the photomask 321 provided with the openings 322 of a rectangular pattern. The above-mentioned photoresist film 320 exposed to parallel light was developed, rinsed, and pre-hardened at 90° C., as shown in FIG. 28 , to form a shape object 310 with a convex cross-section.

Next, the following process is used to manufacture: the above-mentioned photoresist film material is above the glass transition point of 150 ° C. After hardening, the shoulders of the protrusions 310 are gently and positively inclined, as shown in FIG. 32, "mountain ” to form its cross-sectional shape.

Next, an ITO electrode 7 with a thickness of 2000 Å was formed on the above-mentioned substrate according to a predetermined method, and a glass substrate 308 with electrodes was produced. Then, with the spin coating method, on the glass substrate 301 with the transparent electrode 302 and the glass substrate 308 on which the above-mentioned protrusions have been formed, the alignment film SE-7492 produced by Nissan Chemical Industry is coated, and carried out in a constant temperature bath. Curing at 180° C. for 1 hour forms the alignment films 303 and 306 . Then, the abrasive cloth made of rayon is rubbed in the direction shown in FIG. Resin (trade name)) was pasted so that the distance between the substrates became 6.5 μm, and a liquid crystal cell 309 (referred to as a liquid crystal cell C) was fabricated.

At this time, rubbing treatment is performed so that the liquid crystal pretilt angle at the interface of the alignment film becomes about 5 degrees.

Next, a liquid crystal MJ96435 (refractive index anisotropy Δn=0.138) was injected into the liquid crystal cell C by a vacuum injection method to prepare a test cell C.

Next, paste the polarizer on the test unit C, so that its polarization axis is at an angle of 45 degrees to the rubbing treatment direction of the alignment film, and make the polarization axes of each other perpendicular to each other, add a square wave of 7V, and observe the direction from the spray orientation Transfer of the bend orientation, it is known that the entire electrode area transfers from the spray orientation to the bend orientation within approximately 7 seconds.

In this test unit C, concentration of an electric field occurs at the tip of the above-mentioned triangle, and bend orientation occurs from this portion. In addition, in the upper part of the triangular shape 60, since there are upper and lower rubbed parts by the rubbing process, as a result, a region where the sign of the liquid crystal pretilt angle is opposite is formed. That is, the liquid crystal director is parallel to the substrate surface in the vicinity of the above-mentioned convex portion, and this state is also considered to contribute to the high-speed spray-bend transfer.

In this embodiment, although the electric field concentration portion is provided inside the pixel area, the same effect can be obtained even if it is provided outside the pixel area. In addition, in the present embodiment, although the electric field concentration portion is arranged only on one side of the substrate, it may of course be arranged on both sides of the substrate.

(Embodiment 16)

FIG. 34 is an external view showing the configuration of a test cell used in the study of the spray-bending transition time of the liquid crystal display device of the present invention, and FIG. 35 shows the electrode pattern of the glass substrate 302 used in this embodiment.

On the two glass substrates 301, 308 of the transparent electrode 302 with the opening 380 and the transparent electrode 307 without the opening, use the spin coating method to coat the alignment film SE-7492 produced by Nissan Chemical Industry. Curing was performed at 180° C. for 1 hour in a constant temperature bath to form alignment films 303 and 306 . Then, the abrasive cloth made of rayon was rubbed in the direction shown in FIG. (trade name of the resin) was pasted so that the distance between the substrates was 6.5 micrometers, and a liquid crystal cell 309 was produced (referred to as a liquid crystal cell D).

At this time, rubbing treatment is performed so that the liquid crystal pretilt angle at the interface of the alignment film becomes about 5 degrees.

Next, a liquid crystal MJ96435 (refractive index anisotropy Δn=0.138) was injected into the liquid crystal cell D by a vacuum injection method to prepare a test cell D.

Next, the polarization axis was made to form an angle of 45 degrees with the rubbing treatment direction of the alignment film, and the polarization axes were perpendicular to each other, and the transition from splay alignment to bend alignment was observed while applying a voltage.

In this test cell D, when a 2V, 30Hz square wave is applied to the electrode on the glass substrate 308 side, and a 7V, 30Hz square wave is applied to the electrode on the glass substrate 301 side, the entire electrode area shifts from the spray alignment to the bend alignment The time required is 5 seconds, realizing extremely high-speed bending transfer.

In this embodiment, although an electric field of 5V (=7V-2V) is applied to the two liquid crystal layers sandwiched between the electrodes, the liquid crystal layer at the opening of the electrodes becomes 7V (=7V-0V) as a result. ) of the effective electric field, so with the help of this, bend orientation will occur.

In this embodiment, although the shape of the opening is rectangular, it is of course possible to have a circular, triangular, etc. shape.

(Embodiment 17)

Fig. 36 is a sectional view of essential parts of the liquid crystal display device of Embodiment 17, and Fig. 37 is a partially enlarged view thereof. In this liquid crystal display device, a pixel switching device 380, signal electrode lines 381, and gate signal lines (not shown) are formed on a glass substrate 308, and these switching devices 380, signal electrode lines 381 and gate signal lines are covered. A planarization film 382 is formed. Then, the display electrode 307 is formed on the planarizing film 382 , and the display electrode 307 is electrically connected to the switching device 380 through the relay electrode 384 inserted into the contact hole 383 opened in the planarizing film 382 . The portion of the relay electrode 384 on the upper opening side of the contact hole 383 forms a concave portion 384a as shown in FIG. 37 . As a result, an opening can be formed in the display electrode 307 by means of the concave portion 384a, and the concentration of the electric field can be generated in the vicinity of the concave portion 384a. Therefore, shortening of transfer time can be achieved.

(Embodiment 18)

Fig. 38 is an external view showing the configuration of the liquid crystal display device of the present invention.

With the arrangement shown in Fig. 39, phase difference plates 312, 315 composed of optical media with negative refractive index anisotropy arranged in a mixed manner, negative uniaxial phase difference plates 311, 314, positive uniaxial The phase difference plate 319 and the polarizers 313 and 316 are pasted together to form a liquid crystal display device D.

At this time, the optical path difference values of the phase difference plates 312, 315, 311, 314, and 319 are 26 nm, 26 nm, 350 nm, 350 nm, and 150 nm for light with a wavelength of 550 nm, respectively.

FIG. 40 is a voltage-transmittance characteristic at the front surface of the liquid crystal display device D at 25°C. After applying a square wave of 10 V for 10 seconds and confirming the orientation, measurement was performed while the voltage was lowered. In this liquid crystal display device, since 2.1V is used to cause transition from bend alignment to spray alignment, it is practically necessary to use a voltage of 2.2V or higher for display.

Secondly, the viewing angle dependence of the contrast when the white level voltage is set to 2.2V and the black level voltage is set to 7.2V has been determined. It has been confirmed that within the range of 126 degrees up and down and 160 degrees left and right, the contrast ratio of If the ratio is more than 10:1, sufficient viewing angle characteristics can be maintained even if the orientation of the liquid crystal guide dipole is partially arranged on the surface of the substrate alignment film, which is different from the surrounding area. In addition, no defect in display quality was found even by visual observation.

In addition, the response time between 3V and 5V was measured, and it was found that the rising time was 5 milliseconds, and the falling time was 5 milliseconds.

It can be seen from the above description that the liquid crystal display device of the present invention can realize high-speed spray-bend alignment transfer without sacrificing the wide viewing angle characteristics or response characteristics of the existing OCB mode, and thus has great practical value.

(Embodiment 19)

Fig. 41 is a sectional view of key parts of a liquid crystal display device according to Embodiment 19, and Fig. 41(a) is a schematic view showing the orientation in the initial state without application of an electric field. A liquid crystal cell operating as a bend alignment type cell is a so-called sandwich structure cell in which a liquid crystal layer 402 is sealed between two parallel substrates 400 and 401 . Usually, a transparent electrode is formed on one substrate, and a pixel electrode including a thin film transistor is formed on the other substrate.

Fig. 41(a) is a schematic diagram showing the orientation in the initial state without application of an electric field. The orientation in the initial state is a state in which the molecular axes of the liquid crystal molecules are slightly inclined with respect to the plane of the substrates 400 and 401 , and are substantially parallel and substantially uniformly aligned. That is to say, it is uniformly oriented. The liquid crystal molecules present at the interface with the substrates are inclined in opposite directions to each other in both the upper and lower substrates 400 , 401 . That is, the orientation angles θ1 and θ2 (that is, pretilt angles) of the liquid crystal molecules existing on the interface with the substrate are adjusted so as to have different signs from each other. In addition, in the following description, the orientation angle and the pretilt angle are angles indicating the inclination of the molecular axes of the liquid crystal molecules with respect to the plane parallel to the substrate, with anticlockwise rotation as positive based on the plane parallel to the substrate.

When the liquid crystal layer 402 in the state of Fig. 41(a) is applied with an electric field exceeding a certain value in the vertical direction to the substrate plane, the alignment state of the liquid crystal changes to the state shown in Fig. 41(b). That orientation shifts.

The orientation shown in Fig. 41(b) is called bend orientation. The inclination of the molecular axes of the liquid crystal molecules to the substrate plane near the two substrate surfaces, that is, the absolute value of the orientation angle becomes smaller, and the absolute value of the orientation angle of the liquid crystal molecules becomes larger at the central portion of the liquid crystal layer 402 . In addition, there is substantially no twisted structure over the entire liquid crystal layer.

When such a transition from uniform alignment to bend alignment is observed in detail, first, in a part of the liquid crystal layer 402, bend alignment nuclei are formed, and the nuclei slowly encroach on other regions that are uniformly aligned. It grows slowly, and eventually the entire liquid crystal layer becomes a bend orientation. In other words, the transition of the liquid crystal layer to the bend orientation and the generation of nuclei, that is, the transition from the uniform orientation in a minute region to the bend orientation, are necessary.

Therefore, the inventors of the present invention solved the equation of motion of the unit vector of liquid crystal molecular orientation (hereinafter referred to as "direction dipole"), analyzed the transition to the bend orientation in a small region, and found the core conditions that can easily occur. Hereinafter, the method thereof will be described.

The alignment state of liquid crystals can be expressed by directing dipoles. In addition, the guide dipole n is a function that can be represented by [Equation 1].

n(x)=(n _x (x, y, z), n _y (x, y, z), n _z (x, y, z)) (Formula 1)

The free energy density f of the liquid crystal can be expressed as a function of the director n as expressed by [Equation 2].

f＝{k ₁₁ (divn) ² +k ₂₂ (n×rotn) ² +k ₃₃ (n×rotn) ² }Δ∈(E·n) ² (Formula 2)

Among them, k11, k22, and k33 are Frank's elastic constants, respectively representing the elastic constants of spraying, twisting, and bending. Δε represents the difference between the permittivity in the direction of the molecular axis of the liquid crystal and the permittivity in the direction perpendicular thereto, and means the permittivity anisotropy. Also, E is the external electric field.

In [Formula 2], the 1st term, the 2nd term, and the 3rd term represent the elastic energy by expansion, twist, and bending of a liquid crystal, respectively. In addition, item 4 represents electric energy generated by electric interaction between an external electric field and liquid crystal. If Δε>0, the electric energy becomes minimum when n becomes parallel to E, and if Δε<0, then electric energy becomes minimum when n is perpendicular to E. Therefore, when an electric field E exceeding a certain intensity is applied, if Δε>0, the liquid crystal molecules are oriented so that the long axis of the molecule becomes parallel to the direction of the electric field, and if Δε<0, the liquid crystal molecules are oriented so that the molecular length The axis is perpendicular to the direction of the electric field.

The full free energy F of the liquid crystal when the molecular orientation in the initial state is subjected to deformation induced by an external electric field can be expressed as the volume integral of f.

F＝∫f(n(x))dx (Formula 3)

As shown in [Equation 3], the total free energy F is a function defined as a variable by an unknown function n(x) representing a guided dipole (that is, a generic function). The alignment state of the liquid crystal that appears when an external electric field is applied can be expressed by n(x) that minimizes F under appropriate boundary conditions. That is, if n(x) that minimizes the total free energy is determined, the alignment state of the liquid crystal can be predicted. In addition, if the guide dipole n(x, t) that minimizes F under appropriate boundary conditions can be determined taking time variations into consideration, all behaviors of devices such as optical constants can be predicted. Physically, this is a typical principle of minimum action, and mathematically, it is a variational minimum problem near the boundary value.

Therefore, [Equation 3] is solved in principle. However, if an analytical method such as Euler's equation is used, for example, complex nonlinear equations will appear, so it is difficult to simply determine the functional expression of the guiding dipole n(x).

Therefore, in order to easily solve [Equation 3], the following method is employed. First, the integral space is discretized by the same method as the finite element method. That is to say, express [Equation 3] as the integral sum of each element with np elements in the whole integral space.

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; v</span>}}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dx</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; np</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dx</span>}$

(Formula 4)

Here, the following approximation is performed for the guide dipole n(x) in the partial integration space ΔV. As shown in [Equation 2], although nx, ny, and nz are originally functions of x, y, and z, they are assumed to be constant in ΔV. Also, it is approximated as dnx,j/dx=(nx,j+1-dnx,j)/Δx. In addition, nx,j is nx in the J-th element, and as described above, is constant in ΔV, but is unknown. Although the approximation of n(x) in this part of the integral space ΔV is a rough approximation, the approximation can be improved by subdividing the integral space and covering it.

If the above approximation is adopted, since nx, j, ny, j, nz, j are constants in one element in [Formula 4], the integral itself can be easily calculated. However, even at this stage, the formula representing the total free energy F still has multiple unknowns nx, j, ny, j, nz, j high-order terms and nonlinear terms proportional to the division number, which is still complicated of. However, the values of nx, 0, ny, 0, nz, 0 etc. can be easily given as boundary conditions.

If the above approximation is used, the total free energy F is transformed into

F=F(n _xj , n _yj , n _zj ) (0≤j≤np-1)

(Formula 5)

That is to say, the total free energy F is transformed from a functional function defined by the unknown n(x) as a variable into a function of the unknown nx, j, ny, j, nz, j. The unknowns nx, j, ny, j, nz, j are values that minimize the function F within the multidimensional parameters.

As mentioned above, the bend orientation of liquid crystal has a structure that does not substantially have a twist, and as described above, the director n can be expressed as a function of orientation angle although it is originally a function of x, y, and z. In this case, the director dipole n in the bend orientation can be expressed by

n(cosθ, 0, sinθ)

(Formula 6)

However, θ is an inclination of the liquid crystal molecules with respect to a plane parallel to the substrate, that is, an orientation angle. In addition, it is stipulated that θ depends only on the distance z of the liquid crystal molecules from the substrate. The schematic diagram of Fig. 42 shows the guiding dipole.

Substitute [Equation 6] into [Equation 4], discretize np elements, and obtain θj that minimizes F for each element. That is, θj satisfying the following equation is obtained for each element.

$\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; d\&theta;j</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}}{{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \{</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="A20051011419300761.png,A20051011419300791.png"\; state="\{\{state\}\}">sin</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}$

$<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="cos"\; filenames="A20051011419300761.png,A20051011419300791.png"\; state="\{\{state\}\}">cos</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="33"\; label="k"\; filenames="A20051011419300741.png"\; state="\{\{state\}\}">k</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="cos"\; filenames="A20051011419300761.png,A20051011419300791.png"\; state="\{\{state\}\}">cos</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="33"\; label="k"\; filenames="A20051011419300741.png"\; state="\{\{state\}\}">k</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;\&epsiv;</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; E</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="A20051011419300761.png,A20051011419300791.png"\; state="\{\{state\}\}">sin</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; \}</span>$

(Formula 7)

In addition, d is L/np, and L is the distance between substrates.

However, it is not easy to solve np complicated nonlinear equations like [Equation 7] simultaneously. Therefore, [Equation 7] is solved by performing circuit analogy as follows. The equation of motion of the guided dipole can be expressed by the following formula.

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}\frac{{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; +</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; d\&theta;j</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}$

(Formula 8)

In addition, η is a viscosity coefficient of liquid crystal. For [Equation 8], the following circuit analogy is performed.

η→C

θ _i →V _j (Equation 9)

[Equation 8] is transformed into

$\mathrm{<span\; class="notranslate">\; C</span>}\frac{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; np</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

(Formula 10)

The circuit corresponding to [Expression 10] is constituted by np CR circuits as shown in FIG. 43 . The second term of [Formula 10] represents the current flowing in the CR circuit. In addition, Rj is a resistor for relaxing discharge, and is a voltage control resistor that defines the current (i) flowing in the CR circuit as i=F(Vj)V.

The current i (=F/Vj) converges to 0 with a specific Vj. That is, if the voltage at which the current flowing in the CR circuit becomes zero can be obtained using a circuit simulator, then Vj can be obtained automatically.

As mentioned above, by replacing the motion equation of the guided dipole with the equivalent circuit, the nonlinear simultaneous equations representing the orientation phenomenon of the liquid crystal can be analyzed on the circuit simulator, and the external electric field E and orientation can be obtained. Relationship between states (orientation angle θj).

In the above-mentioned method, since the nonlinear simultaneous equations representing the orientation phenomenon are replaced with circuits and analyzed on the circuit simulator by means of circuit analogy, only the equivalent circuit is set in the program, and the equation used to solve the equation is not included. own calculation program. Therefore, it is possible to simplify and downsize the program.

In addition, if the change of the orientation angle θj accompanying the increase of the external electric field E is calculated according to the above method, the critical electric field Ec of liquid crystal transition can be obtained as the external electric field E when the orientation angle θj suddenly changes.

FIG. 44 is an example of calculation results based on the above-mentioned method, and shows temporal changes in θj when the external electric field is increased over time. In addition, the results in Fig. 44 are carried out by fixing the boundary conditions as θ0=+0.1rad, θnp-1=-0.1rad, setting k11=6×10 ^-7 dyn, k33=12×10 ^-7 dyn, Δε=10 The result of the calculation. As shown in FIG. 44 , it was found that at the initial stage of application of the electric field, the orientation angle θj was small, and the orientation state of the liquid crystal was uniformly aligned. However, after a certain period of time, that is to say, when the external electric field E exceeds a certain value (E>Ec), a transition will occur due to a sudden change in the orientation angle θj. The absolute value of the orientation angle θj after the transfer increases from the vicinity of the two substrates toward the center of the liquid crystal layer, which indicates that the orientation state of the liquid crystal after the transfer is a bend orientation.

The smaller the critical electric field Ec is, the faster the alignment state of the liquid crystal can be transferred from the uniform alignment to the bend alignment. Then, the conditions for determining the orientation of liquid crystals were varied in various ways according to the method described above, and the critical electric field Ec under the various conditions was calculated. As a result, it was found that the critical electric field Ec is particularly affected by the elastic coefficient (spray elastic coefficient) of the liquid crystal and the asymmetry of the pretilt angle.

FIG. 45 shows the results of solving the relationship between the ejection elastic coefficient k11 and the critical electric field Ec. In addition, Fig. 45 shows the calculation results by setting the boundary conditions as θ0=+0.1rad, θnp-1=-0.1rad, k33=12×10 ^-7 dyn, and Δε=10. As shown in FIG. 5 , the larger the ejection elastic coefficient k11 is, the larger the critical electric field Ec is. Especially in the range of k11>10×10 ^-7 dyn, Ec will increase sharply with the increase of k11.

Therefore, in order to achieve rapid liquid crystal transfer, it is effective to make the ejection elastic coefficient k11 less than 10×10 ^-7 dyn, preferably less than 8×10 ^-7 dyn. In addition, the lower limit of the ejection modulus k11 is not particularly limited, but it is ideally set at 6×10 ^-7 dyn or more, because it is usually difficult to synthesize or prepare a liquid crystal material with k11<6×10 ^-7 dyn .

There are no particular limitations on the liquid crystal material having the above-mentioned ejection modulus k11, and examples thereof include pyrimidine-based liquid crystals, dioxane-based liquid crystals, and biphenyl-based liquid crystals.

The asymmetry of the pretilt angle can be represented by the difference (Δθ) in the absolute value of the pretilt angle between the upper and lower substrates. Also, as described above, since the pretilt angles θ0 and θnp-1 are defined to have different signs, the difference (Δθ) in absolute value of the pretilt angles can be represented by Δθ=|θ0+θnp-1|.

(a) of FIG. 46 shows the result of calculating the relationship between the absolute value difference (Δθ) of the pretilt angle between the upper and lower substrates and the critical electric field Ec. a in Fig. 46 is the calculation result when k11=6×10 ^-7 dyn, k33=12×10 ^-7 dyn, and Δε=10. As shown in a of FIG. 6 , the greater the difference in the pretilt angles, the more the critical electric field Ec decreases. Especially in the range above Δθ≥0.0002rad, Ec will drop sharply as Δθ increases.

Therefore, in order to realize rapid liquid crystal transition, it is effective to make the difference of the pretilt angle more than 0.0002 rad, ideally more than 0.035 rad. In addition, the upper limit of the difference Δθ of the pretilt angles is not particularly limited, but it is usually set to be less than 1.58 rad, preferably less than 0.785 rad.

In addition, the absolute values of the pretilt angles θ0 and θnp-1 should normally exceed 0 rad and be less than 1.57 rad, and are ideally adjusted so as to be greater than 0.017 rad and less than 0.785 rad. The adjustment of the pretilt angle can be controlled by forming an appropriate liquid crystal alignment film on the surface of the substrate by oblique vapor deposition and Langmuir-Blodgett (LB) method. . Although it does not specifically limit as a liquid crystal aligning film, For example, polyimide resin, polyvinyl alcohol, polystyrene resin, polysiname-to resin, calcon system resin, polypeptide resin, polymer liquid crystal, etc. are mentioned. In addition, in addition to the material selection of the liquid crystal alignment film, in the case of the oblique evaporation method, the method of adjusting the inclination of the evaporation direction to the substrate surface is adopted, and in the case of the LB method, the method of adjusting the inclination of the substrate surface is adopted. By adjusting the pull-up speed and other conditions, the pretilt angle can be controlled.

In addition, the critical electric field Ec will also be affected by the inhomogeneity of the electric field in the liquid crystal layer. This is because the distortion of the electric field generated in the liquid crystal layer affects the stability of the alignment state of the liquid crystal molecules. In addition, the non-uniformity of the electric field can be represented by the ratio (E1/E0) of the main electric field E0 applied substantially uniformly to the liquid crystal layer and the sub-electric field E1 applied non-uniformly to the liquid crystal layer. In addition, E1 is the maximum value of the sub electric field that can be applied.

The relationship between the non-uniformity E1/E0 of the electric field and the critical electric field Ec can be studied as follows according to the above-mentioned method. That is, under the condition that the main electric field E0, which is a uniform electric field, is applied to the liquid crystal layer as the external electric field E, and the sub-electric field E1, which is an inhomogeneous electric field, is superimposed on the liquid crystal layer, the calculation occurs with the increase of the main electric field E0. The change of the orientation angle θj. At this time, the sub electric field E1 increases with the increase of the main electric field E0 so that E1/E0 becomes a predetermined value and becomes constant. As the main electric field E0 when the orientation angle θj changes suddenly, the critical electric field Ec of the liquid crystal transition can be calculated according to the obtained calculation results.

FIG. 47 shows an example of the calculation results of calculating the critical electric field Ec under various conditions by varying the value of E1/E0 based on the above method. In addition, the results in Figure 7 are calculated by fixing the boundary conditions as θ0=+0.26rad, θnp-1=-0.125rad, k11=6×10 ^-7 dyn, k33=12×10 ^-7 dyn, Δε=10 the result of. As shown in FIG. 47, the larger E1/E0, that is, the larger the non-uniformity of the electric field, the greater the increase of the critical electric field Ec, and Ec becomes infinitely small near E1/E0=1. This is considered to be because when there is distortion in the electric field of the liquid crystal layer, the uniform alignment becomes unstable compared with a case where the electric field is uniform, and as a result, transition to the bend alignment is rapidly achieved.

Therefore, in order to realize rapid liquid crystal transfer, it is effective to apply the electric field E1 spatially non-uniformly to the liquid crystal layer together with the substantially uniform main electric field E0. In particular, it is effective to set 0.01<E1/E0<1. This is because if it is in the range of E1/E0≤0.01, it is difficult to fully obtain the effect of promoting the liquid crystal transfer caused by the application of a uniform electric field. If it is in the range of E1/E0≥0.01, due to the applied voltage Since the size becomes too large, there is a problem that it is not suitable for actual use. In addition, it is desirable to set 0.5≦E1/E0≦1.

The uneven electric field E1 can be applied in the direction perpendicular to the substrate for the liquid crystal layer by using the voltage applied between the source electrode and the transparent electrode of the thin film transistor. In addition, the non-uniform electric field E1 is preferably an AC electric field with a frequency of 100 Hz or less, and it is also desirable to attenuate the amplitude over time.

Within the three conditions of the ejection elastic coefficient (k11), the asymmetry of the pretilt angle (Δθ) and the non-uniformity of the electric field (E1/E0), which are the conditions for reducing the critical electric field Ec, it is desirable to make the Make combinations that meet two conditions or three conditions. Because these conditions are combined, the critical electric field Ec can be lowered more reliably than when only one of the conditions is satisfied.

For example, b in FIG. 46 is the result of calculation under the same conditions as in a in FIG. 46 , except that a non-uniform electric field E1 is added together with a substantially uniform external electric field E0. In addition, b in FIG. 46 is the result when E1/E0=0.03. From the comparison of a and b in Figure 46, it can be seen that the critical electric field Ec can be further reduced by combining the two conditions of the asymmetry of the pretilt angle and the inhomogeneity of the electric field, and rapid liquid crystal transfer can be realized. .

Possibility of industrial use

As described above, according to the present invention, the various objects of the present invention can be fully achieved.

As described above, if the present invention is adopted, the method of applying the AC voltage superimposed with the bias voltage to a pair of substrates by using the driving method of the liquid crystal display device using the OCB unit, and continuously applying the AC voltage, or using Alternately repeating the process of applying an AC voltage with a bias voltage superimposed on a pair of substrates and the process of adding a low voltage to the OPEN state or applying a low voltage can basically complete the process from spray alignment to the substrate in a very short time. By shifting to bend alignment, a bend alignment type OCB liquid crystal display device with no display defects, fast response speed, suitable for animation display, and wide field of view can be obtained.

In addition, if the present invention is adopted, the following effects can be obtained: it is possible to obtain a high-speed response wide range that is composed of an active matrix type liquid crystal cell that can reliably and quickly perform transition from spray alignment to bend alignment, and has no display defects. A liquid crystal display device in an OCB display mode with a wide field of view and high image quality.

In addition, if the present invention is adopted, in the spray-aligned liquid crystal cell in which the positive and negative pretilt angles of the liquid crystals at the upper and lower interfaces of the liquid crystal layer between the array substrate and the opposite substrate are opposite to each other, and have been aligned parallel to each other, When the voltage is not applied, it has become a spray alignment. Before the liquid crystal display is driven, an initialization process is performed to transfer the alignment state of the above-mentioned liquid crystal layer from a spray alignment to a bend alignment by applying a voltage. In a display-driven active matrix liquid crystal display device, in a pixel, there is at least one transverse electric field applying part for transfer excitation, and while the transverse electric field is generated by the transverse electric field applying part, the pixel electrode and the common Continuously or intermittently apply a voltage between the electrodes, so that each pixel has a transfer nucleus, so that the entire pixel is transferred from the spray orientation to the bend orientation, and the transfer from the spray orientation to the bend orientation is quickly and surely produced. Therefore, it is possible to provide an OCB mode liquid crystal display device with no display defect, high-speed response, wide-field-of-view and high-quality image

In addition, if the present invention is adopted, the alignment liquid crystal display device of the OCB display mode is a parallel alignment liquid crystal display device provided with a liquid crystal layer sandwiched between a pair of substrates and a phase compensating plate disposed outside the substrates, and a reliable And the high-speed spray-bend orientation transfer has great practical value.

In addition, according to the present invention, in the method of transferring the orientation of the liquid crystal to the bend orientation by applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, the ejection elasticity of the liquid crystal The coefficient k11 is in the range of 10×10 ^-7 dyn ≥ k11 ≥ 6×10 ^-7 dyn, and assuming that the absolute value of the pretilt angle of the liquid crystal relative to the first substrate is θ1, the pretilt angle of the liquid crystal relative to the second substrate is When the absolute value of the inclination angle is θ2, the relationship of 1.57rad>|θ1-θ2|≥0.0002rad is satisfied, so the liquid crystal can be quickly transferred to the bend orientation.

In addition, according to the present invention, since an electric field is applied to the liquid crystal held between the first substrate and the second substrate facing each other, in the method of transferring the orientation of the liquid crystal to the bend orientation, when the ejection modulus of the liquid crystal is set to k11 is in the range of 10×10 ^-7 dyn ≥ k11 ≥ 6×10 ^-7 dyn, and the above-mentioned electric field is superimposed on the main electric field applied uniformly in space by the secondary electric field applied spatially unevenly The electric field satisfies the relationship of 1.0>E1/E0>1/100 when the above-mentioned main electric field is E0 and the above-mentioned sub-electric field is E1, so that the liquid crystal can be rapidly shifted to a bend orientation.

In addition, according to the present invention, in the method of transferring the orientation of the liquid crystal to the bend orientation by applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, when the liquid crystal is set to the above-mentioned first substrate, 1. When the absolute value of the pretilt angle of the substrate is θ1 and the absolute value of the pretilt angle of the liquid crystal relative to the second substrate is θ2, the relationship of 1.57rad>|θ1-θ2|≥0.0002rad is satisfied, and the above-mentioned electric field It is the electric field that superimposes the auxiliary electric field applied unevenly in space on the main electric field applied uniformly in space. When the above-mentioned main electric field is E0 and the above-mentioned auxiliary electric field is E1, it satisfies 1.0>E1/E0>1 /100 relationship, so the liquid crystal can be quickly transferred to the bend orientation.

In addition, according to the present invention, in the method of transferring the orientation of the liquid crystal to the bend orientation by applying an electric field to the liquid crystal held between the first substrate and the second substrate facing each other, the ejection elasticity of the liquid crystal The coefficient k11 is in the range of 10×10 ^-7 dyn≥k11≥6×10 ^-7 dyn, the absolute value of the pretilt angle of the liquid crystal relative to the first substrate is θ1, and the pretilt angle of the liquid crystal relative to the second substrate is When the absolute value of θ2 is θ2, the relationship of 1.57rad>|θ1-θ2|≥0.0002rad is satisfied, and the above electric field is assumed to be the main electric field applied uniformly in space by superimposing the auxiliary electric field applied unevenly in space The electric field above satisfies the relationship of 1.0>E1/E0>1/100 when the above-mentioned main electric field is E0 and the above-mentioned sub-electric field is E1, so the liquid crystal can be rapidly transferred to a bend orientation.

The above-mentioned specific embodiments are fundamentally intended to make the technical content of the present invention clearer, and should not be construed narrowly as being limited to these specific examples. Within the spirit of the present invention and the scope of the claims described below, further Various changes may be made and implemented.

Claims (10)

1. liquid crystal indicator, it is the liquid crystal indicator of active matric, possess liquid crystal layer that is clamped between a pair of substrate and the phase compensator that is provided in the outside of substrate, the pre-tilt angle of the liquid crystal of above-mentioned liquid crystal layer upper and lower interface is positive and negative reciprocal when making alive not, and be to have carried out the injection orientation of orientation process in parallel with each other, before liquid crystal display drives, by means of adding voltage, make the state of orientation of above-mentioned liquid crystal layer carry out transferring to the initialization process of curved orientation from spraying orientation, carrying out under this initialized curved orientation state, carrying out liquid crystal display drives

It is characterized in that: the thickness that at least one place has a liquid crystal layer in display element than around little zone, and it is big to be added in the electric field intensity that electric field ratio on the liquid crystal layer in the above-mentioned zone adds on around the liquid crystal layer.

2, a kind of liquid crystal indicator, it is the liquid crystal indicator of active matric, possess liquid crystal layer that is clamped between a pair of substrate and the phase compensator that is provided in the outside of substrate, the pre-tilt angle of the liquid crystal of above-mentioned liquid crystal layer upper and lower interface is positive and negative reciprocal when making alive not, and be to have carried out the injection orientation of orientation process in parallel with each other, before liquid crystal display drives, apply the state of orientation of carrying out above-mentioned liquid liquid crystal layer by means of voltage and transfer to the initialization process of curved orientation from spraying orientation, carrying out under this initialized curved orientation state, carrying out liquid crystal display drives

It is characterized in that: the thickness that at least one place has a liquid crystal layer outside display element than around little zone, and it is big to be added in the electric field intensity that electric field ratio on the liquid crystal layer in the above-mentioned zone adds on around the liquid crystal layer.

3, a kind of liquid crystal indicator, it is the liquid crystal indicator of active matric, possess liquid crystal layer that is clamped between a pair of substrate and the phase compensator that is provided in the outside of substrate, the pre-tilt angle of the liquid crystal of above-mentioned liquid crystal layer upper and lower interface is positive and negative reciprocal when making alive not, and be to have carried out the injection orientation of orientation process in parallel with each other, before liquid crystal display drives, apply the state of orientation that makes above-mentioned liquid crystal layer by means of voltage and transfer to the initialization process of curved orientation from spraying orientation, carrying out under this initialized curved orientation state, carrying out liquid crystal display drives

It is characterized in that: at least one place has the concentrated position of electric field in display element.

4. the described liquid crystal display device of claim 3 is characterized in that: the above-mentioned electric field that is arranged in the display element is concentrated the position, be to the thickness direction top of liquid crystal layer the show electrode that highlights or a part or their two sides of common electrode.

5. liquid crystal indicator, it is the liquid crystal indicator of active matric, possess liquid crystal layer that is clamped between a pair of substrate and the phase compensator that is provided in the outside of substrate, the pre-tilt angle of the liquid crystal of above-mentioned liquid crystal layer upper and lower interface is positive and negative reciprocal when making alive not, and be to have carried out the injection orientation of orientation process in parallel with each other, before liquid crystal display drives, apply the state of orientation that makes above-mentioned liquid crystal layer by means of voltage and transfer to the initialization process of curved orientation from spraying orientation, carrying out under this initialized curved orientation state, carrying out liquid crystal display drives

It is characterized in that: at least one place has the concentrated position of electric field outside display element.

6. the described liquid crystal indicator of claim 5 is characterized in that: it is the part of the electrode that partly highlights on the thickness direction of liquid crystal layer that above-mentioned electric field is concentrated the position.

7. liquid crystal indicator, it is the liquid crystal indicator of active matric, possess liquid crystal layer that is clamped between a pair of substrate and the phase compensator that is provided in the outside of substrate, the pre-tilt angle of the liquid crystal of above-mentioned liquid crystal layer upper and lower interface is positive and negative reciprocal when making alive not, and be to have carried out the injection orientation of orientation process in parallel with each other, before liquid crystal display drives, apply the state of orientation that makes above-mentioned liquid crystal layer by means of voltage and transfer to the initialization process of curved orientation from spraying orientation, carrying out under this initialized curved orientation state, carrying out liquid crystal display drives

It is characterized in that: on the part of show electrode or common electrode or their two sides, have opening portion.

8. the described liquid crystal indicator of claim 7 is characterized in that: above-mentioned opening portion is to have the pixel capacitors that forms on planarization film of active matrix type LCD device of opening device and the conducting orifice that is electrically connected with this switching device.

9. the described liquid crystal indicator of claim 1 is characterized in that: above-mentioned phase compensator possesses the phase compensator that a negative anisotropic optical media of refractive index that is mixed to arrange by main shaft constitutes at least.

10. the described liquid crystal indicator of claim 9, it is characterized in that: above-mentioned phase compensator possesses a positive phase compensator at least.

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