CN101135796A - Liquid crystal display device and electronic equipment - Google Patents

Abstract

The present invention provides a vertical alignment mode liquid crystal display device with high image quality and wide viewing angle. The liquid crystal display device (100) of the present invention is: a pair of substrates (10, 25) arranged opposite to each other sandwich a liquid crystal layer (50) that is vertically aligned in an initial state, and in a dot region constituting one display unit, A plurality of alignment control structures including dielectric protrusions (18) protruding from the inner surface of the substrate (10) to the liquid crystal layer (50) are provided, and the dielectric coefficient of the dielectric protrusions (18) is set to ε _t1 to form When the long-axis direction permittivity of the liquid crystal molecules of the above-mentioned liquid crystal layer (50) is ε _∥ and the short-axis direction permittivity is ε _⊥ , the above-mentioned permittivity ε _t1 > ε _∥ > ε _⊥ has ε _⊥ > ε _∥ > According to the relationship of ε _t1 , an edge portion (31a) as the alignment control structure adjacent to the dielectric protrusion (18) is provided on the substrate (25) opposite to the substrate provided with the dielectric protrusion (18).

Description

Liquid crystal display device and electronic equipment

technical field

The present invention relates to a liquid crystal display device and electronic equipment.

Background technique

In recent years, liquid crystal display devices having a liquid crystal mode of homeotropic alignment have been put into practical use. In such a liquid crystal display device, it is necessary to accurately control the inclination direction of the liquid crystal vertically aligned to the substrate when a voltage is applied, and it has been realized to provide a slit (cutout portion) on the electrode for the purpose of this orientation control. Or the technique of an orientation control structure composed of dielectric protrusions (see Patent Document 1). In addition, studies have been conducted on the arrangement conditions of the above-mentioned dielectric protrusions (see Non-Patent Document 1).

[Patent Document 1] Patent No. 2947350

[Non-Patent Document 1] A Super-High Image QuaLityMuLti-Domain Vertical Alignment LCD by New Rubbing-Less Technology, SID 1998 DIGEST41.1.

As shown in the prior art described above, providing an alignment control structure and then setting its arrangement conditions correctly is effective in improving the image quality of a vertical alignment mode liquid crystal display device. However, as the inventors of the present invention have repeatedly studied for the purpose of further improving the image quality and widening the viewing angle of the liquid crystal display device in the vertical alignment mode, it has been found that when the dielectric protrusion is provided as the above-mentioned alignment control structure, it must be based on The properties of liquid crystals provide dielectric protrusions with suitable properties. In other words, in the conventional liquid crystal display device in which the orientation control of the vertically aligned liquid crystal is performed by means of dielectric protrusions when the above-mentioned optimization is not performed, there is a possibility that the image quality may degrade on the contrary.

Contents of the invention

The present invention provides means for solving this problem, and an object of the present invention is to provide a vertical alignment mode liquid crystal display device that achieves high image quality and wide viewing angle.

In order to solve the above-mentioned problems, the present invention is a liquid crystal display device in which a liquid crystal layer having a vertical alignment in an initial state is sandwiched between a pair of substrates having electrodes on opposite surfaces, wherein the dots constituting one display unit are In the area, on one substrate of the pair of substrates, a dielectric protrusion protruding toward the liquid crystal layer side is formed on the electrode, and on the opposite side of the other substrate of the pair of substrates, the The dielectric protrusions are provided with alignment control structures at positions adjacent to each other in the planar direction. Assuming that the dielectric coefficient of the above-mentioned dielectric protrusions is ε _t1 , the dielectric coefficient of the long-axis direction of the liquid crystal molecules constituting the above-mentioned liquid crystal layer is ε _∥ , short When the permittivity in the axial direction is ε _⊥ , there is a relationship of ε _⊥ >ε _∥ >ε _t1 . If this structure is adopted, in a liquid crystal display device having dielectric protrusions as an alignment control structure for vertically aligned liquid crystals, when the dielectric coefficient of the dielectric protrusions is smaller than that of the long-axis direction of the liquid crystal molecules, it is possible to By controlling the orientation of the liquid crystal in the dot area well, a display with a wide viewing angle and high luminance can be obtained.

In addition, the present invention is a liquid crystal display device in which a liquid crystal layer having a vertical alignment in an initial state is sandwiched between a pair of substrates having electrodes on opposite surfaces, and is characterized in that in a dot region constituting one display unit, One substrate of the pair of substrates is provided with a dielectric protrusion formed to protrude from the above-mentioned electrodes of the substrate toward the liquid crystal layer, and an alignment control structure disposed adjacent to the dielectric protrusion, and the dielectric protrusion is provided. The permittivity of ε t1 is ε _t1 , and when the permittivity of the liquid crystal molecules constituting the liquid crystal layer is ε _∥ in the major axis direction and ε _⊥ in the minor axis direction, there is a relationship of ε _t1 >ε _∥ . If this structure is adopted, in a liquid crystal display device provided with dielectric protrusions as an alignment control structure for vertically aligned liquid crystals, when the dielectric coefficient of the dielectric protrusions is greater than that of the long-axis direction of the liquid crystal molecules, it is possible to By controlling the orientation of the liquid crystal in the dot area well, a display with a wide viewing angle and high luminance can be obtained. Furthermore, in this configuration, since the orientation control structure can be provided on only one of the substrates, the easiness of manufacture is enhanced, and an improvement in manufacturing yield can be expected.

Therefore, if each of the above-mentioned configurations is adopted, in a liquid crystal display device having a dielectric protrusion as an alignment control structure for vertically aligned liquid crystals, it is possible to accurately control the voltage application of liquid crystal molecules having different permittivity due to the dielectric protrusion. Therefore, it is possible to provide a liquid crystal display device capable of obtaining a high-intensity display.

In the liquid crystal display device of the present invention, the alignment control structure adjacent to the dielectric protrusion may be an opening slit formed on the electrode provided in the dot region or an edge portion of the electrode.

In addition, in the liquid crystal display device of the present invention, it is also possible to have a structure in which the alignment control structure adjacent to the above-mentioned dielectric protrusion is another dielectric protrusion, and the dielectric coefficient of the other dielectric protrusion is ε _t2 When , the permittivity ε _∥ of the above-mentioned liquid crystal molecules has a relationship of ε _∥ >ε _t2 .

In the liquid crystal display device of the present invention having the conventional structure, as the alignment control structure adjacent to the dielectric protrusion, the alignment control of the liquid crystal molecules at the time of voltage application by the oblique electric field generated on the edge of the electrode can be applied. structure, and any structure in which the orientation is controlled by distorting the electric field by providing protrusions with different permittivity in the liquid crystal layer.

In the liquid crystal display device of the present invention, it is desirable that the orientation control structure adjacent to the above-mentioned dielectric protrusion has an opening slit formed on the electrode provided in the above-mentioned dot region, and a dielectric material provided inside the opening slit. The coefficient ε _t2 has an additional dielectric protrusion of the relationship ε _∥ >ε _t2 . If this configuration is adopted, since an orientation control structure is provided to control the orientation of liquid crystal molecules by means of an oblique electric field generated around the opening gap and electric field distortion caused by dielectric protrusions, the distance from the orientation control structure is Orientation control of the liquid crystal molecules at a certain position can be well performed, forming a structure that is advantageous in terms of response speed and improvement of aperture ratio.

In addition, the present invention provides a liquid crystal display device, which is a liquid crystal display device in which a liquid crystal layer with a vertical orientation in an initial state is sandwiched between a pair of substrates having electrodes on opposite surfaces, and is characterized in that: In the dot area of each display unit, on one of the pair of substrates, a first dielectric protrusion protruding toward the liquid crystal layer side is formed on the electrode, and on the other substrate of the pair of substrates, A second dielectric protrusion is formed on the electrode at a position adjacent to the first dielectric protrusion in the planar direction. Let the permittivity of the above-mentioned first dielectric protrusion be ε _t1 , the permittivity of the above-mentioned second dielectric protrusion be ε _t2 , set the permittivity of the long-axis direction of the liquid crystal molecules constituting the above-mentioned liquid crystal layer to be ε _∥ , and the short-axis When the permittivity of the direction is ε _⊥ , it has the relationship of ε _t1 >ε _∥ and ε _t2 >ε _∥ . Normally, the dielectric protrusions provided on the dot regions and constituting the orientation control structure can naturally be formed of the same material, but orientation control may be performed by dielectric protrusions having different permittivity. Therefore, when the dielectric protrusions having such different permittivity are adjacently provided, it is desirable to respectively provide the dielectric protrusions on different substrates as in this configuration. By adopting such a structure, a display with high image quality and wide viewing angle can be obtained.

In the liquid crystal display device of the present invention, a reflective display region for reflective display and a transmissive display region for transmissive display may be provided in the dot region. According to this configuration, a transflective liquid crystal display device capable of high-quality transmissive/reflective display can be provided.

Next, the present invention also provides electronic equipment characterized by including the aforementioned liquid crystal display device of the present invention. According to the present invention, it is possible to provide an electronic device having a display portion with a wide viewing angle and high luminance.

Description of drawings

FIG. 1 is a cross-sectional configuration diagram showing the basic configuration of the liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional configuration diagram showing the basic configuration of the liquid crystal display device of the present invention.

Fig. 3 shows the simulation results of the embodiment.

Fig. 4 shows the simulation results of the embodiment.

Fig. 5 shows the simulation results of the embodiment.

Fig. 6 shows the simulation results of the embodiment.

Fig. 7 shows the simulation results of the embodiment.

Fig. 8 shows the simulation results of the embodiment.

Fig. 9 shows the simulation results of the embodiment.

Fig. 10 shows the simulation results of the embodiment.

FIG. 11 is an explanatory diagram showing an example of a liquid crystal display device to which the present invention can be applied.

FIG. 12 is a three-dimensional structure of a liquid crystal display device as a configuration example.

FIG. 13 is a cross-sectional configuration diagram of a liquid crystal display device according to a first configuration example.

FIG. 14 is a plan view showing the configuration of one pixel region of the liquid crystal display device of the above configuration example.

FIG. 15 is a cross-sectional configuration diagram of a liquid crystal display device according to a second configuration example.

FIG. 16 is a plan view showing the configuration of one pixel region of the liquid crystal display device of the above configuration example.

The oblique configuration diagram of FIG. 17 shows an example of an electronic device.

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing to be referred to below, the size and thickness of each part are suitably different for the convenience of drawing. Fig. 1 and Fig. 2 are cross-sectional configuration diagrams showing main parts (parts of the basic configuration) of liquid crystal display devices according to Embodiment 1 and Embodiment 2 of the present invention, respectively.

The liquid crystal display device 100 according to Embodiment 1 shown in FIG. 1 has a structure in which a liquid crystal layer 50 made of liquid crystal having a negative dielectric anisotropy is sandwiched between the first substrate 25 and the second substrate 10 arranged to face each other. . On the inner side (the liquid crystal layer side) of the second substrate 10, the second electrode 9, the dielectric protrusion 18, and the vertical alignment film 23 covering the second electrode 9 and the dielectric protrusion 18 are formed in this order. On the inner side of the first substrate 25, the first electrode 31 and the vertical alignment film 33 are formed in this order. In the dot area constituting one display unit, the first electrode 31 is formed to be narrower than the second electrode 9, and above the second electrode 9, a horizontal direction (Y direction/direction of the first substrate 25) is arranged in a planar manner. The edge portion (edge portion/notch portion) 31a, 31a of the first electrode 31 in the planar direction). That is to say, in one dot area, the positional relationship between the edge portion 31a and the edge portion 31a of the first electrode 31 formed on a different substrate is formed by disposing the dielectric protrusion 18 (the dielectric protrusion 18 and the first electrode 31). The edge portions 31a, 31a of 31 are arranged in such a relationship that the planes do not overlap and are adjacent to each other differently).

On the other hand, the liquid crystal display device 200 of the second embodiment shown in FIG. 2 has the same basic configuration as that of the liquid crystal display device of the first embodiment. The difference is that the dielectric protrusion 18 is provided on the first electrode 31 of the first substrate 25 . That is to say, the positional relationship in which the dielectric protrusions 18 are arranged between the edge portions 31a and the edge portions 31a of the first electrode 31 formed on the same substrate in one dot area (the dielectric protrusions 18 and the dielectric protrusions 18 are arranged adjacently and alternately The positional relationship of the edge portions 31a, 31a of the first electrode 31).

In addition, the so-called dot area is an area that constitutes one display unit, for example, generally speaking, it is composed of a pixel electrode formed on one substrate and a counter electrode formed on the other substrate facing it. .

Based on such a configuration, in these liquid crystal display devices 100 and 200, the liquid crystal molecules 51 constituting the liquid crystal layer 50 are in a state (non-selected state, initial alignment state) in which no voltage has been applied to the two electrodes 9 and 31. , the following actions: by the alignment restriction force of the vertical alignment film 23,33 in the vertical direction with respect to the substrate 10,25, when a voltage is applied between the two electrodes (becoming into a selected state), it is directed toward the substrate 10,25 face direction.

In addition, in the liquid crystal display devices 100 and 200, the dielectric protrusion 18, which is an alignment control structure for controlling the alignment direction of the liquid crystal molecules 51 when the above-mentioned voltage is applied, is also formed so that Orientation of the liquid crystal molecules 51 can also be controlled by the distortion of the electric field generated in the edge portion (edge portion/notch portion) 31a of the electrode provided on the substrate facing the narrower electrode. In addition, in the liquid crystal display devices of these first and second embodiments, the dielectric constant (ε _t1 ) of the dielectric protrusion 18 and the dielectric constant (ε t1 ) of the liquid crystal molecules 51 provided in substantially the center of one dot area are _∥ , ε _⊥ ) are different from each other in the relationship, and due to the difference in the relationship, the arrangement relationship between the dielectric protrusion 18 and the adjacent orientation control structure (edge portions 31 a , 31 a ) is also different. Here, the permittivity ε _∥ of the liquid crystal molecules is the permittivity of the long axis direction of the liquid crystal molecules (the X direction shown in the figure), and the permittivity ε _⊥ is the permittivity of the short axis direction of the liquid crystal molecules (the Y direction shown in the figure). dielectric coefficient. Hereinafter, ε _∥ and ε _⊥ are called the permittivity in the major axis direction and the permittivity in the minor axis direction, respectively.

First, in the liquid crystal display device 100 of Embodiment 1 shown in FIG. 1 , the dielectric constant ε _t1 of the dielectric protrusion 18 that is used to form the liquid crystal alignment control means is set to be greater than the dielectric constant of the long-axis direction of the liquid crystal molecules 51. ε _∥ is small, that is, the dielectric coefficient ε _t1 of the dielectric protrusion 18 and the dielectric coefficients ε _∥ and ε _⊥ of the liquid crystal molecules 51 have a relationship of ε _⊥ >ε _∥ >ε _t1 . On the other hand _, in the liquid crystal display device 200 of Embodiment 2 shown in _FIG . _t1 >ε _∥ ).

In addition, the above-mentioned two liquid crystal display devices also differ in the arrangement of the dielectric protrusions 18 . As described above, in the liquid crystal display device of the present invention, the orientation control structure of the dielectric protrusion 18 and the adjacent dielectric protrusion 18 is appropriately arranged according to the relationship between the dielectric coefficient of the dielectric protrusion 18 and the dielectric coefficient of the liquid crystal molecules 51. The liquid crystal display device can obtain a good display with high image quality and wide viewing angle by means of a liquid crystal display device in which the disposition relationship between objects (the edge portion 31a of the electrode) is adjusted.

3 to 10, the behavior of liquid crystal molecules corresponding to the relationship between the dielectric coefficient ε _t1 of the dielectric protrusion 18 and the dielectric coefficient ε _∥ , ε _⊥ of the liquid crystal molecules 51 and the liquid crystal display of this embodiment The function of the device is described. 3 to 10 are cross-sectional configuration diagrams showing simulation results for calculating the behavior of liquid crystal molecules when the dielectric coefficients of the dielectric protrusions 18 are different.

In Fig. 3 and Fig. 4, it is shown that the permittivity ε _t1 of the dielectric protrusion is 1.0, the permittivity ε _∥ of the long axis direction of the liquid crystal molecules is 4.0, and the permittivity ε _⊥ of the short axis direction is 9.0 In the liquid crystal display device of the main part (regarded as a part of the basic configuration) in the one-dot area of 9.0, the state of the liquid crystal immediately after a voltage is applied between the two electrodes 9 and 31 (FIG. 3) and the The state of the liquid crystal after 100ms (Figure 4).

In addition, in the simulations that show the results in FIGS. In the upper central portion, the first electrode 31 is formed narrower than the second electrode 9 , and the edge portions 31 a, 31 a of the first electrode 31 are arranged above the second electrode 9 .

In Fig. 5 and Fig. 6, it is shown that the permittivity ε _t1 of the dielectric protrusion is 3.5, the permittivity ε _∥ of the long axis direction of the liquid crystal molecules is 4.0, and the permittivity ε _⊥ of the short axis direction is 9.0 In the liquid crystal display device of the main part (regarded as a part of the basic configuration) in the one-dot area of 9.0, the state of the liquid crystal immediately after a voltage is applied between the two electrodes 9 and 31 (FIG. 5) and the The state of the liquid crystal after 100ms (Figure 6).

In Fig. 7 and Fig. 8, it is shown that the permittivity ε _t1 of the dielectric protrusion is 5.0, the permittivity ε _∥ of the long axis direction of the liquid crystal molecules is 4.0, and the permittivity ε _⊥ of the short axis direction is 9.0 In the liquid crystal display device of the main part (regarded as a part of the basic configuration) in the one-dot area of 9.0, the state of the liquid crystal immediately after a voltage is applied between the two electrodes 9 and 31 (FIG. 7) and the The state of the liquid crystal after 100ms (Figure 8).

As shown in these figures, under the conditions of FIGS. 3 to 6 in which the dielectric protrusion 18 and the liquid crystal molecule 51 have a relationship of ε _t1 <ε _∥ , the liquid crystal molecule 51 falls from the dielectric protrusion 18 toward both sides (electrode edge direction), Two liquid crystal domains bordered by the dielectric protrusion 18 are symmetrically formed. Next, the orientation control function of the edge portion 31a and the dielectric protrusion 18 will be described.

In the absence of means to control the orientation of the liquid crystal molecules, the liquid crystal molecules are randomly toppled due to voltage application, and in this case, discontinuous lines ( disclination) to cause an afterimage or a decrease in luminance. In addition, since the disclination appears at different positions due to the applied voltage, the size of the liquid crystal domains in the dot area becomes unstable, and furthermore, since the liquid crystal domains respectively have different viewing angle characteristics, the result becomes When viewed obliquely, it appears as rough, dirt-like unevenness. Therefore, by providing means for controlling the orientation of liquid crystal molecules, it is possible to tilt and align the liquid crystal molecules in a predetermined direction when a voltage is applied.

First, the function of the dielectric protrusion 18 will be described with reference to FIGS. 3 and 4 . Since the alignment film 23 has been formed on the surface of the second electrode 9 containing the dielectric protrusion 18, as shown in FIG. The substrate surface is vertical. Here, when a voltage is applied to the first electrode 31 and the second electrode 9, an electric field represented by an equipotential line 52 will be formed on the liquid crystal layer 50, especially around the dielectric protrusion 18, due to The difference in permittivity between the dielectric protrusions 18 and the liquid crystal molecules 51 generates distortion of the electric field. In addition, when such distortion occurs, as a result, liquid crystal molecules 51 aligned vertically to the substrate surface have a pretilt angle of a predetermined angle with respect to the electric field. Therefore, the alignment of the liquid crystal molecules 51 can be restricted to tilt outward in the left-right direction of the dielectric protrusion 18 (the direction that increases the contact angle with the inclined surface of the dielectric protrusion 18 ) by voltage application. In addition, the liquid crystal molecules in the peripheral region of the dielectric protrusion 18 also fall in the same direction in the same direction as dominoes fall.

Next, the function of the edge portion 31a of the electrode will be described. Since the alignment film 33 covering the edge portion 31a is also formed, the liquid crystal molecules 51 are aligned perpendicular to the substrate surface when no voltage is applied. Here, when a voltage is applied to the first electrode 31 and the second electrode 9, as indicated by the equipotential line 52, an oblique electric field is generated around the electrode edge portion 31a. As a result, when viewed from this oblique electric field, the long axis direction of the liquid crystal molecules 51 when no voltage is applied is aligned at a predetermined angle, which is equivalent to giving the liquid crystal molecules a pretilt angle. Therefore, it is possible to restrict the orientation of the liquid crystal molecules 51 to fall from the edge portion 31a to the electrode central portion side by voltage application. In addition, those liquid crystal molecules 51 arranged on the inner side of the edge portion 31a (the electrode central portion side) can also be arranged one by one in the same direction along the alignment direction of the liquid crystal molecules on the edge portion 31a in a domino-toppling manner. dump.

By means of the above effects, the liquid crystal molecules 51, which are restricted by the orientation of the dielectric protrusion 18 and the edge portion 31a of the electrode, will fall in the same direction between the dielectric protrusion 18 and one edge portion 31a. As a result, as shown in FIG. As shown in FIGS. 4 and 6 , substantially symmetrical liquid crystal domains centered on the dielectric protrusion 18 can be formed. Therefore, the liquid crystal display device 100 of the embodiment shown in FIG. 1 configured under the same conditions as those shown in FIGS. 3 to 6 can obtain a display with a wide viewing angle and high luminance.

In contrast, under the conditions shown in FIGS. 7 and 8 , the dielectric protrusions 18 and liquid crystal molecules 51 have a relationship of ε _t1 >ε _∥ in terms of their dielectric coefficients. As shown in FIG. 8 , the liquid crystal molecules 51 have a voltage During application, the direction along the inclined surface of the dielectric protrusion 18 (towards the direction of the top of the dielectric protrusion 18, the direction in which the contact angle with the inclined surface of the dielectric protrusion 18 is reduced) is poured, and the liquid crystal molecules in the periphery of the dielectric protrusion 18 51, also tilted towards the side of the dielectric protrusion 18. On the other hand, at the edge portion 31 a of the first electrode 31 , the liquid crystal molecules 51 partially fall toward the center of the first electrode 31 under the same conditions as those shown in FIGS. 3 to 6 . As described above, as a result of the liquid crystal molecules 51 falling in opposite directions between the dielectric protrusion 18 and the edge portion 31a, at an intermediate point between the dielectric protrusion 18 and the edge portion 31a of the first electrode 31, the liquid crystal molecules 51 are If it does not fall, it will go wrong.

As mentioned above, when the value of the permittivity ε _t1 of the dielectric protrusion 18 is different from the permittivity _ε∥ of the liquid crystal molecules 51, the result is that the behavior of the liquid crystal molecules 51 when the voltage is applied is different. Under the condition of ε _t1 <ε _∥ shown in Figure 6, although a high-intensity display can be obtained in a wide viewing angle range, but under the condition of ε _t1 >ε _∥ shown in Figures 7 and 8, the display quality is poor. will decrease due to disclination in the dot region. The difference in the behavior of the liquid crystal molecules between the above conditions is due to the difference in the shape of the distortion of the electric field generated in the liquid crystal layer 50 due to the difference in dielectric coefficient between the dielectric protrusion 18 and the liquid crystal. for the sake. That is, this is because under the conditions of FIG. 4 and FIG. 6 , the shape of the equipotential line 52 shown in the two figures produces the distortion of the electric field projecting to the upper side above the figure of the dielectric protrusion 18. Under the conditions shown in FIG. 8 , on the contrary, distortion of the electric field protruding downward occurs, and as a result, the inclination directions of the liquid crystal molecules 51 are different. This is because the liquid crystal domains generated in the liquid crystal layer 51 also become different liquid crystal domains.

As described above, under the conditions (ε _t1 >ε _∥ ) shown in FIGS. 7 and 8 , it is impossible to obtain a good display. Then, the inventors of the present invention repeatedly studied the structure of the liquid crystal display device to obtain good display even under the conditions shown in FIGS. 7 and 8 , and found that as long as the Dielectric protrusions 18 are provided on the side of the first substrate 25 having another alignment control structure (the edge portion 31a of the first electrode 31), even if a liquid crystal molecule having a relatively high dielectric constant with respect to the dielectric constant _ε∥ of the liquid crystal molecules is used. Even in the case of dielectric protrusions 18, good display can be obtained.

9 and 10 are the results of simulations performed using a liquid crystal display device having the same configuration as the liquid crystal display device 200 shown in FIG. The permittivity ε _t1 of the dielectric protrusion 18 is 5.0, the permittivity ε _∥ of the long axis direction of the liquid crystal molecules 51 is 4.0, and the permittivity ε _⊥ of the short axis direction is 9.0.

As shown in FIG. 10, if the configuration shown in FIG. 2 is adopted, a symmetrical liquid crystal domain centered on the dielectric protrusion 18 can be formed in the liquid crystal layer 50 when a voltage is applied, even under the condition of ε _t1 >ε _∥ , It is also possible to form a liquid crystal display device with a wide viewing angle and a high-brightness display.

In addition, the present inventors also studied the response speed of the liquid crystal display device in the case where the dielectric coefficient ε _t1 of the dielectric protrusion 18 is different. As a result, it was found that in the case of the liquid crystal display device under the condition (ε _t1 =1.0) in FIGS. 3 and 4, compared with the liquid crystal display device under the condition (ε _t1 =3.5) in FIGS. On the other hand, the response speed of about 5ms can be improved. As can be understood by comparing the distributions of the equipotential lines 52 in FIG. 4 and FIG. The orientation restriction force is also large.

In addition, in the above-mentioned embodiment, the case of the edge portion 31a of the first electrode 31 was specifically described as an example of the orientation control structure adjacent to the dielectric protrusion 18, but even The opening slit formed by cutting out a part of the first electrode 31 is provided on both sides of the dielectric protrusion 18 (the part at the end of the dot region of the first electrode 31) instead of the edge of the first electrode 31. The structure of the portion 31a can also obtain the same effect as above.

In addition, in the case of the present invention, even a configuration in which the orientation control structure adjacent to the dielectric protrusion 18 is a separate dielectric protrusion (second dielectric protrusion) is applicable. However, in this case, it is necessary to pay attention to the dielectric constant of the other dielectric protrusion (second dielectric protrusion). That is, as can be seen from the foregoing description, in order to become a dielectric protrusion having an orientation control function equivalent to that of the edge portion 31a of the first electrode 31 or the opening slit, the dielectric constant of the second dielectric protrusion (expressed as ε _t2 ) must have a relationship of ε _t2 <ε _∥ with respect to the permittivity ε _∥ in the long-axis direction of the liquid crystal molecules 51 .

On the other hand, when the permittivity ε _t2 of the second dielectric protrusion has a relationship of ε _t2 >ε _∥ with respect to the permittivity ε _∥ in the long-axis direction of the liquid crystal molecules 1, the liquid crystal molecules 51 are It will pour in from the periphery towards the dielectric protrusion, so in the case of configuring a liquid crystal display device with the second dielectric protrusion, if the structure shown in FIG. 1 is used, the result will be on the same side as the dielectric protrusion 18. (on the electrode 9 of the second substrate), and on both sides between the dielectric protrusions 18, instead of the edge portion 31a of the first electrode 31, the second dielectric protrusions are set. In the structure shown in FIG. 2, On the end portion on the side opposite to the dielectric protrusion 18 (on the electrode 9 of the second substrate), a second dielectric protrusion is provided instead of the edge portion 31a of the first electrode. If these configurations are adopted, even if the second dielectric protrusion having a higher permittivity ε _t2 than the permittivity ε _∥ in the long-axis direction of liquid crystal molecules is provided as an alignment control structure adjacent to the dielectric protrusion 18 In liquid crystal display devices, wide viewing angles and high brightness displays can also be obtained.

(Concrete configuration example of liquid crystal display device)

The configurations described in the above embodiments can be applied to all liquid crystal display devices including vertically aligned liquid crystals having negative dielectric anisotropy. FIG. 11 is a schematic configuration diagram of various liquid crystal display devices. FIG. 11(a) is a transmissive type, (b) is a reflective type, and (c) and (d) are transflective type. In addition, Fig. 11(c) is a case where the first substrate is used as an element substrate and the second substrate is used as a counter substrate, and (d) is a case where the second substrate is used as an element substrate and the first substrate is used as a counter substrate. . In each liquid crystal display device shown in FIG. 11, as long as dielectric protrusions, opening slits, etc. are formed on the surface of the transparent electrode, the above-mentioned effects can be obtained. Therefore, in the embodiments described later, FIG. 11 A transmissive liquid crystal display device shown in (a) will be described as a first configuration example. In addition, as a second configuration example, an example applied to a transflective liquid crystal display device shown in FIG. 11( c ) will be described.

<1st configuration example>

FIG. 12 is a perspective view showing a detailed configuration example of a liquid crystal display device according to a previous embodiment. FIG. 13 is a partial cross-sectional configuration diagram in one dot region of a liquid crystal display device. FIG. 14 is a plan view showing the same liquid crystal display device. The configuration of 1 pixel area composed of 3 dot areas. Although the liquid crystal display devices shown in these figures are active matrix color liquid crystal display devices using TFD (thin film diode) elements (two-terminal nonlinear elements) as switching elements, the present invention can also be used as switching elements. It is used in active matrix liquid crystal display devices using TFT (Thin Film Transistor) elements. In addition, the partial cross-sectional structure shown in FIG. 13 corresponds to the cross-sectional structure along the line A-A shown in FIG. 14 .

As shown in FIG. 12, the liquid crystal display device of this example is mainly composed of an element substrate (first substrate) 25 and an opposing substrate (second substrate) 10 facing each other. Holds the liquid crystal layer not shown. This liquid crystal layer, as conceptually shown in FIG. 13 , is composed of liquid crystals whose initial orientation exhibits a homeotropic orientation and whose dielectric anisotropy is negative. The element substrate 25 is a substrate made of a light-transmitting material such as glass, plastic, or quartz, and is provided with scanning elements on the inner surface side (lower surface side in the figure) in a strip shape with the above-mentioned counter substrate 10 . The lines 9 are made to cross a plurality of data lines 11 extending in a direction. In addition, a plurality of pixel electrodes (first electrodes) 31 made of a transparent conductive material such as ITO (indium tin oxide) and having a substantially rectangular shape in plan view are arranged in a matrix, and at the same time, each pixel electrode is The provided TFD element 13 is connected to the above-mentioned data line 11 .

On the other hand, the counter substrate 10 is also a substrate made of a light-transmitting material such as glass, plastic, or quartz, and a color filter layer 22 and a plurality of layers are formed on the inner surface side (the upper surface side in the drawing). scan lines 9 . The color filter layer 22 is formed by periodically arranging color filters 22R, 22G, and 22B having substantially rectangular shapes in plan view, as shown in FIG. 12 . The respective color filters 22R, 22G, and 22B are formed to correspond to the pixel electrodes 31 of the above-mentioned element substrate 25 . In addition, the scanning lines 9 are formed in a substantially strip shape from a transparent conductive material such as ITO, and extend in a direction intersecting with the data lines 11 of the above-mentioned element substrate 25 . In addition, the scanning line 9 is formed so as to cover the above-mentioned color filters 22R, 22G, and 22B arranged in the extending direction, and functions as a counter electrode (first electrode). In addition, one dot constituted by the formation region of the pixel electrode 31 constitutes one pixel by three dots provided with the color filters 22R, 22G, and 22B.

[section structure]

Next, FIG. 13 is a partial cross-sectional configuration diagram within the region of one dot in FIG. 12 . In FIG. 13 , the TFD element and various wirings on the element substrate 25 are not shown for ease of understanding.

As shown in FIG. 13 , on the liquid crystal layer side of the pixel electrode 31 of the element substrate 25 , a vertical alignment film 33 made of polyimide or the like is formed. In addition, a vertical alignment film 23 made of polyimide is formed on the liquid crystal layer side of the counter electrode 9 in the counter substrate 10 . In addition, both the alignment films 23 and 33 were subjected to a vertical alignment treatment, but no pretilt angle imparting treatment such as rubbing was performed.

In addition, a liquid crystal layer 50 made of a liquid crystal material having a negative dielectric anisotropy is sandwiched between the element substrate 25 and the counter substrate 10 . This liquid crystal material, as conceptually shown by means of liquid crystal molecules 51, is oriented vertically to the alignment film when no voltage is applied, and becomes parallel to the alignment film (that is to say, parallel to the electric field) when a voltage is applied. Orientation vertical). Furthermore, while the element substrate 25 and the counter substrate 10 are bonded to each other by means of a sealing material (not shown) applied to the peripheral portions of the element substrate 25 and the counter substrate 10, the liquid crystal layer 50 is sealed in the into the space formed by the element substrate 25, the counter substrate 10, and the sealing material.

On the other hand, the retardation plate 36 and the polarizing plate 37 are provided on the outer surface of the element substrate 25 , and the retardation plate 26 and the polarizing plate 27 are also provided on the outer surface of the counter substrate 10 . The polarizers 27 and 37 have a function of transmitting only linearly polarized light vibrating in a specific direction. In addition, the retardation plate 26,36 adopts a λ/4 plate having a retardation of substantially 1/4 wavelength for the wavelength of visible light. The phase retardation axis is arranged so that it becomes about 45 degrees, and the circular polarizing plates are constituted by the polarizing plates 27, 37 and the retardation plates 26, 36. By means of the circular polarizer, the linearly polarized light can be converted into circularly polarized light, and the circularly polarized light can be converted into linearly polarized light. In addition, the transmission axis of the polarizing plate 27 and the transmission axis of the polarizing plate 37 are configured to be perpendicular to each other, and the phase lag axis of the retardation plate 26 and the retardation axis of the retardation plate 36 are also configured to be perpendicular to each other. . Further, on the outside of these liquid crystal cells located on the outer side of the counter substrate 10, a backlight (illumination device) 60 having a light source, a reflector, a light guide plate, and the like is provided.

In the liquid crystal display device of the present embodiment shown in FIG. 13, image display can be performed as follows. Light irradiated from the backlight 60 is converted into circularly polarized light after passing through the polarizer 27 and the retardation plate 26 , and enters the liquid crystal layer 50 . In addition, when no voltage is applied, since the liquid crystal molecules aligned perpendicular to the substrate have no refractive index anisotropy, the incident light travels through the liquid crystal layer 50 maintaining the state of circularly polarized light. In addition, the incident light transmitted through the phase difference plate 36 is transformed into linearly polarized light perpendicular to the transmission axis of the polarizer 37 . In addition, since this linearly polarized light does not pass through the polarizing plate 27, in the liquid crystal display device of this embodiment, black display is performed when no voltage is applied (normally black mode).

On the other hand, when a voltage is applied to the liquid crystal layer 50, the liquid crystal molecules will be re-aligned to be parallel to the substrate and have refractive index anisotropy. For this reason, the circularly polarized light incident on the liquid crystal layer 50 from the backlight 60 is converted into elliptically polarized light during transmission through the liquid crystal layer 50 . The incident light is not converted into linearly polarized light perpendicular to the transmission axis of the polarizing plate 37 even after passing through the retardation plate 36 , and all or part of it passes through the polarizing plate 37 . Therefore, in the liquid crystal display device of this embodiment, white display can be performed when a voltage is applied. In addition, gray scale display is also possible by adjusting the voltage applied to the liquid crystal layer 50 .

[Orientation control means]

FIG. 14 is a plan view showing the structure of one pixel area composed of three dot areas of the liquid crystal display device shown in FIG. constitute components. As shown in FIG. 14, on the surfaces of the pixel electrode 31 and the counter electrode 9, opening slits 31b or dielectric protrusions 18 serving as alignment control means for liquid crystal molecules are formed. On the pixel electrode 31 are formed a plurality of opening slits 31 b that are substantially strip-shaped in plan view. In addition, on the surface of the counter electrode 9, a plurality of dielectric protrusions 18 are formed substantially in the shape of a band in plan view. In addition, the arrangement relationship of each dielectric protrusion 18 formed on the counter substrate 10 and each opening slit 31b formed on the element substrate 25 is different from each other alternately with respect to the longitudinal direction of the pixel electrode 31 (planarly non-overlapping). ) to configure. In addition, each protrusion 18 and each slit 31b are arranged such that the interval between each protrusion 18 and the interval between each slit 31b becomes wider as going from one long side of the pixel electrode 31 toward the other long side. In addition, it is also possible to reverse the above, forming an opening slit on the counter electrode 9 and forming a dielectric protrusion on the pixel electrode 31 .

The dielectric protrusion 18 is made of a dielectric material such as resin, and is formed by photolithography using a gray mask or the like. In the case of the liquid crystal display device of this example, in the structure of the liquid crystal display device 100 shown in FIG. The permittivity ε _t1 of the liquid crystal molecule 51 becomes smaller than the permittivity ε _∥ of the liquid crystal molecule 51 in the major axis direction. That is to say, the liquid crystal display device of this configuration example adopts the basic structure and function of the liquid crystal display device shown in FIG. Due to the arrangement relationship between the dielectric protrusion 18 and the opening slit 31b, a good display with a wide viewing angle and high contrast without disclination in the dot area can be obtained.

In addition, in the liquid crystal display device of this configuration example, as a result, the liquid crystal molecules fall radially around the substantially strip-shaped opening slit 31 b when viewed from a planar view. In addition, as a result, the liquid crystal molecules 51 fall radially around the substantially strip-shaped dielectric protrusion 18 as the center. With the help of these dielectric protrusions 18 and opening slits 31b, the liquid crystal molecules are aligned in a certain direction between the dielectric protrusions 18 and the opening slits 31b shown in FIG. Layer 50 performs orientation control.

In addition, in this example, although the alignment control structure adjacent to the dielectric protrusion 18 is formed in a structure in which the opening slit 31b is formed on the electrode provided in the dot region, another structure may be formed inside the opening slit. Dielectric protrusions, dielectric coefficient ε _t2 have a relationship of ε _∥ >ε _t2 and another structure of dielectric protrusions. If this structure is adopted, since the orientation control structure for controlling the orientation of the liquid crystal molecules is provided due to the oblique electric field generated around the opening gap and the electric field distortion generated by the dielectric protrusion, even those separated from the orientation control structure by a distance The liquid crystal molecules can also be well controlled in orientation, and become a structure that is advantageous in terms of improving the response speed and the aperture ratio.

In addition, in this example, although the dielectric protrusion 18 is formed on the counter electrode 9, the counter electrode 9 may be cut out to form a planar slit corresponding to the dielectric protrusion 18, and a dielectric material may be provided inside the slit. Formation of protrusions 18 . That is, at least a part of the counter electrode 9 constituting the base of the dielectric protrusion 18 may be cut out (opening is formed). Such a configuration can increase the distortion of the electric field generated around the dielectric protrusion 18 when a voltage is applied, and can obtain a larger orientation restricting force, so that the response speed of the liquid crystal display device can be improved.

<Configuration example 2>

Next, a second configuration example of the liquid crystal display device of the present invention will be described. 15 is a cross-sectional view in the longitudinal (long side) direction of one dot area of a liquid crystal display device according to this configuration example, and FIG. Plane composition diagram. The liquid crystal display device of this configuration example is a transflective liquid crystal display device. In addition, the detailed description of those parts having the same configuration as that of the first embodiment will be omitted. In addition, the cross-sectional structure shown in FIG. 15 corresponds to the cross-sectional structure along the line B-B in FIG. 16 .

As shown in FIG. 15 , in the liquid crystal display device of the second configuration example, a reflective film 20 made of a metal film having a high reflectance such as aluminum or silver is formed inside a second substrate (counter substrate) 10 . In a part of the reflective film 20, an opening 20a cut out corresponding to the transmissive display area is formed. In addition, the overlapping portion between the formation area of the pixel electrode (first electrode) 31 and the formation area of the reflection film 20 forms a reflection display area, and the formation area of the pixel electrode 31 and the non-formation area of the reflection film 20 (that is, the opening portion 20a) to form a transmissive display area. In addition, a color filter layer 22 is disposed inside the reflective film 20 and the substrate 10 . In addition, in order to compensate for the difference in chromaticity of displayed colors in reflective display and transmissive display, a color material layer for changing color purity may be separately provided in the reflective display area and the transmissive display area.

On the other hand, on the liquid crystal layer side of the element substrate (first substrate) 25 , a pixel electrode 31 , a plurality (three) of dielectric protrusions 18 and a vertical alignment film 33 are provided in this order.

On the upper side of the color filter layer 22, an insulating film 21 is formed at a planar position substantially corresponding to the reflective display area. The insulating film 21 is formed by an organic film such as an acrylic resin, and has a film thickness of about 2 μm±1 μm. The film thickness of the liquid crystal layer 50 in the part where the insulating film 21 is not present is about 2 to 6 microns, and the thickness of the liquid crystal layer 50 on the reflective display area becomes about half of the thickness of the liquid crystal layer 50 on the transmissive display area. That is, the insulating film 21 functions as a liquid crystal layer thickness adjustment layer that makes the layer thickness of the liquid crystal layer 50 differ between the reflective display area and the transmissive display area by its own film thickness, thereby realizing a multi-gap structure. The liquid crystal display device of this example can obtain bright and high-contrast display with this configuration. In addition, near the boundary between the reflective display area and the transmissive display area, an inclined surface that continuously changes the layer thickness of the insulating film 21 is formed.

In the transflective liquid crystal display device shown in FIG. 15, image display can be performed as follows. First, light incident on the reflective display area from above the element substrate 25 is converted into circularly polarized light after passing through the polarizer 37 and the retardation plate 36 , and enters the liquid crystal layer 50 . In addition, when no voltage is applied, since the liquid crystal molecules aligned perpendicular to the substrate have no refractive index anisotropy, the incident light travels through the liquid crystal layer 50 maintaining the state of circularly polarized light. In addition, the incident light reflected by the reflective film 20 and transmitted through the retardation plate 36 is converted into linearly polarized light perpendicular to the transmission axis of the polarizing plate 37 . In addition, this linearly polarized light does not transmit the polarizing plate 37 . On the other hand, the light incident on the transmissive display area from the backlight 60 is also converted into circularly polarized light after passing through the polarizer 27 and the retardation plate 26 , and enters the liquid crystal layer 50 . In addition, the incident light transmitted through the phase difference plate 36 is converted into linearly polarized light perpendicular to the transmission axis of the polarizer 37 . In addition, since this linearly polarized light does not pass through the polarizing plate 37, in the liquid crystal display device of this embodiment, black display is performed when no voltage is applied (normally black mode).

On the other hand, when a voltage is applied to the liquid crystal layer 50, the liquid crystal molecules will be re-aligned to be parallel to the substrate and have a double refraction effect. For this reason, in the reflective display area and the transmissive display area, the circularly polarized light incident on the liquid crystal layer 50 is converted into elliptically polarized light during the process of being transmitted through the liquid crystal layer 50 . The incident light is not converted into linearly polarized light perpendicular to the transmission axis of the polarizing plate 37 even after passing through the retardation plate 36 , and all or part of it passes through the polarizing plate 37 . Therefore, in the liquid crystal display device of this embodiment, white display can be performed when a voltage is applied. In addition, gray scale display is also possible by adjusting the voltage applied to the liquid crystal layer 50 .

As described above, in the reflective display area, although the incident light is transmitted through the liquid crystal layer 50 twice, in the transmissive display area, the incident light is transmitted only once. In this case, when the optical path (retardation value) of the liquid crystal layer 50 is different between the reflective display area and the transmissive display area, as a result, a uniform image cannot be obtained due to a difference in light transmittance. show. However, in the liquid crystal display device of this embodiment, since the liquid crystal layer thickness adjustment layer 21 is provided, the optical length can be adjusted in the reflective display area. Therefore, uniform image display can be obtained in the reflective display area and the transmissive display area.

[Orientation control means]

16 is a plan view showing the configuration of one pixel region of the liquid crystal display device shown in FIG. 15 , in which components on the element substrate are indicated by solid lines, and components on the counter substrate are indicated by dashed-dotted lines. As shown in FIG. 16 , a plurality of slits 31 c (electrode cutouts) are formed on the pixel electrode 31 from the long side toward the center. In other words, the pixel electrode 31 arranged corresponding to one dot area is composed of three island-shaped sub-pixels 32 and a connecting portion connecting them, and the connecting portion is regarded as a place for substantially controlling the orientation of liquid crystal molecules. Slit 31c (notch of electrode). The pixel electrode 31 is divided into three sub-pixels 32 by the slit 31c, and each sub-pixel is connected by the central part. In addition, at least one sub-pixel among the three sub-pixels 32 is allocated to correspond to the reflective display area. Therefore, on the same substrate on which the pixel electrode 31 has been formed, the dielectric protrusion 18, the slit 31c, the dielectric protrusion 18, the slit 31c, and the dielectric protrusion 18 are arranged in the length (long side) direction of the pixel electrode 31 in this order. composition.

Further, on the surface of the pixel electrode 31 corresponding to the center portion of each sub-pixel 32 , a dielectric protrusion 18 is formed respectively. The dielectric protrusion 18 is formed in a substantially circular shape in plan view, and is formed in a substantially triangular shape in side view as shown in FIG. 15 . That is to say, the liquid crystal display device of this configuration example adopts the basic structure and function of the liquid crystal display device 200 of Embodiment 2 shown in FIG. The liquid crystal display device in which the slit 31c is provided on the same substrate.

A plurality of liquid crystal domains can be formed in one dot area by virtue of the electrode structure in which the above-mentioned sub-pixels have been formed. In addition, the corners of the sub-pixel 32 have been chamfered, and the sub-pixel 32 is formed into a substantially octagonal or substantially circular shape in plan view. In addition, when a voltage is applied to the liquid crystal layer, the liquid crystal molecules 51 are vertically tilted with respect to the outline of the sub-pixel 32 (edge portion 31a shown in FIG. 1). In addition, at the periphery of the dielectric protrusion 18, when no voltage is applied, the liquid crystal molecules 51 are aligned perpendicular to the slope of the dielectric protrusion 18, and when a voltage is applied, as shown in FIG. 16, the liquid crystal molecules 51 will face the dielectric. When the protrusions 18 are tilted, the liquid crystal molecules 51 are aligned radially with the dielectric protrusions 18 as the center plane.

Therefore, a plurality of directors of liquid crystal molecules can be produced, and a liquid crystal display device with a wide viewing angle can be provided. In addition, contrary to the above, slits and dielectric protrusions may be formed on the counter electrode 9 .

In the liquid crystal display device of this configuration example shown in FIGS. 15 and 16 , since the slits 31C and the dielectric protrusions 18 are provided on the pixel electrodes 31 , the element substrate 25 and the counter substrate 10 are arranged to sandwich the liquid crystal layer 50 . When they are bonded together, there is an advantage that alignment between the slit 31c and the dielectric protrusion 18 is unnecessary, and the manufacture of the liquid crystal display device is facilitated, and an improvement in yield can be expected.

(Electronic equipment)

Fig. 17 is a perspective view showing an example of the electronic device of the present invention. A mobile phone 1300 shown in this figure has a small-sized display portion 1301 using the liquid crystal display device of the present invention, a plurality of operation buttons 1302, a receiver port 1303, and a speaker port 1304.

The display device of each of the above-mentioned embodiments is not limited to the above-mentioned mobile phone, and can also be satisfactorily used as an electronic book, a personal computer, a digital still camera, a liquid crystal television, a video recorder of a viewfinder type or a monitor direct view type, a navigation device, Image display devices such as pagers, electronic notebooks, calculators, word processors, workstations, TV phones, POS terminals, devices with touch panels, etc., can display bright, high-contrast and wide Transmissive/reflective display of viewing angles.

Claims (3)

1. one kind is provided with the some zone that constitutes the unit of display, comprises that original state presents the liquid crystal indicator of vertical orientated liquid crystal layer, is characterized in that:

Above-mentioned some zone has the pixel electrode that comprises a plurality of sub-pixels,

Each sub-pixel is formed with connexon pixel coupling part and slit each other each other, and each subpixel configuration is had the dielectric projection,

With the time to above-mentioned liquid crystal applied voltages, the mode that above-mentioned liquid crystal on the straight line that connects the above-mentioned dielectric projection seen on the plane and above-mentioned slit is not toppled over round about is provided with the relation of the dielectric coefficient of the long axis direction of the dielectric coefficient of above-mentioned dielectric projection and above-mentioned liquid crystal and short-axis direction.

2. liquid crystal indicator according to claim 1 is characterized in that:

At the dielectric coefficient of establishing above-mentioned dielectric projection is ε _T1, the dielectric coefficient of establishing the long axis direction of above-mentioned liquid crystal is ε _∥, the dielectric coefficient of short-axis direction is ε _⊥The time, have ε _T1＞ε _∥Relation.

3. an electronic equipment is characterized in that: possess claim 1 or 2 described liquid crystal indicators.

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