JPH07253578A - Liquid crystal display - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a liquid crystal display device having a wide viewing angle that is unlikely to cause a decrease in contrast and an increase in drive voltage without significantly increasing the number of processes or equipment. [Structure] UV irradiation to the alignment film, printing of various alignment films,
A liquid crystal display device in which a high pretilt angle portion and a low pretilt angle portion are generated by rubbing treatment with varying rubbing strength and proper adjustment of a chiral agent, and the alignment of liquid crystal molecules in one pixel is made up of a plurality of domains. [Effect] A liquid crystal display device having a wide viewing angle can be realized by a liquid crystal display device having high and low pretilt angles by irradiating the alignment film with ultraviolet rays and printing various alignment films according to the present invention. It is possible to provide a high-definition liquid crystal display device that prevents the deterioration of contrast and reduces the driving voltage by introducing a high-dielectric-constant anisotropic liquid crystal, common voltage alternating current, and introducing active elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a wide viewing angle without gradation inversion.

[0002]

2. Description of the Related Art As a conventional liquid crystal display device having a wide viewing angle without gradation inversion, for example, an operation of rubbing a plurality of times by partially covering an alignment film in a pixel with a resist or the like and rubbing is repeated. , A method of dividing the alignment direction of the liquid crystal in the pixel (Japanese Patent Laid-Open No. 5-107544), a method of introducing a retardation plate (Japanese Patent Laid-Open No. 5-188367), and the twist direction of the liquid crystal is reversed in the same cell. Method (Japanese Patent Laid-Open No. 5-303118), method for producing bend mode of liquid crystal in liquid crystal cell (SID
'93Digest 277) etc.

[0003]

With respect to the prior art,
In the method of dividing the alignment direction of the liquid crystal in the pixel, rubbing a plurality of times may increase the number of steps, and the alignment film may be damaged or contaminated by a resist or the like. The method of merely introducing the retardation plate increases the number of steps of attaching the retardation plate, which requires alignment accuracy, and thus the cost increase cannot be avoided. In addition, a sufficient viewing angle widening effect may not be obtained in some cases. Problems such as instability of liquid crystal alignment, increase in the number of processes, decrease in contrast due to light leakage between domains, and increase in drive voltage are caused by a method that only reverses the twist direction of the liquid crystal within the same cell (reverse twist mode). Is included. The method of producing the bend mode of the liquid crystal in the liquid crystal cell has a problem that the alignment of the liquid crystal becomes unstable as compared with the usual 90 ° twist cell.

Therefore, an object of the present invention is to provide a plurality of orientation directions of liquid crystal molecules in one pixel without significantly increasing the number of steps, to obtain a good contrast, a high driving voltage, and a wide viewing angle. An object is to provide a liquid crystal display device.

[0005]

A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode faces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and the liquid crystal layer. In a liquid crystal display device including a pair of polarizing plates each having a polarization axis in a certain direction and sandwiched between the liquid crystal display device and a drive circuit for applying a voltage to the liquid crystal layer, the alignment film is irradiated with ultraviolet rays. To generate a high pretilt angle portion and a low pretilt angle portion so that the alignment of liquid crystal molecules in one pixel is composed of a plurality of domains, or a liquid crystal using an alignment film that lowers the pretilt angle by ultraviolet irradiation. The display device itself is a means for solving the problem.

The alignment film is produced by separately printing a high pretilt angle alignment film and a low pretilt angle alignment film by printing to generate a high pretilt angle part and a low pretilt angle part, and a plurality of liquid crystal molecules in one pixel are aligned. You may make it consist of the domain of.

The alignment film is formed by partially coating a low pretilt angle alignment film on a high pretilt angle alignment film by printing,
A high pretilt angle part and a low pretilt angle part are generated,
A means in which the orientation of liquid crystal molecules in one pixel is made up of a plurality of domains may be used.

Furthermore, when rubbing the alignment film, the rubbing strength is partially changed to generate a high pretilt angle portion and a low pretilt angle portion on the alignment film, and a plurality of liquid crystal molecules in one pixel are aligned. You may use the means which consists of the domain of.

When a right (left) twisted rubbing treatment is carried out in a TN cell and a liquid crystal containing a right (left) twisted chiral agent is enclosed, a plurality of domains containing several kinds of liquid crystal orientations are less likely to occur. A stable single domain is likely to occur. Therefore, when the right (left) twisted rubbing treatment is performed, it is desirable to use a liquid crystal containing a left (right) twisted chiral agent. At this time, since the twist direction of the liquid crystal is constituted by the chiral agent, it is desirable that the force that induces the twist of the chiral agent is large within the range of the TN cell, and the thickness (d) of the liquid crystal layer containing the chiral agent and The ratio (d / p) of chiral pitch (p) is 0.06 to 0.15
It is good to be in the range. Further, since the d / p size is deeply related to the generation of various domains, it is necessary to use a chiral agent whose chiral pitch does not greatly change with temperature so that the d / p size does not change with the environment. is there.

The ultraviolet irradiation can be carried out either before or after the rubbing treatment, but it is desirable to carry out the irradiation before the rubbing treatment in order to easily control the orientation. The wavelength of ultraviolet rays is 200 to 3 so as not to damage the alignment film too much.
The alignment film may be irradiated with another light source containing visible light or infrared light as long as it is selected from the range of 80 nm and the light of the wavelength in this range is included. As the alignment film, a high pretilt angle alignment film and a low pretilt angle alignment film are used, but when a means for irradiating ultraviolet rays is used, a high pretilt angle portion and a low pretilt angle portion can be formed even if one kind of alignment film is used.

The plurality of domains may include various types of domains such as a reverse twist mode and a reverse tilt mode, but it is desirable to set the reverse tilt mode so as to reduce light leakage from the domain boundary. When the high pretilt angle portion of one substrate and the low pretilt angle portion of the other substrate are opposed to each other, a reverse tilt mode domain is easily generated.

In order to reduce light leakage from the boundaries between the domains in the display section, means for vertically dividing the orientation of liquid crystal molecules in one pixel into two can be used so that the boundaries are as short as possible. The orientation of the liquid crystal molecules in one pixel may be divided into two or more so that regions of different orientations in the pixel are equally divided. In order to easily generate the domain of the reverse tilt mode, it is desirable to set the low pretilt angle to 0 to 2 ° and the difference between the high pretilt angle and the low pretilt angle to 3 ° or more. On the other hand, in addition to the high pretilt angle portion and the low pretilt angle portion, there may be a portion having a plurality of pretilt angles between them, which can promote the generation of various domains.

Light leakage at the domain boundary causes an increase in transmittance during black display, which increases the drive voltage. Therefore, a liquid crystal having a dielectric anisotropy of 7.0 (25 ° C.) or higher is used. Can be reduced. It is possible to prevent an increase in transmittance during black display by introducing at least one retardation plate between the pair of polarizing plates, and as a result, it is possible to reduce the driving voltage. The retardation Δnd (the product of the refractive index anisotropy Δn and the thickness d) of the retardation plate corrects the retardation of the light leakage, and is preferably 0.005 μm ≦ Δnd ≦ 0.2 μm.

To enable fine display of image quality, active elements can be arranged in a matrix on one of the electrodes. It is possible to reduce the driving voltage by having active elements in a matrix on one of the electrodes and applying an AC voltage to the other electrode. A color filter may be provided on one of the pair of substrates to enable color display.

[0015]

[Function] The alignment film is irradiated with ultraviolet rays, various alignment films are printed, and the rubbing strength is changed to generate a high pretilt angle portion and a low pretilt angle portion, so that the alignment of liquid crystal molecules in one pixel is prevented. The method of using a plurality of domains and the liquid crystal display device itself have an effect of improving the viewing angle by combining the vertical and horizontal viewing angle characteristics of a normal 90 ° twist cell. A desired pretilt angle can be given to an arbitrary region by using a mask by combining the irradiation condition and irradiation time of ultraviolet rays and the characteristics of the alignment film, and the damage of the alignment film can be suppressed. In addition, it is possible to easily form a state in which the above wide viewing angle is achieved by appropriately adjusting the chiral agent and appropriately facing the high pretilt angle portion and the low pretilt angle portion.

The reverse tilt mode domain reduces light leakage from the domain boundary. The means for dividing the orientation of the liquid crystal molecules in one pixel into upper and lower parts shortens the boundary between domains in the display portion, and can reduce the amount of light leakage. When the pixel is divided into a plurality of domains, the anisotropy of the viewing angle characteristic is further reduced.

The introduction of the retardation plate improves the contrast. The use of a liquid crystal having a dielectric anisotropy of 7.0 (25 ° C.) or more and a method of applying an AC voltage to one electrode act to reduce the driving voltage. High-definition display is possible by installing active elements in a matrix on one of the electrodes. Color display is possible by providing a color filter.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 shows the structure of a liquid crystal display device of this embodiment. FIG. 1 is a schematic sectional view of the liquid crystal display device of this embodiment. As shown in FIG. 1, transparent electrodes 40 and 41 are formed on optically transparent substrates 30 and 31, and polarizing plates 10 and 11 are arranged outside the substrates 30 and 31, respectively. In addition, alignment films 50, 51, 52, and 53 rubbed in one direction are provided inside the electrodes, and a nematic liquid crystal layer 60 is sandwiched between these alignment films.
Further, a drive circuit 90 connected to a power source for applying a voltage to the nematic liquid crystal layer 60 is connected to the transparent electrodes 40 and 41. The polarization axes of the polarizing plates on the same substrate are parallel to the rubbing direction, and the angle formed by the two polarization axes is 90 degrees.

RN-422 manufactured by Nissan Chemical Co., Ltd. was used as the alignment film, and the alignment film was baked at 250 ° C. for 30 minutes. Using a quartz mask on which chromium is vapor-deposited, only the alignment films 50 and 53 in FIG.
Irradiation with an intensity of 0 mJ / cm ² and a pretilt angle of about 1.5
It was processed to become °. The pretilt angle of the alignment films 51 and 52 is about 5.2 °. Figure 2 shows the rubbing direction.
As shown by 55 and 56 in (a), the upper and lower substrates are twisted to the right, and the high pretilt angle portion 51,
52 was assembled so as to face the low pretilt angle portions 50 and 53, and the peripheral portion was closed with a sealant except for the sealing port. After sealing the liquid crystal, the sealing port was sealed with a sealant. The liquid crystal contains 0.35% by weight of left-handed cholesteryl nonanate as a chiral agent and is ZLI4792 (Δn = 0.09) manufactured by Merck.
7) is used and the thickness of the nematic liquid crystal layer is 5.1 μm.
The Δnd of the nematic liquid crystal layer was 0.49 μm.
As the polarizing plate, G1220DU (polarization degree 99.95%) manufactured by Nitto Denko was used.

In the present embodiment, the orientation of the liquid crystal in the pixel is one pixel (200 × 100 μm) as shown in FIG.
In m), it is divided into two by two domains. The arrows 61 and 63 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62 and 64 indicated by dotted lines indicate the alignment directions of the liquid crystal molecules near the lower substrate, and the directions of the arrows have a pretilt angle. Each domain is a reverse tilt mode domain.

In a normal TN cell, the viewing angle in the vertical direction at which the contrast is 5 or more and gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

[Embodiment 2] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

Using a quartz mask with chromium vapor deposited,
By controlling the ultraviolet irradiation area, in the present embodiment, the orientation of the liquid crystal in the pixel is divided into two vertically by two domains in one pixel as shown in FIG. The arrows 61 and 63 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62 and 64 indicated by dotted lines indicate the alignment directions of the liquid crystal molecules near the lower substrate, and the directions of the arrows have a pretilt angle. Each domain is a reverse tilt mode domain.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained. Further, the amount of light leakage at the domain boundary was smaller than that in Example 1, and the occurrence of domains other than the reverse tilt mode when a high voltage was applied was also small.

[Embodiment 3] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

Using a quartz mask on which chromium is deposited,
By controlling the ultraviolet irradiation area, the alignment of the liquid crystal in the pixel in this embodiment is multi-divided by a plurality of domains in one pixel as shown in FIGS. 5 (a) and 5 (b).
Arrows 61, 63, 65 and 67 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62, 64, 6 indicated by dotted lines
Reference numerals 6 and 68 denote the alignment directions of the liquid crystal molecules near the lower substrate, which have pretilt angles in the directions of the arrows.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained. Further, the variation in the contrast between the pixels was smaller than that in the first embodiment.

[Embodiment 4] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

In FIG. 1, RN-1008 manufactured by Nissan Chemical Co., Ltd. was applied to the alignment films 50 and 53 by printing, and RN-1006 manufactured by Nissan Chemical Co., Ltd. was applied to the alignment films 51 and 52 by printing.
After baking at 180 ° C. for 10 minutes, rubbing treatment is performed in the direction of FIG. 2A, and the pretilt angle of the alignment films 50 and 53 is about 1.
At 9 °, the pretilt angle of the alignment films 51 and 52 was set to about 6.8 °. The size of one pixel is 2 x 1 mm
Is.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 3 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

[Embodiment 5] The liquid crystal display device of this embodiment is the same as that of Embodiment 4 except for the following conditions.

In FIG. 6, RN-1008 manufactured by Nissan Chemical Co., Ltd. is applied by printing on the entire surface of the alignment films 50 and 53, and 180 ° C.
It was baked for 5 minutes. Further, RN-1006 manufactured by Nissan Chemical Co., Ltd. was applied to the alignment films 51 and 52 by printing. 180 ° C 5
After the minute baking, a rubbing treatment is performed in the direction of FIG. 2A, the pretilt angle of the alignment films 50 and 53 is about 1.9 °, and the pretilt angle of the alignment films 51 and 52 is about 6.8 °. I tried to become. The size of one pixel is 2 × 1 mm.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 3 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained. Further, the alignment film coating required for printing accuracy was performed once, and the number of defective products was reduced as compared with the case of Example 5.

[Embodiment 6] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

The alignment film was prepared by mixing and applying LQ1800 manufactured by Hitachi Chemical Co., Ltd. and PIQ, and baking at 250 ° C. for 30 minutes. As shown in FIG. 7, the alignment film shows a phase separation state, and after rubbing, the alignment film has a high pretilt angle portion 51, 52 (pretilt angle about 4.5 °) and a low pretilt angle portion 50, 53 (pretilt angle about 50 °). 1.2 °) occurred. The rubbing direction was set so that it was twisted rightward as indicated by 55 and 56 in FIG.

In this embodiment, the orientation of the liquid crystal in each pixel is multi-divided by a plurality of domains in one pixel (200 × 100 μm) as shown in FIG. Arrows 61, 63, 65 and 67 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62, 64, 66, and 68 indicated by dotted lines indicate the alignment directions of liquid crystal molecules near the lower substrate, and have pretilt angles in the directions of the arrows. Each domain is a mixture of reverse tilt mode domain and reverse twist mode domain.

In a normal TN cell, the viewing angle in the vertical direction at which the contrast is 5 or more and gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 3 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

[Embodiment 7] The liquid crystal display device of this embodiment is the same as that of Embodiment 6 except for the following conditions.

The alignment film is LQ1800, LQ5000X manufactured by Hitachi Chemical Co., Ltd.
RN199 made by Nissan Chemical Co., Ltd. is mixed and applied, 250 ° C. 3
Bake for 0 minutes. As shown in FIG. 7, the alignment film shows a phase-separated state, and after rubbing, the alignment film has a high pretilt angle portion 5.
1, 52 (pretilt angle of about 4.5 to 5 °) and low pretilt angle portions 50 and 53 (pretilt angle of about 1.7 °) were generated. The rubbing direction was set so that it was twisted rightward as indicated by 55 and 56 in FIG.

In this embodiment, the orientation of the liquid crystal in each pixel is multi-divided by a plurality of domains in one pixel (200 × 100 μm) as shown in FIG. Arrows 61, 63, 65 and 67 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62, 64, 66, and 68 indicated by dotted lines indicate the alignment directions of liquid crystal molecules near the lower substrate, and have pretilt angles in the directions of the arrows.

Each domain is a mixture of a reverse tilt mode domain and a reverse twist mode domain.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 3 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

[Embodiment 8] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

The rubbing direction is left twisted as indicated by 57 and 58 in FIG. 2B, and the upper and lower substrates are arranged so that the high pretilt angle portions 51 and 52 of the alignment film are the low pretilt angle portions 50 and 53. They were assembled so as to face each other, and the peripheral portion was closed with a sealant except for the sealing port. After sealing the liquid crystal, the sealing port was sealed with a sealant. As the liquid crystal, ZLI4792 (Δn = 0.097) manufactured by Merck Co., Ltd. containing 0.5% by weight of right-twisted S1082 manufactured by Merck Co., Ltd. was used as a chiral agent.

In the present embodiment, the orientation of the liquid crystal in the pixel is one pixel (200 × 100 μm) as shown in FIG.
In m), it is divided into two by two domains. Arrows 65 and 67 indicated by solid lines indicate the alignment direction of liquid crystal molecules near the upper substrate, and have a pretilt angle in the direction of the arrow. Similarly, arrows 66 and 68 indicated by dotted lines indicate the alignment directions of the liquid crystal molecules near the lower substrate, and the directions of the arrows have a pretilt angle. Each domain is a reverse tilt mode domain.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

[Embodiment 9] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

As the alignment film, RN-422 manufactured by Nissan Chemical Co., Ltd. was used and baked at 250 ° C. for 30 minutes. Using a quartz mask on which chromium is vapor-deposited, only a portion of the alignment films 50 and 53 in FIG.
The film was irradiated with light having a wavelength of nm at an intensity of 1 mJ / mm ² , and the pretilt angle was adjusted to about 1.3 °. The pretilt angle of the alignment films 51 and 52 is about 5.2 °. The rubbing direction is twisted rightward as indicated by 55 and 56 in FIG. 2A, and the upper and lower substrates are arranged so that the high pretilt angle portions 51 and 52 of the alignment film face the low pretilt angle portions 50 and 53. Then, the peripheral portion was closed with a sealant except for the sealing port. After sealing the liquid crystal, the sealing port was sealed with a sealant. The liquid crystal is a left-handed Merck S-811 as a chiral agent.
ZLI4792 (Δn = 0.09) containing 0.1% by weight of
7) is used, and the thickness of the nematic liquid crystal layer is 5.3 μm
The Δnd of the nematic liquid crystal layer was 0.50 μm.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

[Embodiment 10] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the conditions described below.

The liquid crystal is a Chisso HA50 containing 0.35% by weight of left-handed cholesteryl nonanate as a chiral agent.
58LA (Δn = 0.073) is used, the thickness of the nematic liquid crystal layer is 5.5 μm, and the Δnd of the nematic liquid crystal layer is 0.4.
It was set to 0 μm.

Using a quartz mask with chromium vapor deposited,
By controlling the ultraviolet irradiation area, in the present embodiment, the alignment of the liquid crystal in the pixel was divided into two vertically by two domains in one pixel as shown in FIG. The arrows 61 and 63 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62 and 64 indicated by dotted lines indicate the alignment directions of the liquid crystal molecules near the lower substrate, and the directions of the arrows have a pretilt angle.
Each domain is a reverse tilt mode domain.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained. Also, the contrast of 10
The drive voltage for obtaining 0 was 3.8 V, which was about 1.2 V lower than that of Example 2, and the drive voltage was reduced.

[Embodiment 11] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

The structure of the liquid crystal display device of this embodiment is shown in FIG. FIG. 9 is a schematic sectional view of the liquid crystal display device of this embodiment. As shown in FIG. 9, optically transparent substrates 30, 31
Transparent electrodes 40 and 41 are formed on the substrates 30 and 3
Polarizing plates 10 and 11 are arranged outside 1 respectively. Further, the retardation plate 20 is disposed between the polarizing plate 10 and the substrate 30, and the alignment films 50, 51, 52, 53 rubbed in one direction are provided inside the electrodes, and the nematic layer is interposed between these alignment films. The liquid crystal layer 60 is held. Further, a driving circuit 90 connected to a power source for applying a voltage to the nematic liquid crystal layer 60 is connected to the transparent electrodes 40 and 41. The polarization axes of the polarizing plates on the same substrate are parallel to the rubbing direction, and the angle formed by the two polarization axes is 90 degrees.
As the retardation plate 20, two uniaxially stretched polycarbonate films having Δnd of 0.56 μm and 0.50 μm are used.
The film was formed by laminating the films so that the stretching directions were orthogonal to each other.
The total Δ of the retardation plate 20 composed of the two films
nd is 0.06 μm and the optical axis is in the stretching direction of the film having Δnd of 0.56 μm. This phase plate 20
The optical axis of is the direction of the vector sum of two rubbing directions and 9
It was arranged so as to form an angle of 0 °.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained. Further, the transmittance of black display can be reduced by the retardation plate, and the contrast can be improved at an angle of 10 ° or more in the vertical and horizontal directions as compared with the case of the first embodiment.

[Embodiment 12] The liquid crystal display device of this embodiment is the same as embodiment 11 except for the following conditions.

The structure of the liquid crystal display device of this embodiment is shown in FIG. FIG. 10 is a schematic sectional view of the liquid crystal display device of this embodiment. Optically transparent substrates 30, 3 as shown in FIG.
Transparent electrodes 40, 41 are formed on the substrate 1,
Polarizing plates 10 and 11 are arranged outside of 31 respectively.
In addition, the retardation plates 20 and 21 are arranged between the polarizing plates 10 and 11 and the substrates 30 and 31, and the alignment films 50, 51, 52 and 53 rubbed in one direction are provided inside the electrodes. The nematic liquid crystal layer 60 is sandwiched between the alignment films. Further, a driving circuit 90 connected to a power source for applying a voltage to the nematic liquid crystal layer 60 is connected to the transparent electrode 40,
It is connected to 41. The polarization axes of the polarizing plates on the same substrate are parallel to the rubbing direction, and the angle formed by the two polarization axes is 90 degrees. The retardation plates 20 and 21 have Δnd of 0.
The uniaxially stretched polycarbonate film of 06 μm and 0.08 μm is used, and the optical axis of the retardation plate 20 and the alignment film 5 are used.
The rubbing directions of 0 and 51 are 90 degrees, and the optic axis of the retardation plate 21 and the rubbing directions of the alignment films 52 and 53 are 90 degrees.

In a normal TN cell, the viewing angle in the vertical direction at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 5 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained. Further, the transmittance of black display can be reduced by the retardation plate, and the contrast can be improved at an angle of 20 ° or more in the vertical and horizontal directions as compared with the case of the first embodiment. Further, the front contrast is improved and the driving voltage can be reduced. By controlling Δnd of the retardation film, Δnd of the liquid crystal display device can be adjusted, and a bright liquid crystal display device is enabled.

[Embodiment 13] The liquid crystal display device of this embodiment is the same as embodiment 11 except for the following conditions.

The structure of the liquid crystal display device of this embodiment is shown in FIG. FIG. 11 is a schematic sectional view of the liquid crystal display device of this embodiment. As shown in FIG. 11, a transparent common electrode 40 is formed on an optically transparent substrate 30, an active element 42 that switches the applied voltage for each pixel is provided on the substrate 31, and a common voltage circuit 91, a scanning voltage, Signal voltage circuit 9
2. The circuit 91, 92 is provided with a supply source 93 for supplying a control signal, a data signal and a power supply voltage. The substrates 30, 3
Polarizing plates 10 and 11 are arranged outside 1 respectively. Further, the retardation plate 20 is disposed between the polarizing plate 10 and the substrate 30, and the alignment films 50, 51, 52, 53 rubbed in one direction are provided inside the electrodes, and the nematic layer is interposed between these alignment films. The liquid crystal layer 60 is held between the two. The polarization axes of the polarizing plates on the same substrate are parallel to the rubbing direction, and the angle formed by the two polarization axes is 90 degrees. The retardation plate 20 was formed by laminating two uniaxially stretched polycarbonate films having Δnd of 0.60 μm and 0.50 μm, and laminating the films so that the stretching directions thereof were orthogonal to each other. The total Δnd of the retardation plate 20 composed of the two films is 0.10 μm, and the film having the Δnd of 0.60 μm has an optical axis in the stretching direction. The optical axis of the retardation plate 20 is arranged so as to form an angle of 90 ° with the vector sum direction of the two rubbing directions.

In the present embodiment, as in the case of Embodiment 11, the viewing angle in the vertical direction is wider than that of the normal TN cell, and the contrast can be improved by the retardation plate.
Moreover, the active element has made it a high-speed liquid crystal display device with high resolution. Furthermore, by applying an AC voltage of 6.0 V to the common electrode 40, the voltage applied to the active element 42 can be suppressed to 4.2 V or less, and the driving voltage can be reduced. It is also possible to provide a bright liquid crystal display device by adjusting Δnd.

[Embodiment 14] The liquid crystal display device of this embodiment is the same as that of embodiment 13 except for the following conditions.

The structure of the liquid crystal display device of this embodiment is shown in FIG. FIG. 12 is a schematic sectional view of the liquid crystal display device of this embodiment. A color filter 70 is provided between the substrate 30 and the electrode 40, and the other configurations are similar to those of the thirteenth embodiment.

Similar to the thirteenth embodiment, this embodiment has a wider viewing angle in the vertical direction than the normal TN cell, the contrast can be improved by the phase difference plate, and the active element provides a high-speed response and high definition. It became a liquid crystal display device. Further, by applying an AC voltage of 6.0 V to the common electrode 40, the voltage applied to the active element 42 can be suppressed to 4.2 V or less, and the driving voltage can be reduced. Furthermore, by installing a color filter, it becomes possible to obtain a display with clear and excellent color display.

[Embodiment 15] The liquid crystal display device of this embodiment is the same as that of Embodiment 1 except for the following conditions.

As the alignment film, LXS302 manufactured by Hitachi Chemical Co., Ltd. is used.
It was baked at 90 ° C. for 10 minutes. Using a rayon rubbing cloth in which 1.6 mm and 1.3 mm long bristles are alternately arranged in a stripe pattern, the rubbing direction is right as shown by 55 and 56 in Fig. 2 (a). The rubbing was performed so that it would be twisted. As a result, a high pretilt portion (pretilt angle of about 5.1 °) and a low pretilt angle portion (pretilt angle of about 2.0 °) were generated in the alignment film. The upper and lower substrates were assembled and the same liquid crystal as in Example 1 was sealed and sealed.

In this embodiment, the orientation of the liquid crystal in the pixel is divided by a plurality of domains in one pixel 000 (2 × 2 mm) as shown in FIG. 5 (c). Arrows 61, 63, and 65 indicated by solid lines indicate the alignment directions of the liquid crystal molecules near the upper substrate, and the directions of the arrows have a pretilt angle. Similarly, arrows 62, 64, and 66 indicated by dotted lines indicate the alignment directions of the liquid crystal molecules near the lower substrate, and the directions of the arrows have a pretilt angle.

In a normal TN cell, the vertical viewing angle at which the contrast is 5 or more and the gradation is not reversed is about 1 in the upward direction.
The angle was 5 ° and about 20 ° in the downward direction, whereas it was 40 ° or more in the vertical direction in the liquid crystal display device of this example. The range in which the gradation is not reversed at a contrast of 3 or more is ± 40 ° or more in the horizontal direction, and a liquid crystal display device having a wide viewing angle can be obtained.

The liquid crystal display device of the present invention can be used as a display device for notebook personal computers, laptop computers, word processors, workstations, televisions, in-vehicle displays, etc.
The liquid crystal display device of the present invention can also be used in a projector.

[0072]

According to the present invention, a liquid crystal display device having a wide viewing angle can be realized by a liquid crystal display device having high and low pretilt angles generated by irradiating the alignment film with ultraviolet rays and printing various kinds of alignment films. A plate, a high-dielectric-constant anisotropic liquid crystal, a common voltage alternating current, and the introduction of an active element prevent a reduction in contrast, reduce a driving voltage, and can provide a high-definition liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

2A and 2B are views showing rubbing directions according to an embodiment of the present invention.

3A and 3B are diagrams showing alignment states of liquid crystals in a pixel portion from above the liquid crystal display device in one embodiment of the present invention.

FIG. 4 is a diagram showing an alignment state of liquid crystals in a pixel portion from above the liquid crystal display device in one embodiment of the present invention.

5A, 5B, and 5C are diagrams showing alignment states of liquid crystals in a pixel portion from above the liquid crystal display device in one embodiment of the present invention.

FIG. 6 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 7 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 8 is a diagram showing an alignment state of liquid crystals in a pixel portion from above the liquid crystal display device in one embodiment of the present invention.

FIG. 9 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 10 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 11 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 12 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

[Explanation of symbols]

10, 11 ... Polarizing plate, 20, 21 ... Retardation plate, 30, 3
1 ... Substrate, 40, 41 ... Electrode, 42 ... Active element,
50, 51, 52, 53 ... Alignment film, 55, 56, 57,
58 ... Rubbing direction, 60 ... Nematic liquid crystal layer, 61,
63, 65, 67 ... Orientation direction of liquid crystal molecules near the upper substrate,
62, 64, 66, 68 ... Alignment direction of liquid crystal molecules near the lower substrate, 70 ... Color filter, 90 ... Driving circuit, 91 ...
Common voltage supply circuit, 92 ... Scanning and signal voltage supply circuit, 93 ... Control signal, data signal, power supply voltage supply source.

Claims (15)

[Claims] 1. A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode faces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and a liquid crystal layer sandwiched therebetween. In a liquid crystal display device including a pair of polarizing plates each having a polarization axis in one direction and a drive circuit for applying a voltage to the liquid crystal layer, a part of the alignment film is irradiated with ultraviolet rays. A liquid crystal display device, characterized in that a high pretilt angle portion and a low pretilt angle portion are generated, and the alignment of liquid crystal molecules in one pixel is constituted by a plurality of domains. 2. A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode faces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and a liquid crystal layer sandwiched therebetween. In a liquid crystal display device including a pair of polarizing plates each having a polarization axis in one direction and a drive circuit for applying a voltage to the liquid crystal layer, a pretilt angle is reduced by irradiating ultraviolet rays. A liquid crystal display device using an alignment film, wherein a difference in pretilt angle is generated between a part irradiated with ultraviolet rays and a part not irradiated with ultraviolet rays, and the alignment of liquid crystal molecules in one pixel is composed of a plurality of domains. 3. A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode faces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and a liquid crystal layer sandwiched therebetween. In a liquid crystal display device comprising a pair of polarizing plates each having a polarization axis in a certain direction, and a drive circuit for applying a voltage to the liquid crystal layer, the alignment film is a high pretilt angle alignment film formed by printing. And a low pretilt angle alignment film are separately applied to produce a high pretilt angle portion and a low pretilt angle portion, and the alignment of liquid crystal molecules in one pixel is constituted by a plurality of domains. . 4. A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode surfaces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and a liquid crystal layer sandwiched therebetween. In a liquid crystal display device comprising a pair of polarizing plates each having a polarization axis in a certain direction, and a drive circuit for applying a voltage to the liquid crystal layer, the alignment film is a high pretilt angle alignment film formed by printing. A liquid crystal display characterized in that a low pretilt angle alignment film is partially applied on the upper part to generate a high pretilt angle part and a low pretilt angle part, and the alignment of liquid crystal molecules in one pixel is composed of a plurality of domains. apparatus. 5. A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode surfaces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and a liquid crystal layer sandwiched therebetween. In a liquid crystal display device including a pair of polarizing plates each having a polarization axis in one direction and a drive circuit for applying a voltage to the liquid crystal layer, the alignment film causes phase separation and It consists of an alignment film composed of multiple types of polymer components that generate a pretilt angle and a low pretilt angle. It produces a high pretilt angle portion and a low pretilt angle portion, and the alignment of liquid crystal molecules in one pixel is in multiple domains. A liquid crystal display device comprising: 6. A pair of substrates having electrodes on opposite surfaces, an alignment film arranged on the electrode surfaces of the pair of substrates, a liquid crystal layer sandwiched between the alignment films, and a liquid crystal layer sandwiched therebetween. In a liquid crystal display device including a pair of polarizing plates each having a polarization axis in a certain direction and a drive circuit for applying a voltage to the liquid crystal layer, a partial portion is formed when rubbing the alignment film. A liquid crystal display device characterized in that the rubbing intensity is changed to generate a high pretilt angle portion and a low pretilt angle portion so that the alignment of liquid crystal molecules in one pixel is constituted by a plurality of domains. 7. The high pretilt angle portion of the alignment film on one substrate of the pair of substrates according to claim 2 and the low pretilt angle portion of the alignment film on the other substrate are opposed to each other. Characteristic liquid crystal display device. 8. When the rubbing treatment is performed on the alignment film according to any one of claims 2 to 6, the liquid crystal molecules are twisted right (left) when viewed from above the panel in a 90 ° twist (TN) cell. A liquid crystal display device, characterized in that the liquid crystal contains a left (right) twisted chiral agent by rubbing in a direction. 9. A ratio (d) between the thickness (d) of the liquid crystal layer containing the chiral agent according to claim 8 and the chiral pitch (p).
/ P) is in the range of 0.06 to 0.15. 10. A liquid crystal display device, wherein the alignment film according to claim 1 or 2 is irradiated with the ultraviolet light before rubbing treatment. 11. The wavelength of the ultraviolet ray according to claim 2 is 20.
A liquid crystal display device, which has a thickness of 0 to 380 nm. 12. A liquid crystal display device, wherein the plurality of domains according to claim 2 are reverse tilt mode domains. 13. A liquid crystal display device according to claim 2, wherein the alignment of liquid crystal molecules in the one pixel is divided into two or more. 14. A liquid crystal display device according to claim 2, wherein the low pretilt angle is 0 to 2 ° and the difference between the high pretilt angle and the low pretilt angle is 3 ° or more. 15. A liquid crystal display device comprising an active element in a matrix on one of the electrodes according to any one of claims 2 to 6.