JPH09292519A - Optical compensation plate and liquid crystal display device formed by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the visual field angle characteristics of a liquid crystal display device by using optical compensation plates which are formed with layers contg. compds. having optically negative uniaxiality on transparent substrates and are continuously changed in the declination and inclination angle of the optical axes of these compds. both in the thickness direction of the substrates. SOLUTION: The optical compensation plates 42, 44 are formed with the layers contg. the compds. having the optically negative uniaxiality on the transparent substrates. The inclination angle of the optical axes of the compd. is so changed as to be 85 deg. from the normal direction of the substrates on the substrate side of the layers and to be 0 deg. on the counter substrate side. Further, the declination of the optical axes is so oriented as to change continuously until the declination 18 twisted 45 deg. from the substrate side toward the counter substrate side of the layers. Such optical compensation plates 42, 44 are respectively arranged between the cells 43 and polarizing plates 41, 45 of the liquid crystal display device consisting of the twisted nematic type liquid crystal cell 43 having a twist angle of 90 deg. and two sheets of the polarizing plates 41, 45 arranged on both sides of the cell 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optical compensator used in a liquid crystal display device and the like, and a twisted nematic liquid crystal display device using the same.

[0002]

2. Description of the Related Art Liquid crystal display devices have been increasingly used in portable televisions, notebook personal computers, etc. due to their features such as light weight, thin shape and low power consumption. Among them, TN type liquid crystal display driven by active matrix which is superior in image quality. The adoption of devices (hereinafter referred to as AM-TN-LCDs) has greatly increased. The AM-TN-LCD has come to be able to obtain image quality exceeding CRT when viewed from the front due to technical improvements so far, but it has a decrease in contrast and a change in hue when viewed from an oblique direction. Since the viewing angle characteristics are not sufficient as compared with the CRT, this improvement is strongly desired.

The viewing angle characteristics of the AM-TN-LCD are mainly due to the angle dependence of birefringence of the oriented liquid crystals in the liquid crystal cell. Due to this birefringence, the contrast increases as the angle from the front increases. At the same time, when gradation display is performed, gradation inversion occurs in which gradations are replaced with each other, and the hue changes greatly, making it difficult to see the display. In order to solve this problem, studies have been widely conducted to introduce an optical compensation layer such as a retardation plate to compensate the angle dependency of birefringence and improve the viewing angle characteristics. For example, JP-A-6-331
Japanese Patent Publication No. 979 discloses a method of arranging a compensating layer having negative refractive index anisotropy between a pair of polarizing plates, and Japanese Patent Laid-Open No. 6-250166 discloses a substantially negative refractive index. A method of using an optical retardation element in which a twisted nematic liquid crystal twisted in a spiral shape so as to have anisotropy is further tilted with respect to the substrate is disclosed. Further, in JP-A-6-214116, there is a negative refractive index anisotropy, and the optical axis is 10 with respect to the sheet surface.
A method using an optical anisotropic element tilted by -40 degrees is disclosed.

[0004]

However, although the viewing angle characteristics of the AM-TN-LCD are greatly improved by these methods, even when these methods are used, the viewing angle characteristics in a specific direction, particularly the main viewing angle direction, are improved. Improvement in gradation inversion is not always sufficient, and improvement in viewing angle characteristics in these directions is also desired. As a result of intensive studies to solve such a problem, a layer containing a compound having optically negative uniaxiality is formed on a transparent substrate, and the azimuth angle of the optical axis of the compound and the substrate normal direction The present invention has been found out that an optical compensator in which both of the tilt angles of 1) continuously change in the thickness direction of the substrate has an effect of improving the viewing angle characteristics of the AM-TN-LCD.

[0005]

Means for Solving the Problems That is, the present invention is as follows. (1) A layer containing a compound having optically negative uniaxiality is formed on a transparent substrate, and the azimuth angle of the optical axis of the compound and the inclination angle from the substrate normal direction are both the thickness of the substrate. An optical compensator characterized by continuously changing with respect to a direction. (2) The direction of the optical axis of the compound having optically negative uniaxiality is different on the substrate side of the layer, on the side opposite to the substrate and on the center of the layer, and the tilt angle of the optical axis is the substrate method on the side of the layer substrate. 50 ° to 90 ° from the line direction, and 0 ° on the non-substrate side
The azimuth angle of the optical axis is continuously changed so as to be twisted by about 45 ° or −45 ° from the substrate side of the layer toward the anti-substrate side. The optical compensator according to (1) above. (3) The direction of the optical axis of the compound having optically negative uniaxiality is different on the substrate side of the layer, the anti-substrate side, and the central portion of the layer, and the inclination angle of the optical axis is the substrate side of the layer and the anti-substrate. On the side, it is 5 ° to 50 ° from the substrate normal direction, and it changes continuously at about 90 ° in the center of the layer,
Further, the azimuth angle of the optical axis continuously changes from the substrate side of the layer to the opposite substrate side so as to be twisted by about 90 ° or about −90 °, and the optical compensator according to (1) above. . (4) Optical compensation according to the above (1), (2) or (3), wherein the compound having optically negative uniaxiality is an organic compound having a discotic molecular structure exhibiting liquid crystallinity. Board. (5) The optically negative uniaxial compound is an organic compound having a discotic molecular structure exhibiting liquid crystallinity, and
The optical compensator according to (4) above, wherein the discotic compound is used in combination with a chiral dopant. (6) A compound having an optically negative uniaxiality is an organic compound having a discotic molecular structure and exhibiting liquid crystallinity, and the discotic compound has a discotic molecular structure and liquid crystallinity. The optical compensator according to (4) above, which is used in combination with an organic compound having a substituent which is not shown and exhibits optical activity. (7) The optically negative uniaxial compound is an organic compound having a discotic molecular structure exhibiting liquid crystallinity, and
The optical compensator according to (4) above, wherein the discotic compound has a substituent exhibiting optical activity. (8) The compound having optically negative uniaxiality is an organic compound which does not exhibit liquid crystallinity and is oriented so as to exhibit negative refractive index anisotropy by an electric field or a magnetic field. ), (2) or (3) described above. (9) A twisted nematic liquid crystal display device using at least one optical compensating plate described in (1) above. (10) A normally white mode liquid crystal display device comprising a twisted nematic liquid crystal cell having a twist angle of about 90 ° and two polarizing plates arranged on both sides of the cell, wherein the optical compensating plate according to (2) above. A liquid crystal display device in which one cell is used between the cell and the polarizing plates on both sides. (11) A normally white mode liquid crystal display device comprising a twisted nematic liquid crystal cell having a twist angle of about 90 ° and two polarizing plates arranged on both sides of the cell, wherein the optical compensation plate according to (3) above A liquid crystal display device in which one sheet is used between the cell and one of the polarizing plates. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The azimuth angle of the optical axis of a compound having optically negative uniaxiality in the present invention means the direction in which the optical axis of the compound is orthographically projected on the substrate surface. Further, the tilt angle of the optical axis of the compound having optically negative uniaxiality refers to the angle formed by the direction of the optical axis of the compound and the normal line direction of the substrate surface. This will be described with reference to FIG. 1 is the optical axis direction of the compound having negative uniaxiality, 6 is the orthogonal projection direction of the optical axis on the substrate surface, 2, 3, 4, and 5 are azimuth angles of 0 ° direction, 90 ° direction, and 180 °, respectively. Shows a 270 ° direction and a azimuth angle of the optical axis. Reference numeral 8 indicates the normal direction of the substrate, and the angle 9 formed between this and the optical axis direction of 1 indicates the inclination angle of the optical axis.

The compound having an optically negative uniaxial property in the present invention means a negative refractive index anisotropy in which the refractive index in the optical axis direction is smaller than the average refractive index in a plane perpendicular to the compound when oriented. And the orientation angle of the optical axis and the inclination angle from the substrate normal direction can be aligned continuously with respect to the thickness direction of the substrate by some orientation means, there is no particular limitation. A compound, especially a compound having a discotic molecular structure exhibiting liquid crystallinity, and a compound not exhibiting liquid crystallinity but oriented so as to exhibit negative refractive index anisotropy by an electric field or a magnetic field are preferably used.

As the organic compound having a discotic molecular structure exhibiting liquid crystallinity, a low molecular weight or high molecular weight discotic liquid crystal, for example, triphenylene, torqcene, benzene or the like having an alkyl group, an alkoxy group in a mother nucleus having a planar structure, An example is one in which a linear substituent such as a substituted benzoyloxy group is radially bonded, but one that does not absorb in the visible light region is preferable.

Of these organic compounds having a disk-shaped molecular structure, not only one kind of them may be used alone, but also several kinds of them may be mixed and used in order to obtain the orientation necessary for the present invention. Alternatively, it can be used as a mixture with another organic compound such as a polymer matrix. The organic compound used as a mixture as described above has compatibility with an organic compound having a disk-shaped molecular structure, or an organic compound having a disk-shaped molecular structure can be dispersed to a particle size not to scatter light. There is no particular limitation as long as it exists.

Further, in order to obtain an orientation in which both the azimuth angle of the optical axis and the inclination angle from the substrate normal direction, which are necessary for the present invention, continuously change with respect to the thickness direction of the substrate, a disk shape is required. As the organic compound having the above-mentioned molecular structure, it is preferable to use an organic compound having a substituent having an optically active property which exhibits twist orientation in itself. Examples of the organic compound having a discotic molecular structure and a substituent exhibiting optical activity include C.I. Report of Destrade et al., PHYSICS LETTERS 79, 189
(+) Or (-)-2,3,6, described on the page
7,10,11-hexa- (3-methylnonanoyloxy) triphenylene, (+) or (-)-2,3
7,8,12,13-hexa- (3-methylnonanoyloxy) torcocene, and J. Malthete et al., Mol. Cryst. Liq. Crys
t. 64, 233, (+)-2,3,
6,7,10,11-hexa- (S- (4-methyl)-
Discotic liquid crystals having an optically active group such as 4-n-hexyloxybenzoyloxy) triphenylene can be mentioned.

As another method of exhibiting the twist orientation, it is desirable to impart the twist orientation by using an organic compound having a discotic molecular structure in combination with a chiral dopant. In this case, the chiral dopant generally refers to those used for imparting twist alignment to nematic liquid crystals in TN type liquid crystal cells, STN type liquid crystal cells and the like, and S-1 manufactured by MERCK
011 (ZLI-4571), R-1011 (ZLI-
4572), S-811 (ZLI-811) manufactured by the same company, R
-811 (ZLI-3786), and commonly known C15, CB15, and CN can be exemplified. There is no particular limitation on the amount of the chiral dopant added, and the amount may be adjusted so that the required twist orientation is obtained. The twist direction is not particularly limited, and the optical activity of the added chiral dopant may be selected and used so that the twist direction is suitable for improving the viewing angle characteristics of the combined liquid crystal cell.

Further, as another method of exhibiting the twist orientation, an organic compound having a discotic molecular structure and exhibiting liquid crystallinity is used, which has a discotic molecular structure and does not exhibit liquid crystallinity and exhibits optical activity. Twist orientation can also be imparted by using together with an organic compound having a substituent. Examples of the organic compound having a discotic molecular structure, exhibiting no liquid crystallinity, and having an optically active substituent include C.I. Dest
Research report by Rade et al., PHYSICS LETTER
S 79, 189, (+) or (-)-2,3,6,7,10,11-hexa- (3-
Methylnonanoyloxy) benzene etc. can be mentioned.

Further, for a compound which does not exhibit liquid crystallinity but is oriented so as to exhibit negative refractive index anisotropy by an electric field or magnetic field, the azimuth angle of the optical axis required for the present invention can be adjusted by applying an electric field or magnetic field. Any orientation can be used as long as the orientation can be such that both the inclination angle from the substrate normal direction and the thickness direction of the substrate continuously change.

Particularly, the orientation direction for obtaining the orientation necessary for the present invention such that both the azimuth angle of the optical axis and the inclination angle from the substrate normal direction continuously change in the thickness direction of the substrate is used. Not limited. For example, in the case of using a compound having liquid crystallinity, a method generally used for aligning liquid crystals, that is, a liquid crystal compound having twisted alignment as described above is aligned using a specific alignment film. Alternatively, a method of applying an electric field, a magnetic field, or the like to orient the compound can be used. Further, even when a compound having no liquid crystallinity is used, it is possible to achieve the required alignment by applying an electric field, a magnetic field or the like.

As the orientation in which the azimuth angle of the optical axis and the tilt angle from the substrate normal direction both continuously change in the thickness direction of the substrate of the present invention, an optically negative uniaxial property is particularly preferable. The compound has a tilt angle of its optical axis on the substrate side of the layer of 50 ° to 90 ° from the substrate normal direction, and
On the anti-substrate side, it continuously changes to be 0 ° to 60 °, and further, the azimuth angle of the optical axis is continuously twisted by about 45 ° or −45 ° from the substrate side of the layer toward the anti-substrate side. Or a compound having optically negative uniaxiality has an optic axis whose tilt angle is 5 ° to 50 ° from the substrate normal direction on the substrate side / anti-substrate side of the layer, In addition, the central portion of the layer continuously changes to be approximately 90 °, and the azimuth angle of the optical axis is continuously twisted by approximately 90 ° or approximately −90 ° from the substrate side of the layer toward the anti-substrate side. It is desirable to orient the film so that it changes. The optical compensator of the present invention having these orientations is used in a normally white mode liquid crystal display device including a twisted nematic liquid crystal cell having a twist angle of about 90 ° and two polarizing plates arranged on both sides of the cell. It is particularly effective for improving the viewing angle characteristics.

The transparent substrate used in the optical compensator comprising the transparent substrate of the present invention on which a layer containing a compound having negative uniaxiality is formed, has a small optical anisotropy and has a substantially optical axis. A resin film or the like in the normal direction can be used. Such films include cellulosic resins, polycarbonate, polysulfone,
Examples include solvent cast films of polyether sulfone and acrylic resin. Above all, a triacetyl cellulose film which is relatively inexpensive and has a small optical anisotropy and is uniform is preferably used. Here, the optical anisotropy of the transparent substrate means Δn′d = {(nx + ny) / 2, where nx and ny are the in-plane refractive indices, nz is the refractive index in the thickness direction, and d is the substrate thickness. In the optical compensator of the present invention, the inclination angle of the optical axis of the compound having optically negative uniaxiality represents the layer of the value of Δn′d represented by −nz} × d. Side is continuously changing from 50 ° to 90 ° from the substrate normal direction and 0 ° to 60 ° on the opposite substrate side, and the azimuth angle of the optical axis is further from the substrate side of the layer. Approximately 4 toward the non-board side
When producing an optical compensator that continuously changes so as to twist by 5 ° or approximately −45 °, the value of Δn′d is 4
It is preferable to use a substrate having a thickness of 0 nm or more. On the contrary, the direction of the optical axis of the compound having optically negative uniaxiality is different between the substrate side / anti-substrate side of the layer and the central part of the layer, and the inclination angle of the optical axis is the substrate side / anti-substrate side of the layer. On the side of the substrate is 5 ° to 50 ° from the normal direction of the substrate, and at the center of the layer, it is continuously changing so as to be about 90 °. When manufacturing an optical compensation plate that continuously changes so as to be twisted by approximately 90 ° or −90 ° toward the side, it is preferable to use a substrate having a value of Δn′d of 30 nm or less. Furthermore, an alignment treatment layer or an adhesion-imparting layer for obtaining a desired orientation can be formed on the surface of these films, if necessary.

The method for forming a layer containing a compound having negative uniaxiality on a transparent substrate is not particularly limited, and a normal method such as a direct gravure coater, a reverse gravure coater, a die coater, a comma coater may be used. However, from the viewpoint of the uniformity of the layer thickness, a method using a precision coat lip coater that does not use a backup roll is preferable.

The optical compensator of the present invention has a twist angle of about 90.
In order to effectively improve the viewing angle characteristics in a normally white mode liquid crystal display device including a twisted nematic liquid crystal cell of ° and two polarizing plates arranged on both sides of this cell, in order to effectively improve the viewing angle characteristics, When one sheet is used between the polarizing plates on both sides, the compound having optically negative uniaxiality has an inclination angle of its optical axis on the substrate side of the layer of 50 ° to 90 ° from the substrate normal direction. And continuously changes so as to be 0 ° to 60 ° on the anti-substrate side, and the azimuth angle of the optical axis is approximately 45 ° or approximately −45 ° from the substrate side of the layer toward the anti-substrate side. It is desirable to use an optical compensator having layers oriented such that it twists and changes continuously. When one optical compensator of the present invention is used between the liquid crystal cell and the polarizing plate on either side, a compound having an optically negative uniaxiality has a layer whose optic axis has a tilt angle. On the substrate side / opposite substrate side, the angle changes continuously from 5 ° to 50 ° from the substrate normal direction and about 90 ° in the center of the layer, and the azimuth angle of the optical axis is further changed from the substrate side of the layer. Approximately 90 ° or approximately -90 toward the non-substrate side
It is desirable to use an optical compensator having layers oriented so that it twists and continuously changes.

[0019]

By applying the optical compensator of the present invention,
The effect of remarkably improving the viewing angle characteristics of the M-TN-LCD can be obtained.

[0020]

【Example】

Example 1 FIG. 2 shows an alignment structure of optical axes of a compound layer having an optically negative uniaxial property in the optical compensation plate of this example. In this optical compensator, the layer of the compound having optically negative uniaxiality has an inclination angle of its optical axis of 85 ° from the substrate normal direction on the substrate side of the layer, and 0 on the anti-substrate side. The orientation is such that the azimuth angle of the optical axis continuously changes so as to be twisted by 45 ° from the substrate side of the layer toward the anti-substrate side.
This optical compensator is used in a normally white mode liquid crystal display device composed of a twisted nematic liquid crystal cell having a twist angle of 90 ° and two polarizing plates arranged on both sides of this cell. By using one each in the arrangement shown in FIG. 4 between the polarizing plate,
The viewing angle characteristics of this liquid crystal display device are significantly improved.

Example 2 FIG. 3 shows an alignment structure of optical axes of a compound layer having an optically negative uniaxial property in the optical compensation plate of this example. In this optical compensator, the layer of the compound having optically negative uniaxiality has an inclination angle of its optical axis on the substrate side and the non-substrate side of the layer of 5 ° from the substrate normal direction, and In the central portion, the orientation is continuously changed to be 90 °, and further, the orientation is such that the azimuth angle of the optical axis is continuously changed so as to be twisted by −90 ° from the substrate side of the layer toward the anti-substrate side. It was done. This optical compensator has a twist angle of 90.
In a normally white mode liquid crystal display device comprising a twisted nematic liquid crystal cell of ° and two polarizing plates arranged on both sides of the cell, a liquid crystal cell and a polarizing plate above the cell are shown in FIG. By using in the arrangement,
The viewing angle characteristics of this liquid crystal display device are significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an inclination angle and an azimuth angle of an optical axis of a compound having an optically negative uniaxial property in an optical compensation plate of the present invention.

FIG. 2 is a diagram showing an alignment structure of optical axes of a compound layer having an optically negative uniaxial property in the optical compensation plate of Example 1 of the present invention.

FIG. 3 is a diagram showing an alignment structure of optical axes of a compound layer having an optically negative uniaxial property in the optical compensation plate of Example 1 of the present invention.

FIG. 4 is a diagram showing setting of absorption axes of upper and lower polarizing plates, a labyrinth direction of a liquid crystal cell, and an alignment structure of an optical axis of an optical compensation plate in a liquid crystal display device using the optical compensation plate of Example 1 of the present invention. Is.

FIG. 5 is a diagram showing setting of absorption axes of upper and lower polarizing plates, a labyrinth direction of a liquid crystal cell, and an alignment structure of an optical axis of an optical compensation plate in a liquid crystal display device using the optical compensation plate of Example 2 of the present invention. Is.

[Explanation of symbols]

1 Optical axis direction of compound having negative uniaxiality 2 Azimuth angle 0 ° direction 3 Azimuth angle 90 ° direction 4 Azimuth angle 180 ° direction 5 Azimuth angle 270 ° direction 6 Orthographic projection direction of optical axis on substrate surface 7 Optics Azimuth angle of axis 8 Normal direction of substrate 9 Inclination angle of optical axis 41,51 Polarizer 42 above liquid crystal cell 42,52 Optical compensator 43 above liquid crystal cell 43,53 AM-TN liquid crystal cell 44 Optical below liquid crystal cell Compensation plate 45, 54 Liquid crystal cell lower polarizing plate 46, 56 Backlight 411, 511 Liquid crystal cell upper polarizing plate absorption axis direction 421, 522 Liquid crystal cell substrate optical axis direction in upper optical compensation plate 422, 521 Liquid crystal cell Opposite substrate optical axis direction in upper optical compensation plate 431, 531 Liquid crystal cell upper rubbing direction 432, 532 Liquid crystal cell lower rubbing direction 441 Liquid crystal cell lower optical compensation plate anti-substrate side optical axis direction 442 Liquid crystal cell lower side On the substrate side of the optical compensator The absorption axis direction of the academic axis 451, 541 liquid crystal cell lower side polarizing plate

[Procedure amendment]

[Submission date] April 18, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

Further, in order to obtain a thickness distribution such that both the azimuth angle of the optical axis and the inclination angle from the substrate normal direction, which are necessary for the present invention, continuously change in the thickness direction of the substrate, a disk is used. As the organic compound having a linear molecular structure, it is desirable to use an organic compound having a substituent having an optically active property that exhibits twist orientation in itself. Examples of the organic compound having a discotic molecular structure and a substituent exhibiting optical activity include C.I. Report of Destrade et al., PHYSICS LETTERS 79, 189
(+) Or (-)-2,3,6, described on the page
7,10,11-hexa- (2-methyloctylcarbo
Xy) triphenylene , (+) or (-)-2,
3,7,8,12,13-hexa- (2-methyloctyl
Lecarboxy) Turkusen , and J. Malthe
te et al., Mol. Cryst. Liq. Cr
yst. 64, 233, (+)-2,
3,6,7,10,11-hexa (S- (4-methyl)
Examples include discotic liquid crystals having an optically active group, such as -4-n-hexyloxybenzoyloxy) triphenylene.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

Further, as another method of exhibiting the twist orientation, an organic compound having a discotic molecular structure and exhibiting liquid crystallinity is used, which has a discotic molecular structure and does not exhibit liquid crystallinity and exhibits optical activity. Twist orientation can also be imparted by using together with an organic compound having a substituent. Examples of the organic compound having a discotic molecular structure, exhibiting no liquid crystallinity, and having an optically active substituent include C.I. Dest
Research report by Rade et al., PHYSICS LETTER
S (Vol. 79), page 189 (+) or
(-)-2,3,6,7,10,11-hexa- (2-
Methyloctylcarboxy) benzene etc. can be mentioned.

Claims (11)

[Claims] 1. A transparent substrate on which a layer containing a compound having optically negative uniaxiality is formed, and the azimuth angle of the optical axis of the compound and the inclination angle from the substrate normal direction are both the substrate. An optical compensator characterized by continuously changing in the thickness direction of the. 2. The direction of the optical axis of the compound having optically negative uniaxiality is different on the substrate side of the layer, on the side opposite to the substrate and on the central part of the layer, and the inclination angle of the optical axis is different on the substrate side of the layer. The angle is continuously changed from 50 ° to 90 ° from the substrate normal direction and from 0 ° to 60 ° on the anti-substrate side, and the azimuth angle of the optical axis is further changed from the substrate side of the layer to the anti-substrate side. The optical compensation plate according to claim 1, wherein the optical compensation plate is continuously changed so as to be twisted by about 45 ° or about −45 ° toward the side. 3. The direction of the optical axis of the compound having optically negative uniaxiality is different on the substrate side of the layer, on the side opposite to the substrate and on the central part of the layer, and the inclination angle of the optical axis is on the substrate side of the layer and On the side opposite to the substrate, it continuously changes from 5 ° to 50 ° from the substrate normal direction, and at about 90 ° in the central portion of the layer, the azimuth angle of the optical axis is further changed from the substrate side of the layer. The optical compensation plate according to claim 1, wherein the optical compensation plate is continuously changed so as to be twisted by approximately 90 ° or approximately -90 ° toward the side opposite to the substrate. 4. The compound according to claim 1, wherein the optically negative uniaxial compound is an organic compound having a discotic molecular structure and exhibiting liquid crystallinity. Optical compensator. 5. A compound having optically negative uniaxiality is an organic compound having a discotic molecular structure and exhibiting liquid crystallinity,
The optical compensator according to claim 4, wherein the discotic compound is used in combination with a chiral dopant. 6. A compound having optically negative uniaxiality is an organic compound having a discotic molecular structure and exhibiting liquid crystallinity,
5. The optical compensator according to claim 4, wherein the discotic compound is used in combination with an organic compound having a discotic molecular structure, exhibiting no liquid crystallinity and having an optically active substituent. . 7. The optically negative uniaxial compound is an organic compound having a discotic molecular structure exhibiting liquid crystallinity, and the discotic compound has a substituent having optical activity. The optical compensation plate according to claim 4. 8. The compound having an optically negative uniaxial property is an organic compound which does not exhibit liquid crystallinity and is oriented so as to exhibit a negative refractive index anisotropy by an electric field or a magnetic field. The optical compensator according to claim 1, claim 2 or claim 3. 9. A twisted nematic liquid crystal display device using at least one optical compensation plate according to claim 1. 10. The normally white mode liquid crystal display device comprising a twisted nematic type liquid crystal cell having a twist angle of about 90 ° and two polarizing plates arranged on both sides of the cell, wherein the optical compensation according to claim 2. A liquid crystal display device, wherein one plate is used between the cell and the polarizing plates on both sides. 11. A normally white mode liquid crystal display device comprising a twisted nematic liquid crystal cell having a twist angle of about 90 ° and two polarizing plates disposed on both sides of the cell, wherein the optical compensation according to claim 3. A liquid crystal display device, wherein one plate is used between the cell and one of the polarizing plates.