JPH02167527A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To allow perfect white and black display by providing a liquid crystal cell which crimps a nematic liquid crystal twist-oriented to >=120 deg. between a pair of substrates formed with electrodes on the inside surfaces facing each other and a liquid crystalline high-polymer film which is an optically anisotropic body between a pair of polarizing plates. CONSTITUTION:The liquid crystal cell 12 is constituted by forming the transparent electrodes 14 on the substrates 13 and further, forming oriented films 15 thereon and subjecting the films to a rubbing treatment. The upper and lower substrates are dis posed to face each other via a spacer 16 to constitute the structure holding the liquid crystal 17 in place. The liquid crystalline high-polymer film 19 which is at least one layer of the optically anisotropic body is provided between a pair of the polarizing plates 11 and 18. The incident light on one polarizing plate 11 is polarized to the elliptically polarized light varying in the major axis direction at each of respective wavelengths between the liquid crystal cell 12 and the liquid crystalline high-polymer film 19 adjacent to the liquid crystal 12 and thereafter, this light is made into the elliptically polarized light having the unified major axis direction at each of the respec tive wavelengths at the time when this light is made incident on the other polarizing plate 18. The white and black display is enabled in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal device, particularly a super twisted nematic type liquid crystal device.

[Conventional technology] Conventional super twisted nematic type (hereinafter referred to as ST
As disclosed in Japanese Patent Application Laid-Open No. 6050511, an N-type liquid crystal device has a twist angle of liquid crystal molecules of 90 degrees or more, and a pair of polarizing plates are provided above and below the liquid crystal cell, and these polarization axes (
The included angle between the absorption axis) and the molecular axis direction of the liquid crystal molecules adjacent to the electrode substrate was in the range of 30 degrees to 60 degrees. Therefore, due to the coloring caused by birefringence, the external hue of the liquid crystal cell when no voltage is applied is not white, but generally has a hue ranging from green to yellowish red.

Further, the external hue when a selection voltage is applied is generally blue instead of black.

FIG. 17 is a schematic diagram of a conventional STN type liquid crystal device. In the figure, 171 is an upper polarizing plate, 172 is a liquid crystal cell, a transparent electrode 174 such as an IT○ electrode is formed on a substrate 173, and an alignment film 175 is further applied and rubbed. The upper and lower substrates face each other with a spacer 176 in between, and have a structure in which a liquid crystal 177 is sandwiched between them. 17
8 is a lower polarizing plate.

FIG. 19 is an explanatory diagram showing the relationship between the liquid crystal cell and the polarization axis (absorption axis) of the polarizing plate in the above-mentioned liquid crystal device. Rubbing direction of lower electrode substrate of cell, 1
92 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, 193 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 194 is the helix angle of the liquid crystal molecules of the liquid crystal cell, and 195 is the upper electrode The angle 196 is between the rubbing direction 190 of the substrate and the direction 192 of the polarization axis (absorption axis) of the upper polarizing plate, and the angle 196 is between the rubbing direction 191 of the lower electrode substrate and the direction 193 of the polarization axis (absorption axis) of the lower polarizing plate. represents the angle formed by

In Fig. 19 above, angle 194 is 200 degrees, angle 1
95 is approximately 50 degrees each, and the refractive index anisotropy Δ of the liquid crystal is
The product Δn·d of n and the thickness d of the liquid crystal layer is 0. FIG. 20 shows the optical characteristics of the liquid crystal device when the thickness is 9 μm.

The figure shows a pixel in the positive mode (bright when no electrolyte is applied) and an off-state pixel when the liquid crystal device is driven by the multiplex driving method that is commonly used for driving this type of liquid crystal device. It shows the spectrum of the light transmittance of the pixel in the state.

Note that the OFF state refers to a state in which no electric field is applied, or even when an electric field is applied, the molecular orientation in the non-applied state is maintained, and the ON state refers to a state in which the molecular orientation of the liquid crystal changes optically. It refers to a state that is necessary and sufficient to bring about change.

In Fig. 20 above, the curve T shows the spectrum of the pixel in the OFF state, the cube ■ shows the spectrum of the pixel in the ON state, and the curve I shows the spectrum of the pixel in the OFF state.
It can be seen that the ``bright'' curve ``■'' is the ``dark 1'', that is, the curves I and ■ can be visually distinguished.

[Problem to be solved by the invention]

However, when the spectrum shown in Fig. 20 above is plotted on color coordinates, it becomes as shown in Fig. 21, which shows that in the conventional liquid crystal device, in positive mode, the color is yellow in the off state and blue in the on state. I understand.

As described above, in the conventional technology, when in the positive mode, the external appearance of the liquid crystal device in the off state is colored green, yellow-green, yellow, or yellow-red, and furthermore, in the on state, it becomes blue or dark blue. Also, when in negative mode (dark when no voltage is applied), the color is dark blue in the off state, and yellow in the on state.

These colors are not colors that are generally preferred as display colors for liquid crystal devices. After all, the display color of a liquid crystal device is a combination of white and black, that is, if it is expressed as a spectrum,
A combination of flat spectra is psychologically and physically most suitable, and there is a need for a liquid crystal device that can display black and white. In particular, when color display is performed in combination with a color filter, whether or not the spectrum is flat has a great effect on the vividness of the color. Aside from green, it becomes difficult to display blue and red with high brightness.

By the way, as a means to eliminate the above-mentioned coloring, in a Leistend nematic type (hereinafter referred to as TN type) liquid crystal device, a twisted nematic which does not have a power supply means in a single layer type Leistened nematic field effect liquid crystal display cell is used. A liquid crystal device having a two-layer structure in which liquid crystal layers are superimposed is known (see, for example, Japanese Patent Laid-Open No. 57-96315).

However, the liquid crystal device disclosed in the above publication cannot be directly applied to the STN type liquid crystal device described above.

That is, the liquid crystal device described in the above publication is of the so-called TN type. That is, the helix angle is 90 degrees, the polarizing plate is arranged parallel or perpendicular to the direction of adjacent liquid crystal molecules, and its operating principle is based on optical rotation. Therefore, the structure is significantly different from the STN type liquid crystal device, which actively utilizes birefringence as an operating principle, and therefore cannot be simply applied to an STN type liquid crystal device as is.

The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a liquid crystal device capable of black-and-white display, and furthermore, to provide a liquid crystal device suitable for color display.

[Means to solve the problem]

The liquid crystal device of the present invention comprises a liquid crystal cell in which a nematic liquid crystal twisted at an angle of 120° or more is sandwiched between a pair of substrates having electrodes formed on their opposing inner surfaces, and at least one layer of an optically anisotropic material. a liquid crystalline polymer film between a pair of polarizing plates, and the light incident on one polarizing plate is
Between the liquid crystal cell and the liquid crystalline polymer film adjacent to the liquid crystal cell, each wavelength becomes elliptically polarized light with a different major axis direction, and then when it enters the other polarizing plate, the major axis direction is different for each wavelength. The above-mentioned problem is solved by arranging the liquid crystalline polymer film so that the directions of the elliptically polarized light are almost uniform.

A typical example of a liquid crystal device according to the present invention is shown in FIG.

In the figure, 11 and 18 are linear polarizing plates, 12 is a display liquid crystal cell, and 19 is an optically anisotropic body.

The liquid crystal cell 12 has a structure in which a transparent electrode 14 is formed on a substrate 13, and an alignment film 15 is further formed and rubbed. The upper and lower substrates face each other with a spacer 16 in between, and have a structure in which a liquid crystal 17 is sandwiched between them.

The polarizing plate, liquid crystal material, liquid crystal alignment method, liquid crystal element driving method, etc. used in the present invention are conventional TN type or STN type.
The same one that is generally known for type liquid crystal devices and the like can be applied.

The details will be explained below.

The optical properties are greatly influenced by the polarization properties of the polarizing plate used. Although LLCI-8218 manufactured by Royal Electric Co., Ltd. is used in all specific examples of the present invention to be described later, it goes without saying that the invention is not limited to this. FIG. 15 shows the wavelength dependence of the light transmittance of the two polarizing plates. In the figure, ■ is a spectrum curve when a pair of polarizing plates are arranged parallel to each other, and ■ is a spectrum curve when a pair of polarizing plates are arranged perpendicular to each other.

The liquid crystal composition used in the present invention is a nematic liquid crystal with positive dielectric anisotropy. An example of a preferable liquid crystal is 5S-4008 manufactured by Chisso Corporation. Examples of other preferred liquid crystal compositions include those shown below.

CzHg ThcN CAH9 ThcN 14% 16% CJH1+3C21-+6 5% It is preferable to add a chiral dopant to the liquid crystal composition in order to keep the twisting structure of the liquid crystal stable.

Examples of chiral dopants include CB15 manufactured by BDH Co., Ltd. to create a right-handed helical structure, and S-81 manufactured by Merck & Co., Ltd. to create a left-handed helical structure.
1 can be used.

The structure of the liquid crystal cell 12 used in the present invention can be exactly the same as the liquid crystal cell 172 used in the prior art shown in FIG. 17.

In FIG. 1, a transparent substrate such as glass or plastic is used as the substrate 13. For example, on the board there is an IT
A transparent electrode 14 such as O and an alignment film layer 15 for determining the alignment of liquid crystal are formed on the transparent electrode.

Preferred examples of materials used as the alignment film layer include polyimide and polyvinyl alcohol.

Generally, by rubbing these alignment film layers, a certain alignment can be given to the liquid crystal. Further, as another liquid crystal orientation method, an oblique evaporation method such as St○ can also be used.

An example of the method for driving the liquid crystal device of the present invention is shown in FIG. Although the multiplex driving method shown in the figure is currently commonly used and has been put into practical use, other driving methods can also be used in the present invention.

As the optically anisotropic body 19 used in the present invention, for example, a liquid crystal composition, a -axis stretched film, a liquid crystalline polymer film, a film made of a mixture of liquid crystal and a polymer compound, etc. are used. When using a liquid crystal composition, smectic liquid crystal, cholesteric liquid crystal, nematic liquid crystal, etc. can be used. Specifically, it is a desirable method to use nematic liquid crystals, and moreover, to use nematic liquid crystals as well as display cells. - For the axially stretched film, for example, a film obtained by uniaxially stretching polyvinyl alcohol, polyester, polyetheramide, polyethylene, etc. can be used. As the liquid crystalline polymer film, for example, a polypeptide-polymexcrylate-1 mixed film can be used. In addition, other liquid crystalline polymers can be used in addition to polypeptides, but specifically, liquid crystalline polymers exhibiting a cholesteric phase are preferable. - As an example, the structural formula is shown below.

When using a film made of a mixture of liquid crystal and polymer as an optically anisotropic body, for example, )) CI system,
A liquid crystal composition in which a chiral dopant is mixed with a low-molecular liquid crystal such as CCH type or biphenyl to give it a helical structure is mixed with a polymer such as polymethylmeccryle-1, polyvinyl acetate, polyamide, etc. can be used. A preferred example of a liquid crystal composition mixed into a polymer is shown.

C2H6 < Wing 1 ON 16% CM9 I Wing CN 6% Self H11 ((Ice -CN 4% [Function]) The novelty of the present invention is that in order to prevent coloring in conventional STN type liquid crystal devices, The present invention is provided with an optically anisotropic body.The function played by this optically anisotropic body will be explained in detail below.

FIG. 18 is an explanatory diagram of the optical characteristics of the conventional STN liquid crystal device in the OFF state shown in FIG. 17, and in the figure, 181 is incident light. The person 1.1 light 181 is generally natural light, and includes light of all wavelengths in the visible region and has random polarization directions. The incident light 181 is transmitted to the linear polarizing plate 182.
When it passes through, linearly polarized light 1831/18 whose polarization direction is aligned
32, 1833, etc. Here 1831.18
32-1833 have wavelengths of 450nm and 550nm, respectively.
, 650 nm polarization. Naturally, linearly polarized light with other wavelengths is also included, but only these three wavelengths are shown here as representative wavelengths of the three colors of blue, green, and red. These linearly polarized lights 1831, 1832, and 1833 are then transferred to the liquid crystal cell 1.
Pass through 84. The liquid crystal layer in the liquid crystal cell has a structure in which nematic liquid crystal exhibiting optically uniaxial refractive index anisotropy is twisted. How the polarization state changes when the linearly polarized light 1831, 1832, 1833, etc. passes through a liquid crystal layer having such a structure can be predicted by a method described later. For example, in the case of the aforementioned conventional liquid crystal device whose spectrum is shown in FIG. 20, the polarization states are 1851, 1852, and 1853, respectively.

By passing through the liquid crystal layer in this way, wavelength dispersion occurs in the polarization state. These polarized lights 1851 and 1852
- 1853 finally passes through a linear polarizing plate 186. Of the polarized light of each wavelength, only the component corresponding to the direction of the linear polarizing plate 186 passes through.

For example, in the conventional liquid crystal device mentioned above whose spectra are shown in FIG. It can be seen from this that the amount of light with a wavelength of 550 nm is large, and the amounts of light with wavelengths of 450 nm and 650 nm are small.

I in FIG. 20 is a spectral representation of these results, and I in FIG. 21 is a plot of this on color coordinates. As described above, conventional STN liquid crystal devices have no choice but to be in a colored state due to wavelength dispersion due to birefringence.

Next, FIG. 2 shows an explanatory diagram of the optical characteristics of the liquid crystal device according to the present invention in the off state. A comparison between FIG. 18 and FIG. 2 shows that FIG. 2 differs from FIG. 18 in that an optically anisotropic body 28 is added as a component. For convenience of explanation,
The conditions of the components except for the optically anisotropic body 28 and the polarizing plate 26 are the same as the conventional example shown in FIG. 18 above, that is, the liquid crystal device shown in FIG. 20. Therefore, in FIG. 2, the polarization states 251, 252, and 25 of each wavelength after passing through the polarizing plate 22 and the liquid crystal cell 24 are as follows.
3 is exactly the same as 1851, 1852, and 1853 in FIG. The difference is that the polarized light 251, 252, 253 in FIG. 2 passes through the optically anisotropic body 28 next. In the present invention,
This optically anisotropic body 28 has polarized light 231, 232, 233
The optical anisotropic material has the effect of canceling the wavelength dispersion caused when the light passes through the liquid crystal cell 24.

In order to explain this effect in an easy-to-understand manner, the liquid crystal cell 24
Define the optical function of . Furthermore 231・232・2
If the polarization state of 33 is P, and the polarization states of 251, 252, and 253 are P'', then P'' can be obtained from P and M using the following equation.

P” −yl * p (1) Here, the optical function of the optical anisotropic body 28 is a function M that performs the inverse transformation of M.
-1. Letting the polarization state of 291, 292, and 293 be P''', P'' can be obtained from P' and M-' using the following equation.

P"-M-'*P" (2) The following equation can be found from equations (1) and (2).

P''=M-'*M*P (3) Obviously, M-' * M= 1 (4) Therefore, P'= P (5) Equation (5) is 29
The polarization states (P) of 1, 292, and 293 are 2, respectively.
It shows that the polarization state (P) is the same as that of 31, 232, and 233. 231, 232, 233 are natural light 21
Since this is the polarized light immediately after passing through the linear polarizing plate 22, all wavelengths are linearly polarized light having a vibration direction corresponding to the orientation of the polarizing plate 22. Therefore, 291, 292, 293 are also 23
It is linearly polarized light with a vibration direction in the same direction as 1, 232, and 233. The polarization axis direction of the linear polarizing plate 26 is the polarization 291
・If it matches the vibration direction of 292 and 293,
This linearly polarized light passes through the linear polarizing plate 26 as it is, and
It becomes 1・272・273.

The spectrum of the emitted light at this time matches the spectrum of the polarizing plate shown in FIG. The spectrum of the polarizer is fairly flat and colorless. In this manner, the liquid crystal device according to the present invention can eliminate the coloring phenomenon in the off state.

The main points of the present invention are as described above, but the problem is that, as shown in FIG. The question is whether anisotropic objects can actually exist. In conclusion, the present inventors have found that such conditions for the optically anisotropic body 28 may exist.

Moreover, it has been found that such conditions can exist regardless of the conditions of the liquid crystal cell 24.

To explain this condition, FIG. 3 shows the relationship among the liquid crystal cell, the polarizing plate, and the optical fishing tackle cube in the liquid crystal device of the present invention shown in FIG. 1. In the figure, 31 is the rubbing direction of the lower electrode substrate of the liquid crystal cell, 32 is the rubbing direction of the upper electrode substrate of the liquid crystal cell, 33 is the optical axis direction of the optically anisotropic surface facing the liquid crystal cell, and 34 is the rubbing direction of the upper electrode substrate of the liquid crystal cell. 35 is the direction of the polarization axis (absorption axis) of the lower polarization plate, 36 is the direction of the polarization axis (absorption axis) of the upper polarization plate, and 37 is the direction of the optical axis of the surface of the optically anisotropic body facing the polarization plate. The angle between the polarization axis direction 36 of the upper polarizing plate and the optical axis direction 34 of the optically anisotropic body, 38 is the angle between the optical axis directions 33 and 34 of the optically anisotropic body, and 39 is the angle between 33 and 32. The angle 40 is the helix angle of the liquid crystal layer in the liquid crystal cell, and 30 is the angle between the rubbing direction 31 of the liquid crystal cell and the direction 35 of the polarization axis of the lower polarizing plate.

Here, for example, the conditions of the liquid crystal cell are exactly the same as those of the conventional positive mode liquid crystal device whose spectrum is shown in FIG. The whitening conditions when d is 0.9 μm will be described. If there is no optically anisotropic material, the spectrum will naturally be as shown in FIG. 20, resulting in a colored state. However, when a liquid crystal cell, for example, is used as an optically anisotropic object, and the twist angle 38 of the liquid crystal layer is -200 degrees (that is, the twist angle is opposite to the display liquid crystal cell and the absolute value of the twist angle is equal), Δn-d is 0 degrees. When 9 μm is used, the spectrum in the off state becomes almost flat, as shown in FIG. However, the other conditions at this time are that 37 in Figure 3 is 45 degrees, and 30 is 45 degrees.
5 degrees and 39 are 90 degrees. FIG. 5 shows the spectrum shown in FIG. 4 plotted on color coordinates. Said second
It can be seen that the color is almost white compared to the conventional method shown in FIG. As shown in the above example, there exist conditions for the optically anisotropic body 28 to perform the inverse conversion of the liquid crystal cell 24 as shown in FIG. 2, regardless of the wavelength. This correspondence relationship is shown as follows. That is, (1) Δn-d of the liquid crystal cell and Δn of the optical anisotropic body
- The absolute values of d are equal.

(2) If the twist angle of the liquid crystal cell is θ, the twist angle of the optically anisotropic body is minus θ (the direction of twist is opposite).

(3) The angle 39 formed between the optical axis direction 33 of the surface of the optically anisotropic body facing the liquid crystal cell and the rubbing direction 32 of the upper electrode substrate of the liquid crystal cell is 90 degrees.

When the above three conditions are met, coloring in the off-state of the liquid crystal device can be completely eliminated, that is, whitening can be achieved, regardless of the value of Δn−d or the value of the twist angle θ.

All of the above explanations were about the mechanism of coloration elimination in the off state. In the present invention, coloring in the on state is also eliminated. Although it is not impossible to strictly explain the reason for the elimination of coloring in the on state, it is complicated. In any case, the inventor has experimentally confirmed that there is no (or almost no) coloration in the on state under various conditions, as shown in many examples in the Examples described below.

As mentioned above, in order to completely eliminate the coloring in the off state of the positive mode, it is necessary that the above three conditions are satisfied. However, in reality, it is often sufficient for practical use even if the optically anisotropic material does not necessarily provide a complete inverse transformation of the transformation of the liquid crystal cell as shown in FIG. This is conceptually shown in FIG. FIG. 6 corresponds to FIG. The difference from FIG. 2 is that the states 691, 692, and 693 of each polarized light after passing through the optically anisotropic body 68 are 291, 2, and 2 in FIG.
It is not completely linearly polarized light like 92.293, but slightly elliptically polarized light. As a result, the polarizing plate 66
After passing through the polarized lights 671, 672, and 673, the intensity has a slight wavelength dependence. for example,
The spectrum under the conditions shown in Example 20, which will be described later, is shown in FIG. 8, and the spectrum is plotted on color coordinates in FIG. 9. In the case of the conditions shown in Example 20, the state of polarization after passing through the optical anisotropic body is elliptically polarized, as shown at 691, 692, and 693 in FIG.

Nevertheless, as shown in FIG. 9, the coloring was almost completely eliminated. Incidentally, FIG. 7 shows the relationship among the axes of the optically anisotropic body, the liquid crystal cell, and the polarizing plate in this case.

In this way, even under conditions where the above three conditions are not satisfied, there exist conditions for an optically anisotropic material in which coloring can be sufficiently eliminated.

Alternatively, for other reasons, it may be more desirable to use an optically anisotropic material other than the above three conditions in a positive sense. One of the reasons for this is that the characteristics of polarizing plates are generally wavelength dependent. An example is shown in FIG. By appropriately selecting such wavelength characteristics and the conditions of the optically anisotropic body, the coloring of the liquid crystal device can be improved. This applies not only to the off state but also to the on state. Other reasons are
The conditions for the optically anisotropic body may be changed in consideration of the wide viewing angle.

Various conditions for the optically anisotropic body in the configuration shown in FIG. 1 have been described above. In the configuration shown in FIG. 1, the optically anisotropic body is located above the liquid crystal cell in the drawing. However, it is clear that this hierarchical relationship has nothing to do with the essence of the present invention. This also applies to the positional relationship between the liquid crystal cell and the optically anisotropic body in FIGS. 2 and 6.

FIG. 10 shows another example of the structure of the liquid crystal device of the present invention. The configuration in FIG. 10 differs from the configuration in FIG. 1 in that optically anisotropic bodies are present both above and below the liquid crystal cell. Even in such a configuration, it is possible to effectively eliminate coloring completely as shown in FIG. Naturally, it is also possible to eliminate almost complete coloring as shown in FIG.

The above explanation applies to the state where the transmittance is high in the off state, that is,
It was an explanation of positive mode. The on-state state with low transmittance, that is, the negative mode, will be explained next. If the orientation of the polarization axis of the polarizing plate 26 shown in FIG.
293 etc. cannot pass through the polarizing plate 26. Therefore, the spectrum of the transmitted light at this time is the first
This matches the spectrum of the polarizing plate in the crossed Nicol state shown in Figure 5H (however, light absorption in the liquid crystal cell, optically anisotropic body, etc. is ignored). This state is the darkest state that can be obtained using the polarizing plate shown in FIG.

In this way, in the present invention, by using an optically anisotropic material, the best possible flat spectral characteristics can be obtained even in the negative mode state. That is, in either case, coloring can be eliminated.

Note that the following explanation will be made regarding the positive mode.

Next, a specific method for calculating a change in the polarization state of light that has passed through an optically anisotropic object such as a liquid crystal cell will be outlined below.

Light incident on an optically anisotropic body is generally elliptically polarized light.

The reference plane trace of the elliptically polarized light now traveling in the Z-axis stop direction can be expressed as follows by a column vector with xy acid components.

Here, aX −ay is the amplitude of xyTv, min, ω
is the angular frequency, and ψ9 and ψ are the phase angles of the xy acid components.

However, in this case, the absolute phase of the wave does not matter, so
The polarization state was described using the normalized Jones hector of the following equation, in which the optical frequency and absolute phase terms in equation (6) were omitted, and the amplitude of each component was also standardized.

(δmiψ, -ψX) Now, the polarized light E in equation (7) changes its polarization state when it passes through the optical anisotropic body, becoming polarized light E''. is represented by a 2×2 Jones matrix.

For example, when this optically anisotropic body is a uniaxial linear retarder like a film-like polymer, the Jones matrix RΔ·0 can be expressed by the following equation.

Here, θ is the angle that the fast axis of the linear phase shifter makes with the X axis,
Δ indicates retardation. Note that the retardation Δ is calculated using Δn-d of the linear phase shifter and the wavelength λ of the light.
It is defined as 2πΔn−d/λ.

The polarization state of the light that has passed through this film-like polymer is determined by the Jones matrix R of equation (8) from the left side of the incident light hector E.
By applying Δ and θ, it can be obtained as shown in the following equation.

E = RΔ・oE If the optically anisotropic body is a stack of multiple film-like polymers, then from the left side of the incident light vector E, sequentially (8 ) can be obtained as shown in the following equation by applying the Jones matrix of the equation.

E=Rbn, On RΔn-1,0I+-1"" Rh
zl) 2RΔIθIE When the optically anisotropic body is a liquid crystal cell, the liquid crystal molecules are twisted and oriented, so the retarder is complicated. However, if the liquid crystal layer is divided into a sufficiently large number of layers as shown in FIG. 11(a),
It can be approximated by stacking liquid crystal layers that are not twisted as shown in b). The non-twist-oriented liquid crystal layer is a uniaxial linear retardator like the film-like polymer, so the light passing through the liquid crystal cell can be The polarization state of can be determined.

Using the method explained above, the angle 40 in FIG.
degree, angle 38 is minus 200 degrees, angle 30 is 45 degrees,
Calculated by dividing the liquid crystal layer into 20 parts each under the above conditions, where angle 37 is 45 degrees, angle 39 is 90 degrees, and Δn・d of the display liquid crystal cell and optical anisotropic body are both 0.9 μm. The transition of the polarization state of the light is shown in FIGS. 12 to 14. Figures 12, 13, and 14 are, respectively,
It shows the polarization state transition of light with wavelengths of 45 Onm, 55 Onm, and 65 Onm. For example, in the case of FIG. 12, the linearly polarized light 121 incident on the display liquid crystal cell in FIG.
The polarization state changes and the light is emitted from the cell as 125 elliptically polarized light. This elliptically polarized light 125 continues to be incident on the optically anisotropic body in FIG.
- The polarization state changes to 127 and 128, and the optically anisotropic body is emitted as linearly polarized light of 129. In each of the above processes, the conversion of the polarization state by the optical anisotropic body shown in Figure (b) is as follows:
This corresponds to exactly the inverse transformation of the conversion by the display liquid crystal cell shown in FIG. 3A, and therefore, the light incident on the display liquid crystal cell exits the optically anisotropic body in exactly the same polarization state. As is clear from FIGS. 13 and 14, this effect exists regardless of the wavelength of light, so in the liquid crystal display device configured according to the present invention, coloring in the off state is completely eliminated.
Whitening is possible.

Furthermore, as described above, there are conditions for an optically anisotropic material in which coloring can be sufficiently eliminated even if the above three conditions are not satisfied. The conditions are that light incident on one polarizing plate becomes elliptically polarized light with a different major axis direction for each wavelength between the liquid crystal cell and the optical anisotropic body adjacent to the liquid crystal cell, and then The optically anisotropic body may be arranged so that when the light is incident on the polarizing plate, the light becomes elliptically polarized with substantially the same major axis direction for each wavelength. Specifically, the conditions for the optically anisotropic body may be appropriately set according to the twist angle of the display liquid crystal cell and the value of Δn-d, and the conditions will be specifically explained below based on Examples.

〔Example〕

FIG. 22 is a cross-sectional view schematically showing the structure of a liquid crystal device of the present invention in which liquid crystal is used as an optically anisotropic body. In the figure, 2201 is an upper polarizing plate, 2202 is a liquid crystal cell (hereinafter referred to as A cell) in which liquid crystal as an optically anisotropic body is sandwiched between two substrates, 2203 is an upper substrate of A cell, and 2204 is A cell. lower substrate, 22
05 is a liquid crystal used as an optically anisotropic body, 2206 is a liquid crystal cell that performs display by applying voltage (hereinafter referred to as B cell)
, 2207 is the upper electrode substrate of the B cell, 2208 is the lower electrode substrate of the B cell, 2209 is the liquid crystal of the B cell, and 2210 is the lower polarizing plate.

FIG. 23 is a diagram showing the relationship between each axis of the liquid crystal device of the present invention. In the figure, 2311 is the rubbing direction of the lower electrode substrate of cell B, 2312 is the rubbing direction of the upper electrode substrate of cell B, 2313 is the rubbing direction of the lower substrate of cell A, and 2314 is the rubbing direction of the upper substrate of cell A. Rubbing direction, 2
315 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 231
6 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, 2317 is the angle between the direction 2316 of the polarization axis (absorption axis) of the upper polarizing plate and the rubbing direction 2314 of the upper substrate of the A cell, 23
18 is the size of the liquid crystal helix angle in the A cell, 2319 is Δ
Angle between the rubbing direction 2313 of the lower cell substrate and the rubbing direction 2312 of the upper electrode substrate of the B cell, 232
0 is the size of the helix angle of the liquid crystal in the B cell, 2321 is the B
This is the angle between the rubbing direction 2311 of the lower electrode substrate of the cell and the direction 2315 of the polarization axis (absorption axis) of the lower polarizing plate. Hereinafter, the twisting direction of the liquid crystal molecules in each cell will be indicated by the twisting direction from the top to the bottom of the cell.

[Example 1] In Fig. 23, the helix angle 2320 of the liquid crystal of cell B is about 200 degrees to the left, Δn-d is about 0°9 μm, the angle 2319 is about 90 degrees, and the angle 2317 is from 30 degrees. 60 degrees, and the angle 2321 is in the range from 30 degrees to 60 degrees, when the twist angle 238 and Δn-d of the liquid crystal of cell A are the shaded areas in Fig. 24(a), the off state The result is a liquid crystal device that becomes almost white in the on state and almost black in the on state.

The above conditions can be calculated by using equations (6) to (8) above, and an example of the calculation method will be described below.

That is, Δn-d = 0°9μm twisted 200' to the left
The liquid crystal of cell B is divided into 200 parts in the thickness direction of the cell, and 1
Calculations are performed using the above formula assuming that each layer has a structure in which a uniaxial retarder of Δn-d=0.0045 μm is twisted to the left by 1°. The wavelength of the light used at this time is in the range of 400 nm to 700 nm. In addition, the state of polarization of the light incident on the liquid crystal of the B cell differs depending on the type of polarizing plate used and the direction of the axis. 0%
) shall be used. The angle between the rubbing direction of the substrate adjacent to the polarizing plate (the direction of liquid crystal molecules on the substrate surface) and the direction of the polarization axis of the polarizing plate is 45°. Then, B
Linearly polarized light that has passed through the polarizing plate is incident on the cell, and the state of elliptically polarized light of each wavelength that has passed through the B cell is determined.

Next, the state of the elliptically polarized light after it enters and passes through the A cell is determined. The elliptically polarized light incident on the A cell is determined by the same calculation as above, and the angle formed by the rubbing direction of the adjacent substrates of the A cell and the B cell is 90 degrees. In addition, the liquid crystal of cell A is divided into 200 parts in the thickness direction of the cell, and the -axis retarder is twisted to the right by 0°7 degrees, resulting in a total of 14 parts to the right.
Assuming that the liquid crystal layer has a 0 degree twisted structure, Δn−
When d is set to an appropriate value, the state of the elliptically polarized light that has passed through the A cell can be determined from the above calculation formula. Furthermore, here, the angle between the rubbing direction of the substrate adjacent to the polarizing plate and the direction of the polarization axis of the polarizing plate is set to 45 degrees, and the spectrum after passing through the polarizing plate is determined, and the Y-direction with visibility correction is determined.

'' In the two-layer calculation, the value of Δn-d of the liquid crystal of cell A is set from 0 μm to 1.5 μm, and the relationship between Δn-d of cell A and the Y value corrected for visibility is determined.

At this time, when Δn-d of cell A is plotted on the horizontal axis and the Y value is plotted on the vertical axis, the Y value has a maximum value and a minimum value and changes periodically, as shown in FIG. 24(b). The angle between the polarization axis and the rubbing direction is 4
Since there are two directions in which the angle is 5 degrees, the above figure 24(b)
Two curves are drawn.

Display modes include negative mode (dark when no voltage is applied) and positive mode (bright when no voltage is applied). In negative mode, it is desirable that the state where no voltage is applied is darker, and in positive mode, it is desirable that the state where no voltage is applied is brighter. Therefore, in FIG. 24(b), the portion where the Y value is maximum is suitable for positive mode, and the portion where Y value is minimum is suitable for negative mode.

The Y value in the conventional negative mode voltage application state is as high as about 5% (and it can be seen that it is clearly colored blue both visually and on the color coordinates).

On the other hand, the minimum Y value in Fig. 24(b) is less than half of the negative mode Y (a) of the conventional STN liquid crystal device.The color at this time is slightly colored on the color coordinates. However, because the Y value is small, it is recognized as a color close to black when viewed visually. Also, when a voltage is applied, it is recognized as white. Therefore, in negative mode, a black and white display is obtained in the part where the Y value is minimum. At this time, Δn-d becomes the desired value.

The portion where the Y value is maximum becomes closer to white both visually and on the color coordinates when compared with the color in the conventional positive mode when no voltage is applied. However, the color is close to white even before and after the portion where the Y value is maximum. Therefore, in positive mode, the area where black and white display can be obtained is quite wide, and it is extremely difficult to determine the boundaries. Also, since the angle between the polarization axis and the rubbing direction is 45 degrees, if the direction of the polarization axis for one curve in FIG. 24(b) is shifted by 90 degrees, it will match the polarization axis for the other curve. Therefore, Figure 24 (
The values of Δn-d at the maximum and minimum in b) are the same.

From the above, black and white is the minimum Y value Δn−
It is d. In other words, when cell B is 200 degrees left-handed, Δn
-d = 0.9 μm, the rubbing direction of the substrate of the B cell adjacent to the polarizing plate and the direction of the polarization axis of the polarizing plate are 45 degrees, and each rubbing of the adjacent substrates of the B cell and the A cell is The angle between the two directions is 90 degrees, the A cell is right-handed at 140 degrees, and the angle between the rubbing direction of the substrate of the A cell adjacent to the polarizing plate and the direction of the polarization axis of the polarizing plate is 45 degrees.
degree, Δn-d of A cell is 0°33μm, 0
．． 7μm, 1.0am, 1. ．． 3ttm (Δn of A cell
-d is 1.5 μm or less), a black and white display is obtained (see FIG. 24(b)).

Next, if the rubbing direction of the substrate of each cell adjacent to the polarizing plate and the direction of the polarization axis of the polarizing plate are other than 45 degrees, or the angle formed by the rubbing direction of each adjacent substrate of B cell and A cell is 90 degrees. The same procedure is used for calculations other than degrees. Then, Δn-d of cell A, where the Y value is minimum, is
It is found as a range that appears periodically with a certain width (24th
Distribution of Δn-d when the helix angle is fixed at 140 degrees to the right in Figure (a)). However, the angle formed by the direction of each axis at this time is within a range where the minimum value of the Y value is 3% or less, or where extreme coloring does not occur.

In addition, even when the conditions for B cell remain the same and only the size of the torsion angle of A cell is changed, the range of Δn-d of A cell where the Y value becomes minimum is periodic, similar to the two-layer case. It will appear. Figure 24 (a) summarizes the relationship between the torsion angle of cell A and △n-d determined in this way.
becomes. In other words, from FIG. 24(a), cell B is 200
When Δn-d is 0.9 μm for left-handed twisting of degrees, there is not only one condition for the size of the helix angle and Δn-d of the A cell that provides a black and white display, but a certain fan-shaped range has a periodicity. It can be seen that it exists.

Further, even when the helix angle and Δn-d of the B cell are changed, the helix angle and Δn·d of the A cell that provide a black-and-white display can be determined by the same procedure as described above. In this case as well, the relationship between the helix angle of the A cell and Δn·d is fan-shaped and appears periodically.

In this way, for any given B cell torsion angle and Δn・d, the A cell torsion angle and Δn− for black and white display are determined.
d can be determined, and the torsion angle of the A cell and Δn−
There is not only one d, but many.

[Example 2] In Example 1, the angle 2317 in FIG. 23 is approximately 40 degrees, the helix angle 2318 of the liquid crystal of cell A is approximately 140 degrees to the right, the angle 2319 is approximately 90 degrees, and the liquid crystal of cell B is The twist angle 2320 is about 200 degrees left-handed, the angle 2321 is about 40 degrees, Δn-d of the liquid crystal layer of cell A is about 0.7 μm, and B
The Δn-d of the liquid crystal layer of the cell is approximately 0.9 μm. FIG. 25 shows the spectrum of the appearance of the liquid crystal device at this time. In the figure, a curve I indicates an off state, and a curve ■ indicates an on state. The external appearance spectrum of the conventional liquid crystal device shown in FIG. 20 is yellow when off (curve I) and blue when on (curve ■). However, as shown in FIG. 25 above, in the liquid crystal device of the present invention, the color is almost white in the off state, and the color is almost black in the on state.

[Example 3] In Example 1, the angle 2317 in FIG. 23 is approximately 40 degrees, the helix angle 2318 of the liquid crystal of cell A is approximately 200 degrees right-handed, the angle 2319 is approximately 90 degrees, and the liquid crystal of cell B is The torsion angle 2320 is approximately 200 degrees to the left, the angle 2321 is approximately 50 degrees, Δn-d of the liquid crystal layer of cell A is approximately 0.9 μm, and B
The Δn-d of the liquid crystal layer of the cell is approximately Q, 971 m. The spectrum of the appearance of the liquid crystal device at this time is shown in FIG.

In the figure, a curve (■) indicates an off state, and a curve (2) indicates an on state. In this case as well, as in Example 2, the color is almost white in the off state and almost black in the on state.

[Example 4] In Example 1, the angle 2317 in FIG. 23 is approximately 40 degrees, the helix angle 2318 of the liquid crystal of cell A is approximately 260 degrees right-handed, the angle 2319 is approximately 90 degrees, and the liquid crystal of cell B is The twist angle 2320 is about 200 degrees to the left, the angle 2321 is about 40 degrees, and the Δn-d of the liquid crystal layer of the A cell is about 0. 8μm,
The Δn-d of the liquid crystal layer of the B cell is approximately 0.9 μm. The spectrum of the appearance of the liquid crystal device at this time is shown in FIG.

In the figure, a curve (■) indicates an off state, and a curve (2) indicates an on state. In this case as well, as in Examples 2 and 3, the color is almost white in the off state and almost black in the on state.

[Example 5] In FIG. 23, the helix angle 2320 of the liquid crystal of cell B is about 250 degrees to the left, Δn-d is about 0°9 μm, the angle 2319 is about 90 degrees, and the angle 2317 is from 30 degrees. 60 degrees, and the angle 2321 is in the range from 30 degrees to 60 degrees, when the torsion angle 2318 and Δn-d of the liquid crystal of cell A are the shaded areas in Fig. 28, the color becomes almost white in the off state. , a liquid crystal device that is almost black in the on state can be obtained.

[Example 6] In Example 5, the angle 2317 in FIG. 23 is approximately 40 degrees, the helix angle 2318 of the liquid crystal of cell A is approximately 160 degrees right-handed, the angle 2319 is approximately 90 degrees, and the liquid crystal of cell B is The torsion angle 2320 is approximately 250 degrees to the left, the angle 2321 is approximately 40 degrees, Δn-d of the liquid crystal layer of cell A is approximately 0.8 μm, and B
The Δn-d of the liquid crystal layer of the cell is approximately 0.9 μm. The spectrum of the appearance of the liquid crystal device at this time is shown in FIG. In the figure, a curve I indicates an off state, and a curve ■ indicates an on state. In this case as well, as in Example 2, the color is almost white in the off state and almost black in the on state.

[Example 7] In FIG. 23, the angle 2317 is approximately 40 degrees, the helix angle 2318 of the liquid crystal in cell A is approximately 360 degrees to the right, the angle 2319 is approximately 90 degrees, and the helix angle of the liquid crystal in cell B 2320
is about 250 degrees to the left, the angle 2321 is about 40 degrees, and Δn-d of the liquid crystal layer of cell A is about 1. 0μm,
, Δn-d of the liquid crystal layer of cell B is approximately 0.9 μm. In this case as well, the liquid crystal device becomes white in the off state and blacker in the on state.

[Example 8] In FIG. 23, the angle 2317 is about 50 degrees, the helix angle 2318 of the liquid crystal in cell A is about 170 degrees right-handed, the angle 2319 is about 90 degrees, and the helix angle 2320 of the liquid crystal in cell B
is about 170 degrees to the left, the angle 2321 is about 40 degrees, and furthermore, Δn-d of the liquid crystal layer of cell A is about 0.7 μm, and B
The Δn-d of the liquid crystal layer of the cell is approximately 0.7 μm. At this time as well, the liquid crystal device becomes white in the off state, and becomes blacker in the on state.

[Example 9] In FIG. 23, the helix angle 2320 of the liquid crystal of cell B is about 120 degrees to the left, Δn-d is about 0°9 μm, the angle 2319 is about 90 degrees, and the angle 2317 is from 30 degrees. 60 degrees, and the angle 2321 is in the range from 30 degrees to 60 degrees, when the torsion angle 2318 and Δn-d of the liquid crystal of the A cell are the shaded areas in FIG. 30, the color becomes almost white in the off state, A liquid crystal device that is almost black in the on state is obtained.

(Example 10) In FIG. 23, the helix angle 2320 of the liquid crystal of cell B is about 200 degrees to the left, Δn-d is about 0°6 μm, the angle 2319 is about 90 degrees, and the angle 2317 is from 30 degrees. 60 degrees, and the angle 2321 is in the range from 30 degrees to 60 degrees, when the twist angle 2318 and Δn-d of the liquid crystal of the A cell are the shaded areas in Fig. 31, the color is almost white in the off state, and the color is almost white in the on state. A liquid crystal device that is almost black in color can be obtained.

[Example 11] In Fig. 23, the helix angle 2320 of the liquid crystal of cell B is approximately 200 degrees to the left, △n-d is approximately 1°5 μm, the angle 2319 is approximately 90 degrees, and the angle 2317 is 30 degrees. to 60 degrees, and the angle 2321 is in the range from 30 degrees to 60 degrees, when the twist angle 231B and Δn-d of the liquid crystal of cell A are the shaded areas in FIG. 32, the color becomes almost white in the off state, A liquid crystal device that is almost black in the on state is obtained.

[Example 12] In Fig. 23, the torsion angle 2320 of the liquid crystal of cell B is twisted to the left by about 350 degrees, Δn-d is about 019 μm, the angle 2319 is about 90 degrees, and the angle 2317 is from 30 degrees to 60 degrees. , if the angle 2321 is in the range from 30 degrees to 60 degrees, and the torsion angle 2318 and Δn-d of the liquid crystal of cell A are the shaded areas in FIG. A liquid crystal device with an almost black color can be obtained.

[Example 13] In Examples 1 to 12, the same effect can be obtained even if the A cell and the B cell are arranged upside down.

Further, the same effect can be obtained by replacing the two substrates, the lower substrate 2204 of cell A and the upper electrode substrate 2207 of cell B, shown in FIG. 22, with one substrate.

[Example 14] In FIG. 34, 3422 is an upper polarizing plate, 3423 is an upper A cell, 3424 is a B cell, 3425 is a lower A cell,
3426 is a lower polarizing plate. In the liquid crystal device having the structure shown in the figure, the liquid crystal molecules in both the upper A cell 3423 and the lower A cell 3425 are right-handed. Further, the liquid crystal molecules of the B cell 3424 are left-handed. At this time, the upper A cell 342
The sum of the torsion angle of the liquid crystal molecules in No. 3 and the torsion angle of the liquid crystal molecules in the lower A cell 3425 is the torsion angle of the entire A cell, and △n-d of the liquid crystal layer of the upper A cell 3423 and the torsion angle of the lower A cell The sum of Δn-d of the liquid crystal layer of cell 3425 is assumed to be Δn-d of the entire A cell. Even when the torsion angle of the entire human cell and Δn-d of the entire A cell are set to the conditions of the A cell of Examples 1 to 12, the same effects as those of Examples 1 to 12 can be obtained. Each of the above cells 3423 and 3424
- The same effect can be obtained by arbitrarily changing the arrangement order of 3425. Moreover, the A cell can also be provided in three or more layers under the same conditions as above.

[Example 15] In the structure of Example 14, the lower substrate 3429 of the upper A cell 3423 and the upper electrode substrate 3430 of the B cell 3424
2 boards are replaced with one board. Furthermore, the lower electrode substrate 3432 of the B cell 3424 and the lower A cell 3425
The two substrates of the upper substrate 3433 are replaced with one substrate. In this way, the number of substrates is reduced and the structure is simplified, and the same effects as in the fourteenth embodiment can be obtained.

[Example 16] In Examples 1 to 15, the temperature at point N1 of the liquid crystal in cell A is TA (K), and the temperature at point N1 of the liquid crystal in cell B is T.
Let it be B(K). At this time, 0.86≦TA/TB≦1
．． 15, the external color of the liquid crystal device hardly changes even if Δn-d of the liquid crystal layers of the B cell and the A cell changes due to a temperature change.

[Example L7] In Examples 1 to 16, when a liquid crystal with a positive dielectric anisotropy Δε is used as the liquid crystal in the A cell, the alignment of the liquid crystal in the A cell is disturbed due to the influence of external static electricity. Color unevenness may appear on the appearance of the liquid crystal device. Therefore, if a liquid crystal having a negative dielectric anisotropy Δε is used as the liquid crystal of the A cell, a liquid crystal device that does not have color unevenness in appearance even if it is influenced by static electricity from the outside can be obtained.

[Example 18] In Examples 1 to 16, an electrode is attached to the inside of the lower substrate of the A cell, and a liquid crystal having a positive Δε is used as the liquid crystal of the A cell. By doing so, even if the external color of the liquid crystal device changes due to a change in temperature, the change in color can be canceled out by applying a voltage between the electrodes attached to the upper and lower substrates of the A cell.

[Example 19] Excluding Example 13 and Example 15 <Example 1 to Example 18
In the steps up to this point, the A cell and the B cell are optically bonded to each other in order to prevent light from being reflected on the substrate surface where the A cell and the B cell are in contact. An embossed polyvinyl butyral film is used as an adhesive layer and bonded by heating and pressure. Further, a thermosetting epoxy or urethane adhesive may be used as the adhesive. Furthermore, an acrylic ultraviolet adhesive may be used. By bonding A cell and B cell together as described above, reflection at the interface between both cells can be reduced.

[Example 20] FIG. 35 shows an example of a structure in which a film-like polymer layer (hereinafter referred to as A film) is used as an optically anisotropic body. In the figure, 3536 is an upper polarizing plate, 3537 is an upper A film, 3538 is a B cell, 3539 is a lower A film, and 3540 is a lower polarizing plate. Moreover, FIG. 36 is a diagram showing the relationship between each axis of a liquid crystal device using A film.

In the figure, 3645 is the rubbing direction of the upper electrode substrate of the B cell, 3646 is the rubbing direction of the lower electrode substrate of the B cell, 3647 is the direction of the optical axis of the upper A film, and 3648 is the rubbing direction of the upper electrode substrate of the B cell.
is the direction of the optical axis of the lower A film, 3649 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, 3650 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 3651 is the polarization axis of the upper polarizing plate (absorption axis) direction 3649 and the optical axis direction 3647 of the upper A film, 3652 is the angle between the optical axis direction 3647 of the upper A film and the rubbing direction 3645 of the upper electrode substrate of the B cell, 3653 is the twist angle size of the liquid crystal of B cell, 3654 is the rubbing direction 3646 of the lower electrode substrate of B cell and the direction 3 of the optical axis of the lower A film.
64, the angle 3655 is the direction 3 of the optical axis direction 3648 of the lower A film and the polarization axis (absorption axis) of the lower polarizing plate.
This is the angle formed with 650.

In the same figure, the angle 3651 is about 40 degrees, the angle 3652 is about 90 degrees, and the angle 3653 is about 200 degrees.
The rubbing direction 3646 of the lower electrode substrate of the B cell and the direction 36 of the polarization axis (absorption axis) of the lower polarizing plate without inserting the film.
50 is approximately 40 degrees. Further, the product Δn·d of the refractive index anisotropy Δn of the upper A film and the layer thickness d of the upper A film is approximately 0.55 μm, and Δn−d of the B cell is approximately 0°9 μm. At this time as well, the external color of the liquid crystal display device is approximately white in the off state and approximately black in the on state.

This A film uses a uniaxially stretched film of DAC, PET, cellulose diacetate, PVA, polyamide, polyethersulfone, acrylic, polysulfone, polyimide, polyolefin, or the like.

Examples using A film will be described below.

[Example 21] In Fig. 36, the angle 3651 is approximately 50 degrees, and the angle 36
52 is approximately 90 degrees, the twist angle 3653 of the B cell liquid crystal is approximately 200 degrees left-handed, the angle 3654 is approximately 90 degrees, and the angle 3
655 is approximately 50 degrees.

Also, Δn-d of the upper A film and Δn of the lower A film
The sum of n−d is approximately 0.6 μm, and Δn−d of B cell
is approximately 0.9 μm. Also in this case, the same effect as in Example 20 can be obtained.

[Example 22] In Fig. 36, when the structure is such that there is no lower A film, Δn-d of the upper A film is approximately 0°55 μm1, the angle 3651 is approximately 50 degrees, the angle 3652 is approximately 90 degrees, and the B cell is The helix angle of the liquid crystal is approximately 250 degrees to the left, B
The angle between the rubbing direction 3646 of the lower electrode substrate of the cell and the direction 3650 of the polarization axis (absorption axis) of the lower polarizing plate is approximately 5
Even when the temperature is 0 degrees and Δn-d of the liquid crystal of cell B is about 0.9 μm, the external appearance of the liquid crystal device is almost white in the off state and almost black in the on state.

[Example 23] In FIG. 36, there is no lower A film, and the upper A film consists of 11 films whose optical axes are shifted from top to bottom by 15 degrees in a clockwise direction, and the Δn- d
The sum of these is approximately 0.7 μm.

Furthermore, the angle between the polarization axis (absorption axis) of the upper polarizing plate and the direction of the optical axis of the top layer of the upper A film is approximately 50.
The angle between the optical axis direction of the lowermost film of the upper A film and the rubbing direction of the upper electrode substrate of the B cell is approximately 90 degrees, and the angle between the rubbing direction of the lower electrode substrate of the B cell and the lower polarizing plate is approximately 90 degrees. The angle with the polarization axis (absorption axis) is approximately 40 degrees,
The twist angle 3653 of the liquid crystal in cell B is approximately 200 degrees to the left, and Δn-d of the liquid crystal in cell B is approximately 0.9 μm. At this time, the external appearance of the liquid crystal device is approximately white in the off state, and approximately black in the on state.

[Example 24] In FIG. 35, when the structure is such that there is no lower A film 3539, Δn-d of the upper A film 3537 is approximately 0.65 to 0.85 μm, and the angle 3651 in FIG. 36 is 3.
5 degrees to 55 degrees, angle 3652 from 80 degrees to 100 degrees,
The helix angle 3653 of the liquid crystal of the B cell is approximately 200 degrees to the left, and the angle between the rubbing direction 3646 of the lower electrode substrate of the B cell and the direction 3650 of the polarization axis (absorption axis) of the lower polarizing plate is set to 35 55 degrees, the Δn-d of the B cell liquid crystal is approximately 0.
It was set to 9 μm.

The external appearance of this liquid crystal device was almost white in the off state and almost black in the on state.

[Example 25] In FIG. 35, when the structure is such that there is no lower A film 3539, Δn-d of the upper A film 3537 is approximately 0.25 to 0.45 μm, and the angle 3651 in FIG.
5 degrees to 55 degrees, angle 3652 from 80 degrees to 100 degrees,
The helix angle 3653 of the liquid crystal of the B cell is approximately 200 degrees to the left, and the angle between the rubbing direction 3646 of the lower electrode substrate of the B cell and the direction 3650 of the polarization axis (absorption axis) of the lower polarizing plate is set to 35 55 degrees from the degree, the Δn-d of the B cell liquid crystal is approximately 0
．． It was set to 9 μm. The external appearance of this liquid crystal device was almost white in the off state and almost black in the on state.

[Example 26] In FIG. 35, when the structure is such that there is no lower A film 3539, Δn-d of the upper A film 3537 is approximately 0.4 to 0.6 μm, and the angle 3651 in FIG. 36 is 35 degrees. from 55 degrees, angle 3652 from 80 degrees to 100 degrees, B cell liquid crystal torsion angle 3653 to the left of about 180 degrees,
The angle between the rubbing direction 3646 of the lower electrode substrate of cell B and the direction 3650 of the polarization axis (absorption axis) of the lower polarizing plate is 3
From 5 degrees to 55 degrees, the Δn-d of the B cell liquid crystal is approximately 0°9μ
It was set as m.

The external appearance of this liquid crystal device was almost white in the off state and almost black in the on state.

[Example 27] In FIG. 35, when the structure is such that there is no lower A film 3539, Δn-d of the upper A film 3537 is approximately 0.5 to 0.7 μm, the angle 3651 is 35 degrees to 55 degrees, The angle 3652 in FIG. 36 is from 80 degrees to 100 degrees, and the twist angle 3653 of the liquid crystal in cell B is approximately 180 degrees to the left.
The angle between the rubbing direction 3646 of the lower electrode substrate of cell B and the direction 3650 of the polarization axis (absorption axis) of the lower polarizing plate is 3
From 5 degrees to 55 degrees, the △n-d of the B cell liquid crystal is approximately 1°0μ
It was set as m.

The external appearance of this liquid crystal device was almost white in the off state and almost black in the on state.

[Example 28] In FIG. 35, when the structure is such that there is no lower A film 3539, Δn-d of the upper A film 3537 is approximately 0.5 to 0.6 μm, and the angle 3651 in FIG. 36 is 35 degrees. from 55 degrees, angle 3652 from 80 degrees to 100 degrees, B cell liquid crystal twist angle 3653 about 230 degrees to the left,
The angle between the rubbing direction 3646 of the lower electrode substrate of cell B and the direction 365o of the polarization axis (absorption axis) of the lower polarizing plate is 3
From 5 degrees to 55 degrees, the Δn-d of the B cell liquid crystal is approximately 0°9μ
It was set as m.

The external appearance of this liquid crystal device was almost white in the off state and almost black in the on state.

[Example 29] In Examples 20 to 28, a structure in which the A film is integrated with a polarizing plate is used. FIG. 37 shows a model of the structure when the polarizing plate and the A film are integrated. In the figure, 3756 is a protective film for the polarizing plate, 3757 is a polarizer, 3758 is an A film, and 3759 is a protective film for the polarizing plate. A similar effect can be obtained even when the A film is integrated with a polarizing plate and used in a liquid crystal device as shown in the figure.

(Example 30) In Examples 1 to 29, a reflective liquid crystal device with black and white display can be obtained regardless of whether the reflective plate is placed outside the upper or lower polarizing plate.

[Example 31] Instead of using the A film shown in Example 20 as the optical anisotropic body, a liquid crystalline polymer film exhibiting a cholesteric phase (hereinafter referred to as the Ach film) was used as the optical anisotropic body. An example of the case will be described in detail.

FIG. 38 shows the structure when an Ach film is used as the optically anisotropic body. In the figure, 3861 is the upper polarizing plate, 3862 is the Ach film, 3863 is the B cell, and 38
64 is an upper electrode substrate of the B cell, 3865 is a liquid crystal of the B cell, 3866 is a lower electrode substrate of the B cell, and 3867 is a lower polarizing plate.

Moreover, FIG. 39 is a diagram showing the relationship between each axis of a liquid crystal display device using an Ach film. In the figure, 3968 is the rubbing direction of the lower electrode substrate of the B cell, 3969 is the rubbing direction of the upper electrode substrate of the B cell, 3970 is the long axis direction of the liquid crystal molecules adjacent to the B cell of the Ach film, and 397 is the rubbing direction of the lower electrode substrate of the B cell.
1 is the long axis direction of the liquid crystal molecules adjacent to the upper polarizing plate of the Ach film, 3972 is the direction of the polarizing axis (absorption axis) of the lower polarizing plate, 3973 is the direction of the polarizing axis (absorption axis) of the upper polarizing plate, 3974 is the size of the torsion angle of the liquid crystal in cell B, 397
5 is the angle between 3970 and 3969, 3976
3977 is the angle between 3973 and 3971, 3977 is the angle between 3968 and 3972, and 3978 is the angle between 3971 and 3970.

Here, the polarizing plate, Ach film, and B cell were arranged as shown in FIG. 38, and the conditions for each axis were set as follows.

The B cell was assembled so that the helix angle 3974 of the liquid crystal of the B cell was approximately 200 degrees to the left, and Δn-d was 0.9 μm. On the other hand, the angle of the Ach film is 3978
is adjusted so that it has a right helix of approximately 330 degrees, Δn-d is approximately 1.05 μm in terms of a uniaxially stretched film, and an angle of 3
975 from 80 degrees to 100 degrees, angles 3976 and 39
77 was set in the range of 40 degrees to 50 degrees, and liquid crystal devices were manufactured. When the transmitted light spectrum of the liquid crystal device was measured at this time, the external color was almost white in the off state and almost black in the on state.

In this example, a mixture of polypeptide and polymethyl methacrylate was used as the Ach film.

[Example 32] In FIG. 39, the B cell was assembled so that the helix angle 3974 of the liquid crystal of the B cell was twisted to the left by about 200 degrees, and Δn-d was 0°9 μm. On the other hand, when the Ach film is turned around, the angle 3978 is approximately 360 degrees right-handed, and Δn-
d is adjusted to be about 1.0 μm in terms of uniaxially stretched film, angle 3975 is adjusted in the range of 80 degrees to 100 degrees, and angles 3976 and 3977 are adjusted in the range of 40 degrees to 5 degrees, respectively.
A liquid crystal device was manufactured by setting the temperature in the 0 degree range.

At this time as well, the exterior color was almost white in the off state and almost black in the on state.

[Example 33] In FIG. 39, the B cell was assembled so that the helix angle 3974 of the liquid crystal of the B cell was twisted to the left by about 200 degrees, and Δn-d was 0°9 μm. On the other hand, the Ach film is plotted, and the angle 3978 is approximately 210 degrees right-handed, △n-
Adjust so that d is about 0.95 μm in terms of uniaxially stretched film, angle 3975 is in the range of 80 degrees to 100 degrees, angle 3976 is in the range of 40 degrees to 50 degrees, angle 39
77 was set in the range of 40 degrees to 50 degrees to manufacture a liquid crystal device.

At this time as well, the exterior color was almost white in the off state and almost black in the on state.

[Example 34] In FIG. 39, the B cell was assembled so that the helix angle 3974 of the liquid crystal of the B cell was twisted to the left by about 180 degrees, and Δn-d was 0°9 μm. On the other hand, when the Ach film is turned around, the angle 3978 is approximately 180 degrees right-handed, and Δn-
Adjust so that d is about 0.9 μm in terms of uniaxially stretched film, angle 3975 is in the range of 80 degrees to 100 degrees, angle 3976 is in the range of 40 degrees to 50 degrees, angle 397
7 was set in the range of 40 degrees to 50 degrees, and a liquid crystal device was manufactured.

At this time as well, the exterior color was almost white in the off state and almost black in the on state.

[Example 35] In Examples 31 to 34, the same results as in Examples 31 to 34 were obtained even when a mixture of a polymer and a low molecular liquid crystal was used instead of the liquid crystalline polymer film.

[Example 36] In Examples 31 to 34, a polymer film made of a mixture of TN liquid crystal ZLI3285 manufactured by Merck and chiral dopant CB-15 manufactured by BDH and low polymerized polymethyl methacrylate-1 was used as the Ach film. In this case, the same effects as in Examples 31 to 34 were obtained.

[Example 37] In Examples 31 to 36, even when a reflective plate was used outside the upper polarizing plate or the lower polarizing plate, the color was almost white in the off state and almost black in the on state.

〔Effect of the invention〕

The present invention has solved the coloring phenomenon, which was a major drawback of conventional STNTN type liquid crystal devices. In other words, the present invention enables complete black and white display. Not only that, but the amount of light in the transmitted state increased, resulting in a brighter display. Furthermore, the amount of leaked light in the non-transmissive state was extremely reduced, and together with the increase in the amount of light in the transparent state, the contrast ratio was greatly improved.

Due to the above effects, the present invention was able to exhibit good color display characteristics when applied to color display. In particular, when the twist angle was 180 degrees or more, the clear vision direction was the front, and the clear vision area was a region close to concentric circles centered on the front. Therefore, as a full-color image display element, conventional TN
Wider viewing angle and direction of viewing angle compared to those using a TN-type LCD device (for TN-type devices, the diagonal direction is the clear viewing direction)
, contrast ratio, etc. have been greatly improved. Naturally, color display (8-color display) without gradation display is also improved compared to the TN type.

Since the above effects can be obtained regardless of the thickness of the liquid crystal layer of the display liquid crystal cell, the present invention can easily realize a high-speed response display device by thinning the liquid crystal layer of the display liquid crystal cell. be able to. This is because the response speed is approximately proportional to the square of the thickness of the liquid crystal layer.

Furthermore, since the present invention is effective in improving the contrast ratio as described above, it is also effective in increasing the number of drive lines in multiplex drive.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a typical example of the liquid crystal device of the present invention. FIG. 2 is a diagram showing the optical characteristics of the liquid crystal device according to the present invention in an off state. FIG. 3 is a diagram showing the relationship between a liquid crystal cell, a polarizing plate, and an optically anisotropic body in a liquid crystal device of the present invention. FIG. 4 is a diagram showing the off-state spectrum of the liquid crystal device according to the present invention. FIG. 5 is an xy chromaticity diagram in which the off-state spectrum of the liquid crystal device according to the invention shown in FIG. 4 is plotted on color coordinates. FIG. 6 is a diagram conceptually showing a case where the optical anisotropic body does not completely inversely transform the transformation of the liquid crystal cell. FIG. 7 is a diagram showing the relationship between each axis direction when a film-like polymer is used as the optically anisotropic body in the liquid crystal device of the present invention. FIG. 8 is a diagram showing a spectral curve under the conditions shown in Example 20. FIG. 9 is an xy chromaticity diagram showing the spectral curve shown in FIG. 8 in color coordinates. FIG. 10 is a diagram showing another configuration example of the liquid crystal device of the present invention. FIG. 11(a) is a diagram schematically depicting a cross section of the liquid crystal layer divided into ten parts. FIG. 11(b) is a diagram conceptually showing the relationship between the liquid crystal layer thickness and helix angle in FIG. 11(a). Figure 12 shows the wavelength 450 calculated by dividing the liquid crystal layer into 20.
FIG. 3 is a diagram showing the transition of the polarization state of nm light. Figure 13 shows the wavelength 550 calculated by dividing the liquid crystal layer into 20.
FIG. 3 is a diagram showing the transition of the polarization state of nm light. Figure 14 shows the calculated wavelength of 650 when the liquid crystal layer is divided into 20 parts.
FIG. 3 is a diagram showing the transition of the polarization state of nm light. FIG. 15 shows a polarizing plate 2 used in a specific example of the present invention.
A diagram showing the wavelength dependence of the light transmittance of the sheet. FIG. 16 is a diagram showing an example of a method for driving the shielding crystal device of the present invention. FIG. 17 is a schematic diagram of a conventional super twisted nematic liquid crystal device. FIG. 18 is a diagram showing the optical characteristics of a conventional 5TN-LCD in an off state. FIG. 19 is a diagram showing the relationship between a liquid crystal cell of a conventional liquid crystal device and a polarization axis (absorption axis) of a polarizing plate. FIG. 20 is a diagram showing spectra of light transmittance of pixels in an on state and pixels in an off state during multiplex driving of a conventional liquid crystal device. FIG. 21 is an xy chromaticity diagram in which the spectral curve shown in FIG. 20 is plotted on color coordinates. FIG. 22 is a diagram showing the structure of a liquid crystal device in an embodiment of the present invention. FIG. 23 is a diagram showing the relationship between each axis of the liquid crystal device of the present invention. FIG. 24(a) shows the twist angle and Δn of the liquid crystal of cell A when the conditions of cell B are fixed in Example 1 of the present invention.
The figure which showed the desirable range of Xd. FIG. 24(b) is a diagram showing the relationship of Y(i) to Δn−d when the range of FIG. 24(a) is derived by calculation. FIG. 25 is an external appearance of a liquid crystal device according to Example 2 of the present invention. Figure 26 is a diagram showing the relationship between the external wavelength and transmittance characteristics of a liquid crystal device according to Example 3 of the present invention. A diagram showing the relationship between external wavelength and transmittance characteristics of the liquid crystal device of Example 4. Figure 28 shows the torsion angle of the liquid crystal of cell A when the conditions of cell B are fixed in the example of the present invention. A diagram showing a desirable range of 31 is a diagram showing the desired range of the torsion angle and ΔnXd of the liquid crystal of the A cell when the conditions of the B cell are fixed. FIG. The twist angle of the liquid crystal of cell A and ΔnXd
A diagram showing a desirable range of . FIG. 32 shows the torsion angle and ΔnXd of the liquid crystal of cell A when the conditions of cell B are fixed in Example 11 of the present invention.
A diagram showing a desirable range of . FIG. 33 shows the torsion angle and ΔnXd of the liquid crystal of cell A when the conditions of cell B are fixed in Example 12 of the present invention.
A diagram showing a desirable range of . FIG. 34 is a diagram showing the structure of a liquid crystal device according to Example 14 of the present invention. FIG. 35 is a diagram showing the structure of a liquid crystal device according to Example 20 of the present invention. FIG. 36 is a diagram showing the relationship between each axis of a liquid crystal device according to Example 21 of the present invention. FIG. 37 is a diagram showing the structure of a polarizing plate of a liquid crystal device according to Example 29 of the present invention. FIG. 38 is a diagram showing the structure of a liquid crystal device according to Example 31 of the present invention. FIG. 39 is a diagram showing the relationship between each axis of a liquid crystal device according to Example 31 of the present invention. 11, 18, 3861, 3867 are polarizing plates, 12, 38
63 is a liquid crystal cell, and 19.3862 is an optically anisotropic body (liquid crystal polymer film). Yatsu quarrel old ○ rOrf) Spider spit must be a sloppy body -〇-〇ya Kei・Light × 〉 Kirikiri − r − i ~ Yume de Vtsu

Claims (1)

[Claims] (1) A liquid crystal cell consisting of a nematic liquid crystal twisted at an angle of 120° or more sandwiched between a pair of substrates with electrodes formed on opposing inner surfaces, and at least one layer of a liquid crystalline polymer that is an optically anisotropic material. A film is provided between a pair of polarizing plates, and the light incident on one polarizing plate is transmitted between the liquid crystal cell and the liquid crystalline polymer film adjacent to the liquid crystal cell by a long wavelength for each wavelength. The liquid crystalline polymer film is arranged so that the light becomes elliptically polarized light with different axial directions, and then becomes elliptically polarized light with substantially the same major axis direction for each wavelength when it enters the other polarizing plate. liquid crystal device.