JPH09325316A - Liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal device which enables a black and white display and is suitable for a color display by conducting the inverse transformation of the optical transformation performed by a liquid crystal cell against the light beams made incident on the cell over the entire wavelengths by an optical anisotropic body. SOLUTION: This device is formed by arranging a liquid crystal 12 which is made by holding the liquid crystal 17 that is twist oriented for more than 120 degrees and held between a pair of opposing substrates 13 and 13 and a single layer optical anisotropic body 19 between a pair of polarizing plates 11 and 18. Then, the angle between the optical axis direction of the surface which opposes against the cell 12 of the body 19 and the rubbing direction made on a substrate 13 of the side, on which the body 19 of the cell 12 is arranged, is set to approximately 90 degrees. Moreover, the body 19 has the characteristics to conduct the inverse transformation of the optical transformation performed by the cell 12 against the light beams made incident on the cell 12, over the entire wavelengths. Thus, a perfect black and white display is obtained, the light quantity in a passing condition is increased and a brighter display is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device, and more particularly to a super twisted nematic liquid crystal device.

[0002]

2. Description of the Related Art A conventional super twisted nematic type (hereinafter referred to as STN type) liquid crystal device is disclosed in Japanese Unexamined Patent Publication No. Sho 60-90.
The twist angle of liquid crystal molecules is 90 as in Japanese Patent Publication No. 505511.
And a pair of polarizing plates above and below the liquid crystal cell,
The included angle formed by these polarization axes (absorption axes) and the molecular axis directions of the liquid crystal molecules adjacent to the electrode substrate was in the range of 30 to 60 degrees. Therefore, due to the birefringence coloring, the hue of the appearance when no voltage is applied to the liquid crystal cell is not white, but is generally a hue from green to yellow-red. In addition, the hue of the appearance when the selection voltage is applied is generally blue instead of black.

FIG. 17 is a schematic view 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 ITO electrode is formed on a substrate 173, and an alignment film 175 is further applied and subjected to rubbing treatment. The upper and lower substrates are spacers 17.
The liquid crystal 177 is sandwiched between the liquid crystal 177 and the liquid crystal 177. Reference numeral 178 is a lower polarizing plate.

FIG. 19 is an explanatory view showing the relationship between the liquid crystal cell and the polarization axis (absorption axis) of the polarizing plate in the above liquid crystal device. In the figure, 190 is the rubbing direction of the upper electrode substrate of the liquid crystal cell, and 191 is the rubbing direction. The rubbing direction of the lower electrode substrate of the liquid crystal cell, 192 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, 1
94 is the size of the twist angle of the liquid crystal molecules of the liquid crystal cell, and 195
Is an angle formed by the rubbing direction 190 of the upper electrode substrate and the direction 192 of the polarization axis (absorption axis) of the upper polarizing plate, and 196 is the rubbing direction 191 of the lower electrode substrate and the polarization axis (absorption axis) of the lower polarizing plate. The angle formed by the direction 193 is shown.

In FIG. 19, the angle 194 is set to 200.
And the angles 195 and 196 are approximately 50 degrees, respectively, and the product Δn · d of the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer.
FIG. 2 shows the optical characteristics of the liquid crystal device when the thickness is 0.9 μm.
0 is shown.

This figure shows a multiplex driving method which is usually used as a driving method for a liquid crystal device of this type.
FIG. 7 shows spectra of light transmittance of a pixel in an ON state and a pixel in an OFF state in a positive mode (bright when no electric field is applied) when the liquid crystal device is driven.

The off state means a state in which no electric field is applied, or a state in which the molecular orientation is maintained in a substantially no applied state even when an electric field is applied, and the on state means a molecular orientation of liquid crystal. It means a state in which the change is necessary and sufficient to cause an optical change.

The curve I in FIG. 20 is in the off state,
Curve II shows the spectrum of the pixel in the ON state,
Curve I is "bright" Curve II is "dark" In other words, it can be seen that curves I and II can be visually distinguished.

[0009]

However, when the spectrum shown in FIG. 20 is plotted on the color coordinates,
As shown in FIG. 21, it can be seen that in the conventional liquid crystal device, the off state is colored yellow in the positive mode and the blue state is colored in the on state.

As described above, in the prior art, when the positive mode is selected, the off-state appearance colors of the liquid crystal device are green, yellowish green,
It is colored yellow or yellow-red, and when it is on, it becomes blue or dark blue. In the negative mode (dark when no voltage is applied), it is dark blue in the off state and yellow in the on state.

These colors are not colors generally preferred as display colors for liquid crystal devices. After all, as for the display color of the liquid crystal device, the combination of white and black, that is, the combination of flat spectra is the most psychologically and physically most suitable in terms of spectrum. Has been. Especially when performing color display by combining with a color filter,
Whether or not the spectrum is flat has a great influence on the vividness of the color, and it is difficult to display blue and red with high brightness, apart from green, by the conventional method whose spectrum is shown in FIG. Become.

By the way, in a twisted nematic type (hereinafter referred to as TN type) liquid crystal device as a means for eliminating the above-mentioned coloring, a twisted nematic type liquid crystal display cell of a single layer type without a power feeding means is provided. A liquid crystal device having a two-layer structure in which liquid crystal layers are superposed is known (see, for example, JP-A-57-96315).

However, the liquid crystal device disclosed in the above publication is not directly applicable to the STN type liquid crystal device described above. That is, the liquid crystal device described in the above publication is a so-called TN type. That is, the twist angle is 90
The polarizing plate is arranged in parallel or orthogonal to the direction of the adjacent liquid crystal molecules, and its operating principle utilizes optical activity. Therefore, it is significantly different from the STN type structure that positively utilizes the birefringence as the operating principle.
It cannot be applied to a STN type liquid crystal device as it is.

The present invention solves the above problems, and an object of the present invention is to provide a liquid crystal device capable of monochrome display, and further to provide a liquid crystal device suitable for color display. It is in.

[0015]

In a liquid crystal device of the present invention, a liquid crystal display device is provided between a pair of substrates having electrodes formed on opposing inner surfaces.
A pair of polarizing plates, having a liquid crystal cell sandwiching a nematic liquid crystal twisted and oriented by more than °, and at least one layer of a liquid crystalline polymer film which is an optically anisotropic body,
Light incident on one of the polarizing plates becomes elliptically polarized light having a different major axis direction for each wavelength between the liquid crystal cell and the liquid crystal polymer film adjacent to the liquid crystal cell, and then enters the other polarizing plate. In this case, the above-mentioned problems are solved by a liquid crystal device characterized in that the liquid crystalline polymer film is arranged so as to be elliptically polarized light in which the major axis direction is substantially uniform for each wavelength.

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

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

In the structure of the liquid crystal cell 12, a transparent electrode 14 is formed on a substrate 13, an alignment film 15 is further formed, and a rubbing treatment is performed. Spacer 16 for the upper and lower substrates
The liquid crystal 17 is sandwiched between the liquid crystal 17 and the liquid crystal 17.

The polarizing plate, liquid crystal material, liquid crystal alignment method, liquid crystal element driving method and the like used in the present invention are the same as those generally known in the conventional TN type or STN type liquid crystal device. Is applicable. The details will be described below.

The optical characteristics are greatly affected by the polarization characteristics of the polarizing plate used. Although LLC2-82-18 manufactured by Sanritsu Electric Co., Ltd. is used in all of the specific examples of the present invention described below, it goes without saying that the present invention is not limited to this. FIG. 15 shows the wavelength dependence of the light transmittance of the two polarizing plates. In the figure, I is a spectrum curve when a pair of polarizing plates are arranged parallel to each other, and II is a spectrum curve when they are arranged perpendicularly to each other. The liquid crystal composition used in the present invention is a nematic liquid crystal having a positive dielectric anisotropy. An example of a preferable liquid crystal is SS-4008 manufactured by Chisso Corporation. The following is also an example of another preferable liquid crystal composition.

[0021]

Embedded image

A chiral dopant is preferably added to the liquid crystal composition in order to keep the twisted structure of the liquid crystal stable.

As the chiral dopant, for example, CB-15 manufactured by BDH can be used to obtain a right-handed helical structure, and S-811 manufactured by Merck can be used to form a left-handed helical structure.

The display liquid crystal cell 12 used in the present invention may have the same structure as the liquid crystal cell 172 used in the prior art shown in FIG.

In FIG. 1, the substrate 13 is made of glass, for example.
A transparent substrate such as plastic is used. A transparent electrode 14 made of, for example, ITO is formed on the substrate, and an alignment film layer 15 that determines the alignment of liquid crystals is formed on the transparent electrode 14.

Polyimide, polyvinyl alcohol and the like are preferable examples of the alignment layer. Generally, by rubbing these alignment film layers, the liquid crystal can be given a certain alignment. Further, as another method of aligning the liquid crystal, an oblique vapor deposition method of SiO or the like can be used.

An example of the driving method of the liquid crystal device of the present invention is shown in FIG. The multiplex driving method shown in the figure is a method that is generally used at present and has been put to practical use, but other driving methods can be used in the present invention. As the optically anisotropic body 19 used in the present invention, for example, a liquid crystal composition, a uniaxially stretched film, a liquid crystalline polymer film, a film made of a mixture of liquid crystal and a polymer compound, or the like is used. When the liquid crystal composition is used, smectic liquid crystal, cholesteric liquid crystal, nematic liquid crystal and the like can be used. Specifically, it is also desirable to use a nematic liquid crystal, and further, a nematic liquid crystal which is the same as the display cell. As the uniaxially stretched film, for example, a film obtained by uniaxially stretching polyvinyl alcohol, polyester, polyetheramide, polyethylene or the like can be used. In the liquid crystal polymer film, for example, a polypeptide-polymethacrylate mixed film can be used. Further, not only the polypeptide but also other liquid crystalline polymers can be used, but specifically, a liquid crystalline polymer showing a cholesteric phase is desirable. The structural formula is shown below as an example.

[0028]

Embedded image

When a film made of a mixture of liquid crystal and polymer is used as an optically anisotropic substance, for example, P
A liquid crystal composition in which a chiral dopant is mixed with a low molecular weight liquid crystal such as CH-based, CCH-based, or biphenyl, and a helical structure is mixed with a polymer such as polymethyl methacrylate, polyvinyl acetate, or polyamide is used. Can be used. A preferred example of the liquid crystal composition mixed in the polymer is shown.

[0030]

Embedded image

[0031]

The novel point of the present invention is that the STN type liquid crystal device of the prior art is provided with an optically anisotropic body in order to prevent coloring. The function of this optical anisotropic body will be described in detail below.

FIG. 18 shows the conventional STN shown in FIG.
FIG. 18 is an explanatory diagram of optical characteristics of a liquid crystal device in an off state, in which 181 denotes incident light. The incident light 181 is generally natural light, includes light of all wavelengths in the visible region, and has a random polarization direction. The incident light 181 is the linear polarization plate 1
Linearly polarized light 1831
It is a set of 1832, 1833, etc. Where 1831
1832 and 1833 have wavelengths of 450 nm and 550, respectively.
nm and 650 nm are shown. Naturally, linearly polarized light of other wavelengths is also included, but here, only these three wavelengths are shown as representative wavelengths of three colors of blue, green and red. These linearly polarized lights 1831, 1832, 1833 then pass through the liquid crystal cell 184. The liquid crystal layer in the liquid crystal cell has a structure in which nematic liquid crystals exhibiting optically uniaxial refractive index anisotropy are twisted. How the polarization state changes when the linearly polarized light 1831, 1832, 1833, etc. passes through the liquid crystal layer having such a structure can be predicted by the method described later. For example, the results of the above-mentioned conventional liquid crystal device whose spectrum is shown in FIG. 20 are 1851, 1852 and 185, respectively.
The polarization state is as shown in FIG. By passing through the liquid crystal layer in this way, wavelength dispersion occurs in the polarization state. These polarized lights 1851, 1852 and 1853 finally pass through the linear polarization plate 186. As for 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 above-mentioned conventional liquid crystal device whose spectrum is shown in FIG. 20, it becomes 1871, 1872, and 1873, respectively. The amount of light with a wavelength of 550 nm is larger than this,
It can be seen that the amounts of light of nm and 650 nm are small. A spectral representation of these results is I in FIG. 20, and a plot of this on the color coordinates in FIG.
I. As described above, the conventional STN type liquid crystal device had to be colored due to wavelength dispersion due to birefringence.

Next, an explanatory view of the optical characteristics of the liquid crystal device according to the present invention in the off state is shown in FIG. Comparing FIG. 18 and FIG. 2, FIG. 2 is different from FIG. 18 in that an optical anisotropic body 28 is added as a constituent element. For convenience of explanation, the conditions of the components other than the optically anisotropic body 28 and the polarizing plate 26 are the same as those in the conventional example shown in FIG.
It is assumed to be the same as the liquid crystal device whose spectrum is shown in FIG.

Therefore, in FIG. 2, the polarization states 251, 25 of the respective wavelengths after passing through the polarizing plate 22 and the liquid crystal cell 24.
2.253 is 1851, 1852, 1853 of FIG.
Is exactly the same as The difference is that each of the polarized lights 251, 252 and 253 in FIG. In the present invention, this optically anisotropic body 28 is the polarized light 231, 232, 2.2.
The optical anisotropic body has a function of canceling the wavelength dispersion caused by the passage of 33 through the liquid crystal cell 24.

In order to explain this action in an easy-to-understand manner,
The optical function of the liquid crystal cell 24 is defined as M. Further 231
・ The polarization state of 232 ・ 233 is P, 251, 252 ・ 2
Assuming that the polarization state of 53 is P ′, P ′ is obtained from P and M by the following equation.

P '= M * P (1) Here, it is assumed that the optical function of the optical anisotropic body 28 is a function M ^-1 for performing the inverse transformation of M. 291, 292, 293
Let P ″ be the polarization state of P ′ and P ″ can be obtained from the following equation from P ′ and M ⁻¹ .

P ″ = M ⁻¹ * P ′ (2) The following equation is obtained from the above equations (1) and (2).

P ″ = M ⁻¹ * M * P (3) Obviously, M ⁻¹ * M = 1 (4) Therefore, P ″ = P ・ ・ ・ (5) Equation (5) above Indicates that the polarization states (P ″) of 291, 292 and 293 are the same as the polarization states (P) of 231, 232 and 233, respectively.
Since 2 · 233 is the polarized light immediately after the natural light 21 has passed through the linear polarizing plate 22, all the wavelengths are linear polarized light having a vibration direction corresponding to the orientation of the polarizing plate 22. Therefore 291
292 and 293 are also linearly polarized light having a vibration direction in the same direction as 231, 232 and 233. When the polarization axis direction of the linearly polarizing plate 26 matches the vibration direction of the polarized light 291, 292, 293, this linearly polarized light passes through the linearly polarizing plate 26 as it is and becomes 271, 272, 273.

The spectrum of the emitted light at this time coincides with the spectrum of the polarizing plate shown in I of FIG. 15 (however, the light absorption in the liquid crystal cell and the optically anisotropic body is neglected). The spectrum of the polarizing plate is almost flat and colorless. As described above, the liquid crystal device according to the present invention can eliminate the coloring phenomenon in the off state.

Although the main points of the present invention have been described above, the problem is that the linearly polarized light 231, 232 incident on the liquid crystal cell 24 in FIG.
Is there actually an optical anisotropic body that can perform the reverse conversion of the conversion performed by the liquid crystal cell 24 on 233 or the like over all wavelengths? In conclusion, the inventors have found that such a condition of the optical anisotropic body 28 may exist. Moreover, such a condition is the liquid crystal cell 2
We have found that it can exist regardless of the conditions of 4.

In order to explain this condition, the relationship among the liquid crystal cell, the polarizing plate and the optically anisotropic body in the liquid crystal device of the present invention shown in FIG. 1 is shown in FIG. 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 surface facing the optically anisotropic liquid crystal cell, and 34 is The optical axis direction of the surface of the optically anisotropic plate facing the polarizing plate, 35 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 36 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, and 37 is An angle formed by the direction 36 of the polarization axis of the upper polarizing plate and the optical axis direction 34 of the optically anisotropic body, 38
Is the angle formed by the optical axis directions 33 and 34 of the optically anisotropic body, and 39
Is the angle formed by 33 and 32, 40 is the size of the twist angle of the liquid crystal layer in the liquid crystal cell, and 30 is the rubbing direction 3 of the liquid crystal cell.
It is the angle between 1 and the direction 35 of the polarization axis of the lower polarizing plate.

Here, for example, the conditions of the liquid crystal cell are shown in FIG.
Exactly the same conditions as those of the conventional positive mode liquid crystal device whose spectrum is shown in FIG. 1, that is, whitening conditions when the twist angle 40 of the liquid crystal layer in the liquid crystal cell is 200 degrees and Δn · d is 0.9 μm. Describe. When there is no optically anisotropic substance, the spectrum naturally becomes as shown in FIG. However, for example, a liquid crystal cell is used as the optically anisotropic body, and when the twist angle 38 of the liquid crystal layer is −200 degrees (that is, the absolute value of the twist angle is equal to that of the display liquid crystal cell due to reverse twist), Δn · d is 0. 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 45 degrees for 37, 45 degrees for 30, and 90 degrees for 39 in FIG. FIG. 5 is a plot of the spectrum shown in FIG. 4 on the color coordinates. FIG. 2
It can be seen that the color is almost white as compared with the conventional method shown in FIG.

As shown in the above example, the condition of the optically anisotropic body 28 for performing the reverse conversion of the liquid crystal cell 24 as shown in FIG. 2 is present regardless of the wavelength. This correspondence is shown below. That is, (1) Δn · d of liquid crystal cell and Δn · d of optically anisotropic body
Are equal in absolute value.

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

(3) The angle 39 formed by the optical axis direction 33 of the surface facing the optically anisotropic 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 satisfied, the coloring in the off state of the liquid crystal device can be completely eliminated, that is, whitening can be performed regardless of the value of Δn · d and the value of twist angle θ.

The above description is all about the mechanism for eliminating the coloring in the off state. In the present invention, coloring in the ON state is also eliminated.
It is not impossible to explain exactly the reason for eliminating the coloring in the ON state, but it is complicated. In any case, the inventor has experimentally confirmed that there is no or almost no on-state coloring even under various conditions, as shown in many examples in Examples described later.

As described above, in order to completely eliminate the coloring in the positive mode off state, the above three conditions must be satisfied. However, in reality, it is often practically sufficient that the optically anisotropic substance does not completely reverse the conversion of the liquid crystal cell as shown in FIG. This is shown conceptually in FIG. FIG. 6 corresponds to FIG. The difference from FIG. 2 is that the states 691, 692, and 693 of the respective polarizations after passing through the optically anisotropic body 68 are 291.
This means that it is slightly elliptically polarized light instead of perfect linearly polarized light like 292 and 293. As a result, the polarizing plate 6
The polarized light 671, 672, 673 after passing through No. 6 has a slight wavelength dependence in its intensity. For example, a spectrum under the conditions shown in Example 20 described later is plotted in FIG. 8 and in FIG. 9 the spectrum is plotted on color coordinates. Under the conditions shown in Example 20, the polarization state after passing through the optically anisotropic body is elliptical polarization as in 691, 692 and 693 in FIG. Nevertheless, the coloring is almost completely eliminated as shown in FIG. Incidentally, FIG. 7 shows the relationship between the optically anisotropic body, the liquid crystal cell and each axis of the polarizing plate in this case.

As described above, even under the conditions where the above three conditions are not satisfied, there are practically conditions for the optically anisotropic substance that can sufficiently eliminate the coloring.

Alternatively, for other reasons, it may be more desirable to use an optically anisotropic substance other than the above three conditions in a positive sense. One of the reasons is that the characteristics of the polarizing plate generally have wavelength dependence. An example of this is shown in FIG. By appropriately selecting the conditions of such an optically anisotropic substance as such wavelength characteristics, the coloring as a liquid crystal device can be improved. This applies not only to the off state but also to the on state. Another reason is to change the condition of the optical anisotropic body in consideration of the wide viewing angle.

The various conditions of the optical anisotropic body in the structure shown in FIG. 1 have been described above. In the configuration shown in FIG. 1, the optically anisotropic body is 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.

FIG. 10 shows another structural example of the liquid crystal device of the present invention. 10 is different from the configuration of FIG. 1 in that optical anisotropic bodies are present both above and below the liquid crystal cell. Even with such a configuration, it is possible to effectively eliminate the coloring completely as shown in FIG. As a matter of course, it is possible to almost completely eliminate the coloring as shown in FIG.

The above description is for the state in which the transmittance in the off state is high, that is, the positive mode. Next, a description will be given of a low transmittance state in the off state, that is, a negative mode. If the direction of the polarization axis of the polarizing plate 26 of FIG. 2 is set to be orthogonal to the polarization axis of the polarizing plate 22, the polarization 29
Neither 1.292 nor 293 can pass through the polarizing plate 26. Therefore, the spectrum of the transmitted light at this time coincides with the spectrum of the polarizing plate in the crossed Nicol state shown in II of FIG. 15 (however, the light absorption in the liquid crystal cell and the optically anisotropic body, etc. is ignored). This state is the darkest state that can be obtained using the polarizing plate shown in FIG. As described above, in the present invention, the use of the optically anisotropic substance makes it possible to obtain the desired flat spectral characteristics even in the negative mode. That is, coloring can be eliminated in any case. The following description will be made on the positive mode.

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

The light incident on the optically anisotropic body is generally elliptically polarized light. The reference plane trace of elliptically polarized light that advances in the positive direction of the Z axis can be expressed as follows by a column vector having xy components as elements.

[0056]

[Equation 1]

Here, ax and ay are the amplitudes of the xy components, ω is the angular frequency, and ψx and ψy are the phase angles of the xy components. However, in this case, the absolute phase of the wave does not matter, so the optical frequency and absolute phase terms in Eq. (6) are omitted, and the polarization state is determined by the following normalized Jones vector that also normalizes the amplitude of each component. Described.

[0058]

[Equation 2]

The polarized light E of the formula (7) passes through an optically anisotropic body and changes its polarization state to become polarized light E '. The optically anisotropic body is represented by a 2 × 2 Jones matrix that performs this conversion.

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

[0061]

(Equation 3)

Here, θ represents an angle formed by the fast axis of the linear retarder and the X axis, and Δ represents retardation. The retardation Δ is the linear retarder Δn · d and the wavelength λ of the light.
Is defined by Δ≡2πΔn · d / λ.

The polarization state of the light that has passed through the film polymer is obtained from the left side of the incident light vector E by applying the Jones matrix R of the equation (8) as follows.

[0064]

(Equation 4)

When the optically anisotropic body is formed by stacking a plurality of film-like polymers, the light is sequentially passed from the left side of the incident light vector E in the order in which light passes.
By applying the Jones matrix of Eq. (8), it is calculated as follows.

[0066]

(Equation 5)

When the optically anisotropic substance is a liquid crystal cell,
Since the liquid crystal molecules are twisted and aligned, the phase shifter is complicated. However, if the liquid crystal layer is divided into a large number of layers as shown in FIG. 11A, it can be approximated by stacking liquid crystal layers that are not twisted and oriented as shown in FIG. 11B. Since the liquid crystal layer that is not twist-aligned is a uniaxial linear retarder that is the same as the film-like polymer, polarization of the light passing through the liquid crystal cell is performed in the same manner as when a plurality of film-like polymers described above are stacked. You can ask for status.

Using the method described above, the angle 4 in FIG.
0 is 200 degrees, angle 38 is minus 200 degrees, angle 30
Is 45 degrees, the angle 37 is 45 degrees, the angle 39 is 90 degrees, and Δn · d of each of the liquid crystal cell for display and the optically anisotropic body is 0.9 μm. Transitions of polarization states of light calculated by dividing are shown in FIGS. 12 to 14. 12 and 13 and 14 respectively show changes in polarization state of light having wavelengths of 450 nm, 550 nm and 650 nm. For example, in the case of FIG. 12, linearly polarized light 12 incident on the display liquid crystal cell in FIG.
In No. 1, the polarization state transits to 122, 123, and 124 after passing through five layers, and the cell emits 125 elliptically polarized light. This elliptically polarized light 125 continues to be incident on the optically anisotropic body in FIG.
The polarization state shifts to 7.128, and the optically anisotropic body is emitted with 129 linearly polarized light. In each of the above steps, the conversion of the polarization state by the optically anisotropic body in FIG. 11B corresponds to the inverse conversion of the conversion by the display liquid crystal cell in FIG. The light incident on the cell is
The optically anisotropic substance is emitted with exactly the same polarization state. As is clear from FIGS. 13 and 14, this effect exists regardless of the wavelength of light. Therefore, in the liquid crystal display device of the present invention, coloring in the off state is completely eliminated and whitening is possible. Becomes

Further, as described above, there is a condition of an optically anisotropic substance which can sufficiently eliminate the coloring even if the above three conditions are not satisfied. The condition is that the light incident on one polarizing plate becomes elliptically polarized light having different major axis directions for each wavelength between the liquid crystal cell and the optically anisotropic body adjacent to the liquid crystal cell, and then the other When the light is incident on the polarizing plate, the above-mentioned optical anisotropic body may be arranged so as to be elliptically polarized light whose wavelengths are substantially aligned in the major axis direction. Specifically, the condition of the optically anisotropic body may be set appropriately according to the twist angle of the display liquid crystal cell and the value of Δn · d, and the condition will be specifically described below based on Examples.

[0070]

22 is a cross-sectional view schematically showing the structure of a liquid crystal device when liquid crystal is used as an optically anisotropic body in the liquid crystal device of the present invention. In the figure,
Reference numeral 2201 denotes an upper polarizing plate, 2202 denotes a liquid crystal cell in which liquid crystal as an optically anisotropic body is sandwiched between two substrates (hereinafter referred to as A cell), 2203 denotes an upper substrate of the A cell, and 2204 denotes a lower side of the A cell. Substrate, 2205 is a liquid crystal used as an optically anisotropic body, 2206 is a liquid crystal cell (hereinafter referred to as B cell) for displaying by applying a voltage, 2207 is an upper electrode substrate of B cell, 2208 is a lower electrode substrate of B cell. Reference numeral 2209 denotes a B cell liquid crystal, and 2210 denotes a lower polarizing plate.
FIG. 23 is a diagram showing the relationship of 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 the B cell, 2312 is the rubbing direction of the upper electrode substrate of the B cell, 2313 is the rubbing direction of the lower substrate of the A cell, and 2314 is the upper substrate of the A cell. Rubbing direction, 23
15 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 2316
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, 231.
8 is the magnitude of the liquid crystal twist angle in the A cell, and 2319 is the angle between the rubbing direction 2313 of the lower substrate of the A cell and the rubbing direction 2312 of the upper electrode substrate of the B cell, 2320.
Is the magnitude of the twist angle of the liquid crystal in the B cell, and 2321 is the angle between the rubbing direction 2311 of the lower electrode substrate of the B cell and the polarization axis (absorption axis) direction 2315 of the lower polarizing plate. Hereinafter, the twist direction of the liquid crystal molecules in each cell will be indicated by the twist direction from the top to the bottom of the cell.

[Embodiment 1] In FIG. 23, the twist angle 2320 of the liquid crystal of the B cell is a left twist of about 200 degrees, and Δn ·
d about 0.9 μm, angle 2319 about 90 degrees, angle 23
When 17 is in the range of 30 degrees to 60 degrees and the angle 2321 is in the range of 30 degrees to 60 degrees, when the twist angle 2318 and Δn · d of the liquid crystal of the A cell are the shaded portions in FIG. 24 (a), It is possible to obtain a liquid crystal device which becomes substantially white in the off state and almost black in the on state.

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

That is, Δn · d twisted to the left by 200 °
= 0.9 μm B-cell liquid crystal in the thickness direction of the cell 20
Divide into 0, and one layer of Δn · d = 0.0045 μm
The calculation is performed by the above calculation formula assuming that the axial retarder has a structure in which it is twisted by 1 ° to the left. The wavelength of the light used at this time is in the range of 400 nm to 700 nm. In addition, the polarization state of the light incident on the liquid crystal of the B cell is
Although different depending on the type of polarizing plate used and the direction of the axis, an ideal polarizing plate (transmissivity 50% for parallel Nicols, transmittance 0% for crossed Nicols) is used here. The angle formed by the rubbing direction of the substrate adjacent to the polarizing plate (direction of liquid crystal molecules on the substrate surface) and the direction of the polarization axis of the polarizing plate is 45 °. Then, the linearly polarized light that has passed through the polarizing plate is incident on the B cell, and the elliptically polarized state of the light of each wavelength that has passed through the B cell is obtained.

Next, the state of the elliptically polarized light after this elliptically polarized light has entered and passed through the A cell is determined. The elliptically polarized light incident on the A cell is obtained by the same calculation as above, and the angle formed by the rubbing directions of the adjacent substrates of the A cell and the B cell is 90 degrees. In addition, the liquid crystal of the cell A is also divided into 200 in the cell thickness direction, and the uniaxial retarder is twisted by 0.7 degrees to the right and twisted by 140 degrees to the right as a whole. When Δn · d of is an appropriate value, the state of elliptically polarized light passing through the A cell can be obtained from the above calculation formula. further,
Here, an angle between the rubbing direction of the substrate adjacent to the polarizing plate and the direction of the polarizing axis of the polarizing plate is set to 45 degrees, the spectrum after passing through the polarizing plate is obtained, and the Y value after the luminosity correction is obtained.

In the above calculation, Δn of the liquid crystal of cell A
The relationship between Δn · d of the A cell and the luminosity-corrected Y value is determined by setting the value of d from 0 μm to 1.5 μm. At this time, if Δn · d of cell A is plotted on the horizontal axis and the Y value is plotted on the vertical axis, FIG.
As shown in (b), the Y value has a maximum value and a minimum value and changes periodically. Since there are two directions in which the angle formed by the polarization axis and the rubbing direction is 45 degrees, two curves are drawn in FIG. 24 (b). Display modes include a negative mode (dark when no voltage is applied) and a positive mode (bright when no voltage is applied). In the negative mode, it is desirable that the no-voltage application state is darker, and in the positive mode, the no-voltage application state is brighter. Therefore, FIG.
4 (b), the part where the Y value is maximum is suitable for the positive mode, and the part where the Y value is minimum is suitable for the negative mode.

The Y value of the conventional negative mode voltage applied state is as high as about 5%, and it is recognized that the Y value is clearly colored blue visually and on the color coordinates.

On the other hand, Y which is the minimum in FIG.
The value is less than half the Y value of the negative mode of the conventional STN type liquid crystal device. The color at this time is slightly colored on the color coordinates, but the Y value is small, so it is visually recognized as a color sufficiently close to black. It is recognized as white when a voltage is applied. Therefore, in the negative mode, black and white display can be obtained in the area where the Y value is the minimum, so that Δn
The value d is obtained. The portion where the Y value is maximum becomes closer to white in visual observation and in color coordinates, as compared with the color in the state where no voltage is applied in the conventional positive mode. However, it is close to white even before and after the portion where the Y value is maximum. Therefore, in the positive mode, a black and white display can be obtained in a fairly wide range, and it is very difficult to judge the boundary.
Moreover, since the angle formed by the polarization axis and the rubbing direction is 45 degrees, the direction of the polarization axis in the case of one curve in FIG.
When it is shifted by a certain degree, it coincides with the polarization axis of the other curve.
Therefore, the maximum and minimum values of Δn · d in FIG. 24B are the same.

From the above, what is black and white is Δn · d at which the Y value is minimum. In other words, cell B has a left-handed twist of 2
When Δn · d = 0.9 μm at 00 degrees, the angle formed between 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 is 45 degrees, and the substrate adjacent to the B cell and the A cell is The angle formed by each rubbing direction is 90 degrees, and A
When the cell is twisted to the right by 140 degrees and the angle formed by 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, Δn · d of the A cell is 0.
Black and white display is obtained when 33 μm, 0.7 μm, 1.0 μm, and 1.3 μm (when Δn · d of A cell is 1.5 μm or less) (see FIG. 24B).

Next, when 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 not 45 degrees, or the rubbing direction of each of the adjacent substrates of the B cell and the A cell is set. The calculation is performed in the same procedure when the angle is other than 90 degrees. Then, Δn · d of the A cell having the minimum Y value is obtained as a range having a certain width and periodically appearing (the distribution of Δn · d when the twist angle is fixed at 140 degrees to the right in FIG. 24 (a)). ). However, the angle formed by the directions of the respective axes at this time is within a range in which the minimum Y value is 3% or less, or there is no extreme coloring.

The condition of cell B is left unchanged and A
Even when only the magnitude of the twist angle of the cell is changed, the range of Δn · d of the A cell where the Y value becomes the minimum appears periodically as in the above. The relationship between the magnitude of the twist angle of cell A and Δn · d thus obtained is summarized in FIG.
4 (a). That is, from FIG. 24A, when the B cell has a left twist of 200 degrees and Δn · d is 0.9 μm, the magnitude of the twist angle of the A cell and Δ which obtains a black and white display.
It can be seen that there is not only one condition of n · d, but a certain fan-shaped range exists periodically.

Further, the magnitude of the twist angle of B cell and Δn
Even when d is changed, the magnitude of the twist angle and Δn · d of the A cell for obtaining a monochrome display can be obtained by the same procedure as above. Also in this case, the size of the twist angle of cell A and Δ
The relationship of n · d becomes fan-shaped and appears periodically.

In this way, the twist angle and Δn · d of the A cell for displaying in black and white can be obtained for the twist angle and Δn · d of the arbitrary B cell. Δn · d is not unique and exists in large numbers.

[Embodiment 2] In Embodiment 1, the angle 2317 in FIG. 23 is about 40 degrees, and the twist angle 23 of the liquid crystal of the A cell is 23.
18 right twist about 140 degrees, angle 2319 about 90
, The twist angle 2320 of the liquid crystal of the B cell is a left twist of about 200 degrees, the angle 2321 is about 40 degrees, and the Δ of the liquid crystal layer of the A cell is
The n · d is about 0.7 μm, and the Δn · d of the liquid crystal layer of the B cell is about 0.9 μm. The appearance spectrum of the liquid crystal device at this time is shown in FIG. In the figure, curve I shows the off state and curve II shows the on state. The spectrum of the appearance of the liquid crystal device according to the related art shown in FIG. 20 is yellow when it is off (curve I) and blue when it is on (curve II). However, as shown in FIG. 25, the liquid crystal device of the present invention is substantially white in the off state and almost black in the on state.

[Third Embodiment] In the first embodiment, the angle 2317 in FIG. 23 is set to about 40 degrees, and the twist angle 23 of the liquid crystal of the A cell is 23.
18 about 200 degrees right twist, angle 2319 about 90 degrees
Degree, the twist angle 2320 of the liquid crystal of the B cell is a left twist of about 200 degrees, the angle 2321 is about 50 degrees, and the Δ of the liquid crystal layer of the A cell is Δ.
The n · d is about 0.9 μm, and the Δn · d of the liquid crystal layer of the B cell is about 0.9 μm. FIG. 26 shows the external appearance spectrum of the liquid crystal device at this time. In the figure, curve I shows the off state and curve II shows the on state. Also in this case, the second embodiment
Similarly, in the off state, it is almost white, and in the on state, it is almost black.

[Embodiment 4] In Embodiment 1, the angle 2317 in FIG. 23 is about 40 degrees, and the twist angle 23 of the liquid crystal of the A cell is 23.
18 right twist about 260 degrees, angle 2319 about 90 degrees
, The twist angle 2320 of the liquid crystal of the B cell is a left twist of about 200 degrees, the angle 2321 is about 40 degrees, and the Δ of the liquid crystal layer of the A cell is
The n · d is about 0.8 μm, and the Δn · d of the liquid crystal layer of the B cell is about 0.9 μm. The appearance spectrum of the liquid crystal device at this time is shown in FIG. In the figure, curve I shows the off state and curve II shows the on state. Also in this case, similar to the second and third embodiments, the white state is almost white in the off state and the black state is almost black in the on state.

[Embodiment 5] In FIG. 23, the twist angle 2320 of the liquid crystal of the B cell is a left twist of about 250 degrees, and Δn ·
d about 0.9 μm, angle 2319 about 90 degrees, angle 23
When 17 is in the range of 30 degrees to 60 degrees and the angle 2321 is in the range of 30 degrees to 60 degrees, when the twist angle 2318 and Δn · d of the liquid crystal of the A cell are indicated by the hatched portion in FIG. A liquid crystal device which becomes white and becomes almost black in the on state is obtained.

[Embodiment 6] In Embodiment 5, the angle 2317 in FIG. 23 is set to about 40 degrees, and the twist angle 23 of the liquid crystal of the A cell is 23.
18 right twist about 160 degrees, angle 2319 about 90
Degree, the twist angle 2320 of the liquid crystal of the B cell is a left twist of about 250 degrees, the angle 2321 is about 40 degrees, and the Δ of the liquid crystal layer of the A cell is
The n · d is about 0.8 μm, and the Δn · d of the liquid crystal layer of the B cell is about 0.9 μm. The external appearance spectrum of the liquid crystal device at this time is shown in FIG. In the figure, curve I shows the off state and curve II shows the on state. Also in this case, the second embodiment
Similarly, in the off state, it is almost white, and in the on state, it is almost black.

[Embodiment 7] In FIG. 23, an angle 231 is set.
7 is about 40 degrees, and the twist angle 2318 of the A cell liquid crystal is about 3 degrees.
The right twist of 60 degrees, the angle 2319 is about 90 degrees, the twist angle 2320 of the liquid crystal of the B cell is about 250 degrees, and the angle 2321 is about 40 degrees, and Δn of the liquid crystal layer of the A cell is further increased.
・ D is about 1.0 μm, and Δn · d of the B cell liquid crystal layer is about 0.9 μm. At this time, the liquid crystal device becomes white in the off state and more black in the on state.

[Embodiment 8] In FIG. 23, an angle 231
7 is about 50 degrees, and the twist angle 2318 of the A cell liquid crystal is about 1
The right twist of 70 degrees, the angle 2319 is about 90 degrees, the twist angle 2320 of the liquid crystal of the B cell is about 170 degrees, the left twist is about 170 degrees, and the angle 2321 is about 40 degrees.
・ D is about 0.7 μm, and Δn · d of the liquid crystal layer of the B cell is about 0.7 μm. At this time, the liquid crystal device becomes white in the off state and becomes blacker in the on state.

[Embodiment 9] In FIG. 23, the twist angle 2320 of the liquid crystal of the B cell is twisted to the left by about 120 degrees, and Δn ·
d about 0.9 μm, angle 2319 about 90 degrees, angle 23
When 17 is in the range of 30 degrees to 60 degrees and the angle 2321 is in the range of 30 degrees to 60 degrees, when the twist angle 2318 and Δn · d of the liquid crystal of the A cell are the shaded portions in FIG.
It is possible to obtain a liquid crystal device which becomes substantially white in the off state and almost black in the on state.

[Embodiment 10] In FIG. 23, the twist angle 2320 of the liquid crystal of the B cell is left twisted by about 200 degrees, and Δn
・ D is about 0.6 μm, angle 2319 is about 90 degrees, and angle 2
When 317 is in the range of 30 degrees to 60 degrees and the angle 2321 is in the range of 30 degrees to 60 degrees, when the twist angle 2318 and Δn · d of the liquid crystal of the A cell are the shaded portions in FIG. A liquid crystal device which becomes white and becomes almost black in the on state is obtained.

[Embodiment 11] In FIG. 23, the twist angle 2320 of the liquid crystal of the B cell is left twisted by about 200 degrees, and Δn
・ D about 1.5 μm, angle 2319 about 90 degrees, angle 2
When 317 is in the range of 30 degrees to 60 degrees and the angle 2321 is in the range of 30 degrees to 60 degrees, when the twist angle 2318 and Δn · d of the liquid crystal of the A cell are shown by the shaded portion in FIG. A liquid crystal device which becomes white and becomes almost black in the on state is obtained.

[Embodiment 12] In FIG. 23, the twist angle 2320 of the liquid crystal of the B cell is twisted to the left by about 350 degrees, and Δn
・ D is about 0.9 μm, angle 2319 is about 90 degrees, angle 2
When 317 is in the range of 30 degrees to 60 degrees and the angle 2321 is in the range of 30 degrees to 60 degrees, when the twist angle 2318 and Δn · d of the liquid crystal of the A cell are shown by the hatched portion in FIG. A liquid crystal device which becomes white and becomes almost black in the on state is obtained.

[Embodiment 13] In Embodiments 1 to 12, the same effect can be obtained even if the A cell and the B cell are arranged upside down. The lower substrate 2 of the A cell shown in FIG.
Similar effects can be obtained by replacing the two substrates of 204 and the upper electrode substrate 2207 of the B cell with one substrate.

[Embodiment 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, and 3426 is a lower polarizing plate. In the liquid crystal device having the structure shown in FIG.
3, the liquid crystal molecules in the lower A cell 3425 are twisted to the right. The liquid crystal molecules of the B cell 3424 are left-handed.
The sum of the twist angle of the liquid crystal molecules of the upper A cell 3423 and the twist angle of the liquid crystal molecules of the lower A cell 3425 at this time is taken as the twist angle of the entire A cell, and Δn · d of the liquid crystal layer of the upper A cell 3423 is calculated. Δn of the liquid crystal layer of the lower A cell 3425
The sum of d and Δn · d of the entire A cell. This A
The twist angle of the entire cell and Δn · d of the entire A cell are shown in Example 1.
Even under the conditions of the A cell from to Example 12, the same effects as those from Example 1 to Example 12 can be obtained. The same effect can be obtained even if the arrangement order of the cells 3423, 3424, and 3425 is arbitrarily changed. Further, the A cell may be provided in three or more layers under the same conditions as above.

[Embodiment 15] In the structure of Embodiment 14, the lower substrate 3429 of the upper A cell 3423 and the B cell 3 are used.
The two substrates of the upper electrode substrate 3430 of 424 are replaced with one substrate. Further, the lower electrode substrate 3432 of the B cell 3424 and the upper electrode 3433 of the lower A cell 3425 are
Replace one substrate with one substrate. By doing so, the number of substrates is reduced, the structure is simplified, and the same effect as that of the fourteenth embodiment is obtained.

[Embodiment 16] In Embodiments 1 to 15, the temperature T _A (K) at the liquid crystal NI point of the A cell and the temperature T _B (K) at the NI point of the liquid crystal of the B cell are set. At this time, if a liquid crystal with 0.86 ≦ T _A / T _B ≦ 1.15 is used, even if Δn · d of the liquid crystal layers of B cell and A cell changes due to temperature change, the appearance color of the liquid crystal device is almost It does not change.

[Embodiment 17] In Embodiments 1 to 16, when a liquid crystal having a positive dielectric anisotropy Δε is used as the liquid crystal of the A cell, alignment of the liquid crystal of the A cell is affected by static electricity from the outside. May be disturbed and color unevenness may appear in 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 in which appearance color unevenness does not occur even if there is an influence of static electricity from the outside.

[Embodiment 18] In Embodiments 1 to 16, electrodes are attached to the inside of the upper and lower substrates of the A cell, and the liquid crystal of the A cell having a positive Δε is used. By doing so, even if the color of the appearance of the liquid crystal device changes due to the temperature change, it is possible to cancel the color change by applying a voltage between the electrodes attached to the upper and lower substrates of the A cell.

[Embodiment 19] In Embodiments 1 to 18 except Embodiments 13 and 15, cells A and B are used.
The A cell and the B cell are optically adhered to each other in order to prevent reflection of light on the surface of the substrate in contact with the cell. The polyvinyl butyral film that has been embossed is used as the adhesive layer, and the adhesive is applied by heating and pressing. Alternatively, a thermosetting epoxy-based or urethane-based adhesive may be used as the adhesive. Further, an acrylic ultraviolet adhesive may be used. By adhering the A cell and the B cell as described above, it is possible to reduce reflection at the boundary surface between the two cells.

[Embodiment 20] FIG. 35 shows an example of the structure in which a film polymer layer (hereinafter referred to as A film) is used as an optically anisotropic body. In the figure, 3536 is the upper polarizing plate, 3537 is the upper A film, and 3538 is B.
A cell, 3539 is a lower A film, and 3540 is a lower polarizing plate.

FIG. 36 is a diagram showing the relationship of each axis of the liquid crystal device using the A film. In the figure, 364
5 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 optical axis of the upper A film, 3648 is the optical axis direction of the lower A film, and 3649 is 3650 is the direction of the polarization axis (absorption axis) of the lower polarizing plate, 3651 is the direction of the polarization axis (absorption axis) of the upper polarizing plate 3650
An angle formed by 649 and the optical axis direction 3647 of the upper A film, 3652 is 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 size of the twist angle of the liquid crystal of the B cell,
3654 is a rubbing direction 364 of the lower electrode substrate of the B cell
6 is an angle formed by the optical axis direction 3648 of the lower A film, and 3655 is an angle formed by the optical axis direction 3648 of the lower A film and the polarization axis (absorption axis) direction 3650 of the lower polarizing plate.

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 angle formed with the direction 3650 of the polarization axis (absorption axis) of the side polarizing plate is about 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 about 0.55 μm, and the Δ of the B cell is
n · d is about 0.9 μm. Also at this time, the appearance color of the liquid crystal display device is almost white in the off state and almost black in the on state.

As the A film, a uniaxially stretched film such as DAC, PET, cellulose diacetate, PVA, polyamide, polyether sulfone, acrylic, polysulfone, polyimide or polyolefin is used.

Examples using the A film will be described below.

[Embodiment 21] In FIG. 36, an angle 36
51 is about 50 degrees, the angle 3652 is about 90 degrees, the twist angle 3653 of the liquid crystal of the B cell is about 200 degrees left twist, the angle 3
654 is about 90 degrees, and angle 3655 is about 50 degrees. Also, Δn · d of the upper A film and Δn of the lower A film
-Adding d is about 0.6 μm, and Δn · d of B cell is about 0.9 μm. Also in this case, the same effect as that of Example 20 can be obtained.

[Embodiment 22] In FIG. 36, when the structure without the lower A film is used, Δn.
d about 0.55 μm, angle 3651 about 50 degrees, angle 3
652 is about 90 degrees, the twist angle 3653 of the liquid crystal of the B cell is about 250 degrees left twist, and the rubbing direction 3646 of the lower electrode substrate of the B cell and the polarization axis (absorption axis) direction 3650 of the lower polarizing plate. The angle is about 50 degrees, and the Δn
Even when d is about 0.9 μm, the appearance color of the liquid crystal device is almost white in the off state and almost black in the on state.

[Embodiment 23] In FIG. 36, there is no lower A film, and the upper A film is 1 from top to bottom.
It is composed of 11 films whose optical axes are shifted in the right-handed twist direction by 5 degrees, and the sum of Δn · d is about 0.7 μm.
Further, the angle formed by the polarization axis (absorption axis) of the upper polarizing plate and the direction of the optical axis of the uppermost film of the upper A film is about 50.
The angle between the direction of the optical axis of the lowermost film of the upper A film and the rubbing direction of the upper electrode substrate of the B cell is about 90 °, and the rubbing direction of the lower electrode substrate of the B cell and the lower polarizing plate The angle between the polarization axis (absorption axis) is about 40 degrees,
The twist angle 3653 of the liquid crystal of the B cell is twisted to the left by about 200 degrees, and Δn · d of the liquid crystal of the B cell is set to about 0.9 μm. At this time, the appearance color of the liquid crystal device is almost white in the off state and almost black in the on state.

[Embodiment 24] In FIG. 35, when the lower A film 3539 is not provided, Δn · d of the upper A film 3537 is about 0.65 to 0.85 μm, and the angle 3651 of FIG. 55 degrees from the angle, angle 3652
80 degree to 100 degree, the twist angle of B cell liquid crystal is 365
3 is a left twist of about 200 degrees, and the angle formed by the rubbing direction 3646 of the lower electrode substrate of the B cell and the polarization axis (absorption axis) direction 3650 of the lower polarizing plate is 35 degrees to 55 degrees. Δn · d of about 0.9 μm.

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

[Embodiment 25] In FIG. 35, when the lower A film 3539 is not provided, Δn · d of the upper A film 3537 is about 0.25 to 0.45 μm, and the angle 3651 of FIG. 55 degrees from the angle, angle 3652
80 degree to 100 degree, the twist angle of B cell liquid crystal is 365
3 is a left twist of about 200 degrees, the rubbing direction 3646 of the lower electrode substrate of the B cell and the polarization axis (absorption axis) direction 3650 of the lower polarizing plate make an angle of 35 degrees to 55 degrees, and the liquid crystal of the B cell. Δn · d of about 0.9 μm. The appearance color of the liquid crystal device was almost white in the off state and almost black in the on state.

Example 26 In FIG. 35, when the lower A film 3539 is not provided, Δn · d of the upper A film 3537 is about 0.4 to 0.6 μm.
Angle 3651 of 35 degrees to 55 degrees, angle 3652 of 8
0 to 100 degrees, the twist angle 3653 of the liquid crystal of the B cell is twisted to the left by about 180 degrees, and 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. The angle formed was 35 ° to 55 °, and Δn · d of the B cell liquid crystal was about 0.9 μm.

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

[Embodiment 27] In FIG. 35, when the lower A film 3539 is not provided, Δn · d of the upper A film 3537 is about 0.5 to 0.7 μm and the angle is 3.
651 from 35 degrees to 55 degrees, and angle 3652 in FIG.
0 to 100 degrees, the twist angle 3653 of the liquid crystal of the B cell is twisted to the left by about 180 degrees, and 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. The angle formed was 35 to 55 degrees, and Δn · d of the liquid crystal of the B cell was about 1.0 μm.

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

[Embodiment 28] In FIG. 35, when the lower A film 3539 is not provided, Δn · d of the upper A film 3537 is about 0.5 to 0.6 μm.
Angle 3651 of 35 degrees to 55 degrees, angle 3652 of 8
0 to 100 degrees, the twist angle 3653 of the liquid crystal of the B cell is twisted to the left by about 230 degrees, and 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. The angle formed was 35 ° to 55 °, and Δn · d of the B cell liquid crystal was about 0.9 μm.

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

[Embodiment 29] Embodiments 20 to 28
In A, the A film is integrated with the polarizing plate. FIG. 37 shows a model of the structure in which the polarizing plate and the A film are integrated. In the figure, 3756 is a polarizing plate protective film, 3757 is a polarizer, 3758 is an A film, and 3759 is a polarizing plate protective film. Similar effects can be obtained by using the A film together with the polarizing plate in the liquid crystal device as shown in FIG.

[Embodiment 30] In Embodiments 1 to 29, a black and white reflective liquid crystal device can be obtained by placing the reflection plate on the outer side of either the upper or lower polarizing plate.

[Example 31] A liquid crystal polymer film showing a cholesteric phase (hereinafter referred to as an Ach film) is used as an optical anisotropic body instead of using the A film shown in Example 20 as an optical anisotropic body. An example of the case used as 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 an upper polarizing plate, 3862 is an Ach film, 3863 is B.
Cell, 3864 is B cell upper electrode substrate, 3865 is B cell
Cell liquid crystal, 3866 is B cell lower electrode substrate, 386
7 is a lower polarizing plate.

Further, FIG. 39 is a diagram showing the relationship of each axis of the liquid crystal display device using the Ach film. In the figure, 3968 is the rubbing direction of the lower electrode substrate of the B cell, and 3968.
69 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, 3971 is the long axis direction of the liquid crystal molecules adjacent to the upper polarization plate of the Ach film, 3972 is the direction of the polarization axis (absorption axis) of the lower polarization plate, 3973 is the direction of the polarization axis (absorption axis) of the upper polarizing plate, 3974 is the size of the twist angle of the liquid crystal of B cell, 3975 is the angle formed by the 3970 and 3969, 3976 is the angle formed by the 3973 and 3971, 3977 is an angle formed by the 3968 and the 3972, and 3978 is an angle formed by the 3971 and the 3970.

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

The twist angle 3974 of the liquid crystal of the B cell is set to about 20.
0 degree left twist, so that Δn · d becomes 0.9 μm B
The cell was assembled. On the other hand, the Ach film was previously adjusted so that the angle 3978 was right-twisted at about 330 degrees and Δn · d was converted to a uniaxially stretched film to be about 1.05 μm, and the angle 3975 was set at 80 degrees to 100 degrees, and the angle 397 was set.
Liquid crystal devices were manufactured by setting 6 and 3977 in the range of 40 to 50 degrees. When the transmitted light spectrum of the liquid crystal device at this time was measured, the appearance color was almost white in the off state and almost black in the on state.

In this example, as an Ach film, a polypeptide and pormethylmethacrylate [Example 32] In FIG. 39, the twist angle 3974 of the liquid crystal of cell B was twisted to the left by about 200 degrees and Δn · d was 0.9.
The B cell was assembled to have a size of μm. On the other hand, the Ach film is twisted to the right at an angle of 3978 by about 360 degrees in advance, and Δn · d is converted to a uniaxially stretched film by about 1.0.
Adjust to an angle of 3975 from 80 degrees to 1
The liquid crystal device was manufactured by setting the range of 00 degrees and the angles 3976 and 3977 to the range of 40 degrees to 50 degrees.

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

[Embodiment 33] In FIG. 39, the twist angle 3974 of the liquid crystal of the B cell is left twisted by about 200 degrees, and Δn
B cell was assembled so that d was 0.9 μm. On the other hand, with Ach film, the angle 3978 is set to about 2 in advance.
10 degree right twist, Δn · d converted into a uniaxially stretched film, adjusted to be about 0.95 μm, angle 3975
Was set in the range of 80 degrees to 100 degrees, the angle 3976 was set in the range of 40 degrees to 50 degrees, and the angle 3977 was set in the range of 40 degrees to 50 degrees to manufacture a liquid crystal device.

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

[Embodiment 34] In FIG. 39, the twist angle 3974 of the liquid crystal of the B cell is left twisted by about 180 degrees, and Δn
B cell was assembled so that d was 0.9 μm. On the other hand, for Ach film, the angle 3978 is set to about 1 in advance.
Right twist of 80 degrees, Δn · d converted into a uniaxially stretched film is adjusted to be about 0.9 μm, angle 3975 is in the range of 80 to 100 degrees, angle 3976 is in the range of 40 to 50 degrees, The liquid crystal device was manufactured by setting the angle 3977 in the range of 40 degrees to 50 degrees.

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

Example 35 The same results as in Examples 31 to 34 were obtained even when a mixture of a polymer and a low molecular weight liquid crystal was used in place of the liquid crystalline polymer film in Examples 31 to 34.

Example 36 In Examples 31 to 34, TN liquid crystal ZLI3 manufactured by Merck Ltd. was used as the Ach film.
285 and BDH Chiral Dopant CB-15
The same effect as in Examples 31 to 34 was obtained also when a polymer film made of a mixture of and low-polymerized polymethylmethacrylate was used.

[Embodiment 37] In Embodiments 31 to 36, when a reflection plate was used outside the upper polarizing plate or the lower polarizing plate, it was almost white in the off state and almost black in the on state.

[0134]

According to the present invention, the coloring phenomenon, which is a major drawback of the conventional STN type liquid crystal device, can be solved. In other words, the present invention enables perfect black and white display. Not only that, but the amount of light in the transmitted state increased, resulting in a bright display. Furthermore, the amount of leak light in the non-transmissive state was extremely small, and the contrast ratio was greatly improved in combination with the increase in the amount of light in the transmissive state.

Due to the above effects, the present invention can 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 region near the front and close to the concentric circles was the clear vision region. Therefore, as compared with the one using a conventional TN type liquid crystal device as a full color image display element, the width of the viewing angle, the direction of the viewing angle (in the TN type, the oblique direction is the clear viewing direction), the contrast ratio. Have been greatly improved. Naturally, the color display (8-color display) without gradation display is also improved as compared with the TN type display.

The present invention can obtain the above effect regardless of the thickness of the liquid crystal layer of the display liquid crystal cell. Therefore, by decreasing the thickness of the liquid crystal layer of the display liquid crystal cell, a high-speed response display device can be easily manufactured. Can be realized. This is because the response speed is approximately proportional to the square of the thickness of the liquid crystal layer.

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

[Brief description of drawings]

FIG. 1 is a diagram showing a typical example of a liquid crystal device of the present invention.

FIG. 2 is a diagram showing optical characteristics of a liquid crystal device in an off state according to the present invention.

FIG. 3 is a diagram showing a relationship among a liquid crystal cell, a polarizing plate, and an optically anisotropic body in the liquid crystal device of the present invention.

FIG. 4 is a diagram showing an off-state spectrum of the liquid crystal device according to the present invention.

5 is an xy chromaticity diagram in which an off-state spectrum of the liquid crystal device according to the present invention shown in FIG. 4 is put on color coordinates.

FIG. 6 is a diagram conceptually showing a case where an optically anisotropic body does not completely reverse the conversion of the liquid crystal cell.

FIG. 7 is a diagram showing a relationship in each axial direction when a film polymer is used as an optically anisotropic body in the liquid crystal device of the present invention.

FIG. 8 is a diagram showing a spectrum curve under the conditions shown in Example 20.

FIG. 9 is an xy chromaticity diagram showing the spectrum 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. 11A is a diagram schematically illustrating a cross section when the liquid crystal layer is divided into 10 parts. FIG. 3B is a view conceptually showing the relationship between the liquid crystal layer thickness and the twist angle in FIG.

FIG. 12 shows a wavelength 450 calculated by dividing a liquid crystal layer into 20 parts.
The figure which showed the transition of the polarization state of the light of nm.

FIG. 13 shows a wavelength 550 calculated by dividing the liquid crystal layer into 20 parts.
The figure which showed the transition of the polarization state of the light of nm.

FIG. 14 shows a wavelength 650 calculated by dividing a liquid crystal layer into 20 parts.
The figure which showed the transition of the polarization state of the light of nm.

FIG. 15 is a polarizing plate 2 used in a specific example of the present invention.
The figure which showed the wavelength dependence of the light transmittance of a sheet.

FIG. 16 is a diagram showing an example of a driving method of the liquid crystal device of the present invention.

FIG. 17 is a schematic view of a conventional super twisted nematic liquid crystal device.

FIG. 18 is a diagram showing optical characteristics of a conventional STN-LCD in an off state.

FIG. 19 is a diagram showing a relationship between a polarization axis (absorption axis) of a liquid crystal cell of a conventional liquid crystal device and a polarizing plate.

FIG. 20 is a diagram showing spectra of light transmittance of a pixel in an on state and a pixel in an off state during multiplex driving of a conventional liquid crystal device.

21 is an xy chromaticity diagram in which the spectrum curve shown in FIG. 20 is plotted on color coordinates.

FIG. 22 is a diagram showing a structure of a liquid crystal device in one embodiment of the present invention.

FIG. 23 is a diagram showing a relationship between axes of the liquid crystal device of the present invention.

FIG. 24 (a) shows the twist angle and Δ of the liquid crystal of the A cell when the condition of the B cell is fixed in Example 1 of the present invention.
The figure which showed the desirable range of n * d. (B) is a figure which shows the relationship of (Y) value with respect to (DELTA) n * d when deriving the range of (a) by calculation.

FIG. 25 is a diagram showing the relationship between the wavelength and the transmittance characteristic of the appearance of the liquid crystal device of Example 2 of the present invention.

FIG. 26 is a diagram showing the relationship between the wavelength and the transmittance characteristic of the appearance of the liquid crystal device of Example 3 of the present invention.

FIG. 27 is a diagram showing the relationship between the wavelength and the transmittance characteristic of the appearance of the liquid crystal device of Example 4 of the present invention.

FIG. 28 is a diagram showing a desirable range of the twist angle and Δn · d of the liquid crystal of the A cell when the condition of the B cell is fixed in the example of the present invention.

FIG. 29 is a diagram showing the relationship between the wavelength and the transmittance characteristic of the appearance of the liquid crystal device of Example 6 of the present invention.

FIG. 30 is a diagram showing a desirable range of the twist angle and Δn · d of the liquid crystal of the A cell when the conditions of the B cell are fixed in Example 9 of the present invention.

FIG. 31 is a twist angle and Δn · d of the liquid crystal of the A cell when the conditions of the B cell are fixed in Example 10 of the present invention.
The figure which showed the desirable range of.

FIG. 32 is a twist angle and Δn · d of the liquid crystal of the A cell when the conditions of the B cell are fixed in Example 11 of the present invention.
The figure which showed the desirable range of.

FIG. 33 shows the twist angle and Δn · d of the liquid crystal of the A cell when the conditions of the B cell are fixed in Example 12 of the present invention.
The figure which showed the desirable range of.

FIG. 34 is a view showing the structure of the liquid crystal device of Embodiment 14 of the present invention.

FIG. 35 is a view showing the structure of the liquid crystal device of Example 20 of the present invention.

FIG. 36 is a diagram showing a relationship between axes 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 of 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 of each axis of the liquid crystal device of Example 31 of the present invention.

[Explanation of symbols]

 11, 18, 3861, 3867 Polarizing plate 12, 3863 Liquid crystal cell 19, 3862 Optical anisotropic body

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[Procedure amendment]

[Submission date] April 7, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

[0015]

Means for Solving the Problems] The liquid crystal device of the present invention, pairs
Liquid twisted and oriented more than 120 degrees between a pair of facing substrates
A liquid crystal cell sandwiching a crystal and at least one optical layer
An anisotropic body is arranged between a pair of polarizing plates,
The direction of the optical axis of the surface facing the liquid crystal cell of the anisotropic body,
Substrate on the side where the optically anisotropic body of the liquid crystal cell is arranged
The angle with the rubbing direction applied to the
The optically anisotropic substance is reflected by the light incident on the liquid crystal cell.
In contrast, the reverse conversion of the optical conversion performed by the liquid crystal cell is completely
Characterized by having properties that can be achieved over all wavelengths
I do.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Nagata 3-3-5 Yamato, Suwa, Nagano Seiko Epson Corporation (72) Inventor Kazuo Aoki 3-3-5 Yamato, Suwa, Nagano Prefecture Seiko Epson Within the corporation

Claims (1)

[Claims] 1. A liquid crystal cell in which a nematic liquid crystal twisted and oriented at 120 ° or more is sandwiched between a pair of substrates having electrodes formed on opposing inner surfaces, and at least one liquid crystal which is an optically anisotropic body. Having a polar polymer film in a pair of polarizing plates, and light incident on one of the polarizing plates is at each wavelength between the liquid crystal cell and the liquid crystal polymer film adjacent to the liquid crystal cell. The liquid crystal polymer film is arranged so that elliptically polarized light having different major axis directions becomes elliptically polarized light and then enters the other polarizing plate to become elliptically polarized light having substantially uniform major axis direction for each wavelength. Characteristic liquid crystal device.