JPH0228618A - Liquid crystal display element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field] The present invention has a liquid crystal layer sandwiched between substrates, and a polarizing means disposed outside the liquid crystal layer, so that the liquid crystal is polarized with respect to the substrates when no voltage is applied. 12 in the thickness direction of the liquid crystal layer.
The present invention relates to a liquid crystal display element having a twisted structure of 0° or more and 360° or less.

[Prior art and its problems]

The display mode of liquid crystals that has been mainly used in the past is called the twisted nematic (TN) type, in which the liquid crystal molecules are twisted approximately 90 degrees between a pair of upper and lower substrates, and the rotation of the plane of polarization by the liquid crystal is called the twisted nematic (TN) type. This method takes advantage of the fact that the effect disappears when voltage is applied. This display mode was sufficient for low time division driving such as watches and calculators, but when high time division driving was used to increase the display capacity, the contrast deteriorated and the viewing angle became narrower. There were drawbacks. This is because with high time division driving, the ratio of voltages applied to selected points and non-selected points approaches 1, and in order to obtain a display element with high contrast and a wide viewing angle, the relative transmittance of the element must be 10
% changing voltage v1. Voltage that changes by 50% against ■5
It is necessary to make the steepness γ, expressed as the ratio (VS./V1°), as small as possible.

In the case of twisted nematic type, this γ value is 1.13
That's about it. In order to reduce this γ value, a method has been proposed in which the twist angle of the liquid crystal molecules is increased and the polarization axis is shifted from the liquid crystal orientation direction, and these methods are called SBE mode or STN mode. According to such a system, the γ value can be reduced to 1.1 or less, and high time-division driving of about 1/400 duty is possible.

However, since this type of system uses coloring due to birefringence and its change due to voltage, it is difficult in principle to display black and white, and the transmitted light or reflected light of the liquid crystal cell is colored. In order to eliminate this kind of coloring that appears on the background, it is also known to overlap the STN type liquid crystal cell with another achromatic liquid crystal cell in which the twist direction of the liquid crystal molecules is opposite. . However, in this case, since two liquid crystal cells are stacked, the cost is high, and
The overall thickness and weight increase, and the distance between the polarizing plate and the display liquid crystal layer also increases, resulting in disadvantages such as a floating feeling in the displayed characters.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks of conventional liquid crystal display elements, and to provide a liquid crystal display element that is thin, lightweight, and capable of displaying black and white images with excellent display quality.

[Means for solving problems]

The present inventors have completed one of the present inventions as a result of extensive research in order to achieve the above object.

That is, according to one aspect of the present invention, a liquid crystal layer sandwiched between substrates;
comprising polarizing means disposed outside the liquid crystal layer, the liquid crystal comprising:
In a liquid crystal display element that is oriented substantially horizontally to the substrate when no voltage is applied and has a twisted structure of 120 @ or more and 360 @ or less in the thickness direction of the liquid crystal layer, between the liquid crystal layer and at least one polarizing means. , a medium layer having birefringence,
The birefringent medium layer is arranged so that the maximum refractive index direction in a plane parallel to the substrate forms an angle in the range of 20° to 70° with respect to the polarized light transmission axis of the polarizing means. A liquid crystal display element is provided.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view showing an example of the structure of a conventional liquid crystal display element. In this figure, 1 is a first substrate, and 11 is a second substrate, and each of the substrates 1 and 11 has alignment films 3 and 13 that have been subjected to alignment treatment and transparent electrodes 4 and 14.

Both substrates 1 and 11 are arranged facing each other and separated from each other, and a liquid crystal 6 is sealed between them to form a liquid crystal cell. 5
indicates a sealant. This liquid crystal cell is sandwiched between a first polarizing means 2 and a second polarizing means 12 to constitute a liquid crystal display element.

FIG. 2 is a cross-sectional view showing an example of the structure of the liquid crystal display element of the present invention, which differs from that in FIG. 1 in that a birefringent medium 7 is disposed between the substrate 1 and the polarizing means 2. are doing. This liquid crystal display element can also be used as a reflective type by disposing a reflecting plate on the outside of one of the polarizing means.

First substrate 1 and second substrate 11 of the liquid crystal display element of the present invention
The alignment treatment in is performed so that the liquid crystal molecules are aligned substantially horizontally when no voltage is applied, and the liquid crystal molecules are preferentially aligned along this alignment treatment direction. in this case.

The term "substantially horizontal" in terms of orientation of liquid crystal molecules means that the angle of inclination of the liquid crystal molecules with respect to the substrate is approximately in the range of 0 to 30 degrees.

FIG. 3 shows the definition of angles related to the present invention. Direction D4 for preferential alignment of liquid crystal molecules on the first substrate 1
, and the preferential alignment processing direction D3 on the second substrate 11, the liquid crystal molecules have a twisted structure by ω1. In this way, ω□ is the twist angle determined by the orientation process,
This orientation control can be performed by conventionally known oblique vapor deposition or by forming an inorganic or organic film and then rubbing it with a cotton cloth or the like. In the present invention, it is preferable to use a liquid crystal obtained by adding cholesteric liquid crystal or chiral nematic liquid crystal to a nematic liquid crystal having positive dielectric anisotropy and adjusting the pitch to an appropriate pitch. In this case, if ω1 is small, the steepness will worsen and the time-division drive characteristics will deteriorate, and if ω□ is too large, scattering structure will occur when an electric field is applied, which will deteriorate the display quality, which is undesirable. , From this, ω1 needs to be 120'' or more and 360° or less.

In Figure 3, when the cell is viewed from the first substrate side, the second
However, the twist direction is clockwise from the first substrate (lower substrate) to the first substrate (upper substrate).

Clockwise rotation can also be achieved depending on the direction of alignment treatment and selection of cholesteric liquid crystal or chiral nematic liquid crystal.

When a birefringent medium layer is provided between the substrate and the polarizing means as in the configuration example of the liquid crystal display element of the present invention, the substrates 1, 1
As material 1, transparent glass, plastic, or the like is used. When a plastic substrate is used, it is easy to reduce the thickness of the substrate to 0.2 mm or less, and therefore the display element can be configured to be extremely thin and lightweight. Furthermore, since the substrate is thin, the display does not display double images, and a display element with a wide viewing angle can be obtained.

Furthermore, as another example of the structure of the liquid crystal display element of the present invention, the substrate itself can also serve as a birefringent medium. in this case,
The layer structure of the device is the same as that of the conventional STN type liquid crystal display device shown in FIG. 1, except that at least one of the substrates 1 and 11 has birefringence.

This substrate that also serves as a birefringent medium may be composed of a single birefringent material, or may be laminated with other films, glass, or the like.

As yet another example of the structure of the liquid crystal display element of the present invention, the birefringent medium can be incorporated as a component of the polarizing plate itself. In the commonly used polarizing means that utilizes the dichroism of iodine and pigments, a stretched film is made to have polarizing ability by adsorbing iodine and pigments, and then the stretched film is sandwiched between two other films to protect it. However, the birefringent medium can be placed between the stretched film and the protective film on the liquid crystal layer side of the stretched film that has essential polarization performance, or the birefringent medium can be placed between the stretched film and the protective film on the liquid crystal side. can be composed of a refractive medium.

As described above, the birefringent medium used in the present invention may be placed anywhere between the liquid crystal layer and the polarizing means.

The birefringent medium referred to here has refractive index anisotropy in one plane and must have light transmission properties. Specifically, polyester, polycarbonate, polyarylate, polyetheretherketone, polysulfone,
Aromatic polymers such as polyether sulfone, polyolefin polymers such as polyethylene and polypropylene,
Examples include stretched or extruded films of vinyl polymers such as vinylidene chloride, polyvinyl alcohol, polystyrene, and acrylic resins, cellulose and its derivatives, such as regenerated cellulose (cellophane), diacetyl cellulose, and triacetyl cellulose. can. Alternatively, a thin piece of crystal such as mica, calcite, or quartz cut out along a plane parallel to the optical axis can also be used. Polymer-based materials can be particularly advantageously used in that large-area materials can be easily obtained.

The refractive index anisotropy Δn(BM) of a birefringent medium is the refractive index for polarized light parallel to the maximum refractive index direction (principal refractive index direction) in a plane parallel to the substrate of these media, and the refractive index for polarized light orthogonal to the maximum refractive index direction (principal refractive index direction) of these media. It is defined as the difference between

The optical axis of the birefringent medium needs to be tilted with the polarization axis of the adjacent polarization means, ie held at an angle other than parallel and orthogonal. If the principal refractive index direction of the birefringent medium is parallel or perpendicular to the polarization axis of the polarizing means,
The effect of the present invention is not achieved at all, and the display ends up being displayed on a colored background.

The preferred range of the angle of inclination (absolute value of angle B1 in FIG. 3) between the optical axis of the birefringent medium and the polarized light transmission axis of the polarizing means is as follows:
20@~70''.

As shown in FIG. 3, the transmission axis P2 of the polarizing means 12 adjacent to the second substrate 11 forms an angle β2 with the orientation direction of the liquid crystal on the second substrate 11, and the birefringent medium 7 is the liquid crystal alignment direction D1 on the adjacent substrate 11 whose main refractive index direction B (direction with the largest refractive index in the film plane)
and has an angle of δ. Further, the transmission axis P of the polarizing means 2 adjacent to the birefringent medium 7 and the principal refractive index direction B of the birefringent medium 7 are arranged to form an angle of β1. Note that the angle assumes that the direction of twist of the liquid crystal is positive.

Although FIG. 3 has been explained using the transmission axis of the polarizing means, it is completely equivalent to replace all of these with the absorption axis of the polarizing means.

In the STN type liquid crystal display element according to the present invention, when light passes through the liquid crystal layer, it becomes elliptically polarized light having an ellipticity and an azimuth of the ellipse that differ depending on the wavelength.The principle of the present invention is that the birefringent medium layer , by returning this to linearly polarized light or elliptically polarized light close to linearly polarized light and passing it through a polarizing means arranged parallel to or at right angles to the linearly polarized light.
The background color when no voltage is applied is obtained, which is white or black, respectively. In addition, it is actually colorless and transparent, not white, but 1
For convenience, we will refer to this as white in order to express the zero-line principle and obtain a display element that is capable of black-and-white display, has excellent display quality, and has little single-color unevenness. There are particularly preferred ranges for the

The first preferred range is that the absolute value of β2 is 20-70
It is specified in relation to the range of ゜.

Table 1 shows that the twist angle ω□ is 200°, β, =45
@, β1 = 45°, the product of the refractive index anisotropy Δn (LC) of the liquid crystal and the thickness d (LC) of the liquid crystal layer is 0.90 pm, and the refractive index anisotropy Δn (BM) of the birefringent medium and Film thickness d (BM)
Taking as an example the case where the product Δn(BM)d(BM) is 0°83-, the contrast during operation and δ (the angle formed by the maximum refractive index direction B of the birefringent medium and the liquid crystal orientation direction D1 in the substrate 1) ). As a polarizing plate, an iodine type neutral gray polarizing plate was used (
Same below).

As the angle of δ in Table 1 increases from 45° to 1456,
The color of the cell changed from very pale blue to very pale green to very pale yellow, and a pale white background could be obtained.

From these facts, it is necessary that δ be in the range of 60° to 120° in order to obtain high contrast.

A range of 70° to 110° is more preferable, and the above tendency holds true even when the twist angle ω□, Δnd of the liquid crystal layer and Δnd of the birefringent medium, etc. are changed.

Generally, light passing through a medium having optical anisotropy produces a phase difference between the ordinary ray and the extraordinary ray.

In the present invention, it is important to match the retardations of the liquid crystal layer and the birefringent medium in order to obtain black and white and high contrast. In this case, the retardation RBM (unit: niradian) of the birefringent medium is defined by the following equation.

(In the formula, Δn(BM) is the refractive index anisotropy of the birefringent medium.

d(BM) is the thickness of the birefringent medium, and λ is the wavelength of light.) The retardation RLe of the liquid crystal layer is defined by the following formula.

(In the formula, Δn(LC) is the refractive index anisotropy of the liquid crystal, d (L
C) is the thickness of the liquid crystal layer, λ is the wavelength of light, and ω1 is the twist angle of the liquid crystal molecules between the substrates (unit: niradian). Note that the wavelength λ of light mentioned above is usually represented by 550 nm. I can do it.

In the present invention, the first In a cell under the same conditions as in the table (however, δ = 90°), the Δnd of the liquid crystal layer
Table 2 shows the color change of the cell when changing (Re
= 1.51π).

As can be seen from Table 2, flt, c is approximately 0 from RBM.
．． If it is about 8π larger than RBM, coloring becomes large when no voltage is applied, which is undesirable.
If it is smaller than 15c, coloring will become noticeable, which is not preferable.

In the end, it is preferable that the RLC-RBM is in the range of 10.15π-+0.75π.

Furthermore, considering the range in which high contrast can be obtained, RLC-RBM can be set from -0.15π to +0.15
A range of π or 100.22π to +〇, 75π is more preferable; in the former case, the color becomes black when no voltage is applied, and in the latter case, the color becomes white when no voltage is applied. In these cases Δn(B
M) d(BM) is 0.5- or more, 2I! By setting it to m or less, a display element with higher contrast can be obtained.

Moreover, as another preferable range, Δn (BM)d (
BM) is 0.2 or more and 0.5- or less, F
An example of this is increasing ILc with respect to RBM within a range of 0.82π or more and 1.1π or less. Δn(BM)
d(BM) is 0.5 to 0.2. As in the case of , in this case as well, if it is outside the above range, coloring or contrast will decrease. Further, when both β1 and β2 are positive, in this case, the color becomes black when no voltage is applied.

Although the case where both β and β2 are positive has been described above, the case where both β and β2 are negative is exactly the same.

Also, if the signs of β and β2 are opposite, black and white are inverted.

The liquid crystal display element of the present invention, as illustrated in FIG.
It is white or black when no voltage is applied, and becomes black or white when voltage is applied. Incidentally, FIG. 5 illustrates the transmission spectrum of a conventional STN type liquid crystal display element for comparison.

A second preferable range of the angular relationship and the retardage J between the liquid crystal layer and the birefringent medium layer is defined in relation to the absolute value of β2 in the range of 00 to 25°. In this range of β2, δ needs to be in the range of 20° to 130°. Table 3 shows Δn(BM)d(88 households 0.413., Δ
n(LC)d(LC)=0.54/4, ω1=200
2 shows the color of the cell when no voltage is applied and the contrast during operation in the case of @, β2 = 0°, β1 = 45°.

Table 3 As shown in Table 3.

δ ranges from 20° to 130° The contrast increases and each color approaches black.

A more preferable range of δ is 40° to 110@. At this time, the cell becomes white due to voltage application, and good black-and-white contrast can be obtained. In order to obtain a good black and white display, it is further necessary to set the retardation (Raw) of the birefringent medium in the range of 0.125π to π (radian). This is Δn(BM)d(BM)
This is converted into a range of 0.07 JR - 0.55 pm.

If it is outside this range, the Δnd of the liquid crystal that becomes white or black when no voltage is applied will not exist, resulting in a colored background or extremely low contrast.e A more preferable range for RBH is 0.55π to 0.94π. , converted to Δnd, Δn(BM)d(BM)=0.3(1-0,52m
It is.

A liquid crystal display element that satisfies the conditions shown above.

It is black when no voltage is applied, and becomes white (colorless and transparent) when voltage is applied.

Also, for the same reason, the retardation (R) of the liquid crystal layer
LC) is preferably approximately 1.5π or 2π radians, Table 4 shows that Δn(BM)d(ON)=0.4
31R1ω□=200", β2=0°, β,=45°,
The color of the cell is shown when δ=90°. Examples of preferred ranges include 1.35π to 1.7π or 1.8π to 2.

In Table 4 and above, the case where the twist angle ω is 200° has been explained as an example, but the same applies to other twist angles.

The same applies even if the birefringent medium is integrated with the substrate or polarizing plate.

As described above, by selecting the retardation of the liquid crystal and the birefringent medium within the above range, the background color of the element can be set to white or black, and when voltage is applied, the background color can be set to black, dark blue, or white, respectively. This enables black and white display. In addition, other than providing birefringence to the substrate and interposing a birefringent medium between the liquid crystal layer and the first polarizing means, the structure of the device is exactly the same as that of conventional liquid crystal display devices, so production is easy. is extremely easy. Furthermore, since the spectral transmittance in the visible light range is almost flat, there is no light leakage due to wavelength, and it can also be applied to light shutters for color displays.

In the above description, one birefringent medium is used, but a plurality of birefringent media may be used. In this case, the birefringent medium may be disposed only on one side of the liquid crystal layer, or may be disposed on both sides.Also, when a cell is constructed using two birefringent media, both light As mentioned above, the axis may be tilted with respect to the polarization axis of the adjacent polarization means, or only one of them may be tilted, and in the latter case, the birefringence is arranged parallel to or perpendicular to the polarization axis. The medium thickness is not limited, and a birefringent medium having a retardation of 1 Opa or more can also be used.

Next, d(BM) and Δn of the birefringent medium used in the present invention
A specific value of (BM)·d(BM) will be illustrated.

Table 5 Since these polymer films have flexibility, they can be easily laminated by forming an adhesive layer on their surface, and the cell itself can be used as a plastic substrate liquid crystal with flexibility. It is also easy to paste onto the surface of the cell. Moreover, since the polymer material is extremely cheap,
Increase in cost can also be reduced.

〔effect〕

According to the present invention, it is possible to easily solve the problem of coloring, which is a drawback of an STN type liquid crystal display element, and to obtain a monochrome display liquid crystal display element with excellent display quality.

Unlike conventional products that use liquid crystal elements, the liquid crystal display element of the present invention uses a birefringent medium as a compensating plate for achromatization, so the increase in thickness and weight can be minimized, and it can be manufactured at low cost. It is possible.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 It has a transparent electrode, the twist angle of the liquid crystal between the upper and lower glass substrates is 200 degrees, and Δn(LC)・d(L(:) is 0,
A liquid crystal cell of 92IIm (RLc=2.0πrad) was fabricated. In this case, the liquid crystal used was a nematic liquid crystal ZLI2293 having positive dielectric anisotropy to which chiral nematic liquid crystal 3811 was added. The alignment treatment for this liquid crystal was performed by rubbing the polyimide film. At the bottom of this cell, a neutral gray polarizing plate with a reflector was placed so that its transmission axis made an angle of 45 degrees with the rubbing direction of the lower substrate (β2 = 45@).
On the upper substrate, 50. polypropylene stretched film with a thickness of (RBH=1.52πrad, Δn(BM)・d(
BM) = 0.8344) is arranged so that its principal refractive index direction and the rubbing direction of the upper substrate are orthogonal to δ = 90°.
), and a polarizing plate was placed thereon so that its transmission axis made an angle of 145 degrees (β1=45°) with the direction of the principal refractive index of the film (Rt, c-Rgx=0-48 x ra
d).

The liquid crystal display element configured as described above was black when no voltage was applied, turned white when voltage was applied, and was capable of black-and-white display.

Further, the steepness γ of the voltage-transmittance characteristic was 1.03 or less, and the device had excellent time-division drive characteristics.

In this display element, black and white were reversed by rotating the upper or lower polarizing plate by 90 degrees. When the film is rotated horizontally on the substrate while keeping the angle β□ between the transmission axis of the upper polarizing plate and the principal refractive index direction of the film constant at 45°, the principal refractive index direction of the film and the upper substrate side rubbing Angle δ between directions
Good contrast was exhibited in the range of 60° to 120°, whereas the contrast decreased in other angles.

Example 2 In Example 1, Δn(LC)・d(LC) of the liquid crystal layer
A cell was similarly prepared with only 0.64 (RLc=1.56πrad) (RLc-hx”o, 04 tc
rad) *The liquid crystal display element configured in this manner was white when no voltage was applied, and turned black when voltage was applied.

Example 3 In Example 1, Δn(LC)・d(LC) of the liquid crystal layer
kc: 1.56 x rad), Δn(BM)d(BM)=0.34pm as a birefringent medium
(Rax=0.62 πrad) to make a cell using cellophane with a thickness of 4011 m.Rt, c-ReM=0
．． 94πrad), and the upper polarizing plate was placed at a position of β1=45°.

This liquid crystal display element was black when no voltage was applied, and turned white when voltage was applied.

Example 4 Similar to Example 1, twist angle ω1180°, Δn
(LC)・d(LC) is 0.72. A liquid crystal cell was prepared (R1, c=1.72 x rad) m.A lower polarizing plate was placed on this liquid crystal cell so that the polarizing plate angle β2=45°. At the top of the cell, Δn(BM)・
d(BM)=0.63pm(RBM=1.15πrad
) was placed such that the principal refractive index direction was perpendicular to the rubbing direction of the upper substrate. The polarization axis of the upper polarizing plate was arranged at -45° or 45°. With each polarizing plate arrangement, this element was black and white when no voltage was applied. When voltage is applied,
They became white and black, respectively.

Example 5 Similar to Example 1, twist angle ω1 is 240°, Δ
A liquid crystal cell with n(LC)・d(LC) of 1.04 was fabricated (Rt, c=2.25 tc rad) aFor this liquid crystal cell, Δn(BM)・d (BM)−0, 9
A display element was constructed in the same manner using a polypropylene film of 47s (RBM: 1, 71 pc rad) as a birefringent medium (β2=45°, δ=90
°, β1 = 45°).

This liquid crystal display element was also capable of black-and-white display, and exhibited extremely excellent time-division drive characteristics with a steepness of 1.02.

Example 6 As a liquid crystal composition, chiral nematic liquid crystal (manufactured by Merck & Co., Ltd., 5
A liquid crystal composition containing 0.5% of 811) was used. Apply polyimide to the glass substrate, rub it, and twist angle 1
The upper and lower substrates were attached at an angle of 80°, and the liquid crystal composition was filled therein. The thickness of the liquid crystal layer is 5.2 tones (Δn(LC)・d(LC)=0.61s, RLc=
1.487 Crad).

The lower polarizing plate was arranged so that the polarizing plate angle was β2:0 +1. At the top of the cell, Δn(BM)・d(BN
)=0.41p(RB)4=0.78μs) are laminated so that their principal refractive index direction forms an angle of 70° with the rubbing direction of the upper substrate, and a polarizing plate is further placed on top of the cellophane film with β1 =45°.

This element turned almost completely black when no voltage was applied, and turned white when voltage was applied.

Note that if the film is rotated horizontally on the substrate while keeping β at 45°, it becomes almost black in the range of δ from 20' to 130°, and good contrast can be obtained with voltage application, whereas other So I colored it purple.

Example 7 Similar to Example 6, Δn(LC)・d(LC)=-
0,534 (RL0=1.4πrad) liquid crystal cell was produced. The lower polarizing plate was arranged so that β2=0°. On top of this, Δn (ON) ・d (BM) = 0.14m
(Ras = 0.25 x rad) triacetyl cellulose films are laminated such that their principal refractive index direction forms an angle of 90' with the rubbing direction of the upper substrate,
Next, the upper polarizing plate was arranged so that β1=45'.

This element displayed almost black color when no voltage was applied, and displayed white color when voltage was applied.

Example 8 A liquid crystal cell was produced in the same manner as in Example 1 except that a polyether sulfone plastic film was used as the substrate. Like the glass substrate, this device was also capable of black-and-white display, exhibited excellent time-division drive characteristics, and exhibited excellent display quality with no double images and a wide viewing angle.

Example 9 A triacetyl cellulose film having a transparent electrode and Δnd of 0.6- was subjected to horizontal alignment treatment by a rubbing method in the 90@ direction with respect to its optical axis (substrate 2).
Further, a similar substrate was subjected to horizontal alignment treatment by rubbing in a direction of 45° with respect to the optical axis (substrate 1). Next, open the board (
1) and (2) were glued together so that the twist angle was 200°. The distance between the upper and lower boards was set to 7 voices using spacers. Δn=0.10 ps between the upper and lower substrates, filled with nematic liquid crystal with positive dielectric anisotropy doped with chiral nematic liquid crystal S-811,
A pair of polarizing plates was placed on the outside of the substrate. Here board 2
The side polarizing plate was arranged so that its transmission axis formed an angle of 45° with the rubbing direction, with the direction of twist from the substrate 2 toward the substrate being positive. Note that the optical axis of the substrate 1 and the transmission axis of the polarizing plate were parallel to each other.

With the above configuration, Δn(LC)・d(LC)=0.7m
, Δn(Bs)-d(uM)=o, 611m, β1=4
A liquid crystal display element of the present invention was obtained, in which the liquid crystal display element had the following properties: 5", β = 45", and δ = 900.

This element was white (colorless) when no voltage was applied, and could display black when voltage was applied. Also.

The steepness was 1.04, which was extremely excellent. Also, rotate the polarizing plate on the first substrate side by 90° (β1 = 45')
This resulted in a black-white inverted display.

Example 10 A liquid crystal display element with a twist angle of 200'' was produced in the same manner as in Example 9, using a glass plate laminated with a stretched film of regenerated cellulose as the substrate 2 and a glass plate as the substrate 1 ( Δn(LC)・d(LC)=
0.7IIm, Δn(BM)・d(BM)=0.6ps
, β, = 45'', β1 = 45', δ = 90''), this device was also capable of black-and-white display and exhibited excellent time-division drive characteristics.

Example 11 Similarly to Example IO, Δn(LC)・d(LC)=
0.64, Δn(BM)・d(BM) =0.41m,
A liquid crystal display element was prepared in which β, = 0@, β1 = 45', and δ = 60', and this element was also capable of black and white display and exhibited excellent time-division drive characteristics.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of the configuration of a conventional liquid crystal display element. FIG. 2 shows a cross-sectional view of a configuration example of a liquid crystal display element of the present invention. FIG. 3 is an explanatory diagram of the angular relationship between the liquid crystal alignment direction, polarization axis direction, etc. of the liquid crystal display element of the present invention. FIG. 4 is a graph showing the relationship between wavelength (nm) and light transmittance (%) of the liquid crystal display element of the present invention. FIG. 5 is a graph showing the relationship between wavelength (nm) and light transmittance (%) of a conventional liquid crystal display element. 1.11...Substrate, 2.12...Linear polarization means,
3.13...Alignment film, 4,14...Transparent electrode, 5.
... Seal material, 6... Liquid crystal, 7... Birefringent medium,
Dl...Alignment direction of liquid crystal on the first substrate, D2...Alignment direction of liquid crystal on the second substrate. P, . . . polarization axis direction of the polarization means on the first substrate side, P2.
...Polarization axis direction of the polarization means on the second substrate side. Patent Applicant: Rico Co., Ltd. Patent Attorney: Toshiaki Ikeura (and 1 other person) Figure 2 Figure 4 Figure 5

Claims (5)

[Claims] (1) It has a liquid crystal layer sandwiched between substrates and a polarizing means placed outside the liquid crystal layer, and the liquid crystal is oriented approximately horizontally to the substrate when no voltage is applied, and in the thickness direction of the liquid crystal layer. 120 to
In a liquid crystal display element having a twisted structure of at least 360 degrees, a birefringent medium layer is provided between the liquid crystal layer and at least one polarizing means, parallel to the substrate of the birefringent medium layer. 1. A liquid crystal display device, characterized in that the direction of the maximum refractive index in the plane forms an angle in the range of 20° to 70° with respect to the polarized light transmission axis of the polarizing means. (2) The liquid crystal alignment direction on the substrate surface adjacent to the polarizing means is
20° to the polarization transmission axis or absorption axis of the polarizing means
forming an angle in the range of 70°, and the maximum refractive index direction of the birefringent medium and the liquid crystal orientation direction on the substrate surface adjacent to the birefringent medium forming an angle in the range of 60° to 120°,
Either make the retardation (R_L_C) of the liquid crystal layer almost equal to the retardation (R_B_M) of the birefringent medium, or make R_L_C 0.75π (ra) smaller than R_B_M.
d) Increase within the range below or 0.82π(ra
2. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is increased in a range from d) to 1.1π (rad). (3) The liquid crystal alignment direction on the substrate surface adjacent to the polarizing means is
0° to 2 with respect to the polarization transmission axis or absorption axis of the polarizing means
forming an angle in the range of 5°, and the maximum refractive index direction of the birefringent medium and the liquid crystal alignment direction on the substrate surface adjacent to the birefringent medium forming an angle in the range of 20° to 130°,
The retardation (R_B_M) of the birefringent medium is 0.1
The range is 25π (rad) to π (rad), and the retardation (R_L_C) of the liquid crystal layer is approximately 3/2π (
2. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is set to 2π (rad) or 2π (rad). (4) The liquid crystal according to any one of claims 1 to 3, wherein the liquid crystal layer is formed between transparent substrates, and the birefringent medium is formed between the polarizing means and the substrate. display element. (5) The liquid crystal display element according to any one of claims 1 to 3, wherein the liquid crystal layer is formed between transparent substrates, and at least one of the substrates also serves as a birefringent medium.