JP2000162574A - Liquid crystal display element and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a GH mode liquid crystal display element which is able to be driven with a low voltage and has high contrast. SOLUTION: To a liquid crystal layer 20 having hybrid alignment, formed by providing a high pretilt alignment layer 5 which makes a liquid crystal 7a align in a direction almost normal to a first substrate 1 and a homogeneous alignment layer 6 which makes a liquid crystal 7b align in parallel to a second substrate 2, furthermore a chiral dopant is added so as to form the alignment of the liquid crystals 7... as a twisted structure. Thereby a GH mode liquid crystal display element is obtained which can be driven with a low driving voltage and yet can display with high contrast.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element used for a display device using a liquid crystal.

[0002]

2. Description of the Related Art Conventionally, guests using a dichroic dye
Some host (GH) type liquid crystal display elements use only one polarizing plate, and others display an image without using a polarizing plate. A reflection type liquid crystal display is used because light can be used effectively. It is considered suitable for the device.

The GH mode using one polarizing plate includes:
Heilmeier type liquid crystal display element. For example, as shown in FIG. 19, the Heilmeier-type liquid crystal display element includes a pixel electrode 114 or a counter electrode 11.
3, and the substrate 111 on which the alignment films 115 and 116 are formed
Liquid crystal 120 ... and dichroic dye 121 ... between 112
And a liquid crystal layer 117 composed of Further, a polarizing plate 122 is provided on the outer surface of the substrate 111.

Here, an operation mode for driving the Heilmeier type liquid crystal display device will be described. First, when no electric field is applied to the liquid crystal layer 117, the liquid crystal 120
And the dichroic dyes 121 are in the homogeneous alignment state, and their alignment directions are parallel to the polarization axis of the polarizing plate 122. The dichroic dye 121 is also affected by the liquid crystal 120 and is oriented in the same direction as the liquid crystal 120. Therefore, the light absorption axis of the dichroic dye 121 is parallel to the polarization direction of the light, and the dichroic dye 121 is in an absorption mode in which light is absorbed. As a result, the display screen is in a dark state. On the other hand, when an electric field is applied, the liquid crystal 120 a near the center of the liquid crystal layer 117 is oriented in the vertical direction on the substrate 111. The dichroic dye 121 a also changes its alignment direction following the change in the alignment of the liquid crystal 120... And becomes perpendicular to the substrate 111. Therefore, 2
Since the light absorption axis of the chromatic dye 121a is also oriented in the direction perpendicular to the substrate 111, the absorption of light of the dichroic dye 121a is reduced, and most of the light is transmitted. As a result, the display screen is in a bright state. However, the alignment film 115.1.
The liquid crystals 120 b near the liquid crystal 120 near the alignment film 115
The initial alignment state is maintained because it is bound by the alignment regulating force of 116. Further, the alignment film 115.1.
The dichroic dyes 121b and 121b in the vicinity of 16 also maintain the initial alignment state. Therefore, the alignment films 115 and 11
The dichroic dyes 121b and 121b in the vicinity of 6 are in the light absorption mode, and some transmittance is impaired. Moreover,
Since the polarizing plate 122 is provided, the transmittance is further reduced.
Therefore, the Heilmeier type GH mode using one polarizing plate has a problem that the contrast is low.

On the other hand, even in the GH mode without using a polarizing plate, there is still a display problem that the contrast is low. The reason is that the dichroic dye has only one light absorption axis, so that light that vibrates in all directions, such as natural light, cannot absorb light that vibrates in directions other than the light absorption axis. It is in. Therefore, in order to improve the contrast, a contrivance has been made to add a chiral agent. Thereby, the liquid crystal molecules and the dichroic dye are made isotropic as a twisted structure, so that light of any polarization can be absorbed. That is, the absorbance in all directions is increased. In this case, to prevent incident light from rotating along the twisted structure due to the refractive index anisotropy of each liquid crystal molecule, select a liquid crystal molecule having a small refractive index anisotropy and reduce the twist pitch. It is necessary to shorten it. However, there is a problem that when the ratio between the twist pitch p and the liquid crystal cell thickness d is increased (that is, when the twist pitch is reduced), the drive voltage is increased.

As a liquid crystal display device using a polarizing plate, there is a TN (twisted nematic) mode most widely used in addition to the above. This TN mode is
The liquid crystal has a twist angle of about 90 degrees and is applied to a liquid crystal panel driven by an active matrix using TFT elements or the like, or a liquid crystal panel driven by a simple matrix used for simple display such as a clock.

Further, in addition to the TN mode, a twist angle of 1
An STN (super twisted nematic) mode in which the angle is increased to about 80 to 260 degrees is also available (for example,
No. 0-107020). This STN mode is based on the T
By increasing the twist angle to about 180 degrees to 260 degrees compared to the N mode, the threshold characteristics are sharpened, and the number of scan lines that can be driven by simple matrix driving and the contrast are improved. As the material of the liquid crystal used in the STN mode, a liquid crystal having a small ratio K ₃ / K ₁ of the elastic constant K ₁ of the splay deformation and the elastic constant K ₃ of the bend deformation is selected. This is because as the K ₃ / K ₁ is smaller steepness increases (e.g.,艸林Seiwa ed., "Liquid crystal material", pp. 205, 1991).

However, the TN mode and STN mode liquid crystal display elements have the following problems. That is, in these liquid crystal display modes, the threshold characteristics are sharpened in order to increase the display capacity. However, if the threshold characteristics are sharpened, there is a problem that the drive voltage increases and the responsiveness decreases. are doing.

Further, in addition to the TN mode and the STN mode, a liquid crystal display device of a hybrid alignment mode in which liquid crystal near one substrate is horizontally aligned and liquid crystal near the other substrate is vertically aligned. Can be In this mode, it is known that since the orientation of the liquid crystal includes deformation even in the absence of an electric field, there is no threshold value, the driving voltage is low, and the response speed is high (for example, see Japanese Unexamined Patent Publication No. 160
890). In addition, since the hybrid alignment mode has no threshold value, an active element is required for driving. For example, as disclosed in JP-A-6-160890, there is shown an example in which a reflective liquid crystal display element is formed by combining with a photoconductor film and used for a light valve or by combining with a TFT element. I have.

Summarizing the above, the above-mentioned conventional liquid crystal display device has the following problems.

A conventional GH mode liquid crystal display device having a polarizing plate has a problem that the contrast is low. On the other hand, GH having a twisted structure without a polarizing plate
In the mode, the contrast could be improved,
There is a problem that the driving voltage is high due to the twist structure.

In a TN mode or STN mode liquid crystal display element, a steep threshold characteristic is intended to increase a display capacity. As a result, however, a drive voltage is increased and a response speed is reduced. Has problems.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems.
An object of the present invention is to provide a GH mode liquid crystal display device which can be driven at a low voltage and has high contrast.

A second object of the present invention is to provide a liquid crystal display element driven by a simple matrix in which the driving voltage is suppressed and the response is improved.

[0015]

According to a first aspect of the present invention, a liquid crystal layer including a liquid crystal is provided between a pair of opposed substrates. The liquid crystal in the vicinity of the inner surface of the first substrate is inclined and oriented with respect to the first substrate within a range of 30 degrees or more and 90 degrees or less with respect to the first substrate. A liquid crystal display having an alignment treatment performed on the inner surface of the second substrate of the substrate so as to align liquid crystal near the inner surface in a direction substantially parallel to the second substrate. The device is characterized in that the liquid crystal layer contains a dichroic dye and a chiral agent, and the liquid crystal in the liquid crystal layer has a twisted structure.

With the above configuration, a GH mode liquid crystal display device in which a twist structure is added to the conventional hybrid alignment mode can be obtained. Thereby, the following various effects can be obtained. First, the liquid crystal in the vicinity of the first substrate is oriented such that the pretilt angle with respect to the first substrate is in the range of 30 degrees or more and 90 degrees or less in the initial alignment state. Therefore, when a voltage is applied to align the liquid crystal in the normal direction of the first substrate, the liquid crystal closer to the first substrate is oriented at a higher tilt angle as described above. Can be changed to Therefore, it is possible to provide a liquid crystal display element that can be driven at a lower voltage than a GH mode liquid crystal display element having a conventional twisted structure.

Further, since the dichroic dye also has a twisted structure together with the liquid crystal, it absorbs not only light oscillating in a predetermined direction but also light oscillating in various directions such as natural light. Will be able to Therefore, the amount of light absorption of the dichroic dye when no voltage is applied can be increased, and the transmittance can be reduced.
The contrast can be improved as compared with a liquid crystal display device of a type GH mode or a hybrid alignment mode.
On the other hand, the liquid crystal in the vicinity of the first substrate is already aligned in the initial alignment state so that the pretilt angle is within the range of 30 to 90 degrees with respect to the first substrate. This alignment state is maintained by the influence of the alignment regulating force. Since the dichroic dye near the first substrate is also in the same alignment state as the liquid crystal, the light transmittance of the dichroic dye is not impaired. Therefore, it is possible to provide a liquid crystal display device having a high contrast even with a conventional GH mode liquid crystal display device having a twisted structure.

According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect, the twist angle of the liquid crystal is 180.
It is characterized by being within the range of not less than degrees and not more than 270 degrees.

As described above, the twist angle of the liquid crystal is set to 180.
By setting the temperature to not less than the degree, the light transmittance when no voltage is applied can be reduced. This is because the dichroic dye is twisted together with the liquid crystal, so that the dichroic dye can absorb light vibrating in various directions. On the other hand, by setting the twist angle of the liquid crystal to 270 degrees or less, the increase in the threshold voltage can be suppressed, and the occurrence of the hysteresis phenomenon can be prevented.

According to a third aspect of the present invention, in the liquid crystal display device according to the first or second aspect, the pretilt angle of the liquid crystal near the inner surface of the first substrate is 50 degrees or more and 70 degrees or more. It is characterized in the following range.

As described above, by setting the pretilt angle of the liquid crystal in the vicinity of the inner surface of the first substrate within the range of 50 to 70 degrees, good responsiveness can be maintained and low drive voltage can be maintained. High-contrast display can be performed.

According to a fourth aspect of the present invention, in the liquid crystal display device according to any one of the first, second, and third aspects, the liquid crystal near the inner surface of the second substrate is provided. Are oriented parallel to the second substrate, or are oriented such that the pretilt angle of the liquid crystal is in the range of more than 0 ° and 10 ° or less.

With the above configuration, the transmittance when no voltage is applied can be reduced. That is, the second
By aligning the liquid crystal near the substrate so that it is parallel to the second substrate or the pretilt angle of the liquid crystal is within a range of more than 0 degree and 10 degrees or less, the dichroic dye also follows the liquid crystal. Array. Thereby, the absorption of light by the dichroic dye can be increased, and the contrast can be improved.

According to a fifth aspect of the present invention, there is provided a liquid crystal display device according to any one of the first to fourth aspects, wherein:
The twist elastic constant K ₂ and the bending elastic constant K _{3 in the} above liquid crystal
The ratio K ₃ / K ₂ is one or more and, characterized in that in the range of 2.5 or less.

According to a sixth aspect of the present invention, there is provided a liquid crystal display device according to any one of the first to fifth aspects.
The liquid crystal is characterized in that the ratio K ₂ / K ₁ of the spreading elastic constant K ₁ and the torsional elastic constant K _{2 in the} liquid crystal is in the range of 1 or more and 3 or less.

According to the structure of the fifth and sixth aspects, the reflectance of light when no voltage is applied (dark state) can be suppressed. As a result, the contrast can be improved.

According to a seventh aspect of the present invention, in the liquid crystal display device according to any one of the first to sixth aspects,
A reflection plate is provided behind the liquid crystal layer.

With the above configuration, it is possible to provide a high-contrast reflective liquid crystal display device with a reduced driving voltage.

In order to solve the above-mentioned problem, the invention according to claim 8 is provided with an electrode on each inner surface, and a liquid crystal layer is provided between a first substrate and a second substrate which are arranged to face each other. In the above liquid crystal display device, the first liquid crystal layer is formed by interposing a first intermediate substrate and a second intermediate substrate spaced from each other between the first substrate and the second substrate. ~
The third liquid crystal layer has a three-layer structure.
A liquid crystal layer is provided between the first substrate and a first intermediate substrate facing the first substrate and having an electrode on one of the surfaces, and the second liquid crystal layer is provided on the first intermediate substrate. And a second intermediate substrate facing the first intermediate substrate and having an electrode on one of its surfaces, wherein the third liquid crystal layer is
A liquid crystal near the inner surface is provided on one inner surface of a substrate provided between the intermediate substrate and the second substrate and sandwiching each of the first to third liquid crystal layers. An alignment process is performed so that the pre-tilt angle is tilted within the range of 30 degrees or more and 90 degrees or less, and the other of the substrates sandwiching each of the first to third liquid crystal layers is formed. On the inner surface,
The liquid crystal near the other inner surface is subjected to an alignment treatment so as to be oriented in a direction substantially parallel to the substrate, and the first to third liquid crystal layers are selected from cyan, magenta, and yellow. It is characterized in that dichroic dyes of different colors are contained so as to be different from each other, a chiral agent is contained, and the liquid crystal in the first to third liquid crystal layers has a twisted structure.

According to the above configuration, in each liquid crystal layer, the initial alignment state of the liquid crystal originally near one substrate is set so that the pretilt angle with respect to the substrate is in the range of 30 to 90 degrees. It is oriented, and this initial orientation state is maintained by the influence of the alignment regulating force even when a voltage is applied. Since the dichroic dye near the one substrate is also in the same alignment state as the liquid crystal, the light transmittance is not impaired by the light absorption of the dichroic dye. As a result, it is possible to provide a full-color type liquid crystal display device with high utilization efficiency of incident light and high brightness with good color purity.

According to a ninth aspect of the present invention, in the liquid crystal display device according to the eighth aspect, the twist angle of the liquid crystal is 180.
It is characterized by being within the range of not less than degrees and not more than 270 degrees.

According to a tenth aspect of the present invention, in the liquid crystal display element according to the eighth or ninth aspect, the substrate sandwiching each of the first to third liquid crystal layers is arranged in a direction perpendicular to the substrate. The liquid crystal is characterized in that the pretilt angle of the liquid crystal in the vicinity of the inner side surface that has been subjected to the alignment treatment is in the range of 50 degrees or more and 70 degrees or less.

The functions and effects of the ninth and tenth aspects are substantially the same as those described in the second or third aspect. Therefore, claim 9 and claim 10
The detailed description of the operation and effect of the invention of the above is omitted.

In order to solve the above-mentioned problems, the invention according to claim 11 is provided with an electrode on each inner surface, and a liquid crystal layer containing liquid crystal is provided between a pair of substrates arranged opposite to each other. The liquid crystal near the inner surface of the first substrate is provided on the inner surface of the first substrate with a pretilt angle of 40 with respect to the first substrate.
Alignment treatment is performed so as to be tilted within the range of not less than 90 degrees and not more than 90 degrees. Similarly, on the inner surface of the second substrate, the liquid crystal near the inner surface is substantially parallel to the substrate. In a liquid crystal display element which has been subjected to an alignment treatment so as to be oriented in a direction, a polarizing plate is provided outside each of the pair of substrates, and the liquid crystal layer contains a chiral agent. The liquid crystal has a twisted structure.

According to the above configuration, since the polarizing plates are provided on the outer surfaces of the pair of substrates, respectively, a twisted structure is added to the conventional hybrid alignment mode, and a liquid crystal capable of displaying by the birefringence effect is provided. It can be a display element. Here, the liquid crystal in the vicinity of the first substrate is oriented such that its initial orientation state is within a range of a pretilt angle of 40 to 90 degrees with respect to the first substrate. Therefore, when a voltage is applied to align the liquid crystal in the normal direction of the first substrate, the liquid crystal closer to the first substrate is oriented at a higher tilt angle as described above. Can be easily transferred to In addition, the transition time from the initial alignment state to the new alignment state is short. Therefore, a liquid crystal display device which can be driven at a low voltage and has excellent responsiveness can be provided as compared with a conventional STN mode liquid crystal display device.

Further, by introducing a twist structure into the conventional hybrid alignment mode, a threshold value can be provided. As a result, driving by the simple matrix driving method becomes possible. When a voltage is applied, in the conventional STN mode liquid crystal display device, the liquid crystal is inclined in an oblique direction, whereas in the present invention, the liquid crystal is oriented in the normal direction of the first substrate. I have. Therefore, it is possible to provide a liquid crystal display device having a wide viewing angle with reduced dependency on the viewing angle.

According to a twelfth aspect of the present invention, a liquid crystal layer including a liquid crystal is provided between a pair of substrates disposed opposite to each other. The liquid crystal near the inner surface of the first substrate is provided on the inner surface of the first substrate with a pretilt angle of 40 with respect to the first substrate.
Alignment treatment is performed so as to be tilted within the range of not less than 90 degrees and not more than 90 degrees. Similarly, on the inner surface of the second substrate, the liquid crystal near the inner surface is substantially parallel to the substrate. In a liquid crystal display element that has been subjected to an alignment treatment so as to orient in a direction, a polarizing plate is provided in front of the liquid crystal layer,
In addition, a reflector is provided behind the liquid crystal layer, and the liquid crystal layer further contains a chiral agent, and the liquid crystal in the liquid crystal layer has a twisted structure.

With the above configuration, it is possible to provide a reflection-type liquid crystal display device which enables display by the birefringence effect, in which a twist structure is added to the conventional hybrid alignment mode. Therefore, the liquid crystal display device having the above configuration can be driven at a low voltage and has excellent responsiveness as compared with the conventional STN mode liquid crystal display device. Furthermore, since the alignment state of the liquid crystal has a twisted structure, it has a threshold value. Therefore, it can be driven by simple matrix driving, and the display capacity can be further increased.

Further, when a voltage is applied, the liquid crystal is oriented in a direction substantially normal to the first substrate, so that the birefringence becomes extremely small, and coloring due to the birefringence can be suppressed. Therefore, a liquid crystal display element having good whiteness can be provided. In addition, since the liquid crystal does not incline in the oblique direction unlike the conventional STN mode liquid crystal display device, the viewing angle is wide.

According to a thirteenth aspect of the present invention, in the liquid crystal display device according to the eleventh or twelfth aspect, the twist angle of the liquid crystal is in a range of 180 degrees or more and 270 degrees or less. Features.

As described above, the twist angle of the liquid crystal is set to 180.
By setting the temperature within the range of not less than degrees and not more than 270 degrees, steep threshold characteristics can be provided. This allows
Even when simple matrix driving is performed, the number of scanning lines, that is, the display capacity is not limited, and display with a large capacity can be performed.

According to a fourteenth aspect of the present invention, in the liquid crystal display device of the thirteenth aspect, the thickness of the liquid crystal layer is d,
D / p when the twist pitch of the liquid crystal is p is in the range of 0.3 or more and 0.9 or less.

According to the above configuration, it is possible to prevent a low-order twist in which the twist angle of the liquid crystal becomes small and also to prevent the generation of a stripe-shaped domain. It should be noted that the term "twist pitch of liquid crystal" used in the present specification means a pitch in a twist structure in which liquid crystal is not restricted by an alignment regulating force by an alignment film.

According to a fifteenth aspect of the present invention, in the liquid crystal display device according to any one of the eleventh to fourteenth aspects, the liquid crystal near the inner surface of the second substrate is the second substrate.
The liquid crystal is characterized by being oriented parallel to the substrate or oriented such that the pretilt angle of the liquid crystal is more than 0 degree and not more than 10 degrees.

With the above configuration, the change in the tilt angle of the liquid crystal between when a voltage is applied and when no voltage is applied can be made steep. That is, according to the above configuration, the steepness in the threshold characteristics can be improved.

According to a sixteenth aspect of the present invention, in the liquid crystal display device according to any one of the eleventh to fifteenth aspects, the pretilt angle of the liquid crystal in the vicinity of the inner surface of the first substrate is reduced. It is characterized by being within a range of 40 degrees or more and 90 degrees or less.

According to the above configuration, the liquid crystal in the vicinity of the first substrate is oriented at a high pretilt angle, so that when a voltage is applied, the orientation of the liquid crystal easily transitions to a new orientation at a low voltage. Let it. Therefore, the driving voltage can be reduced and the response can be excellent. Also, since the liquid crystal is oriented at a high pretilt angle as described above,
The viewing angle dependency can be reduced and a wide viewing angle can be obtained.

According to a seventeenth aspect of the present invention, there is provided the liquid crystal display element according to any one of the eleventh to sixteenth aspects, wherein the liquid crystal has a torsional elastic constant K ₂ and a bending elastic constant K 2. ₃ and the ratio K ₃ / K ₂ is 1.7 or more, and to be within the range of 2.5 or less.

As described above, the torsional elastic constant K ₂ ,
By setting the ratio K ₃ / K ₂ to the bending elastic constant K ₃ to 1.7 or more, the sharpness in the threshold characteristics can be increased. Therefore, the display capacity can be increased.

[0050] In order to solve the above-mentioned problems, the invention according to claim 18 is directed to any one of claims 11 to 17.
4. The liquid crystal display element according to any one of claims 1 to 3, wherein the electrodes provided on the inner side surfaces of the first substrate and the second substrate are respectively formed from a first electrode group or a second electrode group provided in a band at a predetermined interval. Wherein the first electrode group and the second electrode group intersect so as to form a matrix, and any one of the liquid crystal display element having such an electrode and the first electrode group and the second electrode group A first drive circuit for applying a scanning signal to one of the electrode groups; and a second drive circuit for applying a data signal to the other electrode group.

According to the above arrangement, the first and second driving circuits are mounted on the liquid crystal display element according to any one of the eleventh to seventeenth aspects, whereby the response and the viewing angle characteristics are improved. An excellent liquid crystal display device can be driven by a simple matrix driving method.

[0052]

(Embodiment 1) Embodiment 1 of the present invention will be described below with reference to FIGS. However, parts unnecessary for description are omitted, and some parts are shown enlarged or reduced for ease of description. The above applies to the following drawings.

FIG. 1 is a schematic sectional view showing a schematic configuration of a liquid crystal display device according to Embodiment 1 of the present invention. FIG.
FIG. 2 is a perspective view schematically showing an alignment state of liquid crystal in the liquid crystal display element. The liquid crystal display element includes a first substrate 1,
This is a configuration in which a liquid crystal layer 20 is provided between the second substrate 2. On the inner surface of the first substrate 1, a first electrode 3 is provided. Further, a liquid crystal is provided on the inner surface of the first electrode 3.
High pretilt alignment film 5 oriented in the normal direction of substrate 1
Are formed. On the other hand, a second electrode 4 is provided on the inner surface of the second substrate. Further, on the inner surface of the second electrode 4, a parallel alignment film 6 for aligning the liquid crystal in a direction parallel to the second substrate 2 is formed.

The liquid crystal layer 20 includes liquid crystals 7 as nematic liquid crystals (Np) having positive dielectric anisotropy, black dichroic dyes 8, and a chiral agent (not shown). ing. The liquid crystal 7a and the dichroic dye 8a near the high pretilt alignment film 5
Are oriented so as to be substantially perpendicular to the first substrate 1 under the orientation regulating force. Specifically, as shown in FIG.
The rubbing process is performed so that the rubbing direction of the high pretilt alignment film 5 coincides with the direction of the arrow X shown in the figure, and the liquid crystal 7a moves in the X direction, for example, the pretilt angle α _h
= 89 ° and tilted orientation. On the other hand, the liquid crystal 7b and the dichroic dye 8b in the vicinity of the parallel alignment film 6 are aligned in a direction substantially parallel to the second substrate 2 by receiving the alignment regulating force of the parallel alignment film 6. Specifically, the rubbing process is performed so that the rubbing direction of the parallel alignment film 6 coincides with the direction of the arrow Y shown in the figure, and the liquid crystal 7b moves in the Y direction, for example, at a pretilt angle α _l = 1. It is oriented at an angle in degrees. Further, the liquid crystal 7 and the dichroic dye 8 change the alignment state from a high tilt angle to a low tilt angle from the first substrate 1 to the second substrate 2 while changing a twist angle (ψ) 1.
The structure is twisted at 80 degrees. This is because the high pretilt alignment film 5 and the parallel alignment film 6 are arranged so that the rubbing directions thereof are opposite to each other, and the chiral agent is added to the liquid crystal layer 20. . The chiral agent is not particularly limited, and various conventionally known chiral agents can be used. Further, a chiral smectic liquid crystal may be added to form a twisted structure. The thickness d of the liquid crystal layer 20 is 5 μm.

Next, a method for manufacturing the liquid crystal display element according to the present embodiment will be described. First, a polyimide resin for vertical alignment is applied to the surface of the first electrode 3 formed on the first substrate 1 by a conventionally known method and then fired to form a high pretilt alignment film 5. On the other hand, a polyimide resin for parallel alignment is applied to the surface of the second electrode 4 formed on the second substrate 2 in the same manner as described above, followed by baking to form a parallel alignment film 6. Here, as a method for forming the high pretilt alignment film 5 and the parallel alignment film 6, in addition to the above method, lecithin or a silane-based surfactant is applied by a printing method, a dipping method, a spray method, or the like, Examples of the method include a method of vaporizing a surfactant. Further, a rubbing treatment is performed on the high pretilt alignment film 5 and the parallel alignment film 6 using a rubbing cloth in order to regulate the alignment direction of the liquid crystal or the like. In addition to the processing method using the rubbing cloth, a technique of determining the alignment direction by irradiating ultraviolet light having a polarization direction in a predetermined direction can be applied. Next, an empty cell is formed by pasting together via a spacer (not shown) so that the orientation direction on the second substrate 2 is twisted by 180 degrees with respect to the orientation direction on the first substrate 1 opposed thereto.

Subsequently, 95 wt% of nematic liquid crystal (Np), 1 wt% of chiral agent and black 2
A mixed solution obtained by mixing 4 wt% of a coloring pigment (p-type) is injected. As a result, the liquid crystal 7a and the dichroic dye 8a near the first substrate 1 are aligned in a direction substantially perpendicular to the first substrate 1 by the action of the alignment controlling force in the high pretilt alignment film 5. The liquid crystal 7b and the dichroic dye 8b near the second substrate 2 are actuated by the action of the alignment regulating force in the parallel alignment film 6.
Are oriented in a direction parallel to the second substrate 2. Further, the liquid crystal 7 in the liquid crystal layer 20 has a structure twisted by 180 degrees in the liquid crystal cell due to the action of the chiral agent. Thereby, the liquid crystal display device according to the present embodiment can be manufactured.

When no voltage is applied to the first electrode 3 and the second electrode 4, the liquid crystal display device having the above configuration is in a dark state (normally black). This is because the dichroic dyes 8 are arranged while being twisted, so that light vibrated in various directions can be absorbed or reflected. In the conventional hybrid alignment mode, only linearly polarized light oscillating in a direction parallel to the alignment direction of the liquid crystal could be used. However, the liquid crystal display device according to the present embodiment can display without using a polarizing plate, and can emit light. High utilization efficiency. On the other hand, when a voltage is applied to the first electrode 3 and the second electrode 4, the liquid crystal 7c near the center of the liquid crystal layer 20
Dissolves the twisted structure in the initial alignment state and rearranges it so as to be parallel to the direction of the electric field (the normal direction of the first substrate 1). Along with this, the dichroic dye 8c also changes interlockingly,
The arrangement state of the molecules is changed so as to be parallel to the normal direction. As a result, the light incident on the liquid crystal layer 20 is transmitted without being absorbed by the dichroic dyes 8a and 8c, and becomes a bright state.

Here, the present inventors conducted experiments and simulations on various parameters such as a twist angle and a pretilt angle in order to optimally design a hybrid alignment GH mode liquid crystal display device having a twist structure. . Hereinafter, these experiments and simulations and the results thereof will be described in detail.

(Distribution state of the tilt angle of the liquid crystal in the cell thickness direction) First, the distribution state of the tilt angle of the liquid crystal when no voltage is applied (in the cell thickness direction) is examined by simulation by changing the twist pitch p. did. FIG. 3 shows the result calculated by the simulation. In the figure, the vertical axis indicates the tilt angle θ of the liquid crystal 7..., And the horizontal axis indicates the distance (μm) from the second substrate 2. However, the thickness d of the liquid crystal layer 20 was 5 μm.

The curve 12 in the figure shows that the twist pitch p is 0 μm.
m, that is, the distribution of the tilt angle in the conventional non-twisted hybrid alignment mode. Curves 13 and 14 in the figure show the distribution of the tilt angle in the hybrid orientation mode twisted by 180 degrees according to the present embodiment, where curve 13 is p = 20 μm and curve 14 is p = 1.
The case of 0 μm is shown. The twist pitch p was prepared by changing the amount of the chiral agent added. As is clear from the figure, as compared with the case where the liquid crystal layer is not twisted (curve 12), the liquid crystal display element having the twisted structure has a smaller distribution of liquid crystal with a smaller tilt angle even with the same liquid crystal layer thickness. . In addition, the tendency that the tilt angle became smaller as the twist pitch p became shorter was remarkable. It was expected that the polarization dependence would be suppressed by twisting the alignment state of the liquid crystals 7 in the cell thickness direction. However, the effect of reducing the tilt angle of the liquid crystals 7 would reduce the dichroic dyes 8. It was found that the tilt angle was also reduced, thereby increasing the light absorptivity and causing the black to sink more.

In the liquid crystal panel actually assembled,
When no voltage is applied (that is, in a dark state), the transmittance at 20 μm drops to 80% of the transmittance without twisting,
In the case of μm, it decreased to 65%. This is due to the following. That is, in the case of the conventional hybrid alignment mode, since the light absorption axis of the dichroic dye is one axis, the light vibrating in all directions such as natural light vibrates in a direction other than the light absorption axis. Light cannot be absorbed. On the other hand, in the liquid crystal display element according to the present embodiment, the liquid crystal 7 and the dichroic dye 8 are twisted and made isotropic, so that light vibrating in all directions can be absorbed. Because. Moreover, the transmittance when a voltage of 3 V or more was applied was almost the same as in the conventional hybrid alignment mode. Therefore, for example, in the case of an applied voltage of 4 V, the twist pitch is 20 μm compared to the above-described conventional hybrid alignment mode.
And the contrast was improved by 50% at 10 μm. Therefore, it was found that the effect of twisting the alignment state of the liquid crystal was great for improving the contrast.

The simulation used in the present embodiment is based on software “Shintech Co., Ltd.” which calculates the orientation of liquid crystal molecules according to the elastic continuum theory of liquid crystal and calculates the optical characteristics by the method of Berremann. LCD MASTER ". The theory and method of calculation and its accuracy are known to those skilled in the art,
It has also been confirmed on various liquid crystal panels that the result of calculation by this software matches the characteristics of the actual panel (for example, the Liquid Crystal Device Handbook, pages 25-28, edited by the 142nd Committee of the Japan Society for the Promotion of Science). Pp. 61-64).

When a voltage is applied to the first electrode 3 and the second electrode 4, the liquid crystals 7 are aligned so as to be perpendicular to the first substrate 1 by an electric field effect. Dichroic dyes 8 ... also liquid crystal 7
(See FIG. 4).
The liquid crystal 7a near the first substrate 1 is oriented in a substantially vertical direction, and there is also a liquid crystal that is oriented at a high tilt angle by the action of the liquid crystal 7a. But it's easy to happen. For example, the threshold voltage of a conventional horizontal twisted nematic cell (STN mode) having a twist angle of 180 degrees manufactured by rubbing the inner surfaces of a pair of substrates so that the rubbing directions are parallel is usually 3V. It is about. On the other hand, the threshold voltage of the liquid crystal display element according to the present embodiment is 0.5 V, and when the active matrix driving by the TFT is performed, the driving at a low voltage becomes possible. Further, the transmittance of the liquid crystal display element according to the present embodiment is improved by 20% when a voltage of, for example, 4 V is applied, as compared with the conventional STN mode. This is because the liquid crystal 7a and the dichroic dye 8a near the first substrate 1
However, since the light is oriented so as to be substantially perpendicular to the first substrate 1, light absorption is reduced. Therefore,
The contrast was 1.5 times higher than that of the STN mode, which was excellent.

Therefore, in the hybrid alignment mode, by twisting the alignment state of the liquid crystal, a display with high contrast can be performed without the need for a polarizing plate. Further, by providing a color filter layer on the liquid crystal display device, a liquid crystal display device capable of full color display can be obtained.

(Relationship between Twist Angle of Liquid Crystal and Contrast Ratio) Next, the relationship between the twist angle of liquid crystal and the contrast ratio was examined. The twist angle ψ is equal to the thickness d (μ
By changing the twist pitch p (μm) while keeping m) constant, 0 °, 90 °, 180 °, 240 °, 270 °
And 300 degrees.

Before examining the relationship between the twist angle ψ and the contrast ratio, the change in transmittance when no voltage was applied when the twist angle ψ was changed was examined. The results are also shown in Table 1.

[Table 1] As is clear from Table 1 above, it was found that as the twist angle の of the liquid crystal was increased, the transmittance when no voltage was applied decreased. A dichroic dye absorbs only linearly polarized light oscillating in a direction parallel to its light absorption axis. Since this dichroic dye is arranged following the liquid crystal, the molecular arrangement state of the dichroic dye becomes isotropic as the twist angle increases, so that light vibrating in various directions can be absorbed. Become. Therefore, the transmittance when no voltage is applied is reduced.

On the other hand, when an applied voltage of 5 V was applied, the transmittance was almost the same at any twist angle. Here, the contrast ratio of each twist angle at an applied voltage of 5 V was determined. FIG. 5 shows the relationship between the contrast ratio and the twist angle ψ. As is apparent from FIG.
It was found that the value of the contrast ratio increased greatly up to 0 degrees, and gradually increased at a twist angle larger than that.

When the torsion angle is increased, the threshold voltage increases. For example, when the twist angle is 300 degrees, the threshold voltage is 6 V, so that the normal driving voltage range of 0 V
In order to drive at ~ 3v to 5v, the twist angle is preferably smaller than 300 degrees. In particular, when the torsion angle was 300 degrees, a hysteresis phenomenon in which the luminance was different when the applied voltage was increased and when the applied voltage was decreased occurred, whereas when the torsion angle was 270 degrees, the hysteresis phenomenon did not occur. Therefore, as the twist angle ψ,
It is desirable that the angle be 270 degrees or less where no hysteresis occurs. or,
The smaller the twist angle, the lower the voltage can be driven, but as is clear from FIG. 5, it is preferable that the twist angle is 180 degrees or more in order to secure a sufficient contrast.

(When the pretilt angle α _h is changed,
Distribution state of tilt angle of liquid crystal in cell thickness direction)
With respect to the distribution state of the tilt angle of the liquid crystal in the cell thickness direction in the absence of an electric field, the pretilt angle α _h of the liquid crystal 7a near the first substrate 1 was changed to 90 degrees, 70 degrees, 50 degrees, and 30 degrees. It was studied by simulation. The simulation was performed using the above-mentioned software “LCD MASTER” manufactured by Shintech Co., Ltd. or,
The twist angle is 180 degrees (d / p = 0.4), and the liquid crystal layer 20
The thickness d was calculated as 5 μm.

FIG. 6 shows the relationship between the tilt angle θ and the distance (μm) from the second substrate 2. As is clear from the figure,
Even when the distance from the second substrate 2 is the same, the pretilt angle α
It can be seen that the smaller the _h , the smaller the tilt angle θ.
Therefore, due to the effect of reducing the tilt angle of the liquid crystal,
It can be seen that the tilt angle of the dichroic dyes 8 is also reduced, thereby increasing the amount of light absorption and causing the black to sink.

On the other hand, the present inventors have also confirmed that the transmittance of the actually assembled liquid crystal panel when no voltage is applied (ie, in a dark state) is reduced. For example, the transmittance when the pretilt angle α _h is 70 degrees is reduced to 70% of the transmittance when the pretilt angle α _h is 90 degrees. On the other hand, when a voltage of 3 V was applied, the transmittances of the two were almost the same.
As a result, the contrast ratio was improved by about 40%. When the pretilt angle α _h was further tilted to 30 degrees, the transmittance when no voltage was applied was further reduced, and the contrast was improved. Also, the pretilt angle of the liquid crystal 7a near the first substrate 1 is
As the angle approaches 90 degrees, more liquid crystals having a high tilt angle are present, so that the alignment state can be changed even with a low applied voltage. As a result, responsiveness can be improved. From the above it, in order to make it is preferable to set so the pretilt angle alpha _h be within the range of 30 to 90 degrees, the driving voltage is in the range of 0v~3v or 0v~5v is Pre-tilt angle α _h is 50 degrees to 70
It is more preferable to set it within the range of degrees. It should be noted that the preparation of the pre-tilt angle α _h was carried out in the following manner. That is, as the material of the high pretilt alignment film 5, a material obtained by mixing a polyimide resin for vertical alignment and a polyimide resin for parallel alignment was used. By changing the mixing ratio of the two suitably, were prepared in the pretilt angle alpha _h.

The liquid crystals 7 in the liquid crystal layer 20 are twisted while changing the orientation from a high tilt angle to a low tilt angle from the first substrate 1 to the second substrate 2. Therefore,
Pretilt angle alpha _h of in the liquid crystal 7a in the first inner surface near the substrate 1 is, for example, in the case close to 90 degrees, since the liquid crystal of high tilt angles there are many, also changing its alignment state at a low applied voltage Can be. As a result, responsiveness can be improved. On the other hand, when the pretilt angle is close to 30 degrees, the liquid crystal having a low tilt angle increases, for example, as compared with the case where the pretilt angle is 90 degrees. As a result, the dichroic dyes 8 are arranged at a low tilt angle together with the liquid crystal 7, so that the amount of light absorbed by the dichroic dyes 8 when no voltage is applied increases. Therefore, the transmittance when no voltage is applied is reduced, and the contrast can be improved. Further, when the pretilt angle is an intermediate value in the above numerical range, a display device having good responsiveness and moderate contrast can be obtained.

(Relationship Between Elastic Constant Ratio and Contrast) Subsequently, a change in contrast when the elastic constant was changed was examined by simulation and experiment.
The simulation was performed using the above-mentioned software “LCD MASTER” manufactured by Shintech Co., Ltd.

Based on the elastic continuum theory, the orientation when no voltage was applied when the elastic constant of the liquid crystal was changed as shown in Table 2 below was determined, and the black reflectance when a black dichroic dye was added was obtained.
(That is, the reflectance in the black state) was calculated.

[Table 2] Here, the above elastic constants represent a splay elastic constant K ₁ , a twist elastic constant K _2, and a bend elastic constant K ₃ , and these constants are important physical properties related to the orientation of the liquid crystal.
No. 2 in Table 2 The liquid crystal of No. 5 shows the above-described nematic liquid crystal (Np) having a positive dielectric anisotropy, and the other liquid crystals are representative of elastic constants arbitrarily selected on the assumption that the liquid crystal is applicable to the present invention. The typical thing is shown. Furthermore, the pretilt angle α _{h is set} to 80 degrees, and the pretilt angle α _l
Is 1 degree, the twist angle ψ is 270 degrees, and the thickness d of the liquid crystal layer 20 is 5 degrees.
It was calculated as μm. Other physical property values such as the dielectric constant ε // in the alignment direction, the dielectric constant ε⊥ in the vertical component, the refractive index n // in the alignment direction, and the refractive index n⊥ in the vertical component are described in No. 1 and No. 2. 5 was the same as the liquid crystal. FIG. 7 shows a plot based on the results in Table 1 above. The vertical axis in the figure is the black reflectance (%),
The abscissa indicates the elastic constant ratio (-) of the liquid crystal, ○ indicates the elastic constant ratio K ₃ / K ₁ , □ indicates K ₃ / K ₂ , and × indicates K ₂ / K ₁ . As is clear from this figure, the value of K ₃ / K ₁ varies with the steepness and no correlation is seen, whereas the value of K ₃ / K ₂ (□) is distributed within the elliptical region 30. And is approximately in direct proportion to the black reflectance. on the other hand,
K ₂ / K ₁ (×) is distributed in the elliptical region 31 and has a roughly inverse proportional relationship. Here, regardless of the value of the elastic constant ratio, the transmittance when a voltage is applied is almost the same, and it can be said that the lower the black reflectance, the higher the contrast. Therefore, the value of K ₃ / K ₂ is small and the value of K ₂ / K ₁
The higher the value of the liquid crystal material, the better the contrast.
Specifically, a liquid crystal material having physical properties such that K ₃ / K ₂ is in the range of 1 or more and 2.5 or less, and further, K ₂ / K ₁ is in the range of 1 or more and 3 or less. Is preferable because the black reflectance is reduced and the contrast is improved. When a liquid crystal material having an elastic constant ratio outside the above numerical range is used, the liquid crystal is aligned at a higher tilt angle as compared with a liquid crystal material having an elastic constant ratio within the above numerical range. Here, since the dichroic dye is arranged following the liquid crystal, the amount of light absorption by the dichroic dye when no voltage is applied is reduced, and it can be said that black floats and the contrast is reduced. The above is
The same tendency was observed when the twist angle ψ and the pretilt angle were changed. Further, even when an experiment was conducted by actually manufacturing a liquid crystal panel, the same tendency as the calculation result by the simulation was confirmed. The reason why the lower limit of K ₃ / K ₂ is set to 1 is a value assuming a liquid crystal that can be applied in the present invention. Also, the upper limit of K ₂ / K ₁ is set to 3 for the same reason.

(Embodiment 2) Embodiment 2 of the present invention is described below with reference to FIG. Note that components having the same functions as those of the liquid crystal display element according to the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

In the first embodiment, a transmissive liquid crystal display element has been described as an example, but the technical idea of the present invention can be applied to a reflective liquid crystal display element. That is, as shown in FIG. 8, the configuration of the reflective liquid crystal display element according to the second embodiment is different from the configuration of the liquid crystal display element according to the first embodiment in that light is emitted outside the second substrate 2. The difference is that a reflective reflector 19 is provided. still,
Twist angle ψ 180 degrees, the pretilt angle alpha _h 89 °, the pretilt angle alpha _l is set to 1 degree.

In the reflective liquid crystal display device according to the present embodiment, when no voltage is applied between the first electrode 3 and the second electrode 4, the light incident from the first substrate 1 side is 180 degrees Since it is absorbed by the twisted dichroic dye 8, it becomes a dark state (normally black). In this case, the reflective liquid crystal display element according to the present embodiment is slightly worse than black in the 180-degree horizontal twisted nematic alignment cell (STN mode), but has a conventional hybrid alignment mode having no twisted structure. Compared with the transmittance, it can be reduced by 50%.

On the other hand, when a voltage is applied between the first electrode 3 and the second electrode 4, an electric field is generated in the liquid crystal layer 20 in a direction substantially normal to the second substrate 2. As a result, the liquid crystal 7 having a twisted structure and hybrid alignment is quickly transferred from the initial alignment state to a new alignment state. That is, the major axis direction of the liquid crystal 7c near the center of the liquid crystal layer 20 tends to be parallel to the electric field direction. The dichroic dye 8c also follows the liquid crystal 7c and attempts to align vertically with the first substrate 1. Therefore, the light incident on the liquid crystal layer 20 is transmitted without being absorbed by the dichroic dyes 8 and reaches the reflector 19. Further, the reflection plate 1
The light that has reached 9 is reflected by the reflection plate 19, passes through the liquid crystal layer 20 again, and exits the system. Here, the conventional S
In the TN mode, the liquid crystal in the vicinity of the substrate maintains the initial alignment state even when a voltage is applied. That is, the liquid crystal in the vicinity of the substrate is slightly parallel to the substrate surface, and therefore slightly absorbs light. on the other hand,
Also in the present embodiment, the liquid crystals 7a and 7b in the vicinity of the high pretilt alignment film 5 or the parallel alignment film 6 maintain the initial alignment state, but the liquid crystal 7a is originally the first substrate 1
And the dichroic dye 8a is also oriented in the same direction. Thereby, the dichroic dye 8a
Light can be suppressed and transmitted
The light reflectance can be greatly improved as compared with the conventional STN mode. For example, when the applied voltage is 3 V, ST
The reflectivity of the 180-degree twisted hybrid alignment cell of the present invention was 40% higher than that of the N mode. Therefore,
The contrast could be improved about 1.5 times that of the horizontal twisted nematic alignment cell. In addition, since the reflective liquid crystal display element according to the present embodiment has a twisted structure in the hybrid alignment mode, it can be driven at a low driving voltage by nature. Therefore, the reflective liquid crystal display element according to the present embodiment can be driven at low voltage and can display with high contrast.

The position of the reflection plate 19 is the first position shown in FIG.
The display screen may be disposed outside the substrate 1 and the second substrate 2 side may be used as the display screen. Further, the present invention is also applicable to a case where a metal material having light reflectivity such as aluminum (Al) is used for one of the first electrode 3 and the second electrode 4.

(Embodiment 3) Embodiment 3 of the present invention will be described with reference to FIG. The components having the same functions as those of the liquid crystal display device according to the first or second embodiment are denoted by the same reference numerals, and the detailed description is omitted.

As shown in FIG. 9, the liquid crystal display device according to the third embodiment has the first liquid crystal layer 21 to the third liquid crystal layer
It is a structure laminated on layers. More specifically, the first liquid crystal layer 21 is provided between the first substrate 1 and a first intermediate substrate 25 facing the first substrate 1. Second liquid crystal layer 2
2 is provided between the first intermediate substrate 25 and a second intermediate substrate 27 facing the first intermediate substrate 25. Further, the third liquid crystal layer 23 is provided between the second intermediate substrate 27 and the second substrate 2.

A third electrode 24 is provided on a surface of the first intermediate substrate 25 facing the first substrate 1, and a parallel alignment film 6 is provided on the third electrode 24. ing. Further, the second intermediate substrate 27 in the first intermediate substrate 25
The high pre-tilt alignment film 5 is provided on the surface facing. On the other hand, a fourth electrode 26 is provided on a surface of the second intermediate substrate 27 facing the first intermediate substrate 25, and the parallel alignment film 6 is provided on the fourth electrode 26. Further, a high pretilt alignment film 5 is provided on a surface of the second intermediate substrate 27 facing the second substrate 2.

The first liquid crystal layer 21 to the third liquid crystal layer 23 contain a chiral agent and liquid crystals 7. Further, the first to third liquid crystal layers 21 to 23 include positive dichroic dyes 9a to 11a having cyan, magenta or yellow colors, respectively. The dissolution concentration of each dye was adjusted from the absorbance to the incident light and the color level was adjusted.

Here, in a conventional liquid crystal display device using a color filter layer, since the amount of light transmitted through the color filter layer is small, the display screen becomes dark, and the color purity is poor particularly in the case of the reflection type. Was a problem. However, in the liquid crystal display element according to the present embodiment, the first liquid crystal layer 21 to the third liquid crystal layer containing the dichroic dyes 9a to 11a of cyan, magenta or yellow, respectively, without using the color filter layer. Since three layers 23 are stacked, there is no loss in the amount of light transmitted by the color filter layer. Further, each liquid crystal layer has a structure in which the conventional hybrid alignment mode is twisted, and by adopting such an alignment mode, transmittance when a voltage is applied can be improved. This is because the liquid crystal 7a in each liquid crystal layer is oriented so as to be substantially perpendicular to the substrate in the vicinity, and the dichroic dyes 9a to 11a are also substantially perpendicular to the liquid crystal 7a. This is because light is absorbed by these dichroic dyes 9a to 11a. Therefore, it is possible to provide a full-color liquid crystal display element with high utilization efficiency of incident light, high contrast, and good color purity.

In this embodiment, the first liquid crystal layer 21 has the first substrate 1 side as the high tilt angle side and the first intermediate substrate 25 side as the low tilt angle side. However, the present invention is not limited to this, and can be applied to the opposite case. Further, the second liquid crystal layer 22 and the third liquid crystal layer 2
The same applies to the case of No. 3, and which one is the higher tilt angle side or the lower tilt angle side may be appropriately adopted according to the circumstances at the time of applying the present invention.

(Embodiment 4) Embodiment 4 of the present invention will be described below with reference to FIGS. Note that components having the same functions as those of the liquid crystal display element of each of the above embodiments are given the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment, a liquid crystal display device including a dichroic dye has been described as an example. However, the liquid crystal display device according to the fourth embodiment is, as shown in FIG. The difference is that polarizing plates 44 and 45 are provided outside the display element. The difference is that row electrodes 40... Or column electrodes 41... Formed of a striped electrode group having a predetermined width are provided instead of the first electrode 3 and the second electrode 4. With such a configuration, it can be driven by simple matrix drive that realizes low cost,
It is possible to provide a liquid crystal display device of high display quality, which enables display by the birefringence effect. Hereinafter, the liquid crystal display device according to the present embodiment will be described in detail.

FIG. 11 shows the row electrode 40 and the column electrode 41.
It is a top view which shows the outline of. FIG. 12 is a perspective view schematically showing an alignment state of the liquid crystal in the liquid crystal layer 42. A plurality of stripe-shaped row electrodes 40 having a predetermined width are provided on the inner surface of the first substrate 1 (see FIG. 11), and a high pretilt alignment film 5 is provided on the inner surface of the row electrodes 40. Have been. On the other hand, a plurality of stripe-shaped column electrodes 41 having a predetermined width are provided on the inner surface of the second substrate 2 (see FIG. 11), and the parallel alignment film 6 is provided on the inner surface of the column electrodes 41. Have been. Further, the row electrodes 40 and the column electrodes 4
The first substrate 1 and the second substrate 2 are opposed to each other so as to intersect in a matrix.

The liquid crystal layer 42 is configured to include a positive nematic liquid crystal 7 to which a chiral agent is added. The above-mentioned liquid crystal 7 is formed of the N liquid used in the first embodiment.
o. 5, and the birefringence Δn is 0.142.
The liquid crystal 7a in the vicinity of the high pretilt alignment film 5 in the liquid crystal layer 42 is regulated by the high pretilt alignment film 5,
It is oriented so the pretilt angle alpha _h in the direction of arrow X is for example 70 degrees. On the other hand, the liquid crystal 7b in the vicinity of the parallel alignment film 6 in the liquid crystal layer 42 is aligned so that the pretilt angle _αl becomes, for example, 1 degree in the direction of the arrow Z under the control of the parallel alignment film 6. . Moreover, since the chiral agent is added, the liquid crystal 7 and the dichroic dye 8 have a twisted structure between the high pretilt alignment film 5 and the parallel alignment film 6. The twist pitch is about 7.0 μm, and the twist angle ２ is 2
It is set to 70 degrees. The thickness d of the liquid crystal layer 42 is 5.
It is 5 μm.

The arrangement relationship between the high pretilt alignment film 5 and the parallel alignment film 6 was set as follows. FIG.
FIG. 4 is a plan view when the relationship between the rubbing directions of the high pretilt alignment film 5 and the parallel alignment film 6 and the arrangement of the polarization axes in the polarizing plates 44 and 45 is observed from the first substrate 1 side. In the figure, the rubbing direction of the high pretilt alignment film 5 (that is, the inclination direction of the liquid crystal 7a near the high pretilt alignment film 5) is indicated by an arrow 46 in the figure. The parallel alignment film 6
The rubbing direction (that is, the tilt direction of the liquid crystal 7b near the parallel alignment film 6) is indicated by an arrow 47. Thereby, the liquid crystal layer 4
2 had a structure in which the liquid crystals 7 were twisted so as to draw a spiral in the direction of arrow 48. As shown in FIG. 13, the rubbing direction 46 of the high pretilt alignment film 5 and the polarizing plate 44
Is about 45 degrees, and the angle γ between the polarization axis 44 ′ and the polarization axis 45 ′ of the polarizing plate 45 is a right angle.

The liquid crystal display device having the above configuration is in a bright state (normally white) when no voltage is applied to the first electrode 3 and the second electrode 4. When the linearly polarized light transmitted through the polarizing plate 45 enters the liquid crystal layer 42, the linearly polarized light changes to elliptically polarized light due to the birefringence of the liquid crystal. Further, of the elliptically polarized light, only the polarized light that coincides with the polarization axis of the polarizing plate 44 is transmitted to be in a bright state. On the other hand, when a voltage is applied to the first electrode 3 and the second electrode 4, the liquid crystal 7c near the center of the liquid crystal layer 42 breaks the twisted structure that is in the initial alignment state, and the direction of the electric field (first
(The normal direction of the substrate 1). Along with this, the dichroic dye 8c also changes in an interlocking manner, and also changes the molecular arrangement state so as to be parallel to the normal direction. Here, the linearly polarized light transmitted through the polarizing plate 45 is uniformly oriented so that the liquid crystal 7 and the dichroic dye 8 in the liquid crystal layer 42 are perpendicular to the first substrate 1. ,
Transmitted without being absorbed by the dichroic dyes 8. Further, when this linearly polarized light reaches the polarizing plate 44, it does not pass because it does not coincide with the polarization axis of the polarizing plate 44. Therefore, it is in a dark state.

Next, the voltage-luminance characteristics of the liquid crystal display device according to the fourth embodiment will be described with reference to FIG. In FIG. 14, the horizontal axis indicates the effective voltage (v), and the vertical axis indicates the transmittance (%). As is clear from the characteristic curve shown in the figure, the threshold voltage Vth is 1.8 V, which is the threshold voltage (about 3 V) in the conventional STN mode.
v) is very low, about 2/3 as compared with the case of v).
Further, since the steepness of the threshold characteristic is high, for example, 1/24
A contrast ratio of 10 or more could be secured even with 0 duty drive. As described above, the conventional hybrid alignment does not have a threshold, but the threshold can be provided by introducing a twisted structure into the hybrid alignment mode as in the present invention.

Further, since the liquid crystal 7a near the high pretilt alignment film 5 has already been aligned in the normal direction of the first substrate 1 in the initial alignment state, the response speed is very high, twice or more that of the STN mode. is there. When a voltage is applied between the row electrode 40 and the column electrode 41, the liquid crystals 7 are aligned in a state nearly perpendicular to the first substrate 1, but in the conventional STN mode, some liquid crystals are The dependence on the viewing angle is smaller than in the STN mode rising in an oblique direction. Therefore, a liquid crystal display device having excellent characteristics as compared with the conventional simple matrix drive STN mode was obtained. Although the present embodiment does not use a phase difference plate, the contrast ratio can be further improved by inserting a phase difference plate and optimizing the optical characteristics. The position where the retardation plate is provided is the first substrate 1
And the polarizing plate 45 or the second substrate 2 and the polarizing plate 44 are preferable.

The liquid crystal display device according to the present embodiment has
The row electrodes 40 are connected and the first drive circuit is connected to the column electrodes 41.
(See FIG. 11), the slowest response speed and the greatest field of view in the conventional simple matrix drive liquid crystal display device are realized by mounting the second drive circuit for applying the data signal to the display device. A liquid crystal display device in which the narrowness of the corner is dramatically improved can be provided. The first drive circuit applies a scanning signal to the row electrodes 40, and the second drive circuit applies a data signal to the column electrodes 41. The first drive circuit drives based on a normal voltage averaging method. And

Here, the present inventors conducted simulations and experiments on various parameters such as a twist angle and a pretilt angle in order to optimally design a hybrid alignment mode liquid crystal display device having a twist structure. less than,
These simulations and experiments and their results will be described in detail.

(Relationship between Twist Angle 液晶 of Liquid Crystal and d / p) The optimum value of d / p (the ratio between the thickness d of the liquid crystal layer 42 and the twist pitch p) at which the alignment state of the liquid crystal becomes stable was examined. First, the high pretilt alignment film 5 and the parallel alignment film 6 are so adjusted that the twist angles １８０ are 180 °, 240 ° and 270 °, respectively.
Was rubbed to produce an empty cell. Liquid crystal materials having different added amounts of the chiral agent were injected into these empty cells, and the initial alignment state and the alignment state when voltage was applied were examined. The result is shown in FIG. As is apparent from FIG. 7, when the twist angle is 180 degrees, if d / p is smaller than 0.3, a low-order twist in which the twist angle is reduced occurs. When a small amount of was applied (when a low voltage was applied), stripe-like domains were generated. The twist angle is 24
In the case of 0 degrees, a low-order twist was generated when d / p was smaller than 0.5, and a stripe domain was generated when d / p was larger than 0.85. Further, the twist angle is 270.
In the case of the degree, when d / p was smaller than 0.5, a low-order twist was generated, and when d / p was larger than 0.9, a stripe domain was generated.

From these results, when the twist angle is 180 degrees, d / p is preferably in the range of 0.3 to 0.8. In the case of a twist angle of 240 degrees, d / p is 0.5.
０．８0.85, and the torsion angle 27
In the case of 0 degrees, d / p is preferably in the range of 0.5 to 0.9. Therefore, although the liquid crystal display element according to the present embodiment is in the hybrid alignment mode having a twisted structure, if d / p is not an appropriate value, the conventional S
It was found that the same poor orientation as in the TN mode occurred.

(Twist Angle of Liquid Crystal) Next, the twist angle of the liquid crystal was examined by simulation. Specifically, the twist angle ψ was changed to 0, 90, 180, 240, and 270 degrees, and the relationship between the applied voltage and the electric capacity of the liquid crystal at each twist angle ψ was calculated. The electric capacity of the liquid crystal increases when the major axis of the liquid crystal becomes parallel to the direction of the electric field when a voltage is applied, and thus serves as an index indicating a change in the alignment state of the liquid crystal. Therefore, the threshold characteristic can be understood by examining the change in the electric capacity of the liquid crystal. The threshold value obtained by this simulation substantially corresponds to the voltage-luminance characteristic of the liquid crystal display element in which the arrangement of the polarizing plate and the like are optimized based on the optical settings. The simulation was performed using the software “LCD MAS” manufactured by Shintec Co., Ltd.
TER ". Also, the high pretilt alignment film 5
The pretilt angle α _h of the liquid crystal in the vicinity is 80 degrees, and the parallel alignment film 6
The pretilt angle α ₁ of the liquid crystal in the vicinity was 1 degree, the thickness d of the liquid crystal layer 42 was 5.5 μm, the ordinary dielectric constant of the liquid crystal was 3.7, and the extraordinary optical dielectric constant was 11.5.

FIG. 16 shows an applied voltage-capacitance diagram obtained by calculating the change in the electric capacity of the liquid crystal with respect to the applied voltage. It can be seen that there is no threshold in the twist angle of 0 degree shown in FIG. In the case of a twist angle of 90 degrees (d / p = 0.25),
Although there is a slight threshold voltage of about 0.2 V, the steepness is poor and the simple matrix drive with the smallest display capacity is used.
It can be seen that even / 3 duty driving is difficult. Therefore, it is not suitable for simple matrix driving. 180 twist angle
In the case of the degree (d / p = 0.5), a threshold value comparable to that of the conventional TN mode can be obtained, so that it can be used in a display having a small display capacity. On the other hand, the twist angle is 240 degrees (d / p =
In the case of 0.7) to 270 degrees (d / p = 0.75), the steepness is very large, and particularly at 270 degrees, steepness comparable to the STN mode capable of large-capacity display is obtained. ing. When the torsion angle reaches 300 degrees, a curve (not shown) that draws an S-shape is formed, and a hysteresis phenomenon appears.
The twist angle ψ is preferably in the range of 180 to 270 degrees. In particular, when the twist angle is in the range of 240 degrees to 270 degrees, a dot matrix type large-capacity display is also possible.
Further, as can be seen from FIG. 16, the driving voltage of the liquid crystal display element according to the present embodiment is in the range of 1 V or more and less than 2 V, which is about 2/3 as compared with the driving voltage in the conventional STN mode. It has been reduced. In a region where the orientation state is stable, the steepness increases as the value of d / p increases. For example, when the twist angle is 240 degrees or more, d / p is 0.1.
It is preferably 6 or more.

(Pretilt Angle of Liquid Crystal) First Embodiment
In, for GH mode with dichroic dye have been studied pretilt angle alpha _h of the first substrate 1 side of the liquid crystal 7a, the threshold characteristics pretilt angle alpha _h even in the present embodiment The effect was examined by simulation. Specifically, the pretilt angle α _h is 90
, 85, 80, 70, 50, and 30 degrees, and the relationship between the applied voltage and the electric capacity of the liquid crystal at each pretilt angle α _h was calculated. As described above, the threshold value obtained by this simulation substantially corresponds to the voltage-luminance characteristic of the liquid crystal display element in which the optical settings such as the arrangement of the polarizing plates are optimized. The simulation was performed using the above-mentioned software “LCD MASTER” manufactured by Shintech Co., Ltd. The twist angle ２ is 270 degrees, the pretilt angle α _l of the liquid crystal near the parallel alignment film 6 is 1 degree, the thickness of the liquid crystal layer 42 is 5.5 μm, the ordinary dielectric constant of the liquid crystal is 3.7, and the extraordinary optical dielectric constant is 11.5.

FIG. 17 shows an applied voltage-capacitance characteristic diagram in which a change in the electric capacity of the liquid crystal with respect to the applied voltage is calculated.
As shown in the figure, the steepness of threshold characteristic, it can be seen that a large influence of the pretilt angle alpha _h of high pretilt alignment film 5 side. Specifically, steepness as the pretilt angle alpha _h is smaller is larger. When the pretilt angles are 80 degrees, 70 degrees, and 50 degrees, there is no large difference in steepness. Further, when the pretilt angle is 30 degrees, the steepness is good, but the driving voltage is large. Moreover,
At this pretilt angle, since the liquid crystal layer 42 is greatly inclined with respect to the normal line of the first substrate 1, the liquid crystal layer 42 has a high proportion of liquid crystal having a small tilt angle. Therefore, when a voltage is applied, it takes time until the liquid crystal is aligned in the normal direction of the first substrate 1, and the response speed is reduced. For the same reason, the viewing angle dependency becomes larger and the viewing angle becomes narrower than when the pretilt angle is high. Therefore, the pretilt angle α _h is about 40 when the applied voltage is desired to be kept lower than 2.5 V.
It is more preferable that the temperature is not less than the degree. Therefore, the pretilt angle α _h
Is preferably in the range of 90 degrees or more and 40 degrees or less. In particular, when performing large-capacity display requiring a steep threshold characteristic, it is more preferable that the angle be in the range of 50 degrees or more and 85 degrees or less.

The pretilt angle α _l of the liquid crystal 7b near the parallel alignment film 6 is preferably in the range of 0 ° to 10 °. This makes it possible to sharply change the tilt angle of the liquid crystal between when a voltage is applied and when no voltage is applied, and it is possible to improve the steepness in threshold characteristics. When the pretilt angle alpha _l exceeds 10 degrees, since the steepness is lost undesirably.

(Relationship between Elastic Constant Ratio and Steepness)
Using the various liquid crystals shown in Table 1, the relationship with the steepness in the threshold characteristics was examined. FIG. 18 shows the result. The steepness shown on the vertical axis in the figure was obtained as follows. That is, the applied voltage shown in FIG. 17 - In the curve of the in pretilt angle alpha _h the capacitance characteristic 80 degrees, the steepest part of the slope (the in electric capacity in the voltage range 0.1v changes Ratio), and this was defined as steepness.
The pretilt angle α _h is 80 degrees, and the pretilt angle α _l is 1
Degree, the twist angle is 270 degrees, and the thickness d of the liquid crystal layer 42 is 5.5 μm.
m.

As shown in FIG. 18, K ₃ / K ₁ (in FIG. 18,
No correlation with steepness was observed in K / K ₁ (shown by ×) or K ₂ / K ₁ (shown by × in the figure). However, K ₂
/ K ₁ (indicated by □ in the figure), the elliptical area 63
And is proportional to the steepness. In particular,
When the value of K ₂ / K ₁ is smaller than 2, the steepness sharply decreases, so that it is preferable that K ₂ / K ₁ be in the range of 1.7 or more and 2.5 or less. The same tendency was observed even when the twist angle and the pretilt angle were changed. Further, even when an experiment was conducted by actually manufacturing a liquid crystal panel, the same tendency as the calculation result by the simulation was confirmed. Note that the upper limit of K ₂ / K ₁ is set at 2.5 assuming a liquid crystal applicable in the present invention.

As described above, according to the liquid crystal display device of the present embodiment, since the liquid crystal display device has a threshold characteristic with a large steepness, it can be driven at a low voltage by a simple matrix driving method. In addition, a liquid crystal display device having high contrast, excellent viewing angle and excellent responsiveness can be obtained.

In this embodiment mode, a mode in which a pair of polarizing plates is used has been described. In addition, a polarizing plate is provided outside one of the pair of substrates, and the other substrate is used. By providing a reflective plate on the outside, a reflective liquid crystal display element having a wide viewing angle, good contrast and good whiteness can be obtained. Here, the reason why the whiteness is good is as follows. That is, since the liquid crystal molecules are close to the vertical alignment when a voltage is applied, the linearly polarized light transmitted through the polarizing plate propagates as it is. That is, since birefringence becomes extremely small, coloring due to birefringence can be suppressed.

In each of the above embodiments, the case where a nematic liquid crystal Np having a positive dielectric anisotropy is used has been described, but the present invention is not limited to this. For example, a nematic liquid crystal Nn having a negative dielectric anisotropy
Alternatively, a mixture of nematic liquid crystals Np and Nn of both positive and negative dielectric anisotropy can be applied.

[0108]

The present invention is embodied in the form described above and has the following effects.

That is, according to the liquid crystal display device of the present invention, a GH mode liquid crystal display device in which a twist structure is added to the conventional hybrid alignment mode can be driven at a low driving voltage. This has the effect of enabling high-contrast display.

According to the liquid crystal display device of the present invention,
By using a liquid crystal display element having a polarizing plate and adding a twisted structure to the conventional hybrid alignment mode and capable of displaying by the birefringence effect, a threshold characteristic with a large steepness can be provided. It can be driven with a low driving voltage by a simple matrix driving method. Further, there is an effect that a liquid crystal display element having excellent viewing angle and responsiveness can be obtained.

Further, according to the liquid crystal display device of the present invention, the scanning signal is transmitted to the liquid crystal display element having a polarizing plate and having a twist structure added to the conventional hybrid alignment mode and capable of displaying by the birefringence effect. The provision of the first driving circuit for applying the voltage and the second driving circuit for applying the data signal has the effect that the liquid crystal display device having excellent responsiveness and viewing angle characteristics can be driven by the simple matrix driving method. Play.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view schematically showing a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically showing an alignment state of liquid crystal in the liquid crystal display device.

FIG. 3 is a characteristic diagram showing a relationship between a tilt angle θ of a liquid crystal and a distance from a second substrate in the liquid crystal display device.

FIG. 4 is a schematic sectional view showing a state when an electric field is applied to the liquid crystal display element.

FIG. 5 is a characteristic diagram showing a relationship between a twist angle 液晶 of a liquid crystal and a contrast ratio in the liquid crystal display element.

FIG. 6 is a characteristic diagram showing a relationship between a tilt angle θ of a liquid crystal and a distance from a second substrate in the liquid crystal display element.

FIG. 7 is a graph showing a relationship between a liquid crystal elastic constant ratio and black reflectance in the liquid crystal display device.

FIG. 8 is a schematic cross-sectional view schematically showing a liquid crystal display device according to a second embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view schematically showing a liquid crystal display element according to Embodiment 3 of the present invention.

FIG. 10 is a schematic cross-sectional view schematically showing a liquid crystal display element according to a fourth embodiment of the present invention.

FIG. 11 is a plan view schematically showing a row electrode and a column electrode in the liquid crystal display element.

FIG. 12 is a perspective view schematically showing an alignment state of liquid crystal in the liquid crystal display device.

FIG. 13 is a plan view showing a relationship between a rubbing direction and a polarization axis of a polarizing plate in the liquid crystal display device.

FIG. 14 is a characteristic diagram showing a relationship between transmittance and effective value voltage in the liquid crystal display element.

FIG. 15 is a graph showing a relationship between a twist angle 液晶 of liquid crystal and d / p in the liquid crystal display element.

FIG. 16 is a characteristic diagram showing the relationship between the capacitance and the applied voltage when the twist angle ψ of the liquid crystal in the liquid crystal display element is variously changed.

FIG. 17 is a characteristic diagram showing a relationship between an electric capacity and an applied voltage when the pretilt angle α _h of the liquid crystal in the liquid crystal display element is variously changed.

FIG. 18 is a graph showing a relationship between an elastic constant ratio of liquid crystal and steepness in the liquid crystal display device.

FIG. 19 is a schematic cross-sectional view schematically showing a conventional liquid crystal display element.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st substrate 2 2nd substrate 3 1st electrode 4 2nd electrode 5 High pretilt alignment film 6 Parallel alignment film 7a-c Liquid crystal 8a-c Dichroic dye 9 Cyan dichroic dye 10 Magenta two colors Dye 11 Yellow dichroic dye 19 Reflector 20 Liquid crystal layer 21 First liquid crystal layer 22 Second liquid crystal layer 23 Third liquid crystal layer 25 First intermediate substrate 26 Second intermediate substrate 40 Row electrode 41 Column electrode 44, 45 Polarizer α _h , α _l Pretilt angle θ Tilt angle ψ Twist angle

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiko Yamanaka 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Hiroshi Yamazoe 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) 2H088 GA02 GA13 GA17 HA18 HA21 JA06 JA13 KA08 KA12 LA05 LA08 MA02 MA09 2H089 HA09 HA23 HA29 HA30 HA32 QA16 RA06 RA10 SA06 SA07 SA08 TA17

Claims (18)

[Claims] A liquid crystal layer including liquid crystal is provided between a pair of substrates provided with electrodes and opposed to each other, and a liquid crystal near an inner surface of the first substrate is provided on the inner surface of the first substrate. An orientation process is performed on the first substrate so that the pretilt angle is inclined and oriented within a range of 30 degrees or more and 90 degrees or less. In a liquid crystal display device which has been subjected to an alignment treatment so as to align a liquid crystal near an inner surface in a direction substantially parallel to the second substrate, the liquid crystal layer contains a dichroic dye and a chiral agent. A liquid crystal display device, wherein the liquid crystal in the liquid crystal layer has a twisted structure. 2. The twist angle of the liquid crystal is 180 degrees or more,
2. The liquid crystal display device according to claim 1, wherein the angle is within 70 degrees. 3. The liquid crystal display device according to claim 1, wherein a pretilt angle of the liquid crystal near the inner surface of the first substrate is in a range of 50 degrees or more and 70 degrees or less. . 4. The liquid crystal in the vicinity of the inner surface of the second substrate is oriented parallel to the second substrate, or the pretilt angle of the liquid crystal is in a range of more than 0 ° and 10 ° or less. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is oriented so as to be: 5. A torsional elastic constant K _{2 in the} liquid crystal,
Bending elastic constant K ₃ as the ratio K ₃ / K ₂ is 1 or more, the liquid crystal display device according to any one of claims 1 to 4, characterized in that in the range of 2.5 or less. 6. The spread elastic constant K in the liquid crystal.
The liquid crystal display device according to claim 1, wherein a ratio K ₂ / K ₁ between ₁ and a torsional elastic constant K ₂ is in a range of 1 or more and 3 or less. . 7. The liquid crystal display device according to claim 1, wherein a reflection plate is provided behind the liquid crystal layer. 8. A liquid crystal display device having an electrode on an inner surface thereof and a liquid crystal layer provided between a first substrate and a second substrate disposed opposite to each other, wherein the liquid crystal layer is By interposing a first intermediate substrate and a second intermediate substrate spaced from each other between the first substrate and the second substrate, a three-layer structure of a first liquid crystal layer to a third liquid crystal layer is formed. The first liquid crystal layer is provided between the first substrate and a first intermediate substrate facing the first substrate and having an electrode on any one of the surfaces. The second liquid crystal layer is provided on the first liquid crystal layer. A third intermediate liquid crystal layer provided between the first intermediate substrate and a second intermediate substrate facing the first intermediate substrate and having an electrode on one of the surfaces; A first liquid crystal layer, a third liquid crystal layer, and a third liquid crystal layer. The liquid crystal in the vicinity of the inner surface of the substrate is subjected to an alignment treatment so as to be inclined with respect to the substrate within a range of a pretilt angle of 30 degrees or more and 90 degrees or less, and the first liquid crystal layer to the third liquid crystal layer And an alignment process is performed on the other inner surface of the substrate sandwiching each of the first liquid crystal layer and the third liquid crystal layer to align the liquid crystal near the other inner surface in a direction substantially parallel to the substrate. The liquid crystal layer contains dichroic dyes of colors selected from cyan, magenta and yellow differently from each other and contains a chiral agent. Further, the liquid crystal in the first to third liquid crystal layers is A liquid crystal display element having a twisted structure. 9. The liquid crystal has a twist angle of 180 degrees or more,
9. The liquid crystal display device according to claim 8, wherein the angle is within a range of 70 degrees or less. 10. A pre-tilt angle of a liquid crystal in the vicinity of an inner surface of a substrate sandwiching each of the first to third liquid crystal layers, which has been subjected to an alignment treatment so as to be aligned in a direction perpendicular to the substrate.
10. The liquid crystal display device according to claim 8, wherein the angle is in a range of 0 degrees or more and 70 degrees or less. 11. A liquid crystal layer including a liquid crystal is provided between a pair of substrates disposed opposite to each other, including an electrode on an inner surface thereof, and an inner surface of a first substrate among the substrates is provided near an inner surface thereof. The liquid crystal is oriented so as to be inclined with respect to the first substrate in a range of a pretilt angle of not less than 40 degrees and not more than 90 degrees. Is a liquid crystal display element that has been subjected to an alignment treatment so as to align liquid crystal near its inner surface in a direction substantially parallel to the substrate, comprising a polarizing plate outside the pair of substrates, A liquid crystal display device comprising a layer containing a chiral agent and a liquid crystal in the liquid crystal layer having a twisted structure. 12. A liquid crystal layer including a liquid crystal is provided between a pair of substrates disposed opposite to each other, including an electrode on an inner surface thereof, and an inner surface of a first substrate of the substrate is provided near an inner surface thereof. The liquid crystal is oriented so as to be inclined with respect to the first substrate in a range of a pretilt angle of not less than 40 degrees and not more than 90 degrees. Is a liquid crystal display element that has been subjected to an alignment treatment so as to align liquid crystal near its inner surface in a direction substantially parallel to the substrate, wherein a polarizing plate is provided in front of the liquid crystal layer, and A liquid crystal display element, further comprising: a reflecting plate provided behind the liquid crystal layer; and a liquid crystal layer containing a chiral agent, wherein the liquid crystal in the liquid crystal layer has a twisted structure. 13. The liquid crystal has a twist angle of 180 degrees or more,
2. The method according to claim 1, wherein the angle is within 270 degrees or less.
The liquid crystal display device according to claim 1. 14. The method according to claim 13, wherein d / p is 0.4 to 0.9 when the thickness of the liquid crystal layer is d and the twist pitch of the liquid crystal is p. The liquid crystal display element as described in the above. 15. The liquid crystal in the vicinity of the inner surface of the second substrate is oriented parallel to the second substrate, or the liquid crystal has a pretilt angle of more than 0 ° and not more than 10 °. 12. An alignment according to claim 11, wherein
The liquid crystal display device according to claim 14. 16. The liquid crystal display device according to claim 11, wherein a pretilt angle of the liquid crystal near the inner surface of the first substrate is in a range of 40 degrees or more and 90 degrees or less. 3. The liquid crystal display device according to item 1. 17. The torsional elastic constant K in the liquid crystal
₂ and the ratio K ₃ / K _{2 of} the bending elastic constant K ₃ to 1.7 or more,
12. The method according to claim 11, wherein the distance is within 2.5 or less.
A liquid crystal display device according to claim 16. 18. The liquid crystal display device according to claim 11, wherein the electrodes provided on the inner surfaces of the first substrate and the second substrate have a predetermined distance from each other. A first electrode group or a second electrode group provided in a strip shape, and the first electrode group and the second electrode group intersect so as to form a matrix. A first drive circuit for applying a scan signal to one of the first electrode group and the second electrode group, and a second drive circuit for applying a data signal to the other electrode group. A liquid crystal display device characterized in that: