JP2008102288A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display which can obtain ample luminosity and is low in power consumption. <P>SOLUTION: In the liquid crystal display, having a pair of substrates 101 and 102 facing each other and a liquid crystal layer 104 interposed between the pair of substrates 101 and 102 and having a plurality of layers comprising a refractive index anisotropic medium aligned in the same direction, the plurality of layers are disposed to be nearly parallel to the surfaces of the pair of substrates 101 and 102, refractive index difference between adjacent layers in the plurality of layers is controlled by electric field and either of the pair of substrates 101 and 102 has a light absorption plate AP that absorbs light, made incident in the liquid crystal layer 104. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a reflective liquid crystal display device.

  In recent years, liquid crystal display devices have been applied to various fields such as notebook personal computers, monitors, car navigation systems, scientific calculators, and small and medium-sized TVs. In particular, the reflection type liquid crystal display element is applied to a display for a portable device in order to take advantage of low power consumption, thinness and light weight because a backlight is not required.

  However, conventional reflective liquid crystal display elements have display performance that is inferior in terms of brightness compared to paper, printed matter, and the like. In addition, transmissive liquid crystal display elements are also applied to displays for portable devices. In addition, since the battery is used as a power source, if an attempt is made to obtain a sufficient driving time, the brightness of the backlight must be lowered, and sufficient brightness cannot be obtained.

  One of the factors that cause the brightness of these liquid crystal display elements to be insufficient is light absorption by a member necessary for controlling the brightness of the display, for example, a polarizing plate used in the TN mode or the ECB mode.

  As a means for solving this problem, there is a scattering type liquid crystal display element represented by a polymer dispersed liquid crystal (PDLC). It uses scattering and scattering reflection of incident light due to the difference in refractive index between the randomly arranged liquid crystal and the isotropic layer having no refractive index anisotropy or the difference in refractive index between the molecules of the randomly arranged liquid crystal. .

When this scattering type liquid crystal display device is used as a reflection type liquid crystal display device, it becomes a bright state by scattering reflection. Apply an electric field to the liquid crystal layer to make the refractive index of the isotropic layer and the liquid crystal layer equal to the direction in which the light is incident, or make the refractive index between molecules of the liquid crystal layer equal, and the rear side of the liquid crystal display device The incident light is absorbed by the light-shielding layer arranged in (1) to obtain a dark state (see Patent Document 1).
JP 11-38452 A

  However, the difference in refractive index between the randomly arranged liquid crystal and the isotropic layer without refractive index anisotropy in the scattering type liquid crystal display device is the average of the extraordinary refractive index and ordinary refractive index of liquid crystal molecules, and the ordinary refractive index. However, the liquid crystal material currently used practically can only obtain about 0.13 at most. For this reason, in order to obtain a sufficient reflectance, it is necessary to increase the thickness of the liquid crystal layer, and the driving voltage of the liquid crystal becomes extremely high. Then, power consumption becomes high.

  Further, when the conventional scattering type liquid crystal display device is used as a reflection type, sufficient brightness is not obtained, and as a result, the contrast ratio is insufficient.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a reflective liquid crystal display device that can obtain sufficient brightness and low power consumption.

  A liquid crystal display device according to an aspect of the present invention includes a pair of substrates facing each other and a liquid crystal layer that is sandwiched between the pair of substrates and includes a plurality of layers made of a refractive index anisotropic medium oriented in the same direction. And the plurality of layers are arranged substantially parallel to the substrate surfaces of the pair of substrates, and the difference in refractive index between adjacent layers is controlled by electric field control, One of the pair of substrates has a light absorbing plate that absorbs light incident on the liquid crystal layer.

  According to the present invention, it is possible to provide a reflective liquid crystal display device that can obtain sufficient brightness and consumes low power.

  A liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the liquid crystal display device according to this embodiment includes a pair of substrates facing each other, that is, an array substrate 101 and a counter substrate 102, and a liquid crystal layer 104 sandwiched between the array substrate 101 and the counter substrate 102. A reflective liquid crystal display panel 100 having

  The liquid crystal display panel 100 has a display area 110 composed of a plurality of display pixels PX arranged in a matrix and a peripheral area 120 surrounding the display area 110. As shown in FIG. 1, the display area 110 is formed in an area surrounded by the outer edge seal member 103, and a peripheral area 120 is arranged along the outer periphery thereof.

  In the display area 110, as shown in FIG. 2, a plurality of signal lines X (X1 to Xn) and a plurality of scanning lines Y (Y1 to Ym) are arranged to intersect each other. In the peripheral region 120 shown in FIG. 1, the array substrate 101 includes a scanning line driving circuit 121 that drives the scanning line Y and a signal line driving circuit 122 that drives the signal line X.

  In the display area 110, the array substrate 101 includes m × n pixel electrodes 131 arranged in a matrix and arranged in each display pixel PX. On the other hand, the counter substrate 102 includes a counter electrode 173 that faces all the pixel electrodes 131 with the liquid crystal layer 104 interposed therebetween.

  5 and 6 are diagrams schematically illustrating an example of the liquid crystal display device according to the present embodiment. As shown in FIG. 5, in the liquid crystal display device according to the present embodiment, the liquid crystal layer 104 has a plurality of layers substantially parallel to the substrate surfaces of the array substrate 101 and the counter substrate 102. In a state where no voltage is applied to the pixel electrode 131 and the counter electrode 173, the tilt direction of the liquid crystal molecules is antiparallel in each layer.

  For this reason, the liquid crystal layer 104 acts as a medium having a different refractive index between the liquid crystal layers for light components incident from a certain direction in the major axis direction of the liquid crystal molecules. Here, in the description of the present embodiment, the major axis orientation of the liquid crystal molecules refers to a component in a plane substantially parallel to the substrate surfaces of the array substrate 101 and the counter substrate 102 in the major axis direction of the liquid crystal molecules. Therefore, the light incident on the liquid crystal layer 104 is reflected at the boundary surfaces of the plurality of layers. If it does so, light will be reflected in multiple by the interface between several layers, and will be in a white display state.

  On the other hand, in a state where a voltage is applied to the pixel electrode 131 and the counter electrode 173, the liquid crystal molecules have a substantially homeotropic alignment due to the electric field generated in the liquid crystal layer 104. For this reason, the liquid crystal layer 104 acts as an optically isotropic medium. Therefore, the light incident on the liquid crystal layer 104 is not reflected by the boundary surfaces of the liquid crystal layers 104 but is absorbed by the light absorbing plate AP to be in a black display state.

  That is, light reflection occurs when the total reflection condition (sin θ <ne / no) is satisfied, and the display state can be switched by controlling the refractive index of a plurality of layers using the condition. . Here, it is assumed that the refractive index anisotropic medium of the liquid crystal layer 104, that is, the refractive index of the major axis direction of the liquid crystal molecules is ne, and the refractive index of the direction substantially orthogonal thereto is no.

  Therefore, as described above, when the array substrate 101 has the light absorption plate AP, the array substrate 101 can perform reflection display without having a reflective electrode. Further, in this display method, a polarizing plate used in a conventional liquid crystal display device is not necessary, so that very bright reflective display and transmissive display are possible.

  The array substrate 101 includes m × n thin film transistors (TFTs) arranged as switching elements 140 in the vicinity of the intersection of the scanning lines Y and the signal lines X corresponding to the m × n pixel electrodes 131. .

  The source electrode 145 (shown in FIG. 4) of the switching element 140 is connected to (or integrated with) the corresponding signal line X. The gate electrode 143 (shown in FIG. 4) of the switching element 140 is connected to (or integrated with) the corresponding scanning line Y. The drain electrode 144 (shown in FIG. 4) of the switching element 140 is connected to (or integrated with) the pixel electrode.

  The array substrate 101 includes auxiliary capacitance electrodes 151 at the respective pixel electrodes 131 so as to have the same potential. The array substrate 101 further includes an auxiliary capacitance line 152 connected to each auxiliary capacitance electrode 151, and a counter electrode driving circuit 123 connected to each auxiliary capacitance line 152 and the counter electrode 173. The counter electrode drive circuit 123 controls each auxiliary capacitance line 152 and the counter electrode 173 to a predetermined potential. The auxiliary capacitance is constituted by each auxiliary capacitance electrode 151 and the auxiliary capacitance line 152 connected thereto.

  FIG. 3 is a cross-sectional view of the liquid crystal display panel 100 in the vicinity of the boundary between the peripheral region 120 and the display region 110. 4 is a cross-sectional view of the array substrate 101 in the vicinity of the intersection between the scanning line Y and the signal line X shown in FIG. In the following, each component shown in FIGS. 3 and 4 will be described.

  As shown in FIGS. 3 and 4, an undercoat layer 112 is disposed on the insulating substrate 111 in the display region 110 of the array substrate 101. A switching element 140 is disposed on the undercoat layer 112.

  In the switching element 140, a semiconductor layer 141 formed of a polysilicon film is disposed on the undercoat layer 112. The semiconductor layer 141 includes a channel region 141C and a drain region 141D and a source region 141S formed by doping impurities on both sides thereof. On the undercoat layer 112, an auxiliary capacitance electrode 151 made of an impurity-doped polysilicon film is disposed.

  A gate insulating film 142 is formed on the undercoat layer 112, the semiconductor layer 141, and the auxiliary capacitance electrode 151. On the gate insulating film 142, a gate electrode 143, a scanning line Y integrated therewith, and an auxiliary capacitance line 152 are formed. A part of the auxiliary capacitance line 152 faces the auxiliary capacitance electrode 151. The auxiliary capacitance line 152 is formed of the same material as the scanning line Y and extends substantially parallel to the scanning line Y.

  An interlayer insulating film 113 is disposed on the gate insulating film 142, the gate electrode 143, the scanning line Y, and the auxiliary capacitance line 152. A drain electrode 144, a signal line X, a source electrode 145, and a contact electrode 153 are disposed on the interlayer insulating film 113.

  The signal line X is disposed so as to be substantially orthogonal to the scanning line Y and the auxiliary capacitance line 152. Further, the signal line X, the scanning line Y, and the auxiliary capacitance line 152 are formed of a low resistance material having a light shielding property.

  For example, the scanning line Y and the auxiliary capacitance line 152 are formed of molybdenum-tungsten, and the signal line X is often formed of aluminum. The drain electrode 144 and the source electrode 145 include the gate insulating film 142 and the interlayer insulating film. The drain region 141D and the source region 141S are connected to the drain region 141D and the source region 141S, respectively, through contact holes 114A and 114B penetrating the 113.

  The contact electrode 153 is connected to the auxiliary capacitance electrode 151 through a contact hole 154 that penetrates the gate insulating film 142 and the interlayer insulating film 113. The contact electrode 153 is formed of the same material as the signal line X and is connected to the signal line X. Therefore, the source electrode 145, the pixel electrode 131, and the auxiliary capacitance electrode 151 have the same potential.

  In the display region 110, a transparent resin layer 115 is further disposed on the interlayer insulating film 113, the drain electrode 144, the source electrode 145, the scanning line Y, the signal line X, and the contact electrode 153. In the peripheral region 120, a light shielding layer 116 is further disposed.

  On the transparent resin layer 115, a pixel electrode 131 is disposed by a light transmissive conductive member such as ITO (Indium Tin Oxide). The pixel electrode 131 is connected to the source electrode 145 of the switching element 140 through a through hole 117 that penetrates the transparent resin layer 115. On the transparent resin layer 115, for example, a columnar spacer 118 having a height of 2.0 μm is disposed.

  An alignment film 119 is disposed on the transparent resin layer 115 and the pixel electrode 131 so as to cover the columnar spacer 118. The alignment film 119 aligns the liquid crystal 106 included in the liquid crystal layer 104 in a direction substantially perpendicular to the substrate surface of the array substrate 101.

  On the other hand, the counter substrate 102 includes a transparent insulating substrate 171 such as a glass substrate. In the display region 110, the counter substrate 102 includes a red color filter layer 172R, a green color filter layer 172G, and a blue color filter layer 172B disposed on an insulating substrate 171. On these color filter layers, a counter electrode 173 is disposed so as to face all the pixel electrodes 131.

  The counter electrode 173 is formed of a light transmissive conductive member such as ITO. An alignment film 174 that aligns the liquid crystal 106 of the liquid crystal layer 104 in a direction substantially perpendicular to the substrate surface of the counter substrate 102 is disposed on the counter electrode 173. The array substrate 101 and the counter substrate 102 are bonded together with an outer edge seal member 103. Examples of the liquid crystal display device according to the above embodiment and liquid crystal display devices according to comparative examples will be described below.

(First embodiment)
Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings. 7 and 8 are cross-sectional views for explaining the configuration of the liquid crystal display device according to the embodiment of the present invention. As shown in FIGS. 7 and 8, the liquid crystal display device according to this embodiment includes a pair of substrates, that is, an array substrate 101 and a counter substrate 102, and a liquid crystal layer 104 sandwiched between the array substrate 101 and the counter substrate 102. And have.

  The array substrate 101 has a light absorption plate AP that absorbs light incident on the liquid crystal layer 104 from the counter substrate 102 side. The counter substrate 102 has an antireflection film ARF that prevents reflection of light on the surface of the counter substrate 102.

  In this liquid crystal display device, the liquid crystal layer 104 has a plurality of layers as shown in FIG. 7 when no voltage is applied. In each layer, the liquid crystal molecules form a predetermined angle θ (hereinafter referred to as a pretilt angle) with respect to the tilt direction vector and the substrate surfaces of the array substrate 101 and the counter substrate 102 and are aligned in substantially the same direction. Distributed. Furthermore, in the adjacent layers, the orientation directions of the liquid crystal molecules are non-parallel.

  That is, as shown in FIG. 7, the plurality of layers in the liquid crystal layer 104 are disposed substantially parallel to the substrate surfaces of the array substrate 101 and the counter substrate 102, and the refractive index between adjacent layers is the substrate. It is different for light incident from a direction that is not substantially orthogonal to the surface.

  Therefore, when light from a direction that is not substantially orthogonal to the substrate surface enters the liquid crystal layer 104 from the counter substrate 102 side of the liquid crystal display device described above, the light is reflected at the boundary surface between the plurality of layers, resulting in a white display state. .

  In addition, when a predetermined voltage is applied to the pixel electrode (not shown) of the array substrate 101 and the counter electrode (not shown) of the counter substrate 102, the liquid crystal molecules are converted into the array substrate 101 and the counter substrate 102 as shown in FIG. It is oriented in a direction substantially perpendicular to the substrate surface. As a result, the refractive indexes of adjacent layers of the liquid crystal layer 104 become substantially equal.

  At this time, the light incident on the liquid crystal layer 104 from the counter substrate 102 side enters the liquid crystal layer 104 without being reflected on the surface of the counter substrate 102 by the antireflection film attached to the surface of the counter substrate 102. The light is absorbed by the light absorbing plate AP of the array substrate 101 without being reflected at the boundary surfaces of the plurality of layers. Then, black display is performed in the display area 110 of the liquid crystal display device.

  Next, a manufacturing method of the liquid crystal display device according to this embodiment will be described below.

    First, on the array substrate 101, TFT elements, signal lines X, scanning lines Y, and the like were formed by a normal TFT process, as in the case of the liquid crystal display device according to this embodiment described above. A spacer having a height of about 5 μm is formed thereon with a photoresist to form the array substrate 101.

  On the other hand, as the counter substrate 102, a color filter is formed by a normal process. On the array substrate 101 and the counter substrate 102, a vertical alignment film material manufactured by JSR Co., Ltd. is printed as a vertical alignment film so as to cover the entire display region, and baked at 180 ° C. for 30 minutes to a film thickness of 600 mm. A vertical alignment film 6 is obtained.

Thereafter, a sealant was screen printed on the periphery of the display area 110 in the array substrate 101, combined with the counter substrate 102, and the array substrate 101 and the counter substrate 102 were bonded together by thermosetting. Thereafter, a liquid crystal exhibiting an alternate tilted phase (SmC _A ) of smectic liquid crystal was injected between the array substrate 101 and the counter substrate 102.

  Therefore, the liquid crystal molecules are distributed in the liquid crystal layer 104 so as to form a plurality of layers, and the orientation direction of the liquid crystal molecules is almost constant in each layer. Further, in the adjacent layers, the tilting directions of the liquid crystal molecules are non-parallel.

  Next, the injection port was closed with an ultraviolet curable resin, a light absorption plate AP was attached to the back side of the array substrate 101, and a liquid crystal display device was manufactured by incorporating a drive circuit.

  When the optical characteristics of the liquid crystal display device formed as described above were evaluated, the reflectance of white display in the liquid crystal display device according to this embodiment was 70% with respect to the standard white plate. Further, the contrast ratio of the liquid crystal display device according to the present embodiment was 30: 1. That is, according to the liquid crystal display device according to this example, it is possible to provide a very bright and high-contrast liquid crystal display device with high display quality.

(Second embodiment)
Next, a liquid crystal display device according to a second example of this embodiment is described. In this example, a liquid crystal display device was formed using a liquid crystal different from that of the first example. That is, the liquid crystal display device according to the present embodiment is similar to the liquid crystal display device according to the first embodiment in that the array substrate 101, the counter substrate 102, and the liquid crystal layer 104 sandwiched between the array substrate 101 and the counter substrate 102 are used. have.

  In this embodiment, antiferroelectric liquid crystal (MHPOBC) is used as the liquid crystal to be the liquid crystal layer 104. Since the liquid crystal display device according to the present embodiment is the same as the first embodiment except for the above, the same portions are denoted by the same reference numerals and the description thereof is omitted.

  When the display state of the liquid crystal display device according to this example was evaluated, the reflectance of white display was 65% with respect to a standard white plate, and the contrast ratio was 25: 1. That is, according to the liquid crystal display device according to the present embodiment, it is possible to provide a very bright and high-contrast liquid crystal display device with high display quality.

(First comparative example)
Next, a liquid crystal display device according to a first comparative example of the present invention will be described. As shown in FIG. 9, the liquid crystal display device according to this comparative example was formed using a liquid crystal different from the first example. That is, in this comparative example, a liquid crystal exhibiting a smectic C phase (SmC) was used as the liquid crystal to be the liquid crystal layer 104. Except for this, the liquid crystal display device according to the first embodiment is the same as the liquid crystal display device described above.

  In the liquid crystal display device formed as described above, the liquid crystal molecules are distributed in the liquid crystal layer 104 so as to form a plurality of layers in which the alignment of the liquid crystal molecules is aligned, as in the first embodiment. However, when a liquid crystal exhibiting a smectic C phase is used, the orientation directions of the liquid crystal molecules are parallel in a plurality of layers in the liquid crystal layer 104. Therefore, the refractive index of the adjacent layer is the same whether the voltage is applied to the liquid crystal layer 104 or not, and the difference in refractive index between the adjacent layers is controlled by the electric field. I can't do it.

  Therefore, in the liquid crystal display device described above, the display state of the display region 110 remains black regardless of whether the voltage is applied to the pixel electrode 131 and the counter electrode 173 or not. .

(Second comparative example)
Next, a liquid crystal display device according to a second comparative example of the present invention will be described. The liquid crystal display device according to this comparative example was formed by changing the height of the spacers from the liquid crystal display device according to the first example. That is, as the liquid crystal display device according to this comparative example, six types of liquid crystal display devices having a liquid crystal layer 104 thickness of 1 μm, 2 μm, 3 μm, 5 μm, 10 μm, and 20 μm were formed. Except for this, since it is the same as the liquid crystal display device according to the first embodiment described above, the same components are denoted by the same reference numerals and description thereof is omitted.

  The results of measuring the reflectance and contrast ratio of these six types of liquid crystal display devices according to this comparative example are shown in FIGS. As shown in FIGS. 10 and 11, in the liquid crystal display device in which the thickness of the liquid crystal layer 104 is 3 μm or more, good reflectance and contrast are obtained.

That is, when a liquid crystal exhibiting an alternating tilted phase (SmC _A ) of smectic liquid crystal is used, when the thickness of the liquid crystal layer 104 is 3 μm or more, the light incident on the liquid crystal layer 104 is not reflected at the first boundary surface. Even if there is transmitted light, it can be reflected at the next boundary. Further, even if there is light transmitted without being reflected at the boundary, it can be reflected at the next boundary surface. As described above, since there are a plurality of boundary surfaces in the liquid crystal layer 104, incident light can be efficiently reflected.

  Therefore, when the thickness in the liquid crystal layer 104 is 3 μm or more, good reflectance and contrast can be obtained. As a result, since sufficient brightness and contrast can be obtained without increasing the thickness of the liquid crystal layer 104, it is not necessary to increase power consumption.

(Third comparative example)
Next, a liquid crystal display device according to a third comparative example of the present invention will be described. As the liquid crystal display device according to this comparative example, the liquid crystal display device according to the first embodiment is different from the liquid crystal display device according to the first embodiment in that the pretilt angle of the liquid crystal molecules included in the liquid crystal layer 104 is 5 ° by rubbing the alignment film 6 with various strengths. Six types of liquid crystal display devices of 10 °, 15 °, 45 °, 60 °, and 75 ° were formed.

  Since the liquid crystal display device according to this comparative example is the same as the liquid crystal display device according to the first embodiment except for the above, the same components are denoted by the same reference numerals and description thereof is omitted.

  The results of measuring the reflectance and contrast of these six types of liquid crystal display devices are shown in FIGS. As shown in FIGS. 12 and 13, in the liquid crystal display device in which the pretilt angle of the liquid crystal molecules is in the range of 15 ° to 75 °, good reflectance and contrast were obtained.

  That is, from the evaluation results of the liquid crystal display devices according to the above-described examples and comparative examples, the liquid crystal display device according to the liquid crystal display device according to the present embodiment can obtain a sufficient brightness and low power consumption. An apparatus can be provided.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.

  Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

1 is a perspective view illustrating an example of a liquid crystal display device according to an embodiment of the present invention. FIG. 3 is a diagram for explaining a configuration example of a liquid crystal display device shown in FIG. 1. Sectional drawing for demonstrating one structural example of the liquid crystal display device of the liquid crystal display device shown in FIG. Sectional drawing for demonstrating the structural example of the array substrate of the liquid crystal display device shown in FIG. FIG. 3 is a diagram for explaining an example of a display state in a state where no voltage is applied to the liquid crystal layer of the liquid crystal display device shown in FIG. 1. FIG. 2 is a diagram for explaining an example of a display state in which a voltage is applied to a liquid crystal layer of the liquid crystal display device illustrated in FIG. 1. FIG. 3 is a diagram showing an example of a cross section in a state where no voltage is applied to the liquid crystal layer of the liquid crystal display device according to the first embodiment of the liquid crystal display device shown in FIG. 1. FIG. 2 is a diagram showing an example of a cross section in a state where a voltage is applied to a liquid crystal image of the liquid crystal display device according to the first embodiment of the liquid crystal display device shown in FIG. 1. The figure for demonstrating an example of the evaluation result of six types of liquid crystal display devices which concern on the 2nd comparative example of the liquid crystal display device shown in FIG. FIG. 6 is another view for explaining an example of evaluation results of six types of liquid crystal display devices according to a second comparative example of the liquid crystal display device shown in FIG. 1. The figure for demonstrating an example of the evaluation result of six types of liquid crystal display devices which concern on the 3rd comparative example of the liquid crystal display device shown in FIG. FIG. 9 is another view for explaining an example of evaluation results of six types of liquid crystal display devices according to a third comparative example of the liquid crystal display device shown in FIG. 1.

Explanation of symbols

  101 ... Array substrate, 102 ... Counter substrate, 104 ... Liquid crystal layer

Claims (5)

A pair of substrates facing each other;
A liquid crystal display device having a plurality of layers made of a refractive index anisotropic medium sandwiched between the pair of substrates and oriented in the same direction,
The plurality of layers are arranged substantially parallel to the substrate surfaces of the pair of substrates, and the refractive index difference between adjacent layers is controlled by an electric field,
One of the pair of substrates is a liquid crystal display device having a light absorption plate that absorbs light incident on the liquid crystal layer.   The liquid crystal display device according to claim 1, wherein the plurality of layers are composed of alternating inclined phases of ferroelectric liquid crystal.   The liquid crystal display device according to claim 1, wherein the plurality of layers are made of antiferroelectric liquid crystal.   The liquid crystal display device according to claim 1, wherein an angle formed between a tilt direction of liquid crystal molecules included in each of the plurality of layers and a substrate surface is 15 ° to 75 °.   The liquid crystal display device according to claim 1, wherein the liquid crystal layer has a thickness of 3 μm or more.

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