JPH11288008A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection-type liquid crystal display element which is superior in bi stability, whose characteristic such as color purity is satisfactory, whose contract is high and in which red color balance is not lost even in full color display. SOLUTION: A reflection-type liquid crystal display element where a liquid crystal composition 21 which shows a coresteric phase at a room temperature and whose selected reflection wavelength is adjusted within the range of 690-710 nm is sandwiched by substrates 11 and 12 where ITO electrodes 13 and 14 are formed is provided. The liquid crystal composition 21 is mainly constituted of a kiral nematic liquid crystal component that is mainly composed of at least one compound selected from a ground formed of liquid crystal line tolan compound, liquid crystal line pyrimidine compound, liquid crystal line ester compound and liquid crystal line cyanobiphenyl compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a bistable / reflective liquid crystal display device using a liquid crystal exhibiting a cholesteric phase at room temperature.

[0002]

2. Description of the Related Art In recent years, various researches have been made on reflection type liquid crystal display devices using a chiral nematic liquid crystal which shows a cholesteric phase at room temperature by adding a chiral material to the nematic liquid crystal. In this element, display is performed by switching the liquid crystal between a planar state and a focal conic state by turning on and off the voltage.

However, to date, a reflection type liquid crystal display device using a chiral nematic liquid crystal has not been able to obtain sufficient contrast between the planar state and the focal conic state, and has sufficiently satisfied characteristics such as color purity. What did not exist. In particular, this problem was remarkable in a reflection type liquid crystal display element conventionally used for red display. Further, such a reflective liquid crystal display device for red display has a large viewing angle dependency, and has a problem that the color tone changes depending on the angle at which the display device is observed. Therefore, when elements for displaying each color such as red, green, and blue are stacked for full-color display, there is also a problem that the red color balance is lost.

Accordingly, an object of the present invention is to provide a reflection type liquid crystal which is excellent in bistability, has good characteristics such as color purity, has high contrast, and does not lose the red color balance even in a full color display. It is to provide a display element.

[0005]

In order to achieve the above objects, a liquid crystal display device according to the present invention exhibits a cholesteric phase at room temperature between a pair of transparent substrates, and has a selective reflection wavelength of 690. The liquid crystal composition adjusted within the range of ７710 nm is sandwiched.

According to the present invention, a chiral nematic liquid crystal exhibiting a cholesteric phase at room temperature has a selective reflection wavelength of 6
Since the adjustment is performed within the range of 90 to 710 nm, a reflective liquid crystal display device having good color purity and high contrast can be obtained. In particular, the viewing angle dependency of red is reduced, and reproducibility is improved. Further, when each element for red reflection, green reflection, and blue reflection is stacked to display full color, the color balance of red is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the liquid crystal display device according to the present invention will be described with reference to the accompanying drawings.

(Configuration and Display Operation of First Embodiment) FIG. 1 shows a sectional structure of a liquid crystal display element according to a first embodiment of the present invention. (A) shows a planar state (RGB colored state) when a high voltage pulse is applied, and (B) shows a focal conic state (transparent / black display state) when a low voltage pulse is applied.

In FIG. 1, reference numerals 11 and 12 denote transparent substrates.
On each surface, transparent electrodes 13 and 14 are formed in a matrix. It is preferable that an insulating thin film 15 is coated on the electrode 13. The substrate 12
The visible light absorbing layer 16
Is provided. Reference numeral 20 denotes a columnar structure, and reference numeral 21 denotes a liquid crystal composition exhibiting a cholesteric phase at room temperature. These materials and combinations thereof will be described below, and further specifically described by the following experimental examples. Reference numeral 24 denotes a sealant for sealing the liquid crystal composition 21 between the substrates 11 and 12. Reference numeral 25 denotes a pulse power supply,
A predetermined pulse-like voltage is applied to 3,14.

In the liquid crystal display device having the above configuration, display is performed by applying a pulse voltage from the power supply 25 to the electrodes 13 and 14. That is, when the liquid crystal composition uses a cholesteric phase, by applying a relatively high pulse voltage, the liquid crystal is in a planar state,
Light of a wavelength determined based on the cholesteric pitch and the refractive index is selectively reflected. By applying a relatively low pulse voltage, the liquid crystal is in a focal conic state and is in a transparent state. When the visible light absorbing layer 16 is provided as shown in FIG. 1, black is displayed in the focal conic state.

In the present liquid crystal display device, a matrix electrode 1
The area where 3 and 14 intersect is the display pixel. In this specification, a region where light modulation is performed by liquid crystal is referred to as a display region, and its periphery is outside the display region where light modulation is not performed.

(Substrate) At least one of the substrates 11 and 12 needs to be transparent. As a transparent substrate,
In addition to glass, flexible substrates such as polycarbonate, polyethersulfone, and polyethylene terephthalate can be used.

(Electrode) The electrodes 13 and 14 are made of ITO.
A transparent conductive film represented by (Indium Tin Oxide), a metal electrode such as aluminum or silicon, or a photoconductive film such as amorphous silicon or BSO (Bismuth Silicon Oxide) can be used. In order to form the electrodes 13 and 14 in a matrix, for example, an ITO film may be formed on the substrates 11 and 12 by a sputtering method and then patterned by a photolithography method.

(Insulating Film, Alignment Film) The insulating thin film 15 is an inorganic film such as silicon oxide or an organic film such as a polyimide resin or an epoxy resin, and prevents a short circuit between the electrodes 13 and 14 and a liquid crystal as a gas barrier layer. It has the function of improving the reliability of Further, an alignment film typified by a polyimide resin may be provided on the electrodes 13 and 14 as needed. Further, the same material as the polymer used for the columnar structure 20 may be used as the insulating film or the alignment film.

(Spacer) Although not shown in FIG. 1, a spacer may be inserted between the substrates 11 and 12. This spacer is a sphere made of resin or inorganic oxide, and
The gap between 1 and 12 is kept uniform.

(Liquid crystal composition) The liquid crystal composition is a nematic containing as a main component at least one compound selected from the group consisting of a liquid crystalline tolan compound, a liquid crystalline pyrimidine compound, a liquid crystalline ester compound and a liquid crystalline cyanobiphenyl compound. A liquid crystal containing a chiral material so as to exhibit a cholesteric phase at room temperature is used.
A coloring pigment may be added.

According to the study of the present inventors, it has been found that setting the selective reflection wavelength of the reflection type liquid crystal display device in an appropriate wavelength range is important for the display characteristics of the device.
As a result of various studies, the present inventors have found that the selective reflection wavelength was around 680 nm in the conventional reflective liquid crystal display device for red display, but by setting this to a range of 690 to 710 nm, the dual reflection wavelength was reduced. It has been found that the viewing angle dependency can be reduced while maintaining good stability and color purity. From such a viewpoint, the liquid crystal composition used for the display element of the present embodiment is prepared so that the selective reflection wavelength is in the range of 690 to 710 nm. The selective reflection wavelength may be adjusted by changing the amount of the chiral material added. Generally, as the amount of the chiral material added increases, the selective reflection wavelength shifts to the shorter wavelength side. In addition, the selective reflection wavelength refers to the electrode 1
The peak wavelength in the visible light region of the reflected light spectrum when a pulse voltage is applied to the liquid crystals 3 and 14 to bring the liquid crystal into a planar state.

As the chiral material to be added, various known chiral materials such as an ester compound, a pyrimidine compound, an azoxy compound and a tolan compound can be used. The addition amount is preferably 5 to 30% by weight based on the liquid crystal component. If it is less than 5 wt%, a desired selective reflection wavelength may not be realized, and if it is more than 30 wt%, a cholesteric phase may not be exhibited at room temperature.

As the dye to be added, various conventionally known dichroic dyes can be used. The addition amount is preferably 3% by weight or less based on the total amount of the liquid crystal component and the chiral material.

(Pillar Structure) First, the structure of the pillar structure 20 will be described. Columnar structure 20
Are, for example, a columnar body, a square columnar body, and an elliptical columnar body arranged at a predetermined interval in a predetermined pattern such as a lattice arrangement. Stripes arranged at predetermined intervals may also be used. The columnar structures 20 are not arranged at random, but are arranged at equal intervals, an array in which the intervals gradually change, and an array in which a predetermined arrangement pattern is repeated at a constant period.
It is preferable that the arrangement is such that the twelve gaps can be appropriately maintained and the image display is not disturbed. If the columnar structure 20 has an area ratio of 1 to 40% in the display region, practically sufficient characteristics as a display element can be obtained while maintaining sufficient strength.

Next, the materials will be described. The columnar structure 20 is formed using a polymerizable composition obtained by adding a polymerization initiator to a polymerizable monomer (monomer). As the polymerizable composition, for example, a commercially available photocurable resin material composed of a mixture of a photocurable monomer or oligomer and a photopolymerization initiator can be used. When the photocurable resin material is irradiated with light and polymerized to form a columnar structure, it is easy to arrange the columnar structure at a predetermined shape and at an interval.
Particularly suitable as a material constituting the columnar structure is an acrylate compound as a main component. The acrylate ester is an acrylate compound or a methacrylate compound having two or more allyl groups, and a structure such as an aromatic ring may be included on the main chain between the allyl groups. 2 of CO, CO ₂ , CH ₂ , O, etc.
A valent group may be included. The acrylate compound also includes an epoxy acrylate compound, a urethane acrylate compound, and the like.

Next, a method of manufacturing the columnar structure 20 will be described. First, an ultraviolet curable compound (column structure composition) is sandwiched between a substrate on which an ITO electrode is formed and a mask on which a predetermined pattern is formed, or an ultraviolet curable compound is applied on the electrode surface of the substrate. Then, a mask is covered, and this is irradiated with ultraviolet rays. Next, the mask is peeled off, the unexposed portion of the compound is washed with a predetermined solvent, dried and cured.

After a mixture of a liquid crystal material and a photocurable resin material is sandwiched between glass substrates in advance, a photomask is placed on the glass substrates and light irradiation is performed to perform polymerization phase separation, thereby forming columnar structures. It is also possible to form. In order to form a liquid crystal display element, a liquid crystal composition may be injected between substrates sandwiching the columnar structure by a vacuum injection method or the like.

(Configuration of Second Embodiment) FIG. 2 shows a cross-sectional structure of a liquid crystal display device according to a second embodiment of the present invention.
(A) shows a planar state (RGB colored state) when a high voltage pulse is applied, and (B) shows a focal conic state (transparent / black display state) when a low voltage pulse is applied.

This liquid crystal display element is of a network type in which a network-like composite film 22 composed of a chiral nematic liquid crystal composition 21 and a resin composition 23 is formed. The liquid crystal composition 21 is made of the same material as the chiral nematic liquid crystal composition 21 described in the first embodiment. Resin composition 23
Although any material can be used, the same material as that of the columnar structure 20 may be used. Other members are the first
It is the same as the embodiment, and the same reference numerals as in FIG. 1 are assigned.

The composite film 22 is prepared by mixing a liquid crystal composition and a photocurable resin material to which a photopolymerization initiator has been added at a predetermined ratio, and then dropping the mixture on a spacer-coated substrate. After being covered and brought into close contact with each other, the resin material is irradiated with ultraviolet rays to produce a polymerized phase-separated product.

(Configuration of Third Embodiment) FIG. 3 shows a cross-sectional structure (in a planar state when a high voltage pulse is applied) of a liquid crystal display element according to a third embodiment of the present invention. This liquid crystal display element is basically the same as that of the first embodiment shown in FIG. 1, and does not include a columnar structure in a display area. 3, the same members as those in FIG. 1 are denoted by the same reference numerals.

(Configuration of Fourth Embodiment) FIG. 4 shows a cross-sectional structure (in a planar state when a high voltage pulse is applied) of a liquid crystal display element according to a fourth embodiment of the present invention. This liquid crystal display element is the same as that of the third embodiment shown in FIG.
A small columnar structure 20 'extending to an intermediate portion between the gaps 1 and 12.
Is formed. 4, the same members as those in FIGS. 1 and 3 are denoted by the same reference numerals.

(Structure of Fifth Embodiment) FIG. 5 shows a sectional structure of a liquid crystal display device according to a fifth embodiment of the present invention. This liquid crystal display element has a three-layer structure in order to enable full color display, and a red reflection element 10R, a green reflection element 10G, and a blue reflection element 10B are stacked from below. Each of the elements 10R, 10G, and 10B has the same configuration as in the first embodiment shown in FIG. 1, and the same reference numerals are given to the same members in FIG. The power supply 25 applies predetermined pulse voltages V _R , V _G ,
V _B is selectively applied.

(Structure of Sixth Embodiment) In the sixth embodiment, in the liquid crystal display device shown in FIG. 1, a columnar structure is formed by a screen printing method. In the screen printing method, a screen on which a predetermined pattern is formed is placed on an electrode surface of a substrate, and a printing material (column structure composition) is placed on the screen. Then, the squeegee is moved at a predetermined pressure, angle, and speed. This transfers the material onto the substrate via the pattern on the screen. Next, the transferred material is cured by heating and dried.

When the columnar structure is formed by the screen printing method, the resin material is not limited to a photocurable resin, but a thermosetting resin such as an epoxy resin or an acrylic resin or a thermoplastic resin can also be used. Thermoplastic resins include polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polymethacrylate resin, polyacrylate resin, polystyrene resin, polyamide resin, polyethylene resin, polypropylene resin, fluorine resin, and polyurethane resin. And polyacrylonitrile resin, polyvinyl ether resin, polyvinyl ketone resin, polyether resin, polyvinyl pyrrolidone resin, saturated polyester resin, polycarbonate resin, chlorinated polyether resin and the like. It is desirable that the resin material is used in the form of a paste by dissolving the resin in an appropriate solvent.

After arranging the resin material on the substrate, spacers are sprayed on at least one of the substrates, and a pair of substrates are overlapped with the surfaces on which the plurality of strip electrodes are formed facing each other to form an empty cell. After heating a pair of superposed substrates while applying pressure from both sides, the resin material is softened, and then cooled to be solidified again.

(Experimental Example 1) A liquid crystal material containing a liquid crystalline trans compound as a main component (refractive index anisotropy Δn = 0.219, dielectric anisotropy Δε = 8.08, phase transition temperature T _NI = 69. 9
At 20 ° C. and a temperature of 20 ° C. = 30.6 cp), the chiral material CN and S-811 (both manufactured by Merck) were each 21.66 wt%, 3.92 wt%, and the dichroic dye S
0.5 wt% of I-426 (manufactured by Mitsui Toatsu) was mixed to prepare a liquid crystal composition having a selective reflection wavelength of 705 nm.
The above-mentioned chiral nematic liquid crystal composition was applied between glass substrates on which electrodes were formed, and another glass substrate on which electrodes were formed was bonded using a sealing material via a resin spacer having a thickness of 10 μm (see FIG. 3). ). Further, a black light absorbing layer was provided on the substrate on the side opposite to the side where light was incident.

In such a liquid crystal display element, when a pulse voltage of 50 V was applied between the electrodes for 5 msec, the liquid crystal display element showed a transparent state and the Y value was 0.69. In addition, 90V
When a pulse voltage of 5 msec was applied for 5 msec, a red state was exhibited, the Y value was 3.79, and the contrast was 5.49. The color purity is 58 (x = 0.5236, y = 0.3
233) (see FIG. 6). Note that the color purity is defined as a chromaticity point of illumination light serving as a reference (（in FIGS. 6 and 7: x = 0.
306, y = 0.317), the distance between the chromaticity point of the main wavelength on the spectrum locus of the chromaticity coordinates, and the distance between the chromaticity point of the illumination light and the chromaticity point of the liquid crystal display element sample. It shows the ratio. In other words, if the liquid crystal display elements have the same brightness, the color purity is higher (the display quality is higher) when the chromaticity point of the liquid crystal display element is farther from the chromaticity point of the illumination light.
Further, the viewing angle, i.e., with respect to the angle θ of the observation position X with respect to a normal X ₁ at reflection point as shown in FIG. 1, be changed viewing angle was no significant change in the peak position of the reflected spectrum. It was 680 nm even at a viewing angle of 30 °, and remained red. The Y value (luminous reflectance) and the color purity were measured using a reflection type spectrophotometer CM-37 having a white light source.
00d (manufactured by Minolta). The same applies to the following experimental examples and comparative examples.

(Experimental Example 2) A liquid crystal material having a liquid crystal ester compound as a main component (refractive index anisotropy Δn = 0.1787,
Dielectric anisotropy Δε = 30, phase transition temperature T _NI = 100 ° C.,
The viscosity η at 20 ° C. = 58 cp) and the chiral material CB
-15 and R-811 (both manufactured by Merck) at 16.13 wt% and 7.83 wt%, respectively, dichroic dye SI
-426 (manufactured by Mitsui Toatsu) was mixed at 0.5 wt% to prepare a liquid crystal composition having a selective reflection wavelength of 705 nm. The above-mentioned chiral nematic liquid crystal composition was applied between glass substrates on which electrodes were formed, and another glass substrate on which electrodes were formed was bonded using a sealing material via a resin spacer having a thickness of 10 μm (see FIG. 3). ). Further, a black light absorbing layer was provided on the substrate on the side opposite to the side where light was incident.

In such a liquid crystal display element, when a pulse voltage of 30 V was applied between the electrodes for 5 msec, the liquid crystal display element showed a transparent state and the Y value was 0.48. In addition, 60V
When a pulse voltage of 5 msec is applied for 5 msec, a scattered red state is exhibited, the Y value is 6.16, and the contrast is 4.83.
Met. The color purity is 64.09 (x = 0.5376, y
= 0.3341) (see FIG. 6). Regarding the viewing angle, there was no significant change in the peak position of the reflection spectrum even when the viewing angle was changed. 690 even at a viewing angle of 30 °
nm and remained red.

(Experimental Example 3) A liquid crystal material containing a liquid crystalline trans compound as a main component (refractive anisotropy Δn = 0.222, dielectric anisotropy Δε = 10.2, phase transition temperature T _NI = 81. 8
And the chiral material CN and S-811 (both manufactured by Merck) at 18.95 wt%, 4.53 wt%, respectively, and the dichroic dye SI-
426 (manufactured by Mitsui Toatsu) was mixed at 0.5 wt% to prepare a liquid crystal composition having a selective reflection wavelength of 700 nm. The above-mentioned chiral nematic liquid crystal composition was applied between glass substrates on which electrodes were formed, and another glass substrate on which electrodes were formed was bonded using a sealing material via a resin spacer having a thickness of 10 μm (see FIG. 3). ). Further, a black light absorbing layer was provided on the substrate on the side opposite to the side where light was incident.

In such a liquid crystal display element, when a pulse voltage of 30 V was applied between the electrodes for 5 msec, the liquid crystal display element was in a transparent state, and the Y value was 1.12. In addition, 80V
When a pulse voltage of 5 msec is applied, a scattering red state is exhibited, the Y value is 4.18, and the contrast is 3.73.
Met. The color purity is 53 (x = 0.5228, y = 0.
3312) (see FIG. 6). Regarding the viewing angle, there was no significant change in the peak position of the reflection spectrum even when the viewing angle was changed. It was 682 nm even at a viewing angle of 30 °, and remained red.

(Experimental Example 4) A liquid crystal material containing a liquid crystalline trans compound as a main component (refractive anisotropy Δn = 0.23, dielectric anisotropy Δε = 12.6, phase transition temperature T _NI = 89. 7 ° C,
The viscosity η at 20 ° C. = 37.8 cp) was mixed with 19.66 wt% and 3.92 wt% of chiral materials CB-15 and R-811 (both manufactured by Merck Co., Ltd.), and the selective reflection wavelength was 695 nm. Liquid Crystal Composition No. 1 was prepared. Further, a chiral material CB-15 and R-811 (both manufactured by Merck Ltd.) were added to the liquid crystal material mainly containing the liquid crystal trans compound at 18.8 wt% and 7.1 w, respectively.
% liquid, and a second liquid crystal composition having a selective reflection wavelength of 480 nm was prepared. Further, a chiral material CB-15 and R-811 (both manufactured by Merck Ltd.) were added to the liquid crystal material mainly containing the liquid crystal trans compound at 13.5, respectively.
wt%, 4.9wt%, and the selective reflection wavelength is 550n
m was prepared. As shown in FIG. 5, these three types of liquid crystal compositions were applied to a glass substrate on which electrodes were formed, and bonded together with a sealing material via a 10 μm-thick resin spacer.
Reflection layers of 50 nm and 480 nm were formed. further,
A black light-absorbing layer was provided on the substrate on the side opposite to the side where light was incident.

In such a liquid crystal display element, a pulse voltage of 40 V is applied for 5 ms between the electrodes of the lowermost element 10R.
When ec was applied, the transparent state was exhibited, and the Y value was 0.78. Further, when a pulse voltage of 90 V was applied for 5 msec, a red state was exhibited, the Y value was 3.72, and the contrast was 4.77. The color purity is 55 (x = 0.5
250, y = 0.3249) (see FIG. 6). In addition, as shown in FIG.
The area connecting the chromaticity points of the red, green, and blue display parts on the chromaticity diagram is larger than that of the full-color liquid crystal display element using the red display element as a red display element. It can be seen that the color balance is good. Regarding the viewing angle, there was no significant change in the peak position of the reflection spectrum even when the viewing angle was changed. 6 even with a viewing angle of 30 °
88 nm and remained red.

(Comparative Example 1) Chiral materials CN and S-811 (both manufactured by Merck Co., Ltd.) were added at 16 wt% and 8 wt%, respectively, to the same liquid crystal material mainly composed of the liquid crystalline trans compound used in Experimental Example 1. 0.5% by weight of dichroic dye SI-426 (manufactured by Mitsui Toatsu Co., Ltd.) and the selective reflection wavelength is 6%.
A liquid crystal composition exhibiting 70 nm was prepared. The above-mentioned chiral nematic liquid crystal composition was applied between glass substrates on which electrodes were formed, and another glass substrate on which electrodes were formed was bonded using a sealing material via a resin spacer having a thickness of 10 μm (see FIG. 3). ). Further, a black light absorbing layer was provided on the substrate on the side opposite to the side where light was incident.

In such a liquid crystal display element, when a pulse voltage of 70 V was applied between the electrodes for 5 msec, the liquid crystal display element was in a transparent state, and the Y value was 3.36. In addition, 110
When a pulse voltage of V was applied for 5 msec, a red state was exhibited, the Y value was 6.9, and the contrast was 2.05. The color purity is 48 (x = 0.4589, y = 0.31)
76) (see FIGS. 6 and 7). Regarding the viewing angle, when the viewing angle was changed, the reflection spectrum was shifted to the lower wavelength side, and the reflection spectrum was observed in a yellowish color. Incidentally, it was 630 nm at a viewing angle of 30 °.

Comparative Example 2 A liquid crystal material containing a liquid crystalline cyanobiphenyl compound as a main component (refractive index anisotropy Δn = 0.2
810, dielectric anisotropy Δε = 15.5, phase transition temperature T _NI
= 108 ° C., 20 ° C., viscosity η = 83 cp) and chiral materials CB-15 and R-811 (both manufactured by Merck) at 16.4 wt% and 8.54 wt%, respectively, and dichroic dye SI-426 ( (Mitsui Toatsu Co., Ltd.) was mixed at 0.5 wt% to prepare a liquid crystal composition having a selective reflection wavelength of 670 nm. The above-mentioned chiral nematic liquid crystal composition was applied between glass substrates on which electrodes were formed, and another glass substrate on which electrodes were formed was bonded using a sealing material via a resin spacer having a thickness of 10 μm (see FIG. 3). ). Further, a black light absorbing layer was provided on the substrate on the side opposite to the side where light was incident.

In such a liquid crystal display element, when a pulse voltage of 60 V was applied between the electrodes for 5 msec, the liquid crystal display element was in a transparent state, and the Y value was 2.76. In addition, 100
When a pulse voltage of V was applied for 5 msec, a red state was exhibited, the Y value was 6.06, and the contrast was 2.20. The color purity was 22.6 (x = 0.4078, y =
0.3150) (see FIGS. 6 and 7). Regarding the viewing angle, when the viewing angle was changed, the reflection spectrum was shifted to the lower wavelength side, and the reflection spectrum was observed in a yellowish color. Incidentally, it was 667 nm at a viewing angle of 30 °.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a liquid crystal display device according to the present invention, wherein (A) shows a planar state and (B) shows a focal conic state.

2A and 2B are cross-sectional views illustrating a liquid crystal display device according to a second embodiment of the present invention, wherein FIG. 2A shows a planar state, and FIG. 2B shows a focal conic state.

FIG. 3 is a sectional view showing a third embodiment of the liquid crystal display device according to the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the liquid crystal display device according to the present invention.

FIG. 5 is a sectional view showing a fifth embodiment of the liquid crystal display device according to the present invention.

FIG. 6 is a chromaticity diagram showing color reproducibility of an experimental example and a comparative example.

FIG. 7 is a chromaticity diagram showing the color balance of an experimental example and a comparative example.

[Explanation of symbols]

 11, 12 ... substrate 13, 14 ... electrode 15 ... insulating thin film 16 ... visible light absorbing layer 20, 20 '... columnar structure 21 ... liquid crystal composition 22 ... composite film 23 ... resin composition 25 ... power supply

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1347 G02F 1/1347 1/137 1/137 1/137

Claims (4)

[Claims] 1. A liquid crystal composition exhibiting a cholesteric phase at room temperature and having a selective reflection wavelength adjusted within a range of 690 to 710 nm is sandwiched between a pair of substrates at least one of which is transparent. Liquid crystal display device. 2. The chiral nematic comprising at least one compound selected from the group consisting of a liquid crystalline tolan compound, a liquid crystalline pyrimidine compound, a liquid crystalline ester compound, and a liquid crystalline cyanobiphenyl compound, and a chiral material. 2. The liquid crystal display device according to claim 1, wherein a liquid crystal component is a main component. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal composition contains a dichroic dye. 4. The liquid crystal display device for red reflection according to claim 1, wherein a display device containing a chiral nematic liquid crystal component for green reflection and a display device containing a chiral nematic liquid crystal component for blue reflection are stacked. Full color liquid crystal display device.