JP3092564B2 - Liquid crystal optical element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal optical element used for a display device for displaying characters and figures, a light control device for changing the wavelength or the amount of reflected light or transmitted light, or an optical shutter. More particularly, the present invention relates to a liquid crystal optical element that selectively reflects a specific wavelength band.

[0002]

2. Description of the Related Art A conventional liquid crystal display device has a structure in which a holographic polymer dispersed liquid crystal element (hereinafter referred to as HPDLC) is laminated as a high-brightness reflective display. The HPDLC element includes a multi-layer light control layer in which a layer mainly made of a liquid crystal material and a layer made of a transparent resin are sequentially laminated, and the light control layer is sandwiched between substrates with transparent electrodes. . When the refractive index of the liquid crystal material is set to be different from the refractive index of the transparent resin when no voltage is applied, a periodic refractive index difference occurs in the light control layer, and the refractive indices of the liquid crystal material and the transparent resin are different. Light in a specific wavelength band defined by the distance between the layers and the multilayer structure is reflected, and light in other wavelength bands is transmitted. In addition, when the refractive index difference between the liquid crystal material and the transparent resin is set to be small by applying a voltage to the light control layer, the reflectance of light in a specific wavelength band is greatly reduced, and the element becomes transparent. Show. As described above, in the HPDLC element, the light reflectance in a specific wavelength band can be controlled by the voltage, and natural light incident on the liquid crystal optical element is used as a light source for display. Therefore, a backlight is not required.
However, to control only the reflectance of light in a specific wavelength band,
Multicolor display is not possible with only one light control layer.

[0003] Japanese Patent Application Laid-Open No. 6-294952 discloses a liquid crystal display device having a multicolor structure. FIG.
FIG. 1 is a cross-sectional view schematically illustrating a liquid crystal optical element of a liquid crystal display device described in the publication. In this liquid crystal optical element, dimming layers 27, 28, and 29, which reflect the three primary colors of light, blue, red, and green, and have the same area and layer thickness, are sandwiched between transparent substrates 26 with transparent electrodes. Consists of
By controlling the reflected light of each color, multi-coloring by an apparent single surface (pixel) is achieved. In the figure, 17 is incident light, 18B, 18R, and 18G are blue, respectively.
Red and green reflected light, 25 is a light absorbing layer.

[0004]

In the above-mentioned conventional liquid crystal optical element, dimming layers having different wavelength bands of reflected light are laminated, thereby enabling multicolor display on an apparent single plane. Since the light reflection intensity differs for each light control layer, good color balance of display colors cannot be obtained. The overall light reflection intensity of the multilayer structure having the above-described refractive index difference depends on the magnitude of the refractive index difference and the number of layers. For example, in the case where the difference in refractive index is 0.2 and the light reflection efficiency is to be 90% or more, it is necessary to alternately provide as many as 60 or more layers with high and low refractive indexes.

[0005] Further, since the hue and light intensity (visual characteristics) of each color perceived by a human depend on the wavelength of light, the above-mentioned conventional light-modulating layer in which pixel areas have the same area and layer thickness on the viewing surface side is laminated. In the liquid crystal optical element described above, the intensity and the visual characteristics of the reflected light of each light control layer differ depending on the wavelength, and it is difficult to display a target color in a well-balanced manner. FIG. 8 is a graph showing the correlation between the wavelength of the incident light 17 and the reflected light of each color in this case. From this graph, it can be seen that the reflectances of blue, red, and green are significantly different from each other, and the color balance is poor.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a liquid crystal optical element having a wide color range of display colors and a good color balance, and in particular, a white color to be displayed when no voltage is applied, without coloring. .

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, if the volume of the pixel portion of the light control layer to be laminated is adjusted for each light control layer, the color It has been found that a liquid crystal optical element having a good balance and, in particular, a white color to be displayed when no voltage is applied is not colored.

That is, in order to achieve the above object, a liquid crystal optical element according to the present invention is a reflection type liquid crystal optical element comprising a light control layer in which a liquid crystal material is layered and regularly arranged in a transparent resin. A plurality of liquid crystal display elements sandwiched between electrode layers are stacked and provided, and each light control layer reflects a specific wavelength band in a visible light region, and the volume of a pixel portion is different from each other. At least one of the layer thickness of the effective display portion and the area of the pixel portion in the light control layer on the viewing surface side is different for each liquid crystal display element.

According to the present invention, light control layers having different pixel volumes are alternately stacked, so that the light reflection intensity of the color reflected by each light control layer can be controlled, and the color balance can be improved. It is possible to obtain a liquid crystal optical element which is good and is not colored white, which is displayed when no voltage is applied. In addition, since the area of the pixel portion on the viewing surface side and / or the layer thickness of the effective display portion are made different for each light control layer, it is possible to control the drive voltage of each light control layer without breaking the color balance. become.

[0010]

Further, it is preferable that a plurality of liquid crystal display elements are respectively connected to the corresponding active elements. In addition, it is preferable that the ordinary light refractive index of the liquid crystal material matches the refractive index of the transparent resin, and the dimming layer enters a light reflecting state when no voltage is applied, and the intensity of reflected light decreases as the applied voltage increases. . In this case, by arbitrarily controlling only the drive voltage of each light control layer while maintaining the color tone and light reflection intensity of each light control layer, the drive waveform can be simplified without breaking the color balance.

In the present invention, the light modulating layer comprising a transparent resin and a liquid crystal material irradiates a mixture containing at least a precursor compound of the transparent resin, a liquid crystal material, and a polymerization initiator with light to form a transparent resin. It can be produced by polymerizing a precursor compound to form a transparent resin. Further, the laminated structure of the transparent resin layer and the liquid crystal material layer, a mixed solution containing at least a precursor compound of the transparent resin, a liquid crystal material and a polymerization initiator,
It can be produced by irradiating a laser beam or the like having the same phase with the two-beam interference method and polymerizing a precursor of the transparent resin. The wavelength and intensity of the light that is selectively reflected can be adjusted by the layer spacing between the transparent resin layer and the liquid crystal material layer, and the refractive index difference between the transparent resin and the liquid crystal material layer. Apparent 1
To perform multi-color display with pixels, there are three light control layers: a light control layer that selectively reflects red light, a light control layer that selectively reflects green light, and a light control layer that selectively reflects blue light. Stack the layers. The order of the light control layers to be laminated is not limited.

For the purpose of displaying a multicolor by additive mixing of each of the three primary colors of light (red, blue, and green), the number of laminated light control layers is such that at least the wavelength band of those colors is reflected. Three light control layers are stacked, but 3
More than two layers may be stacked. Further, a light control layer that reflects a wavelength band of a color other than the three primary colors of light can be laminated.

The volume of each pixel portion of the light control layer is the volume of the portion where the amount of transmitted light changes in response to a voltage when a voltage is applied to the pixel. As a method of changing the volume of each pixel part, a method of changing the area of the pixel part while keeping the layer thickness of the light control layer constant may be used. May be changed. Further, a method of simultaneously changing both the area and the layer thickness of the pixel portion may be employed.

The area of each pixel portion of the light control layer is the area on the viewing surface side of the portion where the amount of transmitted light changes in response to an electric field when a voltage is applied to the pixel. When the thickness of each light control layer is equal, the area of each pixel portion of the light control layer that reflects red light is preferably 0.5 times or more and 2 times or less the area of the pixel portion that reflects blue light, Desirably 0.8 times or more and 1.5
Less than twice. Further, the area of the pixel portion that reflects green light is desirably 0.5 times or more and 2 times or less the thickness of the light control layer that reflects blue light. In an element having an area exceeding the range of these relationships, good color balance is impaired,
In particular, the white color displayed when no voltage is applied is colored.

The thickness of the light control layer is preferably 3 to 20 μm.
When the thickness of the light control layer is 3 μm or less, the display image becomes dark because the light reflection intensity becomes weak, and when the thickness is more than 20 μm, the driving voltage increases and power consumption increases. When the effective display volumes of the respective pixel portions are equal, the layer thickness of the light control layer that reflects red light is preferably 0.5 times or more and 2 times or less the layer thickness of the light control layer that reflects blue light. , Desirably 0.8 or more and 1.5 times or less. The thickness of the light control layer that reflects green light is preferably 0.5 times or more and 1.5 times or less the thickness of the light control layer that reflects blue light. In a device having a layer thickness exceeding these ranges, good color balance is impaired, and white displayed in particular when no voltage is applied is colored.

In the present invention, the refractive index of the transparent resin, that is, the transparent resin obtained by polymerizing the precursor compound of the transparent resin, is the same as the ordinary light refractive index (no) of the liquid crystal material, or Set so that they are close to each other. The liquid crystal material in the liquid crystal layer is randomly oriented when no voltage is applied. Therefore, in the light control layer, since a layer having a refractive index difference composed of the liquid crystal layer and the transparent resin layer is periodically present, Bragg reflection occurs, and light having a wavelength corresponding to the layer interval and the refractive index difference is generated. Can be selectively reflected. On the other hand, when no voltage is applied, as the voltage increases, the refractive index of the liquid crystal material approaches the refractive index of the transparent resin, so that the intensity of the reflected light decreases.

As the precursor compound of the transparent resin, a monomer or oligomer polymerizable by light irradiation, or a mixture of a monomer and an oligomer can be used. That is, any precursor compound having a usual photopolymerizable group such as an acryloyl group, a methacryloyl group, and a vinyl group can be used.

A plurality of photopolymerizable groups may be present in one molecule of the precursor compound. Examples of the monomer include 2-ethylhexyl acrylate, butylethyl acrylate, butoxyethyl acrylate, 2-cyanoethyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-hydroxypropyl acrylate,
-Ethoxyethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, isobonyl acrylate, isodecyl acrylate, lauryl Acrylate, morpholine acrylate, phenoxyethyl acrylate, monofunctional acrylate compounds such as phenoxydiethylene glycol acrylate, 2-ethylhexyl methacrylate, butylethyl methacrylate,
There are polyfunctional methacrylate compounds such as butoxyethyl methacrylate, 2-cyanoethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 2-hydroxypropyl methacrylate, and 2-ethoxyethyl acrylate.

As the monomer, for example, N, N-
Diethylaminoethyl methacrylate, N, N-dimethylaminoethyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, isobonyl methacrylate, isodecyl methacrylate, lauryl methacrylate, morpholine methacrylate, phenoxyethyl methacrylate, Monofunctional methacrylate compounds such as phenoxydiethylene glycol methacrylate, diethylene glycol diacrylate, 1,4-butanediol diacrylate,
1,3-butylene glycol diacrylate, dicyclopentanyl diacrylate, glycerol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetra There are polyfunctional methacrylate compounds such as acrylate, pentaerythritol triacrylate, and ditrimethylolpropane tetraacrylate.

Further, examples of the monomer include polyfunctional acrylate compounds such as dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, and urethane acrylate oligomer;
Diethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, dicyclopentanyl dimethacrylate glycerol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tetraethylene glycol There are polyfunctional methacrylate compounds such as dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, pentaerythritol trimethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol monohydroxypentamethacrylate, and urethane methacrylate oligomer. But limited to these Not intended to be.

The precursor compound of the transparent resin is formed by a polymerization initiator for initiating polymerization by light irradiation, a photopolymerization initiation aid for supplying protons or the like to the photopolymerization initiator, and a light-absorbing agent. A dye sensitizer that transfers excitation energy to the photopolymerization initiator can be added. However, when the polymerization is initiated by light irradiation with the photopolymerization initiator alone, other materials need not be added. As the photopolymerization initiator, acetophenone-based, benzoin-based, benzophenone-based, and thioxanthone-based photopolymerization initiators can be used. Examples of the photopolymerization initiator include diethoxyacetophenone, dimethoxyacetophenone, benzoin methyl ether, bezoin ethyl ether, 4-phenylbenzophenone, 2-chlorothioxanthone, and 2-methylthioxanthone. The photopolymerization initiator may be a solid or a liquid, but is desirably soluble or compatible at room temperature in a liquid mixture of a liquid crystal material and a transparent resin precursor from the viewpoint of the uniformity of the device. The addition amount of the photopolymerization initiator is desirably 30% by weight or less of the transparent resin precursor.

As the photopolymerization initiation aid, general photopolymerization initiation aids such as methyldiethanolamine and 4-dimethylaminobenzoic acid can be used.

In the present invention, as a dye sensitizer, coumarin dye, rhodamine dye, oxazine dye, carbocyanine dye, styryl dye, xanthene dye,
Examples include, but are not limited to, merocyanine dyes, rhodocyanine dyes, porphyrin dyes, and acridine dyes. Any dye sensitizer may be used as long as it is excited by light irradiation and can transfer energy to the photopolymerization initiator.

As a light source used for photopolymerization of the precursor of the transparent resin, a visible laser beam can be used. Photopolymerization by laser light is performed by a two-beam interference method. That is, the laser light divided into two by the beam splitter is incident so as to intersect at the position of the light control layer, and photopolymerization is performed at the position where the laser light interferes. The selective reflection wavelength can be changed by changing the wavelength of the laser light used, or by adjusting the intersection angle of the two laser lights and the incident angle with respect to the substrate. In addition, if necessary, a light shielding film such as a photomask can be used.

As a liquid crystal material used for the liquid crystal optical element, a nematic liquid crystal material is particularly preferable. As the nematic liquid crystal material, any liquid crystal material such as a cyano-based, fluorine-based, and chlorine-based liquid crystal can be used. However, in order to perform active driving with an active element such as a thin film transistor (TFT), a fluorine-based material having a high charge retention rate is required. Liquid crystal materials are preferred. It is preferable that the dielectric anisotropy of the liquid crystal material is positive, but it is also possible to use a two-frequency driving liquid crystal material having both positive and negative values depending on the applied frequency, or a liquid crystal material having a negative dielectric anisotropy. it can.

The ratio of the liquid crystal material in the light control layer is 20% by weight.
The content is desirably at least 80% by weight and more desirably at least 30% by weight and at most 50% by weight. When the ratio of the liquid crystal material is larger than this range, it is difficult to form a laminated structure composed of the liquid crystal material and the transparent resin having different refractive indexes, and the light intensity of the selective reflection becomes weak. When the number is small, the driving voltage of the liquid crystal optical element becomes high.

In the present invention, indium tin oxide (ITO), a conductive polymer material, or the like can be used as a material for the electrode layer. The electrode layer is desirably transparent. The electrodes that apply a voltage to each electrode layer are:
It is not necessary to be transparent, and any conductive material such as a metal material and a conductive polymer material may be used as the electrode. When each light control layer is driven by an active element such as a thin film transistor, one electrode layer may be connected to the counter electrode, and the remaining electrode layers may be connected to each active element. Further, in order to increase the mechanical strength of the electrode layer, an electrode layer formed on a transparent substrate such as glass or plastic can be used. Further, a light absorbing layer can be provided on the electrode layer as needed.

In the present invention, it is preferred that at least one electrode layer is provided with a light absorbing layer. In this case, the light absorption layer is not particularly limited as long as it is a material that absorbs a visible light wavelength band, and various inorganic materials and organic materials can be used. The light absorption intensity or absorption wavelength can be arbitrarily changed according to the target device characteristics. The light absorbing layer may be formed on the light control layer side of the electrode layer, or may be formed between the electrode layer and the transparent substrate or on the transparent substrate opposite to the light control layer side. When it is formed on the opposite side of the light control layer, it may be attached on a transparent substrate after the light control layer is formed.

The light absorbing layer may be formed by coding a material absorbing the visible wavelength band on a transparent substrate such as glass or plastic, or may be formed by laminating a light absorbing substrate on a transparent substrate. In this case, the material that absorbs the visible light wavelength band may be on the dimming layer side or outside the transparent substrate. When the material that absorbs the visible light wavelength band is installed outside the transparent substrate,
After forming the dimming layer, a material that absorbs the visible light wavelength band may be laminated on the transparent substrate.

Japanese Patent Application Laid-Open No. 8-304848 discloses that a liquid crystal optical element in which liquid crystal optical elements that reflect light of red, green, and blue wavelengths are laminated has a reflection of light in a wavelength band mainly around 500 nm. A liquid crystal optical element is described in which display elements having a high efficiency are stacked on the light incident side. This element is similar to the present invention in that three display elements that reflect each of the three primary colors of light are stacked, but only the stacking order of display elements that reflect blue light is described. There is no description about the volume of the pixel portion of the light control layer described above.

[0032]

The present invention will be described in more detail with reference to the drawings. FIG. 1 is a perspective view schematically showing a basic configuration of a liquid crystal optical element according to an embodiment of the present invention. The liquid crystal optical element has a structure in which dimming layers 11 that respectively reflect the three primary colors of light, blue light, red light, and green light, are sandwiched between transparent substrates 13 with transparent electrode layers 12 and stacked.
By controlling the reflected light of each color, multi-coloring is achieved. The light absorbing layer 14 is provided on the outer surface of the lowermost transparent substrate 13.

FIG. 2 shows a case where the three light control layers in FIG. 1 are respectively a blue light reflection light control layer 22, a red light reflection light control layer 23, and a green light reflection light control layer 24 from above. It is sectional drawing of the liquid crystal optical element of. In this liquid crystal optical element, three light modulating layers 22 sandwiched between a transparent substrate 13 and an electrode layer 12,
The area and layer thickness of the pixel portion in 23 and 24 are set for each light control layer. Thereby, the driving voltage of each light control layer 11 can be controlled without breaking the color balance. Further, since the light reflection intensity of each color reflected by each of the light control layers 22, 23, and 24 is controlled, a display with good color balance can be obtained.

[0034]

Embodiments of the present invention will be described below. FIG.
Is a cross-sectional view showing a procedure for forming a liquid crystal display element used in the present liquid crystal optical element, and FIGS. 4 and 5 are cross-sectional views each showing a structure of the liquid crystal display element.

Example 1 A homogeneous mixture containing 65% by weight of Luxtrack LCR208 (manufactured by Toagosei Chemical Co., Ltd.) as the precursor compound 16 of the transparent resin and 35% by weight of PN001 (manufactured by RODIC) as the liquid crystal material 15 Make 21. As shown in FIG. 3, the transparent substrate 1 with two electrode layers 12 having a pixel area of 1 cm ² and a substrate interval of 7 μm was mixed with the uniform mixed solution 21 as shown in FIG.
3 to form a light control layer. Next, an argon laser beam 20 having a wavelength of 488 nm, which has been converted into two light beams by a beam splitter, interferes at a position of the uniform mixed solution 21.
The light was incident on the transparent substrate 13 from above and below. afterwards,
The polymerization reaction is terminated by irradiation with a high-pressure mercury lamp, and the liquid crystal material
Were periodically arranged to obtain a liquid crystal display element.

In the liquid crystal display device, as shown in FIG. 4, when light 17 was incident on the transparent substrate 13 in a state where no voltage was applied, light having a wavelength of about 520 nm was selectively reflected. In the figure, reference numeral 18 denotes reflected light, and 19 denotes transmitted light. As shown in FIG. 5, when an AC rectangular wave of 100 V and 30 V was applied to the liquid crystal display element, the wavelength was 520 nm.
The reflectance of nearby light has decreased.

A transparent substrate 13 with two electrode layers 12 having a pixel area of 1.2 cm ² and a substrate spacing of 7 μm,
And a pixel area of 0.9 cm ² with a substrate spacing of 7 μm.
Two liquid crystal display elements were produced by the same procedure as above except that the uniform mixed solution 21 was sandwiched between the two transparent substrates 13 with the electrode layers 12 and the incident angle of the laser beam 20 was changed. The liquid crystal display element having a pixel area of 1.2 cm ² selectively reflected light near the wavelength of 610 nm when no voltage was applied.
On the other hand, the liquid crystal display device having a pixel area of 0.9 cm ² selectively reflected light near the wavelength of 440 nm. When an AC rectangular wave of 28 V at 100 Hz was applied to a liquid crystal display element having a pixel area of 1.2 cm ² and an AC rectangular wave of 35 V at 100 Hz was applied to a liquid crystal display element having a pixel area of 0.9 cm ² , The reflectivity of light selectively reflected by the liquid crystal display element was reduced.

These 520 nm, 610 nm and 440 nm
Each liquid crystal display element that selectively reflects light in the vicinity of nm was laminated so that the pixel portions overlap each other, and the light absorbing layer 14 was attached to the lowermost part to obtain a target liquid crystal optical element. The obtained liquid crystal optical element showed white when no voltage was applied, and a multicolor display was obtained by applying a voltage to each light control layer.

COMPARATIVE EXAMPLE 1 The area of each pixel portion and the thickness of the light control layer were the same, and
Three liquid crystal display elements that selectively reflect light near 20 nm, 610 nm, and 440 nm were laminated, and the other conditions were treated in the same manner as in Example 1 to produce a liquid crystal optical element. In this case, the obtained liquid crystal optical element was slightly green when no voltage was applied.

Example 2 A uniform mixed solution containing 62% by weight of Luxtrack LCR208 (manufactured by Toagosei Chemical) as precursor compound 16 of a transparent resin and 38% by weight of PN001 (manufactured by RODIC) as liquid crystal material 15 21 is a transparent substrate 13 with two electrode layers 12 (each pixel area is 1 cm ² ,
μm). Argon laser light 20 (wavelength: 488 nm) converted into two light beams by the beam splitter was incident on the transparent substrate 13 from above and below so as to interfere with each other at the position of the uniform mixture 21. Thereafter, irradiation with a high-pressure mercury lamp was performed to terminate the polymerization reaction, thereby obtaining a liquid crystal display device in which the liquid crystal material 15 in the form of droplets was periodically arranged in the transparent resin 16 of the uniform mixed liquid 21. This liquid crystal display element selectively reflected light near the wavelength of 540 nm when no voltage was applied. As shown in FIG. 5, this liquid crystal display device
When an AC rectangular wave of 8 V was applied, the reflectance of light near a wavelength of 540 nm decreased.

A pixel area 1 having a substrate spacing of 7 μm was used.
two electrode layers 12 with the transparent substrate 13 of cm ^2, and a homogeneous mixed solution 21 was respectively sandwiched by two electrode layers 12 with the transparent substrate 13 of the pixel area 1 cm ² which was 8μm substrate gap, the laser beam Two liquid crystal display elements were produced in the same procedure as above except that the incident angle was changed to 20. A liquid crystal display element having a substrate spacing of 7 μm has a 450 n
Light near the m wavelength was selectively reflected. On the other hand, the liquid crystal display element having the substrate spacing of 8 μm selectively reflected light near the wavelength of 610 μm. For a liquid crystal display device with a substrate spacing of 7 μm,
When an AC rectangular wave of 33 V was applied at 100 Hz and an AC rectangular wave of 35 V at 100 Hz was applied to a liquid crystal display device having a substrate spacing of 8 μm, the reflectance of light selectively reflected by each liquid crystal display device was increased. Diminished.

These 540 nm, 610 nm and 450
Each liquid crystal display element that selectively reflects light in the vicinity of nm was laminated so that the pixel portions overlapped, and the light absorbing layer 14 was attached to the lowermost part to obtain a target liquid crystal optical element. The obtained liquid crystal optical element was white when no voltage was applied, and a multicolor display was obtained by applying a voltage to each dimming layer.

Comparative Example 2 The area of each pixel portion and the thickness of the light control layer were the same, and
Three liquid crystal display elements that selectively reflect light near 40 nm, 610 nm, and 450 nm were stacked, and the other conditions were treated in the same manner as in Example 2 to produce a liquid crystal optical element. In this case, the obtained liquid crystal optical element was slightly bluish green when no voltage was applied.

Example 3 The area of the pixel portion was 1.2 cm ² and the substrate interval was 5.5 μm.
m, a liquid crystal display element that reflects light around 530 nm, the pixel area is 1.3 cm ^2, and the substrate spacing is 6 μm.
A liquid crystal display element that reflects light near 620 nm, a pixel area of 1.2 cm ^2, and a substrate spacing of 5 μm,
Liquid crystal display devices that reflect light in the vicinity of nm were manufactured according to the procedure of Example 1. In each of the obtained liquid crystal display devices, the reflectivity of light was reduced by an AC rectangular wave of 20 V at 100 Hz.

These 530 nm, 620 nm and 460 nm
Each liquid crystal display element that selectively reflects light in the vicinity of nm was laminated so that the pixel portions overlapped, and the light absorbing layer 14 was attached to the lowermost part to obtain a target liquid crystal optical element. The obtained liquid crystal optical element was white when no voltage was applied, and a multicolor display was obtained by applying a voltage to each dimming layer.

Example 4 90 parts by weight of dipentaerythritol hexaacrylate, 4.95 parts by weight of benzuanthracene as a polymerization initiator, and 4.95 parts by weight of isoamyl 4-dimethylaminobenzoate as a polymerization initiator A transparent resin precursor comprising a mixture of 0.1 parts by weight of acridine orange base as a dye sensitizer, and TL-21 as a liquid crystal material
5 (manufactured by Merck), and the same operation as in Example 1 was carried out to produce a liquid crystal display device.

An AC rectangular wave of 31 V at 100 Hz was applied to a liquid crystal display element having a pixel area of 1.2 cm ^{2, and} a pixel area of 0.1 V was used.
For a 9 cm ² liquid crystal display element, an AC rectangle of 36 V at 100 Hz is used, and for a liquid crystal display element having a pixel area of 1.0 cm ² , 1 is used.
A 31 V AC rectangle was applied at 00 Hz. At this time, the reflectance of light selectively reflected by each liquid crystal display element decreased.

These 520 nm, 610 nm and 440 nm
A liquid crystal display element that selectively reflects light in the vicinity of nm is laminated so that the pixel portions overlap each other, and the light absorbing layer 14 is attached to the lowermost part to obtain a target liquid crystal optical element. The obtained liquid crystal optical element was white when no voltage was applied, and a multicolor display was obtained by applying a voltage to each dimming layer.

Example 5 90 parts by weight of dipentaerythritol pentaacrylate and 4.95 of phenanthrenequinone as a polymerization initiator
A transparent resin precursor comprising a mixture of 4.95 parts by weight of 4,4-diethylaminobenzophenone as a polymerization initiator and 0.1 part by weight of rose bengal as a dye sensitizer; and a liquid crystal material. TN-403 (RO
The same operation as in Example 2 was performed except that DIC (manufactured by DIC Corporation) was used. Thereby, when no voltage is applied, 540 n
A liquid crystal display element which selectively reflects light near the wavelengths of m, 450 nm and 610 nm was manufactured.

These 540 nm, 450 nm and 610 nm
A liquid crystal display element that selectively reflects light in the vicinity of nm is laminated so that the pixel portions overlap each other, and the light absorbing layer 14 is attached to the lowermost part to obtain a target liquid crystal optical element. The obtained liquid crystal optical element was white when no voltage was applied, and a multicolor display was obtained by applying a voltage to each dimming layer.

FIG. 6 is a graph showing the correlation between the wavelength of the incident light of the liquid crystal optical element according to the present embodiment and the reflected light of each color. From this graph, in the present liquid crystal optical element in which the light control layers 22, 23, and 24 and the electrode layers 12 are alternately laminated, the light reflection intensity of the color reflected by each light control layer is well controlled,
It can be seen that the reflectances of blue, red and green are almost the same, and that the color balance is extremely good.

As described above, in the present liquid crystal optical element, only the driving voltage of each light control layer is arbitrarily controlled while maintaining the color tone and light reflection intensity of each light control layer, so that the liquid balance is maintained without disturbing the color balance. The drive waveform of the optical element can be simplified.

Although the present invention has been described based on the preferred embodiments (examples), the liquid crystal optical element of the present invention is not limited to the above embodiments (examples). Liquid crystal optical elements obtained by making various modifications and changes from the above embodiment are also included in the scope of the present invention.

[0054]

As described above, according to the present invention,
It is possible to obtain a liquid crystal optical element having a wide color range of display colors and a good color balance, and in particular, a white color which is displayed when no voltage is applied and is not colored.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a basic configuration of a liquid crystal optical element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a liquid crystal optical element in a case where the dimming layers in FIG. 1 are respectively formed from above, as blue light, red light, and green light.

FIG. 3 is a cross-sectional view for explaining a procedure for forming a liquid crystal display element used in the present liquid crystal optical element.

FIG. 4 is a cross-sectional view showing a structure of a liquid crystal display element used in the present liquid crystal optical element.

FIG. 5 is a cross-sectional view illustrating a structure of a liquid crystal display element used in the present liquid crystal optical element.

FIG. 6 is a graph showing the correlation between the wavelength of incident light of the present liquid crystal optical element and the reflected light of each color.

FIG. 7 is a cross-sectional view schematically showing a liquid crystal optical element of a conventional liquid crystal display device.

FIG. 8 is a graph showing the correlation between the wavelength of incident light and the reflected light of each color in a conventional liquid crystal optical element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Dimming layer 12 Electrode layer 13 Transparent substrate 14 Light absorption layer 15 Liquid crystal material 16 Transparent resin 17 Incident light 18 Reflected light 19 Transmitted light 20 Laser light 21 Uniform mixed liquid 22 Dimming layer for blue 23 Dimming for red Layer 24 Dimming layer for green

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-304848 (JP, A) JP-A-6-294952 (JP, A) JP-A-7-181483 (JP, A) JP-A-63-181 228129 (JP, A) JP-A-64-50919 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1347 G02F 1/1334

Claims (10)

(57) [Claims] 1. A reflection type liquid crystal optical element, comprising: a plurality of liquid crystal display elements each having a light control layer in which a liquid crystal material is layered and regularly arranged in a transparent resin sandwiched between electrode layers; Each of the light control layers reflects a specific wavelength band in the visible light region,
The volumes of the pixel portions are different from each other, and at least one of the layer thickness of the effective display portion in each of the light control layers and the area on the viewing surface side of the pixel portion in each of the light control layers is different for each liquid crystal display element. A liquid crystal optical element characterized by being different. 2. The liquid crystal optical element according to claim 1, wherein the light reflected by each of the light control layers of the plurality of liquid crystal display elements is red, green, and blue, respectively. 3. The area on the viewing surface side of the pixel portion in the light control layer that reflects red light is at least 0.5 times and twice the area on the viewing surface side of the pixel portion in the light control layer that reflects blue light. 3. The liquid crystal optical element according to claim 2, wherein: 4. An area on the viewing surface side of a pixel portion in a light control layer that reflects green light is 0.5 times or more and 2 times or less the thickness of the light control layer that reflects blue light. The liquid crystal optical element according to claim 2. 5. The light control layer that reflects red light has a layer thickness of 0.5 times or more and 2 times or less the thickness of the light control layer that reflects blue light. Any one of 4
Item 10. The liquid crystal optical element according to item 9. 6. The light control layer that reflects green light has a layer thickness of 0.5 times or more and 1.5 times or less the thickness of the light control layer that reflects blue light. 6. The liquid crystal optical element according to any one of 1 to 5. 7. The liquid crystal optical element according to claim 1, wherein the plurality of liquid crystal display elements are connected to corresponding active elements, respectively. 8. The ordinary light refractive index of the liquid crystal material matches the refractive index of the transparent resin, and the dimming layer enters a light reflecting state when no voltage is applied, and the intensity of reflected light increases as the applied voltage increases. The liquid crystal optical element according to claim 1, wherein the liquid crystal optical element decreases. 9. The liquid crystal optical element according to claim 1, wherein the electrode layer is made of a conductive polymer material. 10. The liquid crystal optical element according to claim 1, wherein a light absorbing layer is provided on at least one electrode layer.