JP2828062B2 - Liquid crystal optical element and manufacturing method thereof - 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 in a display device for displaying characters, figures, and the like, which is selectively reflected when no voltage is applied and is in an absorbing state when voltage is applied, and a method of manufacturing the same. Things.

[0002]

2. Description of the Related Art In recent years, with the spread of electronic organizers, mobile phones, and the like, further improvement in the operation time of mobile terminals has come to the fore. One solution for improving the operation time of a portable terminal using a liquid crystal display is to use a device that does not require a backlight as a liquid crystal device, that is, a reflective liquid crystal device. As for the reflection type, a GH (guest-host) mode, an electric field controlled birefringence (ECB) mode, a TN mode, and a holographic polymer dispersed liquid crystal (HPDLC) have been reported.

On the other hand, in the method disclosed in International Application No. 92/19695, in which a trace amount of a polymer compound is dispersed in a chiral nematic liquid crystal, the liquid crystal phase forms a planar texture under no electric field application and selectively reflects visible light. State taking,
There has been obtained a liquid crystal optical element which forms a focal conic texture under voltage application and becomes translucent. This selective reflection wavelength λ is represented by λ = n · P. n is the average refractive index of the liquid crystal molecules, and P is the helical pitch of the chiral nematic liquid crystal.

This liquid crystal optical element, which is generally called a polymer-stabilized cholesteric texture (PSCT) element, is capable of selectively reflecting / reflecting a phase change of a chiral nematic liquid crystal.
Utilizing the property of semi-transmission, a reflective liquid crystal optical element capable of taking a selective reflection state and a light absorption state can be manufactured by combining with a light absorption layer. Further, since the reflection type liquid crystal optical element has bistability, it can be driven by a simple matrix.

[0005] In the above-mentioned International Application No. 92/19695, the selective reflection wavelength of the chiral nematic liquid crystal is the same in the liquid crystal panel plane, and a monochrome display is exemplified.
Multi-color display is indispensable for use as an information display, but it is difficult to realize multi-color display using the disclosed technology.

SID '95 DIGEST, p169
(1995) proposes a method of changing the helical pitch by extinguishing the chirality of the chiral agent by light. According to this method, since the helical pitch of a portion irradiated with light is reduced, it is possible to achieve multi-color by changing the light irradiation condition on the display unit.

[0007]

SUMMARY OF THE INVENTION However, SID
In the technique disclosed in '95 DIGEST, p169 (1995), first, it is necessary to synthesize a chiral agent having a property of losing optical activity by light irradiation. As a method for obtaining a chiral agent that is an optically active substance, generally, a method of synthesizing a racemic body, then performing optical resolution by column chromatography or the like, asymmetric synthesis using an asymmetric catalyst, or the like is known. is there. But,
In any of these processes, means for separating and purifying the optically active substance is required.

As described above, the reflection type liquid crystal optical element corresponding to multi-color is expected as a variety of information display elements. However, the existing technology cannot provide a device having a large contrast and a bright contrast and a simple manufacturing method thereof. Had not been.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a liquid crystal having no optical activity, that is, an achiral photosensitive compound having a chiral nematic liquid crystal is used. The present inventors have found that asymmetric induction by a photoreaction in a liquid crystal of an optical element changes the helical pitch of a chiral nematic liquid crystal, thereby obtaining a multicolor liquid crystal optical element having different selective reflection wavelengths for each domain. completed.

That is, the present invention provides a light control layer comprising a chiral nematic liquid crystal, a polymer compound and an achiral photosensitive compound sandwiched between two substrates having at least one transparent and at least one electrode. It is.

Conventionally, it has been reported that asymmetric induction of prechiral compounds by reduction, addition, etc. in an asymmetric environment in which an asymmetric catalyst or ligand (ligand) is present has been reported by Otsuka,
It is known in the literature such as "Progress of Asymmetric Synthesis and Optical Resolution" edited by Kazuki Mukaiyama (Chemical Doujin). However, the present invention has an effect that, by using this asymmetric induction as a light control layer of a liquid crystal display device, it is possible to realize a multi-color chiral nematic liquid crystal optical device for the first time by an easy method.

The present invention is a liquid crystal optical element characterized in that the light modulating layer is an aggregate of fine domains of chiral nematic liquid crystal having at least two kinds of helical pitches. More specifically, at least one is transparent. An chiral photosensitive compound in which an asymmetric carbon is generated by a photoreaction between two substrates having electrodes on at least one of the substrates;
That is, the liquid crystal optical element is characterized in that a prechiral compound undergoes a photoreaction in a chiral nematic liquid crystal, thereby changing the generation ratio of each enantiomer and changing the helical pitch of the chiral nematic liquid crystal.
ADVANTAGE OF THE INVENTION According to this invention, multicoloring can be easily implement | achieved, without using the special optically active compound which has the characteristic of losing optical activity by a photoreaction.

Further, the present invention relates to a method for producing a liquid crystal optical element, characterized in that the achiral photosensitive compound is asymmetrically induced by light irradiation to change the helical pitch of the chiral nematic liquid crystal. Is transparent and has an electrode on at least one side.
An achiral photosensitive compound in which asymmetric carbon is generated by a photoreaction between two substrates, that is, a prechiral compound,
This is a method for producing a liquid crystal optical element, characterized in that a photoreaction in a chiral nematic liquid crystal changes the formation ratio of each enantiomer, and the helical pitch of the chiral nematic liquid crystal changes.

According to the present invention, multicoloring can be easily realized without using an optically active compound having the property of losing optical activity by a photoreaction.

In the method of manufacturing a liquid crystal optical element according to the present invention, light irradiation may be performed while a voltage is applied between the electrodes. By changing the phase of the chiral nematic liquid crystal by applying a voltage, the degree of asymmetric induction of the achiral photosensitive compound differs even under the same light irradiation conditions, and a multi-color liquid crystal optical element can be manufactured. According to this method, the number of light irradiations is reduced, and a photomask for producing domains having different selective reflection wavelengths is not required.

As the material of the substrate used in the present invention, glass, plastic, metal and the like can be used. The substrate is set so that the electrode layer is on the light control layer side. Note that at least one of the substrates used in the present invention may be transparent, but it is preferable that one of the reflective liquid crystal elements is transparent and the other is a light absorbing plate. The light absorbing plate may be an inorganic material or an organic material as long as it is made of a material that absorbs visible light. The absorption intensity or absorption wavelength can be arbitrarily changed depending on the target device characteristics. The structure may be such that the light absorbing material forms the entire light absorbing plate,
The light absorbing material may be coated on a substrate made of another material such as glass. When coated with a light absorbing material, the light absorbing material need not be on the light modulating layer side. Further, the substrate on which the light absorbing material is coated is not necessarily required to be transparent when the light absorbing material is not located on the light control layer side. When the light absorbing material has conductivity, it can be used also as an electrode.

The electrode layer used in the present invention can be provided on two substrates so as to face each other, or the electrodes can be provided on one substrate as in in-plane switching. . As the material for the electrode layer, a material such as ITO can be used. However, if the substrate used has conductivity, the substrate can also be used as an electrode.

These substrates with electrode layers may be untreated so that the liquid crystal is oriented, but are desirably treated. At this time, the two substrates may be in a homogeneous orientation, or one may be in a homogeneous orientation,
A so-called hybrid in which the other is homeotropic alignment may be used. These alignment treatments include:
Ordinary alignment films such as polyimide used for TN liquid crystal, STN liquid crystal and the like can be used. It is desirable to perform a rubbing process.

For setting the distance between the substrates, a rod shape made of glass, polymer, or the like used in a normal liquid crystal device,
Spherical spacers can be used with a spacing of 2
It is desirable that the thickness be in the range of about μm to 20 μm.

As the liquid crystal used in the liquid crystal optical element of the present invention, a chiral nematic liquid crystal obtained by mixing a chiral agent in a nematic liquid crystal is used, and a normal cholesteric liquid crystal having similar characteristics to this is also used. Can be used.

As the nematic liquid crystal, any liquid crystal such as cyano-based, fluorine-based, and chlorine-based can be used. The mixing ratio between the nematic liquid crystal and the chiral agent is determined by the desired selective reflection wavelength. The selective reflection wavelength λ of the chiral nematic liquid crystal is represented by the product of the helical pitch P of the liquid crystal and the average refractive index n of the liquid crystal. When used as a selective reflection type, it is desirable to satisfy the condition of 0.38 μm <P · n ≦ 0.8 μm.

The liquid crystal optical element of the present invention can be manufactured by sandwiching a mixture of a chiral nematic liquid crystal and a polymer precursor between substrates having a fixed gap, and then irradiating light. At this time, the mixture may be injected under reduced pressure or normal pressure. If necessary, heating may be performed.

As the chiral agent, a usual optically active compound can be used. For example, chiral agent S81 manufactured by Merck
1, R811, S1011, R1011 and the like. The optically active compound may be an R-form or an S-form, or two or more compounds may be mixed.

Although it is not always necessary to add a polymer compound to the liquid crystal optical element of the present invention, it is preferable to add a polymer compound to stabilize a planar texture exhibiting a selective reflection state. The polymer compound to be added may be a homopolymer obtained by polymerizing one kind of polymer precursor (monomer) or a copolymer obtained by copolymerizing two or more kinds of polymer precursors. This polymer precursor can be selected from thermosetting or photocurable polymer precursors, but the photocurable polymer precursor should be used because of the ease and uniformity of liquid crystal optical element fabrication. Is desirable.

As the thermosetting polymer precursor, an epoxy compound or the like can be used. As the photocurable polymer precursor, any polymer precursor having a usual photopolymerizable group such as an acryloyl group or a vinyl group can be used. A plurality of photopolymerizable groups may be present in one molecule of the polymer precursor. For example, 2-ethylhexyl acrylate, butylethyl acrylate, butoxyethyl acrylate, 2
-Cyanoethyl acrylate, benzyl acrylate,
Cyclohexyl acrylate, 2-hydroxypropyl acrylate, 2-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,
Monofunctional acrylate compounds such as phenoxyethyl acrylate and phenoxydiethylene glycol acrylate, 2-ethylhexyl methacrylate, butylethyl methacrylate, butoxyethyl methacrylate, 2-
Cyanoethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 2-hydroxypropyl methacrylate, 2-ethoxyethyl acrylate, 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, phenoxydiethylene glycol methacrylate, etc. Monofunctional methacrylate compound, 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 Polyfunctional acrylate compounds such as acrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, urethane acrylate oligomer, diethylene glycol di Methacrylate, 1,4
-Butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, dicyclopentanyl dimethacrylate glycerol dimethacrylate, 1,6-
Hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate,
Examples include, but are not limited to, polyfunctional methacrylate compounds such as pentaerythritol trimethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol monohydroxypentamethacrylate, and urethane methacrylate oligomer.

The polymer compound is desirably contained in the chiral nematic liquid crystal in an amount of 0.1% by weight or more and 20.0% by weight or less. In particular, if it is too large, the reflectance of visible light when no voltage is applied is reduced, and the driving voltage becomes extremely high.

As the light beam used for photopolymerization of the precursor of the polymer compound, an electron beam can be used in addition to visible light and ultraviolet light. When performing photopolymerization using visible light or ultraviolet light, it is desirable to add a photopolymerization initiator to promote the reaction. Examples of the photopolymerization initiator include 2,2-diethoxyacetophenone and 2-hydroxy-2-methyl-1-.
Phenyl-1-one, 1- (4-isopropylphenyl-)-2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-
Acetophenones such as 2-methylpropan-1-one,
Benzoin based compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl dimethyl ketal, benzophenone, benzoyl benzoic acid, 4-phenylbenzophenone, 3,3-
Benzophenones such as dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone,
Thioxanthone, such as 2-methylthioxanthone, diazonium salt, sulfonium salt, iodonium salt,
Conventional photopolymerization initiators such as selenium salts can be used.
The initiator may be a solid or a liquid, but it is desirable that the initiator be dissolved or compatible with the liquid crystal in view of the uniformity of the device. The initiator concentration is preferably 30% by weight or less of the polymer precursor. If necessary, a photoinitiating auxiliary such as methyldiethanolamine and 4-dimethylaminobenzoic acid can be added.

Among the chiral nematic liquid crystals, the chiral nematic liquid crystal has a different ratio of each enantiomer among the chiral nematic liquid crystals.
That is, any compound can be used as long as it is a compound that induces asymmetry. For example, there are aniline-based compounds as shown in the following (1) to (8), but the invention is not limited thereto.

A chiral nematic liquid crystal, which is an asymmetric environment for realizing asymmetric induction by a photoreaction, can be added with a small amount of an asymmetric catalyst to improve the optical purity of the asymmetric induction.

As the light used for the photoreaction of the achiral photosensitive compound, visible light, ultraviolet light and electron beam can be used.

[0031]

Embedded image

In the present invention, “asymmetric induction” means that the optical purity is larger than 0. The optical purity is a value representing the excess of a pair of enantiomers as a percentage. That is, an optical purity of 0 indicates a racemic form, and if only one of the enantiomers is used, the optical purity is 100.

The fine domain of the present invention indicates a general display pixel, and the shape of the pixel may be a rectangle, a square, a hexagon, or the like. Each domain may be separated by a wall of a polymer or the like.

The liquid crystal optical element of the present invention can be used not only in a single layer but also in a laminated state. At this time, only the light control layer may be laminated, or a layer formed on the substrate may be laminated. Chiral nematic liquid crystal with the same helical pitch but different only in the helical direction, that is, the same selective reflection wavelength, the chiral nematic liquid crystal of one liquid crystal optical element has a right spiral,
When the chiral nematic liquid crystal of the other liquid crystal optical element is a left spiral, it can reflect left and right circularly polarized light,
Light reflection efficiency is improved.

The liquid crystal optical element of the present invention can be manufactured by irradiating different light to different domains. In this manufacturing method, a light shielding film such as a photomask can be used to irradiate different light to different domains, or light can be optically narrowed down to each domain size.

Further, the present invention relates to a method for producing a liquid crystal optical element, in which light is irradiated while an electric field is applied between the electrodes. According to this method, the phase of the chiral nematic liquid crystal is changed by applying a voltage. By doing so, the degree of asymmetric induction of the achiral photosensitive compound differs under the same light irradiation conditions, and a multi-color liquid crystal optical element can be manufactured. The frequency, waveform, and voltage of the electric field used in this manufacturing method can be arbitrarily selected depending on the liquid crystal material used and the desired degree of asymmetric induction. Note that it is not always necessary to irradiate the same light between domains having different applied voltages. Further, a magnetic field may be applied instead of the electric field.

Applications of the liquid crystal optical element of the present invention include a building material such as a window and a partition, and a display device for displaying characters and figures.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

[0039]

【Example】

Example 1 A nematic liquid crystal E8 (manufactured by Merck) and a chiral agent S1011 (manufactured by Merck) were mixed to prepare a chiral nematic liquid crystal having a selective reflection wavelength of about 750 nm. The chiral nematic liquid crystal and the achiral photosensitive material N-
A mixed solution of methyl-N-isopropenylaniline, an ultraviolet-curable monomer 4,4'-bisacryloyloxy-α, α'-diethylstilbene and a polymerization initiator benzoin methyl ether was injected into a liquid crystal cell which had been subjected to antiparallel horizontal alignment treatment. . One substrate of this liquid crystal cell was a light absorbing plate.

The liquid crystal cell was irradiated with 365-nm ultraviolet rays from the transparent substrate side to cure the ultraviolet-curing monomer. Further, the liquid crystal cell was divided into two parts by a photomask, and one was irradiated with ultraviolet light. As a result, the selective reflection wavelength was shorter than that of the masked part. As a result, two colors of selective reflection were obtained in one liquid crystal cell. As a result of applying a pulse voltage to the fabricated element, both of the elements transited from the selective reflection state (planar texture) to the focal conic texture, and this state was stored. In the focal conic texture, the selective reflection disappeared and the display became black. Next, as a result of applying another pulse voltage, it returned to the selective reflection state.

(Example 2) A nematic liquid crystal E8 (manufactured by Merck) and a chiral agent S1011 (manufactured by Merck) were mixed to prepare a chiral nematic liquid crystal having a selective reflection wavelength of about 750 nm. This chiral nematic liquid crystal and an achiral photosensitive material N-methyl-N-isopropenylaniline,
A mixed solution of an ultraviolet curable monomer 4,4'-bisacryloyloxy-α, α'-diethylstilbene and a polymerization initiator benzoin methyl ether was injected into a liquid crystal cell which had been subjected to antiparallel horizontal alignment treatment. One substrate of this liquid crystal cell was a light absorbing plate. The liquid crystal cell was divided into two parts by a photomask, and one of the ^two was irradiated with 0.1 mW / cm ² ultraviolet rays (wavelength 365 nm) and the other was irradiated with 50 mW / cm ² ultraviolet rays from the transparent substrate side. Polymerization and asymmetric induction were performed simultaneously. As a result, the selective reflection wavelength of the element irradiated with strong ultraviolet rays became short, and two colors of selective reflection were obtained in one liquid crystal cell. As a result of applying a pulse voltage to the fabricated element, both of the elements transited from the selective reflection state (planar texture) to the focal conic texture, and this state was stored. In the focal conic texture, the selective reflection disappeared and the display became black. Next, as a result of applying another pulse voltage,
It has returned to the selective reflection state.

(Embodiment 3) Nematic liquid crystal TL215
A chiral nematic liquid crystal having a selective reflection wavelength of about 550 nm obtained by mixing a chiral agent S811 (manufactured by Merck) and a chiral agent S811 (manufactured by Merck) was used, and an achiral photosensitive material N-methyl-N- was used.
Except for using (α-styryl aniline), all were produced under the same conditions as in Example 2.

Also in this liquid crystal cell, the selective reflection wavelength was short at the portion irradiated with strong ultraviolet rays.

(Example 4) Nematic liquid crystal TL215
(Merck) and a chiral agent S811 (Merck) were mixed to prepare a chiral nematic liquid crystal having a selective reflection wavelength of about 750 nm. A mixed solution of this chiral nematic liquid crystal, an achiral photosensitive material N-methyl-N- (α-styrylaniline), an ultraviolet curable monomer 4,4′-bisacryloyloxybiphenyl and a polymerization initiator benzoin methyl ether is horizontally aligned in an anti-parallel manner. It was injected into the treated liquid crystal cell. One substrate of this liquid crystal cell was a light absorbing plate. This liquid crystal cell is divided into three parts using a photomask,
To each ^{0.1mW / cm 2, 2mW / cm} 2, 40mW
/ Cm ² was applied from the transparent substrate side. As a result, selective reflection of three colors of red, green and blue was obtained in one liquid crystal cell. As a result of applying a pulse voltage to the fabricated device, both devices were selectively reflected (planar texture)
And transferred to the focal conic texture and memorized this state. In the focal conic texture, the selective reflection disappeared and the display became black. Next, as a result of applying another pulse voltage, it returned to the selective reflection state.

Example 5 An element was manufactured in the same manner as in Example 4 except that a polymer wall was formed between each divided pixel. The polymer wall was prepared by adding a photocurable monomer material, which is a raw material of the wall, to a liquid crystal solution, and irradiating light to the wall portion. This polymer wall was prepared before the process of developing the asymmetry induction. As a result, selective reflection of three colors of red, green, and blue was obtained as in Example 4. In this device, the pressure resistance was improved by the contribution of the polymer wall, and at the same time, the diffusion of the liquid crystal was suppressed.

Example 6 A nematic liquid crystal E8 (manufactured by Merck) and a chiral agent S1011 (manufactured by Merck) were mixed to prepare a chiral nematic liquid crystal having a selective reflection wavelength of about 750 nm. This chiral nematic liquid crystal and an achiral photosensitive material N-methyl-N-isopropenylaniline,
A mixed solution of an ultraviolet curable monomer 4,4'-bisacryloyloxy-α, α'-diethylstilbene and a polymerization initiator benzoin methyl ether was injected into a liquid crystal cell which had been subjected to antiparallel horizontal alignment treatment. One substrate of this liquid crystal cell was a light absorbing plate. Ultraviolet rays were irradiated from the transparent substrate side to cure the ultraviolet curable monomer. Next, half of the cell was uniformly irradiated with ultraviolet rays while no voltage was applied, and the other half was applied with an electric field. After the ultraviolet irradiation, the entire cell was set to a state where no voltage was applied. As a result, the selective reflection wavelength of the portion where no voltage was applied was shorter than the selective reflection wavelength of the portion where the voltage was applied. As a result of applying a pulse voltage to the fabricated element, both of the elements transited from the selective reflection state (planar texture) to the focal conic texture, and this state was stored. In the focal conic texture, the selective reflection disappeared and the display became black. Next, as a result of applying another pulse voltage, it returned to the selective reflection state.

(Example 7) An element manufactured by the same method as in Example 4 and an element manufactured by the same method as in Example 4 were laminated, except that R811 was used as a chiral agent. 2
Opposing pixels of one element have different helical pitches at the same helical pitch. One light absorbing plate was used on the outside. As a result, selective reflection of three colors of red, green and blue was obtained in one liquid crystal cell.

The intensity of the selectively reflected light was about twice that of a single layer. As a result of applying a pulse voltage to the fabricated element, both of the elements transited from the selective reflection state (planar texture) to the focal conic texture, and this state was stored. In the focal conic texture, the selective reflection disappeared and the display became black. next,
As a result of applying another pulse voltage, it returned to the selective reflection state.

[0049]

According to the liquid crystal optical element of the present invention, multicolor can be easily realized by a simple process of irradiating an achiral compound with light. Further, according to the method for manufacturing a liquid crystal optical element of the present invention, not only the light irradiation conditions are changed, but also under the same light irradiation conditions, due to the phase change of the chiral nematic liquid crystal by applying a voltage, the achiral photosensitive compound can be used. The degree of asymmetry is different, and a multi-color liquid crystal optical element can be manufactured. According to this manufacturing method, the number of times of light irradiation becomes one, and a photomask for manufacturing domains having different selective reflection wavelengths is not required.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic view of a liquid crystal optical element of the present invention.

FIG. 2 is a diagram illustrating an ultraviolet irradiation state and a selective reflection state of the liquid crystal optical element according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a selective reflection state of a liquid crystal optical element according to Example 5 of the present invention.

FIG. 4 is a view showing a liquid crystal optical element according to a sixth embodiment of the present invention in an ultraviolet irradiation state.

FIG. 5 is a diagram illustrating a selective reflection state of a liquid crystal optical element according to a sixth embodiment of the present invention.

FIG. 6 is a diagram illustrating a selective reflection state of a liquid crystal optical element according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Electrode layer 3 Alignment film 4 Polymer compound 5 Chiral nematic liquid crystal 5R Chiral nematic liquid crystal of right spiral 5L Chiral nematic liquid crystal of left spiral 6 Light absorption plate 7 Photomask 8 Polymer wall

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Goro Saito 5-7-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Yasuharu Onishi 5-7-1 Shiba, Minato-ku, Tokyo NEC Incorporated (58) Fields surveyed (Int.Cl. ⁶ , DB name) G02F 1/137 G02F 1/13

Claims (15)

(57) [Claims] An asymmetric carbon formed by at least a chiral nematic liquid crystal and light between two substrates having at least one transparent and at least one electrode.
A liquid crystal optical element having a light control layer containing an achiral photosensitive compound that exhibits asymmetric induction by a photoreaction in a chiral nematic liquid crystal. 2. The liquid crystal optical element according to claim 1, wherein the helical pitch of the chiral nematic liquid crystal is changed by asymmetric induction of the achiral photosensitive compound. 3. The liquid crystal optical element according to claim 1, wherein the light control layer contains a polymer compound. 4. A liquid crystal optical element according to claim 3, wherein said polymer compound is a compound obtained by photopolymerizing a polymer precursor. 5. The liquid crystal optical element according to claim 1, wherein said light modulating layer is an aggregate of at least two or more types of fine domains each composed of a chiral nematic liquid crystal having a different helical pitch. 6. The liquid crystal optical element according to claim 5, wherein a wall made of a polymer for isolating each domain is provided between the aggregate of the fine domains. 7. The liquid crystal optical element according to claim 1, wherein said substrate has an alignment film. 8. The liquid crystal optical element according to claim 1, wherein the chiral nematic liquid crystal takes a planar texture when no electric field is applied, and has a focal conic texture when an electric field is applied. 9. A reflective liquid crystal optical element according to claim 1, wherein one of said substrates has a light absorbing plate. 10. A composite liquid crystal optical element comprising at least two light control layers according to claim 1 laminated. 11. The light control device according to claim 10, wherein at least two light control layers having different selective reflection wavelengths are laminated.
The liquid crystal optical element according to the above. 12. A light control device comprising a chiral nematic liquid crystal, a polymer compound, and an achiral photosensitive compound which forms asymmetric carbon by light between two substrates having at least one of them transparent and having at least one electrode. A method for producing a liquid crystal optical element, comprising sandwiching a layer and irradiating the layer with light to induce asymmetric induction of the photosensitive compound to change the helical pitch of the chiral nematic liquid crystal. 13. A method for manufacturing a liquid crystal optical element according to claim 12, wherein light irradiation is performed in a state where a voltage is applied between electrodes at desired positions. 14. A different voltage is applied to at least two or more display units having electrodes.
The manufacturing method of the liquid crystal optical element of the description. 15. A method for manufacturing a liquid crystal optical element according to claim 14, wherein the same light irradiation is performed on at least two or more display sections having electrodes.