JP3036463B2 - 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 display device for displaying characters, figures, etc., a dimming device in which the amount of transmission of incident light changes,
The present invention relates to a liquid crystal optical element used for an optical shutter or the like. More specifically, the present invention relates to a liquid crystal optical element having a light control layer composed of a smectic liquid crystal material and a polymer resin.

[0002]

2. Description of the Related Art N.C. A. Clark, S.M. T. La
Gerwall proposes an optical element using the optical switching phenomenon of a ferroelectric liquid crystal material (App.
hys. Lett. , Vol. 36, p. 899 (19
80)). The surface-stabilized ferroelectric liquid crystal (SSFLC) optical element is characterized by a high optical response (1 millisecond or less) and a wide viewing angle. However, SSFLC is bistable, and the electro-optical response of the SSFLC optical element is limited to switching between two states, a bright state and a dark state. Therefore, there is a problem that it is difficult to display a halftone by controlling the voltage. In addition, the liquid crystal layer has a problem that the liquid crystal layer easily forms a chevron structure, thereby lowering the contrast, causing a layer structure to be easily disturbed by mechanical impact, and making it difficult to recover the orientation that has been disturbed once.

As another optical element, a liquid crystal material having an antiferroelectric phase (antiferroelectric liquid crystal material) has been reported by Chandani et al. (Jpn. J. Appl. Phy.).
s. , 28 (1989), L1265), and a display element using an antiferroelectric liquid crystal material has been proposed (J.
pn. J. Appl. Phys. , 29 (1990) 1
757). The antiferroelectric liquid crystal material has three stability based on the phase transition between the antiferroelectric phase and the ferroelectric phase, and by switching these under bias voltage application, optical control that can perform halftone display by voltage control. An element can be manufactured. However, there are problems such as the necessity of a bias voltage for halftone display and the complicated driving waveform of an optical element having high definition and many scanning lines.

On the other hand, drying and Tanaka et al. Have reported a smectic liquid crystal material in which the optical axis of a liquid crystal layer continuously changes with applied voltage (hereinafter referred to as a non-smectic smectic liquid crystal material). Proceedings of the 21st Liquid Crystal Symposium 2CO4, p.222 (1995), and p.25
0 (1995)). A threshold smectic liquid crystal optical element using this material has a feature that it does not have a definite threshold value for phase transition due to an applied voltage and has a small hysteresis characteristic. By combining this non-smectic liquid crystal optical element with an active matrix electrode such as a MIM or a thin-layer transistor (TFT), it is possible to obtain a display capable of halftone display and high-speed response.

Japanese Patent Application Laid-Open No. Hei 6-289372 describes a liquid crystal optical element having a dimming layer composed of a smectic liquid crystal material exhibiting antiferroelectricity and a polymer resin. This element belongs to a light scattering mode represented by a PDLC or NCAP element, and a polymer resin dispersed in the element plays a role of expressing a refractive index difference from a liquid crystal material. In this case, the ratio of the liquid crystal material to the resin in the light control layer is 4: 6 or 8: 2, that is, 25 to 150 parts by weight of the resin is used for 100 parts by weight of the liquid crystal material.

[0006] Proceedings of the 21st Liquid Crystal Symposium
18, p. 180 (1995) describes a liquid crystal optical element in which a polymer resin is formed and dispersed in a ferroelectric liquid crystal material. However, the liquid crystal material used in this device is a ferroelectric liquid crystal material having bistability, and the electro-optical response is limited to switching between two states, a bright state and a dark state. The polymer resin dispersed in the liquid crystal layer plays a role of obtaining a pseudo bookshelf structure of the liquid crystal layer. Accordingly, the liquid crystal optical element of the present invention is different from the liquid crystal optical element in the liquid crystal material, the electro-optical response of the liquid crystal material, and the role of the polymer resin.

[0007] As another report, 16th Intern
national Liquid Crystal Co
Nreference E2, 005 (1996) describes a liquid crystal optical element in which a polymer resin is dispersed in a ferroelectric liquid crystal material. However, in this device, the liquid crystal material is a ferroelectric liquid crystal material having bistability, and the polymer resin dispersed in the liquid crystal layer plays a role of preventing the substrate surface rotation phenomenon of the liquid crystal layer, This is different from the optical element of the present invention.

[0008]

In a non-smectic liquid crystal optical element, when a voltage-applied state is maintained for a long time, the value of the applied voltage at which the light transmittance is minimized deviates from 0 V (no voltage applied state). In addition, there is a problem in that the curves of the light transmittance with respect to the voltage on the step-up side and the voltage on the step-down side do not match, and further, when the state where no voltage is applied is maintained for a long time, the alignment of the liquid crystal is disturbed. These three problems appear on the display as phenomena of flickering and lowering of contrast, and significantly lower the quality of the displayed image. An object of the present invention is to provide a liquid crystal optical element that solves these problems.

[0009]

Means for Solving the Problems The present inventors have set forth the aforementioned section.
As a result of diligent research to solve the problem,
When polymer resin is dispersed in the tick liquid crystal material,
Display image product even if the applied or non-applied state lasts for a long time
To obtain a liquid crystal optical element that does not deteriorate
Was. That is, the present invention is as follows. 1 At least one of two transparent substrates with electrodes,
A switch in which the optical axis of the liquid crystal layer changes continuously with applied voltage.
100 parts by weight of a mectic liquid crystal material and 0.
The light control layer consisting of 01 to 10 parts by weight is sandwichedYou
And the smectic liquid crystal material is an antiferroelectric liquid.
Composed of crystalline material and liquid crystal material having smectic C phase
is being doneA liquid crystal optical element characterized by the above-mentioned. 2The polymer resin is contained in the smectic liquid crystal material.
3. The liquid crystal according to the above 1, wherein the liquid crystal exists in a three-dimensional shape.
Optical element.  3Characterized by having active elements on a substrate with electrodes
3. The liquid crystal optical element according to the above 1 or 2.  4At least one of the two transparent substrates with electrodes,
A switch in which the optical axis of the liquid crystal layer changes continuously with applied voltage.
100 parts by weight of mectic liquid crystal material and polymer resin 0.0
A light control layer consisting of 1 to 10 parts by weight,
And the smectic liquid crystal material is an antiferroelectric liquid crystal material.
And a liquid crystal material having a smectic C phase
In the method of manufacturing a liquid crystal optical element, a smectic
100 parts by weight of liquid crystal material and the polymer resin at normal temperature and pressure
0.01 to 10% by weight of precursor showing liquid or liquid crystal phase
And the polymer resin after mixing and sandwiching between the substrates
A production method characterized by polymerizing a precursor.  5That the polymerization of the polymer resin precursor is photopolymerization
5. The manufacturing method according to the above 4, wherein the method is characterized in that:  6The smear during photopolymerization of the polymer resin precursor
The phase of the optic liquid crystal material is
Anything between the continuously changing phase and the isotropic phase
The product according to claim 4 or 5, wherein
Construction method.  7During the photopolymerization of the polymer resin precursor, the smecte
Liquid crystal material phase That it is mectic A phase
The method according to claim 4, 5 or 6, wherein:

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The smectic liquid crystal material of the present invention may be any smectic liquid crystal material in which the optical axis of the liquid crystal layer changes continuously with applied voltage. It is desirable that the optical axis of the layer changes continuously with applied voltage. More specifically, the smectic liquid crystal material of the present invention is preferably formed by mixing an antiferroelectric liquid crystal material and a liquid crystal material having a smectic C phase. In the liquid crystal material obtained by the above-described mixing, spontaneous polarization can be suppressed low, so that a large charge is not required at the time of driving, and T
It is possible to drive the active element such as the FT without burdening the active element.

The antiferroelectric liquid crystal material of the present invention may be any liquid crystal material having an antiferroelectric phase in any of the phase series. The antiferroelectric liquid crystal material may be a single component or a mixed material of two or more compounds.

The liquid crystal material having a smectic C phase to be mixed with the antiferroelectric liquid crystal material of the present invention may be any liquid crystal material having a smectic C phase in a phase series. In addition, the liquid crystal material having the smectic C phase may be a single component or a mixed material of two or more compounds. However, the phase series of the liquid crystal material having the smectic C phase is the same as the crystal phase from the low temperature side.
Desirably, the smectic C phase-nematic phase-isotropic phase. A single component may be a compound showing a phase sequence different from the above-mentioned phase sequence, as long as it shows the above-mentioned phase sequence when used as a mixed material of two or more compounds.

Further, the present invention can be realized by using a liquid crystal material having a ferrielectric phase instead of the antiferroelectric liquid crystal material. That is, in the invention of Item 3, the smectic liquid crystal material may be composed of a liquid crystal material having a ferrielectric phase and a liquid crystal material having a smectic C phase.

In the present invention, the optical axis of the liquid crystal layer is not the optical axis of each liquid crystal molecule but the direction in which the refractive index of the entire liquid crystal layer is the maximum. In a liquid crystal, the optical axis is in two directions substantially perpendicular to the optical axis direction. It has a smaller refractive index than the refractive index in the optical axis direction. As a result, the entire liquid crystal layer has birefringence, and the direction of the optical axis changes by application of an electric field, thereby obtaining an electro-optical effect.

The polymer resin used for the light control layer of the liquid crystal optical element of the present invention may be one obtained by polymerizing only one of the following polymer resin precursors alone, or two or more of them. It may be a copolymer of compounds. As the other polymer resin precursor, any polymer precursor having a usual polymerizable group such as an acryloyl group and a vinyl group can be used. As the polymer resin precursor used in the present invention, 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, isoamyl acrylate, isobornyl acrylate, isodecyl acrylate, lauryl acrylate , Morpholine acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol Acrylate, isoamyl acrylate, tetrafluoroethylene furfuryl acrylate, 2,2,2-trifluoroethyl acrylate,
Monofunctional acrylate compounds such as 2,2,3,3,3-pentafluoropropyl acrylate, 2- (perfluorobutyl) ethyl acrylate, 2- (perfluorodecyl) ethyl 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, isobornyl methacrylate, isodecyl methacrylate, lauryl methacrylate, morpholine methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, 2,2,2-trifluoroethyl methacrylate, 2,2 Monofunctional methacrylate compounds such as 2,3,3,3-pentafluoropropyl methacrylate, 2- (perfluorobutyl) ethyl methacrylate, 2- (perfluorohexyl) ethyl methacrylate, 2- (perfluorodecyl) ethyl 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, trimethylol Propane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, urethane acrylate oligomer, dimethylol tricyclodecane diacrylate, 4,4 '
-Biphenol bis acrylate, 1,4-dihydroxybenzene bis acrylate, 4,4'-dihydroxy diphenyl ether bis acrylate, 4,4'-dihydroxy diphenyl methane bis acrylate, 2,2-
Bis (4-hydroxyphenyl) propane bisacrylate, meso-hexestrol bisacrylate, α,
α'-bis [4-hydroxyphenyl] -1,4-dipropylbenzenebisacrylate, 2,3,5,6-
Tetrafluorophenylene-1,4′-diol diacrylate, 2,2-bis (4-hydroxyphenyl) hexafluoropropane bisacrylate, 2,2 ′,
3,3 ′, 5,5 ′, 6,6′-octafluoro-4
4'-biphenol bisacrylate, 4,4'-diacryloyloxystilbene, 4,4'-diacryloyloxydiethylstilbene, 4,4'-diacryloyloxydipropylstilbene, 4,4'-diacryloyloxydibutylstilbene , 2,2,3,3,4,
4-hexafluoro-1,5-pentanediol diacrylate, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol diacrylate, benzene-1,3,5-triol triacrylate Acrylate, 1,
Polyfunctional acrylate compounds such as 1,1-tris [4-hydroxyphenyl] ethane triacrylate, 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 dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, pentaerythritol trimethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol Hexamethacrylate, dipentaerythritol monohydroxypentamethacrylate, urethane methacrylate oligomer, dimethylol tricyclodecane dimethacrylate, 4,4′-biphenol bismethacrylate,
1,4-dihydroxybenzenebismethacrylate,
4,4′-dihydroxydiphenyl ether bismethacrylate, 4,4′-dihydroxydiphenylmethanebismethacrylate, 2,2-bis (4-hydroxyphenyl) propanebismethacrylate, meso-hexestrol bismethacrylate, α, α′-bis [ 4-hydroxyphenyl] -1,4-dipropylbenzenebismethacrylate, 2,3,5,6-tetrafluorophenylene-1,4′-dioldimethacrylate, 2,2
-Bis (4-hydroxyphenyl) hexafluoropropanebismethacrylate, 2,2 ', 3,3', 5
5 ', 6,6'-octafluoro-4,4'-biphenol bismethacrylate, 4,4'-dimethacryloyloxystilbene, 4,4'-dimethacryloyloxydiethylstilbene, 4,4'-dimethacryloyloxy Dipropylstilbene, 4,4'-dimethacryloyloxydibutylstilbene, 2,2,3,3,4,4
-Polyfunctional methacrylate compounds such as hexafluoro-1,5-pentanediol dimethacrylate, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol dimethacrylate, styrene, aminostyrene, Examples include, but are not limited to, vinyl acetate.

It is necessary that the polymer resin is contained in an amount of 0.01 to 10.0 parts by weight based on 100 parts by weight of the liquid crystal material. Preferably 0.1 parts by weight or more, 5
It is not more than 1 part by weight, more preferably not less than 1 part by weight and not more than 3 parts by weight. If the amount is too small, the effect of suppressing the change over time of the electro-optical characteristics is reduced. If the amount is too large, a reduction in response speed due to hindering the electric field response of the liquid crystal material and a decrease in contrast due to significantly disturbing the alignment of the liquid crystal material are confirmed.
In addition, the hysteresis increases, that is, the curve of the light transmittance with respect to the applied voltage largely shifts between the step-up side and the step-down side, and the memory property appears.

The polymer resin precursor preferably exhibits a liquid or liquid crystal phase at room temperature and pressure and does not phase separate from the liquid crystal material at room temperature. However, the polymer resin precursor is converted into a liquid crystal material at a temperature at which the smectic liquid crystal material becomes an isotropic phase. It may be one that is uniformly mixed and does not phase separate from the liquid crystal material at the polymerization temperature.

Examples of the method for polymerizing the polymer resin precursor include a photopolymerization method and a heat polymerization method, and the photopolymerization method is preferred. As a light source used in the photopolymerization method of the polymer resin precursor, an electron beam or ultraviolet light can be used. When performing photopolymerization by ultraviolet rays, 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-
2-methylpropan-1-one, 2-methyl-1- [4
Acetophenone such as-(methylthio) phenyl] -2-morpholinopropane-1, benzoin such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal; benzophenone; benzoyl benzoic acid; 4-phenylbenzophenone; Benzophenones such as 3,3-dimethyl-4-methoxybenzophenone, thioxanthone,
Thioxanthone, such as 2-methylthioxanthone, diazonium salt, sulfonium salt, iodonium salt,
Known materials such as selenium salts can be used.

The photopolymerization initiator may be a solid or a liquid, but is preferably dissolved or compatible with the liquid crystal in view of the uniformity of the device. The initiator concentration is 30% by weight of the polymer precursor
The following is preferred. If necessary, a photopolymerization initiation aid such as methyldiethanolamine or 4-dimethylaminobenzoic acid may be added.

The photopolymerization of the polymer resin precursor is desirably performed at a higher temperature than the phase in which the optical axis of the liquid crystal layer changes continuously with applied voltage and at a lower temperature than the isotropic phase. Further, in a liquid crystal material having a smectic A phase in the phase series of the smectic liquid crystal material, it is desirable to perform photopolymerization in the smectic A phase. If the polymer resin precursor is photopolymerized in an isotropic phase or a phase in which the optical axis of the liquid crystal layer changes continuously with applied voltage, the alignment state of the liquid crystal material is easily disturbed, and the contrast of the liquid crystal optical element is reduced. This is not preferable because the light transmittance curve with respect to the voltage on the step-up side and the voltage on the step-down side do not match.

The liquid crystal optical element of the present invention is manufactured by sandwiching a mixture of a non-smectic smectic liquid crystal material and a polymer resin precursor between substrates having a fixed interval, and irradiating the mixture with the light. At this time, the mixture may be injected under reduced pressure or normal pressure. If necessary, heating may be performed.

As the material of the substrate used in the present invention, glass, plastic, metal and the like can be used. Coloring can be achieved by using a substrate having a color filter, or by dispersing a pigment or a dye in the substrate.

The substrate is set so that the electrode is on the light control layer side. As the electrode, a material such as ITO can be used, but if the substrate used has conductivity, the substrate can also be used as an electrode. The electrodes are placed in close contact with the light control layer.

These substrates with electrodes are desirably treated so that liquid crystals are aligned. At this time, it is desirable that both substrates have a homogeneous orientation, but other orientations may be used depending on the application. For this alignment treatment, a normal alignment film such as polyimide used for TN liquid crystal, STN liquid crystal or the like can be used, but one having a particularly low pretilt angle is desirable.

The alignment film of polyimide or the like may be of a soluble type in which polyimide or the like is dissolved in a solvent, or may be of a fired type in which the polyimide is formed by firing. It is desirable to perform an alignment treatment such as rubbing.

For setting the distance between the substrates, a rod-shaped or spherical spacer made of glass or a polymer resin or the like used in ordinary liquid crystal devices can be used, and the distance is desirably about 1 μm to 4 μm.

As a driving method of the present liquid crystal compound, active matrix driving in which an active element is incorporated in an electrode is desirable, but simple matrix driving may be performed according to the application. Active devices include thin-film transistors (TFTs)
Elements, metal-insulator-metal (MIM) elements, and the like, but are not limited thereto.

The liquid crystal optical element of the present invention can be applied not only to a light transmission type in which a light control layer is sandwiched between two transparent substrates having electrodes but also to a light reflection type in which one substrate is opaque. . For example, there are an element structure in which a light modulating layer is sandwiched between a transparent substrate having electrodes and a light reflecting plate having electrodes, and an element structure in which a light modulating layer is sandwiched between a transparent substrate having electrodes and a light absorbing plate having electrodes.

The light reflecting plate may be made of an inorganic material or an organic material as long as it is made of a material that reflects light. Further, the reflection intensity or the reflection wavelength can be arbitrarily changed according to the target device characteristics. The structure may be such that the light reflecting material forms the entire light reflecting plate, or the light reflecting material may be coated on the substrate with another material such as glass.
When a light reflecting material is coated, the light reflecting material does not need to be on the light control layer side. The substrate on which the light reflecting material is coated is not necessarily required to be transparent when the light reflecting material is not located on the light control layer side.

The light absorbing plate may be an inorganic material or an organic material as long as it is made of a material that absorbs light. The absorption intensity or absorption wavelength can be arbitrarily changed depending on the target device characteristics. In the structure, the light absorbing material may form the entire light absorbing plate, or the light absorbing material may be coated on the substrate with another material such as glass. When the light absorbing material is coated, the light absorbing material does not need to be on the light control 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 reflecting material or the light absorbing material has conductivity, these can also be used as electrodes.

As a use of the liquid crystal optical element of the present invention, there is a display material for displaying a building material such as a window or a partition, a character or a figure.

[0033]

EXAMPLES 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.

The driving voltage, contrast, and response speed described in the embodiments are defined as follows.

Driving voltage: When the lowest light transmittance in the applied voltage-light transmittance curve is 0% (minimum transmittance) and the light transmittance saturated by voltage application is 100% (maximum transmittance), the device Is a voltage at which the light transmittance becomes 90%.

Contrast: A value obtained by dividing light transmittance (maximum transmittance) saturated by voltage application by minimum transmittance.

Response speed: When a voltage at which the light transmittance is saturated is applied from the state where no voltage is applied, the light transmittance is 0% to 90%.
And the time required for the light transmittance to change from 90% to 0%.

Example 1 A mixture of compound (II) and (III) (((II): (I)) was added to 30 parts by weight of the following antiferroelectric liquid crystal material (1).
II) = 34: 66 (weight ratio)) and 70 parts by weight of a liquid crystal material (IV) having a smectic C phase was added to obtain a smectic liquid crystal material (A).

[0039]

Embedded image 99 parts by weight of smectic liquid crystal material (A), dimethylol tricyclodecane diacrylate represented by the following formula (V) as a polymer resin precursor

[0040]

Embedded image A mixture of 1 part by weight of a mixture of 2,2-diethoxyacetophenone and 2,2-diethoxyacetophenone as a polymerization initiator (the polymerization initiator was 5% by weight based on the polymer resin precursor) was heated to 90 ° C., and sufficiently stirred. The mixture was injected into a liquid crystal cell having a gap of 2 μm and consisting of two glass substrates with electrode layers which had been heated to 90 ° C. and had been subjected to a homogeneous alignment treatment. The liquid crystal cell is gradually cooled to 65 ° C. at a rate of 1 ° C. per minute, and while maintaining the temperature, ultraviolet rays of 0.05 mW / cm ² (wavelength 365 nm)
For 360 minutes to polymerize the polymer resin precursor. Thereafter, the liquid crystal cell was sandwiched between two orthogonal polarizing plates arranged so as to be in a normally black mode, to obtain a liquid crystal optical element.

The produced liquid crystal optical element was immediately (initial) applied with a triangular wave of ± 6 V, 0.1 Hz for 8 hours (applied for 8 hours) and allowed to stand without application for 10 days (1).
(Leaving for 0 days) and its electro-optical properties were measured and are shown in Table 1. Electro-optical characteristics were measured using a helium-neon laser as a light source and a photodiode as a detector for 0.1H.
The measurement was performed at 25 ° C. by applying a z-triangular wave.

[0042]

[Table 1] 4 and 5 are graphs showing the relationship between the applied voltage and the light transmittance in the initial stage of preparation of the liquid crystal optical element of Example 1 and the liquid crystal optical element of Comparative Example 1 to be described next, applied for 8 hours, and allowed to stand for 10 days.
And 6.

Comparative Example 1 A liquid crystal optical element was produced in the same manner as in Example 1 except that the polymer resin precursor and the polymerization initiator were not added, and the same characteristics as in Example 1 were measured. Are shown in Table 2.

[0044]

[Table 2] Example 2 Example 1 was repeated except that 2,2,3,3,4,4-hexafluoro-1,5-pentadiol diacrylate represented by the following formula (VI) was used as the polymer resin precursor.
A liquid crystal optical element was prepared and evaluated under the same conditions as those described above, and the results are shown in Table 3.

[0045]

Embedded image

[0046]

[Table 3] Example 3 The following liquid crystal materials (VII) and (VIII) were added to the antiferroelectric liquid crystal material (I) used in Example 1 (I):
(VII): (VIII) = 40: 40: 20 (weight ratio), and added to a smectic liquid crystal material (B).
I got

[0047]

Embedded image A liquid crystal optical element was produced and evaluated under the same conditions as in Example 1 except that the smectic liquid crystal material (B) was used instead of the smectic liquid crystal material (A). The results were shown in Table 4.

[0048]

[Table 4] Example 4 To 20 parts by weight of the antiferroelectric liquid crystal material (VII) used in Example 3, 80 parts by weight of the liquid crystal material (IV) having the smectic C phase used in Example 1 was added. C) was obtained.

98 parts by weight of a smectic liquid crystal material (C), and a polymer resin precursor represented by the following formula (IX)

[0050]

Embedded image A mixture of 1,4-phenylenebis {4- [6- (acryloyloxy) hexyloxy] benzoate} and benzoin methyl ether as a polymerization initiator
A mixture of 2 parts by weight (a polymerization initiator is 5 parts by weight with respect to the polymer resin precursor) is heated to 100 ° C., sufficiently stirred, and then heated to 100 ° C. in advance to obtain two homogeneously oriented electrode layers. It was injected into a liquid crystal cell having a gap of 2 μm made of a glass substrate provided with. The liquid crystal cell is cooled to 60 ° C. at a rate of 0.5 ° C./min, and while maintaining the temperature, ultraviolet rays of 0.05 mW / cm ² (wavelength 365 nm)
For 240 minutes to polymerize the polymer resin precursor. Thereafter, the liquid crystal cell was sandwiched between two orthogonal polarizing plates arranged so as to be in a normally black mode, to obtain a liquid crystal optical element.

The characteristics of the manufactured liquid crystal optical element were measured in the same manner as in Example 1, and the results are shown in Table 5.

[0052]

[Table 5] Example 5 97 parts by weight of the smectic liquid crystal material (C) used in Example 4 and 4,4-diacryloyloxydiethylstilbene represented by the following formula (X) as a polymer resin precursor

[0053]

Embedded image A liquid crystal optical element was manufactured under the same conditions as in Example 4 except that a mixture of 3 parts by weight of a mixture of benzoin methyl ether and benzoin methyl ether as a polymerization initiator (the polymerization initiator was 5 parts by weight with respect to the polymer resin precursor) was used. The results were evaluated and the results are shown in Table 6.

[0054]

[Table 6]

[0055]

According to the liquid crystal optical element of the present invention, the electro-optical characteristics are hardly deteriorated even when the voltage is continuously applied for a long time or when the voltage is not applied for a long time. In this case, the quality of the displayed image can be kept good for a long time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of the structure of a liquid crystal optical element of the present invention.

FIG. 2 is a cross-sectional view schematically illustrating an example of the structure of a conventional liquid crystal optical element.

FIG. 3 is a schematic cross-sectional view showing an example of the structure of a liquid crystal optical element before polymerization of a polymer resin precursor in the production method of the present invention.

FIG. 4 is a graph showing an example of a relationship between an applied voltage and light transmittance in an initial stage of preparation of the liquid crystal optical element of the present invention and a conventional liquid crystal optical element.

FIG. 5 is a graph showing an example of a relationship between an applied voltage and a light transmittance of the present invention and a conventional liquid crystal optical element after applying a voltage for 8 hours.

FIG. 6 is a graph showing an example of a relationship between an applied voltage and a light transmittance of the present invention and a conventional liquid crystal optical element after standing for 10 days.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Electrode 3 Alignment film 4 Smectic liquid crystal material 5 Polymer resin 6 Dimming layer 7 Polarizing plate 8 Polymer resin precursor

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaharu Sato 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (72) Inventor Yasuharu Onishi 5-7-1 Shiba, Minato-ku, Tokyo NEC (56) References JP-A-5-202358 (JP, A) JP-A-5-307170 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1334 G02F 1/141

Claims (7)

(57) [Claims] 1. A method according to claim 1, wherein at least one of the two substrates with electrodes is transparent, and 100 parts by weight of a smectic liquid crystal material whose optical axis continuously changes with applied voltage; A light modulating layer of 10 parts by weight is sandwiched , and the smectic liquid crystal material is
Dielectric liquid crystal material and liquid crystal material having smectic C phase
The liquid crystal optical element characterized by being composed. 2. A method according to claim 1, wherein the polymeric resin is present in the three-dimensional shape in the smectic liquid crystal material
The liquid crystal optical element according. 3. A liquid crystal optical element according to claim 1, wherein it has an active element in the electrode-attached substrate. 4. A method according to claim 1, wherein at least one of the two transparent substrates is provided with 100 parts by weight of a smectic liquid crystal material in which the optical axis of the liquid crystal layer changes continuously with applied voltage and 0.01 to 10 parts of a polymer resin. Ri Na by sandwiching the composed light control layer and a part by weight, and the smectic liquid crystal material, an antiferroelectric
Liquid crystalline materials and liquid crystal materials with smectic C phase
In the method for manufacturing a liquid crystal optical element, 100 parts by weight of a smectic liquid crystal material and 0.01 to 10 parts by weight of a precursor of the polymer resin which exhibits a liquid or liquid crystal phase at room temperature and normal pressure are mixed. A production method characterized by polymerizing the polymer resin precursor after being sandwiched between the two. 5. The method according to claim 4, wherein the polymerization of the polymer resin precursor is photopolymerization. 6. A phase of the smectic liquid crystal material at the time of photopolymerization of the polymer resin precursor, wherein the phase exists between a phase in which an optical axis changes continuously with an applied voltage and an isotropic phase. claim, characterized in that a phase 4 or 5
The manufacturing method as described. 7. A the time photopolymerization of polymer resin precursor according to claim 4, 5 or 6 manufacturing method, wherein a phase of the smectic liquid crystal material is a smectic A phase.