JP2010145727A - Optical modulator element and method of driving the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical modulator element capable of adjusting the viewing angle width, and its drive method. <P>SOLUTION: The optical modulator element has a pair of substrates 11, 21 with at least one of them having light transmissivity, a first and second dimmer layers 30A, 30B containing liquid crystals in the area between those substrates 11, 21, an electrode layer 22 to apply a voltage at least to the first dimmer layer 30A, and a controller 60 to regulate the voltage to be applied to the first dimmer layer 30A from the electrode layer 22. The optical modulator element drive method controls the domain sizes of the liquid crystals contained in the first dimmer layer 30A by regulating the voltage to be applied to the first dimmer layer 30A from the electrode layer 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light modulation element and a method for driving the light modulation element.

  Consumption of a large amount of paper, especially in offices, has become a problem due to destruction of forest resources, which are raw materials for paper pulp, waste disposal, and environmental pollution caused by incineration. However, with the spread of personal computers and the development of the information society such as the Internet, the consumption of paper as a so-called short-lived document for the purpose of temporary browsing of electronic information tends to increase more and more. It is desired to realize a rewritable display medium that can replace the above.

  By the way, the cholesteric light modulation element has a memory property that can hold a display with no power supply, a bright display can be obtained because a polarizing plate is not used, and a color display can be performed without using a color filter. That has attracted attention in recent years.

  A cholesteric liquid crystal in which liquid crystal molecules have a spiral structure divides incident light into right circularly polarized light and left circularly polarized light, causes a circularly polarized component in the twisted direction of the spiral to Bragg, and causes a selective reflection phenomenon that transmits the remaining light. The center wavelength λ of reflected light and the reflected wavelength width Δλ are expressed as λ = n · p and Δλ = Δn · p, respectively, where the helical pitch is p, the average refractive index is n, and the birefringence is Δn. The reflected light from the liquid crystal layer exhibits a vivid color depending on the helical pitch.

  As shown in FIG. 3A, the cholesteric liquid crystal having positive dielectric anisotropy has a planar state in which the spiral axis is perpendicular to the cell surface and causes the selective reflection phenomenon described above with respect to incident light. As shown in FIG. 3B, the helical axis is parallel to the cell surface and the incident light is transmitted while being slightly scattered forward, and as shown in FIG. Three states are shown: a homeotropic state in which the electric field direction is directed and incident light is transmitted.

  Of the above three states, the planar state and the focal conic state can exist bistable without voltage. Therefore, the alignment state of the cholesteric liquid crystal is not uniquely determined with respect to the voltage applied to the liquid crystal layer. When the planar state is the initial state, the planar state, the focal conic state, When the focal conic state is the initial state, the focal conic state and the homeotropic state are changed in this order as the applied voltage increases. On the other hand, when the voltage applied to the liquid crystal layer is reduced to zero, the planar state and the focal conic state are maintained as they are, and the homeotropic state is changed to the planar state. Then, the above three states can be shifted to each other depending on the height of the applied pulse voltage.

  This electro-optic response is shown in FIG. In FIG. 4, curve A shows the case where the initial state is the planar state, and curve B shows the case where the initial state is the focal conic state.

  In FIG. 4, the region indicated by (a) is a planar state or focal conic state (selective reflection state or transmission state), the region indicated by (b) is a transition region, and the region indicated by (c) is a focal conic state (transmission state). ), The region indicated by (d) indicates the transition region, the region indicated by (e) indicates the homeotropic state, and when the voltage is set to 0 in the homeotropic state, the region changes to the planar state (selective reflection state). In addition, Vpf, 90, Vpf, 10, Vfh, 10, Vh, 90 are voltages at which the normalized reflectance is 90 or 10 before and after the two transition regions (the normalized reflectance is 90 or more). It means a selective reflection state and 10 or less is a transmission state).

  A reflective memory display using a planar state and a focal conic state can be realized by disposing at least a layer that absorbs light having a wavelength of the selective reflection color on the back surface of the cholesteric liquid crystal layer.

  Cholesteric light modulators have a structure in which liquid crystal is sealed as a continuous phase between a pair of supporting substrates, PDLC (Polymer Dispersed Liquid Crystal) in which cholesteric liquid crystal is dispersed in a polymer binder in a drop shape, There is known a display method called PDMLC (Polymer Dispersed Microencapsulated Liquid Crystal) in which liquid crystal microencapsulated liquid crystal is dispersed (see, for example, Patent Documents 1 to 3).

Here, a liquid crystal element in which a monodomain and a polydomain are mixed is disclosed as a method for widening the viewing angle without reducing the color purity (see, for example, Patent Document 4). Specifically, a polydomain is arranged on the visual field side, and a monodomain is arranged on the opposite side.
Japanese Patent Publication No. 7-009512 JP 09-236791 A Japanese Patent No. 3178530 Japanese Patent No. 3386055

  An object of the present invention is to provide a light modulation element capable of adjusting the width of the viewing angle and a method for driving the light modulation element.

The above-mentioned subject is achieved by the following present invention.
That is, the invention according to claim 1 of the present invention is
At least one has a pair of translucent substrates,
And it has the 1st light control layer and the 2nd light control layer containing a liquid crystal, and the electrode layer which applies a voltage to at least the 1st light control layer in the field between the pair of substrates. With
It is a light modulation element which has a control part which controls the height of the applied voltage applied to the 1st light control layer from the electrode layer.

The invention according to claim 2
At least one has a pair of translucent substrates,
In a region sandwiched between the pair of substrates, the first electrode layer, the first light control layer, the intermediate layer, the second light control layer, and the second electrode layer are provided. Have in order,
2. The light modulation element according to claim 1, further comprising a control unit configured to control a height of an applied voltage applied from the first electrode layer to the first light control layer.

The invention according to claim 3
At least one has a pair of light-transmitting substrates, and a first light control layer and a second light control layer containing liquid crystal in a region sandwiched between the pair of substrates, and at least the first light control layer An electrode layer for applying a voltage to the light control layer,
It is a method for driving a light modulation element that controls the domain size of the liquid crystal contained in the first light control layer by adjusting the height of an applied voltage applied from the electrode layer to the first light control layer. .

The invention according to claim 4
At least one has a pair of light-transmitting substrates, and a region sandwiched between the pair of substrates includes a first electrode layer, the first light control layer, an intermediate layer, and the second layer. For the light modulation element having the light control layer and the second electrode layer in this order,
4. The domain size of the liquid crystal contained in the first light control layer is controlled by adjusting a height of an applied voltage applied from the first electrode layer to the first light control layer. 5. This is a method of driving the light modulation element.

  According to the first aspect of the present invention, the viewing angle can be adjusted.

  According to the invention which concerns on Claim 2, the breadth of a viewing angle can be adjusted more simply.

  According to the invention of claim 3, the width of the viewing angle can be adjusted.

  According to the invention which concerns on Claim 4, the breadth of a viewing angle can be adjusted more simply.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The light modulation element according to the present embodiment has a pair of substrates, at least one of which has translucency, and a first light control layer and a second liquid crystal containing liquid crystal in a region sandwiched between the pair of substrates. A light control layer and an electrode layer for applying a voltage to at least the first light control layer, and a control for controlling a height of an applied voltage applied from the electrode layer to the first light control layer It has the part.

  In addition, in the driving method of the light modulation element according to the present embodiment, at least one has a pair of light-transmitting substrates, and a first adjustment that includes liquid crystal in a region sandwiched between the pair of substrates. With respect to a light modulation element having a light layer and a second light control layer, and an electrode layer for applying a voltage to at least the first light control layer, the electrode layer applies the light to the first light control layer The domain size of the liquid crystal contained in the first light control layer is controlled by adjusting the height of the applied voltage.

  In conventional light modulation elements, increasing the domain size of the liquid crystal contained in the light control layer can achieve good color purity, but the viewing angle is narrowed. On the other hand, decreasing the domain size increases the viewing angle, but the color purity Had the problem of getting worse. On the other hand, as a method for widening the viewing angle without reducing the color purity, a light modulation element in which a monodomain and a polydomain are mixed has been proposed. However, the required viewing angle varies depending on the situation in which the light modulation element is used, and a light modulation element capable of adjusting the width of the viewing angle has been sought, but it has not been provided yet. Met.

On the other hand, the light modulation element according to the present embodiment includes a first light control layer and a second light control layer containing liquid crystal, and an electrode layer that applies a voltage to at least the first light control layer, And a controller that controls the height of the applied voltage applied from the electrode layer to the first light control layer. The control unit has a function of controlling a domain size of liquid crystal contained in the first light control layer by adjusting a height of an applied voltage applied from the electrode layer to the first light control layer. . As described above, the width of the viewing angle can be adjusted by controlling the domain size of the liquid crystal contained in the first light control layer.
As a result of intensive studies by the inventors, it has been found that the domain size of the liquid crystal can be controlled by controlling the height of the applied voltage applied to the liquid crystal contained in the light control layer. Specifically, the domain size of the liquid crystal is increased by increasing the applied voltage, while the domain size of the liquid crystal is decreased by decreasing the applied voltage. If the domain size of the liquid crystal is increased, the straight angle of light is increased and the viewing angle is narrowed. On the other hand, if the domain size of the liquid crystal is decreased, the straight angle of light is decreased and the viewing angle is widened. Thereby, according to this embodiment, it is guessed that the breadth of a viewing angle can be adjusted.

  In addition, in order to confirm the domain size of a liquid crystal, the method of measuring or confirming a domain size by microscopic observation is mentioned.

<First Embodiment>
Here, the light modulation element according to the first embodiment will be described as the configuration of the light modulation element according to the present embodiment. The light modulation element according to the first embodiment includes a first electrode layer and a liquid crystal containing a liquid crystal in a region sandwiched between the pair of substrates, at least one of which has a light-transmitting property. 1 light control layer, an intermediate layer, a second light control layer containing liquid crystal, and a second electrode layer in this order, and from the first electrode layer to the first light control layer And a control unit for controlling the magnitude of the applied voltage applied to the.

  In the light modulation element according to the first embodiment, the domain size of the liquid crystal contained in the first light control layer is controlled by the magnitude of the applied voltage. Specifically, the domain size of the liquid crystal contained in the first light control layer is controlled by controlling the magnitude of the applied voltage applied from the first electrode layer to the first light control layer. As a result, the width of the viewing angle can be adjusted.

In the light modulation device according to the first embodiment, the second light control layer may be configured such that the domain size of the contained liquid crystal is not adjusted by the magnitude of the applied voltage.
In addition, it is preferable to use a liquid crystal with a large domain size from the viewpoint of obtaining good color purity for the second light control layer.

In addition to this, the light modulation element of the present embodiment may be provided with a light shielding layer on the electrode of the substrate on the non-display surface side, if necessary. Further, the light shielding layer and the light control layer, the electrode and the light control layer, etc. May be provided via an adhesive layer.
The liquid crystal used in the light modulation element of this embodiment is cholesteric liquid crystal, nematic liquid crystal, guest / host liquid crystal, etc., without particular limitation. Hereinafter, cholesteric liquid crystal will be described as an example.

Next, the light modulation element according to the first embodiment will be described with reference to the drawings.
As shown in FIG. 1, the light modulation element 10 of the first embodiment includes a first adjustment liquid crystal containing liquid crystal in a region sandwiched between a pair of non-display surface substrates 11 and a display surface substrate 21 provided to face each other. An optical layer 30A and a second light control layer 30B are provided. The second electrode 12 is laminated on the non-display surface substrate 11, and the first electrode 22 is laminated on the display surface substrate 21.

  Although not shown, a light shielding layer may be provided on the non-display surface substrate 11, and the display surface substrate 21 and the light control layer 30A are laminated via an adhesive layer. Also good. The electrode 22, the light control layer 30A, the electrode 12, the light shielding layer, and the like may be provided via an adhesive layer. Further, the light shielding layer may be provided outside the non-display surface substrate 11, that is, on the side where the electrode 12 is not formed, or in a region sandwiched between the electrode 22 and the light control layer 30A on the display surface substrate 21 side. Good.

  In the light modulation element 10 configured as described above, the alignment state of the cholesteric liquid crystal is controlled according to the applied voltage by adjusting the applied voltage applied to the voltage from the control unit 60 to the opposing electrode 22 and the electrode 12. The incident light incident on the light control layers 30A and 30B is selectively reflected by the cholesteric liquid crystal.

Next, each component used for the light modulation element described above will be described.
-Board-
The substrate is formed of glass and silicone having an insulating property, or a polymer film such as polyethylene terephthalate, polysulfone, polyethersulfone, or polycarbonate, and at least one of the substrates that is particularly visually recognized (display surface substrate). Is formed of a material that is transparent to incident light and reflected light. Moreover, you may form well-known functional films, such as a pollution protection film, an abrasion-resistant film | membrane, a light reflection prevention film, and a gas barrier film, on the surface of a support substrate as needed.

-Electrode-
The electrode is formed using a conductive metal thin film such as gold or aluminum, a metal oxide such as indium oxide or tin oxide, or a conductive organic polymer such as polypyrrole, polyacetylene, or polyaniline, at least on the display surface side. The electrode is formed of a material that is transparent to incident light and reflected light. Moreover, you may form well-known functional films, such as an adhesive force improvement film | membrane, a light reflection prevention film | membrane, and a gas barrier film, on the surface as needed.

-Light control layer-
The light control layer contains a liquid crystal. The layer thickness of the light control layer is preferably 1 μm or more and 100 μm or less.

(liquid crystal)
The liquid crystal material that can be used in the first embodiment may be any liquid crystal material as long as it has a refractive index anisotropy and the orientation changes upon application of voltage, but preferably a cholesteric liquid crystal (chiral). A nematic liquid crystal).

  The cholesteric liquid crystal material used in the first embodiment is a steroidal cholesterol derivative, or a Schiff base, azo, azoxy, benzoate, biphenyl, terphenyl, cyclohexylcarboxylate, phenylcyclohexane. , Biphenylcyclohexane, pyrimidine, dioxane, cyclohexylcyclohexane ester, cyclohexylethane, cyclohexane, tolan, alkenyl, stilbene, condensed polycyclic nematic liquid crystals, smectic liquid crystals, or mixed liquid crystals thereof In addition, a material to which a chiral component made of an optically active material such as Schiff base, azo, ester, or biphenyl is added can be used.

The liquid crystal contained in the first light control layer in the first embodiment should have a high resistance value from the viewpoint that the domain size can be easily controlled by the applied voltage, and preferably the second light control layer. The resistance value is preferably three times or more.
On the other hand, as the liquid crystal contained in the second light control layer in the first embodiment, it is preferable to use a liquid crystal having a large domain size from the viewpoint of obtaining good color purity. As a preferable liquid crystal, it is preferable that the refractive index anisotropy is large and the resistance value is lower than that of the first light control layer.

-Intermediate layer-
The intermediate layer is a layer interposed so that an applied voltage applied from the first electrode layer to the first dimming layer does not affect the second dimming layer, and the second electrode layer To the second light control layer is an intervening layer so that the applied voltage applied to the second light control layer does not affect the first light control layer.
As the material of the intermediate layer, for example, a known transparent substrate such as glass or plastic is used, and a flexible substrate including a polyester film such as polyethylene terephthalate is applied.
The thickness of the intermediate layer is preferably from 0.1 μm to 10 μm.

-Adhesive layer-
For the adhesive layer, a material that can adhere the light control layer and the light shielding layer by heat or pressure, such as urethane resin, epoxy resin, acrylic resin, or silicone resin, is used. The position where the adhesive layer is inserted is not limited to this embodiment, and an electrode and a light control layer, an electrode and a light shielding layer, and the like may be provided via the adhesive layer. In the case where the electrode and the light control layer are provided via an adhesive layer, the electrode and the light control layer are formed of a material that is transparent to at least incident light and reflected light.

-Light shielding layer-
The light shielding layer is an insulating cadmium-based, chromium-based, cobalt-based, manganese-based, carbon-based inorganic pigment, or azo-based, anthraquinone-based, indigo-based, triphenylmethane-based, nitro-based, phthalocyanine-based, perylene. , Pyrrolopyrrole, quinacridone, polycyclic quinone, squalium, azurenium, cyanine, pyrylium, anthrone, and other organic dyes and pigments, or materials dispersed in gelatin , At least with respect to the reflected light.

-Photoconductive layer-
The photoconductive layer is composed of a-Si: H, a-Se, Te-Se, As ₂ Se ₃ , CdSe, CdS.
Inorganic photoconductors such as azo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, pyrrolopyrrole pigments, indigo pigments, anthrone pigments, and charge transport materials such as arylamines, hydrazones, triphenylmethane, and PVK It is composed of an organic photoconductor combined with the above.

Next, a method for manufacturing the light modulation element of the first embodiment will be described. In the first embodiment, in order to simplify the description, as shown in FIG. 1, dimming including a liquid crystal drop in a region sandwiched between the non-display surface substrate and the display surface substrate provided to face each other. A case where a layer is provided will be described.
In the method of manufacturing the light modulation element according to the first embodiment, a light-shielding layer is laminated on a non-display surface substrate as a support substrate having electrodes on the surface, and then a second light control layer is further laminated. After laminating the first light control layer on the display surface substrate as the support substrate having the electrode, the display surface substrate as the support substrate having the electrode on the surface is disposed on the surface and the surface where the electrodes are formed via the intermediate layer. The non-display surface substrate as the supporting substrate having the electrodes is manufactured by overlapping and bonding so that the surface on which the electrodes are formed faces each other.

Next, a method for producing the light control layer of the light modulation element will be described.
In addition, although the 1st light control layer and the 2nd light control layer may respectively use the same liquid crystal, gelatin, a crosslinking agent, a solvent, etc., or different, the formation method of each light control layer Is the following: Therefore, in order to simplify the description, a case where the first light control layer is formed on the display surface substrate will be described as an example.
First, preparation of the light control layer coating solution will be described in detail.

[Preparation of light control layer coating solution]
The light control layer coating solution used in the first embodiment is prepared by dispersing liquid crystal drops or liquid crystal microcapsules in a solution containing gelatin, a crosslinking agent for crosslinking gelatin, and a liquid.
First, a method for preparing a liquid crystal drop and a liquid crystal microcapsule will be described.

<Preparation of liquid crystal drop emulsion>
The liquid crystal drop emulsion is prepared by emulsifying and dispersing a dispersed phase containing at least a cholesteric liquid crystal into a continuous phase that is incompatible with the dispersed phase, for example, an aqueous phase. As a means for emulsification, after mixing the dispersed phase and the continuous phase, a method of dispersing the dispersed phase as fine droplets by mechanical shearing force such as a homogenizer, or the dispersed phase is extruded through the porous film into the continuous phase. For example, a film emulsification method in which fine droplets are dispersed can be used. In particular, the membrane emulsification method is preferable because liquid crystal drops having a uniform particle diameter can be formed because the dispersion of the particle diameters of the emulsified droplets is small. A surfactant and a protective colloid for stabilizing the emulsification may be mixed in the continuous phase at the time of emulsification.

<Preparation of liquid crystal microcapsule slurry>
In preparing a liquid crystal microcapsule in which a cholesteric liquid crystal is encapsulated in a polymer shell, a known liquid crystal microencapsulation method such as a phase separation method, an interfacial polymerization method, or an in situ polymerization method can be used. Specifically, the liquid crystal drop produced as described above is dispersed in a solution containing a polymer shell material, or is thermoset according to the material to form a polymer shell around the liquid crystal drop. . Also, when making urethane / urea polymer shells, a polyisocyanate compound is added to the liquid crystal drop in advance, and the liquid crystal drop is added to a solution containing the polyhydric alcohol to generate a urethane / urea reaction. It is preferable to cause

  As the polymer shell, a material that does not dissolve in the encapsulated liquid crystal material is used. For example, gelatin, cellulose derivative, gelatin-gum arabic, gelatin-gellan gum, gelatin-peptone, gelatin-carboxymethylcellulose, polystyrene, polyamide, nylon, polyester, poly Examples include phenyl ester, polyurethane, polyurea, melamine formalin resin, phenol formalin resin, urea formalin resin, acrylic resin, and methacrylic resin.

  If the particle size of the liquid crystal microcapsules is too small, sufficient reflection characteristics cannot be obtained, which deteriorates display characteristics and lowers contrast. On the other hand, if the wall thickness of the liquid crystal microcapsule by the polymer shell is too thick, the amount of the liquid crystal material included in the liquid crystal microcapsule decreases, and if it is too thin, the strength decreases. Therefore, in order to suppress the decrease in strength with high contrast, the wall thickness of the liquid crystal microcapsule is preferably 1% or more and 25% or less of the radius of the liquid crystal microcapsule, and further within the range of 3% or more and 21% or less. It is preferable.

  The volume average primary particle size of the liquid crystal microcapsules and the liquid crystal drop is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 20 μm or less, and particularly preferably 10 μm or more and 15 μm or less. If the volume average primary particle size of the liquid crystal microcapsule and the liquid crystal drop exceeds 20 μm, the driving voltage increases, and if it is less than 3 μm, sufficient reflection characteristics may not be expected.

<Concentration>
If the non-volatile concentration of the liquid crystal drop emulsion or the liquid crystal microcapsule slurry after the above process is low and cannot be adjusted to the non-volatile concentration required for the light control layer coating liquid during application, concentration is performed. Using a liquid crystal drop or a difference in specific gravity between the liquid crystal microcapsule and the continuous phase, a method of removing by precipitation or sedimentation by standing or centrifuging, a method of filtering with a membrane filter, or the like is used.

<Preparation of coating solution for light control layer>
A liquid crystal drop emulsion or liquid crystal microcapsule slurry obtained as described above is dispersed in a solution containing gelatin, a crosslinking agent for crosslinking gelatin, and a solvent to prepare a light control layer coating solution.

(Preparation method of light control layer coating solution)
In the first embodiment, a liquid crystal drop or a liquid crystal microcapsule is applied on a support substrate. Therefore, using a density meter or a specific gravity meter, the content of each component in the liquid crystal drop emulsion or liquid crystal microcapsule slurry is measured, and the gelatin, solvent, and liquid crystal drop or liquid crystal microcapsule in the light control layer coating liquid are mixed. Adjust the percentage.

The ratio (volume ratio) of the non-volatile component volume to the coating liquid volume for the light control layer is Sr, the ratio (volume ratio) of the liquid crystal drop or liquid crystal microcapsule volume to the non-volatile component volume is Lr, and the average particle size of the liquid crystal drop or liquid crystal microcapsule diameter (μm) D _L, the wet coating thickness on the rear substrate ([mu] m) and t _W, the ratio a _L of coverage of liquid drops or a liquid crystal microcapsules in a coating area,

[formula]
A _L = (3/2) · (t _W · Sr · Lr / D _L ) (1)
It becomes. And A _L is

[formula]
0.8 <A _L <1.0 Formula (2)
It is preferable to adjust the coating liquid for coating light control layer so as to be in the range.
The Sr means Sr = Y / X when the non-volatile component remaining when the solvent is evaporated from the light control layer coating solution Xcc is Ycc, and a Zcc liquid crystal drop or liquid crystal microcapsule is included in the non-volatile component Ycc. If included, it means Lr = Z / Y.

In order to prevent breakage due to pressure or the like, the ratio (volume ratio) Lr of the volume of the liquid crystal drop or the liquid crystal microcapsule to the volume of the non-volatile component is preferably 0.9 or less.
Based on the calculated mixing ratio, the amount of gelatin, solvent, and crosslinking agent mixed in the liquid crystal drop emulsion or liquid crystal microcapsule slurry is adjusted to prepare a coating liquid for coating light control layer. Here, you may add well-known coating liquid characteristic modifiers for light control layers, such as a thickener, a wettability improving agent, and a drying rate modifier.

(solvent)
As the solvent contained in the light control layer coating liquid of the first embodiment, a solvent that dissolves gelatin and does not dissolve liquid crystal in the case of liquid crystal drop is used, and in the case of using liquid crystal microcapsules, at least the liquid crystal microcapsules are used. Those that do not dissolve the polymer shell are used.
Examples of the solvent include pure water, ion-exchanged water, distilled water, tap water, and the like, water-soluble organic solvents, or liquids obtained by mixing water such as ion-exchanged water, distilled water, and tap water with water-soluble organic solvents. A water-soluble organic solvent, an ionic liquid, etc. are selected according to a use, use conditions, etc.

  In 1st Embodiment, it is preferable that the said solvent contains 75 to 95 mass% with respect to the coating liquid for light control layers, and it is more preferable to contain 80 to 90 mass%. . When the content of the solvent is in the range of 75% by mass or more and 90% by mass or less, the viscosity can be adjusted so that the light control layer coating liquid can be applied.

<Method of forming light control layer>
Next, the process of providing the light control layer (1st light control layer as an example as mentioned above) of the light modulation element of 1st Embodiment is demonstrated.
The step of providing the light control layer of the light modulation element of the first embodiment is the same as the step of providing the light control layer of the light modulation element, comprising a solution containing gelatin, a crosslinking agent capable of crosslinking gelatin, and a solvent on the display surface substrate. A first coating step in which a liquid crystal drop or liquid crystal microcapsule dispersed liquid crystal coating liquid is coated on the substrate; and a solvent in the coating layer formed by the light control layer coating liquid coated on the substrate is gelatin It is evaporated and dried at a temperature higher than the freezing point, and the gelatin contained in the light control layer coating solution is crosslinked and crosslinked by the crosslinking agent, and the liquid for swelling the gelatin is dried and crosslinked by the crosslinking drying step. A second coating step for coating the coated layer, and a drying step for volatilizing and drying the liquid in the coated layer at a temperature below the freezing point of gelatin.
The process of providing this light control layer is demonstrated in detail below.

(First coating process)
The application of the light-adjusting layer coating solution with the concentration adjusted as described above to the display surface substrate is performed using a known apparatus that can be applied to a desired wet thickness such as an applicator, an edge coater, a screen coater, a roll coater, a curtain coater, and a die coater. To do.

  In the first coating step, it is necessary to heat the gelatin of the light control layer coating solution to a temperature higher than the melting point to maintain a fluid sol state. Gelatin becomes sol when heated to a temperature higher than the melting point and gels and loses fluidity when lowered to a temperature below the freezing point. Although it varies depending on the concentration and pH of the gelatin aqueous solution, the freezing point of commercially available gelatin is 20 ° C. or higher and 30 ° C. or lower, and the melting point is about 5 ° C. higher than that. For this reason, in a coating process, it is preferable to hold | maintain the light control layer coating liquid at the temperature of 20 degreeC or more and 80 degrees C or less of light control layer coating liquid temperature as a freezing point 20 degreeC or more. More preferably, it is preferably maintained at the temperature of the light control layer coating solution of 30 ° C. or more and 70 ° C. or less, and particularly preferably, it is maintained at the temperature of the light control layer of 40 ° C. or more and 60 ° C. or less. preferable. If the temperature of the coating liquid for the light control layer is less than 20 ° C., the gelatin cannot be made into a suitable viscosity because of insufficient sol formation, and if it exceeds 80 ° C., volatilization of the liquid crystal material occurs. There is a problem that the composition ratio of the liquid crystal compound is easily changed.

(Crosslinking drying process)
Next, the coating layer formed on the display surface substrate by the coating step is held in a sealed container, and the heating to the display surface substrate is continued to heat the coating layer to a temperature higher than the melting point. The coating layer is held under a temperature of 40 ° C. or more and 60 ° C. or less, and the coating layer is kept in the same atmosphere as the saturated vapor pressure in the coating layer or in an atmosphere close to the saturated vapor pressure of this solvent for 5 minutes. By continuing the heat treatment for 25 minutes or less, the solvent in the coating layer is volatilized and dried, and a cross-linking drying step is performed in which gelatin in the coating film is cross-linked with a cross-linking agent.

As a heating device for heating, an oven, a hot air blowing device, a hot plate, or the like can be used.
The coating layer temperature is preferably 20 to 80 ° C., particularly preferably 30 to 70 ° C., and more preferably 40 to 60 ° C. When the temperature exceeds 80 ° C., there is a problem that the composition ratio of the liquid crystal compound changes due to volatilization. When the temperature is less than 20 ° C., the viscosity in the coating layer is low, so the fluidity is low and liquid crystal drops or liquid crystal microcapsules are densely arranged. Since it becomes difficult to do, it is not preferable.

When drying under these conditions, the liquid crystal drops or liquid crystal microcapsules that have been dispersed naturally change into a dense state while gradually changing the positional relationship with the volatilization of the solvent contained in the light control layer coating liquid. I will do it.
If the movement of the liquid crystal drop or liquid crystal microcapsule is insufficient, the solvent can be completely removed by applying vibration, for example, mechanical vibration such as an ultrasonic vibrator, to the coating layer in part or all of the drying and crosslinking step. When it volatilizes, a liquid crystal drop or a liquid crystal microcapsule is densely arranged in a single layer, and the surface unevenness is small and a flat polymer dispersed light control layer can be obtained.

  Under conditions where the drying speed is too high, the liquid crystal drop or liquid crystal microcapsule tends to be distorted due to intense liquid flow at the dry end, and the alignment direction of the liquid crystal in the liquid crystal drop or liquid crystal microcapsule is on the support substrate surface. There is a tendency to tilt. For example, when a cholesteric liquid crystal is used, there is a problem that a large viewing angle dependency occurs in the selectively reflected light. Therefore, it is preferable to control rapid drying of the solvent by controlling mild drying conditions. In order to suppress abrupt solvent volatilization, the coating part may be held in an atmosphere whose vapor pressure is the same as or close to the saturated vapor pressure of the solvent contained in the light control layer coating solution. For this purpose, a method of holding the application part in a container having a volume as small as possible, a method of holding it in a chamber having a vapor generation part of the solvent, a method of reducing the saturated vapor pressure of the solvent to atmospheric pressure or the like, etc. Can be used.

  By being crosslinked and dried under high humidity, the gelatin contained in the coating layer is crosslinked by a crosslinking agent, and a coating layer in a sol state (crosslinked sol state) in which gelatin is crosslinked by the crosslinking agent is obtained.

(Second application process)
Next, the gelatin in the coating layer was cooled to a temperature below the freezing point of gelatin by cooling the display surface substrate, and the gelatin was brought into a crosslinked sol state by the above-described crosslinking drying step at a temperature below the freezing point of gelatin. A liquid for swelling the gelatin contained in the coating layer is applied to the coating layer.

In the second coating step, it is preferable that the display surface substrate is naturally cooled at room temperature or forcedly cooled using a cooling device so that the coating layer temperature is 30 ° C. or lower, which is below the freezing point of gelatin.
As a cooling device for cooling the display surface substrate, a cooling plate using a Peltier or the like, a cold air blowing device, or the like can be used.

The liquid to be applied to the coating layer in which the gelatin is in a crosslinked sol state may be any liquid that can swell the gelatin. Examples of the liquid include pure water, ion-exchanged water, distilled water, and tap water. A solvent, or a liquid obtained by mixing water such as ion-exchanged water, distilled water, or tap water with a water-soluble organic solvent, a water-insoluble organic solvent, an ionic liquid, or the like is selected according to the use or use conditions. In addition, a polymer material for adjusting viscosity may be added to a liquid capable of swelling gelatin. The polymer material may be anything as long as it does not contaminate or dissolve the coating layer in the crosslinked sol state, and examples thereof include gelatin and polyvinyl alcohol.
Furthermore, you may add well-known solution characteristic modifiers, such as a thickener, a wettability improving agent, and a drying rate modifier.

In the first embodiment, since the liquid needs a sufficient amount to change the sol-gel, it is applied on the coating layer at a ratio of 0.5 to 20 times the coating thickness. In particular, it is more preferably applied at a ratio of 1 to 10 times.
Application of the liquid to the application layer is performed using a known apparatus capable of applying a desired amount such as an applicator, an edge coater, a screen coater, a roll coater, a curtain coater, or a die coater. In the second coating step, the gelatin is applied to the coating layer in which the gelatin is in a crosslinked sol state, so that the gelatin in the coating layer absorbs the liquid and swells. Since it is performed under the following temperature, the gelatin in the coating layer is in a crosslinked gel state.

  Further, as a method other than the coating, it may be carried out using a known apparatus capable of causing a sol-gel change of gelatin in which the light control layer is sprayed with steam or the light control layer is stored in a high humidity state. . Thus, in the second coating step, when the gelatin in the sol state swells by absorbing the liquid, the gelatin is in a crosslinked state, so that the dense structure formed in this crosslinking and drying step is destroyed. The coating layer is swollen without. Moreover, since this swelling process is performed under the temperature below the freezing point of gelatin, gelatin changes from a sol state to a gel state.

Here, the gelatin and the crosslinking agent will be described.
-Gelatin-
As gelatin used for the light control layer of this embodiment, the thing with a large jelly strength and a low sol viscosity is preferable as a physical property of gelatin.

  As the gelatin, those having a high molecular weight β chain / γ chain which is a multimer of α chains and low molecular weight components in which the main chain of the α chain is cut off in the middle and a large amount of α chain remaining are suitable. A gelatin material produced by acid treatment of bovine bone is preferable because it satisfies this condition, and particularly has high jelly strength and low sol viscosity. Moreover, the 1st extract extracted first when hydrolyzing the collagen of a raw material is good. In order to prevent ionic contamination of the liquid crystal material, ionic components remaining in the gelatin may be removed using a known technique such as an ion exchange resin.

-Crosslinking agent-
The crosslinking agent contained in the light control layer coating liquid of the present embodiment and capable of crosslinking gelatin may be selected from those suitable in relation to gelatin, but among them, a crosslinking is formed between gelatin molecules, Those which make gelatin hardly soluble are preferred, such as formaldehyde, acetaldehyde, glutaraldehyde, and glyoxal of aldehyde compounds (compounds having an aldehyde group), potassium alum hydrate of polyvalent metal salt compounds, or adipic acid dihydrazide, Examples include melamine formalin oligomer, ethylene glycol diglycidyl ether, polyamide epichlorohydrin, polycarbodiimide, and the like.

  Among them, a compound having an aldehyde group (aldehyde compound) is preferable in that ionic impurities are not eluted into the cholesteric liquid crystal and the electric characteristics are not affected even if contained in the light control layer. The reason for this is that a compound having an aldehyde group is purified by oxidizing an alcohol, so that it is expected that an ionic substance is hardly mixed. Also, no by-product is generated from the reaction with the amino group of the gelatin molecule.

  Furthermore, with a monofunctional aldehyde compound (for example, formaldehyde), a sufficient crosslinking effect cannot be obtained, and in the polyfunctional aldehyde represented by the following general formula (1) (n is 0 or more), the functional group represented by n If the chain length is large, the opportunity for cross-linking with gelatin molecules increases, so that the cross-linking reaction is too early and the light control layer coating solution gels.

[formula]
OHC- _{(CH 2)} n -CHO general formula (1)

  Therefore, the progress of the crosslinking reaction by heating above the freezing point in the coating process is slow, and the viscosity of the light control layer coating solution is not significantly increased even if heating is performed for a long time. Is preferred.

  In the present embodiment, the crosslinking agent is preferably contained in an amount of 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 10% by mass or less, with respect to the nonvolatile component in the light control layer coating solution. More preferably. If the content of the crosslinking agent is less than 0.1% by mass, a sufficient crosslinking effect cannot be obtained, and if it exceeds 20% by mass, the viscosity of the light control layer coating solution is remarkably increased.

(Drying process)
Finally, the liquid absorbed in the gelatin in the coating layer is volatilized at a temperature below the freezing point of the gelatin while the coating layer formed on the display surface substrate in the second coating step is maintained in a gel state. Let dry.

  Here, since gelatin is a heat-denatured product of collagen, the molecular structure of gelatin in the sol state is a random coil shape, but gelatin in the gel state has a part of the molecule's original collagen helical structure. Network is formed. Therefore, the volumetric shrinkage of gelatin accompanying the volatilization of the liquid in the coating layer is larger when the drying process is performed in the gel state than in the sol state. The liquid crystal drops or liquid crystal microcapsules that are densely arranged in the holding step have a compressive force in the thickness direction and a tensile force in the plane direction compared to drying in the sol state by bringing the drying step into a gel state. Therefore, the liquid crystal drops or the liquid crystal microcapsules are each polyhedral.

  Each of the above steps (first coating step, crosslinking drying step, second coating step, and drying step) is performed by applying a light control layer coating solution in which a liquid crystal drop is dispersed in a solution containing gelatin, a crosslinking agent, and a solvent. The case where an application part is hold | maintained in the container of the volume as small as possible using FIG. 2 is demonstrated using FIG.

  FIG. 2A is a conceptual diagram showing the first coating process. In the first coating step, as shown in FIG. 2A, a light control layer coating solution in which a liquid crystal drop 32 is dispersed in a solution 37 containing gelatin, a crosslinking agent, and a solvent on the display surface substrate 20. Is applied by a coating device 60 to form a coating layer 39 on the display surface substrate 20.

  Next, in the cross-linking drying step, as shown in FIGS. 2B and 2C, the coating layer 39 formed in the first coating step shown in FIG. The display surface substrate 20 is heated by a heating device (not shown) to heat the coating layer 39 to a temperature higher than the freezing point of gelatin. The atmosphere in the sealed container is close to the saturated vapor pressure due to the initial volatilization of the solvent in the coating layer 39. In this state, since the solvent does not volatilize rapidly from the coating layer 39, each liquid crystal drop 32 is not distorted by vigorous liquid flow. As the solvent evaporates, the thickness of the coating layer 39 decreases, and accordingly, the liquid crystal drops 32 are naturally arranged in a dense state while gradually changing the positional relationship with each other.

  In the cross-linking drying step, as shown in FIG. 2C, the coating layer 39 is in a state higher than the freezing point of gelatin shown in FIG. 2B and close to the saturated vapor pressure, that is, in a high temperature and high humidity state. The display surface substrate 20 is continuously heated to a temperature higher than the freezing point of gelatin, whereby the gelatin contained in the coating layer 39 is crosslinked by the crosslinking agent contained in the coating layer 39. When the solvent is completely volatilized, a flat coating layer 39 with few irregularities in which the liquid crystal drops 32 are densely arranged is obtained. 2B and 2C, a coating layer in which gelatin is crosslinked with a crosslinking agent and gelatin is in a sol state (crosslinked sol state) is obtained.

  Next, in the second coating step, as shown in FIG. 2D, the display surface substrate 20 on which the coating layer 39 in which the gelatin is in a crosslinked sol state is formed by the crosslinking drying step is removed from the sealed container 70. The liquid 41 for changing the gelatin in the coating layer to the sol-gel is coated on the coating layer 39 by the coating device 62. This second coating step is performed in an environment where the coating layer 39 is at a temperature below the freezing point of gelatin. By this second coating step, the gelatin in the coating layer 39 absorbs the applied liquid and swells, and the coating layer 39 is placed at a temperature below the freezing point of the gelatin, so that the gelatin in the crosslinked sol state becomes It becomes a crosslinked gel state.

  Finally, in the drying step, as shown in FIG. 2 (E), the liquid applied to change the sol-gel of gelatin in the second coating step and absorbed in the gelatin in the coating layer 39 is Volatilize at a temperature below the freezing point of gelatin.

  In the second coating step, the gelatin swells in the liquid while being crosslinked by the crosslinking agent, and changes from the sol state to the gel state. Therefore, the density of the liquid crystal drop 32 contained in the coating layer 39 is increased. Gelates without breaking the state. Gelatin has a larger volume shrinkage of gelatin due to volatilization of the liquid in the coating layer when it is dried in the gel state than in the sol state. As the volume of the gelatin decreases, a compressive force acts in the thickness direction and a tensile force acts in the surface direction as the volume of the gelatin shrinks, and each liquid crystal drop 32 is flattened. At this time, since the liquid crystal drops 32 are in a dense state by the cross-linking and drying step, the liquid crystal drops are densely arranged as shown in FIG. It is polyhedral in the state.

  The gelatin material used in the first embodiment preferably has a low sol viscosity so as not to inhibit the movement of the liquid crystal drop or liquid crystal microcapsule, and the jelly that suppresses leakage of liquid crystal droplets on the light control layer surface after the drying step is completed. Those having high strength are preferred, and gelatin subjected to acid treatment using beef bone as a raw material is preferred from the above viewpoint.

The reason why the liquid crystal drop or liquid crystal microcapsule is polyhedral due to gelatin sol-gel change, which is a feature of the first embodiment, has not been clarified.
Since gelatin is a heat-denatured product of collagen, the molecular structure of gelatin dried in the sol state has a random coil shape. Gelatin dried in the gel state is part of the original collagen helix. A network is formed with a structure. It is considered that volume shrinkage occurs when gelatin changes from a sol state to a gel state. Therefore, if the coating layer is dried in the sol state without changing the sol-gel, the volumetric contraction of gelatin due to the volatilization of the liquid in the coating layer does not occur. Therefore, the liquid crystal drop or the liquid crystal microcapsule is flattened. It is considered difficult to make it multifaceted.

  In addition, in the light control layer prepared by preparing a light control layer coating solution so as not to contain a crosslinking agent, and applying and drying steps, when the liquid for changing the sol-gel is applied to the light control layer, gelatin Since the gelatin network in the light control layer is unwound due to the swelling of the liquid crystal, it becomes impossible to hold the liquid crystal drop or the liquid crystal microcapsule, and the liquid crystal drop or the liquid crystal microcapsule is coalesced. It is considered that the PDLC structure in which the capsules are densely arranged is broken.

  On the other hand, according to the first embodiment, a light control layer in which liquid crystal drops or liquid crystal microcapsules are dispersed in a solution containing gelatin, a crosslinking agent capable of crosslinking gelatin, and a solvent on the support substrate in the first coating step. In the crosslinking and drying step, the coating layer is dried at a temperature higher than the freezing point of the gelatin, and the gelatin in the coating layer is crosslinked with a crosslinking agent to thereby form the gelatin in the coating layer. In order to change the sol-gel, it is made into a crosslinked sol state, and after the liquid for changing the sol-gel of gelatin in the second coating step is applied, it is evaporated and dried at a temperature below the freezing point of gelatin in the drying step. Even if this liquid is applied, the liquid crystal drops or liquid crystal microcapsules are densely arranged without breaking the PDLC structure. Gelatin in the layer can be changed to a gel state, and as the liquid for changing the sol-gel is volatilized, a compressive force acts in the thickness direction and a tensile force acts in the surface direction. Drops or liquid crystal microcapsules can be flattened and finally polyhedral.

  Further, as described above, the method of forming the second light control layer on the non-display surface substrate is also performed in accordance with the above method.

<Second Embodiment>
Further, as another configuration of the light modulation element according to the present embodiment, the light modulation element according to the second embodiment can be mentioned. As a configuration of the light modulation element according to the second embodiment, at least one has a pair of light-transmitting substrates, and a first liquid crystal is contained in a region sandwiched between the pair of substrates. And a first light control layer, a second light control layer containing a second liquid crystal having a threshold larger than that of the first liquid crystal, and an electrode layer, and the first and second layers from the electrode layer. A configuration having a control unit that controls the magnitude of the applied voltage applied to the light control layer is raised.
The “threshold value” refers to the lowest stimulation amount that causes a reaction, that is, the lowest applied voltage that increases (changes) the domain size.

  The domain of the first liquid crystal is adjusted so that the applied voltage applied from the electrode layer to the first dimming layer and the second dimming layer does not change the domain size of the second liquid crystal. By controlling to change the size, only the domain size of the liquid crystal contained in the first light control layer is controlled, and as a result, the width of the viewing angle can be adjusted.

[Experimental example]
Hereinafter, a specific example of the liquid crystal display element which is the light modulation element according to the first embodiment will be shown, and the effect thereof will be verified.

-Preparation of liquid crystal material-
As a liquid crystal material for forming the first dimming layer 30A and the second dimming layer 30B shown in FIG. 1, a cholesteric liquid crystal that selectively reflects green color light having a wavelength of 550 nm is prepared by mixing a nematic liquid crystal with a chiral agent. did. At that time, a liquid crystal material having a resistance value three times that of the liquid crystal material used for the second light control layer 30B was selected as the liquid crystal material used for the first light control layer 30A.

-Production of liquid crystal display elements-
An ITO electrode film having a thickness of 20 nm was formed on a glass substrate as the display surface substrate 21 to form a first electrode layer 22. Next, on the ITO electrode film of the glass substrate as the display surface substrate 21, the liquid crystal for the first light control layer 30A was formed with a thickness of 5 μm, and spherical spacer beads of 5 μm were further dispersed. On the liquid crystal layer, a polyethylene terephthalate film having a thickness of 2 μm was adhered as the intermediate layer 50 so as to adhere to the spacer beads.

  On the other hand, an ITO electrode film having a thickness of 20 nm was formed on a glass substrate as the non-display surface substrate 11 to form a second electrode layer 12. Next, the liquid crystal for the second light control layer 30B was formed to a thickness of 5 μm on the ITO electrode film of the glass substrate as the non-display surface substrate 11, and spherical spacer beads of 5 μm were further dispersed.

Next, the surface on which the intermediate layer 50 of the glass substrate as the display surface substrate 21 is opposed to the surface on which the second light control layer 30B of the glass substrate as the non-display surface substrate 11 is formed. The light adjusting layer 30B was adhered so as to adhere to the spacer beads.
Furthermore, the light shielding layer was formed in the surface on the opposite side to the 2nd light control layer 30B formation surface of the glass substrate as the non-display surface board | substrate 11. FIG.
Thereafter, the spacer beads are heated to 110 ° C. to bring the ITO electrode film as the first electrode layer 22, the ITO electrode film as the second electrode layer 12, and the polyethylene terephthalate film as the intermediate layer 50 into close contact. For 30 minutes to obtain a liquid crystal display element.

-Evaluation-
FIG. 5 shows the domain size of the liquid crystal material of the first light control layer 30A when the magnitude of the applied voltage is changed. (A) is when the applied voltage is 200V, and (b) is when the applied voltage is 500V. In (a), a liquid crystal having a fine domain size can be seen, whereas in (b), it can be seen that the domain size is larger than that in (a).

  In addition, the measurement results of the reflection characteristics are shown in FIG. FIG. 6 shows the reflectance (%) measured while changing the viewing angle when the voltage applied to the first light control layer 30A is changed. FIG. 6 shows that when the applied voltage is low (100 V and 200 V), the reflectance peak is broad, that is, the viewing angle is widened. On the other hand, when the applied voltage is high (300 V and 500 V), it can be seen that the reflectance peak is sharp, that is, the viewing angle is narrow.

From the above results, the magnitude of the applied voltage applied from the first electrode layer 22 to the first dimming layer 30A and the second dimming layer 30B is determined based on the domain of the liquid crystal in the second dimming layer 30B. By controlling to change the liquid crystal domain size in the first light control layer 30A within a range where the size does not change, only the liquid crystal domain size contained in the first light control layer 30A can be changed. As a result, it was found that the viewing angle can be adjusted.
As can be seen from FIG. 6, the color purity in that case did not change significantly.

(A) is a schematic sectional drawing which shows the state which applied the applied voltage lower than (B) to the 1st light control layer of the light modulation element of 1st Embodiment, (B) is the light modulation of 1st Embodiment. It is a schematic sectional drawing which shows the state which applied the applied voltage higher than (A) to the 1st light control layer of an element. It is a schematic diagram which shows each process which manufactures the light control layer of the light modulation element of this embodiment, FIG. 2 (A) shows a 1st application | coating process, FIG. 2 (B) shows the middle of a bridge | crosslinking drying process. FIG. 2 (C) shows a state where the cross-linking and drying step is completed, FIG. 2 (D) shows a second coating step, and FIG. 2 (E) is a schematic diagram showing the drying step. It is a schematic diagram which shows the arrangement | sequence state of a cholesteric liquid crystal, (A) shows a planar state, (B) shows a focal conic state, (C) is a schematic diagram which shows a homeotropic state. It is a graph which shows the electro-optic response of the cholesteric liquid crystal which has positive dielectric anisotropy. It is an enlarged view which shows the mode of the domain size of the liquid-crystal material of a 1st light control layer when the magnitude | size of an applied voltage is changed. It is the graph which showed the reflectance (%) according to a viewing angle in the case of changing the applied voltage to the 1st light control layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light modulation element 11, 21 Substrate 12, 22 Electrode 30A, 30B Light control layer 32 Liquid crystal drop 34 Gelatin 36 Liquid crystal microcapsule 37 Solution 39 Coating layer

Claims (4)

At least one has a pair of translucent substrates,
And it has the 1st light control layer and the 2nd light control layer containing a liquid crystal, and the electrode layer which applies a voltage to at least the 1st light control layer in the field between the pair of substrates. With
A light modulation element having a control unit for controlling a height of an applied voltage applied from the electrode layer to the first light control layer. At least one has a pair of translucent substrates,
In a region sandwiched between the pair of substrates, the first electrode layer, the first light control layer, the intermediate layer, the second light control layer, and the second electrode layer are provided. Have in order,
The light modulation element according to claim 1, further comprising a control unit that controls a height of an applied voltage applied from the first electrode layer to the first light control layer. At least one has a pair of light-transmitting substrates, and a first light control layer and a second light control layer containing liquid crystal in a region sandwiched between the pair of substrates, and at least the first light control layer An electrode layer for applying a voltage to the light control layer,
A method for driving a light modulation element, wherein a domain size of a liquid crystal contained in the first light control layer is controlled by adjusting a height of an applied voltage applied from the electrode layer to the first light control layer. At least one has a pair of light-transmitting substrates, and a region sandwiched between the pair of substrates includes a first electrode layer, the first light control layer, an intermediate layer, and the second layer. For the light modulation element having the light control layer and the second electrode layer in this order,
4. The domain size of the liquid crystal contained in the first light control layer is controlled by adjusting a height of an applied voltage applied from the first electrode layer to the first light control layer. 5. Driving method of the light modulation element.