JP7395952B2 - Light control sheet and light control device - Google Patents

Description

The present invention relates to a light control sheet including a transparent electrode layer and a light control device.

The light control sheet includes a liquid crystal composition sandwiched between a first transparent electrode layer and a second transparent electrode layer. When a voltage is applied between the first transparent electrode layer and the second transparent electrode layer, the liquid crystal composition changes the alignment state of the liquid crystal molecules and changes from transparent to opaque or from opaque to transparent. Light control sheets are classified into normal type and reverse type. A normal type light control sheet changes from opaque to transparent when energized, and a reverse type light control sheet changes from transparent to opaque when energized (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2000-321562

In recent years, the scope of applications for light control sheets has been expanding to include building entrances and large screens, and a new challenge has arisen: increasing the uniformity of transmittance within the surface of light control sheets.

An object of the present invention is to provide a light control sheet and a light control device that can improve the uniformity of transmittance within the plane of the light control sheet.

A light control sheet for solving the above problems includes a first transparent electrode layer having a first terminal, a second transparent electrode layer having a second terminal, the first transparent electrode layer and the second transparent electrode layer. The liquid crystal layer includes a transparent polymer resin layer located between the liquid crystal layers and defining a plurality of voids, and a liquid crystal composition that fills the voids. The first terminal and the second terminal are located at both ends of the light control sheet in the longitudinal direction, and the voltage applied between the first terminal and the second terminal is a driving voltage Vin. The threshold voltage Von is the voltage threshold at which the light control sheet per unit area changes from opaque to transparent or from transparent to opaque by applying the voltage. The shortest distance between the first terminal and the second terminal is the inter-terminal distance L (m). The surface resistivities Rs (Ω/sq) of the first transparent electrode layer and the second transparent electrode layer satisfy equation (1).

Rs≦(-A×Vt+B)×L ^-C ... Formula (1)
Note that in equation (1), Vt=Von/Vin, A=1.5×10 ³ , B=1.5×10 ³ , and C=1.9.

According to a circuit simulation conducted by the present inventor, a voltage drop occurs between the first transparent electrode layer and the second transparent electrode layer at a position away from the first terminal and the second terminal. A partial voltage drop within the plane of the light control sheet reduces the uniformity of transmittance within the plane of the light control sheet. In this regard, according to the above configuration, since the surface resistivity Rs of each transparent electrode layer is a value that satisfies the above formula, even if a voltage drop occurs between the transparent electrode layers, the voltage applied between the transparent electrode layers is equal to or higher than the threshold voltage Von throughout the long axis direction of the light control sheet. As a result, the uniformity of transmittance within the plane of the light control sheet increases.

In the light control sheet, the capacitance value of the liquid crystal layer is 5×10 ⁻² (μF) or more and 1×10 ⁻¹ (μF) or less, and the resistance value of the liquid crystal layer is 0.5 M (Ω/sq ) or more and 1.5 M (Ω/sq) or less. According to this configuration, the effectiveness of achieving the effect of increasing the uniformity of transmittance within the plane of the light control sheet is increased.

In the light control sheet, the drive voltage Vin may be 50 (V) or less. According to this configuration, since the voltage used to drive the light control sheet is below the extra low voltage, the safety in driving the light control sheet is increased.

In the light control sheet, the drive voltage Vin may be 42 (V) or less. According to this configuration, since the voltage used to drive the light control sheet is below the safe extra low voltage, the safety in driving the light control sheet is further improved.

A light control device for solving the above problems includes a first transparent electrode layer having a first terminal, a second transparent electrode layer having a second terminal, and the first transparent electrode layer and the second transparent electrode layer. a liquid crystal layer located between the first terminal and the second terminal, the liquid crystal layer including a polymer transparent resin layer that partitions a plurality of voids, and a liquid crystal composition that fills the voids; and a drive unit that applies a voltage between them. The first terminal and the second terminal are located at both ends of the light control sheet in the longitudinal direction. The threshold voltage Von is the voltage threshold at which the light control sheet per unit area changes from opaque to transparent or from transparent to opaque by applying the voltage. The shortest distance between the first terminal and the second terminal is the inter-terminal distance L (m). The resistance value per unit area of the first transparent electrode layer and the second transparent electrode layer is the surface resistivity Rs (Ω/sq). The driving section may apply a driving voltage Vin as the voltage so as to satisfy the above equation.

According to the above configuration, since the surface resistivity of each transparent electrode layer satisfies the above formula, even if a voltage drop occurs between the transparent electrode layers, there is a difference between the first transparent electrode layer and the second transparent electrode layer. The applied voltage is equal to or higher than the threshold voltage Von throughout the light control sheet in the long axis direction. As a result, the uniformity of transmittance within the plane of the light control sheet increases.

In the light control device, the distance between the terminals is 1.8 (m) or less, the drive voltage Vin is 50 (V) or less, the threshold voltage Von is 40 (V) or less, and the surface resistance The ratio may be 120 (Ω/sq) or less.

According to the above light control device, since the surface resistivity is 120 (Ω/sq) or less, a voltage of 40 (V) or more, which is the threshold voltage Von, is applied to the transparent electrode even though the drive voltage Vin is below the special low voltage. Can be applied to the entire area between layers. Therefore, in a light control sheet in which the distance between terminals is 1.8 (m) or less, the effectiveness of increasing the uniformity of transmittance within the plane of the light control sheet is increased.

In the light control device, the distance between the terminals is 4.0 (m) or less, the drive voltage Vin is 50 (V) or less, the threshold voltage Von is 40 (V) or less, and the surface resistance The ratio may be 30 (Ω/sq) or less.

According to the above light control device, since the surface resistivity is 30 (Ω/sq) or less, a voltage of 40 (V) or more, which is the threshold voltage Von, is applied to the transparent electrode even though the drive voltage Vin is below the special low voltage. Can be applied to the entire area between layers. Therefore, in a light control sheet in which the distance between terminals is 4.0 (m) or less, the effectiveness of increasing the uniformity of transmittance within the plane of the light control sheet is increased.

A light control device for solving the above problems includes a first transparent electrode layer having a first terminal, a second transparent electrode layer having a second terminal, and the first transparent electrode layer and the second transparent electrode layer. a liquid crystal layer located between the first terminal and the second terminal, the liquid crystal layer including a polymer transparent resin layer that partitions a plurality of voids, and a liquid crystal composition that fills the voids; and a drive unit that applies a voltage between them. The first terminal and the second terminal are located at both ends of the light control sheet in the longitudinal direction. The threshold voltage Von is the voltage threshold at which the light control sheet per unit area changes from opaque to transparent or from transparent to opaque by applying the voltage. The shortest distance between the first terminal and the second terminal is the inter-terminal distance L (m). The resistance value per unit area of the first transparent electrode layer and the second transparent electrode layer is the surface resistivity Rs (Ω/sq). When applying the drive voltage Vin as the voltage, the drive unit increases the drive voltage Vin as the inter-terminal distance L input to the drive unit increases, and increases the drive voltage Vin to the threshold value input to the drive unit. The higher the voltage Von is, the higher the drive voltage Vin is.

As described above, a voltage drop occurs between the transparent electrode layers at a position away from the first terminal and the second terminal. At this time, the greater the distance L between the terminals, the greater the voltage drop between the transparent electrode layers. Furthermore, the higher the threshold voltage Von, the less likely the transmittance will change due to voltage drop. In this regard, according to the above configuration, the larger the distance L between the terminals inputted to the driving section, the higher the driving voltage Vin is increased, and the higher the threshold voltage Von inputted to the driving section, the higher the driving voltage Vin is increased. Therefore, even if a voltage drop occurs between the transparent electrode layers, the voltage applied between the transparent electrode layers is likely to be equal to or higher than the threshold voltage Von throughout the long axis direction of the light control sheet. As a result, the uniformity of transmittance within the plane of the light control sheet increases.

A cross-sectional view showing an example of a cross-sectional structure of a normal type light control sheet. FIG. 3 is a cross-sectional view showing an example of the cross-sectional structure of a reverse type light control sheet. FIG. 3 is a front view showing a light control sheet having unit areas. Graph showing the relationship between peak-to-peak value and haze value in a unit area. FIG. 3 is a plan view showing a light control sheet used for circuit simulation. Equivalent circuit diagram of a light control sheet used for circuit simulation. A graph showing the waveform of an AC voltage used in circuit simulation. A graph showing voltage waveforms of each transparent electrode layer in a unit area. Graph showing the distribution of interelectrode voltage in each unit area. A graph showing the relationship between terminal distance and threshold resistivity for each drive voltage.

Hereinafter, a light control sheet and a light control device will be described with reference to FIGS. 1 to 10.
The light control sheet is attached to a window of a moving object such as a vehicle or an aircraft, for example. Further, the light control sheet can be attached to, for example, windows of various buildings such as residences, stations, and airports, partitions installed in offices, show windows installed in stores, and entrances of buildings. Further, the light control sheet is used for a screen on which images are projected. The shape of the light control sheet may be planar or curved. The shape of the light control sheet may be a shape that follows the shape of the object to which the light control sheet is attached, or may be a shape different from the object to which the light control sheet is attached. The type of light control sheet may be a normal type or a reverse type.

First, with reference to FIGS. 1 and 2, a configuration example of a light control device including a normal type and a reverse type light control sheet will be described. Next, with reference to FIGS. 3 and 4, the threshold voltage Von when the light control sheet changes from opaque to transparent by voltage application will be described.

Next, conditions used for circuit simulation will be explained with reference to FIGS. 5 to 7. Then, with reference to FIGS. 8 to 10, the surface resistivity of the transparent electrode layer included in the light control sheet will be explained together with the results obtained from the circuit simulation.

[Normal type]
As shown in FIG. 1, one example of a light control device includes a normal light control sheet 10N and a drive unit 30. The normal light control sheet 10N includes a liquid crystal layer 11, a pair of transparent electrode layers 12, a pair of transparent support layers 13, and a pair of terminals 20.

The liquid crystal layer 11 includes a polymer transparent resin layer that defines a plurality of voids, and a liquid crystal composition that fills the voids. The type in which the liquid crystal layer 11 holds the liquid crystal composition is one selected from the group consisting of a polymer network type, a polymer dispersion type, and a capsule type.

The polymer network type includes a polymer transparent resin layer having a three-dimensional network shape. The transparent polymer resin layer holds the liquid crystal composition in interconnected mesh-like voids. The polymer dispersed type has a transparent polymer resin layer that defines a large number of isolated voids, and the liquid crystal composition is held in the voids dispersed in the transparent polymer resin layer. In the capsule type, a liquid crystal composition having a capsule shape is held in a transparent polymer resin layer.

The material forming the transparent polymer resin layer is, for example, an ultraviolet curable resin that is cured by irradiation with ultraviolet rays. The liquid crystal layer 11 may include a spacer in order to maintain the thickness of the liquid crystal layer 11 and to suppress variations in the thickness of the liquid crystal layer 11 within the plane of the normal light control sheet 10N. The spacer is, for example, a granular spacer. Particulate spacers include spherical spacers and non-spherical spacers. Non-spherical spacers include rectangular spacers, cross-shaped spacers, and rod-shaped spacers.

The liquid crystal composition includes, for example, any one of liquid crystal molecules constituting a nematic liquid crystal, liquid crystal molecules constituting a smectic liquid crystal, and liquid crystal molecules constituting a cholestic liquid crystal. The liquid crystal molecules have, for example, positive dielectric anisotropy, and the dielectric constant in the long axis direction of the liquid crystal molecules is larger than the dielectric constant in the short axis direction of the liquid crystal molecules. Examples of the liquid crystal molecules include Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoic acid ester-based, tolan-based, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, and dioxane-based liquid crystal molecules. be. The liquid crystal composition can also contain dichroic dyes, ultraviolet absorbers, and the like as components other than liquid crystal molecules.

The pair of transparent electrode layers 12 includes a first transparent electrode layer 12A and a second transparent electrode layer 12B. The first transparent electrode layer 12A and the second transparent electrode layer 12B sandwich the liquid crystal layer 11 in the thickness direction of the liquid crystal layer 11. The liquid crystal layer 11 is located between the first transparent electrode layer 12A and the second transparent electrode layer 12B.

Each transparent electrode layer 12 is colorless and transparent or colored and transparent, and transmits light in the visible light range. The material constituting each transparent electrode layer 12 is, for example, any material selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, and poly(3,4-ethylenedioxythiophene). It is one of a kind.

The surface resistivity Rs (Ω/sq) of each transparent electrode layer 12 is the electrical resistivity per unit area of 0.1 (m)×0.1 (m). The surface resistivity Rs is sheet resistance or sheet resistivity. The surface resistivity Rs of each transparent electrode layer 12 decreases as the thickness of the transparent electrode layer 12 increases.

The pair of transparent support layers 13 includes a first transparent support layer 13A and a second transparent support layer 13B. The first transparent support layer 13A and the second transparent support layer 13B sandwich the pair of transparent electrode layers 12 in the thickness direction of the liquid crystal layer 11. A pair of transparent electrode layers 12 are located between the first transparent support layer 13A and the second transparent support layer 13B. Each transparent support layer 13 is colorless and transparent or colored and transparent, and transmits light in the visible light range.

Each transparent support layer 13 is, for example, one selected from the group consisting of polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, and triacetyl cellulose. .

The pair of terminals 20 includes a first terminal 20A and a second terminal 20B. The first terminal 20A and the second terminal 20B are connected to separate transparent electrode layers 12. The first terminal 20A is connected to the first transparent electrode layer 12A over the entire width direction. The second terminal 20B is connected to the second transparent electrode layer 12B throughout the width direction. The first terminal 20A and the second terminal 20B are located at both ends of the light control sheet 10N in the longitudinal direction DL.

The tip of the first transparent electrode layer 12A in the long axis direction DL is exposed from the second transparent electrode layer 12B and the second transparent support layer 13B. The first terminal 20A is electrically connected to the tip of the first transparent electrode layer 12A in the long axis direction DL and the drive section 30. The base end portion of the second transparent electrode layer 12B in the long axis direction DL is exposed from the first transparent electrode layer 12A and the first transparent support layer 13A. The second terminal 20B is electrically connected to the base end portion of the second transparent electrode layer 12B in the long axis direction DL and the drive unit 30.

The shortest distance between the first terminal 20A and the second terminal 20B in the long axis direction DL is the inter-terminal distance L (m). When the light control sheet 10N has a rectangular sheet shape, the length in the width direction of the light control sheet 10N is the sheet width W (m).

Each terminal 20 is, for example, a laminate in which a conductive paste, a conductive tape, and a solder portion are laminated in this order on the transparent electrode layer 12. The conductive paste constituting each terminal 20 is connected to the transparent electrode layer 12. A solder portion forming each terminal 20 is connected to a drive section 30. Further, each terminal 20 is a laminate in which, for example, a conductive paste and a conductive adhesive layer such as a metal tape or a conductive film are laminated on the transparent electrode layer 12 in this order. The conductive adhesive layer constituting each terminal 20 is electrically connected to the drive unit 30 through a wiring board such as a flexible board.

The drive unit 30 is connected to the first terminal 20A and the second terminal 20B. The drive unit 30 applies an AC voltage between the first terminal 20A and the second terminal 20B. The waveform of the AC voltage is, for example, one selected from the group consisting of a sine wave, a square wave, and a triangular wave. The drive voltage Vin is the peak-to-peak value of the AC voltage applied between the first terminal 20A and the second terminal 20B. The driving voltage Vin is, for example, 40 (V) or more and 160 (V) or less. The drive frequency f is the frequency of the AC voltage applied between the first terminal 20A and the second terminal 20B. The driving frequency f is, for example, 30 (Hz) or more and 200 (Hz) or less.

When the driving voltage Vin is not applied between the first terminal 20A and the second terminal 20B, the polarization directions of the liquid crystal molecules are irregularly arranged, and the normal light control sheet 10N is in an opaque state. The liquid crystal layer 11 switches between a transparent state and an opaque state based on changes in the orientation of liquid crystal molecules. The drive unit 30 applies an AC voltage between the first terminal 20A and the second terminal 20B to change the orientation of the liquid crystal molecules so that the normal light control sheet 10N changes from an opaque state to a transparent state.

[Reverse type]
As shown in FIG. 2, another example of the light control device includes a reverse type light control sheet 10R and a drive unit 30. The reverse type light control sheet 10R includes a liquid crystal layer 11, a pair of transparent electrode layers 12, a pair of transparent support layers 13, and a pair of terminals 20, as well as a pair of alignment layers 14.

One of the alignment layers 14 is composed of a first alignment layer 14A and a second alignment layer 14B. The first alignment layer 14A and the second alignment layer 14B sandwich the liquid crystal layer 11 in the thickness direction of the liquid crystal layer 11. The first alignment layer 14A is located between the liquid crystal layer 11 and the first transparent electrode layer 12A, and applies alignment regulating force to liquid crystal molecules. The second alignment layer 14B is located between the liquid crystal layer 11 and the second transparent electrode layer 12B, and applies alignment regulating force to liquid crystal molecules.

The alignment layer 14 is, for example, a transparent vertical alignment film. The material constituting the alignment layer 14 may be, for example, polyamide, polyimide, polycarbonate, polystyrene, polysiloxane, polyester, polyacrylate, or the like. Polyesters include, for example, polyethylene terephthalate and polyethylene naphthalate. Polyacrylate is, for example, polymethyl methacrylate. Note that for the alignment treatment for forming the alignment layer 14, it is also possible to use, for example, rubbing treatment, polarized light irradiation treatment, microfabrication treatment, and the like.

When the pair of alignment layers 14 are vertical alignment films, when the application of the AC voltage between the first terminal 20A and the second terminal 20B is stopped, the polarization direction of the liquid crystal molecules is aligned vertically. The light incident on the light control sheet 10R is transmitted through the liquid crystal layer 11 without being substantially scattered in the liquid crystal layer 11. As a result, the reverse type light control sheet 10R becomes transparent when no AC voltage is applied between the first terminal 20A and the second terminal 20B.

When the pair of alignment layers 14 are vertical alignment layers, when the driving voltage Vin is applied between the first terminal 20A and the second terminal 20B, the polarization direction of the liquid crystal molecules changes from vertical alignment to horizontal alignment, for example. change. Then, the light incident on the light control sheet 10R is scattered by the liquid crystal layer 11. As a result, the reverse type liquid crystal layer 11 becomes opaque when an AC voltage is applied between the first terminal 20A and the second terminal 20B.

Note that when each of the reverse type and normal type light control sheets has a rectangular sheet shape, the direction along the long side of the light control sheet is the long axis direction DL, and the long axis direction DL within the surface of the light control sheet. The direction perpendicular to the axial direction DL is the width direction. Note that when the light control sheet has an elliptical sheet shape, the direction along the long axis of the light control sheet is the long axis direction DL, and the direction along the short axis within the surface of the light control sheet is the short axis direction. When the light control sheet has a circular sheet shape, the direction along the diameter of the light control sheet is the major axis direction DL. That is, the long axis direction DL of the light control sheet is the direction in which a straight line passing through the center of the liquid crystal layer 11 extends when viewed from a position facing the liquid crystal layer 11, and the straight line intersects with the edge of the light control sheet. This is the direction in which the distance between two points is greater than or equal to all other straight lines.

Further, in each of the reverse type and normal type light control sheets, the transparent light control sheet allows the outline of the observation target to be visually recognized through the light control sheet. The opaque light control sheet makes it impossible to visually recognize the outline of the observation target through the light control sheet. The haze value of the opaque light control sheet according to JIS K 7136:2000 is, for example, 95% or more. The haze value of the transparent light control sheet according to JIS K 7136:2000 is, for example, 50% or less.

Further, each of the reverse type and normal type light control sheets may further include a barrier layer between the liquid crystal layer 11 and the transparent electrode layer 12. Further, the light control sheet may further include a barrier layer that covers the end faces of the liquid crystal layer 11, the end faces of the transparent electrode layer 12, and the like. The barrier layer has at least one of a function of suppressing the transmission of water, oxygen, etc., and a function of suppressing the transmission of ultraviolet rays.

Each of the reverse type and normal type light control sheets further includes an undercoat layer between the liquid crystal layer 11 and the transparent electrode layer 12 or between the transparent electrode layer 12 and the transparent support layer 13. Good too. Further, the light control sheet may further include an undercoat layer that covers the end faces of the liquid crystal layer 11, the end faces of the transparent electrode layer 12, and the like. The undercoat layer has a function of improving the adhesion between the liquid crystal layer 11 and the transparent electrode layer 12, a function of improving the adhesion between the transparent electrode layer 12 and the transparent support layer 13, and an electrical connection between the transparent electrode layer 12 and the outside. It has functions such as protecting connections.

Further, each of the reverse type and normal type light control sheets may further include a light transmitting layer such as a hard coat layer or a transparent base material on the outside of the transparent support layer 13. The light transmitting layer has a function of increasing the mechanical strength of the light control sheet. Further, the light control sheet may further include a light transmitting layer between the liquid crystal layer 11 and the transparent electrode layer 12 or between the transparent electrode layer 12 and the transparent support layer 13.

Examples of materials that make up the light-transmitting layer include transparent inorganic materials such as glass and silicon, transparent organic materials such as polymethacrylate resin, polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, and polysulfone. It is.

[Surface resistivity]
The surface resistivity Rs (Ω/sq) of the transparent electrode layer 12 included in each of the light control sheets 10N and 10R satisfies the following formula (1), which is a relational expression between the voltage ratio Vt and the inter-terminal distance L. Constants A, B, and C in equation (1) are shown below. The voltage ratio Vt in equation (1) is the ratio of the drive voltage Vin to the threshold voltage Von.
Rs≦(-A×Vt+B)×L ^-C ... Formula (1)
A=1.5×10 ³ , B=1.5×10 ³ , C=1.9
Vt=Von/Vin

[Threshold voltage Von]
Next, with reference to FIG. 3 and FIG. 4, the relationship between the peak-to-peak value of the AC voltage applied between the first transparent electrode layer 12A and the second transparent electrode layer 12B and the haze value, and The threshold voltage Von will be explained. In FIG. 3, dark dots are added to regions where the first transparent electrode layer 12A and the second transparent electrode layer 12B overlap when viewed from a viewpoint facing the second transparent support layer 13B. The area marked with dark dots is the unit area N for specifying the threshold voltage Von. In addition, in FIG. 3, thin dots are attached to regions where only the second transparent electrode layer 12B is located.

The threshold voltage Von is the threshold of the peak-to-peak value when the entire normal type light control sheet 10N in the unit area N changes from opaque to transparent by application of an AC voltage, that is, when the haze value stops changing from opaque to transparent. It is. The threshold voltage Von is the threshold of the peak-to-peak value when the entire reverse type light control sheet 10R in the unit area N changes from transparent to opaque by application of an AC voltage, that is, when the haze value changes from transparent to opaque and the haze value does not change. It is.

The unit area N for specifying the threshold voltage Von is also the size of the minimum unit for specifying the surface resistivity Rs. The dimensions in the unit area N for specifying the threshold voltage Von and the AC voltage applied to the light control sheet 10 are shown below.
・Distance between terminals L: 0.1 (m)
・Seat width W: 0.1 (m)
・Terminal width LD: 5 (mm)
・AC voltage waveform: sine wave ・Drive frequency f: 50 (Hz)

The liquid crystal resistance R1, which is the resistance value between the transparent electrode layers 12A and 12B in the unit area N, and the liquid crystal capacitance C1, which is the capacitance value between the transparent electrode layers in the unit area N, are shown below. Further, the terminal width LD, which is the size in the width direction to which each terminal 20A, 20B is connected, and the contact resistance between each terminal 20A, 20B and the transparent electrode layer 12 are shown below.
・Liquid crystal resistance R1: 1M (Ω/sq)
・Liquid crystal capacitance C1: 8×10 ^-2 (μF)
・Contact resistance value: 1 (Ω/sq) or more and 10 (Ω/sq) or less

FIG. 4 shows the results of haze value measurement performed to specify the threshold voltage Von. The relationship between the peak-to-peak value and the haze value will be shown using the normal type light control sheet 10N as an example. Note that the haze value in the normal type light control sheet 10N is lower as the peak-to-peak value is higher, while the haze value in the reverse type light control sheet 10R is higher as the peak-to-peak value is higher. The specification of the threshold voltage Von in the normal type light control sheet 10N and the specification of the threshold voltage Von in the reverse type light control sheet 10R differ in whether the haze value decreases or increases due to the application of an AC voltage. They are common in other respects. Below, an example will be shown in which the threshold voltage Von is specified in the normal type light control sheet 10N, and a redundant explanation will be omitted regarding an example in which the threshold voltage Von is specified in the reverse type light control sheet 10R.

As shown in FIG. 4, when the peak-to-peak value of the AC voltage applied between the first terminal 20A and the second terminal 20B is in the range from 0 (V) to 10 (V), the haze in the light control sheet 10 The value is saturated at approximately 100 (%). When the peak-to-peak value of the AC voltage applied between the first terminal 20A and the second terminal 20B changes from 10 (V) to 40 (V), the haze value in the light control sheet 10 sharply changes from 100 (%). and reaches 10(%). In a range where the peak-to-peak value of the AC voltage applied between the first terminal 20A and the second terminal 20B exceeds 40 (V), the haze value in the light control sheet 10 is saturated at 10 (%).

At this time, the threshold value of the peak-to-peak value when the normal type light control sheet 10N changes from opaque to transparent by the application of voltage is the lowest peak-to-peak value when the haze value of the light control sheet 10N is saturated at 10 (%). It is. That is, the threshold voltage Von is 40 (V).

[Relational expression]
Next, with reference to FIGS. 5 to 10, the derivation of the above relational expression, which is a relational expression using the voltage ratio Vt and the inter-terminal distance L, will be described. The relational expression between the voltage ratio Vt and the inter-terminal distance L is derived by applying the equivalent circuit of the light control sheet to circuit simulation. The circuit simulation of the light control sheet is performed within a range that satisfies the following sheet conditions, element conditions, and power supply conditions.

First, with reference to FIGS. 5 and 6, an equivalent circuit applied to circuit simulation will be described together with sheet conditions and element conditions. Next, with reference to FIGS. 7 and 8, the AC voltage applied to the circuit simulation will be explained together with the power supply conditions. Next, an example of the results of the circuit simulation and the surface resistivity Rs of each transparent electrode layer 12A, 12B will be described with reference to FIGS. 9 and 10.

FIG. 5 shows an example of a light control sheet applied to circuit simulation. In FIG. 5, dark dots are added to regions where the first transparent electrode layer 12A and the second transparent electrode layer 12B overlap when viewed from a viewpoint facing the second transparent support layer 13B. The region marked with dark dots includes a plurality of unit regions N in the long axis direction DL and in the width direction. In addition, in FIG. 5, thin dots are attached to regions where only the second transparent electrode layer 12B is located.

The sheet width W and terminal width LD of the light control sheet applied to the circuit simulation satisfy the following sheet conditions. Note that the circuit simulation software is LTSPICE IV (manufactured by Linear Technology Corporation).

[Sheet conditions]
・Seat width W: 1.5 (m)
・Terminal width LD: 5 (mm)

FIG. 6 shows an equivalent circuit of the light control sheet applied to the circuit simulation.
As shown in FIG. 6, the equivalent circuit of the light control sheet is a set of equivalent circuits representing a unit area N. That is, the equivalent circuit in the liquid crystal layer 11 in the unit area N is approximated as a parallel circuit of the liquid crystal resistor R1 and the liquid crystal capacitor C1. Further, an equivalent circuit of a light control sheet having a plurality of unit areas N is a parallel circuit of unit areas N connected in parallel in the width direction by surface resistance R2 in the width direction, and a surface resistance R2 in the long axis direction DL. It is approximated as a set of equivalent circuits of unit regions N connected in parallel in the long axis direction DL.

The surface resistance R2 in the width direction of the first transparent electrode layer 12A is a resistance based on the surface resistivity Rs in the width direction of the unit electrode layer D1, which is the first transparent electrode layer 12A included in the unit region N. The surface resistance R2 in the width direction of the second transparent electrode layer 12B is a resistance based on the surface resistivity Rs in the width direction of the unit electrode layer D2, which is the second transparent electrode layer 12B included in the unit region N.

The surface resistance R3 in the long axis direction DL of the first transparent electrode layer 12A is also a resistance based on the surface resistivity Rs in the long axis direction DL of the unit electrode layer, which is the first transparent electrode layer 12A included in the unit area N. be. The surface resistance R3 in the long axis direction DL of the second transparent electrode layer 12B is also a resistance based on the surface resistivity Rs in the width direction of the unit electrode layer, which is the second transparent electrode layer 12B included in the unit area N.

The liquid crystal resistance R1, liquid crystal capacitance C1, and contact resistance of each terminal 20A, 20B of the light control sheet applied to the circuit simulation satisfy the following element conditions.
[Element conditions]
・Resistance value of liquid crystal layer: 1M (Ω/sq)
・Capacitance value of liquid crystal layer: 8×10 ^-2 (μF)
・Contact resistance value: 1 (Ω/sq) or more and 10 (Ω/sq) or less

The power supply voltage applied to circuit simulation satisfies the following power supply conditions. That is, as shown in FIG. 7, the AC voltage applied to the circuit simulation is a sine wave with a driving frequency f of 50 (Hz). The driving voltage Vin is 40 (V) or more and 160 (V) or less. In the example shown in FIG. 7, the drive voltage Vin is 140 (V). Then, a drive voltage Vin having a drive frequency of 50 (Hz) is applied to the equivalent circuit of the light control sheet.
[Power conditions]
・Power supply voltage waveform: Sine wave ・Drive frequency f: 50 (Hz)
- Driving voltage Vin: 40 (V) or more and 160 (V) or less In the circuit simulation of the light control sheet, the voltage applied to the liquid crystal capacitor C1 of the unit area N is calculated as the interelectrode voltage Vn for each unit area N. . The interelectrode voltage Vn is the peak value of the AC voltage applied between the first transparent electrode layer 12A and the second transparent electrode layer 12B in the unit area N.

FIG. 8 shows an example of the interelectrode voltage Vn in one unit region N. In FIG. 8, the first voltage VinA, which is the voltage of the first transparent electrode layer 12A in one unit area N, is shown by a solid line. The first voltage VinA is a voltage on the ground side of the light control sheet. Moreover, in FIG. 8, the second voltage VinB, which is the voltage of the second transparent electrode layer 12B in one unit area N, is indicated by a broken line. The second voltage VinB is the voltage on the power supply side of the light control sheet.

As shown in FIG. 8, the first voltage VinA has a peak-to-peak value of 0.5 (V) or less and approximately 0 (V). The second voltage VinB has a peak value of 70 (V) and has a waveform that is advanced by 90° from the power supply voltage. The interelectrode voltage Vn in one unit region N is the peak value of the difference between the first voltage VinA and the second voltage VinB in the unit region N.

In the circuit simulation of the light control sheet, one unit region N in which the inter-electrode voltage Vn has a minimum value is calculated from among all the unit regions N for each pair of inter-terminal distance L and drive voltage Vin. The distance L between the terminals is between 1.8 (m) and 4.0 (m), and is changed from 1.8 (m) by 0.2 (m), for example. The driving voltage Vin is 40 (V) or more and 160 (V) or less, and is increased by 2 (V) from 40 (V), for example.

For example, in a circuit simulation, the inter-electrode voltage Vn of a set in which the distance L between the terminals is 1.8 (m) and the drive voltage Vin is 42 (V) is a unit area located at the center of the long axis direction DL. Calculate the minimum value of N. In addition, in the circuit simulation, the inter-electrode voltage Vn of a set in which the inter-terminal distance L is 2.0 (m) and the drive voltage Vin is 42 (V) is a unit area located at the center of the long axis direction DL. Calculate that N is the minimum.

In the circuit simulation, one interelectrode voltage Vn is calculated for each surface resistivity Rs for a unit area N in which the interelectrode voltage Vn has a minimum value. That is, in the circuit simulation, one inter-electrode voltage Vn is calculated for one set of inter-terminal distance L, drive voltage Vin, and surface resistivity Rs. The surface resistivity Rs is between 1 (Ω/sq) and 250 (Ω/sq), and is, for example, a value that increases by 10 (Ω/sq) from 1 (Ω/sq).

For example, in a circuit simulation, for one set in which the distance L between terminals is 1.8 (m) and the driving voltage Vin is 42 (V), electrodes in a unit area N located at the center of the long axis direction DL are The voltage Vn is calculated using each surface resistivity Rs from 1 (Ω/sq) to 250 (Ω/sq). In addition, the circuit simulation was performed using electrodes in a unit area N located at the center of the long axis direction DL for one set in which the distance L between terminals is 2.0 (m) and the drive voltage Vin is 42 (V). The voltage Vn is calculated using each surface resistivity Rs from 1 (Ω/sq) to 250 (Ω/sq).

In the circuit simulation, for each pair of inter-terminal distance L and drive voltage Vin, from among the inter-electrode voltages Vn using all the surface resistivities Rs, the surface resistance where the inter-electrode voltage Vn is more than half of the threshold voltage Von is calculated. Identify the rate Rs. Then, in the circuit simulation, the maximum value among the specified surface resistivities Rs is set as the threshold resistivity corresponding to the combination of the inter-terminal distance L and the drive voltage Vin.

For example, in a circuit simulation, for one set in which the distance L between the terminals is 1.8 (m) and the drive voltage is 42 (V), the surface resistivity is such that the interelectrode voltage Vn is more than half the threshold voltage Von. As Rs, 1 (Ω/sq) or more and 50 (Ω/sq) or less are specified. Then, the circuit simulation calculates that the threshold resistivity is 50 (Ω/sq) for a set in which the inter-terminal distance L is 1.8 (m) and the drive voltage is 42 (V). In addition, the circuit simulation shows that for one set in which the distance L between the terminals is 2.0 (m) and the driving voltage is 42 (V), the surface resistivity is such that the inter-electrode voltage Vn is more than half the threshold voltage Von. As Rs, a value of 1 (Ω/sq) or more and 40 (Ω/sq) or less is specified. Then, the circuit simulation calculates that the threshold resistivity is 40 (Ω/sq) for a set in which the inter-terminal distance L is 2.0 (m) and the drive voltage is 42 (V).

FIG. 9 shows an example of the distribution of the inter-electrode voltage Vn for each unit area N when the inter-terminal distance L, the driving voltage Vin, and the surface resistivity Rs satisfy the following conditions. FIG. 9 shows the interelectrode voltage Vn in the unit area N with respect to the distance from the first terminal 20A in the long axis direction DL and the distance from one end in the width direction.
・Distance between terminals L: 4.0 (m)
・Driving voltage Vin: 50 (V)
・Surface resistivity Rs: 200 (Ω/sq)

As shown in FIG. 9, the further away from the first terminal 20A and the further away from the second terminal 20B, the lower the interelectrode voltage Vn. The interelectrode voltage Vn gradually decreases toward the center position S, which is the center in the longitudinal direction DL between the first terminal 20A and the second terminal 20B. On the other hand, the interelectrode voltage Vn is approximately equal from one end to the other end in the width direction. That is, the minimum value among the interelectrode voltages Vn in all unit areas N is the interelectrode voltage Vn at the center position S.

In this way, the tendency that the inter-electrode voltage Vn at the central position S is the minimum value in all unit areas N is determined by the other inter-terminal distances L, other drive voltages Vin, and other surface resistances. The same applies to the rate Rs. In other words, if the light control sheet has a surface resistivity Rs such that the interelectrode voltage Vn at the center position S is equal to or higher than the threshold voltage Von, approximately equal transmittance can be obtained in each unit area N, that is, the light control sheet It can be said that the uniformity of transmittance can be improved within the plane.

FIG. 10 shows the maximum value of the surface resistivity Rs that satisfies that the minimum value of the inter-electrode voltage Vn is equal to or higher than the threshold voltage Von (=40 (V)), and shows the dependence of the inter-terminal distance L at the maximum value. It is a graph showing each drive voltage Vin. The maximum value of the surface resistivity Rs that satisfies that the minimum value of the inter-electrode voltage Vn is equal to or higher than the threshold voltage Von is the threshold resistivity described above. FIG. 10 shows an example of the threshold resistivity when the distance L between the terminals and the drive voltage Vin satisfy the following conditions.
・Distance between terminals L: 1.8 (m) or more and 4 (m) or less ・Drive voltage Vin: 42 (V) or more and 60 (V) or less

As shown by the dashed line in FIG. 10, the threshold resistivity is 50 (Ω/sq) when the drive voltage Vin is 42 (V) and the inter-terminal distance L is 1.8 (m). That is, if the surface resistivity Rs is 50 (Ω/sq) or less, the transmittance is saturated in all unit areas N of the light control sheet where the distance L between the terminals is 1.8 (m), and the light control is not possible. The entire surface of the sheet changes from opaque to transparent. Such threshold resistivity decreases as the distance L between the terminals increases. For example, when the drive voltage Vin is 42 (V) and the distance L between terminals is 4.0 (m), the threshold resistivity is 10 (Ω/sq).

As shown by the broken line in FIG. 10, the threshold resistivity is 120 (Ω/sq) when the drive voltage Vin is 50 (V) and the inter-terminal distance L is 1.8 (m). This threshold resistivity is higher than the threshold resistivity when the drive voltage Vin is 42 (V). In other words, if the surface resistivity Rs is 120 (Ω/sq) or less, the transmittance will be saturated in all unit areas N of the light control sheet where the distance L between the terminals is 1.8 (m), and the light control will not be possible. The entire surface of the sheet changes from opaque to transparent.

Note that the threshold resistivity when the drive voltage Vin is 50 (V) over the entire range of the distance L between terminals from 1.8 (m) to 4.0 (m) is when the drive voltage Vin is 42 (V). ). For example, when the drive voltage Vin is 50 (V) and the distance L between terminals is 4.0 (m), the threshold resistivity is 30 (Ω/sq).

Furthermore, when the drive voltage Vin is 50 (V), the degree of decrease in the threshold resistivity with respect to an increase in the inter-terminal distance L is greater than when the drive voltage Vin is 42 (V).
As shown by the solid line in FIG. 10, the threshold resistivity is 180 (Ω/sq) when the drive voltage Vin is 60 (V) and the inter-terminal distance L is 1.8 (m). This threshold resistivity is higher than when the drive voltage Vin is 42 (V) or 50 (V). In other words, if the surface resistivity Rs is 180 (Ω/sq) or less, the transmittance will be saturated in all unit areas N of the light control sheet where the distance L between the terminals is 1.8 (m), and the light control will not be possible. The entire surface of the sheet changes from opaque to transparent.

Note that the threshold resistivity when the drive voltage Vin is 60 (V) over the entire range of the distance L between terminals from 1.8 (m) to 4.0 (m) is when the drive voltage Vin is 50 (V). ). For example, when the drive voltage Vin is 60 (V) and the distance L between terminals is 4.0 (m), the threshold resistivity is 40 (Ω/sq).

Further, when the drive voltage Vin is 60 (V), the degree of decrease in the threshold resistivity with respect to an increase in the inter-terminal distance L is greater than when the drive voltage Vin is 50 (V).
The threshold resistivity described above is expressed by the above relational expression, which is an approximate expression, using the voltage ratio Vt, which is the ratio of the drive voltage Vin to the threshold voltage Von, and the inter-terminal distance L as variables. The above relational expression indicates that the light control sheet and the light control device have the following [Characteristics 1] to [Characteristics 4].

[Characteristic 1] When the threshold voltages Von are mutually equal and the inter-terminal distances L are different from each other, the larger the inter-terminal distance L is, the lower the surface resistivity Rs is.
[Characteristic 2] When the threshold voltages Von are mutually equal and the inter-terminal distances L are different from each other, the larger the inter-terminal distance L is, the higher the drive voltage Vin is.

[Characteristic 3] When the threshold voltages Von are mutually different and the inter-terminal distances L are mutually different, the larger the inter-terminal distance L and the higher the threshold voltage Von, the lower the surface resistivity Rs.
[Characteristic 4] When the threshold voltages Von are mutually different and the inter-terminal distances L are mutually different, the driving voltage Vin is higher as the inter-terminal distance L is larger and the threshold voltage Von is higher.

As described above, according to the above embodiment, the following effects can be obtained.
(1) Since the surface resistivity Rs of each transparent electrode layer 12 satisfies the above relational expression, even if a voltage drop occurs between the transparent electrode layers 12A and 12B, the voltage applied between the transparent electrode layers 12A and 12B The voltage applied to the light control sheet is equal to or higher than the threshold voltage Von throughout the long axis direction DL of the light control sheet. As a result, the uniformity of transmittance increases within the plane of the light control sheet.

(2) Liquid crystal capacitance C1 is 5×10 ^-2 (μF) or more and 1×10 ^-1 (μF) or less, and liquid crystal resistance R1 is 0.5 M (Ω/sq) or more and 1.5 M (Ω/sq) In the case below, the effect based on the circuit simulation described above, that is, the effectiveness of increasing the uniformity of transmittance increases.

(3) When the drive voltage Vin is 50 (V) or less, the light control sheet can be driven at an extra low voltage or less, so it is possible to improve the safety in driving the light control sheet.
(4) When the drive voltage Vin is 42 (V) or less, the light control sheet can be driven at a safe extra low voltage or less, so it is possible to further improve the safety in driving the light control sheet.

(5) If the distance L between terminals is 1.8 m or less, the drive voltage Vin is 50 (V) or less, the threshold voltage Von is 40 (V) or less, and the surface resistivity is 120 (Ω/sq) or less, the drive voltage Although Vin is below the special low voltage, a voltage of 40 V or more, which is the threshold voltage Von, can be applied to the entire area between the transparent electrode layers 12A and 12B. Therefore, in a light control sheet in which the distance between terminals is 1.8 (m) or less, the effectiveness of increasing the uniformity of transmittance within the surface of the light control sheet is increased.

(6) When the distance L between terminals is 4.0 (m) or less, the drive voltage Vin is 50 (V) or less, the threshold voltage Von is 40 (V) or less, and the surface resistivity is 30 (Ω/sq) or less Although the drive voltage Vin is below the special low voltage, a voltage of 40 V or more, which is the threshold voltage Von, can be applied to the entire area between the transparent electrode layers 12A and 12B. Therefore, in a light control sheet in which the distance between terminals is 4.0 (m) or less, the effectiveness of increasing the uniformity of transmittance within the plane of the light control sheet is increased.

Note that the above embodiment can be modified and implemented as follows.
[Drive part]
- The drive unit 30 can also include an input unit that inputs at least one of the inter-terminal distance L and the threshold voltage Von from the outside, and a storage unit that stores various data.

- For example, the storage unit included in the drive unit 30 stores 40 (V) as the initial value of the threshold voltage Von, stores 100 (Ω/sq) as the initial value of the surface resistivity Rs, and further stores the above formula (2). ) is memorized. Then, the drive unit 30 applies the inter-terminal distance L input from the input unit and each initial value to the above relational expression, calculates a voltage that satisfies the above relational expression as the drive voltage Vin, and calculates the calculated drive voltage Vin. The voltage Vin may be output as an alternating current voltage. Note that the drive unit 30 is not limited to outputting the drive voltage Vin based on the above relational expression, but may output the drive voltage Vin such that the larger the distance L between the terminals input to the drive unit is, the higher the drive voltage Vin is. good.

- For example, the storage unit included in the drive unit 30 stores 1.8 (m) as the initial value of the inter-terminal distance L, stores 100 (Ω/sq) as the initial value of the surface resistivity Rs, and further stores the above-mentioned value. The relational expression shown in equation (2) is stored. Then, the drive unit 30 applies the threshold voltage Von input from the input unit and each initial value to the above relational expression, calculates a voltage that satisfies the above relational expression as the drive voltage Vin, and calculates the calculated drive voltage. Vin may be output as an alternating voltage. Note that the drive unit 30 is not limited to outputting the drive voltage Vin based on the above relational expression, and may output the drive voltage Vin such that the larger the threshold voltage Von input to the drive unit is, the higher the drive voltage Vin is. .

- For example, the storage unit included in the drive unit 30 stores 100 (Ω/sq) as the initial value of the surface resistivity Rs, and further stores the above relational expression. Then, the drive unit 30 applies the inter-terminal distance L input from the input unit, the threshold voltage Von input from the input unit, and each initial value to the above relational expression, and converts the voltage satisfying the above relational expression into the drive voltage. The driving voltage Vin may be calculated as Vin, and the calculated driving voltage Vin may be output as an alternating current voltage. Note that the drive unit 30 is not limited to outputting the drive voltage Vin based on the above relational expression, but the larger the distance L between the terminals input to the drive unit is, the higher the drive voltage Vin is, and the threshold voltage input to the drive unit is increased. The drive voltage Vin may be output so that the higher Von is, the higher the drive voltage Vin is.

- The liquid crystal capacitance C1 may be greater than or equal to 5×10 ⁻² (μF) and less than or equal to 1×10 ⁻¹ (μF). The liquid crystal resistance R1 may be greater than or equal to 0.5 M (Ω/sq) and less than or equal to 1.5 M (Ω/sq). If the light control sheet satisfies these ranges, the same result as the circuit simulation described above can be obtained, and the effect based on satisfying the above relational expression, which is an approximate expression derived from the same result, that is, the light control sheet The effectiveness of achieving the effect of increasing the uniformity of transmittance within the plane increases. Note that if another functional layer such as the alignment layer 14 is interposed between the liquid crystal layer 11 and the transparent electrode layer 12, the liquid crystal capacitance C1 is the capacitance of the liquid crystal layer 11 including the capacitance of the other functional layer. Further, the resistance including the resistance value of the liquid crystal layer 11 and the resistance value of other functional layers is defined as a liquid crystal resistance R1.

DL...long axis direction, L...distance between terminals, N...unit area, Rs...surface resistivity, Von...threshold voltage, Vin...drive voltage, 10, 10N, 10R...light control sheet, 11...liquid crystal layer, 12... Transparent electrode layer, 12A...first transparent electrode layer, 12B...second transparent electrode layer, 13...transparent support layer, 13A...first transparent support layer, 13B...second transparent support layer, 14...alignment layer, 14A...th 1 alignment layer, 14B...second alignment layer, 20...terminal, 20A...first terminal, 20B...second terminal, 30...driver.

Claims (7)

a first transparent electrode layer having a first terminal;
a second transparent electrode layer having a second terminal;
A liquid crystal layer located between the first transparent electrode layer and the second transparent electrode layer, the liquid crystal layer comprising a polymer transparent resin layer defining a plurality of voids, and a liquid crystal composition filling the voids. comprising a layer;
The first terminal and the second terminal are located at both ends of the light control sheet in the longitudinal direction,
A voltage applied between the first terminal and the second terminal is a driving voltage Vin,
The threshold value of the voltage when the light control sheet for threshold value specification having a unit area changes from opaque to transparent or from transparent to opaque by application of the voltage is the threshold voltage Von,
The shortest distance between the first terminal and the second terminal is an inter-terminal distance L (m),
The distance L between the terminals is 1.8 (m) or more and 4.0 (m) or less,
A light control sheet,
The light control sheet for specifying the threshold value is
The light control sheet has the same layer structure as a part of the light control sheet having a width of 0.1 (m) in each of the width direction perpendicular to the long axis direction and the long axis direction, and The threshold value when the voltage is applied between the terminals of the light control sheet is the threshold voltage Von,
The terminal provided on the light control sheet for specifying the threshold value is:
terminals arranged at both ends of the longitudinal direction of the light control sheet for threshold specification and connected to the first transparent electrode layer for threshold specification; and the second transparent terminal of the light control sheet for threshold specification. a terminal connected to an electrode layer, the length of the terminal in the width direction is 0.1 (m), and the length in the long axis direction is 5 (mm),
The transparent state is such that the haze value of the light control sheet for specifying the threshold value does not change with respect to the voltage at 50% or less ,
The opacity is a state in which the haze value of the light control sheet for specifying the threshold value does not change with respect to the voltage at 95% or more ,
The surface resistivity Rs (Ω/sq) of the first transparent electrode layer and the second transparent electrode layer satisfies formula (1),
Rs≦(-A×Vt+B)×L ^-C ... Formula (1)
Vt=Von/Vin, A=1.5×10 ³ , B=1.5×10 ³ , C=1.9,
Light control sheet. The capacitance value of the liquid crystal layer is 5×10 ⁻² (μF) or more and 1×10 ⁻¹ (μF) or less,
The light control sheet according to claim 1, wherein the liquid crystal layer has a resistance value of 0.5 M (Ω/sq) or more and 1.5 M (Ω/sq) or less. The driving voltage Vin is 50 (V) or less,
The light control sheet according to claim 1 or 2. The driving voltage Vin is 42 (V) or less,
The light control sheet according to any one of claims 1 to 3. a first transparent electrode layer having a first terminal;
a second transparent electrode layer having a second terminal;
A liquid crystal layer located between the first transparent electrode layer and the second transparent electrode layer, the liquid crystal layer comprising a polymer transparent resin layer defining a plurality of voids, and a liquid crystal composition filling the voids. layer and
A light control sheet comprising;
a drive unit that applies a voltage between the first terminal and the second terminal;
Equipped with
The first terminal and the second terminal are located at both ends of the light control sheet in the longitudinal direction,
The threshold value of the voltage when the light control sheet for threshold value specification having a unit area changes from opaque to transparent or from transparent to opaque by application of the voltage is the threshold voltage Von,
The shortest distance between the first terminal and the second terminal is an inter-terminal distance L (m),
The distance L between the terminals is 1.8 (m) or more and 4.0 (m) or less,
The resistance value per unit area of the first transparent electrode layer and the second transparent electrode layer is a surface resistivity Rs (Ω/sq),
The light control sheet for specifying the threshold value is
The light control sheet has the same layer structure as a part of the light control sheet having a width of 0.1 (m) in each of the width direction perpendicular to the long axis direction and the long axis direction, and The threshold value when the voltage is applied between the terminals of the light control sheet is the threshold voltage Von,
The terminal provided on the light control sheet for specifying the threshold value is:
terminals arranged at both ends of the longitudinal direction of the light control sheet for threshold specification and connected to the first transparent electrode layer for threshold specification; and the second transparent terminal of the light control sheet for threshold specification. a terminal connected to an electrode layer, the length of the terminal in the width direction is 0.1 (m), and the length in the long axis direction is 5 (mm),
The transparent state is such that the haze value of the light control sheet for specifying the threshold value does not change with respect to the voltage at 50% or less ,
The opacity is a state in which the haze value of the light control sheet for specifying the threshold value does not change with respect to the voltage at 95% or more ,
The drive unit applies a drive voltage Vin as the voltage so as to satisfy equation (1).
Rs≦(-A×Vt+B)×L ^-C ... Formula (1)
Vt=Von/Vin, A=1.5×10 ³ , B=1.5×10 ³ , C=1.9,
Dimmer. The driving voltage Vin is 50 (V) or less,
The threshold voltage Von is 40 (V) or less,
The surface resistivity Rs is 30 (Ω/sq) or less,
The light control device according to claim 5. a first transparent electrode layer having a first terminal;
a second transparent electrode layer having a second terminal;
A liquid crystal layer located between the first transparent electrode layer and the second transparent electrode layer, the liquid crystal layer comprising a polymer transparent resin layer defining a plurality of voids, and a liquid crystal composition filling the voids. layer and
A light control sheet comprising;
a drive unit that applies a voltage between the first terminal and the second terminal;
Equipped with
The first terminal and the second terminal are located at both ends of the light control sheet in the longitudinal direction,
The threshold value of the voltage when the light control sheet for threshold value specification having a unit area changes from opaque to transparent or from transparent to opaque by application of the voltage is the threshold voltage Von,
The shortest distance between the first terminal and the second terminal is an inter-terminal distance L (m),
The distance L between the terminals is 1.8 (m) or more and 4.0 (m) or less,
The resistance value per unit area of the first transparent electrode layer and the second transparent electrode layer is a surface resistivity Rs (Ω/sq),
The light control sheet for specifying the threshold value is
The light control sheet has the same layer structure as a part of the light control sheet having a width of 0.1 (m) in each of the width direction perpendicular to the long axis direction and the long axis direction, and The threshold value when the voltage is applied between the terminals of the light control sheet is the threshold voltage Von,
The terminal provided on the light control sheet for specifying the threshold value is:
terminals arranged at both ends of the longitudinal direction of the light control sheet for threshold specification and connected to the first transparent electrode layer for threshold specification; and the second transparent terminal of the light control sheet for threshold specification. a terminal connected to an electrode layer, the length of the terminal in the width direction is 0.1 (m), and the length in the long axis direction is 5 (mm),
The transparent state is such that the haze value of the light control sheet for specifying the threshold value does not change with respect to the voltage at 50% or less ,
The opacity is a state in which the haze value of the light control sheet for specifying the threshold value does not change with respect to the voltage at 95% or more ,
When applying the drive voltage Vin as the voltage, the drive unit increases the drive voltage Vin as the distance L between the terminals input to the drive unit increases, and increases the threshold voltage Von input to the drive unit. The higher the driving voltage Vin is, the higher the driving voltage Vin is.
Dimmer.