JP2021182093A - Light control unit, light control device and method for driving light control unit - Google Patents

Abstract

To provide: a light control unit capable of suppressing the occurrence of a flicker in a light control sheet; a light control device; and a method for driving the light control unit.SOLUTION: A light control unit includes a light control sheet 21N including a first transparent electrode layer 31, a second transparent electrode layer 32 and a light control layer 33 sandwiched by the first transparent electrode layer 31 and the second transparent electrode layer 32 and including a plurality of liquid crystal molecules. An effective voltage rate from the point of starting to apply an AC voltage between the first transparent electrode layer 31 and the second transparent electrode layer 32 to the point of lapsing one period is 0.9 or more, and the effective voltage rate is the ratio (SE/SR) of the total (SE) of the arrival values of the AC voltage to the total (SR) of the effective values of the AC voltage from the point of starting to apply the AC voltage to the point of lapsing one period.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dimming unit, a dimming device, and a method for driving the dimming unit.

The dimming device includes a dimming unit provided with a dimming sheet and a driving device. The light control sheet includes a light control layer and a pair of transparent electrode layers that sandwich the light control layer. The dimming layer includes a liquid crystal composition and a polymer layer having voids filled with the liquid crystal composition. The drive device applies an AC voltage between the pair of transparent electrode layers included in the dimming sheet, thereby driving the dimming sheet. When the dimming sheet is a normal type, the dimming sheet is cloudy when no AC voltage is applied between the transparent electrodes, while the dimming sheet is while the AC voltage is applied. Is transparent. On the other hand, when the dimming sheet is a reverse type, the dimming sheet is transparent while the AC voltage is applied while the AC voltage is not applied between the transparent electrodes. , The dimming sheet is cloudy (see, for example, Patent Document 1).

Japanese Patent No. 6610845

By the way, when the dimming sheet is driven by applying an AC voltage, segregation of ionic impurities contained in the liquid crystal composition is suppressed, so that deterioration of the liquid crystal composition is suppressed. On the other hand, since the orientation of the liquid crystal molecules changes according to the frequency of the AC voltage applied between the layers of the pair of transparent electrodes, the dimming sheet becomes cloudy and transparent as the orientation of the liquid crystal molecules changes. It has a state periodically. As a result, depending on the conditions for driving the dimming sheet, the cycle of switching between transparency and cloudiness reaches the time resolution of a person, which may cause flicker that is observable by a person on the dimming sheet.

It is an object of the present invention to provide a dimming unit, a dimming device, and a method for driving the dimming unit, which can suppress the occurrence of flicker in the dimming sheet.

The dimming unit for solving the above problems is sandwiched between the first transparent electrode layer, the second transparent electrode layer, the first transparent electrode layer, and the second transparent electrode layer, and includes a plurality of liquid crystal molecules. It is provided with a dimming layer and a dimming sheet provided with. The effective voltage ratio from the time when the application of the AC voltage between the first transparent electrode layer and the second transparent electrode layer is started to the time when one cycle elapses is 0.9 or more, and the effective voltage ratio is , The ratio of the sum of the reached values of the AC voltage (SE) to the sum of the effective values of the AC voltage (SR) from the time when the application of the AC voltage is started to the time when the one cycle elapses (SE / SR). Is.

According to the above configuration, when the effective voltage ratio of the dimming unit is 0.9 or more, the dimming layer is among the AC voltages applied between the first transparent electrode layer and the second transparent electrode layer. It is possible to increase the proportion that contributes to the driving of the liquid crystal molecules contained therein, thereby increasing the responsiveness of the liquid crystal molecules. As a result, it is possible to suppress the occurrence of flicker in the dimming sheet.

The dimming unit for solving the above problems is sandwiched between the first transparent electrode layer, the second transparent electrode layer, the first transparent electrode layer, and the second transparent electrode layer, and includes a plurality of liquid crystal molecules. It is provided with a dimming layer and a dimming sheet provided with. When the AC voltage applied between the first transparent electrode layer and the second transparent electrode layer has a frequency of 30 Hz or more and 60 Hz or less, and is a time constant (milliseconds) or less calculated by the following function. Has a constant.
y = 101.9919 × (1 / x)

According to the above configuration, the dimming unit is a liquid crystal display included in the dimming layer when the frequency of the AC voltage applied between the first transparent electrode layer and the second transparent electrode layer is 30 Hz or more and 60 Hz or less. Since the time constant is small enough to enhance the responsiveness of the molecule, it is possible to suppress the occurrence of flicker in the light control sheet.

The dimming device for solving the above-mentioned problems includes the dimming unit and a driving unit for applying the AC voltage between the first transparent electrode layer and the second transparent electrode layer.

In the dimming device, the driving unit may apply the AC voltage having a rectangular wavy shape between the first transparent electrode layer and the second transparent electrode layer. According to this configuration, by applying an AC voltage having a rectangular wave shape between the first transparent electrode layer and the second transparent electrode layer, as compared with the case where an AC voltage having a sine wave shape or a sawtooth shape is applied. Therefore, it is possible to suppress the formation of a transient state in the orientation of the liquid crystal molecules. This makes it possible to suppress the occurrence of flicker in the dimming sheet.

The dimming device for solving the above problems includes a drive unit that outputs a voltage signal of a square wave, a first transparent electrode layer, a second transparent electrode layer, the first transparent electrode layer, and the second transparent electrode. A dimming unit including a dimming layer sandwiched between the layers and containing a plurality of liquid crystal molecules, and a dimming sheet whose haze value changes according to a voltage applied by the driving unit. The response function f (t) showing the relationship between the period T of the voltage signal, the DC voltage corresponding to the amplitude of the square wave, and the voltage between the transparent electrodes in the dimming unit when the DC voltage is applied. ) And, so that the following equation holds.

The dimming device for solving the above problems includes a drive unit that outputs a voltage signal of a square wave, a first transparent electrode layer, a second transparent electrode layer, the first transparent electrode layer, and the second transparent electrode. It includes a dimming layer sandwiched between the layers and containing a plurality of liquid crystal molecules, and a dimming unit including a dimming sheet whose haze value changes according to a voltage applied by the driving unit. Using the period T of the voltage signal and the time constant τ of the dimming unit, the following equation is established.

According to each of the above configurations, the dimming device is configured to satisfy the above equation, so that the dimming layer is among the AC voltages applied between the first transparent electrode layer and the second transparent electrode layer. It is possible to increase the proportion that contributes to the driving of the liquid crystal molecules contained therein, thereby increasing the responsiveness of the liquid crystal molecules. As a result, it is possible to suppress the occurrence of flicker in the dimming sheet.

The method for driving the dimming unit for solving the above problems is to sandwich a plurality of liquid crystal molecules between the first transparent electrode layer, the second transparent electrode layer, and the first transparent electrode layer and the second transparent electrode layer. It includes applying an AC voltage between the first transparent electrode layer and the second transparent electrode layer to the dimming unit provided with the dimming sheet including the dimming layer. Applying an AC voltage means that the first transparent electrode layer and the second transparent electrode layer have an effective voltage ratio of 0.9 or more from the time when the application of the AC voltage is started to the time when one cycle elapses. The effective voltage ratio includes the application of an AC voltage in between, and the effective voltage ratio is the value reached by the AC voltage with respect to the sum of the effective values of the AC voltage (SR) from the time when the application of the AC voltage is started to the time when one cycle elapses. It is the ratio (SE / SR) of the sum (SE).

The method for driving the dimming unit for solving the above problems is to sandwich a plurality of liquid crystal molecules between the first transparent electrode layer, the second transparent electrode layer, and the first transparent electrode layer and the second transparent electrode layer. It includes applying an AC voltage between the first transparent electrode layer and the second transparent electrode layer to the dimming unit provided with the dimming sheet including the dimming layer. Applying an AC voltage applies an AC voltage having a frequency of 30 Hz or more and 60 Hz or less to the first transparent electrode layer and the second transparent electrode so that the time constant of the dimming sheet is a value calculated by the following function. Apply between layers.
y = 101.9919 × (1 / x)

According to the present invention, it is possible to suppress the occurrence of flicker in the dimming sheet.

FIG. 3 is a cross-sectional view showing the structure of a dimming device provided with a normal type dimming sheet. FIG. 3 is a cross-sectional view showing the structure of a dimming device including a reverse type dimming sheet. Equivalent circuit of dimmer. The graph which shows an example in the relationship between time in a dimming unit and a voltage rise rate. The graph which shows an example in the relationship between time in a dimming unit and a voltage rise rate. A graph showing the relationship between frequency and time constant. The plan view which shows typically the structure of the dimming unit used in Test Example 1. The graph which shows the relationship between the time and the voltage rise rate in a unit 1 to a unit 4. A block diagram for explaining a method of measuring flicker. The graph which shows the relationship between the effective voltage rate and the flicker rate when the AC voltage having a frequency of 30Hz is applied. The graph which shows the relationship between the effective voltage rate and the flicker rate when the AC voltage having a frequency of 40Hz is applied. The graph which shows the relationship between the effective voltage rate and the flicker rate when the AC voltage having a frequency of 50Hz is applied. The plan view which shows typically the structure of the dimming unit used in Test Example 2. A graph showing the relationship between time and the rate of voltage rise. The graph which shows the relationship between the effective voltage rate and the flicker rate when the AC voltage having a frequency of 30Hz is applied. The graph which shows the relationship between the effective voltage rate and the flicker rate when the AC voltage having a frequency of 40Hz is applied. The graph which shows the relationship between the effective voltage rate and the flicker rate when the AC voltage having a frequency of 50Hz is applied.

An embodiment of a dimming unit, a dimming device, and a method of driving the dimming unit will be described with reference to FIGS. 1 to 17. Hereinafter, the dimming device, the driving method of the dimming unit, and the test example will be described in order.

[Dimmer]
The dimming device will be described with reference to FIGS. 1 to 6. The dimming device of the present disclosure includes a dimming unit and a drive unit. The dimming sheet provided in the dimming unit may be a normal type or a reverse type. Hereinafter, a dimming device including a normal type dimming sheet will be described with reference to FIG. 1, and a dimming unit including a reverse type dimming device will be described with reference to FIG.

As shown in FIG. 1, the dimming device 10 can include a dimming unit 11 provided with a normal type dimming sheet 21N and a drive unit 12. The light control sheet 21N includes a first transparent electrode layer 31, a second transparent electrode layer 32, and a light control layer 33. The light control sheet 21N further includes a first transparent base material 34 that supports the first transparent electrode layer 31, and a second transparent base material 35 that supports the second transparent electrode layer 32.

The dimming unit 11 includes a first electrode 22A attached to a part of the first transparent electrode layer 31 and a second electrode 22B attached to a part of the second transparent electrode layer 32. The dimming unit 11 further includes a first wiring 23A connected to the first electrode 22A and a second wiring 23B connected to the second electrode 22B. The first electrode 22A is connected to the drive unit 12 by the first wiring 23A, and the second electrode 22B is connected to the drive unit 12 by the second wiring 23B.

The first transparent electrode layer 31 and the second transparent electrode layer 32 have a light transmission property for transmitting visible light. The light transmittance of the first transparent electrode layer 31 enables visual recognition of an object through the dimming sheet 21N. The light transmission of the second transparent electrode layer 32 enables visual recognition of an object through the dimming sheet 21N, similarly to the light transmission of the first transparent electrode layer 31.

The material for forming the transparent electrode layers 31 and 32 is composed of, for example, indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, and poly (3,4-ethylenedioxythiophene). It may be any one selected from the group to be treated.

The dimming layer 33 includes a transparent polymer layer and a liquid crystal composition. The transparent polymer layer has voids in which the liquid crystal composition is filled. The liquid crystal composition is filled in the voids of the transparent polymer layer. The liquid crystal composition contains liquid crystal molecules. An example of a liquid crystal molecule is composed of a Schiff base type, an azo type, an azoxy type, a biphenyl type, a terphenyl type, a benzoic acid ester type, a trans type, a pyrimidine type, a cyclohexanecarboxylic acid ester type, a phenylcyclohexane type, and a dioxane type. It is one of the groups to be selected.

The holding type of the liquid crystal composition is any one selected from the group consisting of a polymer network type, a polymer dispersed type, and a capsule type. The polymer network type has a transparent polymer network having a three-dimensional network, and holds the liquid crystal composition in the network-like voids communicating with each other. The polymer network is an example of a transparent polymer layer. The polymer-dispersed type has a large number of isolated voids in the transparent polymer layer, and holds the liquid crystal composition in the voids dispersed in the polymer layer. The capsule type holds the liquid crystal composition having a capsule shape in the transparent polymer layer. In addition to the liquid crystal molecules described above, the liquid crystal composition may contain a monomer for forming a transparent polymer layer, a dichroic dye, and the like.

The material forming the transparent base materials 34 and 35 may be a synthetic resin or an inorganic compound. Synthetic resins include, for example, polyesters, polyacrylates, polycarbonates, and polyolefins. The polyester is, for example, polyethylene terephthalate and polyethylene naphthalate. The polyacrylate is, for example, polymethylmethacrylate. The inorganic compound is, for example, silicon dioxide, silicon oxynitride, silicon nitride and the like.

Each of the electrodes 22A and 22B is, for example, flexible printed circuit boards (FPC). The FPC includes a support layer, a conductor portion, and a protective layer. The conductor portion is sandwiched between the support layer and the protective layer. The support layer and the protective layer are formed of an insulating synthetic resin. The support layer and the protective layer are formed of, for example, polyimide. The conductor portion is formed of, for example, a metal thin film. The material forming the metal thin film may be, for example, copper. The electrodes 22A and 22B are not limited to FPCs, and may be, for example, metal tapes.

The electrodes 22A and 22B are attached to the transparent electrode layers 31 and 32 by a conductive adhesive layer (not shown). In the portions of the electrodes 22A and 22B connected to the conductive adhesive layer, the conductor portion is exposed from the protective layer or the support layer.

The conductive adhesive layer is, for example, an anisotropic conductive film (ACF: Anisotropic Conductive Film), an anisotropic conductive paste (ACP: Anisotropic Conductive Paste), an isotropic conductive film (ICF: Isotropic Conductive Film), and the like. It may be formed by an anisotropic conductive paste (ICP) or the like. From the viewpoint of handleability in the manufacturing process of the dimming device 10, the conductive adhesive layer is preferably an anisotropic conductive film.

Each of the wirings 23A and 23B is formed by, for example, a metal wire and an insulating layer covering the metal wire. The wire is made of, for example, copper.
The dimming layer 33 changes the orientation of the liquid crystal molecules in response to the change in voltage generated between the two transparent electrode layers 31 and 32. The change in the orientation of the liquid crystal molecules changes the degree of scattering, the degree of absorption, and the degree of transmission of visible light entering the light control layer 33. The normal type dimming sheet 21N has a relatively high light transmittance when the dimming sheet 21N is energized. The normal type dimming sheet 21N has a relatively low light transmittance when the dimming sheet 21N is not energized. For example, the normal type dimming sheet 21N has a transparent state when the dimming sheet 21N is energized, and has an opaque state when the dimming sheet 21N is not energized. As described above, in the dimming sheet 21N, the haze value in the dimming sheet 21N changes according to the AC voltage applied between the transparent electrode layers 31 and 32. The dimming sheet 21N has a relatively high haze value when the dimming sheet 21N is not energized. On the other hand, the dimming sheet 21N has a relatively low haze value when the dimming sheet 21N is energized.

The drive unit 12 applies an AC voltage between the first transparent electrode layer 31 and the second transparent electrode layer 32. The drive unit 12 preferably applies an AC voltage having a rectangular wavy shape between the pair of transparent electrode layers 31 and 32. In other words, the drive unit 12 preferably outputs a square wave voltage signal.

The dimming sheet 21N is attached to a window provided in a moving body such as a vehicle or an aircraft. Further, the dimming sheet 21N is attached to, for example, windows provided in various buildings such as houses, stations, and airports, partitions installed in offices, show windows installed in stores, screens for projecting images, and the like. .. The shape of the dimming sheet 21N may be flat or curved.

As shown in FIG. 2, the dimming device 10 can include a dimming unit 11 provided with a reverse type dimming sheet 21R and a drive unit 12. The light control sheet 21R includes a first transparent electrode layer 31, a second transparent electrode layer 32, a first alignment film 36, a second alignment film 37, and a light control layer 33. The dimming layer 33 is located between the first alignment film 36 and the second alignment film 37. The first alignment film 36 is located between the dimming layer 33 and the first transparent electrode layer 31 and is in contact with the dimming layer 33. The second alignment film 37 is located between the light control layer 33 and the second transparent electrode layer 32, and is in contact with the light control layer 33.

The material for forming the first alignment film 36 and the second alignment film 37 is an organic compound, an inorganic compound, and a mixture thereof. The organic compound is, for example, polyimide, polyamide, polyvinyl alcohol, cyanide compound and the like. Inorganic compounds are silicon oxide, zirconium oxide and the like. The material for forming the alignment films 36 and 37 may be silicone. Silicone is a compound having an inorganic part and an organic part.

The first alignment film 36 and the second alignment film 37 are, for example, a vertical alignment film or a horizontal alignment film. The vertical alignment film is such that the liquid crystal molecules are perpendicular to the surface opposite to the surface in contact with the first transparent electrode layer 31 and the surface opposite to the surface in contact with the second transparent electrode layer 32. Orient the major axis direction. The horizontal alignment film is a liquid crystal molecule so as to be substantially parallel to the surface opposite to the surface in contact with the first transparent electrode layer 31 and the surface opposite to the surface in contact with the second transparent electrode layer 32. Orients the long axis direction of. As described above, regardless of which of the alignment films 36 and 37 is, the alignment films 36 and 37 regulate the orientation of the plurality of liquid crystal molecules included in the dimming layer 33.

The reverse type dimming sheet 21R has a relatively low light transmittance when the dimming sheet 21R is energized. The reverse type dimming sheet 21R has a relatively high light transmittance when the dimming sheet 21R is not energized. For example, the reverse type dimming sheet 21R has an opaque state when the dimming sheet 21R is energized, and has a transparent state when the dimming sheet 21R is not energized. As described above, in the dimming sheet 21R, the haze value in the dimming sheet 21R changes according to the AC voltage applied between the transparent electrode layers 31 and 32. The dimming sheet 21R has a relatively low haze value when the dimming sheet 21R is not energized. On the other hand, the dimming sheet 21R has a relatively high haze value when the dimming sheet 21R is energized.

FIG. 3 is an equivalent circuit of the dimming device 10.
As shown in FIG. 3, in the equivalent circuit of the dimming device 10, the first transparent electrode layer 31 is regarded as the resistance component R31, and the second transparent electrode layer 32 is regarded as the resistance component R32. The dimming layer 33 is regarded as a parallel circuit of the capacitance component C33 and the resistance component R33. The resistance component R33 of the dimming layer 33 is significantly larger than the resistance components R31 and R32. Although not shown in FIG. 3, in the dimming device 10, the electrodes 22A and 22B and the wirings 23A and 23B are also regarded as resistance components.

As described above, since the equivalent circuit of the dimming device 10 is an RC circuit formed by the resistance component R component and the capacitance component C, the time constant τ in the circuit is expressed by the following equation.
τ = RC

FIG. 4 is a graph showing an example of the relationship between the time and the voltage rise rate in the dimming unit 11. Note that FIG. 4 shows the relationship between the time and the voltage rise rate when an AC voltage having a frequency of 50 Hz is applied between the pair of transparent electrode layers 31 and 32.

The voltage rise rate shown in FIG. 4 is the ratio (VR) of the reached value (VR) of the AC voltage to the effective value (VE) of the AC voltage applied between the first transparent electrode layer 31 and the second transparent electrode layer 32. / VE). The reached value of the AC voltage is a value reached by the voltage applied to the dimming unit 11 at each time point within the application period of the AC voltage. The voltage rise rate can be calculated at each time point within the period in which the AC voltage is applied between the pair of transparent electrode layers 31 and 32. The voltage rise rate is a value that depends on the time constant τ in the dimming device 10. The voltage rise rate tends to increase as the time constant τ becomes smaller.

It is possible to define the effective voltage factor in the curve of the voltage rise rate. The effective voltage ratio is the sum of the reached values (VR) of the AC voltage with respect to the sum of the effective values (VE) of the AC voltage (VE) from the time when the application of the AC voltage is started to the time when one cycle elapses. Ratio (SR / SE).

In the example shown in FIG. 4, since an AC voltage having a frequency of 50 Hz is applied, one cycle is 20 milliseconds (ms). Therefore, the sum of the effective values (VE) (SE) is the sum of the effective values (VE) from 0 ms to 20 ms (SE), and is the area surrounded by the rectangle shown by the thick line in FIG. Corresponds to the first area of. On the other hand, the total sum (SR) of the reached values (VR) does not exceed the voltage rise rate curve in the region partitioned by the rectangle shown by the thick line in FIG. 4 and the voltage rise rate curve. It corresponds to the second area of the area, that is, the area with dots. Therefore, the effective voltage ratio is the ratio of the ratio of the second area to the first area (second area / first area).

In the dimming unit 11 of the present disclosure, the effective voltage ratio from the time when the application of the AC voltage between the pair of transparent electrode layers 31 and 32 is started to the time when one cycle elapses is 0.9 or more. When the effective voltage ratio of the dimming unit 11 is 0.9 or more, the liquid crystal display included in the dimming layer 33 among the AC voltages applied between the first transparent electrode layer 31 and the second transparent electrode layer 32. It is possible to increase the proportion that contributes to the driving of the molecule, thereby increasing the responsiveness of the liquid crystal molecule. As a result, it is possible to suppress the occurrence of flicker in the dimming sheets 21N and 21R.

Further, as described above, the dimming device 10 of the present disclosure includes a driving unit 12 for outputting a voltage signal of a square wave, and a dimming unit 11 including dimming sheets 21N and 21R. The dimming device 10 has a period T of a voltage signal, a DC voltage corresponding to the amplitude of a square wave, and a voltage between the transparent electrode layers 31 and 32 in the dimming unit 11 when the DC voltage is applied. Using the response function f (t) indicating the relationship, the following equation is configured to hold.

Further, the dimming device 10 of the present disclosure is configured so that the following equation is established by using the period T of the voltage signal and the time constant τ of the dimming unit 11.

That is, the above-mentioned response function f (t) can be expressed by the equation (2) using the period T of the voltage signal and the time constant τ of the dimming unit 11.

In this way, since the dimming device 10 is configured to satisfy the above-mentioned equation, among the AC voltages applied between the first transparent electrode layer 31 and the second transparent electrode layer 32, the dimming layer 33 It is possible to increase the proportion of the liquid crystal molecules contained in the light that contributes to the driving of the liquid crystal molecules, thereby increasing the responsiveness of the liquid crystal molecules. As a result, it is possible to suppress the occurrence of flicker in the dimming sheets 21N and 21R.

FIG. 5 shows an example of an effective voltage factor curve when the frequency of the AC voltage applied to the dimming sheets 21N and 21R is 30 Hz or more and 60 Hz or less and the effective voltage ratio is 0.9. ..

As shown in FIG. 5, in order to satisfy that the effective voltage rate is 0.9 or more in the range where the frequency of the AC voltage is 30 Hz or more and 60 Hz or less, the higher the frequency of the AC voltage, the more the curve of the voltage rise rate. It is required that the rise in the frequency is high. The higher the frequency of the AC voltage, the shorter the length of one cycle. Therefore, the higher the frequency of the AC voltage, the steeper the curve of the voltage rise rate is required.

FIG. 6 is a graph showing the relationship between the frequency (Hz) of the AC voltage applied between the pair of transparent electrode layers 31 and 32 and the time constant τ. The solid line shown in FIG. 6 is a set of time constants τ satisfying that the effective voltage factor is 0.9 at each frequency. Further, the broken line shown in FIG. 6 is an approximate curve of the effective voltage factor shown by the solid line.

As shown in FIG. 6, the dimming unit 11 of the present disclosure is calculated by the following function when the AC voltage applied between the pair of transparent electrode layers 31 and 32 has a frequency of 30 Hz or more and 60 Hz or less. It has a time constant of less than or equal to the time constant (milliseconds).
y = 101.9919 × (1 / x)

As a result, the dimming unit 11 has the responsiveness of the liquid crystal molecules contained in the dimming layer 33 when the frequency of the AC voltage applied between the pair of transparent electrode layers 31 and 32 is 30 Hz or more and 60 Hz or less. Has a time constant τ small enough to be able to increase. Therefore, it is possible to suppress the occurrence of flicker in the dimming sheets 21N and 21R.

The time constant τ when the effective voltage ratio satisfies 0.9 is 3.35 when the frequency of the AC voltage is 30 Hz, 2.55 when the frequency of the AC voltage is 40 Hz, and the AC voltage. It is 2.05 when the frequency of is 50 Hz, and 1.72 when the frequency of the AC voltage is 60 Hz. The higher the frequency of the AC voltage, the shorter the length of one cycle. Therefore, from the viewpoint of enhancing the responsiveness of the liquid crystal molecules in one cycle, the higher the frequency of the AC voltage, the more the time constant τ of the dimming unit 11 becomes. It is required to be small.

The effective voltage rate of the dimming unit 11 is due to the fact that the time constant τ of the dimming unit 11 has a time constant equal to or less than the time constant calculated by a curve that approximates the curve showing the relationship between the frequency and the time constant τ described above. Can have a value near 0.9 or less than 0.9. As a result, the responsiveness of the liquid crystal molecules contained in the dimming layer 33 is enhanced, so that the occurrence of flicker in the dimming sheets 21N and 21R is suppressed.

On the other hand, since the time constant τ satisfies these conditions, it is possible to drive the dimming sheets 21N and 21R while suppressing flicker by an AC voltage having a frequency of 30 Hz or more and 60 Hz or less. It is also possible to reduce the power consumed by driving the 21R.

As described above, the time constant τ possessed by the dimming unit 11 is the product of the resistance component R and the capacitance component C in the dimming device 10 which is an RC circuit. Therefore, the time constant τ possessed by the dimming unit 11 is the sheet resistance value of each of the transparent electrode layers 31 and 32, the resistance value of each of the electrodes 22A and 22B, and the interfacial resistance value between the first transparent electrode layer 31 and the first electrode 22A. , The value is determined by the interfacial resistance value between the second transparent electrode layer 32 and the second electrode 22B, the wiring resistance value in each of the wirings 23A and 23B, and the like. The smaller each of these resistance values, the smaller the time constant τ tends to be. Further, the time constant τ is a value determined by the distance between the electrodes, the areas of the dimming sheets 21N and 21R, and the dielectric constant of the dimming layer 33. The distance between the electrodes, the areas of the dimming sheets 21N and 21R, and the dielectric constant of the dimming layer 33 contribute to the capacitance component C of the dimming device 10. The larger the distance between the electrodes, the smaller the time constant τ tends to be, the smaller the area of the dimming sheets 21N and 21R, and the smaller the dielectric constant of the liquid crystal layer, the smaller the time constant τ tends to be.

[How to drive the dimming unit]
The driving method of the dimming unit 11 in the present disclosure includes applying an AC voltage between the pair of transparent electrode layers 31 and 32. When applying an AC voltage, an AC voltage is applied between the pair of transparent electrode layers 31 and 32 so that the effective voltage ratio from the time when the application of the AC voltage is started to the time when one cycle elapses is 0.9 or more. Apply. Alternatively, when applying an AC voltage, applying the AC voltage means that the AC voltage has a frequency of 30 Hz or more and 60 Hz or less so that the time constant of the dimming sheet is equal to or less than the value calculated by the above-mentioned function. Is applied between the pair of transparent electrode layers 31 and 32. As a result, the responsiveness of the liquid crystal molecules contained in the dimming layer 33 is enhanced, so that the dimming sheet 21N. It is possible to suppress the occurrence of flicker in 21R.

As described above, it is preferable that the drive unit 12 applies an AC voltage having a rectangular wavy shape between the pair of transparent electrode layers 31 and 32. By applying an AC voltage having a rectangular wave shape between the pair of transparent electrode layers 31 and 32, a transient state in the orientation of the liquid crystal molecules is compared with the case where an AC voltage having a sine wave shape or a sawtooth shape is applied. Is suppressed from being formed. As a result, the occurrence of flicker can be suppressed in the dimming sheets 21N and 21R.

[Test example]
A test example will be described with reference to FIGS. 7 to 17.
[Test Example 1]
Test Example 1 will be described with reference to FIGS. 7 to 12.

FIG. 7 shows the planar structure of the dimming unit 11 used in Test Example 1.
As shown in FIG. 7, the dimming unit 11 includes a normal type dimming sheet 21N. The dimming sheet 21N has a rectangular shape. The dimming unit 11 includes a first electrode 22A and a second electrode 22B which are located in the vicinity of one short side and have a shape extending along one short side. The first wiring 23A is connected to the first electrode 22A, and the second wiring 23B is connected to the second electrode 22B.

In the light control sheet 21N, a polymer-dispersed light control layer 33 was prepared, and the thickness of the light control layer 33 was 0.02 mm. Further, a PET film on which an ITO film is formed is prepared, and a first transparent electrode layer 31 supported by the first transparent base material 34 and a second transparent electrode layer supported by the second transparent base material 35 from the film are prepared. I got 32. The thickness of the ITO film was about 150 nm, and the thickness of the PET film was 0.01 mm. In the dimming sheet 21N, the length LL of the long side was set to 980 mm, and the length LS of the short side was set to 200 mm.

Further, the electrodes 22A and 22B were formed of copper tape. In each of the electrodes 22A and 22B, the length LE along the short side was set to 25 mm. The distance DE between the center of each of the electrodes 22A and 22B and the end of the short side was set to 50 mm in the direction in which the short side was extended. The wirings 23A and 23B were formed of copper wire.

In the dimming unit 11, it was found that the capacitance component C was 1.5 μF and the resistance component R was 200 Ω.
A metal clad resistor having a rated power of 50 W was prepared and inserted in series between the drive unit 12 and the dimming unit 11. At this time, a resistor having a resistance value of 1 kΩ, a resistor having a resistance value of 4.7 kΩ, and a resistor having a resistance value of 9.4 kΩ were prepared. Then, the voltage rise rate in the dimming unit in which each resistor is inserted and the voltage rise rate in the dimming unit in which the resistor is not inserted, that is, the dimming unit in which the resistance value of the resistor is 0Ω are calculated. bottom. The result of calculating the voltage rise rate was as shown in FIG.

In the following, the dimming unit in which the resistor is not inserted is the unit 1, and the dimming unit in which the resistor having the resistance value of 1 kΩ is inserted is the unit 2, the resistor having the resistance value of 4.7 kΩ. The dimming unit into which the is inserted is referred to as a unit 3, and the dimming unit into which a resistor having a resistance value of 9.4 kΩ is inserted is referred to as a unit 4, respectively.

As shown in FIG. 8, it was found that the smaller the resistance value of the resistor inserted in the dimming device, the steeper the curve of the voltage rise rate in the dimming unit 11. Note that FIG. 8 shows a curve of the voltage rise rate when the frequency of the AC voltage is 50 Hz.

When the frequency of the AC voltage is 30 Hz, the voltage rise rate at the time when one cycle has elapsed from the time when the application of the AC voltage is started is 1.000 in the unit 1 and the unit 2, and in the unit 3. It was 0.989, which was found to be 0.894 in Unit 4. When the frequency of the AC voltage is 40 Hz, the voltage rise rate at the time when one cycle has elapsed from the time when the application of the AC voltage is started is 1.000 in the unit 1 and the unit 2, and in the unit 3. It was 0.967, which was found to be 0.817 in Unit 4. When the frequency of the AC voltage is 50 Hz, the voltage rise rate at the time when one cycle has elapsed from the time when the application of the AC voltage is started is 1.000 in the unit 1 and the unit 2, and in the unit 3. It was 0.934, which was found to be 0.743 in unit 4.

When the frequency of the AC voltage is 30 Hz, the effective voltage ratio from the time when the application of the AC voltage is started to the time when one cycle has elapsed is 0.992 in the unit 1 and 0. It was found to be 947, 0.781 in unit 3 and 0.603 in unit 4. When the frequency of the AC voltage is 40 Hz, the effective voltage factor is 0.990 in unit 1, 0.930 in unit 2, 0.718 in unit 3, and 0.521 in unit 4. Was recognized as. When the frequency of the AC voltage is 50 Hz, the effective voltage factor is 0.987 in unit 1, 0.912 in unit 2, 0.659 in unit 3, and 0.455 in unit 4. Was recognized as.

Further, the time constant τ is 0.3 ms in the unit 1, 1.8 ms in the unit 2, 7.35 ms in the unit 3, and 14.7 ms in the unit 4. Was recognized.

FIG. 9 schematically shows a method of measuring the flicker rate of the dimming sheet 21N included in each unit. The flicker rate is an index defined by the American Lighting Engineering Association (IES) and is calculated by the following formula (3).
% F (flicker rate) = 100 × (AB) / (A + B)… Equation (3)
In the formula (3), A is the maximum value of the detected light amount, and B is the minimum value of the detected light amount.

As shown in FIG. 9, when measuring the flicker rate of the dimming sheet 21N, the illumination 41, the support plate 42, and the measuring instrument 43 are prepared. The support plate 42 is arranged on the illumination 41, and the dimming unit 11 to be measured is arranged on the support plate 42. Then, the measuring instrument 43 is placed in the dimming sheet 21N with the support plate 42 so that the center of the illumination 41 and the light receiving portion of the measuring instrument 43 face each other when viewed from the viewpoint facing the plane on which the dimming sheet 21N spreads. Make contact with the surface opposite to the surface in contact with.

In this test example, a DC LED light was used as the illumination 41. Further, a glass substrate having a thickness of 5 mm was used as the support plate 42. A flicker meter (multimedia display tester 3298F, manufactured by Yokogawa Electric Corporation) was used as the measuring instrument 43. It was also confirmed that the flicker rate of the DC LED light used as the illumination 41 was 0.0%. In this test example, in the region F shown in FIG. 7, that is, in the region of the short side of the dimming sheet 21N located near the short side having a large distance from the electrodes 22A and 22B, the dimming sheet 21N is used. The flicker rate was measured.

The measurement result of the flicker rate when the frequency of the AC voltage is 30 Hz is as shown in FIG. 10, and the measurement result of the flicker rate when the frequency of the AC voltage is 40 Hz is as shown in FIG. The measurement result of the flicker rate when the frequency of was 50 Hz was as shown in FIG. The effective value of the AC voltage was set to 50V.

Each of FIGS. 10 to 12 shows the relationship between the effective voltage rate of the dimming unit 11 and the measurement result of the flicker rate. In each figure, the result when a rectangular wave-shaped AC voltage is applied is shown by a white square, and the result when a sine wave-shaped AC voltage is applied is shown by a white diamond.

As shown in FIG. 10, the flicker rate when a rectangular wavy AC voltage is applied is 0.11% in the unit 1, 0.49% in the unit 2, and 2.31% in the unit 3. , Unit 4 was found to be 4.03%. The flicker rate when a sine-wave AC voltage is applied is 1.22% in unit 1, 1.23% in unit 2, 2.19% in unit 3, and 3.58 in unit 4. Was found to be%.

As shown in FIG. 11, the flicker rate when a rectangular wavy AC voltage is applied is 0.11% in the unit 1, 0.48% in the unit 2, and 2.15% in the unit 3. , Was found to be 2.74% in unit 4. The flicker rate when a sine-wave AC voltage is applied is 0.81% in unit 1, 0.89% in unit 2, 1.92% in unit 3, and 2.68 in unit 4. Was found to be%.

As shown in FIG. 12, the flicker rate when a rectangular AC voltage is applied is 0.10% in the unit 1, 0.43% in the unit 2, and 1.93% in the unit 3. , It was found to be 1.52% in unit 4. The flicker rate when a sine-wave AC voltage is applied is 0.58% in unit 1, 0.67% in unit 2, 1.61% in unit 3, and 1.62 in unit 4. Was found to be%.

As described above, when the effective voltage ratio of the dimming unit 11 is 0.9 or more, it is recognized that the flicker ratio is close to 1% or 1% or less. When the flicker rate is about 1%, the observer of the dimming sheet 21N cannot visually recognize that flicker is generated in the dimming sheet 21N. Further, it was found that the occurrence of flicker was suppressed in a wider frequency band when the AC voltage had a rectangular wave shape as compared with the case where the AC voltage had a sine wave shape.

[Test Example 2]
Test Example 2 will be described with reference to FIGS. 13 to 17.
FIG. 13 shows the planar structure of the dimming unit 11 used in Test Example 2.

As shown in FIG. 13, the dimming unit 11 includes a normal type dimming sheet 21N. The dimming sheet 21N has a rectangular shape. The dimming unit 11 includes four sets of electrode pairs.

The first electrode pair 22P1 and the third electrode pair 22P3 are located in pairs in the vicinity of different short sides of the dimming sheet 21N. Each electrode included in the first electrode pair 22P1 has a band shape extending along the short side. Each electrode included in the first electrode pair 22P1 is longer than each electrode included in the third electrode pair 22P3. The second electrode pair 22P2 and the fourth electrode pair 22P4 are located in pairs in the vicinity of different long sides of the dimming sheet 21N. Each electrode included in the second electrode pair 22P2 has a band shape extending along the long side. Each electrode included in the second electrode pair 22P2 is longer than each electrode included in the fourth electrode pair 22P4.

In the light control sheet 21N, a polymer-dispersed light control layer 33 was prepared, and the thickness of the light control layer 33 was 0.02 mm. Further, a PET film on which an ITO film is formed is prepared, and a first transparent electrode layer 31 supported by the first transparent base material 34 and a second transparent electrode layer supported by the second transparent base material 35 from the film are prepared. I got 32. The thickness of the ITO film was 150 nm, and the thickness of the PET film was 0.1 mm. In the dimming sheet 21N, the length LL of the long side was set to 1500 mm, and the length LS of the short side was set to 1000 mm.

Further, the first electrode pair 22P1 and the second electrode pair 22P2 were formed of copper tape. Further, the length LE1 of each electrode included in the first electrode pair 22P1 was set to 400 mm in the direction along the short side. Further, the length LE2 of each electrode included in the second electrode pair 22P2 was set to 600 mm in the direction along the long side.

On the other hand, the third electrode pair 22P3 and the fourth electrode pair 22P4 were formed by FPC. Further, the length LE3 of each electrode included in the third electrode pair 22P3 was set to 50 mm in the direction along the short side. In the third electrode pair 22P3, the distance DE3 between the center of each electrode and the end of the short side was set to 250 mm in the direction in which the short side was extended. Further, the length LE4 of each electrode included in the fourth electrode pair 22P4 was set to 50 mm in the direction along the long side. In the fourth electrode pair 22P4, the distance DE4 between the center of each electrode and the end of the long side was set to 375 mm in the direction in which the long side was extended.

In the dimming unit 11, it was found that the capacitance component C was 1.5 μF. On the other hand, the resistance component R when the first electrode pair 22P1 is used is 120Ω, the resistance component R when the second electrode pair 22P2 is used is 70Ω, and the resistance component R is 70Ω when the third electrode pair 22P3 is used. It was found that the resistance component R of the above was 350Ω, and the resistance component R when the fourth electrode pair 22P4 was used was 250Ω.

For the dimming unit 11, the voltage rise rate when each electrode pair was used was calculated. The result of calculating the voltage rise rate was as shown in FIG.
As shown in FIG. 14, it was found that the smaller the resistance value in the dimming unit 11, the steeper the curve of the voltage rise rate in the dimming unit 11. Note that FIG. 14 shows a curve of the voltage rise rate when the frequency of the AC voltage is 50 Hz.

When the frequency of the AC voltage is 30 Hz, the voltage rise rate at the time when one cycle elapses from the time when the application of the AC voltage is started is either the first electrode pair 22P1 or the fourth electrode pair 22P4. It was confirmed that it was 1.000 even if it was present. When the frequency of the AC voltage is 40 Hz, the voltage rise rate at the time when one cycle elapses from the time when the application of the AC voltage is started is the case where any of the first electrode pair 22P1 and the third electrode pair 22P3 is used. It was also 1.000, and it was confirmed that it was 0.999 when the fourth electrode pair 22P4 was used. When the frequency of the AC voltage is 50 Hz, the voltage rise rate at the time when one cycle elapses from the time when the application of the AC voltage is started is the case where any of the first electrode pair 22P1 and the third electrode pair 22P3 is used. It was also 1.000, and it was confirmed that it was 0.997 when the fourth electrode pair 22P4 was used.

When the frequency of the AC voltage is 30 Hz, the effective voltage ratio from the time when the application of the AC voltage is started to the time when one cycle has elapsed is 0.966 when the first electrode pair 22P1 is used. It was found to be 0.981 when the second electrode pair 22P2 was used. When the frequency of the AC voltage is 30 Hz, the effective voltage factor is 0.927 when the third electrode pair 22P3 is used, and 0.898 when the fourth electrode pair 22P4 is used. Was recognized.

When the frequency of the AC voltage is 40 Hz, the effective voltage factor is 0.955 when the first electrode pair 22P1 is used, and 0.975 when the second electrode pair 22P2 is used. It was found to be 0.904 when the 3-electrode pair 22P3 was used and 0.865 when the 4th electrode pair 22P4 was used. When the frequency of the AC voltage is 50 Hz, the effective voltage factor is 0.944 when the first electrode pair 22P1 is used and 0.968 when the second electrode pair 22P2 is used. It was found to be 0.880 when the 3-electrode pair 22P3 was used and 0.831 when the 4th electrode pair 22P4 was used.

Further, the time constant τ is 1.18 ms when the first electrode pair 22P1 is used, 0.69 ms when the second electrode pair 22P2 is used, and the third electrode pair 22P3 is used. It was found to be 2.45 ms when there was, and 3.43 ms when the 4th electrode pair 22P4 was used.

In Test Example 2, the flicker rate when each electrode pair was used was measured by using the same method as in Test Example 1. The flicker rate was measured in the region F (see FIG. 13) including the center of the dimming sheet 21N when viewed from the viewpoint facing the plane on which the dimming sheet 21N spreads.

The measurement result of the flicker rate when the frequency of the AC voltage is 30 Hz is as shown in FIG. 15, and the measurement result of the flicker rate when the frequency of the AC voltage is 40 Hz is as shown in FIG. The measurement result of the flicker rate when the frequency of is 50 Hz is as shown in FIG.

Each of FIGS. 15 to 17 shows the relationship between the effective voltage rate of the dimming unit 11 and the measurement result of the flicker rate. In each figure, the result when a rectangular wave-shaped AC voltage is applied is shown by a white square, and the result when a sine wave-shaped AC voltage is applied is shown by a white diamond.

As shown in FIG. 15, the flicker rate when a rectangular wave-shaped AC voltage is applied is 0.22% when the first electrode pair 22P1 is used, and 0 when the second electrode pair 22P2 is used. It was found to be 15%, 0.70% when the third electrode pair 22P3 was used, and 1.09% when the fourth electrode pair 22P4 was used. The flicker rate when a sine-wave AC voltage is applied is 1.30% when the first electrode pair 22P1 is used, 1.29% when the second electrode pair 22P2 is used, and the third. It was found to be 1.46% when the electrode pair 22P3 was used and 1.60% when the fourth electrode pair 22P4 was used.

As shown in FIG. 16, the flicker rate when a rectangular wave-shaped AC voltage is applied is 0.20% when the first electrode pair 22P1 is used, and 0 when the second electrode pair 22P2 is used. It was found to be 16%, 0.68% when the third electrode pair 22P3 was used, and 1.01% when the fourth electrode pair 22P4 was used. The flicker rate when a sine-wave AC voltage is applied is 1.04% when the first electrode pair 22P1 is used, 1.01% when the second electrode pair 22P2 is used, and the third. It was found to be 1.28% when the electrode pair 22P3 was used and 1.34% when the fourth electrode pair 22P4 was used.

As shown in FIG. 17, the flicker rate when a rectangular wavy AC voltage is applied is 0.19% when the first electrode pair 22P1 is used, and is 0 when the second electrode pair 22P2 is used. It was found to be 14%, 0.65% when the third electrode pair 22P3 was used, and 0.92% when the fourth electrode pair 22P4 was used. The flicker rate when a sine-wave AC voltage is applied is 0.84% when the first electrode pair 22P1 is used, 0.76% when the second electrode pair 22P2 is used, and the third electrode pair 22P2. It was found to be 1.04% when the electrode pair 22P3 was used and 1.16% when the fourth electrode pair 22P4 was used.

As described above, as in Test Example 1, when the effective voltage rate of the dimming unit 11 is 0.9 or more in Test Example 2, it is recognized that the flicker rate is close to 1% or 1% or less. Was done. Further, it was found that the occurrence of flicker was suppressed in a wider frequency band when the AC voltage had a rectangular wave shape as compared with the case where the AC voltage had a sine wave shape.

Further, the flicker rate is lower when the second electrode pair 22P2 is used as compared with the case where the first electrode pair 22P1 is used, and the flicker rate is lower when the second electrode pair 22P2 is used, and the fourth electrode pair is compared with the case where the third electrode pair 22P3 is used. It was found that the flicker rate was low when 22P4 was used. In the first electrode pair 22P1, the distance between the pair of electrodes is smaller than that in the second electrode pair 22P2, so that the resistance component R of the dimming unit 11 is small, and it can be said that the flicker rate is lowered. Further, in the third electrode pair 22P3, since the distance between the pair of electrodes is smaller than that in the fourth electrode pair 22P4, the resistance component R of the dimming unit 11 is small, and as a result, the flicker rate is lowered. I can say.

As described above, according to one embodiment of the dimming device, the following effects can be obtained.
(1) When the effective voltage ratio of the dimming unit 11 is 0.9 or more, among the AC voltages applied between the pair of transparent electrode layers 31 and 32, the liquid crystal molecules included in the dimming layer 33 are driven. The proportion of contribution can be increased, thereby increasing the responsiveness of the liquid crystal molecules. As a result, it is possible to suppress the occurrence of flicker in the dimming sheets 21N and 21R.

(2) The dimming unit 11 has the responsiveness of the liquid crystal molecules contained in the dimming layer 33 when the frequency of the AC voltage applied between the pair of transparent electrode layers 31 and 32 is 30 Hz or more and 60 Hz or less. Has a time constant τ small enough to be able to increase. Therefore, it is possible to suppress the occurrence of flicker in the dimming sheets 21N and 21R.

(3) By applying an AC voltage having a rectangular wave shape between the pair of transparent electrode layers 31 and 32, it is possible to suppress the formation of a transient state in the orientation of the liquid crystal molecules, whereby the dimming sheet is suppressed. The occurrence of flicker can be suppressed in 21N and 21R.

(4) By configuring the dimming device 10 so as to satisfy the above equation, it contributes to driving the liquid crystal molecules contained in the dimming layer 33 among the AC voltages applied between the pair of transparent electrode layers 31 and 32. It is possible to increase the responsiveness of the liquid crystal molecule. As a result, it is possible to suppress the occurrence of flicker in the dimming sheets 21N and 21R.

The above-described embodiment can be modified and implemented as follows.
[AC voltage]
The AC voltage applied by the drive unit 12 between the first transparent electrode layer 31 and the second transparent electrode layer 32 may have a sine wave shape or a serrated shape. Even in these cases, if the effective voltage ratio is 0.9 or more, the effect according to (1) described above can be obtained. Alternatively, when the time constant τ is equal to or less than the value calculated by the above-mentioned linear function, the effect according to the above-mentioned (2) can be obtained.

10 ... Dimming device 11 ... Dimming unit 12 ... Drive unit 21N, 21R ... Dimming sheet 22A ... First electrode 22B ... Second electrode 23A ... First wiring 23B ... Second wiring 31 ... First transparent electrode layer 32 ... 2nd transparent electrode layer 33 ... Dimming layer 34 ... 1st transparent base material 35 ... 2nd transparent base material 36 ... 1st alignment film 37 ... 2nd alignment film

Claims (8)

A dimming sheet including a first transparent electrode layer, a second transparent electrode layer, and a dimming layer sandwiched between the first transparent electrode layer and the second transparent electrode layer and containing a plurality of liquid crystal molecules. Prepare,
The effective voltage ratio from the time when the application of the AC voltage between the first transparent electrode layer and the second transparent electrode layer is started to the time when one cycle elapses is 0.9 or more, and the effective voltage ratio is , The ratio of the sum of the reached values of the AC voltage (SE) to the sum of the effective values of the AC voltage (SR) from the time when the application of the AC voltage is started to the time when the one cycle elapses (SE / SR). The dimming unit that is. A dimming sheet including a first transparent electrode layer, a second transparent electrode layer, and a dimming layer sandwiched between the first transparent electrode layer and the second transparent electrode layer and containing a plurality of liquid crystal molecules. Prepare,
When the AC voltage applied between the first transparent electrode layer and the second transparent electrode layer has a frequency of 30 Hz or more and 60 Hz or less, and is a time constant (milliseconds) or less calculated by the following function. It has a constant y = 101.9919 × (1 / x)
Dimming unit. The dimming unit according to claim 1 or 2,
A dimming device including a drive unit for applying the AC voltage between the first transparent electrode layer and the second transparent electrode layer. The dimming device according to claim 3, wherein the driving unit applies the AC voltage having a rectangular wavy shape between the first transparent electrode layer and the second transparent electrode layer. A drive unit that outputs a square wave voltage signal,
A dimming layer sandwiched between a first transparent electrode layer, a second transparent electrode layer, the first transparent electrode layer and the second transparent electrode layer, and containing a plurality of liquid crystal molecules is provided, and is applied by the driving unit. Equipped with a dimming unit, including a dimming sheet, whose haze value changes according to the voltage applied.
The response function f (t) showing the relationship between the period T of the voltage signal, the DC voltage corresponding to the amplitude of the square wave, and the voltage between the transparent electrodes in the dimming unit when the DC voltage is applied. ) And so that the following equation holds.

Dimming device. A drive unit that outputs a square wave voltage signal,
A dimming layer sandwiched between a first transparent electrode layer, a second transparent electrode layer, the first transparent electrode layer and the second transparent electrode layer, and containing a plurality of liquid crystal molecules is provided, and is applied by the driving unit. It is equipped with a dimming unit including a dimming sheet whose haze value changes according to the voltage to be applied.
Using the period T of the voltage signal and the time constant τ of the dimming unit, the following equation is established.

Dimming device. A dimming unit provided with a dimming sheet sandwiched between a first transparent electrode layer, a second transparent electrode layer, and a first transparent electrode layer and a second transparent electrode layer and having a dimming layer containing a plurality of liquid crystal molecules. However, it includes applying an AC voltage between the first transparent electrode layer and the second transparent electrode layer.
Applying an AC voltage means that the first transparent electrode layer and the second transparent electrode layer have an effective voltage ratio of 0.9 or more from the time when the application of the AC voltage is started to the time when one cycle elapses. The effective voltage ratio includes the application of an AC voltage in between, and the effective voltage ratio is the value reached by the AC voltage with respect to the sum of the effective values of the AC voltage (SR) from the time when the application of the AC voltage is started to the time when one cycle elapses. A method of driving a dimming unit, which is a total (SE) ratio (SE / SR). A dimming unit provided with a dimming sheet sandwiched between a first transparent electrode layer, a second transparent electrode layer, and a first transparent electrode layer and a second transparent electrode layer and having a dimming layer containing a plurality of liquid crystal molecules. However, it includes applying an AC voltage between the first transparent electrode layer and the second transparent electrode layer.
Applying an AC voltage applies an AC voltage having a frequency of 30 Hz or more and 60 Hz or less to the first transparent electrode layer and the second transparent electrode so that the time constant of the dimming sheet is a value calculated by the following function. Apply between layers y = 101.9919 × (1 / x)
How to drive the dimming unit.

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