JP7310309B2 - Light control device and method for driving light control sheet - Google Patents

Description

The present invention relates to a light control device having a light control sheet and a method for driving the light control sheet.

The light control sheet includes a liquid crystal composition sandwiched between a pair of transparent electrodes. The liquid crystal composition changes the light control sheet between transparent and opaque in response to a change in voltage across the transparent electrodes. A drive device for a light control sheet applies an AC voltage between transparent electrodes in order to suppress segregation of impurity ions and the like, thereby extending the life of the light control layer (see, for example, Patent Document 1).

Types of light control sheets are classified into normal type and reverse type. In the normal type, the light control layer is opaque when not energized, and transparent when energized. The normal type is suitable for applications such as screens that frequently require light shielding properties. In the reverse type, the light control layer is transparent when not energized, and opaque when energized (see, for example, Patent Document 2). The reverse type is suitable for application to building materials and the like that require transparency and safety in emergencies.

JP 2018-091986 A JP-A-2000-321562

In recent years, the application range of the light control sheet has been steadily expanding, and along with this, the use of the light control sheet under low temperatures such as in cold regions is being studied. In addition, when the light control sheet is used at low temperatures, a new problem arises in that the orientation of the liquid crystal molecules is difficult to follow changes in voltage.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a light control device and a method of driving a light control sheet that can lower the lower limit of the temperature at which the light control sheet can be driven.

A light control device for solving the above problems includes a light control sheet and a driving device that drives the light control sheet. The light control sheet includes a first transparent electrode having a first terminal, a second transparent electrode having a plurality of second terminals, and a liquid crystal positioned between the first transparent electrode and the second transparent electrode. a molecule; The drive device applies a heating voltage between the second terminal and the first terminal and the and applying a drive voltage to and from the second terminal.

A light control sheet driving method for solving the above problems is a light control sheet driving method for driving a light control sheet, wherein the light control sheet includes a first transparent electrode having a first terminal, a plurality of and liquid crystal molecules positioned between the first transparent electrode and the second transparent electrode, wherein the liquid crystal molecules are heated to the second transparent electrode. Simultaneously applying a heating voltage between the second terminals and applying a driving voltage between the first terminal and the second terminal so as to change the polarization direction of the liquid crystal molecules depending on the state; During the period of simultaneous application, the polarity of the heating voltage is reversed.

According to each of the above configurations, the application of voltage by the driving device can heat the liquid crystal molecules, and the polarization direction of the liquid crystal molecules can be changed using the liquid crystal molecules in a heated state. As a result, even if the light control sheet is placed at a low temperature such that the polarization direction of the liquid crystal molecules does not follow the voltage change, the application of voltage by the driving device can change the polarization direction of the liquid crystal molecules. Therefore, the lower limit of the temperature at which the light control sheet can be driven is lowered.
In the light control device described above, the driving section may reverse the polarity of the heating voltage during a period in which the application of the driving voltage and the application of the heating voltage are performed simultaneously.

When a heating voltage is applied to the second transparent electrode, a potential difference corresponding to the heating voltage is generated in the plane of the second transparent electrode. For example, when a heating voltage is applied between two second terminals, a relatively high level is input to one second terminal and a relatively low level is input to the other second terminal. As a result, a potential difference corresponding to the difference between the high level and the low level is generated in the plane of the second transparent electrode.

If a potential difference is generated in the plane of the second transparent electrode while a driving voltage is applied between the two transparent electrodes, the voltage applied to the liquid crystal molecules is also the same throughout the period in which the driving voltage is applied. In addition, variations corresponding to the heating voltage continue to occur within the surface of the light control sheet. As a result, segregation of impurity ions or the like is more likely to occur within the plane of the light control sheet than when the voltage applied to the liquid crystal molecules is uniform within the plane of the light control sheet.

In this respect, according to the above configuration, the polarity of the heating voltage is reversed between the second terminals during the period in which the application of the drive voltage and the application of the heating voltage are performed simultaneously. As a result, it is possible to suppress the occurrence of a potential difference that causes segregation of impurity ions and the like over the entire period in which the application of the drive voltage and the application of the heating voltage are performed simultaneously. As a result, the segregation of impurity ions and the like that may occur due to the potential difference between the second terminals is canceled by the polarity reversal of the heating voltage.

In the light control device described above, the driving section may reverse the polarity of the heating voltage every predetermined period. According to this configuration, the polarity of the potential difference that causes segregation of impurity ions or the like is reversed every predetermined period, so that the effect of suppressing the segregation of impurity ions or the like can be obtained with high accuracy.

In the light control device described above, the drive unit may switch between application of the heating voltage and application of the drive voltage. According to this configuration, the application of the heating voltage and the application of the drive voltage are performed separately, so that the power consumption due to the application of the heating voltage is suppressed during the period in which the light control sheet does not need to be heated.

In the light control device described above, the driving section applies the heating voltage between the second terminals prior to application of the driving voltage until a predetermined time has elapsed after the power is turned on to the driving device. may

Application of a driving voltage at a low temperature in which the polarization direction of the liquid crystal molecules does not follow changes in the driving voltage unnecessarily increases the power consumption of the light control device and delays raising the temperature of the liquid crystal molecules. . In this respect, according to the above configuration, the liquid crystal molecules are heated for a predetermined time prior to changing the polarization direction of the liquid crystal molecules. Therefore, it is possible to suppress the application of the driving voltage at a low temperature such that the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage.

In the light control device, the temperature of the light control sheet when the polarization direction of the liquid crystal molecules follows the driving voltage is a predetermined drivable temperature, and the drive section measures the temperature of the light control sheet. a measuring unit, wherein application of the heating voltage is allowed and application of the driving voltage is prohibited when the measured value of the measuring unit is lower than the drivable temperature, and the measured value of the measuring unit is the drivable temperature When it is at temperature, the application of the heating voltage may be prohibited and the application of the drive voltage may be permitted.

According to the above configuration, when the temperature of the light control sheet is lower than the drivable temperature, the application of the drive voltage is prohibited and the application of the heating voltage is allowed. Heating is performed when the change cannot be followed, that is, when the liquid crystal molecules require heating. In addition, when the temperature of the light control sheet is at the drivable temperature, the application of the heating voltage is prohibited and the application of the drive voltage is allowed, so that the polarization direction of the liquid crystal molecules can follow the change in the drive voltage. Sometimes, ie when the liquid crystal molecules do not require heating, the heating can be inhibited.

According to the light control device of the present invention, the lower limit of the temperature at which the light control sheet can be driven can be lowered.

The block diagram which shows the structure of the light control sheet with which 1st Embodiment of a light control device is provided. Sectional drawing which shows the cross-sectional structure of a normal type|mold light control sheet. Sectional drawing which shows the cross-sectional structure of a reverse type light control sheet. The block diagram which shows the electrical structure in 1st Embodiment of a light control apparatus. The circuit diagram which shows the structure of the drive circuit with which a light control device is provided. The timing chart which shows an example of the flow of the heat processing which a light control apparatus performs. The block diagram which shows the electrical structure in the light control apparatus of the 1st modification. The block diagram which shows the electrical structure in the light control apparatus of the 2nd modification. The block diagram which shows a part of electrical structure with which 2nd Embodiment of a light control device is provided. The timing chart which shows an example of the flow of the heat processing which a light control apparatus performs. The graph which shows transition of the voltage level in the heat processing which a light control apparatus performs. The block diagram which shows the structure of the light control sheet with which the light control apparatus of a modification is provided.

(First embodiment)
A first embodiment of a light control device will be described with reference to FIGS. 1 to 6. FIG. Hereinafter, the layer structure of the light control sheet, the electrical structure of the light control device, the heating process performed by the light control device, and the driving process performed by the light control device will be described in this order.

The light control device of the first embodiment is an example in which both the first transparent electrode and the second transparent electrode included in the light control sheet are used as heat sources for the liquid crystal molecules, and the polarization direction of the liquid crystal molecules is not changed. This is an example of heating liquid crystal molecules for a period of time.

[Light control sheet 10]
FIG. 1 is an exploded perspective view showing the light control sheet 10 disassembled into three functional layers. Each functional layer may have a single layer structure or a laminated multilayer structure.

The light control sheet 10 is attached, for example, to a window of a mobile object such as a vehicle or an aircraft. For example, the light control sheet 10 can be attached to windows of various buildings such as houses, stations, and airports, partitions installed in offices, show windows installed in stores, and moving objects such as automatic doors. good.

The shape of the light control sheet 10 is, for example, planar. The shape of the light control sheet 10 may be a curved surface having a curvature in two-dimensional directions, or a curved surface having a curvature in three-dimensional directions. The outer shape of the light control sheet 10 may be the same as the outer shape of the support such as a glass plate or a transparent resin plate, or may be different from the outer shape of the support.

The type of the light control sheet 10 is either a normal type or a reverse type.
The normal type light control sheet 10 has a low light transmittance when the light control sheet 10 is energized, and has a high light transmittance when the light control sheet 10 is not energized. The normal type light control sheet 10 is transparent when the light control sheet 10 is energized, and opaque when the light control sheet 10 is not energized.

The reverse type light control sheet 10 has a high light transmittance when the light control sheet 10 is energized, and has a low light transmittance when the light control sheet 10 is not energized. The reverse type light control sheet 10 is opaque when the light control sheet 10 is energized and transparent when the light control sheet 10 is not energized.
The transparent may be colored transparent or colorless transparent.

Transparency is a state in which the presence or absence of an object can be visually recognized through the light control sheet 10 . Opaque is a state in which the presence or absence of an object through the light control sheet 10 cannot be visually recognized. Transparency may be a state in which the shape and type of an object can be visually recognized through the light control sheet 10 . Opaque may be a state in which the shape or type of an object cannot be visually recognized through the light control sheet 10 .

The light control sheet 10 has a first transparent electrode 11 and a second transparent electrode 12 . Each transparent electrode 11, 12 is supported by a separate transparent body. A transparent body that supports the transparent electrodes 11 and 12 is, for example, a transparent resin film, a transparent resin plate, a transparent glass sheet, or a transparent glass plate.

The light control sheet 10 has a light control layer 13 . The light control layer 13 is positioned between the first transparent electrode 11 and the second transparent electrode 12 . The direction in which the first transparent electrode 11 , the light control layer 13 , and the second transparent electrode 12 are stacked is the stacking direction of the light control sheet 10 .

Each transparent electrode 11, 12 has visible light transparency. Visible light transmission allows visual recognition of objects through the light control sheet 10 . Materials constituting the transparent electrodes 11 and 12 are selected from the group consisting of, for example, indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, and poly(3,4-ethylenedioxythiophene). Either one.

The light control layer 13 contains a liquid crystal composition. The dimming layer 13 is regarded as a parallel circuit of capacitive and resistive components. Examples of liquid crystal molecules contained in the liquid crystal composition include Schiff base, azo, azoxy, biphenyl, terphenyl, benzoate, tolan, pyrimidine, cyclohexanecarboxylate, phenylcyclohexane, It is one kind selected from the group consisting of dioxane series.

The retention type of the liquid crystal composition is one selected from the group consisting of polymer network type, polymer dispersion type, and capsule type. The polymer network type has a three-dimensional mesh-like polymer network, and retains the liquid crystal composition in interconnected mesh-like voids. The polymer-dispersed type has a large number of isolated voids in the polymer layer, and holds the liquid crystal composition in the voids dispersed in the polymer layer. The capsule type retains a liquid crystal composition having a capsule shape in a polymer layer.

The first transparent electrode 11 has a pair of first terminals 11P1 and 11P2. The pair of first terminals 11P1 and 11P2 are arranged at positions facing each other with the center of the first transparent electrode 11 interposed therebetween. When the first transparent electrode 11 has a rectangular shape, one first terminal 11P1 extends along the upper side of the first transparent electrode 11, for example. The other first terminal 11P2 extends along the lower side of the first transparent electrode 11. As shown in FIG.

The second transparent electrode 12 has a pair of second terminals 12P1 and 12P2. The pair of second terminals 12P1 and 12P2 are arranged at positions facing each other with the center of the second transparent electrode 12 interposed therebetween. The pair of second terminals 12P1 and 12P2 are arranged at positions that do not overlap the pair of first terminals 11P1 and 11P2 in the stacking direction. When the second transparent electrode 12 has a rectangular shape, one second terminal 12P1 extends along the right side of the second transparent electrode 12, for example. The other second terminal 12P2 extends along the left side of the second transparent electrode 12. As shown in FIG.

FIG. 2 shows an example of the layered structure of the normal type light control sheet 10 .
As shown in FIG. 2 , the normal type light control sheet 10 includes a first transparent electrode 11 , a second transparent electrode 12 and a light control layer 13 . The first transparent electrode 11 and the second transparent electrode 12 are electrically connected to a switching circuit 33, which is an example of a switching section.

When the switching circuit 33 applies a drive voltage to the normal type light control sheet 10, the first terminals 11P1 and 11P2 of the first transparent electrode 11 are applied with a first output level, which is the voltage level at the output terminal of the switching circuit 33. SIGD1 is input. A second output level SIGD2, which is the voltage level at the other output terminal of the switching circuit 33, is input to the second terminals 12P1 and 12P2 of the second transparent electrode 12. FIG.

The light modulating layer 13 receives a drive voltage applied between the two transparent electrodes 11 and 12 and changes the polarization direction of the liquid crystal molecules. The drive voltage is a voltage that changes the polarization direction of the liquid crystal molecules. The polarization direction of each liquid crystal molecule includes a state aligned with the polarization directions of other liquid crystal molecules or a disordered state. A change in the polarization direction changes the degree of scattering, absorption, and transmission of visible light entering the light modulating layer 13 .

When the first output level SIGD1 and the second output level SIGD2 are mutually equal voltage levels, for example, when the two transparent electrodes 11 and 12 are connected to the ground level, the normal type light control sheet 10 is a liquid crystal Disorder the polarization directions of the molecules. When the polarization directions of the liquid crystal molecules are disordered, the light transmittance of the normal type light control sheet 10 is relatively low.

When the potential difference between the first output level SIGD1 and the second output level SIGD2 is a predetermined value or more, that is, when the voltage between the two transparent electrodes 11 and 12 is a predetermined value or more, the normal type light control sheet 10 , the polarization directions of the liquid crystal molecules are aligned so that the light modulating layer 13 transmits visible light. When the polarization directions of the liquid crystal molecules are aligned, the light transmittance of the normal type light control sheet 10 is relatively high.

FIG. 3 shows an example of the layered structure of the reverse type light control sheet 10 .
As shown in FIG. 3 , the reverse type light control sheet 10 includes a first transparent electrode 11 , a second transparent electrode 12 , a first alignment film 14 , a second alignment film 15 , and a light control layer 13 .
The dimming layer 13 is positioned between the first alignment film 14 and the second alignment film 15 . The first alignment film 14 is located between the light control layer 13 and the first transparent electrode 11 and is in contact with the light control layer 13 . The second alignment film 15 is located between the light control layer 13 and the second transparent electrode 12 and is in contact with the light control layer 13 .

Materials constituting the first alignment film 14 and the second alignment film 15 are, for example, organic compounds such as polyimide, polyamide, polyvinyl alcohol, and cyanide compounds, inorganic compounds such as silicone, silicon oxide, and zirconium oxide, or , are composed of mixtures of these.

The alignment film 14 and the second alignment film 15 are, for example, vertical alignment films or horizontal alignment films. The vertical alignment film aligns the polarization direction of the liquid crystal molecules so that it is perpendicular to the electrode surface of the first transparent electrode 11 and the electrode surface of the second transparent electrode 12 . The horizontal alignment film aligns the polarization direction of the liquid crystal molecules so that the electrode surface of the first transparent electrode 11 and the electrode surface of the second transparent electrode 12 are substantially parallel.

When the switching circuit 33 applies a driving voltage to the reverse type light control sheet 10, the first output level SIGD1 is applied to the first terminals 11P1 and 11P2 of the first transparent electrodes 11, as in the normal type light control sheet 10. A second output level SIGD2 is input to the second terminals 12P1 and 12P2 of the second transparent electrode 12 .

When the first output level SIGD1 and the second output level SIGD2 are voltage levels equal to each other, for example, when the two transparent electrodes 11 and 12 are connected to the ground level, the reverse type light control sheet 10 provides light control. The alignment films 14 and 15 align the polarization directions of the liquid crystal molecules so that the optical layer 13 transmits visible light. When the polarization directions of the liquid crystal molecules are aligned, the light transmittance of the reverse type light control sheet 10 is relatively high.

When the potential difference between the first output level SIGD1 and the second output level SIGD2 is a predetermined value or more, that is, when the voltage between the two transparent electrodes 11 and 12 is a predetermined value or more, the reverse type light control sheet 10 , the polarization directions of the liquid crystal molecules are aligned so that the light modulating layer 13 does not transmit visible light. When the polarization directions of the liquid crystal molecules are aligned, the light transmittance of the reverse type light control sheet 10 is relatively low.

[Light control sheet driving device]
FIG. 4 is a block diagram functionally showing the configuration of the driving device 20. As shown in FIG.
As shown in FIG. 4, the drive device 20 includes a protection circuit 22, a booster circuit 23, a drive circuit 24, a voltage generation circuit 25, and a timing control circuit .
The protection circuit 22 is connected to the power supply 21 and the booster circuit 23 . The protection circuit 22 inputs the DC constant voltage output by the power supply 21 to the booster circuit 23 . The protection circuit 22 is connected to the power supply 21 and the voltage generation circuit 25 . The protection circuit 22 inputs the DC constant voltage output by the power supply 21 to the voltage generation circuit 25 . When the output current of the power supply 21 is equal to or higher than a predetermined value, the protection circuit 22 blows the fuses to disconnect the power supply 21 and the booster circuit 23 and the power supply 21 and the voltage generation circuit 25 . The fuse provided in the protection circuit 22 has a large blowing current so that it will not be blown by normal current ripple.

The booster circuit 23 generates a voltage for generating a drive voltage from the DC constant voltage input by the protection circuit 22 . A high drive level VH for generating a drive voltage is, for example, 50V. The drive voltage has a waveform in which the high drive level VH and the reference level V0 are alternately repeated. The high drive level VH is a magnitude that allows the orientation of the liquid crystal molecules to be changed by applying a drive voltage under normal temperature and normal pressure. In addition, normal temperature is 20 degreeC and normal pressure is 1 atmosphere.

[Drive voltage]
The drive circuit 24 generates a drive voltage using the DC constant voltage input by the booster circuit 23 . Drive circuit 24 inputs the generated drive voltage to switching circuit 33 . The drive circuit 24 outputs the generated drive voltage as a first output level SIGD1 and a second output level SIGD2. In the drive voltage, the first output level SIGD1 and the second output level SIGD2 are different voltage levels.

Specifically, when the drive circuit 24 outputs the drive voltage, the first output level SIGD1 alternates between the high drive level VH and the reference level V0. The reference level V0 is a level that serves as a reference for various potentials, and is, for example, a ground level. Also, when the drive circuit 24 outputs the drive voltage, the second output level SIGD2 also switches alternately between the high drive level VH and the reference level V0.

The voltage generation circuit 25 is connected with the protection circuit 22 . The voltage generation circuit 25 generates a voltage level for driving the timing control circuit 26 from the DC constant voltage output by the protection circuit 22 and inputs the generated voltage level to the timing control circuit 26 .

FIG. 5 is a circuit diagram showing an example of the configuration of the drive circuit 24. As shown in FIG.
As shown in FIG. 5, the drive circuit 24 comprises a full bridge circuit consisting of a first switch Q1, a second switch Q2, a third switch Q3 and a fourth switch Q4. The first switch Q1 is a p-channel transistor. The second switch Q2 is an n-channel transistor. The first switch Q1 and the second switch Q2 form a CMOS transistor. Also, the third switch Q3 is a p-channel transistor. The fourth switch Q4 is an n-channel transistor. The third switch Q3 and the fourth switch Q4 constitute a CMOS transistor.

The first switch Q1 and the second switch Q2 are connected in series. The third switch Q3 and the fourth switch Q4 are connected in series. The series-connected first switch Q1 and second switch Q2, and the series-connected third switch Q3 and fourth switch Q4 are connected in parallel. A connecting portion between the first switch Q1 and the second switch Q2 is connected to the output end of the first output level SIGD1. A connecting portion between the third switch Q3 and the fourth switch Q4 is connected to the output end of the second output level SIGD2. The timing control circuit 26 controls the ON period of each switch Q1, Q2, Q3, Q4 provided in the full bridge circuit.

The timing control circuit 26 has an arithmetic processing unit and a memory. The timing control circuit 26 is not limited to processing all of the various processes by software. For example, the timing control circuit 26 may comprise dedicated hardware (application specific integrated circuit: ASIC) that performs at least part of the various processes. The timing control circuit 26 is configured as a circuit including one or more dedicated hardware circuits such as ASICs, one or more processors (microcomputers) that operate according to computer programs (software), or combinations thereof. good too.

An example will be described below in which the timing control circuit 26 stores a drive program in a readable medium, reads out and executes the drive program stored in the readable medium, and generates a drive voltage.

The timing control circuit 26 simultaneously inputs a signal for turning on/off the first switch Q1 and a signal for turning on/off the fourth switch Q4 to each of the switches Q1 and Q4. The timing control circuit 26 simultaneously inputs a signal for turning on/off the second switch Q2 and a signal for turning on/off the third switch Q3 to each of the switches Q2 and Q3.

The timing control circuit 26 sets dead time for the drive circuit 24 . The dead time is a period for preventing through current from flowing between the high drive level VH and the reference level V0. When the timing control circuit 26 alternately switches between the high drive level VH and the reference level V0, it sets, for example, a period during which all the switches Q1, Q2, Q3, and Q4 are simultaneously turned off as a dead time.

Note that the timing control circuit 26 may change the pulse width of the drive voltage, which is a repetition of voltage pulses, by controlling the ON periods of the switches Q1, Q2, Q3, and Q4, for example. Changing the pulse width changes the effective value of the voltage applied to the light-modulating layer 13 and multi-gradates the visible light transmittance of the light-modulating layer 13 . The timing control circuit 26 may determine the gradation value of the visible light transmittance of the light control sheet 10 based on the operation signal input from the input section 27 . The operation signal input from the input unit 27 is generated, for example, by pressing an operation button for increasing or decreasing the visible light transmittance one step at a time, or an operation for making the light control sheet 10 transparent or opaque. Generated by pressing a button.

[Heating voltage]
Returning to FIG. 4 , the driving device 20 includes a timer circuit 31 , a heater power supply 32 and a switching circuit 33 . The drive circuit 24, the timing control circuit 26, the timer circuit 31, the heater power supply 32, and the switching circuit 33 are examples of the drive section.

Timer circuit 31 is connected to power supply 21 and switching circuit 33 . The timer circuit 31 receives the DC constant voltage input from the power supply 21 and measures the elapsed time after the driving device 20 is powered on. The driving device 20 is powered on, for example, when an operation signal for activating the light control device is input from the input unit 27 .

The timer circuit 31 generates a switching signal SIGS and inputs the generated switching signal SIGS to the switching circuit 33 . The timer circuit 31 generates the switching signal SIGS when the elapsed time T0 measured by the timer circuit 31 exceeds the heating time TH, which is a predetermined time.

The heating time TH is the time for heating the liquid crystal molecules contained in the liquid crystal composition, and is the time for causing the polarization direction of the liquid crystal molecules to follow the drive voltage. The heating time TH raises the temperature of the light control sheet 10 from, for example, the lower limit temperature at which the light control device can be used to the lower limit temperature at which the liquid crystal molecules can change the polarization direction by applying a driving voltage. It's time for The heating time TH is set based on the results of pre-implemented tests and the like.

Heater power supply 32 is connected to power supply 21 and switching circuit 33 . The heater power supply 32 receives the DC constant voltage input from the power supply 21 and generates a heating voltage for causing the first transparent electrode 11 and the second transparent electrode 12 to generate heat. The heating voltage is a constant DC voltage and is the difference between the high level VMH and the low level VML. The heater power supply 32 inputs the generated high level VMH and low level VML to the switching circuit 33 . A high level VMH is, for example, 10V and a low level VML is, for example, -10V.

The switching circuit 33 is connected to the first terminals 11P1 and 11P2 of the first transparent electrode 11 and the second terminals 12P1 and 12P2 of the second transparent electrode 12 . The switching circuit 33 has a standby state, a driving state, and a heating state.

The switching circuit 33 in the standby state inputs the ground level to the first terminals 11P1 and 11P2 and the second terminals 12P1 and 12P2.
The heating state switching circuit 33 inputs the high level VMH to the first terminal 11P1 and the second terminal 12P1, and inputs the low level VML to the first terminal 11P2 and the second terminal 12P2. That is, the heating state switching circuit 33 applies a heating voltage to each of the transparent electrodes 11 and 12 .

The driving state switching circuit 33 inputs the first output level SIGD1 to the first terminals 11P1 and 11P2, and inputs the second output level SIGD2 to the second terminals 12P1 and 12P2. That is, the driving state switching circuit 33 applies a driving voltage between the transparent electrodes 11 and 12 .

Switching circuit 33 continues the standby state until drive device 20 is powered on. The switching circuit 33 transitions from the standby state to the heating state when the driving device 20 is powered on. The switching circuit 33 continues the heating state until the timer circuit 31 receives the switching signal SIGS after the driving device 20 is powered on. The switching circuit 33 transitions from the heating state to the driving state when the switching signal SIGS is input from the timer circuit 31 .

[Drive method]
FIG. 6 is a timing chart showing the flow of heat treatment performed by the driving device 20. As shown in FIG. FIG. 6 shows transitions of the states of the switches Q1, Q2, Q3, Q4, the first output level SIGD1, the second output level SIGD2, the voltage levels of the first terminals 11P1, 11P2, and the voltage levels of the second terminals 12P1, 12P2. indicates

As shown in FIG. 6, when the driving device 20 is powered on at timing t0, the timer circuit 31 starts measuring the elapsed time T0. Heater power supply 32 inputs high level VMH and low level VML to switching circuit 33 . The switching circuit 33 transitions from the standby state to the heating state, inputs the high level VMH to the first terminal 11P1, and inputs the low level VML to the first terminal 11P2. As a result, the first transparent electrode 11 begins to generate heat, and the liquid crystal composition in the light control layer 13 begins to be heated by the first transparent electrode 11 . Also, the switching circuit 33 inputs the high level VMH to the second terminal 12P1 and inputs the low level VML to the second terminal 12P2. As a result, the second transparent electrode 12 begins to generate heat, and the second transparent electrode 12 begins to heat the liquid crystal composition of the light control layer 13 .

Next, from timing t1 to timing t2, the timing control circuit 26 outputs a signal for turning off the first switch Q1 and the fourth switch Q4 and a signal for turning on the second switch Q2 and the third switch Q3. , are input to the drive circuit 24 . As a result, the drive circuit 24 connects the reference level V0 input by the booster circuit 23 and the output end of the first output level SIGD1. Further, the drive circuit 24 connects the high drive level VH input by the booster circuit 23 and the output end of the second output level SIGD2.

Next, from timing t2 to timing t3, the timing control circuit 26 inputs to the driving circuit 24 a signal for turning off the second switch Q2 and the third switch Q3. During this time, the timing control circuit 26 continues to input signals to the driving circuit 24 to turn off the first switch Q1 and the fourth switch Q4. That is, the timing control circuit 26 causes the drive circuit 24 to simultaneously turn off all the switches Q1, Q2, Q3, Q4. As a result, the timing control circuit 26 prevents through current from flowing between the reference level V0 and the high drive level VH through the on-state switches Q1, Q2, Q3, and Q4.

Next, from timing t3 to timing t4, the timing control circuit 26 outputs a signal for turning on the first switch Q1 and the fourth switch Q4 and a signal for turning off the second switch Q2 and the third switch Q3. , are input to the drive circuit 24 . As a result, the drive circuit 24 connects the high drive level VH input by the booster circuit 23 and the output end of the first output level SIGD1. Further, the drive circuit 24 connects the reference level V0 input by the booster circuit 23 and the output end of the second output level SIGD2.

Next, from timing t4 to timing t5, the timing control circuit 26 inputs to the driving circuit 24 a signal for turning off the first switch Q1 and the fourth switch Q4. During this time, the timing control circuit 26 continues to input signals to the drive circuit 24 to turn off the second switch Q2 and the third switch Q3. That is, the timing control circuit 26 causes the drive circuit 24 to simultaneously turn off all the switches Q1, Q2, Q3, Q4. As a result, the timing control circuit 26 prevents through current from flowing between the reference level V0 and the high drive level VH through the on-state switches Q1, Q2, Q3, and Q4.

Thereafter, in the same manner as timing t1 to timing t5, the timing control circuit 26 inputs a signal for turning off each switch Q1, Q4 and a signal for turning on each switch Q2, Q3, and a signal for turning on each switch Q1. , Q4 and signals for turning off the switches Q2 and Q3 are alternately repeated. The drive circuit 24 repeats polarity inversion between the first output level SIGD1 and the second output level SIGD2.

On the other hand, from timing t1 to timing t4, the elapsed time T0 is equal to or less than the heating time TH, and the timer circuit 31 does not receive the switching signal SIGS. Therefore, the switching circuit 33 does not apply the drive voltage input from the drive circuit 24 to the light control sheet 10, and applies the heating voltage input from the heater power supply 32 to the light control sheet 10 to continue the heating state. The switching circuit 33 continues to heat the liquid crystal composition in the light control layer 13 by the heat generated by the first transparent electrode 11 and the heat generated by the second transparent electrode 12 .

Next, at timing t5, the elapsed time T0 exceeds the heating time TH, and the timer circuit 31 inputs the switching signal SIGS to the switching circuit 33 . The switching circuit 33 receives the switching signal SIGS and transitions from the heating state to the driving state. That is, the switching circuit 33 does not apply the heating voltage input from the heater power source 32 to the light control sheet 10 , but applies the drive voltage input from the drive circuit 24 to the light control sheet 10 . As a result, a voltage for changing the polarization direction of the liquid crystal molecules is applied to the heated liquid crystal molecules, and the heated liquid crystal molecules change the polarization direction.

As described above, according to the above embodiment, the following effects can be obtained.
(1-1) Application of voltage by the driving device 20 enables the liquid crystal composition to be heated, and the polarization direction of the liquid crystal molecules to be changed using the liquid crystal molecules in a heated state. As a result, even if the light control sheet 10 is placed under a low temperature such that the polarization direction of the liquid crystal molecules does not follow the change in the driving voltage, the polarization direction of the liquid crystal molecules can be changed. Therefore, the lower limit of the temperature at which the light control sheet 10 can be driven can be lowered.

(1-2) Since the switching circuit 33 switches between the application of the driving voltage and the application of the heating voltage, the heating of the liquid crystal molecules and the driving of the liquid crystal molecules can be performed separately. Therefore, it is possible to reduce the power consumption due to the application of the heating voltage during the period in which the heating of the light control sheet 10 is unnecessary.

(1-3) Application of a drive voltage at a low temperature in which the polarization direction of liquid crystal molecules does not follow changes in the drive voltage unnecessarily increases the power consumption of the light control device, and also increases the temperature of the liquid crystal composition. It delays raising. In this respect, the timer circuit 31 measures the elapsed time T0 after the power is turned on to the driving device 20, and when the elapsed time T0 exceeds the heating time TH, the switching circuit 33 is switched from the heating state to the driving state. A switching signal SIGS is input from the timer circuit 31 to the switching circuit 33 . Therefore, the application of the drive voltage is suppressed under low temperature such that the polarization direction of the liquid crystal molecules does not follow the change of the drive voltage.

(1-4) In order to cause the first transparent electrode 11 to generate heat using the first terminals 11P1 and 11P2 for applying the drive voltage, the first transparent electrode 11 is additionally provided with a terminal for applying the heating voltage. don't need it. In addition, since the second transparent electrode 12 is caused to generate heat using the second terminals 12P1 and 12P2 for applying the driving voltage, the second transparent electrode 12 does not need to be separately provided with a terminal for applying the heating voltage. Therefore, the configurations of the first transparent electrode 11 and the second transparent electrode 12 can be simplified.

In addition, the said 1st Embodiment can also be changed and implemented as follows.
The switching circuit 33 may be configured to switch from the heating state to the driving state based on an input other than the switching signal SIGS that the timer circuit 31 inputs.
The switching circuit 33 may store, for example, a learning result and an algorithm for deriving the heating time TH from the parameters indicating the usage status of the light control sheet 10 . Then, the switching circuit 33 may acquire a parameter indicating the actual usage status, and switch between the heating state and the driving state using the heating time TH derived using the parameter. Input examples other than the switching signal SIGS input to the timer circuit 31 are shown in a first modified example and a second modified example.

[First modified example]
- As FIG. 7 shows, the driving device 20 may further comprise a measuring circuit 41 .
The measurement circuit 41 measures the temperature of the light control sheet 10 and monitors whether the measured value exceeds the drivable temperature, which is a predetermined value. The measurement circuit 41 starts monitoring when the driving device 20 is powered on. The measurement circuit 41 inputs the drive permission signal SIGE to the switching circuit 33 when the measured value is the drivable temperature.

The drivable temperature is the temperature of the light control sheet 10 when the polarization direction of the liquid crystal molecules follows the driving voltage. The drivable temperature can vary depending on the compounding of each compound constituting the liquid crystal composition, the structure of the liquid crystal molecules, the driving voltage, etc., and is set based on the results of pre-implemented tests.

The measurement circuit 41 measures the type of the light control sheet 10, the temperature of the environment in which the light control sheet 10 is placed, the amount of change in the temperature, the amount of ultraviolet rays irradiated to the liquid crystal composition, the amount of change in the amount of ultraviolet rays, and Information may be stored that associates the period of continuous exposure to the environment with the drivable temperature. Then, based on various parameters input from the outside, the measurement circuit 41 may use the drivable temperature associated with the parameters to generate the drive permission signal SIGE.

Switching circuit 33 continues the standby state until drive device 20 is powered on. Switching circuit 33 determines whether measurement circuit 41 is inputting drive permission signal SIGE when drive device 20 is powered on. The switching circuit 33 transitions from the standby state to the driving state when the measurement circuit 41 determines that the drive permission signal SIGE is input.

On the other hand, when the switching circuit 33 determines that the measurement circuit 41 has not input the drive permission signal SIGE, the switch circuit 33 transitions from the standby state to the heating state. The switching circuit 33 continues the heating state from the time when the drive device 20 is powered on until the measurement circuit 41 inputs the drive permission signal SIGE. The switching circuit 33 transitions from the heating state to the driving state when the measurement circuit 41 receives the drive permission signal SIGE.

As described above, according to the first modified example, the following effects can be obtained.
(1-5) When the temperature of the light control sheet 10 is lower than the drivable temperature, the application of the drive voltage is prohibited and the application of the heating voltage is allowed. When the change cannot be followed, that is, when the liquid crystal composition requires heating, the heating becomes feasible.

(1-6) When the temperature of the light control sheet 10 is at the drivable temperature, the application of the heating voltage is prohibited and the application of the driving voltage is permitted. When the liquid crystal composition does not require heating, the heating can be prohibited.

In Modification 1, the measurement circuit 41 may monitor whether or not the temperature of the light control sheet 10 is at the drivable temperature after the switching circuit 33 has once transitioned to the drive state. At this time, the switching circuit 33 continues to be in the driving state during the period during which the measurement circuit 41 inputs the drive permission signal SIGE, and continues in the heating state during the period in which the measurement circuit 41 stops inputting the drive permission signal SIGE. good too.

The temperature of the light control sheet 10, once heated by the application of the heating voltage, drops during the period in which the heating voltage is not applied, that is, in the period in which the driving voltage is applied, and the polarization direction of the liquid crystal molecules changes again. It may not follow the drive voltage. In this respect, according to the modification, the heating of the liquid crystal molecules can be started when the polarization direction of the liquid crystal molecules does not follow the driving voltage again. Then, when the polarization direction of the liquid crystal molecules follows the driving voltage again, the heating of the liquid crystal molecules can be terminated.

In the above modified example, the driving device 20 includes the timer circuit 31 described in the first embodiment, and the liquid crystal molecules are heated for the heating time TH after the driving device 20 is powered on. is also possible.

[Second modification]
- As FIG. 8 shows, the drive device 20 may further be provided with the operation part 42. FIG.
The operation unit 42 receives an operation by the user and inputs a heating start signal SIGH and a heating end signal SIGL to the switching circuit 33 . The switching circuit 33 receives the heating start signal SIGH input from the operation unit 42, and transitions from the standby state or driving state to the heating state. The switching circuit 33 receives the heating end signal SIGL input from the operation unit 42, and transitions from the heating state to the driving state.

As described above, according to the second modification, the following effects can be obtained.
(1-7) The operating temperature at which the polarization direction of liquid crystal molecules can follow changes in driving voltage is likely to change depending on aging deterioration of the liquid crystal composition, frequency of use, and the like. In this regard, if the switching circuit 33 is configured to transition from the driving state to the heating state upon receiving the heating start signal SIGH from the operation unit 42, the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage. Heating of the liquid crystal molecules becomes feasible when a person recognizes it visually. As a result, the liquid crystal composition can be appropriately heated when the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage.

(1-8) When the user visually recognizes that the polarization direction of the liquid crystal molecules does not follow the change in the driving voltage, for example, when it is recognized that the entire surface of the light control sheet 10 does not follow the change. In some cases, it may be recognized that a part of the light control sheet 10 does not follow. In this respect, if the switching circuit 33 is configured to transition from the heating state upon receiving the heating end signal SIGL from the operation unit 42, the liquid crystal molecules are heated according to the extent to which it is recognized that the liquid crystal molecules are not following. The user can change the degree of

(Second embodiment)
2nd Embodiment of a light control apparatus is described with reference to FIGS. 9-11. It should be noted that the light control device of the second embodiment does not include the timer circuit 31, and uses a different driving voltage and heating voltage from those of the first embodiment, so that the driving voltage and the heating voltage can be applied simultaneously. It differs from the first embodiment.
Below, a different point from the light modulation apparatus of 1st Embodiment is mainly demonstrated, and the overlapping description is abbreviate|omitted about the structure similar to 1st Embodiment. The light control device of the second embodiment is an example in which the second transparent electrode included in the light control sheet is used as a heat source for the liquid crystal molecules, and the liquid crystal molecules are heated during the period in which the polarization direction of the liquid crystal molecules is changed. is.

As shown in FIG. 9, the booster circuit 23 generates a voltage for generating the drive voltage from the DC constant voltage input by the protection circuit 22 . A high drive level VH for generating a drive voltage is, for example, 50V. Also, the low drive level VL for generating the drive voltage is, for example, -50V. That is, the booster circuit 23 inputs the polarity-inverted drive levels VH and VL to the drive circuit 24 as voltage levels for generating drive voltages.

The drive circuit 24 comprises a fifth switch Q5 and a sixth switch Q6 directly connected to the fifth switch Q5. The fifth switch Q5 and the sixth switch Q6 constitute a CMOS transistor. A connecting portion between the fifth switch Q5 and the sixth switch Q6 is connected to the output end of the first output level SIGD1. The timing control circuit 26 controls the ON period of each switch Q5, Q6.

The timing control circuit 26 alternately repeats the high drive level VH and the low drive level VL with a dead time in between to suppress the through current from flowing between the high drive level VH and the low drive level VL. The potential difference between the high drive levels VH and VL is large enough to change the orientation of the liquid crystal molecules by applying a drive voltage under normal temperature and normal pressure. In addition, normal temperature is 20 degreeC and normal pressure is 1 atmosphere. The drive circuit 24 inputs the generated drive voltage only to the first terminal 11P1 of the first transparent electrode 11 . In addition, in the second embodiment, the second terminals 12P1 and 12P2 of the second transparent electrode 12 are kept connected to the ground level.

The timing control circuit 26 generates an inverted control signal SIGX, and inputs the generated inverted control signal SIGX to a switching circuit 33, which is an example of a switching section. The timing control circuit 26 measures, for example, the time during which the drive voltage is applied to the first transparent electrode 11, and generates an inversion control signal SIGX each time the inversion period TX of the application time elapses. The inversion period TX is, for example, 24 hours.

The switching circuit 33 is connected to the heater power supply 32 and the second terminals 12P1 and 12P2 of the second transparent electrode 12. As shown in FIG. The switching circuit 33 receives the inversion control signal SIGX input from the timing control circuit 26 and inverts the polarity of the heating voltage between the second terminals 12P1 and 12P2.

FIG. 10 is a timing chart showing the flow of heat processing and drive processing performed by the drive device 20. As shown in FIG. FIG. 10 shows changes in the states of the switches Q5 and Q6, the first output level SIGD1, the voltage level of the first terminal 11P1, and the voltage levels of the second terminals 12P1 and 12P2.

At timing t<b>0 , when the driving device 20 is powered on, the heater power supply 32 inputs the high level VMH and the low level VML to the switching circuit 33 . The switching circuit 33 inputs the low level VML to the second terminal 12P1 and inputs the high level VMH to the second terminal 12P2. As a result, the second transparent electrode 12 generates heat, and the liquid crystal composition in the light control layer 13 begins to be heated by the second transparent electrode 12 .

Next, from timing t1 to timing t2, the timing control circuit 26 inputs to the driving circuit 24 a signal for turning off the fifth switch Q5 and a signal for turning on the sixth switch Q6. As a result, the drive circuit 24 connects the low drive level VL input by the booster circuit 23 and the output end of the first output level SIGD1.

Next, from timing t2 to timing t3, the timing control circuit 26 inputs to the driving circuit 24 a signal for turning off the fifth switch Q5 and the sixth switch Q6. Thereby, the timing control circuit 26 sets a dead time to prevent a through current from flowing between the low drive level VL and the high drive level VH.

Next, from timing t3 to timing t4, the timing control circuit 26 inputs to the driving circuit 24 a signal for turning on the fifth switch Q5 and a signal for turning off the sixth switch Q6. As a result, the drive circuit 24 connects the high drive level VH input by the booster circuit 23 and the output end of the first output level SIGD1.

Next, from timing t4 to timing t5, the timing control circuit 26 inputs to the driving circuit 24 a signal for turning off the fifth switch Q5 and the sixth switch Q6. Thereby, the timing control circuit 26 sets a dead time to prevent a through current from flowing between the low drive level VL and the high drive level VH.

Thereafter, in the same manner as timing t1 to timing t5, the timing control circuit 26 repeats the input of signals for alternately turning on the switches Q5 and Q6, and the drive circuit 24 repeats the polarity inversion of the first output level SIGD1. .

Thus, the heating voltage is applied to the second transparent electrode 12 from timing t1 to timing t5, and the liquid crystal composition in the light control layer 13 is heated by the second transparent electrode 12. FIG. Further, a driving voltage that periodically inverts the polarity is applied to the liquid crystal composition, and the liquid crystal molecules are driven while being heated.

At this time, when the heating voltage is applied to the second transparent electrode 12 , a potential difference corresponding to the heating voltage is generated in the second transparent electrode 12 . If a driving voltage is applied between the transparent electrodes 11 and 12 while generating a potential difference in the plane of the second transparent electrode 12, the voltage applied to the liquid crystal composition can also be adjusted with variations corresponding to the heating voltage. It will continue to occur in the plane of the light sheet 10 . As a result, compared to the case where the voltage applied to the liquid crystal composition is uniform in the plane of the light control sheet 10, segregation of impurity ions and the like is more likely to occur.

In this regard, the timing control circuit 26 inputs the inverted control signal SIGX to the switching circuit 33 at timing t6. The switching circuit 33 inputs the high level VMH to the second terminal 12P1 and inputs the low level VML to the second terminal 12P2. Thereby, the switching circuit 33 inverts the polarity of the heating voltage between the second terminals 12P1 and 12P2.

Again, a heating voltage is applied to the second transparent electrode 12 to heat the liquid crystal composition in the light control layer 13 by the second transparent electrode 12 . Further, a driving voltage that periodically inverts the polarity is applied to the liquid crystal composition, and the liquid crystal molecules are driven while being heated. Even if variations in the applied voltage across the surface of the light control sheet 10 cause deviations in the physical properties of the liquid crystal composition, such deviations occur before and after the inversion control signal SIGX is input. After is entered, it will be canceled.

For example, as shown in FIG. 11, a low voltage dV1 is applied between the first terminal 11P1 and the second terminal 12P1 in the previous inversion period TX. On the other hand, it is assumed that a high voltage dV2 higher than the low voltage dV1 is applied between the first terminal 11P1 and the second terminal 12P2. The difference between the high voltage dV2 and the low voltage dV1 is of a magnitude corresponding to the heating voltage.

Then, in the current inversion period TX, a high voltage dV2 is applied between the first terminal 11P1 and the second terminal 12P1. On the other hand, a low voltage dV1 is applied between the first terminal 11P1 and the second terminal 12P2. As a result, even if variations in the applied voltage across the surface of the light control sheet 10 cause deviations in the physical property values of the liquid crystal composition, such deviations occur between the previous inversion period TX and the current inversion period TX. is canceled out by

As described above, according to the above embodiment, the following effects can be obtained.
(2-1) In the dimming process in which the application of the drive voltage and the application of the heating voltage are performed simultaneously, the polarity of the heating voltage is reversed between the second terminals 12P1 and 12P2 during the period in which the same process is performed. As a result, it is possible to prevent a potential difference, which may cause segregation of impurity ions, from continuing to occur throughout the duration of the dimming process.

(2-2) Since the polarity of the heating voltage that can cause segregation of impurity ions and the like is reversed at each inversion period TX, the effect of suppressing the segregation of impurity ions and the like can be obtained with high accuracy.

It should be noted that the above embodiment can also be implemented with the following modifications.
In the second embodiment, the timing control circuit 26 measures the period that has elapsed since the light control sheet 10 was placed on the object, and outputs an inversion control signal to the switching circuit 33 each time the period passes the inversion period TX. It may be configured to input SIGX.

- In the second embodiment, the timing control circuit 26 may store information that associates a parameter indicating the usage status of the light control sheet 10 with the inversion period TX. Then, the timing control circuit 26 may acquire a parameter indicating the actual usage status, and input the inversion control signal SIGX to the switching circuit 33 using the inversion period TX associated with the parameter. .

Alternatively, the timing control circuit 26 may store a learning result and an algorithm for deriving the inversion period TX from parameters indicating the usage status of the light control sheet 10 . Then, the timing control circuit 26 may acquire a parameter indicating the actual usage status, and input the inversion control signal SIGX to the switching circuit 33 using the inversion period TX derived using the parameter. .

As described above, variations in applied voltage across the surface of the light control sheet 10 cause unevenness in the distribution of physical properties of the liquid crystal composition through long-term use of the light control sheet 10 . At this time, the bias that can occur in the distribution of the physical property values of the liquid crystal composition is the type of the light control sheet 10, the temperature of the environment in which the liquid crystal composition is placed, the amount of change in the temperature, the amount of ultraviolet rays irradiated to the liquid crystal composition, It is affected by the amount of change in the amount of ultraviolet rays and the period of continuous exposure to the environment. In this respect, according to the above modification, the polarity of the heating voltage is reversed in a cycle that takes into consideration the usage of the light control sheet 10, so that the polarity of the heating voltage can be reversed in a more appropriate cycle. .

- In each embodiment, the object to which the heating voltage is applied may be only the second transparent electrode 12 . In this case, the first transparent electrode 11 may have only the first terminal 11P1 and the first terminal 11P2 may be omitted.

- In each embodiment, the part of the terminal to which the heating voltage is applied may be a terminal different from the terminal to which the driving voltage is applied. Furthermore, all of the terminals to which the heating voltage is applied may be terminals different from the terminals to which the driving voltage is applied.

- In each embodiment, the number of terminals to which the heating voltage is applied may be less than the number of terminals to which the drive voltage is applied. The voltage drop across the transparent electrodes 11 and 12 increases as the size of the light control sheet 10 increases. Therefore, in order to suppress variations in the drive voltage within the surface of the light control sheet 10, the light control device is provided with three or more terminals for each of the transparent electrodes 11 and 12, so that even if the drive voltage is applied from each terminal, good. According to this, the voltage drop in each transparent electrode 11 and 12 is suppressed.

- As shown in FIG. 12, in the second transparent electrode 12, the second terminals 12P1 and 12P2 may be arranged along a single common side. Furthermore, in the first transparent electrode 11 as well, the first terminals 11P1 and 11P2 may be arranged along a single common side. In short, the transparent electrode can function as a heat source for liquid crystal molecules as long as the transparent electrode has two or more terminals for applying a heating voltage to a single transparent electrode.

The transparent electrode for heating the liquid crystal molecules may include an electrode positioned on the low temperature side with respect to the liquid crystal molecules, between the first transparent electrode 11 and the second transparent electrode 12 . For example, when the light control sheet 10 is installed on a window that separates the room from the outside air in a cold climate, the transparent electrode for heating the liquid crystal molecules is positioned on the outside air side with respect to the liquid crystal molecules. may include According to this configuration, the heating time for causing the polarization direction of the liquid crystal molecules to follow the driving voltage can be shortened.

When the transparent electrodes for heating the liquid crystal molecules are both the first transparent electrode 11 and the second transparent electrode 12, even if the first transparent electrode 11 side with respect to the liquid crystal molecules has a relatively low temperature, Even if the second transparent electrode 12 side with respect to the liquid crystal molecules is at a relatively low temperature, the heating time can be shortened in any case.

At this time, the drive device 20 of the first embodiment receives an operation signal input from an external device such as the input unit 27 or the operation unit 42, and controls at least one of the first transparent electrode 11 and the second transparent electrode 12. The configuration may be such that a heating voltage is applied. In this modification, the electrode located on the low temperature side with respect to the liquid crystal molecules can function as a heat source in accordance with changes in the environment in which the light control device is placed.

Further, the driving device 20 of the second embodiment receives an operation signal input by an external device such as the input unit 27 or the operation unit 42, and selects one of the first transparent electrode 11 and the second transparent electrode 12. , may be applied with the drive voltage and the other may be applied with the heating voltage. Also in this modification, the electrode located on the low temperature side with respect to the liquid crystal molecules can function as a heat source in accordance with changes in the environment in which the light control device is placed.

Q1 to Q6 switches, SIGD1 first output level, SIGD2 second output level, SIGE drive enable signal, SIGH heating start signal, SIGL heating end signal, SIGS switching signal, SIGX reverse control signal, T0 Elapsed time TH Heating time V0 Reference level VH, VL Drive level VMH High level VML Low level 10 Light control sheet 11 First transparent electrode 11P1, 11P2 First Terminals 12 Second transparent electrode 12P1, 12P2 Second terminal 13 Light control layer 14, 15 Alignment film 20 Driving device 21 Power supply 22 Protection circuit 23 Booster circuit 24 Drive circuit 25 Voltage generating circuit 26 Timing control circuit 27 Input section 31 Timer circuit 32 Heater power supply 33 Switching circuit 41 Measurement circuit 42 Operation section.

Claims (6)

a light control sheet;
and a driving device for driving the light control sheet,
The light control sheet is
a first transparent electrode having a first terminal;
a second transparent electrode having a plurality of second terminals;
liquid crystal molecules held in a polymer network located between the first transparent electrode and the second transparent electrode;
The driving device
A heating voltage is applied between the second terminals, and a heating voltage is applied between the first terminal and the second terminal so that the polarization direction of the liquid crystal molecules is changed while the liquid crystal molecules are heated by the second transparent electrode. a drive unit that applies a drive voltage between
The drive unit
periodically inverting the polarity of the drive voltage during the period of applying the drive voltage;
reversing the polarity of the heating voltage during the period of applying the heating voltage;
The polarity of the heating voltage is changed so that the polarity of the heating voltage is reversed while the polarity is maintained during the application of the driving voltage and the heating voltage at the same time. invert
dimmer. The light control device according to claim 1 , wherein the driving section reverses the polarity of the heating voltage every predetermined period. 3. The driving unit according to claim 1 , wherein the driving unit switches between a state in which the application of the driving voltage and the application of the heating voltage is performed simultaneously and a state in which the application of the driving voltage and the application of the heating voltage are performed separately. dimmer. The drive unit applies the drive voltage and the heating voltage separately, and until a predetermined time elapses after power is turned on to the drive device, prior to the application of the drive voltage, the drive unit The light control device according to claim 3 , wherein the heating voltage is applied between second terminals. a temperature of the light control sheet when the polarization direction of the liquid crystal molecules follows the driving voltage is a predetermined drivable temperature;
The drive unit
A measuring unit for measuring the temperature of the light control sheet,
As a state in which the application of the driving voltage and the application of the heating voltage are performed separately,
When the measured value of the measuring unit is lower than the drivable temperature, the application of the heating voltage is permitted and the application of the driving voltage is prohibited, and when the measured value of the measuring unit is the drivable temperature. 5. The light control device according to claim 3 or 4, wherein application of the heating voltage is prohibited and application of the driving voltage is allowed. A light control sheet driving method for driving a light control sheet,
The light control sheet is
a first transparent electrode having a first terminal;
a second transparent electrode having a plurality of second terminals;
liquid crystal molecules held in a polymer network located between the first transparent electrode and the second transparent electrode;
A heating voltage is applied between the second terminals, and a heating voltage is applied between the first terminal and the second terminal so that the polarization direction of the liquid crystal molecules is changed while the liquid crystal molecules are heated by the second transparent electrode. simultaneously applying a driving voltage between and reversing the polarity of the heating voltage during the period of simultaneous application;
periodically inverting the polarity of the drive voltage during the period of applying the drive voltage;
reversing the polarity of the heating voltage during the period of applying the heating voltage;
The polarity of the heating voltage is changed so that the polarity of the heating voltage is reversed while the polarity is maintained during the application of the driving voltage and the heating voltage at the same time. invert
Driving method of the light control sheet.