JP2020194086A - Light control device and method for driving light control sheet - Google Patents

Abstract

To provide a light control device which can drop the lower limit of temperatures which can make a light control sheet drive, and a method for driving the light control sheet.SOLUTION: A voltage for changing the direction of polarization of liquid crystal molecules contained in a liquid crystal composition is a driving voltage, and a voltage for causing a second transparent electrode 12 to generate heat is a heating voltage. A driving device has a driving unit for performing application of the heating voltage across second terminals 12P1 and 12P2 to change the direction of polarization of liquid crystal molecules while the liquid crystal composition is heated by the second transparent electrode 12 and performing application of the driving voltage across first terminals 11P1, 11P2 and the second terminals 12P1 and 12P2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dimming device provided with a dimming sheet and a method for driving the dimming sheet.

The light control sheet comprises 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 changes in voltage between the transparent electrodes. The drive device of the light control sheet applies an AC voltage between the 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).

The types of dimming sheets are classified into normal type and reverse type. In the normal type, the dimming layer when not energized is opaque, and the dimming layer when energized is transparent. The normal type is suitable for application to screens and the like that frequently require light shielding. In the reverse type, the dimming layer when not energized is transparent, and the dimming layer when energized is opaque (see, for example, Patent Document 2). The reverse type is suitable for application to building materials and the like that require safety due to transparency in an emergency.

Japanese Unexamined Patent Publication No. 2018-091986 Japanese Unexamined Patent Publication No. 2000-321562

In recent years, the range of application of dimming sheets has been steadily expanding, and along with this, the use of dimming sheets in low temperatures such as cold regions is being considered. Then, when the dimming sheet is used at a low temperature, there is a new problem that the orientation of the liquid crystal molecules does not easily follow the change in voltage.
An object of the present invention is to provide a dimming device capable of lowering the lower limit of the temperature at which a dimming sheet can be driven, and a method for driving the dimming sheet.

The dimming device for solving the above problems includes a dimming sheet and a driving device for driving the dimming sheet. The dimming sheet is a liquid crystal located between a first transparent electrode having a first terminal, a second transparent electrode having a plurality of second terminals, and the first transparent electrode and the second transparent electrode. With a molecule. The drive device applies a heating voltage between the second terminals so as to change the polarization direction of the liquid crystal molecules while the liquid crystal molecules are heated by the second transparent electrode, and the first terminal and the drive device. A drive unit for applying a drive voltage to and from the second terminal is provided.

The method for driving the dimming sheet for solving the above problems is a method for driving the dimming sheet for driving the dimming sheet, wherein the dimming sheet includes a first transparent electrode provided with a first terminal and a plurality of the dimming sheets. The second transparent electrode provided with the second transparent electrode and the liquid crystal molecule located between the first transparent electrode and the second transparent electrode are provided, and the liquid crystal molecule is heated to the second transparent electrode. The heating voltage is applied between the second terminals and the driving voltage is applied between the first terminal and the second terminal at the same time so as to change the polarity direction of the liquid crystal molecules in the state. The polarity of the heating voltage is reversed during the period of simultaneous application.

According to each of the above configurations, the application of a voltage by the driving device makes the liquid crystal molecules heatable, and the liquid crystal molecules in the heated state can be used to change the polarization direction of the liquid crystal molecules. As a result, even if the dimming sheet is placed at a low temperature at which the polarization direction of the liquid crystal molecules does not follow the change in voltage, the application of the voltage by the driving device makes it possible to change the polarization direction of the liquid crystal molecules. Therefore, the lower limit of the temperature at which the dimming sheet can be driven is lowered.
In the dimming device, the driving unit may invert the polarity of the heating voltage during a period in which the driving voltage is applied and the heating voltage is applied at the same time.

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

In this regard, 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 driving voltage and the application of the heating voltage are executed at the same time. As a result, it is possible to prevent a potential difference that causes segregation of impurity ions and the like from occurring over the entire period during which the drive voltage is applied and the heating voltage is applied at the same time. As a result, 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 dimming device, the driving unit may invert the polarity of the heating voltage at predetermined intervals. According to this configuration, the polarity of the potential difference that causes segregation of impurity ions and the like is reversed at predetermined periods, so that the effect of suppressing segregation of impurity ions and the like can be obtained with high accuracy.

In the dimming device, the drive unit may switch between the application of the heating voltage and the application of the drive voltage. According to this configuration, since the application of the heating voltage and the application of the drive voltage are executed separately, the power consumption due to the application of the heating voltage can be suppressed during the period when the heating of the dimming sheet is unnecessary.

In the dimming device, the drive unit applies the heating voltage between the second terminals prior to the application of the drive voltage until a predetermined time elapses after the power is turned on to the drive device. You may.

The application of the driving voltage at a low temperature where the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage unnecessarily increases the power consumption in the dimming device and delays the increase in the temperature of the liquid crystal molecules. .. In this regard, 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, 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 is suppressed.

In the dimming device, the temperature of the dimming sheet when the polarization direction of the liquid crystal molecule follows the driving voltage is a predetermined driveable temperature, and the driving unit measures the temperature of the dimming sheet. A measuring unit is provided, and when the measured value of the measuring unit is lower than the driveable temperature, the application of the heating voltage is allowed and the application of the driving voltage is prohibited, and the measured value of the measuring unit can be driven. When the temperature is high, the application of the heating voltage may be prohibited and the application of the drive voltage may be allowed.

According to the above configuration, when the temperature of the light control sheet is lower than the driveable temperature, the application of the drive voltage is prohibited and the application of the heating voltage is allowed, so that the polarization direction of the liquid crystal molecules is the drive voltage. The heating is performed when the change cannot be followed, that is, when the liquid crystal molecules require heating. Further, when the temperature of the light control sheet is the driveable 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 of the drive voltage. Occasionally, that is, when the liquid crystal molecules do not require heating, their heating can be prohibited.

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

The block diagram which shows the structure of the light control sheet provided in 1st Embodiment of a light control device. The cross-sectional view which shows the cross-sectional structure of the normal type dimming sheet. The cross-sectional view which shows the cross-sectional structure of the reverse type dimming sheet. The block diagram which shows the electrical structure in 1st Embodiment of a dimmer. A circuit diagram showing a configuration of a drive circuit included in a dimmer. A timing chart showing an example of the flow of heat treatment performed by a dimmer. The block diagram which shows the electric structure in the dimmer of the 1st modification example. The block diagram which shows the electric structure in the dimmer of the 2nd modification example. The block diagram which shows a part of the electric structure included in the 2nd Embodiment of a dimmer. A timing chart showing an example of the flow of heat treatment performed by a dimmer. The graph which shows the transition of the voltage level in the heat treatment performed by a dimmer. The block diagram which shows the structure of the light control sheet provided in the light control device of the modified example.

(First Embodiment)
A first embodiment of the dimming device will be described with reference to FIGS. 1 to 6. Hereinafter, the layer structure of the light control sheet, the electrical structure of the light control device, the heat treatment performed by the light control device, and the drive process performed by the light control device will be described in this order.

The dimming device of the first embodiment is an example in which both the first transparent electrode and the second transparent electrode included in the dimming sheet are used as heating 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 during the period.

[Dimming sheet 10]
FIG. 1 is an exploded perspective view showing the dimming sheet 10 decomposed into three functional layers. Each functional layer may have a single layer structure or may have a laminated multi-layer structure.

The dimming sheet 10 is attached to, for example, a window provided in a moving body such as a vehicle or an aircraft. Even if the dimming sheet 10 is attached to a window provided in various buildings such as a house, a station, an airport, a partition installed in an office, a show window installed in a store, a moving body such as an automatic door, or the like. Good.

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

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

The reverse type dimming sheet 10 has a high light transmittance when the dimming sheet 10 is energized and a low light transmittance when the dimming sheet 10 is not energized. The reverse type dimming sheet 10 is opaque when the dimming sheet 10 is energized and transparent when the dimming sheet 10 is not energized.
The transparency 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 dimming sheet 10. Opacity is a state in which the presence or absence of an object cannot be visually recognized through the dimming sheet 10. The transparency may be a state in which the shape and type of an object can be visually recognized through the dimming sheet 10. The opacity may be a state in which the shape and type of the object cannot be visually recognized through the dimming sheet 10.

The light control sheet 10 includes a first transparent electrode 11 and a second transparent electrode 12. Each transparent electrode 11, 12 is supported by a separate transparent body. The 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 dimming sheet 10 includes a dimming layer 13. The dimming layer 13 is located 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 of the transparent electrodes 11 and 12 has visible light transmission. Visible light transmission enables visual recognition of an object through the dimming sheet 10. The material constituting each of the transparent electrodes 11 and 12 is 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). It is one of them.

The dimming layer 13 contains a liquid crystal composition. The dimming layer 13 is regarded as a parallel circuit of a capacitance component and a resistance component. Examples of liquid crystal molecules contained in the liquid crystal composition include Schiff base type, azo type, azoxy type, biphenyl type, terphenyl type, benzoic acid ester type, trans type, pyrimidine type, cyclohexanecarboxylic acid ester type, phenylcyclohexane type, It is a type selected from the group consisting of dioxane systems.

The holding type of the liquid crystal composition is any one selected from the group consisting of a polymer network type, a polymer dispersion type, and a capsule type. The polymer network type includes a polymer network having a three-dimensional network, and holds the liquid crystal composition in the network-like voids communicating with each other. 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. In the capsule type, the liquid crystal composition having a capsule shape is held in the polymer layer.

The first transparent electrode 11 includes 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, for example, one of the first terminals 11P1 extends along the upper side of the first transparent electrode 11. Further, the other first terminal 11P2 extends along the lower side of the first transparent electrode 11.

The second transparent electrode 12 includes 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, 12P2 are arranged at positions that do not overlap with the pair of first terminals 11P1, 11P2 in the stacking direction. When the second transparent electrode 12 has a rectangular shape, for example, one of the second terminals 12P1 extends along the right side of the second transparent electrode 12. Further, the other second terminal 12P2 extends along the left side of the second transparent electrode 12.

FIG. 2 shows an example of the layer structure included in the normal type dimming sheet 10.
As shown in FIG. 2, the normal type dimming sheet 10 includes a first transparent electrode 11, a second transparent electrode 12, and a dimming 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 unit.

When the switching circuit 33 applies a drive voltage to the normal type dimming sheet 10, the first terminals 11P1 and 11P2 of the first transparent electrode 11 have a first output level which is a voltage level at the output end of the switching circuit 33. SIGD1 is input. Further, the second output level SIGD2, which is the voltage level at the other output terminals of the switching circuit 33, is input to the second terminals 12P1 and 12P2 of the second transparent electrode 12.

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

When the first output level SIGD1 and the second output level SIGD2 have the same voltage level as each other, for example, when the two transparent electrodes 11 and 12 are connected to the ground level, the normal type dimming sheet 10 is a liquid crystal display. The direction of polarization of the molecule is disordered. When the polarization direction of the liquid crystal molecules is disordered, the light transmittance of the normal type dimming sheet 10 is relatively low.

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

FIG. 3 shows an example of the layer structure included in the reverse type dimming 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 located 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 dimming layer 13 and the second transparent electrode 12, and is in contact with the dimming layer 13.

The material constituting the first alignment film 14 and the second alignment film 15 is, for example, an organic compound such as polyimide, polyamide, polyvinyl alcohol, or cyanide compound, an inorganic compound such as silicone, silicon oxide, or zirconium oxide, or , Consists of a mixture of these.

The alignment film 14 and the second alignment film 15 are, for example, a vertical alignment film or a horizontal alignment film. The vertical alignment film orients the polarization direction of the liquid crystal molecules so as to be 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 orients the polarization direction of the liquid crystal molecules so as to be substantially parallel to the electrode surface of the first transparent electrode 11 and the electrode surface of the second transparent electrode 12.

When the switching circuit 33 applies a drive voltage to the reverse type dimming sheet 10, the first output level SIGD1 is connected to the first terminals 11P1 and 11P2 of the first transparent electrode 11 as in the normal type dimming sheet 10. Upon input, the 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 have the same voltage level, for example, when the two transparent electrodes 11 and 12 are connected to the ground level, the reverse type dimming sheet 10 is adjusted. The polarization directions of the liquid crystal molecules are aligned by the alignment films 14 and 15 so that the light layer 13 transmits visible light. When the polarization directions of the liquid crystal molecules are aligned, the light transmittance of the reverse type dimming sheet 10 is relatively high.

When the potential difference between the first output level SIGD1 and the second output level SIGD2 is equal to or greater than a predetermined value, that is, when the voltage between the two transparent electrodes 11 and 12 is equal to or greater than a predetermined value, the reverse type dimming sheet 10 is used. , The polarization directions of the liquid crystal molecules are aligned so that the dimming 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 dimming sheet 10 is relatively low.

[Dimming sheet drive device]
FIG. 4 is a block diagram functionally showing the configuration of the drive device 20.
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 26.
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 fuse to cut off the connection between the power supply 21 and the booster circuit 23 and the connection between the power supply 21 and the voltage generation circuit 25. The fuse included in the protection circuit 22 has a large blown current so as not to be blown by a ripple of a normal current.

The booster circuit 23 generates a voltage for generating a drive voltage from the DC constant voltage input by the protection circuit 22. The high drive level VH for generating the drive voltage is, for example, 50V. The drive voltage has a waveform in which a high drive level VH and a reference level V0 are alternately repeated. The high drive level VH is large enough to change the orientation of the liquid crystal molecules by applying a drive voltage under normal temperature and pressure. The normal temperature is 20 ° C., and the normal pressure is 1 atm.

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

More specifically, when the drive circuit 24 outputs the drive voltage, the first output level SIGD1 alternately switches 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. Further, when the drive circuit 24 outputs the drive voltage, the second output level SIGD2 also switches between the high drive level VH and the reference level V0 alternately.

The voltage generation circuit 25 is connected to 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. 5, the drive circuit 24 includes a full bridge circuit composed 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. Further, the third switch Q3 is a p-channel type transistor. The fourth switch Q4 is an n-channel transistor. The third switch Q3 and the fourth switch Q4 form 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 first switch Q1 and the second switch Q2 connected in series, and the third switch Q3 and the fourth switch Q4 connected in series are connected in parallel. The connection portion between the first switch Q1 and the second switch Q2 is connected to the output end of the first output level SIGD1. The connection 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 included in the full bridge circuit.

The timing control circuit 26 includes an arithmetic processing unit and a memory. The timing control circuit 26 is not limited to processing all kinds of processing by software. For example, the timing control circuit 26 may include dedicated hardware (integrated circuit for a specific application: ASIC) that executes at least a part of various processes. The timing control circuit 26 is configured as a circuit including one or more dedicated hardware circuits such as an ASIC, one or more processors (microcomputers) operating according to a computer program (software), or a combination thereof. May be good.

In the following, an example will be described in which the timing control circuit 26 stores a drive program in a readable 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 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 the switches Q2 and Q3.

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

The timing control circuit 26 may, for example, control the on period of each switch Q1, Q2, Q3, Q4 to change the pulse width of the drive voltage which is the repetition of the voltage pulse. The change of the pulse width changes the effective value of the voltage applied to the dimming layer 13 to increase the visible light transmittance of the dimming layer 13 to multiple gradations. The timing control circuit 26 may determine the gradation value of the visible light transmittance included in the dimming sheet 10 based on the operation signal input from the input unit 27. The operation signal input from the input unit 27 is generated by pressing an operation button for increasing or decreasing the visible light transmittance step by step, or an operation of making the dimming sheet 10 transparent or opaque. Generated by pressing a button.

[Heating voltage]
Returning to FIG. 4, the drive 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 unit.

The timer circuit 31 is connected to the power supply 21 and the switching circuit 33. The timer circuit 31 receives the DC constant voltage input by the power supply 21 and measures the elapsed time since the power is turned on to the drive device 20. The power is turned on to the drive device 20, for example, when an operation signal for activating the dimming 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 a 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 a time for heating the liquid crystal molecules contained in the liquid crystal composition, and is a time for making the polarization direction of the liquid crystal molecules follow the driving voltage. The heating time TH raises the temperature of the dimming sheet 10 from, for example, the lower limit of the temperature at which the dimming device can be used to the lower limit of the 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 tests and the like conducted in advance.

The heater power supply 32 is connected to the power supply 21 and the switching circuit 33. The heater power supply 32 receives a DC constant voltage input by the power supply 21 and generates a heating voltage for heating the first transparent electrode 11 and the second transparent electrode 12. The heating voltage is a DC constant voltage, which 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. The high level VMH is, for example, 10V and the low level VML is, for example, -10V.

The switching circuit 33 is connected to the first terminals 11P1, 11P2 of the first transparent electrode 11 and the second terminals 12P1, 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, 11P2 and the second terminals 12P1, 12P2.
The heating state switching circuit 33 inputs a high level VMH to the first terminal 11P1 and the second terminal 12P1, and inputs a 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 the transparent electrodes 11 and 12.

The drive 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 drive state switching circuit 33 applies a drive voltage between the transparent electrodes 11 and 12.

The switching circuit 33 continues the standby state until the power is turned on to the drive device 20. The switching circuit 33 transitions from the standby state to the heating state when the power is turned on to the drive device 20. The switching circuit 33 continues the heating state from the time when the power is turned on to the drive device 20 until the timer circuit 31 inputs the switching signal SIGS. The switching circuit 33 transitions from the heated 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 drive device 20. FIG. 6 shows the states of switches Q1, Q2, Q3, and Q4, the first output level SIGD1, the second output level SIGD2, the voltage levels of the first terminals 11P1, 11P2, and the transition of the voltage levels of the second terminals 12P1, 12P2. Is shown.

As shown in FIG. 6, when the power is turned on to the drive device 20 at the timing t0, the timer circuit 31 starts measuring the elapsed time T0. The heater power supply 32 inputs the high level VMH and the low level VML to the 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. Further, the switching circuit 33 inputs a high level VMH to the second terminal 12P1 and inputs a low level VML to the second terminal 12P2. As a result, the second transparent electrode 12 begins to generate heat, and the liquid crystal composition of 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 receives 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. , Is 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 a signal for turning off the second switch Q2 and the third switch Q3 to the drive circuit 24. During this time, the timing control circuit 26 continues to input a signal for turning off the first switch Q1 and the fourth switch Q4 to the drive circuit 24. That is, the timing control circuit 26 causes the drive circuit 24 to turn off all the switches Q1, Q2, Q3, and Q4 at the same time. As a result, the timing control circuit 26 prevents a through current from flowing between the reference level V0 and the high drive level VH through the switches Q1, Q2, Q3, and Q4 in the on state.

Next, from timing t3 to timing t4, the timing control circuit 26 receives 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. , Is 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 a signal for turning off the first switch Q1 and the fourth switch Q4 to the drive circuit 24. During this time, the timing control circuit 26 continues to input a signal for turning off the second switch Q2 and the third switch Q3 to the drive circuit 24. That is, the timing control circuit 26 causes the drive circuit 24 to turn off all the switches Q1, Q2, Q3, and Q4 at the same time. As a result, the timing control circuit 26 prevents a through current from flowing between the reference level V0 and the high drive level VH through the switches Q1, Q2, Q3, and Q4 in the on state.

After that, similarly to the timing t1 to the timing t5, the timing control circuit 26 inputs a signal for turning off the switches Q1 and Q4, a signal for turning on the switches Q2 and Q3, and each switch Q1. , The signal for turning on Q4 and the input of the signal for turning off each of the switches Q2 and Q3 are alternately repeated. The drive circuit 24 repeats the reversal of polarity between the first output level SIGD1 and the second output level SIGD2.

On the other hand, from the timing t1 to the timing t4, the elapsed time T0 is equal to or less than the heating time TH, and the timer circuit 31 does not input the switching signal SIGS. Therefore, the switching circuit 33 does not apply the drive voltage input by the drive circuit 24 to the dimming sheet 10, but applies the heating voltage input by the heater power supply 32 to the dimming sheet 10 to continue the heating state. Then, 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 the 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 input of the switching signal SIGS and transitions from the heated state to the driving state. That is, the switching circuit 33 does not apply the heating voltage input by the heater power supply 32 to the dimming sheet 10, but applies the driving voltage input by the drive circuit 24 to the dimming 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 effects listed below can be obtained.
(1-1) The application of a voltage by the driving device 20 makes the liquid crystal composition heatable, and the liquid crystal molecules in the heated state can be used to change the polarization direction of the liquid crystal molecules. As a result, even if the dimming sheet 10 is placed at a low temperature such that the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage, the polarization direction of the liquid crystal molecules can be changed. Therefore, the lower limit of the temperature at which the dimming 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 executed separately. Therefore, during the period when the dimming sheet 10 does not need to be heated, the power consumption due to the application of the heating voltage can be reduced.

(1-3) The application of the driving voltage at a low temperature where the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage unnecessarily increases the power consumption in the dimmer, and also raises the temperature of the liquid crystal composition. It delays raising. In this regard, the timer circuit 31 measures the elapsed time T0 since the power is turned on to the drive device 20, and when the elapsed time T0 exceeds the heating time TH, the switching circuit 33 is switched from the heated state to the driven state. The switching signal SIGS is input from the timer circuit 31 to the switching circuit 33. Therefore, the application of the driving voltage is suppressed at a low temperature where the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage.

(1-4) In order to heat the first transparent electrode 11 by using the first terminals 11P1 and 11P2 for applying the driving voltage, the first transparent electrode 11 is provided with a terminal for applying the heating voltage separately. I don't need it. Further, since the second transparent electrode 12 is heated by using the second terminals 12P1 and 12P2 for applying the driving voltage, it is not necessary to separately provide the second transparent electrode 12 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.

The first embodiment may be modified as follows.
The switching circuit 33 may be configured to switch from the heated state to the driving state based on an input other than the switching signal SIGS input by the timer circuit 31.
The switching circuit 33 may store, for example, a learning result and an algorithm for deriving the heating time TH from a parameter indicating the usage status of the dimming sheet 10. Then, the switching circuit 33 may be configured to acquire a parameter indicating an actual usage state and switch between a heating state and a driving state by using the heating time TH derived by using the parameter. An input example other than the switching signal SIGS input by the timer circuit 31 is shown in the first modification example and the second modification example.

[First modification example]
-As shown in FIG. 7, the drive device 20 may further include a measurement circuit 41.
The measuring circuit 41 measures the temperature of the dimming sheet 10 and monitors whether or not the measured value exceeds the driveable temperature which is a predetermined value. The measurement circuit 41 starts monitoring when the power is turned on to the drive device 20. The measurement circuit 41 inputs the drive permission signal SIGE to the switching circuit 33 when the measured value is the driveable temperature.

The driveable temperature is the temperature of the dimming sheet 10 when the polarization direction of the liquid crystal molecules follows the drive voltage. The driveable temperature can change depending on the composition of each compound constituting the liquid crystal composition, the structure of the liquid crystal molecules, the drive voltage, and the like, and is set based on the results of tests and the like conducted in advance.

The measurement circuit 41 describes 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 that associates the period of being placed in the environment with the driveable temperature may be stored. Then, the measurement circuit 41 may use the driveable temperature associated with the parameters based on various parameters input from the outside to generate the drive permission signal SIGE.

The switching circuit 33 continues the standby state until the power is turned on to the drive device 20. The switching circuit 33 determines whether or not the measuring circuit 41 is inputting the drive permission signal SIGE when the power is turned on to the drive device 20. When the switching circuit 33 determines that the measurement circuit 41 is inputting the drive permission signal SIGE, the switching circuit 33 transitions from the standby state to the drive state.

On the other hand, when the measurement circuit 41 determines that the drive permission signal SIGE has not been input, the switching circuit 33 transitions from the standby state to the heating state. The switching circuit 33 continues to be in a heated state from the time when the power is turned on to the drive device 20 until the measurement circuit 41 inputs the drive permission signal SIGE. Then, when the measurement circuit 41 inputs the drive permission signal SIGE, the switching circuit 33 transitions from the heated state to the drive state.

As described above, according to the first modification, the effects listed below can be obtained.
(1-5) When the temperature of the dimming sheet 10 is lower than the driveable temperature, the application of the drive voltage is prohibited and the application of the heating voltage is allowed, so that the polarization direction of the liquid crystal molecules is the drive voltage. When the change cannot be followed, that is, when the liquid crystal composition requires heating, the heating becomes feasible.

(1-6) Further, when the temperature of the dimming sheet 10 is the driveable 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 is the drive voltage. When the liquid crystal composition can follow the change of, that is, when the liquid crystal composition does not require heating, the heating can be prohibited.

-In the above modification 1, the measurement circuit 41 may monitor whether or not the temperature of the dimming sheet 10 is the driveable temperature after the switching circuit 33 has once transitioned to the drive state. At this time, the switching circuit 33 continues the driving state for the period when the measuring circuit 41 inputs the drive permission signal SIGE, and continues the heating state for the period when the measuring circuit 41 stops the input of the driving permission signal SIGE. May be good.

The dimming sheet 10 once raised by the application of the heating voltage is cooled during the period when the heating voltage is not applied, that is, during the period when the driving voltage is applied, and the polarization direction of the liquid crystal molecules is changed again. It may not follow the drive voltage. In this regard, according to the above modified example, 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 modification, the drive device 20 includes the timer circuit 31 described in the first embodiment, and heats the liquid crystal molecules for the heating time TH after the power is turned on to the drive device 20. It is also possible.

[Second modification example]
As shown in FIG. 8, the drive device 20 may further include an operation unit 42.
The operation unit 42 receives an operation by the user and inputs the heating start signal SIGH and the heating end signal SIGL to the switching circuit 33. The switching circuit 33 receives the heating start signal SIGH input by the operation unit 42, and transitions from the standby state or the driving state to the heating state. The switching circuit 33 receives the heating end signal SIGL input by the operation unit 42, and transitions from the heating state to the driving state.

As described above, according to the second modification, the effects listed below can be obtained.
(1-7) The operating temperature at which the polarization direction of the liquid crystal molecules can follow the change in the driving voltage is likely to change depending on the aging deterioration of the liquid crystal composition and the frequency of use. In this regard, if the switching circuit 33 is configured to transition from the driving state to the heating state in response to the heating start signal SIGH from the operation unit 42, it is utilized that the polarization direction of the liquid crystal molecules does not follow the change of the driving voltage. When a person visually recognizes, heating of liquid crystal molecules becomes feasible. 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 in 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 dimming sheet 10 does not follow. In some cases, it may be recognized that a part of the dimming sheet 10 does not follow. In this regard, if the switching circuit 33 is configured to transition from the heated state in response to the heating end signal SIGL from the operation unit 42, the liquid crystal molecules are heated according to the degree to which it is recognized that the liquid crystal molecules are not following. The user can change the degree of.

(Second Embodiment)
A second embodiment of the dimming device will be described with reference to FIGS. 9 to 11. The dimming device of the second embodiment does not include the timer circuit 31, and the drive voltage and the heating voltage can be applied at the same time by using a drive voltage and a heating voltage different from those of the first embodiment. It is different from the first embodiment.
In the following, the points different from the dimming device of the first embodiment will be mainly described, and the duplicated description of the same configuration as that of the first embodiment will be omitted. The dimming device of the second embodiment is an example in which the second transparent electrode included in the dimming sheet is used as a heating source for the liquid crystal molecules, and is an example in which the liquid crystal molecules are heated during the period of changing the polarization direction of the liquid crystal molecules. Is.

As shown in FIG. 9, the booster circuit 23 generates a voltage for generating a drive voltage from the DC constant voltage input by the protection circuit 22. The high drive level VH for generating the drive voltage is, for example, 50V. Further, the low drive level VL for generating the drive voltage is, for example, −50 V. 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 the drive voltage.

The drive circuit 24 includes 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 form a CMOS transistor. The connection 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 and 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 in order to prevent a 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 such that the orientation of the liquid crystal molecules can be changed by applying a drive voltage under normal temperature and pressure. The normal temperature is 20 ° C., and the normal pressure is 1 atm. The drive circuit 24 inputs the generated drive voltage only to the first terminal 11P1 of the first transparent electrode 11. In the second embodiment, the second terminals 12P1 and 12P2 of the second transparent electrode 12 continue to be connected to the ground level.

The timing control circuit 26 generates an inverting control signal SIGX, and inputs the generated inverting control signal SIGX to the switching circuit 33, which is an example of the switching unit. The timing control circuit 26 measures, for example, the time when the drive voltage is applied to the first transparent electrode 11, and generates an inversion control signal SIGX every time the application time elapses in the inversion cycle TX. 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. The switching circuit 33 receives the inverting control signal SIGX input by 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 heat treatment performed by the drive device 20 and the flow of the drive process. FIG. 10 shows the states of the switches Q5 and Q6, the voltage level of the first output level SIGD1, the first terminal 11P1, and the transition of the voltage level of the second terminals 12P1 and 12P2.

When the power is turned on to the drive device 20 at the timing t0, 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 a low level VML to the second terminal 12P1 and inputs a 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 a signal for turning off the fifth switch Q5 and a signal for turning on the sixth switch Q6 to the drive circuit 24. 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 a signal for turning off the fifth switch Q5 and the sixth switch Q6 to the drive circuit 24. As a result, the timing control circuit 26 sets a dead time and prevents 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 a signal for turning on the fifth switch Q5 and a signal for turning off the sixth switch Q6 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.

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

After that, similarly to the timing t1 to the 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 reversal of the first output level SIGD1. ..

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

At this time, when a 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 causing a potential difference in the plane of the second transparent electrode 12, the voltage applied to the liquid crystal composition also adjusts the variation corresponding to the heating voltage. It will continue to occur in the plane of the optical sheet 10. As a result, segregation of impurity ions and the like is more likely to occur as compared with the case where the voltage applied to the liquid crystal composition is uniform in the plane of the light control sheet 10.

In this regard, the timing control circuit 26 inputs the inversion control signal SIGX to the switching circuit 33 at the timing t6. Then, 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 switching circuit 33 inverts the polarity of the heating voltage between the second terminals 12P1 and 12P2.

Here, too, a heating voltage is applied to the second transparent electrode 12, and the liquid crystal composition in the light control layer 13 is heated by the second transparent electrode 12. Further, a driving voltage that periodically reverses the polarity is applied to the liquid crystal composition, and the liquid crystal molecules are driven while being heated. Even if the variation in the applied voltage in the surface of the light control sheet 10 causes a bias in the physical property values of the liquid crystal composition, such a bias occurs before the inversion control signal SIGX is input and in the inversion control signal SIGX. Will be offset after is entered.

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 cycle 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 a magnitude corresponding to the heating voltage.

Then, in the inversion cycle TX this time, 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 the variation in the applied voltage in the surface of the light control sheet 10 causes a bias in the physical property values of the liquid crystal composition, such a bias is between the previous inversion period TX and the current inversion period TX. Is offset by.

As described above, according to the above embodiment, the effects listed below can be obtained.
(2-1) In the dimming process in which the drive voltage is applied and the heating voltage is applied at the same time, the polarity of the heating voltage is reversed between the second terminals 12P1 and 12P2 during the period during which the process is performed. As a result, it is possible to prevent a potential difference that can cause segregation of impurity ions and the like from continuing to occur during the entire dimming treatment.

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

The above embodiment can also be modified as follows.
-In the second embodiment, the timing control circuit 26 measures the period elapsed since the dimming sheet 10 is installed on the target, and each time the period elapses in the inversion cycle TX, the inversion control signal is sent to the switching circuit 33. It may be configured to input SIGX.

-In the second embodiment, the timing control circuit 26 may store information in which a parameter indicating the usage status of the dimming sheet 10 and the inversion period TX are associated with each other. Then, the timing control circuit 26 may be configured to acquire a parameter indicating an actual usage status and input the inversion control signal SIGX to the switching circuit 33 by using the inversion cycle TX associated with the parameter. ..

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

As described above, the variation in the applied voltage in the surface of the dimming sheet 10 causes a bias in the distribution of the physical property values of the liquid crystal composition over a long period of use of the dimming sheet 10. At this time, the bias that can occur in the distribution of the physical property values of the liquid crystal composition includes the model 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, and so on. 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 regard, according to the above modification example, since the polarity reversal of the heating voltage is executed at a cycle in which the usage status of the light control sheet 10 is taken into consideration, the polarity reversal of the heating voltage can be executed at a more appropriate cycle. ..

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

-In each embodiment, a 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. Further, all the terminals to which the heating voltage is applied may be different from the terminals to which the drive voltage is applied.

-In each embodiment, the number of terminals to which the heating voltage is applied may be smaller than the number of terminals to which the drive voltage is applied. The larger the size of the dimming sheet 10, the larger the voltage drop at each of the transparent electrodes 11 and 12. Therefore, in order to prevent the drive voltage from fluctuating within the plane of the dimming sheet 10, the dimming device has three or more terminals on the transparent electrodes 11 and 12, and even if the drive voltage is applied from each terminal. Good. According to this, the voltage drop at each of the transparent electrodes 11 and 12 can be suppressed.

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

-The transparent electrode for heating the liquid crystal molecules may include an electrode located on the low temperature side with respect to the liquid crystal molecules among the first transparent electrode 11 and the second transparent electrode 12. For example, in a cold region, when the dimming sheet 10 is installed in a window that separates the room from the outside air, the transparent electrode for heating the liquid crystal molecules is an electrode located on the outside air side with respect to the liquid crystal molecules. May include. According to this configuration, the heating time for making the polarization direction of the liquid crystal molecules 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, the side of the first transparent electrode 11 with respect to the liquid crystal molecules may have a relatively low temperature. Even if the temperature of the second transparent electrode 12 with respect to the liquid crystal molecules is relatively low, 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 by an external device such as an input unit 27 or an operation unit 42, and receives at least one of the first transparent electrode 11 and the second transparent electrode 12. The configuration may be such that the heating voltage is applied. In this modified example, the electrode located on the low temperature side with respect to the liquid crystal molecules can function as a heating source in accordance with changes in the environment in which the dimming device is placed.

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

Q1 to Q6 ... Switch, SIGD1 ... 1st output level, SIGD2 ... 2nd output level, SIGE ... Drive permission signal, SIGH ... Heating start signal, SIGL ... Heating end signal, SIGS ... Switching signal, SIGX ... Inversion control signal, T0 ... Elapsed time, TH ... Heating time, V0 ... Reference level, VH, VL ... Drive level, VMH ... High level, VML ... Low level, 10 ... Dimming sheet, 11 ... First transparent electrode, 11P1, 11P2 ... First Terminal, 12 ... 2nd transparent electrode, 12P1, 12P2 ... 2nd terminal, 13 ... Dimming layer, 14, 15 ... Alignment film, 20 ... Drive device, 21 ... Power supply, 22 ... Protection circuit, 23 ... Boost circuit, 24 ... drive circuit, 25 ... voltage generation circuit, 26 ... timing control circuit, 27 ... input unit, 31 ... timer circuit, 32 ... heater power supply, 33 ... switching circuit, 41 ... measurement circuit, 42 ... operation unit.

Claims (7)

Dimming sheet and
A drive device for driving the dimming sheet and
The dimming sheet is
A first transparent electrode with a first terminal and
A second transparent electrode with multiple second terminals,
A liquid crystal molecule located between the first transparent electrode and the second transparent electrode is provided.
The drive device
The application of a heating voltage between the second terminals and the first terminal and the second terminal so as to change the polarization direction of the liquid crystal molecules while the liquid crystal molecules are heated by the second transparent electrode. A dimmer equipped with a drive unit that applies a drive voltage to the space. The dimming device according to claim 1, wherein the driving unit reverses the polarity of the heating voltage during a period in which the driving voltage is applied and the heating voltage is applied at the same time. The dimming device according to claim 2, wherein the driving unit reverses the polarity of the heating voltage at predetermined intervals. The dimming device according to any one of claims 1 to 3, wherein the drive unit switches between application of the heating voltage and application of the drive voltage. The adjustment according to claim 4, wherein the drive unit applies the heating voltage between the second terminals prior to the application of the drive voltage until a predetermined time elapses after the power is turned on to the drive device. Optical device. The temperature of the dimming sheet when the polarization direction of the liquid crystal molecules follows the driving voltage is a predetermined driveable temperature.
The drive unit
A measuring unit for measuring the temperature of the dimming sheet is provided.
When the measured value of the measuring unit is lower than the driveable temperature, the application of the heating voltage is allowed and the application of the driving voltage is prohibited, and when the measured value of the measuring unit is the driveable temperature. The dimming device according to claim 4 or 5, wherein the application of the heating voltage is prohibited and the application of the drive voltage is allowed. It is a driving method of the dimming sheet that drives the dimming sheet.
The dimming sheet is
A first transparent electrode with a first terminal and
A second transparent electrode with multiple second terminals,
A liquid crystal molecule located between the first transparent electrode and the second transparent electrode is provided.
The application of a heating voltage between the second terminals and the first terminal and the second terminal so as to change the polarization direction of the liquid crystal molecules while the liquid crystal molecules are heated by the second transparent electrode. A method of driving a dimming sheet that reverses the polarity of the heating voltage during the period in which the drive voltage is applied to the space at the same time and is applied at the same time.