Dimming device, driving device for dimming device, driving method for dimming device

Abstract

To improve the dimming and heating quality of dimming devices. [Solution] The dimming device 10 comprises a liquid crystal layer 13, a first transparent conductive film 11 disposed on one side of the liquid crystal layer 13 in the stacking direction, and a second transparent conductive film 12 disposed on the opposite side of the liquid crystal layer 13 in the stacking direction. The drive device 20 generates a plurality of drive voltages to be applied to the plurality of terminals in the first terminal group and a plurality of drive voltages to be applied to the plurality of terminals in the second terminal group, such that a predetermined current flows between the plurality of terminals in the first terminal group of the first transparent conductive film 11, a predetermined current flows between the plurality of terminals in the second terminal group of the second transparent conductive film 12, and the distribution of the voltage difference between the first transparent conductive film 11 and the second transparent conductive film 12 is a predetermined distribution.

Description

Technical Field

[0001] The present disclosure relates to a dimming device using liquid crystal technology, a driving device for a dimming device, and a driving method for a dimming device.

Background Art

[0002] In recent years, research and development on using transparent displays for the displays of in-vehicle infotainment devices has been underway. For example, research and development on transparent displays of a type attached to headrests and a flip-down type that descends from the ceiling are underway. By installing a dimming sheet (also referred to as a dimming film or a dimming device) on the transparent display, the transparent display can be provided with a function of adjusting transparency. In addition, a dimming sheet may be installed on the window glass of a vehicle to ensure privacy or adjust the amount of light entering the vehicle.

[0003] The dimming sheet sandwiches a liquid crystal layer between transparent electrodes, and by changing the voltage applied between the transparent electrodes, the orientation of liquid crystal molecules is changed to control the light transmittance. When the dimming sheet is used in a low-temperature environment such as winter, the response speed of the liquid crystal molecules suddenly becomes slow, and it takes a long time to switch from transmission to non-transmission or from non-transmission to transmission. For example, a dimming sheet that switches in less than 1 second in a normal temperature environment may take 15 minutes or more to switch in an environment of -20°C.

[0004] In Patent Document 1, a method of heating liquid crystal molecules by passing an electric current through the transparent electrodes of a dimming sheet to generate heat has been proposed. In the first control method disclosed in Patent Document 1, since the heating operation and the dimming operation are separated, even if the heating effect is sufficient, there is a possibility that the liquid crystal molecules cool down after a lapse of time when entering the dimming operation, and return to the original slow switching state. In the second control method disclosed in Patent Document 1, the heat generation operation and the dimming operation are performed simultaneously, but since only one of the transparent electrodes is heated, the heating effect is reduced. In addition, since the in-plane potential difference during the dimming operation is non-uniform, display unevenness and flicker are likely to occur.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-194086 [Overview of the project] [Problems that the invention aims to solve]

[0006] This disclosure is made in light of these circumstances and aims to provide a technology that improves the dimming and heating quality of dimming devices. [Means for solving the problem]

[0007] To solve the above problems, a dimming device according to one embodiment of the present disclosure comprises a dimming device and a drive device for driving the dimming device. The dimming device comprises a liquid crystal layer, a first transparent conductive film disposed on one surface of the liquid crystal layer in the stacking direction, and a second transparent conductive film disposed on the opposite surface of the liquid crystal layer in the stacking direction. The first transparent conductive film comprises a first terminal group including a plurality of terminals located on its outer periphery. The second transparent conductive film comprises a second terminal group on its outer periphery, including a plurality of terminals located at positions corresponding to the stacking direction of the plurality of terminals included in the first terminal group. The drive device generates a plurality of drive voltages to be applied to the plurality of terminals included in the first terminal group and a plurality of drive voltages to be applied to the plurality of terminals included in the second terminal group, such that a predetermined current flows between the plurality of terminals included in the first terminal group, a predetermined current flows between the plurality of terminals included in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is a predetermined distribution. [Effects of the Invention]

[0008] According to this disclosure, the quality of dimming and heating of dimming devices can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example configuration 1 of a dimming device according to an embodiment. [Figure 2] Figure 1 is an exploded perspective view of the first transparent conductive film, liquid crystal layer, and second transparent conductive film. [Figure 3] This figure shows an example configuration 2 of a dimming device according to an embodiment. [Figure 4] Figure 3 is an exploded perspective view of the first transparent conductive film, liquid crystal layer, and second transparent conductive film. [Figure 5] This figure shows an example of the configuration of a drive device according to an embodiment. [Figure 6] This figure shows waveform images of the first timing pulse signal and the second timing pulse signal. [Figure 7] This figure shows an example configuration of the first output section for supplying a first drive voltage to the first terminal section. [Figure 8] This figure shows specific examples of voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device during heating, and the voltage distribution in the planar direction of the dimming device during dimming drive, in relation to a comparative example. [Figure 9] This figure shows the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed, according to specific example 1 of the embodiment. [Figure 10] This figure shows a specific example of the embodiment 2, illustrating the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed. [Figure 11] This figure shows the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed, according to specific example 3 of the embodiment. [Figure 12]This figure shows the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed, according to specific example 4 of the embodiment. [Figure 13] This figure shows a specific example of the embodiment 5, illustrating the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed. [Figure 14] This figure shows a specific example of the embodiment 6, illustrating the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed. [Figure 15] This figure shows a specific example of the embodiment 7, illustrating the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed. [Figure 16] This figure shows a specific example of the embodiment 8, illustrating the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed. [Figure 17] This figure shows a specific example of the embodiment 9, illustrating the voltage patterns applied to the first, second, third, and fourth terminals, the voltage distribution in the planar direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and a screen image of the transparent display on which the dimming device is installed. [Figure 18]FIG. showing the voltage pattern applied to the first terminal portion, the second terminal portion, the third terminal portion, and the fourth terminal portion, the voltage distribution in the plane direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and the screen image of the transmissive display on which the dimming device is installed according to Specific Example 10 of the embodiment. [Figure 19] FIG. showing the voltage pattern applied to the first terminal portion, the second terminal portion, the third terminal portion, and the fourth terminal portion, the voltage distribution in the plane direction of the dimming device, the voltage-transmittance characteristics of the liquid crystal layer, and the screen image of the transmissive display on which the dimming device is installed according to Specific Example 11 of the embodiment. [Figure 20] FIG. showing the driving voltage applied to the first terminal portion - the eighth terminal portion and the screen image of the transmissive display on which the dimming device is installed according to Specific Example 12 of the embodiment. [Figure 21] FIG. showing the driving voltage applied to the first terminal portion - the eighth terminal portion and the screen image of the transmissive display on which the dimming device is installed according to Specific Example 13 of the embodiment. [Figure 22] FIG. showing the driving voltage applied to the first terminal portion - the eighth terminal portion and the screen image of the transmissive display on which the dimming device is installed according to Specific Example 14 of the embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0010] FIG. 1 is a diagram showing Configuration Example 1 of the dimming device 1 according to the embodiment. The dimming device 1 includes a dimming device 10 and a driving device 20 that drives the dimming device 10. The dimming device 10 includes a second transparent conductive film 12, a liquid crystal layer 13, and a first transparent conductive film 11 in order from the bottom in the stacking direction.

[0011] The liquid crystal layer 13 holds liquid crystal molecules with a polymer network having a three-dimensional mesh structure. The first transparent conductive film 11 is placed on one side of the liquid crystal layer 13 in the stacking direction (the upper side in Figure 1). The second transparent conductive film 12 is placed on the opposite side of the liquid crystal layer 13 in the stacking direction (the lower side in Figure 1). For example, ITO (Indium Tin Oxide) is used for the first transparent conductive film 11 and the second transparent conductive film 12. However, ZnO, SnO2, In2O3, etc. may be used instead of ITO.

[0012] The first transparent conductive film 11 includes a first terminal portion 111 and a second terminal portion 112. The second transparent conductive film 12 includes a third terminal portion 121 and a fourth terminal portion 122. The first terminal portion 111, the second terminal portion 112, the third terminal portion 121, and the fourth terminal portion 122 are each wired and connected to the drive device 20.

[0013] Figure 2 is an exploded perspective view of the first transparent conductive film 11, liquid crystal layer 13, and second transparent conductive film 12 shown in Figure 1. The first terminal portion 111 is located in a first region on the outer periphery of the first transparent conductive film 11. The second terminal portion 112 is located in a second region on the outer periphery of the first transparent conductive film 11, opposite to the first terminal portion 111. In the example shown in Figure 2, the first region of the first transparent conductive film 11 is one short side region of the first transparent conductive film 11 (the lower side in Figure 2), and the second region of the first transparent conductive film 11 is the other short side region of the first transparent conductive film 11 (the upper side in Figure 2).

[0014] The third terminal portion 121 is located in a third region on the outer periphery of the second transparent conductive film 12, corresponding to the first region of the first transparent conductive film 11 and the lamination direction. The fourth terminal portion 122 is located in a fourth region on the outer periphery of the second transparent conductive film 12, opposite to the third terminal portion 121. In the example shown in Figure 2, the third region of the second transparent conductive film 12 is one short side region of the second transparent conductive film 12 (the lower side in Figure 2), and the fourth region of the second transparent conductive film 12 is the other short side region of the second transparent conductive film 12 (the upper side in Figure 2).

[0015] Figure 3 is a diagram showing an example configuration 2 of the dimming device 1 according to an embodiment. Figure 4 is an exploded perspective view of the first transparent conductive film 11, liquid crystal layer 13, and second transparent conductive film 12 of Figure 3. Example configuration 2 is an example in which FPCs (Flexible Printed Circuits) are used for the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122. The first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, which use FPCs, each have a first connector 111a, a second connector 112a, a third connector 121a, and a fourth connector 122a, respectively.

[0016] The first terminal portion 111 and the second terminal portion 112, which use FPCs, are crimped onto the region of the first transparent conductive film 11 where the first terminal portion 111 and the second terminal portion 112 are to be placed. Similarly, the third terminal portion 121 and the fourth terminal portion 122, which use FPCs, are crimped onto the region of the second transparent conductive film 12 where the third terminal portion 121 and the fourth terminal portion 122 are to be placed.

[0017] In the regions of the second transparent conductive film 12 located on the opposite side in the lamination direction from the regions of the first terminal portion 111 and the second terminal portion 112 that are pressed onto the first transparent conductive film 11, the third terminal portion 121 and the fourth terminal portion 122 are not arranged. Similarly, in the regions of the first transparent conductive film 11 located on the opposite side in the lamination direction from the regions of the third terminal portion 121 and the fourth terminal portion 122 that are pressed onto the second transparent conductive film 12, the first terminal portion 111 and the second terminal portion 112 are not arranged.

[0018] As shown in Figure 4, the first terminal portion 111 is positioned in the left half (shown) or right half of one short side region (lower side in Figure 4) of the first transparent conductive film 11, and the third terminal portion 121 is positioned in the right half (shown) or left half of the corresponding short side region (lower side in Figure 4) of the second transparent conductive film 12, so that the first terminal portion 111 and the third terminal portion 121 do not overlap in the stacking direction.

[0019] Similarly, so that the second terminal portion 112 and the fourth terminal portion 122 do not overlap in the stacking direction, the second terminal portion 112 is located in the right half (shown) or left half of the other short side region (upper side in Figure 4) of the first transparent conductive film 11, and the fourth terminal portion 122 is located in the left half (shown) or right half of the corresponding short side region (upper side in Figure 4) of the second transparent conductive film 12.

[0020] In this embodiment, the drive device 20 generates a first drive voltage Vd1 applied to the first terminal portion 111, a second drive voltage Vd2 applied to the second terminal portion 112, a third drive voltage Vd3 applied to the third terminal portion 121, and a fourth drive voltage Vd4 applied to the fourth terminal portion 122, such that a predetermined current flows between the first terminal portion 111 and the second terminal portion 112, a predetermined current flows between the third terminal portion 121 and the fourth terminal portion 122, and the voltage difference distribution between the first transparent conductive film 11 and the second transparent conductive film 12 has a predetermined distribution.

[0021] When the dimming device 10 is to be dimmed uniformly across the entire surface, the drive unit 20 generates a first drive voltage Vd1, a second drive voltage Vd2, a third drive voltage Vd3, and a fourth drive voltage Vd4 so that the distribution of the voltage difference between the first transparent conductive film 11 and the second transparent conductive film 12 is uniform. When the dimming device 10 is to be dimmed in a gradient, the drive unit 20 sets the voltage difference between the first drive voltage Vd1 and the third drive voltage Vd3 and the voltage difference between the second drive voltage Vd2 and the fourth drive voltage Vd4 to different values ​​so that the distribution of the voltage difference between the first transparent conductive film 11 and the second transparent conductive film 12 is gradient. Specific examples of dimming control will be described later.

[0022] Figure 5 shows an example of the configuration of a drive device 20 according to an embodiment. The drive device 20 includes an input unit 21, a power supply unit 22, a control coefficient setting unit 23, a timing control circuit 24, a timer circuit 25, a voltage generation circuit 26, a drive circuit 27, and an output voltage switching conversion unit 28.

[0023] The input unit 21 receives ambient temperature measured by a temperature sensor (not shown) and operation signals based on user operations input to the operation unit (not shown). The timer circuit 25 manages the heating time of the liquid crystal layer 13 based on the ambient temperature and operation signals input from the input unit 21 and sets the heating completion timing in the voltage generation circuit 26.

[0024] The operation signals based on user operation include dimming settings. If an illuminance sensor (not shown) is provided, the input unit 21 also accepts the illuminance measured by the illuminance sensor. The input unit 21 determines the transmittance of the liquid crystal layer 13 based on at least one of the dimming settings based on user operation or the illuminance measured by the illuminance sensor. The input unit 21 determines the stacking direction voltage difference to be generated between the first transparent conductive film 11 and the second transparent conductive film 12 according to the determined transmittance.

[0025] The input unit 21 determines the amount of heating required to heat the liquid crystal layer 13 based on the ambient temperature measured by the temperature sensor. The input unit 21 then determines, according to the determined amount of heating, the first planar voltage difference to be generated between the first terminal portion 111 and the second terminal portion 112 of the first transparent conductive film 11, and the second planar voltage difference to be generated between the third terminal portion 121 and the fourth terminal portion 122 of the second transparent conductive film 12.

[0026] The relationship between ambient temperature, heating amount, and the voltage difference in the first and second plane directions is pre-defined into a table based on experimental or simulation results and registered in the input unit 21 beforehand.

[0027] The input unit 21 determines the values ​​of the first voltage V1, second voltage V2, third voltage V3, and fourth voltage V4 based on the determined stacking direction voltage difference, first planar direction voltage difference, and second planar direction voltage difference, and sets them in the voltage generation circuit 26.

[0028] The power supply unit 22 supplies power voltage to the voltage generation circuit 26 and the drive circuit 27. When the dimming device 1 is mounted on a vehicle, an auxiliary battery can be used for the power supply unit 22. In that case, a 12V DC voltage can be supplied from the auxiliary battery.

[0029] The voltage generation circuit 26 boosts or steps down the DC voltage supplied from the power supply unit 22 to generate the first voltage V1, second voltage V2, third voltage V3, and fourth voltage V4 set by the drive unit 20. The voltage generation circuit 26 outputs the generated first voltage V1, second voltage V2, third voltage V3, and fourth voltage V4 to the output voltage switching conversion unit 28. The voltage generation circuit 26 includes two or four DC / DC converters capable of boosting or stepping down the DC voltage supplied from the power supply unit 22. In the case where only DC voltages lower than the DC voltage supplied from the power supply unit 22 are used, a boost chopper dedicated to boosting may be used as the DC / DC converter.

[0030] The timing control circuit 24 generates a first timing pulse signal W1 and a second timing pulse signal W2 and supplies them to the drive circuit 27. The timing control circuit 24 generates a heating current direction switching signal Vs and supplies it to the output voltage switching conversion unit 28. The heating current direction switching signal Vs is a signal that sets whether the direction of heating current flow in the first transparent conductive film 11 or the second transparent conductive film 12 is periodically switched or fixed in one direction. In the case of periodic switching, the period during which current flows from the first terminal 111 to the second terminal 112 and the period during which current flows from the second terminal 112 to the first terminal 111 are periodically switched. Whether to periodically switch the heating current direction or fix it in one direction is set in the timing control circuit 24 by the control coefficient setting unit 23.

[0031] Figure 6 shows waveform images of the first timing pulse signal W1 and the second timing pulse signal W2. The second timing pulse signal W2 is the inverse phase signal (a signal with a 180° phase shift) of the first timing pulse signal W1. The periods of the first timing pulse signal W1 and the second timing pulse signal W2 are set by the control coefficient setting unit 23 to the timing control circuit 24.

[0032] The drive circuit 27 generates a first basic drive signal S1(a,b), a second basic drive signal S2(a,b), a third basic drive signal S3(a,b), and a fourth basic drive signal S4(a,b) based on the DC voltage supplied from the power supply unit 22, or a DC voltage obtained by stepping down the DC voltage supplied from the power supply unit 22, and the first timing pulse signal W1 and the second timing pulse signal W2 supplied from the timing control circuit 24, and supplies them to the output voltage switching conversion unit 28.

[0033] The output voltage switching conversion unit 28 includes four output units for supplying drive voltages to the first terminal unit 111, the second terminal unit 112, the third terminal unit 121, and the fourth terminal unit 122, respectively.

[0034] Figure 7 shows an example configuration of a first output unit for supplying a first drive voltage Vd1 to the first terminal unit 111. The first output unit includes a first switching unit 281, a second switching unit 282, a first level conversion unit 283, a second level conversion unit 284, a first switching element Qa, and a second switching element Qb.

[0035] The first switching unit 281 refers to the heating current direction switching signal Vs and selects and outputs either the first voltage V1 or the second voltage V2. The second switching unit 282 refers to the heating current direction switching signal Vs and selects and outputs either the third voltage V3 or the fourth voltage V4.

[0036] A first switching element Qa and a second switching element Qb are connected in series between the output potential of the first switching unit 281 and the output potential of the second switching unit 282. In the example shown in Figure 7, a P-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used for the first switching element Qa, and an N-channel MOSFET is used for the second switching element Qb.

[0037] The source terminal of the first switching element Qa is connected to the output potential of the first switching unit 281, the source terminal of the second switching element Qb is connected to the output potential of the second switching unit 282, and the connection point between the drain terminal of the first switching element Qa and the drain terminal of the second switching element Qb is connected to the first terminal unit 111.

[0038] The first level conversion unit 283 converts the voltage level of the first basic drive signal S1(a) into the gate voltage required to turn the first switching element Qa on or off, and applies it to the gate terminal of the first switching element Qa. The second level conversion unit 284 converts the voltage level of the first basic drive signal S1(b) which is in the opposite phase into the gate voltage required to turn the second switching element Qb on or off, and applies it to the gate terminal of the second switching element Qb.

[0039] The first switching element Qa and the second switching element Qb operate complementaryly. When the first switching element Qa is on and the second switching element Qb is off, the first voltage V1 or second voltage V2 selected by the first switching unit 281 is applied to the first terminal unit 111 as the first drive voltage Vd1. When the first switching element Qa is off and the second switching element Qb is on, the third voltage V3 or fourth voltage V4 selected by the second switching unit 282 is applied to the first terminal unit 111 as the first drive voltage Vd1.

[0040] The configuration of the second output unit for supplying a second drive voltage Vd2 to the second terminal unit 112, the third output unit for supplying a third drive voltage Vd3 to the third terminal unit 121, and the fourth output unit for supplying a fourth drive voltage Vd4 to the fourth terminal unit 122 is the same as the configuration of the first output unit.

[0041] The heating voltage of the first transparent conductive film 11 is defined by the first planar voltage difference (Vd1-Vd2) between the first drive voltage Vd1 and the second drive voltage Vd2, and the heating voltage of the second transparent conductive film 12 is defined by the second planar voltage difference (Vd3-Vd4) between the third drive voltage Vd3 and the fourth drive voltage Vd4. In this embodiment, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are set to equal values.

[0042] The sign of the heating voltage indicates the direction of the current. When the value of the first planar voltage difference (Vd1-Vd2) is positive, it means that current flows from the first terminal 111 to which the first drive voltage Vd1 is applied, to the second terminal 112 to which the second drive voltage Vd2 is applied. The larger the first planar voltage difference (Vd1-Vd2), the greater the current flowing through the first transparent conductive film 11, and the greater the amount of heat generated by the first transparent conductive film 11. The same applies to the second planar voltage difference (Vd3-Vd4).

[0043] The dimming voltage is defined by the first stacking direction voltage difference (Vd1-Vd3) between the first drive voltage Vd1 and the third drive voltage Vd3, and the second stacking direction voltage difference (Vd2-Vd4) between the second drive voltage Vd2 and the fourth drive voltage Vd4. When the dimming of the dimming device 10 is performed uniformly across the entire surface, the first stacking direction voltage difference (Vd1-Vd3) and the second stacking direction voltage difference (Vd2-Vd4) are set to equal values.

[0044] The sign of the dimming voltage indicates the direction of voltage application. The larger the voltage difference in the first stacking direction (Vd1-Vd3), the greater the voltage applied to the liquid crystal layer 13, and the higher the transmittance in the normal type dimming device 10. The same applies to the voltage difference in the second stacking direction (Vd2-Vd4).

[0045] In a normal type dimming device 10, the lower the voltage applied to the liquid crystal layer 13, the more opaque it becomes, and the higher the voltage applied to the liquid crystal layer 13, the more transparent it becomes. Conversely, in a reverse type dimming device 10, the lower the voltage applied to the liquid crystal layer 13, the more transparent it becomes, and the higher the voltage applied to the liquid crystal layer 13, the more opaque it becomes. In the following embodiment, we will assume an example using a normal type dimming device 10.

[0046] For example, when the first drive voltage Vd1 = +50V, the second drive voltage Vd2 = +45V, the third drive voltage Vd3 = +20V, and the fourth drive voltage Vd4 = +15V, the heating voltage will be +5V and the dimming voltage will be +30V.

[0047] Figure 8 shows specific examples of voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122 in a comparative example, as well as the voltage distribution in the planar direction x of the dimming device 10 during heating and the voltage distribution in the planar direction x of the dimming device 10 during dimming drive.

[0048] The drive unit 20 applies a first drive voltage Vd1 to the first terminal 111. The high level (High(1)) of the first drive voltage Vd1 is set to +40V, and the low level (Low(1)) is set to +20V. The drive unit 20 applies a second drive voltage Vd2 to the second terminal 112. The high level (High(2)) of the second drive voltage Vd2 is set to +40V, and the low level (Low(2)) is set to +20V. The drive unit 20 applies a third drive voltage Vd3 to the third terminal 121. The high level (High(3)) of the third drive voltage Vd3 is set to +40V, and the low level (Low(3)) is set to +20V. The drive unit 20 applies a fourth drive voltage Vd4 to the fourth terminal 122. The high level (High(4)) of the fourth drive voltage Vd4 is set to +40V, and the low level (Low(4)) is set to +20V.

[0049] In the comparative example, the heating time and the dimming drive time are set separately. During the heating period t1, the drive device 20 sets the first drive voltage Vd1 to high level (1), the second drive voltage Vd2 to low level (2), the third drive voltage Vd3 to high level (3), and the fourth drive voltage Vd4 to low level (4).

[0050] The first planar voltage difference (Vd1-Vd2) becomes 20V (=40V-20V), causing current to flow through the first transparent conductive film 11 and generating heat. The second planar voltage difference (Vd3-Vd4) also becomes 20V (=40V-20V), causing current to flow through the second transparent conductive film 12 and generating heat. The first stacking direction voltage difference (Vd1-Vd3) becomes 0V (=40V-40V), and the second stacking direction voltage difference (Vd2-Vd4) also becomes 0V (=20V-20V), resulting in the liquid crystal layer 13 being in a light-shielding state.

[0051] During the dimming drive period, the drive device 20 generates the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 as rectangular wave voltages of the same amplitude (20V). When driving the liquid crystal layer 13, applying rectangular wave voltages instead of a constant voltage periodically resets the orientation of the liquid crystal molecules, which helps to suppress the degradation of the liquid crystal molecules.

[0052] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 in phase, and the third drive voltage Vd3 and the fourth drive voltage Vd4 in phase. The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 pair and the third drive voltage Vd3 and the fourth drive voltage Vd4 pair in opposite phase.

[0053] The first planar voltage difference (Vd1-Vd2) is always 0V, no current flows between the first terminal 111 and the second terminal 112, and the first transparent conductive film 11 does not generate heat. The second planar voltage difference (Vd3-Vd4) is also always 0V, no current flows between the third terminal 121 and the fourth terminal 122, and the second transparent conductive film 12 does not generate heat.

[0054] The first stacking direction voltage difference (Vd1-Vd3) is +20V (=40V-20V) in the first state (see t2) and -20V (=20V-40V) in the second state. The second stacking direction voltage difference (Vd2-Vd4) is also +20V (=40V-20V) in the first state (see t2) and -20V (=20V-40V) in the second state. The liquid crystal layer 13 transmits light with transmittance corresponding to ±20V.

[0055] In the control method of the comparative example, as described above, the heating operation and dimming operation are separated. Therefore, even if the heating effect is sufficient, once the dimming operation begins and time passes, the liquid crystal molecules may cool down and revert to the original slow switching state.

[0056] In this embodiment, heating and dimming operations are performed simultaneously. The drive device 20 generates a voltage difference within the first transparent conductive film 11 or the second transparent conductive film 12, respectively, and while flowing current through the first transparent conductive film 11 or the second transparent conductive film 12, it also generates a voltage difference between the first transparent conductive film 11 and the second transparent conductive film 12, thereby achieving heating and dimming simultaneously.

[0057] Figure 9 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 1 of the embodiment.

[0058] Specific example 1 assumes an ambient temperature of 0°C and the overall screen dimming setting is set to "bright." When the dimming setting is set to "bright," the dimming device becomes transparent. Examples of situations where the dimming setting is set to "bright" include when you want to superimpose the scenery outside the vehicle onto the transparent display screen, or when you want to see the scenery outside, during the day or at night.

[0059] In specific example 1, the heating voltage is set to +5V and the dimming voltage to ±30V. The drive unit 20 generates the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 as square wave voltages of the same amplitude (30V).

[0060] In specific example 1, the high level (High(1)) of the first drive voltage Vd1 is set to +50V, and the low level (Low(1)) is set to +20V. The high level (High(2)) of the second drive voltage Vd2 is set to +45V, and the low level (Low(2)) is set to +15V. The high level (High(3)) of the third drive voltage Vd3 is set to +50V, and the low level (Low(3)) is set to +20V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +45V, and the low level (Low(4)) is set to +15V.

[0061] The center level of the first drive voltage Vd1 is +35V, and the center level of the second drive voltage Vd2 is +30V, with the center level of the second drive voltage Vd2 shifted 5V lower than the center level of the first drive voltage Vd1. Similarly, the center level of the third drive voltage Vd3 is +35V, and the center level of the fourth drive voltage Vd4 is +30V, with the center level of the fourth drive voltage Vd4 shifted 5V lower than the center level of the third drive voltage Vd3.

[0062] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 in phase, and the third drive voltage Vd3 and the fourth drive voltage Vd4 in phase. The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 pair and the third drive voltage Vd3 and the fourth drive voltage Vd4 pair in opposite phase.

[0063] At both time t1 in the first state and time t2 in the second state of the drive pattern, the drive device 20 controls the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) to the same value. As a result, the amount of heating from the first transparent conductive film 11 to the liquid crystal layer 13 is equal to the amount of heating from the second transparent conductive film 12 to the liquid crystal layer 13.

[0064] The drive unit 20 controls the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) to increase as the ambient temperature is low and the required amount of heating increases.

[0065] At both time t1 in the first state and time t2 in the second state of the drive pattern, the drive unit 20 controls the first stacking direction voltage difference (Vd1-Vd3) and the second stacking direction voltage difference (Vd2-Vd4) to the same value. As a result, the stacking direction voltage difference at each position in the planar direction x of the dimming device 10 all becomes the same absolute value (30V in specific example 1). At time t1 in the first state, the voltage of the first transparent conductive film 11 is higher than that of the second transparent conductive film 12 (+30V), and at time t2 in the second state, the voltage of the second transparent conductive film 12 is higher than that of the first transparent conductive film 11 (-30V).

[0066] The statement that the stacking direction voltage difference at each position in the planar direction x of the dimming device 10 is the same value means that the first voltage drop line connecting the first drive voltage Vd1 of the first terminal portion 111 and the second drive voltage Vd2 of the second terminal portion 112 is parallel to the second voltage drop line connecting the third drive voltage Vd3 of the third terminal portion 121 and the fourth drive voltage Vd4 of the fourth terminal portion 122.

[0067] In this way, by switching the polarity of the voltage applied to the liquid crystal layer 13 sandwiched between the first transparent conductive film 11 and the second transparent conductive film 12 in the first and second states of the driving pattern, it is possible to prevent the orientation of the liquid crystal molecules from becoming fixed, thereby contributing to suppressing the degradation of the liquid crystal molecules.

[0068] The drive unit 20 controls the first stacking direction voltage difference (Vd1-Vd3) and the second stacking direction voltage difference (Vd2-Vd4) according to the required transmittance of the liquid crystal layer 13. In a normal type dimming device 10, the drive unit 20 controls the first stacking direction voltage difference (Vd1-Vd3) and the second stacking direction voltage difference (Vd2-Vd4) to increase as the required transmittance of the liquid crystal layer 13 increases. In a reverse type dimming device 10, the drive unit 20 controls the first stacking direction voltage difference (Vd1-Vd3) and the second stacking direction voltage difference (Vd2-Vd4) to decrease as the required transmittance of the liquid crystal layer 13 increases.

[0069] Figure 10 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 2 of the embodiment.

[0070] Specific Example 2 also assumes an ambient temperature of 0°C and a screen dimming setting of bright. In Specific Example 2, the heating voltage is set to ±5V and the dimming voltage to ±30V. The drive unit 20 generates the first drive voltage Vd1 and the fourth drive voltage Vd4 as square waves with the same amplitude (35V) and opposite phase. The drive unit 20 generates the second drive voltage Vd2 and the third drive voltage Vd3 as square waves with the same amplitude (25V) and opposite phase.

[0071] In specific example 2, the high level (High(1)) of the first drive voltage Vd1 is set to +50V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +45V, and the low level (Low(2)) is set to +20V. The high level (High(3)) of the third drive voltage Vd3 is set to +45V, and the low level (Low(3)) is set to +20V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +50V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 are all +32.5V.

[0072] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 so that they are in phase and have the same center level, and the third drive voltage Vd3 and the fourth drive voltage Vd4 so that they are in phase and have the same center level. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the second drive voltage Vd2 and the pairs of the third drive voltage Vd3 and the fourth drive voltage Vd4 so that they are out of phase.

[0073] The difference between Specific Example 2 and Specific Example 1 is whether or not the direction of the heating current is switched. In Specific Example 1, the direction of the heating current for the first transparent conductive film 11 is fixed from the first terminal portion 111 to the second terminal portion 112, regardless of whether it is time t1 in the first state of the drive pattern or time t2 in the second state. Similarly, the direction of the heating current for the second transparent conductive film 12 is fixed from the third terminal portion 121 to the fourth terminal portion 122, regardless of whether it is time t1 in the first state of the drive pattern or time t2 in the second state.

[0074] In specific example 2, the direction of the heating current for the first transparent conductive film 11 switches between time t1 in the first state of the drive pattern and time t2 in the second state of the drive pattern. At time t1 in the first state, current flows from the first terminal portion 111 to the second terminal portion 112, and at time t2 in the second state, current flows from the second terminal portion 112 to the first terminal portion 111. Similarly, the direction of the heating current for the second transparent conductive film 12 switches between time t1 in the first state of the drive pattern and time t2 in the second state of the drive pattern. At time t1 in the first state, current flows from the third terminal portion 121 to the fourth terminal portion 122, and at time t2 in the second state, current flows from the fourth terminal portion 122 to the third terminal portion 121.

[0075] Thus, in specific example 2, the direction in which the heating current flows is reversed between the first and second states of the driving pattern. By periodically switching the direction of the heating current flowing through the first transparent conductive film 11 and the second transparent conductive film 12, it is possible to suppress uneven heating of the liquid crystal layer 13 and also contribute to suppressing uneven degradation of the first transparent conductive film 11 and the second transparent conductive film 12.

[0076] Figure 11 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and a screen image of the transparent display on which the dimming device 10 is installed, according to specific example 3 of the embodiment.

[0077] Specific example 3 assumes an ambient temperature of -30°C and a screen dimming setting of bright. In Specific Example 3, the heating voltage is set to +15V and the dimming voltage to ±30V. The drive unit 20 generates the first drive voltage Vd1 and the fourth drive voltage Vd4 as square waves with the same amplitude (45V) and opposite phase. The drive unit 20 generates the second drive voltage Vd2 and the third drive voltage Vd3 as square waves with the same amplitude (15V) and opposite phase.

[0078] In specific example 3, the high level (High(1)) of the first drive voltage Vd1 is set to +60V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +45V, and the low level (Low(2)) is set to +30V. The high level (High(3)) of the third drive voltage Vd3 is set to +45V, and the low level (Low(3)) is set to +30V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +60V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, second drive voltage Vd2, third drive voltage Vd3, and fourth drive voltage Vd4 are all +37.5V.

[0079] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 so that they are in phase and have the same center level, and the third drive voltage Vd3 and the fourth drive voltage Vd4 so that they are in phase and have the same center level. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the second drive voltage Vd2 and the pairs of the third drive voltage Vd3 and the fourth drive voltage Vd4 so that they are out of phase.

[0080] The difference between Specific Example 2 and Specific Example 3 is that Specific Example 3 requires a larger amount of heating. In Specific Example 2, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are ±5V, while in Specific Example 3, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are ±15V. As the voltage difference increases, the current flowing through the first transparent conductive film 11 and the second transparent conductive film 12 increases, and the amount of heat generated increases. Considering the voltage distribution in the planar direction x of the dimming device 10, the slope of the voltage in the planar direction x is greater in Specific Example 3.

[0081] The voltage difference in the first stacking direction (Vd1-Vd3) and the voltage difference in the second stacking direction (Vd2-Vd4) are the same in Specific Example 2 and Specific Example 3, and the transmittance of the liquid crystal layer 13 is the same in Specific Example 2 and Specific Example 3.

[0082] Figure 12 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 4 of the embodiment.

[0083] Specific example 4 assumes an ambient temperature of 25°C and a screen dimming setting of bright. In Specific Example 4, there is no heating and the dimming voltage is set to ±30V. The drive device 20 generates the first drive voltage Vd1, second drive voltage Vd2, third drive voltage Vd3, and fourth drive voltage Vd4 as square wave voltages of the same amplitude (30V).

[0084] In specific example 4, the high level (High(1)) of the first drive voltage Vd1 is set to +45V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +45V, and the low level (Low(2)) is set to +15V. The high level (High(3)) of the third drive voltage Vd3 is set to +45V, and the low level (Low(3)) is set to +15V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +45V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, second drive voltage Vd2, third drive voltage Vd3, and fourth drive voltage Vd4 are all +30V.

[0085] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 to be the same, and the third drive voltage Vd3 and the fourth drive voltage Vd4 to be the same. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the second drive voltage Vd2 and the pairs of the third drive voltage Vd3 and the fourth drive voltage Vd4 to be out of phase.

[0086] At both time t1 in the first state and time t2 in the second state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are 0V. Therefore, no current flows between the first terminal portion 111 and the second terminal portion 112 of the first transparent conductive film 11, and between the third terminal portion 121 and the fourth terminal portion 122 of the second transparent conductive film 12, and the first transparent conductive film 11 and the second transparent conductive film 12 do not generate heat.

[0087] At both time t1 in the first state and time t2 in the second state of the driving pattern, the voltage difference in the stacking direction at each position x in the planar direction of the dimming device 10 is the same absolute value (30V in specific example 4). At time t1 in the first state, the voltage of the first transparent conductive film 11 is higher than that of the second transparent conductive film 12 (+30V), and at time t2 in the second state, the voltage of the second transparent conductive film 12 is higher than that of the first transparent conductive film 11 (-30V).

[0088] Figure 13 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and a screen image of the transparent display on which the dimming device 10 is installed, according to specific example 5 of the embodiment.

[0089] Specific example 5 assumes an ambient temperature of 25°C and a screen dimming setting of "dim". When the dimming setting is "dim", the dimming device becomes opaque. Examples of situations where the dimming setting is "dim" include when the setting sun in the evening is too bright and the image displayed on the transparent display is difficult to see, or when you don't want pedestrians outside the vehicle to see the image displayed on the transparent display.

[0090] In specific example 5, heating is disabled and the dimming voltage is set to 0V. The drive unit 20 generates the first drive voltage Vd1, second drive voltage Vd2, third drive voltage Vd3, and fourth drive voltage Vd4 at the same constant voltage level (15V).

[0091] At both time t1 in the first state and time t2 in the second state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are 0V. Therefore, no current flows between the first terminal portion 111 and the second terminal portion 112 of the first transparent conductive film 11, and between the third terminal portion 121 and the fourth terminal portion 122 of the second transparent conductive film 12, and the first transparent conductive film 11 and the second transparent conductive film 12 do not generate heat.

[0092] At time t1 of the first state and time t2 of the second state of the driving pattern, the stacking direction voltage difference at each position x in the planar direction of the dimming device 10 is all 0V, and in the normal type dimming device 10, the liquid crystal layer 13 is opaque.

[0093] Figure 14 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and a screen image of the transparent display on which the dimming device 10 is installed, according to specific example 6 of the embodiment.

[0094] Specific example 6 assumes an ambient temperature of 0°C and a dimming setting for the entire screen. In Specific Example 6, the heating voltage is set to ±5V and the dimming voltage to 0V. The drive device 20 generates the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 as square wave voltages of the same amplitude (5V).

[0095] In specific example 6, the high level (High(1)) of the first drive voltage Vd1 is set to +20V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +20V, and the low level (Low(2)) is set to +15V. The high level (High(3)) of the third drive voltage Vd3 is set to +20V, and the low level (Low(3)) is set to +15V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +20V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 are all +17.5V.

[0096] The drive unit 20 generates the first drive voltage Vd1 and the third drive voltage Vd3 to be the same, and the second drive voltage Vd2 and the fourth drive voltage Vd4 to be the same. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the third drive voltage Vd3 and the pairs of the second drive voltage Vd2 and the fourth drive voltage Vd4 to be out of phase.

[0097] At time t1 in the first state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are +5V, and at time t2 in the second state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are -5V. In both states, heat equivalent to the current flowing with a voltage difference of 5V is generated in each of the first transparent conductive film 11 and the second transparent conductive film 12.

[0098] At time t1 of the first state and time t2 of the second state of the driving pattern, the stacking direction voltage difference at each position x in the planar direction of the dimming device 10 is all 0V, and in the normal type dimming device 10, the liquid crystal layer 13 is opaque.

[0099] Figure 15 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 7 of the embodiment.

[0100] Specific example 7 assumes an ambient temperature of -30°C and a dimming setting for the entire screen. In Specific Example 7, the heating voltage is set to ±15V and the dimming voltage to 0V. The drive unit 20 generates the first drive voltage Vd1, second drive voltage Vd2, third drive voltage Vd3, and fourth drive voltage Vd4 as square wave voltages of the same amplitude (15V).

[0101] In specific example 7, the high level (High(1)) of the first drive voltage Vd1 is set to +30V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +30V, and the low level (Low(2)) is set to +15V. The high level (High(3)) of the third drive voltage Vd3 is set to +30V, and the low level (Low(3)) is set to +15V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +30V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 are all +22.5V.

[0102] The drive unit 20 generates the first drive voltage Vd1 and the third drive voltage Vd3 to be the same, and the second drive voltage Vd2 and the fourth drive voltage Vd4 to be the same. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the third drive voltage Vd3 and the pairs of the second drive voltage Vd2 and the fourth drive voltage Vd4 to be out of phase.

[0103] The difference between Specific Example 6 and Specific Example 7 is that Specific Example 7 requires a larger amount of heating. In Specific Example 6, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are ±5V, while in Specific Example 7, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are ±15V. As the voltage difference increases, the current flowing through the first transparent conductive film 11 and the second transparent conductive film 12 increases, and the amount of heat generated increases. Considering the voltage distribution in the planar direction x of the dimming device 10, the slope of the voltage in the planar direction x is greater in Specific Example 7.

[0104] At time t1 of the first state and time t2 of the second state of the driving pattern, the stacking direction voltage difference at each position x in the planar direction of the dimming device 10 is all 0V, and in the normal type dimming device 10, the liquid crystal layer 13 is opaque.

[0105] Figure 16 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 8 of the embodiment.

[0106] Specific example 8 assumes an ambient temperature of 25°C and a screen dimming setting set to the middle. When the dimming setting is set to the middle, the dimming device becomes semi-transparent. An example of when the dimming setting is set to the middle is when, during the daytime, you want to superimpose an image displayed on a transparent display with the outside scenery, but the outside is too bright and the image is difficult to see.

[0107] In specific example 8, heating is disabled and the dimming voltage is set to ±15V. The drive unit 20 generates the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 as square wave voltages of the same amplitude (15V).

[0108] In specific example 8, the high level (High(1)) of the first drive voltage Vd1 is set to +30V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +30V, and the low level (Low(2)) is set to +15V. The high level (High(3)) of the third drive voltage Vd3 is set to +30V, and the low level (Low(3)) is set to +15V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +30V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 are all +22.5V.

[0109] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 to be the same, and the third drive voltage Vd3 and the fourth drive voltage Vd4 to be the same. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the second drive voltage Vd2 and the pairs of the third drive voltage Vd3 and the fourth drive voltage Vd4 to be out of phase.

[0110] At both time t1 in the first state and time t2 in the second state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are 0V. Therefore, no current flows between the first terminal portion 111 and the second terminal portion 112 of the first transparent conductive film 11, and between the third terminal portion 121 and the fourth terminal portion 122 of the second transparent conductive film 12, and the first transparent conductive film 11 and the second transparent conductive film 12 do not generate heat.

[0111] At both time t1 in the first state and time t2 in the second state of the driving pattern, the voltage difference in the stacking direction at each position x in the planar direction of the dimming device 10 is the same absolute value (15V in specific example 8). At time t1 in the first state, the voltage of the first transparent conductive film 11 is higher than that of the second transparent conductive film 12 (+15V), and at time t2 in the second state, the voltage of the second transparent conductive film 12 is higher than that of the first transparent conductive film 11 (-15V). The liquid crystal layer 13 is semi-transparent.

[0112] Figure 17 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and a screen image of the transparent display on which the dimming device 10 is installed, according to specific example 9 of the embodiment.

[0113] In specific example 9, it is assumed that the ambient temperature is 0°C and the overall screen dimming setting is set to the middle. In specific example 9, the heating voltage is set to ±5V and the dimming voltage is set to ±15V. The drive unit 20 generates the first drive voltage Vd1 and the fourth drive voltage Vd4 as square waves with the same amplitude (20V) and opposite phase. The drive unit 20 generates the second drive voltage Vd2 and the third drive voltage Vd3 as square waves with the same amplitude (10V) and opposite phase.

[0114] In specific example 9, the high level (High(1)) of the first drive voltage Vd1 is set to +35V, and the low level (Low(1)) is set to +15V. The high level (High(2)) of the second drive voltage Vd2 is set to +30V, and the low level (Low(2)) is set to +20V. The high level (High(3)) of the third drive voltage Vd3 is set to +30V, and the low level (Low(3)) is set to +20V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +35V, and the low level (Low(4)) is set to +15V. The center levels of the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 are all +25V.

[0115] The drive unit 20 generates the first drive voltage Vd1 and the second drive voltage Vd2 so that they are in phase and have the same center level, and the third drive voltage Vd3 and the fourth drive voltage Vd4 so that they are in phase and have the same center level. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the second drive voltage Vd2 and the pairs of the third drive voltage Vd3 and the fourth drive voltage Vd4 so that they are out of phase.

[0116] At time t1 in the first state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are +5V, and at time t2 in the second state of the drive pattern, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are -5V. In both states, heat equivalent to the current flowing with a voltage difference of 5V is generated in each of the first transparent conductive film 11 and the second transparent conductive film 12.

[0117] At both time t1 in the first state and time t2 in the second state of the driving pattern, the voltage difference in the stacking direction at each position x in the planar direction of the dimming device 10 is the same absolute value (15V in specific example 9). At time t1 in the first state, the voltage of the first transparent conductive film 11 is higher than that of the second transparent conductive film 12 (+15V), and at time t2 in the second state, the voltage of the second transparent conductive film 12 is higher than that of the first transparent conductive film 11 (-15V). The liquid crystal layer 13 is semi-transparent.

[0118] Figure 18 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 10 of the embodiment.

[0119] In specific example 10, the ambient temperature is assumed to be -30°C and the overall screen dimming setting is set to the middle. In specific example 10, the heating voltage is set to ±15V and the dimming voltage is set to ±15V. The drive unit 20 generates the first drive voltage Vd1 and the fourth drive voltage Vd4 as square waves with the same amplitude (30V) and opposite phase. The drive unit 20 generates the second drive voltage Vd2 and the third drive voltage Vd3 as constant voltages of the same level (30V).

[0120] In specific example 10, the high level (High(1)) of the first drive voltage Vd1 is set to +45V, and the low level (Low(1)) is set to +15V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +45V, and the low level (Low(4)) is set to +15V. The center levels of both the first drive voltage Vd1 and the fourth drive voltage Vd4 are +30V.

[0121] The difference between Specific Example 9 and Specific Example 10 is that Specific Example 10 requires a larger amount of heating. In Specific Example 9, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are ±5V, while in Specific Example 10, the first planar voltage difference (Vd1-Vd2) and the second planar voltage difference (Vd3-Vd4) are ±15V. As the voltage difference increases, the current flowing through the first transparent conductive film 11 and the second transparent conductive film 12 increases, and the amount of heat generated increases. Considering the voltage distribution in the planar direction x of the dimming device 10, the slope of the voltage in the planar direction x is greater in Specific Example 10.

[0122] At both time t1 in the first state and time t2 in the second state of the driving pattern, the voltage difference in the stacking direction at each position x in the planar direction of the dimming device 10 is the same absolute value (15V in specific example 9). At time t1 in the first state, the voltage of the first transparent conductive film 11 is higher than that of the second transparent conductive film 12 (+15V), and at time t2 in the second state, the voltage of the second transparent conductive film 12 is higher than that of the first transparent conductive film 11 (-15V). The liquid crystal layer 13 is semi-transparent.

[0123] Figure 19 shows the voltage patterns applied to the first terminal section 111, the second terminal section 112, the third terminal section 121, and the fourth terminal section 122, the voltage distribution in the planar direction x of the dimming device 10, the voltage-transmittance characteristics of the liquid crystal layer 13, and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 11 of the embodiment.

[0124] Specific Example 11 assumes an ambient temperature of 0°C and a gradient setting for the overall screen dimming. The gradient dimming shown in Figure 19 gradually decreases the transmittance from the left edge to the right edge of the screen, so that the left edge of the screen is the brightest and the right edge is the darkest. In Specific Example 11, the heating voltage is set to ±40V, and the dimming voltage within the screen is sloped.

[0125] The drive unit 20 generates the first drive voltage Vd1 and the third drive voltage Vd3 as square waves with the same amplitude (70V) but opposite phase. The drive unit 20 also generates the second drive voltage Vd2 and the fourth drive voltage Vd4 as square waves with the same amplitude (10V) but opposite phase.

[0126] In specific example 11, the high level (High(1)) of the first drive voltage Vd1 is set to +35V, and the low level (Low(1)) is set to -35V. The high level (High(2)) of the second drive voltage Vd2 is set to +5V, and the low level (Low(2)) is set to -5V. The high level (High(3)) of the third drive voltage Vd3 is set to +35V, and the low level (Low(3)) is set to -35V. The high level (High(4)) of the fourth drive voltage Vd4 is set to +5V, and the low level (Low(4)) is set to -5V. The center levels of the first drive voltage Vd1, the second drive voltage Vd2, the third drive voltage Vd3, and the fourth drive voltage Vd4 are all 0V.

[0127] The drive unit 20 generates the first drive voltage Vd1 and the fourth drive voltage Vd4 so that they are in phase and have the same center level, and the second drive voltage Vd2 and the third drive voltage Vd3 so that they are in phase and have the same center level. The drive unit 20 generates the pairs of the first drive voltage Vd1 and the fourth drive voltage Vd4 and the pairs of the second drive voltage Vd2 and the third drive voltage Vd3 so that they are out of phase.

[0128] With the above settings, in the planar direction x of the dimming device 10, the first voltage drop line connecting the first drive voltage Vd1 of the first terminal 111 and the second drive voltage Vd2 of the second terminal 112, and the second voltage drop line connecting the third drive voltage Vd3 of the third terminal 121 and the fourth drive voltage Vd4 of the fourth terminal 122, are not parallel but intersect at a certain position in the planar direction x. The designer can obtain the desired gradient dimming by adjusting the position where the first voltage drop line and the second voltage drop line intersect in the planar direction x of the dimming device 10. The transmittance of the liquid crystal layer 13 is lowest at the position where the first voltage drop line and the second voltage drop line intersect, and the transmittance of the liquid crystal layer 13 increases as the distance between the first voltage drop line and the second voltage drop line increases.

[0129] At time t1 in the first state of the drive pattern, the first planar voltage difference (Vd1-Vd2) is +40V and the second planar voltage difference (Vd3-Vd4) is -40V. At time t2 in the second state of the drive pattern, the first planar voltage difference (Vd1-Vd2) is -40V and the second planar voltage difference (Vd3-Vd4) is +40V. In both states, heat equivalent to the current flowing with a voltage difference of 40V is generated in both the first transparent conductive film 11 and the second transparent conductive film 12.

[0130] In the above explanation, we assumed an example in which two terminals, a first terminal portion 111 and a second terminal portion 112, are installed on the outer periphery of the first transparent conductive film 11, and two terminals, a third terminal portion 121 and a fourth terminal portion 122, are installed on the outer periphery of the second transparent conductive film 12.

[0131] The number of terminals installed on the outer periphery of the first transparent conductive film 11 is not limited to two, but may be three or more. Similarly, the number of terminals installed on the outer periphery of the second transparent conductive film 12 is not limited to two, but may be three or more.

[0132] In other words, the first transparent conductive film 11 may have a plurality of terminal portions on its outer periphery, and the second transparent conductive film 12 may have a plurality of terminal portions on its outer periphery at positions corresponding to the stacking direction of the plurality of terminal portions arranged on the outer periphery of the first transparent conductive film. In this case, the drive device 20 generates a plurality of drive voltages to be applied to the plurality of terminal portions of the first transparent conductive film 11 and a plurality of drive voltages to be applied to the plurality of terminal portions of the second transparent conductive film 12, such that a predetermined current flows between the plurality of terminal portions of the first transparent conductive film 11 and a predetermined current flows between the plurality of terminal portions of the second transparent conductive film 12, and the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is a predetermined distribution.

[0133] Hereinafter, we consider an example in which four terminals are installed at the upper left corner, lower left corner, upper right corner, and lower right corner of the first transparent conductive film 11, and four terminals are installed at the upper left corner, lower left corner, upper right corner, and lower right corner of the second transparent conductive film 12. Hereinafter, the terminal at the upper left corner of the first transparent conductive film 11 will be called the first terminal, the terminal at the lower right corner of the first transparent conductive film 11 will be called the second terminal, the terminal at the upper left corner of the second transparent conductive film 12 will be called the third terminal, the terminal at the lower right corner of the second transparent conductive film 12 will be called the fourth terminal, the terminal at the lower left corner of the first transparent conductive film 11 will be called the fifth terminal, the terminal at the upper right corner of the first transparent conductive film 11 will be called the sixth terminal, the terminal at the lower left corner of the second transparent conductive film 12 will be called the seventh terminal, and the terminal at the upper right corner of the second transparent conductive film 12 will be called the eighth terminal.

[0134] Figure 20 shows the drive voltage applied to the first terminal section to the eighth terminal section and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 12 of the embodiment.Specific example 12 assumes that the ambient temperature is 0°C and the dimming setting for the entire screen is set to gradient.The gradient dimming shown in Figure 20 gradually decreases the transmittance from the upper left corner to the lower right corner of the screen so that the upper left corner of the screen is the brightest and the lower right corner of the screen is the darkest.

[0135] In Figure 20, the first drive voltage applied to the first terminal is set to +20V, the second drive voltage applied to the second terminal is set to 0V, the fifth drive voltage applied to the fifth terminal is set to 0V, the sixth drive voltage applied to the sixth terminal is set to 0V, the third drive voltage applied to the third terminal is set to -20V, the fourth drive voltage applied to the fourth terminal is set to 0V, the seventh drive voltage applied to the seventh terminal is set to 0V, and the eighth drive voltage applied to the eighth terminal is set to 0V.

[0136] Current flows from the first terminal of the first transparent conductive film 11 toward the second, fifth, and sixth terminals. This current causes the first transparent conductive film 11 to generate heat. Similarly, current flows from the third terminal of the second transparent conductive film 12 toward the fourth, seventh, and eighth terminals. This current causes the second transparent conductive film 12 to generate heat.

[0137] The voltage difference in the stacking direction at the upper left corner of the dimming device 10 becomes 40V, and the voltage difference in the stacking direction at the lower right corner becomes 0V. Therefore, a gradient dimming effect is achieved in which the transmittance gradually decreases from the upper left corner to the lower right corner of the screen.

[0138] Figure 21 shows the drive voltage applied to the first terminal section to the eighth terminal section and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 13 of the embodiment.Specific example 13 assumes that the ambient temperature is 0°C and the dimming setting for the entire screen is set to gradient.The gradient dimming shown in Figure 21 gradually decreases the transmittance from the top edge to the bottom edge of the screen so that the top edge of the screen is the brightest and the bottom edge of the screen is the darkest.

[0139] In Figure 21, the first drive voltage applied to the first terminal is set to +20V, the second drive voltage applied to the second terminal is set to 0V, the fifth drive voltage applied to the fifth terminal is set to 0V, the sixth drive voltage applied to the sixth terminal is set to +20V, the third drive voltage applied to the third terminal is set to -20V, the fourth drive voltage applied to the fourth terminal is set to 0V, the seventh drive voltage applied to the seventh terminal is set to 0V, and the eighth drive voltage applied to the eighth terminal is set to -20V.

[0140] Current flows from the first and sixth terminals of the first transparent conductive film 11 toward the second and fifth terminals. This current causes the first transparent conductive film 11 to generate heat. Similarly, current flows from the third and eighth terminals of the second transparent conductive film 12 toward the fourth and seventh terminals. This current causes the second transparent conductive film 12 to generate heat.

[0141] The voltage difference in the stacking direction between the upper left corner and the upper right corner of the dimming device 10 becomes 40V, and the voltage difference in the stacking direction between the lower left corner and the lower right corner becomes 0V. Therefore, a gradient dimming is achieved in which the transmittance gradually decreases from the top edge to the bottom edge of the screen.

[0142] Figure 22 shows the drive voltage applied to the first terminal section to the eighth terminal section and the screen image of the transparent display on which the dimming device 10 is installed, according to specific example 14 of the embodiment.Specific example 14 assumes that the ambient temperature is 0°C and the dimming setting for the entire screen is set to gradient.The gradient dimming shown in Figure 22 gradually decreases the transmittance from the left edge and right edge of the screen towards the center, so that the left edge and right edge of the screen are the brightest and the center of the screen is the darkest.

[0143] In Figure 22, the first drive voltage applied to the first terminal is set to +20V, the second drive voltage applied to the second terminal is set to -20V, the fifth drive voltage applied to the fifth terminal is set to +20V, the sixth drive voltage applied to the sixth terminal is set to -20V, the third drive voltage applied to the third terminal is set to -20V, the fourth drive voltage applied to the fourth terminal is set to +20V, the seventh drive voltage applied to the seventh terminal is set to -20V, and the eighth drive voltage applied to the eighth terminal is set to +20V.

[0144] Current flows from the first and fifth terminals of the first transparent conductive film 11 toward the second and sixth terminals. This current causes the first transparent conductive film 11 to generate heat. Similarly, current flows from the fourth and eighth terminals of the second transparent conductive film 12 toward the third and seventh terminals. This current causes the second transparent conductive film 12 to generate heat.

[0145] The voltage difference in the stacking direction between the left and right edges of the dimming device 10 becomes 40V, and the voltage difference in the stacking direction at the center becomes 0V. Therefore, a gradient dimming is achieved in which the transmittance gradually decreases from the left and right edges of the screen towards the center.

[0146] As described above, according to this embodiment, by controlling the drive voltage applied to the multiple terminals installed on the first transparent conductive film 11 and the multiple terminals installed on the second transparent conductive film 12, it is possible to simultaneously heat the liquid crystal layer 13 to improve the response speed of the dimming device 10 in a low-temperature environment and perform dimming. In this respect, in a control method that separates the heating operation and the dimming operation, even if the heating effect is sufficient, the liquid crystal molecules may cool down after some time has passed since the dimming operation began, and the device may return to its original slow switching state.

[0147] In this embodiment, in order to generate heat in the first transparent conductive film 11, different drive voltages are set at multiple terminals installed on the first transparent conductive film 11 so that a voltage difference is generated within the plane of the first transparent conductive film 11. Similarly, in order to generate heat in the second transparent conductive film 12, different drive voltages are set at multiple terminals installed on the second transparent conductive film 12 so that a voltage difference is generated within the plane of the second transparent conductive film 12. At this time, the voltage gradient within the plane of the first transparent conductive film 11 and the voltage gradient within the plane of the second transparent conductive film 12 are controlled to be the same in all regions, so that the voltage difference in the stacking direction between the first transparent conductive film 11 and the second transparent conductive film 12 is the same.

[0148] By controlling the voltage difference between the first transparent conductive film 11 and the second transparent conductive film 12, the transmittance of the liquid crystal layer 13 can be controlled, enabling dimming. In this embodiment, the voltage gradient within the plane of the first transparent conductive film 11 and the voltage gradient within the plane of the second transparent conductive film 12 are controlled to be the same, thereby suppressing dimming unevenness. Therefore, display unevenness (specifically, brightness unevenness, color unevenness) or flickering of the display to which the dimming device 10 is attached can be suppressed.

[0149] Furthermore, the heating effect can be enhanced by heating the liquid crystal layer 13 from both sides of the first transparent conductive film 11 and the second transparent conductive film 12. Since the amount of heating is controlled by the voltage gradient in the plane of the first transparent conductive film 11 and the voltage gradient in the plane of the second transparent conductive film 12, the amount of heating can be controlled without depending on the voltage difference in the stacking direction used to control transmittance. Therefore, it is possible to prevent overheating or underheating depending on the dimming control. Thus, it is possible to avoid control at unnecessarily high drive voltages due to overheating, and unnecessary power consumption can be suppressed.

[0150] Furthermore, by periodically switching the heating current direction of the first transparent conductive film 11 and the heating current direction of the second transparent conductive film 12, uneven heating of the liquid crystal layer 13 can be suppressed, and the deterioration of the first transparent conductive film 11 and the second transparent conductive film 12 can be suppressed.

[0151] Thus, according to this embodiment, the quality of dimming and heating of the dimming device 10 can be improved.

[0152] The present disclosure has been described above based on embodiments. The embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure.

[0153] In the embodiment described above, an example was explained in which the dimming device 10 is attached to the front of a transparent display of an infotainment device in a vehicle. However, the use of the dimming device 10 is not limited to being attached to the front of a display. For example, by attaching the dimming device 10 to the window of a vehicle or building, the amount of light entering the vehicle or building can be controlled. By lowering the transmittance, it can be used as a light-blocking curtain, which also contributes to privacy protection.

[0154] The embodiments can be described as follows:

[0155] A dimming device (1) according to one aspect of this disclosure is Dimming device (10), The system includes a drive unit (20) that drives the dimming device (10), The dimming device (10) is Liquid crystal layer (13), A first transparent conductive film (11) is disposed on one side of the liquid crystal layer (13) in the stacking direction, The liquid crystal layer (13) comprises a second transparent conductive film (12) disposed on the opposite side of the stacking direction, The first transparent conductive film (11) includes a first terminal group which includes a plurality of terminals located on the outer periphery, The second transparent conductive film (12) includes a second terminal group, which comprises a plurality of terminals located on the outer periphery, at positions corresponding to the lamination direction of each of the plurality of terminals included in the first terminal group. The aforementioned drive device (20) Multiple drive voltages are generated to be applied to multiple terminals in the first terminal group and multiple drive voltages are generated to be applied to multiple terminals in the second terminal group such that a predetermined current flows between multiple terminals in the first terminal group, a predetermined current flows between multiple terminals in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film (11) and the second transparent conductive film (12) is a predetermined distribution. According to this, it is possible to simultaneously achieve dimming and heating of the dimming device (10) while improving the quality of dimming and heating. In a dimming device (1) according to one aspect of this disclosure, for example, The first group of terminals is, A first terminal (111) is arranged in a first region on the outer periphery of the first transparent conductive film (11), The first transparent conductive film (11) comprises a second terminal (112) located in a second region on the outer periphery facing the first terminal (111), The second group of terminals is, A third terminal (121) is located in the outer periphery of the second transparent conductive film, in a third region corresponding to the first region and the lamination direction, The second transparent conductive film (12) comprises a fourth terminal (122) located in a fourth region on the outer periphery facing the third terminal (121), The aforementioned drive device (20) A first drive voltage applied to the first terminal (111), a second drive voltage applied to the second terminal (112), a third drive voltage applied to the third terminal (121), and a fourth drive voltage applied to the fourth terminal (122) may be generated such that a predetermined current flows between the first terminal (111) and the second terminal (112), a predetermined current flows between the third terminal (121) and the fourth terminal (122), and the distribution of the voltage difference between the first transparent conductive film (11) and the second transparent conductive film (12) is a predetermined distribution. According to this, by controlling the drive voltage of the four channels, it is possible to simultaneously achieve dimming and heating of the dimming device (10) while improving the quality of dimming and heating. In a dimming device (1) according to one aspect of this disclosure, for example, The aforementioned drive device (20) The first drive voltage, second drive voltage, third drive voltage, and fourth drive voltage may be generated such that a predetermined current flows between the first terminal (111) and the second terminal (112), a predetermined current flows between the third terminal (121) and the fourth terminal (122), and the distribution of the voltage difference between the first transparent conductive film (11) and the second transparent conductive film (12) is uniform. According to this, the entire surface of the dimming device (10) can be dimmed uniformly. In a dimming device (1) according to one aspect of this disclosure, for example, The aforementioned drive device (20) The voltage difference between the first drive voltage and the second drive voltage, and the voltage difference between the third drive voltage and the fourth drive voltage, may be controlled to increase as the required amount of heating increases. According to this, the amount of heating required to heat the liquid crystal layer (13) can be controlled to an appropriate amount without relying on dimming control. In a dimming device (1) according to one aspect of this disclosure, for example, The aforementioned drive device (20) The voltage difference between the first drive voltage and the third drive voltage, and the voltage difference between the second drive voltage and the fourth drive voltage may be controlled according to the required transmittance of the liquid crystal layer (13). According to this, the transmittance of the liquid crystal layer (13) can be controlled to an appropriate value without relying on heating control. In a dimming device (1) according to one aspect of this disclosure, for example, The aforementioned drive device (20) The first drive voltage and the second drive voltage are in phase and have the same center level. The third drive voltage and the fourth drive voltage are in phase and have the same center level. The first drive voltage and the second drive voltage pair and the third drive voltage and the fourth drive voltage pair are in opposite phases. The first drive voltage, the second drive voltage, the third drive voltage, and the fourth drive voltage may be generated as square wave voltages. According to this, the amount of heat generated by the first transparent conductive film (11) and the amount of heat generated by the second transparent conductive film (12) can be made equal, and the direction in which the heating current flows can be periodically switched, thereby suppressing uneven heating and preventing deterioration of each material. In a dimming device (1) according to one aspect of this disclosure, for example, The aforementioned drive device (20) When the dimming device (10) performs gradient dimming, the voltage difference between the first drive voltage and the third drive voltage and the voltage difference between the second drive voltage and the fourth drive voltage may be set to different values ​​so that the distribution of the voltage difference between the first transparent conductive film (11) and the second transparent conductive film (12) is gradient. According to this, the dimming device (10) can be dimmed in a gradient. A drive unit (20) of a dimming device (1) according to one aspect of this disclosure is A drive unit (20) for a dimming device (10) that drives a dimming device (10), The dimming device (10) is Liquid crystal layer (13), A first transparent conductive film (11) is disposed on one side of the liquid crystal layer (13) in the stacking direction, The liquid crystal layer (13) comprises a second transparent conductive film (12) disposed on the opposite side of the stacking direction, The first transparent conductive film (11) includes a first terminal group which includes a plurality of terminals located on the outer periphery, The second transparent conductive film (12) includes a second terminal group, which comprises a plurality of terminals located on the outer periphery, at positions corresponding to the lamination direction of each of the plurality of terminals included in the first terminal group. The aforementioned drive device (20) Multiple drive voltages are generated to be applied to multiple terminals in the first terminal group and multiple drive voltages are generated to be applied to multiple terminals in the second terminal group such that a predetermined current flows between multiple terminals in the first terminal group, a predetermined current flows between multiple terminals in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film (11) and the second transparent conductive film (12) is a predetermined distribution. According to this, it is possible to simultaneously achieve dimming and heating of the dimming device (10) while improving the quality of dimming and heating. A method for driving a dimming device (1) according to one aspect of this disclosure is: A method for driving a dimming device (10), The dimming device (10) is Liquid crystal layer (13), A first transparent conductive film (11) is disposed on one side of the liquid crystal layer (13) in the stacking direction, The liquid crystal layer (13) comprises a second transparent conductive film (12) disposed on the opposite side of the stacking direction, The first transparent conductive film (11) includes a first terminal group which includes a plurality of terminals located on the outer periphery, The second transparent conductive film (12) includes a second terminal group, which comprises a plurality of terminals located on the outer periphery, at positions corresponding to the lamination direction of each of the plurality of terminals included in the first terminal group. The aforementioned drive device (20) Multiple drive voltages are generated to be applied to multiple terminals in the first terminal group and multiple drive voltages are generated to be applied to multiple terminals in the second terminal group such that a predetermined current flows between multiple terminals in the first terminal group, a predetermined current flows between multiple terminals in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film (11) and the second transparent conductive film (12) is a predetermined distribution. According to this, it is possible to simultaneously achieve dimming and heating of the dimming device (10) while improving the quality of dimming and heating. [Explanation of symbols]

[0156] 1 Dimming device, 10 Dimming device, 11 First transparent conductive film, 111 First terminal section, 112 Second terminal section, 12 Second transparent conductive film, 121 Third terminal section, 122 Fourth terminal section, 13 Liquid crystal layer, 20 Driving device, 21 Input section, 22 Power supply section, 23 Control coefficient setting section, 24 Timing control circuit, 25 Timer circuit, 26 Voltage generation circuit, 27 Driving circuit, 28 Output voltage switching conversion section, 281 First switching section, 282 Second switching section, 283 First level conversion section, 284 Second level conversion section, Qa First switching element, Qb Second switching element.

Claims

1. Dimming devices and The system includes a drive device for driving the dimming device, The dimming device is The liquid crystal layer, A first transparent conductive film is disposed on one side of the liquid crystal layer in the stacking direction, The liquid crystal layer comprises a second transparent conductive film disposed on the opposite side of the layering direction, The first transparent conductive film comprises a first terminal group including a plurality of terminals located on the outer periphery, The second transparent conductive film includes a second terminal group, which comprises a plurality of terminals located on the outer periphery, at positions corresponding to the lamination direction of each of the plurality of terminals included in the first terminal group. The drive device is Multiple drive voltages are generated to be applied to multiple terminals in the first terminal group and multiple drive voltages are generated to be applied to multiple terminals in the second terminal group such that a predetermined current flows between multiple terminals in the first terminal group, a predetermined current flows between multiple terminals in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is a predetermined distribution. Dimming device.

2. The first group of terminals is, A first terminal is arranged in a first region on the outer periphery of the first transparent conductive film, The first transparent conductive film comprises a second terminal located in a second region on the outer periphery facing the first terminal, The second group of terminals is, A third terminal is located in a third region on the outer periphery of the second transparent conductive film, which corresponds to the first region and the lamination direction. The second transparent conductive film comprises a fourth terminal located in a fourth region on the outer periphery facing the third terminal, The drive device is A first drive voltage applied to the first terminal, a second drive voltage applied to the second terminal, a third drive voltage applied to the third terminal, and a fourth drive voltage applied to the fourth terminal are generated such that a predetermined current flows between the first terminal and the second terminal, a predetermined current flows between the third terminal and the fourth terminal, and the voltage difference distribution between the first transparent conductive film and the second transparent conductive film is a predetermined distribution. The dimming device according to claim 1.

3. The drive device is The first drive voltage, second drive voltage, third drive voltage, and fourth drive voltage are generated such that a predetermined current flows between the first terminal and the second terminal, a predetermined current flows between the third terminal and the fourth terminal, and the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is uniform. The dimming device according to claim 2.

4. The drive device is The voltage difference between the first drive voltage and the second drive voltage, and the voltage difference between the third drive voltage and the fourth drive voltage are controlled to increase as the required amount of heating increases. The dimming device according to claim 2.

5. The drive device is The voltage difference between the first drive voltage and the third drive voltage, and the voltage difference between the second drive voltage and the fourth drive voltage are controlled according to the required transmittance of the liquid crystal layer. The dimming device according to claim 2.

6. The drive device is The first drive voltage and the second drive voltage are in phase and have the same center level. The third drive voltage and the fourth drive voltage are in phase and have the same center level. The first drive voltage and the second drive voltage pair and the third drive voltage and the fourth drive voltage pair are in opposite phases. The first drive voltage, the second drive voltage, the third drive voltage, and the fourth drive voltage are generated as square wave voltages. The dimming device according to claim 2.

7. The drive device is When the dimming device performs gradient dimming, the voltage difference between the first drive voltage and the third drive voltage and the voltage difference between the second drive voltage and the fourth drive voltage are set to different values ​​so that the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is gradient. The dimming device according to claim 2.

8. A driver for a dimming device that drives a dimming device, The dimming device is The liquid crystal layer, A first transparent conductive film is disposed on one side of the liquid crystal layer in the stacking direction, The liquid crystal layer comprises a second transparent conductive film disposed on the opposite side of the layering direction, The first transparent conductive film comprises a first terminal group including a plurality of terminals located on the outer periphery, The second transparent conductive film includes a second terminal group, which comprises a plurality of terminals located on the outer periphery, at positions corresponding to the lamination direction of each of the plurality of terminals included in the first terminal group. The drive device is Multiple drive voltages are generated to be applied to multiple terminals in the first terminal group and multiple drive voltages are generated to be applied to multiple terminals in the second terminal group such that a predetermined current flows between multiple terminals in the first terminal group, a predetermined current flows between multiple terminals in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is a predetermined distribution. A driver for a dimming device.

9. A method for driving a dimming device, The dimming device is The liquid crystal layer, A first transparent conductive film is disposed on one side of the liquid crystal layer in the stacking direction, The liquid crystal layer comprises a second transparent conductive film disposed on the opposite side of the layering direction, The first transparent conductive film comprises a first terminal group including a plurality of terminals located on the outer periphery, The second transparent conductive film includes a second terminal group, which comprises a plurality of terminals located on the outer periphery, at positions corresponding to the lamination direction of each of the plurality of terminals included in the first terminal group. The drive device is Multiple drive voltages are generated to be applied to multiple terminals in the first terminal group and multiple drive voltages are generated to be applied to multiple terminals in the second terminal group such that a predetermined current flows between multiple terminals in the first terminal group, a predetermined current flows between multiple terminals in the second terminal group, and the distribution of the voltage difference between the first transparent conductive film and the second transparent conductive film is a predetermined distribution. A method for driving a dimming device.

Images