JP7110760B2 - dimmer - Google Patents

Description

The present invention relates to a dimmer device driven by an alternating voltage.

The light control portion of the light control sheet included in the light control device has a light control layer and a pair of transparent electrode layers sandwiching the light control layer. The light transmittance of the light control portion is changed by changing the orientation state of the liquid crystal molecules included in the light control layer according to the potential difference between the pair of transparent electrode layers. As a driving voltage for generating the potential difference, an AC voltage having a waveform such as a sine wave or a rectangular wave is used (see, for example, Patent Document 1).

JP 2014-48353 A

When the application of the driving voltage to the light control section is stopped, the potential difference between the transparent electrode layers converges toward an intermediate potential (0 V) between the high potential and the low potential, and as a result, the light control section becomes transparent. It changes from a first state to a second state that is opaque, or from a first state that is opaque to a second state that is transparent. Here, if the application of the drive voltage is stopped when the magnitude of the drive voltage is near 0 V, the potential difference between the transparent electrode layers is close to 0 V when the application of the drive voltage is stopped. The time required to change to the second state is short. However, if the application of the driving voltage is stopped while the magnitude of the driving voltage is away from 0 V, the potential difference between the transparent electrode layers is large at the time when the application of the driving voltage is stopped, so that the state changes from the first state to the second state. It takes a long time to change to In particular, when the drive voltage is a rectangular wave, the period during which the magnitude of the voltage is maximized is long within the cycle. It is likely that it takes time to change to the second state.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light control device capable of enhancing the responsiveness of the light transmittance of the light control unit when driving is stopped.

A light control device that solves the above problems is a light control unit that includes a light control layer containing a liquid crystal composition and a pair of transparent electrode layers sandwiching the light control layer, and a drive voltage that is an AC voltage is applied. and a discharging section that discharges the charge remaining in the transparent electrode layer in accordance with the stop of the application of the driving voltage to the light adjusting section.

According to the above configuration, when the application of the driving voltage is stopped, the electric charge remaining in the transparent electrode layer is discharged by the discharge section. becomes equipotential. Therefore, it is possible to improve the responsiveness of the light transmittance of the light control unit when the drive is stopped.

The light control device may include a voltage generation circuit that receives supply of a DC voltage and generates the square-wave drive voltage.
Compared to drive voltages with other waveforms, square-wave drive voltages change sharply from high potential to low potential or from low potential to high potential, so application of the drive voltage can be stopped at an arbitrary timing. In this case, charges tend to remain in the transparent electrode layer. Therefore, if a light control device using a square-wave drive voltage is provided with a discharge unit, it is highly beneficial to improve the responsiveness of the light transmittance of the light control unit when driving is stopped. In addition, since the drive voltage is generated from the DC voltage, the light control device can be driven by using a battery such as an on-vehicle battery in places such as vehicles where it is difficult to obtain power from a commercial AC power supply.

In the above light control device, the discharge section may include a resistor connected in parallel with the light control section in a path for applying the drive voltage to the light control section.
According to the above configuration, the discharge section that discharges the charges remaining in the transparent electrode layer is preferably realized.

In the above light control device, the discharge section is a resistance element connected in parallel with the light control section in a path for applying the drive voltage to the light control section, and the drive voltage to the light control section is The resistive element may be configured to form a closed circuit in which the dimming section and the resistive element are connected in series when the application is stopped.
According to the above configuration, the discharge section that discharges the charge remaining in the transparent electrode layer is preferably realized.

In the above light control device, the discharge unit further includes an auxiliary switch and a control unit that controls on/off of the auxiliary switch, and the resistance element and the A series circuit with an auxiliary switch is connected in parallel with the light control unit, and the control unit turns off the auxiliary switch while the driving voltage is being applied to the light control unit, thereby controlling the light control unit. The auxiliary switch may be turned on when the application of the drive voltage is stopped.

According to the above configuration, when the application of the driving voltage is stopped, a closed circuit is formed by the light control unit and the resistance element, and the charge remaining in the transparent electrode layer is discharged, while the light control device is being driven. There is no power consumption of the resistive element in . Therefore, it is possible to employ a resistance element with a smaller resistance value than in a form in which the drive voltage applied to the dimming unit is always applied to the resistance element. Employing a resistive element with a smaller resistance value makes it possible to speed up the discharge of charges from the transparent electrode layer, that is, to further improve the responsiveness of the light transmittance of the light control section when driving is stopped. is possible.

In the light control device described above, the voltage generation circuit may include a first switch, a second switch, a third switch, and a fourth switch. The first switch and the second switch are connected in series such that the first switch is connected to the positive side of a power supply and the second switch is connected to the negative side of the power supply. The third switch and the fourth switch are connected in series such that the third switch is connected to the positive side of the power supply and the fourth switch is connected to the negative side of the power supply. A set of the first switch and the second switch and a set of the third switch and the fourth switch are connected in parallel to a power supply. One of the pair of transparent electrode layers is connected to the connection point between the first switch and the second switch, and the pair of transparent electrode layers is connected to the connection point between the third switch and the fourth switch. are connected to the other of the transparent electrode layers. The light control device includes a control unit that controls turning on and off of each switch, and the control unit turns on the first switch and the fourth switch and turns off the second switch and the third switch. and the control of turning on the second switch and the third switch and turning off the first switch and the fourth switch may be alternately repeated to generate the drive voltage .
According to the above configuration, a square-wave drive voltage is preferably generated from the DC voltage.

In the light control device, the discharge unit includes the control unit, and the control unit turns on the first switch and the third switch and turns off the second switch and the fourth switch, Alternatively, the charge remaining in the transparent electrode layer may be discharged by performing control to turn on the second switch and the fourth switch and turn off the first switch and the third switch.

According to the above configuration, the discharge section that discharges the charges remaining in the transparent electrode layer is preferably realized. In addition, since the voltage generation circuit for generating the driving voltage is used for discharging, the circuit configuration is simpler than the configuration in which a resistor connected in parallel with the light control unit is provided.

The above-described light control device includes a light control sheet having the light control portion and a resistance portion functioning as the resistor, wherein the resistance portion constitutes one of the pair of transparent electrode layers and a single conductive film. It may have a resistive layer that

According to the above configuration, since the light control sheet has a portion that functions as a resistor as a part of the sheet, it is compared with a form in which the resistor is incorporated as an element in a circuit for driving the light control unit. This simplifies the configuration of the circuit.

According to the present invention, it is possible to improve the responsiveness of the light transmittance of the light control section when driving is stopped.

The figure which shows the cross-section of the light control sheet about 1st Embodiment of a light control apparatus. The figure which shows the equivalent circuit of the light control part which the light control sheet of 1st Embodiment contains. The figure which shows the electrical structure of the light modulation apparatus of 1st Embodiment. 4A to 4C are timing charts showing changes in switch control and voltage between transparent electrode layers in the light control device according to the first embodiment; FIG. 4 is a diagram showing changes in voltage between transparent electrode layers when application of a driving voltage is stopped; The figure which shows the electrical structure of a light control apparatus about 2nd Embodiment of a light control apparatus. The timing chart which shows control of the switch in the light modulation apparatus of 2nd Embodiment. The figure which shows the electrical structure of a light control apparatus about 3rd Embodiment of a light control apparatus. The timing chart which shows control of the switch in the light modulation apparatus of 3rd Embodiment. The figure which shows the structure of a light control apparatus about 4th Embodiment of a light control apparatus.

(First embodiment)
A first embodiment of a light control device will be described with reference to FIGS. 1 to 5. FIG. The light control device includes a light control sheet including a light control section, a drive circuit including a circuit for generating a drive voltage applied to the light control section, and a control section for controlling the operation of the drive circuit.

[Configuration of light control sheet]
The structure of the light control sheet will be described with reference to FIG. As shown in FIG. 1, the light control sheet 10 includes a light control layer 11, a first transparent electrode layer 12A and a second transparent electrode layer 12B, which are a pair of transparent electrode layers, and a first transparent electrode layer 12B, which is a pair of transparent support layers. It has a transparent support layer 13A and a second transparent support layer 13B. The first transparent electrode layer 12A and the second transparent electrode layer 12B sandwich the light control layer 11, and the first transparent support layer 13A and the second transparent support layer 13B sandwich the light control layer 11 and the transparent electrode layers 12A and 12B. sandwiched between The first transparent support layer 13A supports the first transparent electrode layer 12A, and the second transparent support layer 13B supports the second transparent electrode layer 12B.

The first transparent electrode layer 12A and the second transparent electrode layer 12B are connected to the drive circuit 20 through wires extending from terminal portions provided on the surfaces of the respective transparent electrode layers 12A and 12B. The first transparent electrode layer 12A and the second transparent electrode layer 12B are electrodes that face each other and receive the application of a driving voltage. The area to be adjusted is the light control section 15 .

The light control layer 11 contains a liquid crystal composition. The light control layer 11 is made of, for example, a polymer network liquid crystal (PNLC), a polymer dispersed liquid crystal (PDLC), a capsule nematic liquid crystal (NCAP: Nematic Curvilinear Aligned Phase), or the like. Configured. For example, a polymer network type liquid crystal has a polymer network having a three-dimensional mesh shape, and holds liquid crystal molecules in the voids of the polymer network. The liquid crystal molecules included in the light control layer 11 have, for example, positive dielectric anisotropy, and the dielectric constant in the long axis direction of the liquid crystal molecules is larger than the dielectric constant in the short axis direction of the liquid crystal molecules. Liquid crystal molecules are, for example, Schiff base, azo, azoxy, biphenyl, terphenyl, benzoate, tolan, pyrimidine, cyclohexanecarboxylate, phenylcyclohexane, and dioxane liquid crystal molecules. be.

Each of the first transparent electrode layer 12A and the second transparent electrode layer 12B is a conductive transparent layer. Materials constituting the transparent electrode layers 12A and 12B include, for example, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, carbon nanotubes (CNT), poly(3,4-ethylenediethylene). oxythiophene) (PEDOT), and the like.

Each of the first transparent support layer 13A and the second transparent support layer 13B is a transparent substrate. As the transparent support layers 13A and 13B, for example, a glass substrate, a silicon substrate, or a high-performance substrate made of polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, triacetyl cellulose, or the like is used. A molecular film is used.

When a potential difference is generated between the first transparent electrode layer 12A and the second transparent electrode layer 12B, the liquid crystal molecules contained in the light control layer 11 are aligned, and the long axis direction of the liquid crystal molecules is between the transparent electrode layers 12A and 12B. along the electric field direction of As a result, light can easily pass through the light modulating layer 11 . When a drive voltage, which is an AC voltage whose direction changes with a sufficiently small period, is applied to the light control section 15, the light control section 15 appears transparent. That is, the dimming unit 15 is in the first state.

On the other hand, when the first transparent electrode layer 12A and the second transparent electrode layer 12B are at the same potential, the long axis directions of the liquid crystal molecules included in the light control layer 11 are irregular. Therefore, the light incident on the light modulating layer 11 is scattered. When the state in which the first transparent electrode layer 12A and the second transparent electrode layer 12B are at the same potential continues, the light control section 15 appears cloudy and opaque. That is, the dimming unit 15 is in the second state.

The electrical configuration of the light control sheet 10 will be described with reference to FIG. FIG. 2 is a diagram showing an equivalent circuit of the dimming unit 15. As shown in FIG. An equivalent circuit of the dimming unit 15 includes a capacitor Co, a primary resistor Rh, and a secondary resistor Rl. The main resistor Rh is connected in parallel with the capacitor Co with respect to the secondary resistor Rl, and the secondary resistor Rl is connected in series with the capacitor Co. The capacitor Co corresponds to the capacitance component of the light control layer 11 of the light control section 15 , and the main resistance Rh corresponds to the internal resistance component of the light control layer 11 of the light control section 15 . The secondary resistance Rl corresponds to the contact resistance between the transparent electrode layers 12A and 12B and the terminals. The resistance value of the sub-resistor Rl is sufficiently smaller than the resistance value of the main resistor Rh, and the dimming unit 15 equivalently resembles an RC parallel circuit.

[Configuration of light control device]
The configuration of the light control device will be described with reference to FIG. As shown in FIG. 3 , the light control device 100 includes a light control sheet 10 , a drive circuit 20 connected to the light control sheet 10 , and a control section 30 connected to the drive circuit 20 .

The drive circuit 20 includes an additional resistor R1 connected in parallel to the light control section 15 of the light control sheet 10, and a voltage generation circuit 25 connected to the additional resistor R1 and a DC power supply DC. The additional resistance R1 is an example of a resistor and constitutes the load section 21 . The DC power supply DC supplies a constant DC voltage. Further, the drive circuit 20 includes a main switch SWm between the DC power supply DC and the voltage generation circuit 25, and the DC power supply DC and the voltage generation circuit 25 are connected via the main switch SWm.

The voltage generation circuit 25 includes four switching elements: a first switch SW1, a second switch SW2, a third switch SW3, and a fourth switch SW4. The first switch SW1 and the second switch SW2 are connected in series such that the first switch SW1 is connected to the positive side of the direct current power supply DC and the second switch SW2 is connected to the negative side of the direct current power supply DC. there is The third switch SW3 and the fourth switch SW4 are connected in series such that the third switch SW3 is connected to the positive side of the direct current power supply DC and the fourth switch SW4 is connected to the negative side of the direct current power supply DC. there is A set of switches consisting of the first switch SW1 and the second switch SW2 and a set of switches consisting of the third switch SW3 and the fourth switch SW4 are connected in parallel to the DC power supply DC.

One terminal of the additional resistor R1 is connected to the first connection point P1 located between the first switch SW1 and the second switch SW2. The other terminal of the additional resistor R1 is connected to the second connection point P2 located between the third switch SW3 and the fourth switch SW4. A first transparent electrode layer 12A of the light control section 15 is connected to the first connection point P1, and a second transparent electrode layer 12B of the light control section 15 is connected to the second connection point P2. Thus, a full bridge circuit is formed by connecting the voltage generation circuit 25, the additional resistor R1, and the dimming unit 15. FIG.

Semiconductor switches such as power MOSFETs and power transistors are used as the switches SWm, SW1 to SW4. A relay such as a photoMOS relay may be used instead of the semiconductor switch.

The control unit 30 is connected to each of the switches SWm, SW1 to SW4, and controls turning on/off of these switches SWm, SW1 to SW4. The control unit 30 includes, for example, a microcomputer (microcontroller) and a driver circuit for driving the switching elements. An FPGA (Field Programmable Gate Array) or the like may be used instead of the microcomputer.

[Operation of dimmer]
The operation of the light control device 100 will be described with reference to FIGS. 4 and 5. FIG. During the application period of the drive voltage, the controller 30 turns on and off the first switch SW1 and the fourth switch SW4 at the same time. Similarly, during the application period of the drive voltage, the controller 30 turns on and off the second switch SW2 and the third switch SW3 at the same time. 4A is a timing chart showing ON/OFF switching of the first switch SW1 and the fourth switch SW4, and FIG. 4B is a timing chart showing ON/OFF switching of the second switch SW2 and the third switch SW3. It is a timing chart showing switching. FIG. 4C is a timing chart showing the magnitude of the voltage V between the first transparent electrode layer 12A and the second transparent electrode layer 12B of the light control sheet 10. As shown in FIG. Note that the periods shown in FIGS. 4A to 4C are drive voltage application periods, and the main switch SWm is turned on.

As shown in FIGS. 4A and 4B, the first switch SW1 and the fourth switch SW4 are turned on simultaneously at timing t1 and turned off simultaneously at timing t2. Both the second switch SW2 and the third switch SW3 are off while the first switch SW1 and the fourth switch SW4 are on. The second switch SW2 and the third switch SW3 are turned on simultaneously at timing t3 and turned off simultaneously at timing t4. While the second switch SW2 and the third switch SW3 are on, both the first switch SW1 and the fourth switch SW4 are off.

The period during which the first switch SW1 and the fourth switch SW4 are on, that is, the period from timing t1 to timing t2 is the first application period Tn1, and the period during which the second switch SW2 and the third switch SW3 are on, that is, , the period from timing t3 to timing t4 is the second application period Tn2. The length of the first application period Tn1 and the length of the second application period Tn2 are the same, and the first application period Tn1 and the second application period Tn2 are alternately repeated. In other words, the control unit 30 alternately turns on the set of the first switch SW1 and the fourth switch SW4 and the set of the second switch SW2 and the third switch SW3.

During the first application period Tn1, the first transparent electrode layer 12A of the dimming section 15 is connected to the positive electrode side of the direct current power source DC, and the second transparent electrode layer 12B is connected to the negative electrode side of the direct current power source DC. On the other hand, during the second application period Tn2, the second transparent electrode layer 12B is connected to the positive electrode side of the DC power supply DC, and the first transparent electrode layer 12A is connected to the negative electrode side of the DC power supply DC.

Therefore, as shown in FIG. 4C, the direction of the voltage applied to the light control section 15 is reversed between the first application period Tn1 and the second application period Tn2. By alternately repeating the first application period Tn<b>1 and the second application period Tn<b>2 at a predetermined cycle, a square-wave AC voltage is applied to the dimming unit 15 .

As described above, in the present embodiment, the voltage generation circuit 25 is controlled by the control unit 30 to generate a rectangular wave drive voltage from the DC voltage supplied by the DC power supply DC. It is applied to the light section 15 .

Here, FIG. 5 is a diagram showing transition of the voltage V between the first transparent electrode layer 12A and the second transparent electrode layer 12B when the application of the drive voltage to the light control section 15 is stopped. For example, when the user of the light control device 100 wants to make the light control unit 15 opaque, the control unit 30 detects this operation and turns off the main switch SWm as the user operates the external switch of the light control device 100. to As a result, the direct-current power supply DC and the voltage generation circuit 25 are disconnected, and the application of the driving voltage is stopped.

As shown in FIG. 5, for example, at timing t5 within the first application period Tn1, it is assumed that the main switch SWm is turned off and the application of the driving voltage to the light control section 15 is stopped. At this time, the voltage V gradually decreases from the voltage Va applied during the first application period Tn1. Specifically, as described above, since the dimming unit 15 can be equivalently regarded as an RC parallel circuit, the voltage V decreases with the passage of time t according to the following formula (1).

V=Va×e ^(−t/CR) (1)
Therefore, the smaller the time constant τ=CR, the shorter the time required for the voltage V to become 0, that is, the time required for the first transparent electrode layer 12A and the second transparent electrode layer 12B to become equipotential. .

The magnitude of the capacitance component C that defines the time constant τ is determined by the magnitude of the capacitance of the capacitor Co in the equivalent circuit shown in FIG. On the other hand, since the additional resistance R1 is connected in parallel with the light control unit 15, the resistance component R that defines the time constant τ is the sum of the main resistance Rh and the additional resistance R1. That is, the resistance component R becomes smaller than when the additional resistor R1 is not provided, and as a result the time constant τ becomes smaller. Therefore, the time required for the first transparent electrode layer 12A and the second transparent electrode layer 12B to have the same electric potential after the electric charge is discharged is shortened. As a result, it is possible to shorten the time required for the light control section 15 to change from the first state to the second state when the application of the drive voltage is stopped.

In order to reduce the time constant τ=CR, it is preferable that the resistance value of the additional resistor R1 is as small as possible. On the other hand, since current also flows through the additional resistor R1 during application of the drive voltage, the smaller the resistance value of the additional resistor R1, the larger the power consumption of the additional resistor R1 and the larger the amount of heat generated by the additional resistor R1. Therefore, it is preferable that the resistance value of the additional resistor R1 is set in a range smaller than the resistance value of the main resistor Rh, taking into consideration both the rate of decrease in the voltage V and the power consumption of the additional resistor R1.

For example, when the dimming unit 15 has a size of 1 m×1 m in a plan view and a capacitance of 6.7 μF, and the resistance value of the additional resistor R1 is 10 kΩ, 0 after the application of the driving voltage is stopped. At 0.2 seconds, voltage V drops to 1.8% of voltage Va. With such a configuration, it is possible to change the light control unit 15 from the first state to the second state in a short period of time that is unrecognizable to humans.

Note that the light control device 100 may include a heat dissipation member for dissipating heat generated by the heat generated by the additional resistor R1. If the light control device 100 is configured to include a heat dissipation member, it is possible to prevent the portion where the additional resistor R1 is provided from becoming excessively hot.

In the first embodiment described above, application of the drive voltage is stopped by turning off the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4 in the voltage generation circuit 25 instead of turning off the main switch SWm. may be realized by turning off all of the In this case, the drive circuit 20 may not be provided with the main switch SWm.

In the first embodiment, the load section 21 and the control section 30 function as a discharge section that discharges the charges remaining in the transparent electrode layers 12A and 12B when application of the drive voltage is stopped. The control unit 30 as a discharge unit controls the main switch SWm or controls the first to fourth switches SW1 to SW4 to switch the light control unit 15, the additional resistor R1, and the DC power supply together with the stop of the application of the drive voltage. A closed circuit is formed in which the dimming unit 15 and the additional resistor R1 are connected in series by interrupting the conduction with DC.

As described above, according to the first embodiment, the following effects can be obtained.
(1) When the application of the drive voltage is stopped, the electric charges remaining in the transparent electrode layers 12A and 12B are discharged by the discharge section. Therefore, the time required for the first transparent electrode layer 12A and the second transparent electrode layer 12B to reach the same potential becomes shorter than in a configuration in which no discharge section is provided. As a result, it is possible to shorten the time required for the light control unit 15 to change from the first state to the second state when the application of the driving voltage is stopped. The responsiveness of the light transmittance of the portion 15 can be enhanced.

(2) The discharge unit is connected in parallel with the light control unit 15 in the path for applying the drive voltage to the light control unit 15, and forms a closed circuit with the light control unit 15 when the application of the drive voltage is stopped. It includes an additional resistor R1 which is a configured resistive element. According to such a configuration, a discharge section that discharges charges remaining in the transparent electrode layers 12A and 12B is preferably realized. Further, the light control unit 15 and the additional resistor R1 are electrically connected both during the application of the drive voltage and when the application of the drive voltage is stopped. Therefore, for example, compared to a configuration in which the drive circuit 20 is provided with a switch for turning on and off the electrical connection between the light control section 15 and the additional resistor R1, the circuit configuration is simplified.

(3) The voltage generation circuit 25 receives a DC voltage from the DC power source DC, generates a square-wave drive voltage, and this drive voltage is applied to the dimming unit 15 . The square-wave driving voltage has a steeper voltage change from a high potential to a low potential or from a low potential to a high potential compared to the driving voltages having other waveforms. That is, the voltage rises and falls steeply. Therefore, when the application of the drive voltage is stopped at an arbitrary timing, charges tend to remain in the transparent electrode layers 12A and 12B. Therefore, if a light control device using a square-wave drive voltage is provided with a discharge unit, it is highly beneficial to improve the responsiveness of the light transmittance of the light control unit 15 when driving is stopped.

In addition, since the driving voltage is generated from the DC voltage, the light control device can be driven by using a battery such as an on-vehicle battery in a place such as a vehicle where it is difficult to obtain power from a commercial AC power supply.

(4) The control unit 30 turns on the first switch SW1 and the fourth switch SW4, turns off the second switch SW2 and the third switch SW3, turns on the second switch SW2 and the third switch SW3, and turns on the second switch SW2 and the third switch SW3. In addition, by alternately repeating the control of turning off the first switch SW1 and the fourth switch SW4, the voltage generation circuit 25 is made to generate the drive voltage. As a result, a square-wave drive voltage is preferably generated from the DC voltage.

(Second embodiment)
2nd Embodiment of a light control apparatus is described with reference to FIG.6 and FIG.7. The second embodiment differs from the first embodiment in the configuration of the load section included in the drive circuit 20 . In the following, the differences between the second embodiment and the first embodiment will be mainly described, and the same reference numerals will be given to the same configurations as in the first embodiment, and the description thereof will be omitted.

[Configuration of light control device]
As shown in FIG. 6, in the light control device 101 of the second embodiment, the load section 22 included in the drive circuit 20 is composed of an additional resistor R1 and an auxiliary switch SWs. The additional resistor R1 and the auxiliary switch SWs are connected in series.

The auxiliary switch SWs is connected to the control section 30, and the control section 30 controls turning on/off of the auxiliary switch SWs. As the auxiliary switches SWs, for example, semiconductor switches and photoMOS relays are used, like the switches SWm, SW1 to SW4.

[Operation of dimmer]
As shown in FIG. 7, the control period of the light modulation device 101 by the control unit 30 includes the drive period Td and the stop period Ts. The driving period Td is a period during which the main switch SWm is turned on, that is, a period during which the driving voltage is applied. The stop period Ts is a period during which the main switch SWm is turned off. On and off of the main switch SWm are switched, for example, by operating the external switch of the light control device, as described in the first embodiment.

The control unit 30 controls the auxiliary switch SWs in synchronization with the main switch SWm. Specifically, when the main switch SWm is turned on, the auxiliary switch SWs is turned off at the same time, and when the main switch SWm is turned off, the auxiliary switch SWs is turned on at the same time. In other words, the auxiliary switch SWs is turned off while the drive voltage is being applied to the light control section 15, and is turned on when the application of the drive voltage to the light control section 15 is stopped.

When the auxiliary switch SWs is turned off, the conduction between the additional resistor R1 and the light control section 15 is cut off. In other words, no current flows through the additional resistor R1 while the driving voltage is applied to the dimming unit 15 .

On the other hand, when the auxiliary switch SWs is on, the additional resistor R1 and the dimming unit 15 are electrically connected. As a result, a closed circuit is formed in which the additional resistor R1 and the dimming unit 15 are connected in series, as in the first embodiment. Therefore, as in the first embodiment, compared to the case where the additional resistor R1 is not provided, when the application of the drive voltage is stopped, the light control unit 15 changes from the first state to the second state. can shorten the time required for

In the second embodiment, since power consumption of the additional resistor R1 does not occur while the light control device 101 is being driven, there are fewer adverse effects when the resistance value of the additional resistor R1 is reduced as compared with the first embodiment. Therefore, compared with the first embodiment, by making the resistance value of the additional resistor R1 smaller, the time constant τ can be lowered, and the discharge of charges from the transparent electrode layers 12A and 12B can be sped up. That is, in the second embodiment, it is easier to shorten the time required for the light control section 15 to change from the first state to the second state than in the first embodiment.

In the second embodiment, the application of the drive voltage is stopped by turning off the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch in the voltage generating circuit 25 instead of turning off the main switch SWm. It may be realized by turning off all of SW4. In this case, the control unit 30 turns off all of the first to fourth switches SW1 to SW4 and simultaneously turns on the auxiliary switch SWs.

Further, the control unit 30 can turn on the auxiliary switch SWs by turning off the main switch SWm or turning off the first to fourth switches SW1 to SW4 as a trigger, that is, by turning off the application of the driving voltage. good.

In short, the control unit 30 turns off the auxiliary switch SWs while the drive voltage is being applied to the light control unit 15, and simultaneously or immediately after stopping the application of the drive voltage to the light control unit 15. Then, the auxiliary switch SWs should be turned on.

In the second embodiment, the load section 22 and the control section 30 function as a discharge section. The control unit 30 as a discharge unit controls the main switch SWm or the first to fourth switches SW1 to SW4 and the auxiliary switches SWs to discharge the DC power supply DC from the DC power supply in accordance with the stop of the application of the drive voltage. A closed circuit is formed by the additional resistor R1 and the dimming unit 15 which are separated.

As described above, according to the second embodiment, in addition to the effects (1), (3), and (4) of the first embodiment, the following effects can be obtained.
(5) The discharge section includes an auxiliary switch SWs and a control section 30 for controlling on/off of the auxiliary switch SWs. A series circuit is connected in parallel with the dimming unit 15 . The control unit 30 turns off the auxiliary switch SWs while the drive voltage is being applied to the light control unit 15, and turns on the auxiliary switch SWs when the application of the drive voltage to the light control unit 15 is stopped. . According to such a configuration, when the application of the driving voltage is stopped, a closed circuit is formed in which the additional resistor R1 and the dimming section 15 are connected in series, and the charges remaining in the transparent electrode layers 12A and 12B are discharged. . On the other hand, since the power consumption of the additional resistor R1 does not occur while the light control device 101 is being driven, the driving voltage applied to the light control unit 15 is smaller than that of the mode in which the additional resistor R1 is always applied. It is possible to employ an additional resistor R1 having a resistance value. As a result, it is possible to speed up the discharge of charges from the transparent electrode layers 12A and 12B, that is, it is possible to further improve the responsiveness of the light transmittance of the light control section 15 when driving is stopped.

(Third Embodiment)
3rd Embodiment of a light control apparatus is described with reference to FIG.8 and FIG.9. The third embodiment differs from the first embodiment in that the drive circuit does not have a load section and in the manner in which the first to fourth switches SW1 to SW4 are controlled. In the following, differences between the third embodiment and the first embodiment will be mainly described, and configurations similar to those of the first embodiment will be assigned the same reference numerals, and descriptions thereof will be omitted.

[Configuration of light control device]
As shown in FIG. 8, in the light control device 102 of the third embodiment, the drive circuit 23 does not have a load section including the additional resistor R1. The connection between the voltage generation circuit 25 and the light control section 15 is the same as in the first embodiment. The second transparent electrode layer 12B of the light control section 15 is connected to the point P2.

[Operation of dimmer]
As shown in FIG. 9, the control period of the light control device 102 by the control unit 30 includes the drive period Td and the stop period Ts. The driving period Td is a period during which the main switch SWm is turned on, that is, a period during which the driving voltage is applied. The stop period Ts is a period during which the main switch SWm is turned off.

During the drive period Td, the set of the first switch SW1 and the fourth switch SW4 and the set of the second switch SW2 and the third switch SW3 are alternately turned on, as in the first embodiment. That is, the first application period Tn1 and the second application period Tn2 are alternately repeated at a predetermined cycle, so that a square-wave driving voltage is applied to the dimming section 15 .

During the stop period Ts, the first switch SW1 and the third switch SW3 are turned on, and the second switch SW2 and the fourth switch SW4 are turned off. As a result, the first connection point P1 and the second connection point P2 in the drive circuit 23 are directly connected. That is, since the first transparent electrode layer 12A and the second transparent electrode layer 12B of the light control section 15 are connected to cause a short circuit, the charges accumulated in the transparent electrode layers 12A and 12B are quickly discharged.

Therefore, in the circuit of FIG. 8, the first The time required for the transparent electrode layer 12A and the second transparent electrode layer 12B to become equipotential is shortened. Therefore, it is possible to shorten the time required for the light control unit 15 to change from the first state to the second state.

Note that, during the stop period Ts, the control unit 30 turns on the first switch SW1 and the third switch SW3 and turns off the second switch SW2 and the fourth switch SW4 instead of the first control that turns on the second switch SW2 and the fourth switch SW4. and the fourth switch SW4 are turned on, and the first switch SW1 and the third switch SW3 are turned off. Also by this, the first connection point P1 and the second connection point P2 in the drive circuit 23 are directly connected, and the same effects as those described above can be obtained.

Further, the first control or the second control may be started at the same time when the main switch SWm is turned off, or may be started with the turning off of the main switch SWm as a trigger. Furthermore, the main switch SWm may not be provided, and application of the driving voltage may be stopped by starting the first control or the second control.

Further, in the form in which the first control is performed, a resistance element connected in series with these elements may be provided in the closed circuit including the dimming unit 15, the first switch SW1, and the third switch SW3. . Similarly, in the form in which the second control is performed, a closed circuit including the dimming unit 15, the second switch SW2, and the fourth switch SW4 may be provided with a resistive element connected in series with these elements. good. With a configuration in which such a resistive element is provided, it is possible to prevent a large current from instantaneously flowing through the closed circuit due to a short circuit between the first transparent electrode layer 12A and the second transparent electrode layer 12B. Therefore, stable operation of the drive circuit 23 is possible.

In the third embodiment, the controller 30 functions as a discharger. A control unit 30 as a discharge unit discharges the charges remaining in the transparent electrode layers 12A and 12B by controlling the first to fourth switches SW1 to SW4 in accordance with the stop of the application of the driving voltage.

As described above, according to the third embodiment, in addition to the effects (1), (3), and (4) of the first embodiment, the following effects can be obtained.
(6) The controller 30 discharges the charges remaining in the transparent electrode layers 12A and 12B by performing the first control or the second control. According to such a configuration, a discharge portion that discharges charges remaining in the transparent electrode layers 12A and 12B is preferably realized. In addition, since discharge is performed using the voltage generation circuit 25 for generating the drive voltage, the configuration of the drive circuit 23 is simple compared to the form in which a resistance element connected in parallel with the light control unit 15 is provided. is.

(Fourth embodiment)
A fourth embodiment of the light control device will be described with reference to FIG. In the following, differences between the fourth embodiment and the first and third embodiments will be mainly described, and the same reference numerals will be given to the same configurations as those of the first and third embodiments, and the description thereof will be omitted.

As shown in FIG. 10 , in the light control device 103 of the fourth embodiment, the light control sheet 17 includes a light control section 15 and a resistance section 16 . The equivalent circuit of this dimming device matches the circuit shown in FIG.

The resistor section 16 has a resistor layer 14 that constitutes a single conductive film together with the first transparent electrode layer 12A of the dimming section 15 . The transparent support layer 13A supports the first transparent electrode layer 12A and the resistance layer 14. As shown in FIG. For example, the resistive layer 14 has a strip shape, one end in the extending direction of the resistive layer 14 is connected to the first transparent electrode layer 12A, and the other end is connected to the second transparent electrode layer 12B and the drive circuit. 23 is connected to a terminal that connects to a connection point between . The drive circuit 23 does not have a load section including a resistive element, and the transparent electrode layers 12A and 12B are connected to the voltage generation circuit 25, as in the third embodiment.

In the light control sheet 17, a layer extending from the second transparent electrode layer 12B and forming a single conductive film together with the second transparent electrode layer 12B and the light control layer 11 There may be layers extending from and forming a single layer with the light control layer 11 .

Equivalently, in the light control device 103 of the fourth embodiment, similarly to the first embodiment, the resistor is connected in parallel with the light control unit 15, so that the time constant τ becomes small. Therefore, when the application of the drive voltage is stopped, the time required for the first transparent electrode layer 12A and the second transparent electrode layer 12B to have the same electric potential after the electric charge is discharged is shortened. Therefore, it is possible to shorten the time required for the light control unit 15 to change from the first state to the second state.

In the fourth embodiment, since the light control sheet 17 includes the resistance part 16 functioning as a resistor in parallel with the light control part 15 as a part of the sheet, the resistor is incorporated as an element in the drive circuit. The configuration of the drive circuit 23 is simplified as compared with the form in which the drive circuit 23 is provided.

In the fourth embodiment, the resistor section 16 and the control section 30 function as a discharge section. The control unit 30 as a discharge unit controls the main switch SWm or controls the first to fourth switches SW1 to SW4 to switch the light control unit 15, the resistor unit 16, and the DC power supply together with the stop of the application of the drive voltage. A closed circuit is formed in which the dimmer section 15 and the resistor section 16 are connected in series by interrupting the conduction with DC.

As described above, according to the fourth embodiment, in addition to the effects (1), (3), and (4) of the first embodiment, the following effects can be obtained.
(7) The discharge section includes a resistor connected in parallel with the light control section 15 in the path for applying the driving voltage to the light control section 15. In other words, it is equivalently connected in parallel with the light control section 15. resistance. According to such a configuration, the electric charge remaining in the transparent electrode layers 12A and 12B can be discharged by the discharge section. Further, since the light control sheet 17 has the resistor portion 16 functioning as the resistor as a part of the sheet, the configuration of the drive circuit 23 is smaller than that in which the resistor is incorporated as an element in the drive circuit. becomes simpler.

(Modification)
Each of the above embodiments can be modified and implemented as follows.
The drive voltage may be an AC voltage, that is, a voltage whose direction changes in a predetermined cycle, and is not limited to a rectangular wave, and a voltage having a sine wave or triangular wave may be used as the drive voltage. In addition, the power source may be an AC power supply, an AC voltage supplied from the AC power supply may be applied to the light control sheet as a driving voltage, and the AC voltage supplied from the AC power supply may be transformed, modulated, etc. may be used as the driving voltage. Note that the light control device may include a power supply as a component of the device.

When a drive voltage with a waveform such as a sine wave or a triangular wave in which the magnitude of the voltage changes gradually near 0 V is used, the timing at which the magnitude of the voltage becomes 0 V can be detected by using a zero-cross detection circuit. Easy. Therefore, by stopping the application of the drive voltage at the timing detected by the zero-cross detection circuit, the charge remaining on the transparent electrode layers 12A and 12B is reduced, thereby improving the responsiveness of the light transmittance of the light control section 15. It is possible to raise it. On the other hand, if the discharge units of the first, second, and fourth embodiments are applied to a configuration using a sine wave or triangular wave drive voltage, the light control unit 15 can be adjusted without using the zero cross detection circuit. Responsiveness of light transmittance can be enhanced. Note that the zero-cross detection circuit and the discharge section may be used together.

The discharge section only needs to have a function of discharging charges remaining in the transparent electrode layers 12A and 12B when application of the drive voltage to the dimming section 15 is stopped. It may differ from each embodiment. For example, the connection of the circuit may be switched so that each of the transparent electrode layers 12A and 12B becomes the ground potential when the application of the drive voltage is stopped.

- Mechanical switches or mechanical relays may be used as the switches SWm, SW1 to SW4, and SWs.
- The light control part 15 of the light control sheet may include other layers in addition to the light control layer 11, the transparent electrode layers 12A and 12B, and the transparent support layers 13A and 13B. The other layers are layers for protecting the light control layer 11 and the transparent electrode layers 12A and 12B, such as a layer having an ultraviolet barrier function, and contribute to control of light transmittance in the light control section 15. and a layer that enhances properties such as strength and heat resistance of the light control sheet.

Further, the light control section 15 may include a pair of alignment layers sandwiching the light control layer 11 between the light control layer 11 and the transparent electrode layers 12A and 12B. The alignment layer is a layer that controls the alignment of the liquid crystal molecules included in the light control layer 11, and aligns the liquid crystal molecules in a predetermined direction when no driving voltage is applied. In the configuration including the alignment layer, when the drive voltage is applied to the transparent electrode layers 12A and 12B, the light control portion is in the first state of being opaque, and when the drive voltage is not applied to the transparent electrode layers 12A and 12B. , the second state in which the dimming portion 15 is transparent.

Further, the light control layer 11 may contain a dye having a predetermined color that does not hinder the movement of liquid crystal molecules according to the magnitude of the voltage applied to the light control layer 11 . According to such a configuration, the dimming section 15 having a predetermined color is realized.

Co... Capacitor, DC... DC power supply, Rh... High resistance, Rl... Low resistance, R1... Additional resistance, SWm... Main switch, SW1 to SW4... First to fourth switches, SWs... Auxiliary switch, 10, 17... Adjustment Optical sheet 11... Light control layer 12A, 12B... Transparent electrode layer 13A, 13B... Transparent support layer 14... Resistance layer 15... Light control part 16... Resistance part 20, 23... Drive circuit 21, 22... load section, 25... voltage generation circuit, 30... control section, 100 to 103... light control device.

Claims (3)

a light control section including a light control layer containing a liquid crystal composition and a pair of transparent electrode layers sandwiching the light control layer, the light control section to which a drive voltage that is an AC voltage is applied;
a discharge unit that discharges the charge remaining in the transparent electrode layer in accordance with the stop of the application of the driving voltage to the light control unit ;
the discharge unit includes a resistance unit functioning as a resistor connected in parallel with the light control unit in a path for applying the drive voltage to the light control unit;
The light control section and the discharge section form a light control sheet, and the resistance section has a resistance layer forming a single conductive film together with one of the pair of transparent electrode layers.
dimmer. The light control device according to claim 1, further comprising a voltage generating circuit that receives supply of a DC voltage and generates the rectangular wave drive voltage. the voltage generation circuit includes a first switch, a second switch, a third switch, and a fourth switch;
the first switch and the second switch are connected in series such that the first switch is connected to the positive side of a power supply and the second switch is connected to the negative side of the power supply;
the third switch and the fourth switch are connected in series such that the third switch is connected to the positive side of a power supply and the fourth switch is connected to the negative side of the power supply;
the set of the first switch and the second switch and the set of the third switch and the fourth switch are connected in parallel to a power supply;
One of the pair of transparent electrode layers is connected to the connection point between the first switch and the second switch, and the pair of transparent electrode layers is connected to the connection point between the third switch and the fourth switch. is connected to the other of the transparent electrode layers of
Equipped with a control unit that controls the on/off of each switch,
The control unit turns on the first switch and the fourth switch and turns off the second switch and the third switch, turns on the second switch and the third switch, and turns on the The light control device according to claim 2, wherein the drive voltage is generated by alternately repeating control to turn off the first switch and the fourth switch.

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