JP7400370B2 - Anomaly detection means, anomaly detection method, and anomaly detection program - Google Patents

Description

The present invention relates to an abnormality detection means, an abnormality detection method, and an abnormality detection program used in a light control device.

The light control device includes a light control layer sandwiched between a pair of transparent electrodes. The light control layer contains a liquid crystal composition and changes from transparent to opaque in response to changes in the voltage between transparent electrodes. A drive circuit that drives the light control layer applies an alternating current voltage between transparent electrodes to extend the life of the light control layer (for example, see Patent Document 1).

Types of driving the light control layer are classified into normal type and reverse type. In normal type driving, the light control layer is opaque when electricity is not applied, and the light control layer is transparent when electricity is applied. The normal type drive is suitable for applications such as screens that frequently require light shielding properties. In the reverse type drive, the light control layer is transparent when no electricity is applied, and the light control layer is opaque when electricity is applied (for example, see Patent Document 2). The reverse type drive is suitable for application to building materials etc. that require safety due to transparency in an emergency.

JP2018-091986A Japanese Patent Application Publication No. 2000-321562

By the way, in the above-mentioned light control device, the voltage level applied between the transparent electrodes may reach 10 volts or more, so from the viewpoint of protecting the drive circuit and saving power, it is necessary to prevent abnormalities in the light control device. When an abnormality occurs, it is required to immediately detect that an abnormality has occurred.

An object of the present invention is to provide an abnormality detection means, an abnormality detection method, and an abnormality detection program that are capable of detecting an abnormality in a light control device.

In order to solve the above problems, the present invention provides an abnormality detection means used in a light control device, wherein the light control device includes a light control layer located between transparent electrodes, and voltage pulses of mutually different polarities. The abnormality detection means includes a drive voltage generation circuit that applies a drive voltage that alternately repeats the following between the transparent electrodes, and the abnormality detection means determines whether the current between the transparent electrodes in the determination target period is equal to or higher than a threshold for overcurrent determination. an abnormality determination means for determining that a current equal to or higher than a threshold for overcurrent determination is abnormal; A timing control unit that sets a predetermined period until the voltage becomes less than a determination threshold as a non-target period, and sets the start timing of the determination target period to when the non-target period has elapsed from the application timing of the voltage pulse. This is an abnormality detection means characterized by the following.

With this configuration, the current spike that occurs at the beginning of the non-target period is excluded from the determination by the abnormality determination means, and erroneous determination caused by the current spike is suppressed, so dimming is reduced. This has the effect of improving the accuracy of detecting abnormalities occurring in the device.

Further, the present invention provides the abnormality detection means described above, wherein the timing control section controls the application timing of the voltage pulse.

With this configuration, the present invention allows a single common timing control unit to control the timing at which current spikes begin to occur (timing to apply voltage pulses) and the timing at which detection other than spikes begins (timing to start determination target period). This has the effect of making it possible to improve the accuracy of excluding current spikes caused by the application of voltage pulses from the determination target.

Further, the present invention provides the above abnormality detection means, wherein the abnormality determination means includes:
a current detection circuit that detects the current between the transparent electrodes;
a current detection mask circuit that partially masks the detection signal of the current detection circuit;
determining whether a masked detection signal by the current detection mask circuit is equal to or greater than the overcurrent determination threshold, and determining that detection of a current equal to or greater than the overcurrent determination threshold is abnormal; comprising a circuit;
The timing control section includes:
The abnormality detection means is characterized in that a period masked by the current detection mask circuit is the non-target period.

With this configuration, the present invention has the effect that the abnormality in the light control device can be detected even when the abnormality in the light control device occurs over a non-target period.

The present invention also provides the above abnormality detection means, comprising:
The abnormality determination means further includes a peak hold circuit that holds the maximum value of the detection signal during the determination target period,
The determination circuit determines whether the maximum value held by the peak hold circuit is equal to or greater than the overcurrent determination threshold, and determines that the detection of the maximum value equal to or greater than the overcurrent determination threshold is abnormal. It is determined that there is
The timing control section is an abnormality detection means characterized in that the peak hold circuit is reset immediately before the application timing.

In the present invention, with this configuration, the maximum value of the detection signal detected during the determination target period is held in the peak hold circuit. Therefore, compared to a configuration in which the determination as to whether the detection signal is equal to or greater than the overcurrent determination threshold is performed sequentially in the order of detection, the number of determinations can be reduced.

The present invention also provides the above abnormality detection means, comprising:
The light control device includes a booster circuit that converts a voltage level of a constant voltage power supply to a voltage level of the voltage pulse, and a drive voltage generation circuit that generates the drive voltage from the output level of the booster circuit,
The timing control unit controls the output timing of the drive voltage generation circuit to apply the drive voltage between the transparent electrodes, and stops application of the drive voltage when it is determined that the abnormality occurs. This is an abnormality detection means characterized by the following.

With this configuration, the present invention has the effect of suppressing an increase in power consumption due to an abnormality in the light control device.

The present invention also provides the above abnormality detection means, comprising:
The abnormality determining means includes a current detection circuit that detects a current between the transparent electrodes,
The drive voltage generation circuit includes a full bridge circuit including a first switch, a second switch, a third switch, and a fourth switch, the first switch and the third switch connected in series, and the full bridge circuit connected in series with the first switch and the third switch. a second switch and the fourth switch are connected in parallel;
A connecting portion between the first switch and the second switch is connected to an output level of the booster circuit,
A connection portion between the third switch and the fourth switch is connected to a ground level via the current detection circuit,
A connecting portion between the first switch and the third switch is connected to one of the transparent electrodes,
A connecting portion between the second switch and the fourth switch is connected to the other transparent electrode,
The timing control section is configured to turn on the first switch and the fourth switch, turn off the second switch and the third switch, and turn on the first switch and the fourth switch. applying the driving voltage between the transparent electrodes by alternately repeating turning off the switch and turning on the second switch and the third switch;
The current detection circuit is an abnormality detection means characterized in that it detects a current flowing from a connecting portion between the third switch and the fourth switch to a ground level as the current between the transparent electrodes.

In the present invention, with this configuration, the connecting portion between the first switch and the third switch is connected to one transparent electrode. A connecting portion between the second switch and the fourth switch is connected to the other transparent electrode. Then, the connection destination of the connection portion between the third switch and the fourth switch is switched between one transparent electrode and the other transparent electrode. That is, the path through which the current detected by the detection circuit flows is switched between a path connecting one transparent electrode and the ground level and a path connecting the other transparent electrode and the ground level.

Here, when the polarity of the voltage pulse applied between the transparent electrodes changes, the direction in which the current flows between the transparent electrodes also reverses. In this regard, with the above configuration, the object detected by the detection circuit changes as described above as the polarity of the voltage pulse changes. As a result, even if the direction of current flow is reversed between the transparent electrodes, the current detected by the detection circuit will flow in the same direction toward the ground level, so a simple configuration can be used to detect current flowing in one direction. However, it has the advantage that it can be adopted in a detection circuit.

The present invention also provides the above abnormality detection means, comprising:
The abnormality detection means further comprises an overcurrent protection circuit that blows a fuse to disconnect the booster circuit from the constant voltage power source when the output current of the constant voltage power source is equal to or higher than a predetermined value. .

The present invention also provides the above abnormality detection means, comprising:
The abnormality detection means further comprises an abnormality notification means for notifying the outside that an abnormality has occurred in the light control device when the abnormality is determined.

With this configuration, the present invention notifies the outside that an abnormality has occurred in the light control device. Therefore, it is possible to determine whether an abnormality that is visible from the outside is caused by an abnormality occurring in the circuit for driving the light control device or an abnormality occurring in the light control device itself. As a result, there is an effect that it becomes easier to deal with abnormalities related to the light control device.

The present invention also provides the above abnormality detection means, comprising:
The earth leakage abnormality detection means is provided with an earth leakage abnormality detection means,
a source current detection circuit that detects a source current flowing into a power supply side terminal of the drive voltage generation circuit;
a sink current detection circuit that detects a sink current flowing out from a ground level side terminal of the drive voltage generation circuit;
a difference detection circuit that detects a difference between the source current and the sink current;
The abnormality detection means is characterized by having an earth leakage determination circuit that compares the detected difference value with a threshold value for earth leakage determination to detect an earth leakage.

Further, the present invention provides the above-mentioned abnormality detecting means, which is characterized by having a circuit that allows the electric leakage determination threshold to be made variable and freely set.

Further, the present invention provides an abnormality detection means as described above, characterized in that it has an abnormality notification means that distinguishes and notifies abnormality determination due to abnormal overcurrent and earth leakage determination by earth leakage abnormality detection means. It is a means.

The present invention also provides an abnormality detection method for detecting an abnormality occurring in a light control device, comprising:
The light control device includes a light control layer located between transparent electrodes, and a drive voltage generation circuit applies a drive voltage between the transparent electrodes that alternately repeats voltage pulses of different polarities,
When a non-target period has elapsed, which is a predetermined period from the application timing of the voltage pulse until the spike of current between the transparent electrodes that occurs at the application timing becomes less than the threshold for overcurrent determination, The abnormality detection method is characterized in that it is determined whether or not the current is equal to or higher than the overcurrent determination threshold, and the detection of a current equal to or higher than the overcurrent determination threshold is determined to be abnormal. .

The present invention also provides an abnormality detection method for detecting an abnormality occurring in a light control device, comprising:
The light control device includes a light control layer located between transparent electrodes, and a drive voltage generation circuit applies a drive voltage between the transparent electrodes that alternately repeats voltage pulses of different polarities,
The earth leakage detection means is
detecting a source current flowing into a power supply side terminal of the drive voltage generation circuit;
detecting a sink current flowing from a ground level side terminal of the drive voltage generation circuit;
This abnormality detection method is characterized in that an earth leakage abnormality is determined by comparing a value obtained by detecting a difference between the source current and the sink current with a threshold value for earth leakage determination.

The present invention also provides an abnormality detection program that causes an abnormality detection means to detect an abnormality that occurs in a light control device,
The light control device includes a light control layer located between transparent electrodes,
a program that controls timing for applying a drive voltage to a drive voltage generation circuit that alternately repeats voltage pulses of mutually different polarities between the transparent electrodes;
When a non-target period has elapsed, which is a predetermined period from the application timing of the voltage pulse until the spike of current between the transparent electrodes that occurs at the application timing becomes less than the threshold for overcurrent determination, a program that controls timing as a start timing of a determination target period for determining whether or not the current is equal to or higher than the overcurrent determination threshold;
The abnormality detection means determines whether or not the current between the transparent electrodes during the determination target period is equal to or higher than an overcurrent determination threshold, and detects that a current equal to or higher than the overcurrent determination threshold is detected as abnormal. This is an abnormality detection program characterized by having a program that makes a determination.

The present invention also provides the above abnormality detection program, comprising:
The abnormality detection means has a circuit that detects the current between the transparent electrodes with a current detection circuit and converts it into digital data with an A/D converter,
A program that distinguishes between a predetermined non-target period and a determination target period other than the non-target period until a current spike between the transparent electrodes that occurs at the timing of applying the voltage pulse becomes less than the overcurrent determination threshold; ,
A program that performs mask processing to process only the digital data of the current in the determination target period from the digital data of the current between the transparent electrodes;
a program that performs peak hold processing that extracts and stores the maximum value of digital current data during the determination target period;
The abnormality detection program includes a program that compares the maximum value with an overcurrent determination threshold and performs an abnormality determination process when the maximum value is equal to or greater than the overcurrent determination threshold.

The present invention also provides the above abnormality detection program, comprising:
The abnormality detection means
A circuit that detects a source current flowing into a power supply side terminal of the drive voltage generation circuit with a source current detection circuit and converts it into digital data with an A/D converter,
a circuit for detecting a sink current flowing out from a terminal on the ground level side of the drive voltage generation circuit with a sink current detection circuit and converting it into digital data with an A/D converter;
a program that calculates difference data between the digital data of the source current and the digital data of the sink current;
The abnormality detection program is characterized by having a program that compares the difference data with threshold data for earth leakage determination, and performs earth leakage determination processing when the difference data exceeds the threshold data for earth leakage determination.

According to the present invention, a spike-like current that occurs at the timing of applying a voltage pulse is excluded from the determination by the abnormality determining means. The spike-like current caused by the application of the voltage pulse is not determined to be a current due to an abnormality occurring in the light control device, but is treated as a normal current.

With this configuration, the current spike that occurs at the beginning of the non-target period is excluded from the determination by the abnormality determination means, and erroneous determination caused by the current spike is suppressed, so dimming is reduced. This has the effect of improving the accuracy of detecting abnormalities occurring in the device.

Further, according to the above configuration, the timing control unit sets the determination target period each time a voltage pulse is applied between the transparent electrodes. In each determination period, it is determined whether the current between the transparent electrodes is equal to or higher than the overcurrent determination threshold, and it is determined that it is abnormal if the current between the transparent electrodes is equal to or higher than the overcurrent determination threshold. Ru. Furthermore, since the presence or absence of an abnormality in the light control device is determined based on the application period of the voltage pulse, there is an effect that if an abnormality occurs in the light control device, the occurrence of the abnormality can be immediately detected.

Further, the present invention has a source current detection circuit and a sink current detection circuit, and has a difference detection circuit that compares the source current detected by the source current detection circuit and the sink current detected by the sink current detection circuit, and An earth leakage abnormality detection means is provided which has an earth leakage determination circuit that determines whether or not there is an earth leakage based on the output of the detection circuit.

This configuration has the effect of detecting an abnormal current when a leakage occurs and determining an abnormality in the light control device.

FIG. 2 is a block diagram showing the configuration of an abnormality detection means according to the first embodiment of the present invention together with a light control device. FIG. 2 is a circuit diagram incorporating an abnormality detection means according to the first embodiment of the present invention. (a), (b), and (c) are timing charts showing the operation of the abnormality detection method performed by the abnormality detection means of the first embodiment of the present invention using the transition of a detection signal. FIG. 7 is a block diagram showing the configuration of an embodiment of an earth leakage abnormality detection means according to a second embodiment of the present invention together with a light control device. FIG. 7 is a circuit block diagram incorporating an earth leakage abnormality detection means according to a second embodiment of the present invention. FIG. 7 is a circuit diagram incorporating an earth leakage abnormality detection means according to a second embodiment of the present invention. (a), (b), and (c) are timing charts showing the operation of the earth leakage detection method performed by the earth leakage abnormality detection means of the second embodiment of the present invention using the transition of a detection signal.

<First embodiment>
A first embodiment of a light control device of the present invention will be described below with reference to FIGS. 1 to 3. As shown in FIG. 1, the light control device of this embodiment includes a light control film 10 and a drive circuit 20 that drives the light control film, and the drive circuit 20 includes an abnormality detection means 30.

(Dimmer film 10)
The light control film 10 used in the light control device of this embodiment is attached to a window of a moving body such as a vehicle or an aircraft. Further, the light control film 10 is pasted on windows of buildings such as houses, stations, and airports, partitions installed in offices, etc., and show windows installed in stores and the like.

The object to which the light control film 10 is attached has various shapes such as a planar shape, a curved surface shape, and an irregular shape. The shape of the light control film 10 can be changed to a geometric shape other than a rectangle, a sheet shape such as an irregular shape, or a plate shape.

The type of light control film 10 is a liquid crystal type or an electrochromic type. The liquid crystal type reversibly changes the orientation of the liquid crystal molecules between a light scattering state and a light transmitting state depending on the magnitude of the electric field applied to the liquid crystal molecules. In the electrochromic type, a redox reaction reversibly proceeds depending on the magnitude of the voltage applied to the light control film 10, and the light absorption rate changes as the redox reaction progresses. Since the abnormality detection for the liquid crystal type light control film 10 and the abnormality detection for the electrochromic type light control film 10 are the same, an example in which the type of the light control film 10 is the liquid crystal type will be shown below.

The light control film 10 includes a first transparent electrode 11, a second transparent electrode 12, and a light control layer 13, as shown in FIG. Each transparent electrode 11, 12 has visible light transparency and electrical conductivity. The material constituting each transparent electrode 11, 12 is selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), and a silver alloy thin film. It is one of the types.

The light control layer 13 contains a liquid crystal composition. Examples of liquid crystal molecules contained in the liquid crystal composition include Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoic acid ester-based, tolan-based, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, It is a type selected from the group consisting of dioxane series.

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

The light control layer 13 can be regarded as a parallel circuit of a capacitive component and a resistive component. The light control layer 13 changes the alignment direction of liquid crystal molecules upon application of a driving voltage. Changing the alignment direction changes the degree of scattering, degree of absorption, and degree of transmission of visible light incident on the light control layer 13.

The type of light control film 10 is either a normal type or a reverse type. The normal type achieves high transmittance by applying a driving voltage. In addition, the normal type achieves low transmittance by stopping the application of the driving voltage. On the other hand, the reverse type achieves low transmittance by applying a driving voltage. Furthermore, the reverse type achieves high transmittance by stopping the application of the driving voltage.

(Drive circuit 20)
The light control device includes a drive circuit 20. The drive circuit 20 includes a constant voltage power supply 21, an overcurrent protection circuit 22, a booster circuit 23, a control power supply circuit 24, a timing control circuit 26, an input means 25, a drive voltage generation circuit 27 consisting of a full bridge circuit, and an abnormality detection circuit. Means 30 is provided.

The drive circuit 20 changes the transmittance of the light control layer 13 of the light control film 10 by changing the applied voltage applied to the light control film 10 or by changing the time for applying the applied voltage to the light control film 10. change.

Possible failure modes of the light control film 10 include a short circuit between the upper and lower films at the ends or within the plane of the light control film 10, or an open lead wire or film connection. In the case of an open failure, no fault current will flow and only a predetermined voltage will be output, so no major accident will occur. However, in the case of a short-circuit failure, an excessive short-circuit current may flow and burn out the light control layer 13 of the light control film 10, each of the transparent electrodes 11 and 12, or nearby combustible materials.

When a failure occurs, a fuse provided in the overcurrent protection circuit 22 of the drive circuit 20 blows, cutting off excessive current from flowing through the circuit. However, the fusing current of a fusing type fuse is generally set to be large so that it does not easily blow out due to spike current of normal current.

However, when a failure occurs in the light control film 10, the fuse provided in the overcurrent protection circuit 22 has the disadvantage that the circuit cannot be immediately shut off, and there is a problem that needs to be improved. .

In order to solve this problem, the present embodiment uses a light control device including an abnormality detection means 30 as shown in FIG. 1. This embodiment has a configuration in which an abnormality detection means 30 is added to the drive circuit 20, as shown in the circuit diagram of FIG. As shown in FIG. 2, the abnormality detection means 30 connects a current detection circuit 31 to a drive voltage generation circuit 27 controlled by a timing control circuit 26, and processes the current detection signal Ia measured by the current detection circuit 31. to detect overcurrent abnormality.

Considering the waveform of the current that occurs during an abnormality as shown in FIG. 3, the abnormality detection means 30 uses a current detection mask circuit 32 to detect a short circuit between the current flowing during normal times and the transparent electrodes 11 and 12 of the light control film 10 due to a short circuit failure. To identify the overcurrent that flows when there is a problem, etc., and reliably determine the failure of the light control film.

(Timing control circuit 26 and abnormality detection means 30)
The control means of the drive circuit 20 includes a central processing unit and a memory. The control means is not limited to one that processes all the various processes using software. For example, the control means may include dedicated hardware (Application Specific Integrated Circuit: ASIC) that executes at least some of the various types of processing. The control means is configured as a circuit including one or more dedicated hardware circuits such as an ASIC, one or more processors (microcomputers) operating according to a computer program (software), or a combination thereof.

The control means of the drive circuit 20 stores a program for causing the timing control circuit 26 to control the drive voltage and an abnormality detection program for the abnormality detection means 30 in a readable medium, and stores the program for controlling the drive voltage and the abnormality detection program. controls the operation of the timing control circuit 26.

The control means reads the abnormality detection program stored in the readable medium and operates the abnormality detection means 30 to perform abnormality detection processing. The abnormality detection means 30 causes the timing control circuit 26 to generate a mask signal SIGM for determining the non-target period, and inputs the generated mask signal SIGM to the current detection mask circuit 32.

The abnormality detection means 30 includes a current detection circuit 31, a current detection mask circuit 32, a peak hold circuit 33, an abnormality determination circuit 34, and an abnormality notification means 35 in addition to the function of causing the timing control circuit 26 to generate a mask signal SIGM.

(Each circuit of drive circuit 20)
The constant voltage power supply 21 is a power supply mounted on a moving object or a power supply provided in a building. Constant voltage power supply 21 outputs a DC constant voltage. The DC constant voltage is, for example, 12V.

The overcurrent protection circuit 22 is connected to the constant voltage power supply 21 and the booster circuit 23 , and inputs the DC constant voltage output from the constant voltage power supply 21 to the booster circuit 23 . The overcurrent protection circuit 22 is connected to the constant voltage power supply 21 and the control power supply circuit 24, and inputs the DC constant voltage output from the constant voltage power supply 21 to the control power supply circuit 24. The overcurrent protection circuit 22 blows a fuse to disconnect the constant voltage power supply 21 from the booster circuit 23 and the control power supply circuit 24 when the output current of the constant voltage power supply 21 is equal to or higher than a predetermined value. The fuse included in the overcurrent protection circuit 22 has a large fusing current so that it will not be blown by a normal current spike.

The fuse included in the overcurrent protection circuit 22 is set to have a large blowing current so that it will not blow due to normal current spikes. On the other hand, a fuse with a large blowing current is difficult to immediately disconnect the constant voltage power source 21 and the booster circuit 23 when the constant voltage power source 21 outputs an overcurrent. In this regard, with the configuration described above, application of the drive voltage is stopped when it is determined that the light control device is abnormal. That is, various circuits for driving the light control device are protected against abnormalities in the light control device itself by the control performed by the timing control circuit 26. Various circuits for driving the light control device are appropriately protected against abnormalities in other circuits by the overcurrent protection circuit 22 equipped with a fuse having a large blowing current.

The booster circuit 23 boosts the voltage level of the DC constant voltage output by the constant voltage power supply 21 to a voltage level for generating a drive voltage. As for the drive voltage applied between the first transparent electrode 11 and the second transparent electrode 12, the drive voltage generation circuit 27 applies voltage pulses of mutually different polarities (see FIG. 3) alternately and repeatedly. The voltage level for generating the driving voltage is a voltage level that can change the orientation of liquid crystal molecules by applying the driving voltage, and is, for example, 50V.

The control power supply circuit 24 steps down the voltage level of the DC constant voltage output from the constant voltage power supply 21 to a voltage level for driving the timing control circuit 26 and the abnormality detection means 30. The voltage level for driving the timing control circuit 26 and the abnormality detection means 30 is, for example, 3.3V.

The input means 25 includes an input interface such as an alternate type mechanical switch or a capacitive touch panel switch. The input means 25 receives a switch operation for driving the light control device and inputs an operation signal corresponding to the operation to the timing control circuit 26. The input means 25 receives a switch operation for stopping the driving of the light control device, and inputs an operation signal corresponding to the operation to the timing control circuit 26. The timing control circuit 26 receives input of each operation signal and executes processing according to each operation signal.

(Drive voltage generation circuit 27)
As shown in FIG. 2, the drive voltage generation circuit 27 includes a full bridge circuit including a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The first switch Q1 is a p-channel transistor. The third switch Q3 is an n-channel transistor. The first switch Q1 and the third switch Q3 constitute a CMOS transistor. Further, the second switch Q2 is a p-channel transistor. The fourth switch Q4 is an n-channel transistor. The second switch Q2 and the fourth switch Q4 constitute a CMOS transistor.

Note that if the timing control circuit 26 includes a dedicated IC that can shift the voltage level of the gate signal of the transistor to the level of the source terminal of the first switch Q1 and the second switch Q2, the first switch It is also possible to use n-channel transistors for Q1 and the second switch Q2.

The first switch Q1 and the third switch Q3 are connected in series. The second switch Q2 and the fourth switch Q4 are connected in series. The first switch Q1 and third switch Q3 connected in series are connected in parallel, and the second switch Q2 and fourth switch Q4 connected in series are connected in parallel.

The first terminals of the first switch Q1 and the second switch Q2 are connected to the power supply side terminal of the drive voltage generation circuit 27 connected to the output end of the booster circuit 23, and the current detection circuit 31 installed on the ground level side The second terminals of the third switch Q3 and the fourth switch Q4 are connected to the terminal of the drive voltage generating circuit 27, which is connected to the terminal of the drive voltage generating circuit 27.

The second terminal of the first switch Q1 and the first terminal of the third switch Q3 are connected to the first transparent electrode 11. The second terminal of the second switch Q2 and the first terminal of the fourth switch Q4 are connected to the second transparent electrode 12.

In this way, the ground level side terminal to which the second terminals of the third switch Q3 and the fourth switch Q4 of the drive voltage generation circuit 27 are connected is connected to the ground level via the current detection circuit 31.

The timing control circuit 26 controls the output timing of the drive voltage generation circuit 27 and applies a drive voltage between the first transparent electrode 11 and the second transparent electrode 12.

That is, the timing control circuit 26 turns on the first switch Q1 and the fourth switch Q4, and turns off the second switch Q2 and the third switch Q3, thereby grounding the first transparent electrode 11. A voltage pulse is applied between the transparent electrodes 11 and 12 so that the second transparent electrode 12 reaches the output level of the booster circuit 23 .

Further, the timing control circuit 26 turns off the first switch Q1 and the fourth switch Q4, and turns on the second switch Q2 and the third switch Q3, whereby the first transparent electrode 11 is boosted. A voltage pulse that is at the output level of the circuit 23 and at which the second transparent electrode 12 is at the ground level is applied between the transparent electrodes 11 and 12.

Then, the timing control circuit 26 alternately and repeatedly applies the output level of the booster circuit 23 to the first transparent electrode 11 and the second transparent electrode 12. Further, the timing control circuit 26 controls all the switches Q1, Q1, and Q1 between the period when the first transparent electrode 11 is at the output level of the booster circuit 23 and the period when the second transparent electrode 12 is at the output level of the booster circuit 23. There is a period in which Q2, Q3, and Q4 are turned off and the transparent electrodes 11 and 12 are in a floating state.

(Current spike between transparent electrodes 11 and 12)
The rise of the voltage pulse when the drive voltage generation circuit 27 of this embodiment switches the switches Q1, Q2, Q3, and Q4 to alternately and repeatedly apply voltage pulses of mutually different polarities between the transparent electrodes 11 and 12, Alternatively, at the time of falling, due to the capacitance between the transparent electrodes 11 and 12 of the light control film 10, as shown in FIG. 3(b), the voltage level V11 of the first transparent electrode 11 is switched to a positive voltage. spike-like currents occur when switching to a negative voltage and when switching to a negative voltage.

(Current detection circuit 31 of abnormality detection means 30)
The current detection circuit 31 is connected to the connection between the third switch Q3 and the fourth switch Q4 and to the ground level. The current detection circuit 31 detects the current flowing from the connection between the third switch Q3 and the fourth switch Q4 to the ground level. The current flowing from the connection between the third switch Q3 and the fourth switch Q4 to the ground level is treated as a current flowing between the first transparent electrode 11 and the second transparent electrode 12.

Note that, as described above, the connection portion between the second switch Q2 and the fourth switch Q4 is connected to the first transparent electrode. A connecting portion between the first switch Q1 and the third switch Q3 is connected to the second transparent electrode 12. Then, when the driving voltage is applied to the light control film 10, the connection destination of the connection portion between the third switch Q3 and the fourth switch Q4 is switched to the first transparent electrode 11 and the second transparent electrode 12. That is, the path through which the current detected by the current detection circuit 31 flows is switched between a path connecting the first transparent electrode 11 and the ground level and a path connecting the second transparent electrode 12 and the ground level.

Here, when the polarity of the voltage pulse applied between the transparent electrodes 11 and 12 is changed, the direction in which the current flows between the transparent electrodes 11 and 12 is also reversed. In this regard, the object detected by the current detection circuit 31 changes as described above as the polarity of the voltage pulse changes. As a result, even if the direction of current flow is reversed between the transparent electrodes 11 and 12, the direction of current flow detected by the current detection circuit 31 remains constant. Therefore, a simple configuration that detects a current flowing in one direction can be adopted as the current detection circuit 31.

(Current detection mask circuit 32 of abnormality detection means 30)
The current detection mask circuit 32 is connected to the current detection circuit 31. The current detection mask circuit 32 masks a portion of the detection signal Ia (detected current) sequentially outputted by the current detection circuit 31, and outputs an extracted signal Im that is the masked detection signal Ia. During the masking period, the current detection mask circuit 32 outputs an extraction signal Im indicating that the current between the transparent electrodes 11 and 12 is less than the overcurrent determination threshold Ith. The current detection mask circuit 32 outputs an extraction signal Im corresponding to the detection signal Ia during a period in which masking is not performed.

The abnormality detection means 30 uses the mask signal SIGM generated by the timing control circuit 26 to control the period during which the current detection mask circuit 32 performs masking. The period masked by the current detection mask circuit 32 is a non-target period. The period in which the current detection mask circuit 32 does not mask is the determination target period. The non-target period, which is the period masked by the current detection mask circuit 32, is determined by estimating the period during which the spike is less than the threshold value.

The abnormality detection means 30 causes the timing control circuit 26 to generate a mask signal SIGM for determining the non-target period, and inputs the mask signal SIGM to the current detection mask circuit 32. The rise of the mask signal SIGM is the timing at which the non-target period starts and the timing at which the determination target period ends. The fall of the mask signal SIGM is the timing at which the non-target period ends and the timing at which the determination target period begins.

The timing control circuit 26 starts the non-target period from the timing at which the voltage pulse is applied (application timing). The timing control circuit 26 ends the non-target period after the current spike between the transparent electrodes 11 and 12 that occurs at the application timing becomes less than the threshold value Ith. That is, the timing control circuit 26 ends the determination target period at the voltage pulse application timing, starts the non-target period from the end of the determination target period, and then starts the determination target period from the end of the non-target period. Start again.

A spike that occurs in the current flowing between the transparent electrodes 11 and 12 at the timing of applying the voltage pulse is a waveform disturbance due to the normal current. The period until the spike due to the normal current becomes less than the overcurrent determination threshold Ith is predetermined, for example, based on the capacitance component and resistance component of the light control film 10. Alternatively, the period until a spike due to normal current becomes less than the overcurrent determination threshold Ith is predetermined, for example, based on test research using the light control film 10.

A current equal to or higher than the overcurrent determination threshold Ith is an abnormal overcurrent flowing between the transparent electrodes 11 and 12, excluding spikes in normal current. The overcurrent flowing between the transparent electrodes 11 and 12 is caused by contact between the first transparent electrode 11 and the second transparent electrode 12, etc. The overcurrent determination threshold Ith is a value at which it is estimated that an overcurrent is flowing between the transparent electrodes 11 and 12, and is predetermined based on the state in which a short circuit has occurred between the transparent electrodes 11 and 12. .

(Peak hold circuit 33 of abnormality detection means 30)
The peak hold circuit 33 is connected to the current detection mask circuit 32. The peak hold circuit 33 holds the maximum value of the extracted signal Im output from the current detection mask circuit 32. The peak hold circuit 33 outputs the maximum value held as a sample signal Is. The maximum value held by the peak hold circuit 33 continues to be updated from when the reset signal SIGR is input to the peak hold circuit 33 until the reset signal SIGR is input to the peak hold circuit 33 again.

The timing control circuit 26 controls the timing at which the peak hold circuit 33 is reset. The timing control circuit 26 resets the peak hold circuit 33 within the non-target period determined by the timing control circuit 26.

It is desirable that these current detection circuit 31, current detection mask circuit 32, and peak hold circuit 33 be constructed from analog circuits. By configuring these circuits with analog circuits, the time required from outputting the detection signal Ia to outputting the sample signal Is can be shortened, and as a result, abnormalities in the light control device can be detected in real time. There is.

(Abnormality determination circuit 34 of abnormality detection means 30)
The abnormality determination circuit 34 is connected to the peak hold circuit 33. The abnormality determination circuit 34 uses the sample signal Is output from the peak hold circuit 33 to determine whether the maximum value held by the peak hold circuit 33 is greater than or equal to the overcurrent determination threshold Ith. That is, the abnormality determination circuit 34 determines whether the current between the transparent electrodes 11 and 12 during the determination period is equal to or greater than the overcurrent determination threshold Ith. Then, the abnormality determination circuit 34 determines that the detection of a current equal to or higher than the overcurrent determination threshold value Ith is abnormal.

The abnormality determination circuit 34 transmits determination data indicating that the light control device is abnormal to the timing control circuit 26 and the abnormality notification means 35. For example, the abnormality determination circuit 34 includes an A/D converter and converts an analog signal, which is the sample signal Is, into determination data of a digital signal.

According to this configuration, the current detection circuit 31 detects the current between the transparent electrodes 11 and 12 including the non-target period, and the current detection mask circuit 32 detects the detection signal of the non-target period with respect to the detection signal Ia. An extracted signal Im corresponding to the detection signal Ia with Ia masked is output. The peak hold circuit 33 holds the maximum value among the extracted signals Im, and outputs the held maximum value as a sample signal Is. This has the effect that the abnormality in the light control device can be detected even if the abnormality in the light control device occurs over the non-target period.

The abnormality determination circuit 34 compares this sample signal Is with an overcurrent determination threshold Ith, and determines that it is abnormal if a sample signal Is equal to or greater than the overcurrent determination threshold Ith is detected.

According to this configuration, the maximum value of the current extraction signal Im detected during the determination target period is held in the peak hold circuit as the sample signal Is. Therefore, compared to a configuration in which the determination as to whether the detection signal is equal to or greater than the overcurrent determination threshold Ith is performed sequentially in the order of detection, the number of determinations can be reduced.

For example, in a configuration that converts an analog signal that is the detection signal Ia into a digital signal for determination, it takes time to A/D convert the detection signal Ia. In the configuration in which the comparison between the detection signal Ia and the overcurrent determination threshold Ith is performed sequentially in the order of detection, time is required for A/D conversion when determining each detection signal Ia. As a result, the determination is performed at a cycle longer than the time required for A/D conversion, and the maximum value of the detection signal Ia may be excluded from the determination. In this regard, if the maximum value of the detection signal Ia is held as the sample signal Is, one A/D conversion is sufficient for all the detection signals Ia detected during the determination period, so the detection signal Ia It is possible to prevent the maximum value of from being excluded from the determination target.

(If the dimmer is normal)
The timing control circuit 26 continues to apply the driving voltage between the first transparent electrode 11 and the second transparent electrode 12 when the judgment result that the light control device is normal is input from the abnormality judgment circuit 34. .

(If the light control device is abnormal)
On the other hand, when the timing control circuit 26 receives the judgment result that the light control device is abnormal from the abnormality judgment circuit 34, the timing control circuit 26 turns off all the switches Q1, Q2, Q3, and Q4 to turn off the first switch. The application of the driving voltage between the transparent electrode 11 and the second transparent electrode 12 is stopped. This has the effect of suppressing an increase in power consumption due to an abnormality in the light control device.

(Abnormality notification means 35 of abnormality detection means 30)
When a determination result indicating that the light control device is abnormal is inputted, the abnormality notification means 35 outputs a message to the effect that the light control device is abnormal.

[Effect]
The abnormality detection method performed by the abnormality detection means 30 will be explained using the transition of the mask signal SIGM, the reset signal SIGR, the detection signal Ia, the extraction signal Im, and the sample signal Is.

Note that FIG. 3A shows changes in the mask signal SIGM output by the timing control circuit 26, the voltage level V11 of the first transparent electrode 11, the voltage level V12 of the second transparent electrode 12, and the reset signal SIGR. FIG. 3B shows a change in the normal current flowing between the transparent electrodes 11 and 12 and the sample signal Is of the peak hold circuit 33. FIG. 3C shows the changes in the normal current flowing between the transparent electrodes 11 and 12, the abnormal overcurrent, and the sample signal Is of the peak hold circuit 33.

As shown in FIG. 3, first, the timing control circuit 26 waits with all switches Q1, Q2, Q3, and Q4 turned off. That is, the timing control circuit 26 waits for each transparent electrode 11, 12 in a floating state.

Next, the timing control circuit 26 raises the mask signal SIGM at timing ta, and causes the current detection mask circuit 32 to start masking. Furthermore, at timing ta, the timing control circuit 26 turns on the second switch Q2 and the third switch Q3, and turns off the first switch Q1 and the fourth switch Q4. Then, the timing control circuit 26 starts applying a voltage pulse such that the first transparent electrode 11 is at the ground level and the second transparent electrode 12 is at the output level of the booster circuit 23.

Next, the timing control circuit 26 raises the reset signal SIGR after the timing ta has elapsed, and resets the peak hold circuit 33. Subsequently, the timing control circuit 26 lowers the reset signal SIGR until timing tb at the end of the non-target period. Further, the timing control circuit 26 lowers the mask signal SIGM raised at timing ta at timing tb after the non-target period has elapsed, and causes the current detection mask circuit 32 to finish masking. Then, the timing control circuit 26 sets timing tb at the end of the non-target period as the start timing of the determination target period.

Here, the timing ta is the application timing at which the application of the voltage pulse between the transparent electrodes 11 and 12 is started. The current between the transparent electrodes 11 and 12 causes a spike immediately after the timing ta. The spike detected by the current detection circuit 31 is greater than or equal to the overcurrent determination threshold Ith.

On the other hand, the period from timing ta to timing tb is a non-target period. The timing control circuit 26 causes the current detection mask circuit 32 to continue masking until timing tb of the non-target period, which is determined by estimating that the spike becomes less than the threshold value. That is, the timing control circuit 26 causes the current detection mask circuit 32 to perform masking from timing ta when a spike occurs to timing tb. Further, the peak hold circuit 33 is also reset by raising the reset signal SIGR between timing ta and timing tb when a spike occurs.

As a result, the current detection mask circuit 32 outputs an extraction signal Im indicating that the current between the transparent electrodes 11 and 12 is less than the overcurrent determination threshold Ith from timing ta to timing tb. Furthermore, from the timing reset by the reset signal SIGR after the timing ta to the timing tb, the peak hold circuit 33 keeps the sample signal Is, which has the maximum value less than the overcurrent determination threshold Ith, at the GND level value. Output with . Thereby, the abnormality determination circuit 34 determines that the current between the transparent electrodes 11 and 12 is less than the overcurrent determination threshold Ith from timing ta to timing tb, and determines that the light control device is normal. do.

Further, the timing control circuit 26 turns on the second switch Q2 and the third switch Q3 and turns off the first switch Q1 and the fourth switch Q4 from timing ta. Then, the timing control circuit 26 continues to apply a voltage pulse such that the first transparent electrode 11 is at the ground level and the second transparent electrode 12 is at the output level of the booster circuit 23.

Next, the timing control circuit 26 turns off all the switches Q1, Q2, Q3, and Q4 at timing tc after timing tb, and puts each transparent electrode 11 and 12 in a floating state. Then, the timing control circuit 26 sets the next timing ta after the timing tc as the timing at which the determination target period ends. The timing control circuit 26 waits with all switches Q1, Q2, Q3, and Q4 turned off from timing tc to timing ta. The period to be determined is the period from timing tb to the next timing ta.

Further, the timing control circuit 26 continues to lower the reset signal SIGR until timing ta, continues to update the maximum value of the extraction signal Im, and continues to update the maximum value held by the peak hold circuit 33. Then, after the timing ta has elapsed, the timing control circuit 26 raises the reset signal SIGR to reset the peak hold circuit 33. Further, the timing control circuit 26 raises the mask signal SIGM at timing ta to cause the current detection mask circuit 32 to start masking, and lowers the mask signal SIGM at timing tb to cause the current detection mask circuit 32 to stop masking. let

(Normal)
Here, as shown in FIG. 3B, when a normal current is flowing between the transparent electrodes 11 and 12, the extraction signal Im output by the current detection mask circuit 32 is less than the overcurrent determination threshold Ith. The peak hold circuit 33 outputs a sample signal Is having a maximum value less than the overcurrent determination threshold Ith. When a normal current flows between the transparent electrodes 11 and 12, the sample signal Is does not change from the lowest value because the extracted signal Im is less than the overcurrent determination threshold Ith. The abnormality determination circuit 34 determines that the current between the transparent electrodes 11 and 12 is less than the overcurrent determination threshold Ith based on the value of the sample signal Is that does not change from the lowest value, and determines that the light control device is normal. do.

(at the time of abnormality)
On the other hand, as shown in FIG. 3(c), when an abnormal overcurrent is flowing between the transparent electrodes 11 and 12, the extraction signal Im output from the current detection mask circuit 32 is equal to or higher than the overcurrent determination threshold Ith. become. In that case, the peak hold circuit 33 outputs a sample signal Is having a maximum value greater than or equal to the overcurrent determination threshold Ith. The abnormality determination circuit 34 determines that a current equal to or greater than the overcurrent determination threshold Ith has flowed between the transparent electrodes 11 and 12 based on the value of the sample signal Is having a maximum value equal to or higher than the overcurrent determination threshold Ith, and performs dimming. It is determined that the device is abnormal.

Then, the abnormality notification means 35 receives the input of the result of determining that the light control device is abnormal, and outputs a message to the effect that the light control device is abnormal. Furthermore, the timing control circuit 26 turns off all the switches Q1, Q2, Q3, and Q4 at timing tc after timing tb. As a result, the first transparent electrode 11 and the second transparent electrode 12 are separated from the timing control circuit 26, and the application of the driving voltage between the first transparent electrode 11 and the second transparent electrode 12 continues to be stopped.

As described above, according to the above embodiment, the following effects can be obtained.
(1) Each time a voltage pulse is applied between the transparent electrodes 11 and 12, the timing control circuit 26 sets a determination target period. Since the presence or absence of an abnormality in the light control device is determined based on the application period of the voltage pulse, if an abnormality occurs in the light control device, the occurrence of the abnormality is immediately detected.

(2) The current spike that occurs at timing ta is excluded from the determination by the abnormality determination circuit 34. As a result, erroneous determinations caused by spikes are suppressed, and the accuracy of detecting abnormalities occurring in the light control device can be improved.

(3) A single common timing control circuit 26 controls timing ta when a spike starts to occur and timing tb when detecting something other than spikes. Therefore, it is possible to improve the accuracy of excluding current spikes caused by the application of voltage pulses from the determination target.

(4) The current detection circuit 31 detects the current between the transparent electrodes 11 and 12 including the non-target period, and the current detection mask circuit 32 masks the detection signal Ia of the non-target period from the detection signal Ia. do. As a result, the abnormality in the light control device can be detected even when the abnormality in the light control device occurs over the non-target period.

(5) The maximum value of the current detected during the determination target period is held in the peak hold circuit 33. Therefore, compared to a configuration in which the determination as to whether the extracted signal Im is equal to or greater than the threshold value is performed sequentially in the order of detection, the number of determinations can be reduced.

(6) In particular, in the abnormality determination circuit 34 that converts the extraction signal Im, which is an analog signal, into determination data of a digital signal, it takes time to A/D convert the extraction signal Im.

In a configuration in which the extraction signal Im and the overcurrent determination threshold Ith are sequentially executed in the order of detection as in the conventional technology, time is required for A/D conversion when determining the extraction signal Im. Then, the determination may be performed at a cycle longer than the time required for A/D conversion, and the maximum value of the extracted signal Im may be excluded from the determination.

In this embodiment, since the peak hold circuit 33 holds the maximum value of the extraction signal Im, one A/D conversion is sufficient for all the extraction signals Im detected during the determination target period. Therefore, according to this embodiment, there is an effect that the maximum value of the extracted signal Im will not be excluded from the determination target.

(7) In this embodiment, when the abnormality determination circuit 34 determines that the light control device is abnormal, the timing control circuit 26 stops applying the drive voltage. Therefore, it is possible to prevent an increase in power consumption due to an abnormality in the light control device.

(8) Even if the direction of current flow is reversed between the transparent electrodes 11 and 12, the direction of current flow detected by the current detection circuit 31 remains constant. Therefore, a simple configuration that detects a current flowing in one direction can be adopted as the current detection circuit 31.

(9) A fuse with a large blowing current is difficult to immediately disconnect the constant voltage power source 21 and the booster circuit 23 when the constant voltage power source 21 outputs an overcurrent. On the other hand, with the above-described configuration, application of the drive voltage is stopped when it is determined that the light control device is abnormal. That is, various circuits for driving the light control device are protected against abnormalities in the light control device itself by the control performed by the timing control circuit 26. Various circuits for driving the light control device are appropriately protected against abnormalities in other circuits by an overcurrent protection circuit 22 that includes a fuse with a large blowing current.

(10) It is reported to the outside that an abnormality has occurred in the light control device. Therefore, it is possible to determine whether an abnormality that is visible from the outside is caused by an abnormality occurring in the circuit for driving the light control device or an abnormality occurring in the light control device itself. As a result, it becomes easier to deal with abnormalities related to the light control device.

In this manner, in this embodiment, the abnormality detection means 30 detects an abnormality in the light control device by detecting an overcurrent due to a short circuit in a circuit, a ground fault, or the like.

Note that this embodiment can be modified as follows.
(Modification 1)
As a first modification, the timing control circuit 26 can set the timing ta at which the mask signal SIGM rises to a predetermined time earlier than the voltage pulse application timing. At this time, the non-target period is a period from a predetermined time before the voltage pulse application timing to the timing tb at which the mask signal SIGM falls. According to this configuration, the current detection mask circuit 32 masks the detection signal Ia before a current spike occurs due to the application of the voltage pulse. Therefore, it becomes possible to further suppress erroneous determinations caused by spikes.

(Modification 2)
As a second modification, the timing control circuit 26 can change the timing at which the reset signal SIGR rises to the timing at which the mask signal SIGM rises or the timing at which a voltage pulse is applied. Furthermore, the timing control circuit 26 can change the timing at which the reset signal SIGR falls to the timing at which the mask signal SIGM falls.

(Modification 3)
As a third modification, the light control device includes a separate full-bridge control section for driving each switch Q1, Q2, Q3, and Q4 of the drive voltage generation circuit 27, and the timing control circuit 26 includes a current detection mask circuit and , the configuration can be changed to a configuration specialized for driving the peak hold circuit 33. At this time, the timing control circuit 26 determines the start timing of the non-target period and the end timing of the non-target period based on the timing at which the full bridge control unit outputs the control signal. The full bridge control section stops applying the drive voltage upon receiving the result that the light control device is determined to be abnormal.

(Modification 4)
As a fourth modification, the abnormality detection means 30 is configured such that the current detection mask circuit 32, the peak hold circuit 33, and the abnormality determination circuit 34 are omitted, and the abnormality detection means 30 is stored in the A/D converter, the central processing unit, and the memory. An abnormality determination means is configured in which the abnormality detection program is responsible for the functions of those circuits, and can be changed to one that performs various processes using software.

That is, the A/D converter converts the detection signal Ia of the current detection circuit 31 into digital data and transmits it to the abnormality determination means. In addition, the abnormality detection program includes a predetermined non-target period until the current spike between the transparent electrodes 11 and 12 that occurs at the timing of voltage pulse application becomes less than the overcurrent determination threshold Ith, and a non-target period other than the non-target period. Differentiate the period covered by the judgment.

Then, the abnormality determination means that has received the digital data of the detection signal Ia excludes data in the non-target period from the digital data of the detection signal Ia, and Mask processing is performed to process only the digital data. Furthermore, peak hold processing is performed to extract and store the maximum value of the digital data of the detection signal Ia during the determination target period. Then, the maximum value is compared with the overcurrent determination threshold value Ith stored as digital data, and when the maximum value is equal to or greater than the overcurrent determination threshold value Ith, abnormality determination processing is performed.

(Modification 5)
As a fifth modification, the timing control circuit 26 may control the detection timing of the current detection circuit 31 so that the current detection circuit 31 detects the current only during the determination target period. On this occasion,
The abnormality detection means 30 can omit the current detection mask circuit 32.

<Second embodiment>
A second embodiment of the present invention will be described below with reference to FIGS. 4 to 7. The second embodiment differs from the first embodiment in that it includes an earth leakage abnormality detection means 40 in addition to the abnormality detection means 30.

As shown in FIG. 4, the leakage abnormality detection means 40 includes a source current detection circuit 41 that detects the source current I1 of the drive voltage generation circuit 27 that drives the light control film 10, and a sink current detection circuit 42 that detects the sink current I2. It has two current detection circuits, including a difference detection circuit 43 that detects the difference between the detected source current I1 and sink current I2, and an earth leakage determination circuit 44 that determines earth leakage based on the magnitude of the difference.

Furthermore, in the second embodiment, a leakage current is detected using a spike-like current during a non-target period in which the current detection mask circuit 32 masks the influence of the spike-like current in the first embodiment.

Specifically, as shown in FIG. 5, the drive voltage generation circuit 27 switches the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 to each other in the same manner as in the first embodiment. Voltage pulses of different polarities are alternately repeated and applied between the first transparent electrode 11 and the second transparent electrode 12 of the light control film 10.

In the second embodiment, when the voltage pulse rises or falls, the source current I1 and the sink current I2 of the spike-like current caused by the capacitance between the transparent electrodes 11 and 12 are detected, and the spike-like current I1 and sink current I2 are detected. Detect the difference between

(source current I1)
The output terminal of the booster circuit 23 is connected to the power supply side terminal of the drive voltage generation circuit 27 via the source current detection circuit 41. Thereby, the source current detection circuit 41 detects the source current I1 flowing into the power supply side terminal of the drive voltage generation circuit 27.

(sink current I2)
The ground level side terminal of the drive voltage generation circuit 27 is connected to the ground level via the sink current detection circuit 42. As a result, the sink current detection circuit 42 detects the sink current I2 flowing out from the ground level side terminal of the drive voltage generation circuit 27.

(Earth leakage abnormality detection means 40)
FIG. 4, FIG. 5, and FIG. 6 show the configuration of the earth leakage abnormality detection means 40 of this embodiment. The earth leakage abnormality detection means 40 includes a source current detection circuit 41 and a sink current detection circuit 42, a difference detection circuit 43 that detects the difference between the source current I1 and the sink current I2, and a difference detection circuit 43 that detects the difference between the source current I1 and the sink current I2, and uses the value of the detected difference as a threshold value. It has an earth leakage determination circuit 44 for comparison.

The earth leakage abnormality detection means 40 includes a source current detection circuit 41 of the earth leakage abnormality detection means 40 installed upstream of the first switch Q1 and the second switch Q2 of the drive voltage generation circuit 27, and the source current detection circuit 41 of the earth leakage abnormality detection means 40. A sink current detection circuit 42 of the earth leakage abnormality detection means 40 is installed on the downstream side of the circuit.

(Operating principle of earth leakage abnormality detection means 40)
The operating principle of the earth leakage abnormality detection means 40 of this embodiment will be explained below.

Even if the drive voltage generation circuit 27 alternately switches the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 to alternately change the direction of the current flowing to the light control film 10, the source current does not change. The direction of the source current I1 flowing to the detection circuit 41 and the sink current I2 flowing to the sink current detection circuit 42 are the same, and it is possible to measure a current whose direction does not change.

The timing control circuit 26 controls the output timing of the drive voltage generation circuit 27 and applies a drive voltage between the first transparent electrode 11 and the second transparent electrode 12.

(First driving state)
The timing control circuit 26 turns on the first switch Q1 and the fourth switch Q4, and turns off the second switch Q2 and the third switch Q3, so that the second transparent electrode 12 is connected to the booster circuit 23. A voltage pulse is applied between the transparent electrodes 11 and 12 so that the output level becomes , and the first transparent electrode 11 becomes the ground level.

At this time, the source current I1 flows into the light control film 10 via the terminal 2 of the drive voltage generation circuit 27 connected to the second transparent electrode 12 of the light control film 10. Then, the sink current I2 flows out from the light control film 10 via the terminal 1 of the drive voltage generation circuit 27 connected to the first transparent electrode 11 of the light control film 10.

(Second driving state)
Further, the timing control circuit 26 turns off the first switch Q1 and the fourth switch Q4, and turns on the second switch Q2 and the third switch Q3, whereby the first transparent electrode 11 is boosted. A voltage pulse is applied between the transparent electrodes 11 and 12 so that the output level of the circuit 23 becomes the same and the second transparent electrode 12 becomes the ground level.

At this time, the source current I1 flows into the light control film 10 via the terminal 1 of the drive voltage generation circuit 27 connected to the first transparent electrode 11 of the light control film 10. Then, a sink current I2 flows out from the light control film 10 via the terminal 2 of the drive voltage generation circuit 27 connected to the second transparent electrode 12 of the light control film 10.

Here, when the polarity of the voltage pulse applied between the transparent electrodes 11 and 12 is changed, the direction in which the current flows between the transparent electrodes 11 and 12 is also reversed. In this regard, the currents detected by the source current detection circuit 41 and the sink current detection circuit 42 change as described above as the polarity of the voltage pulse changes. As a result, even if the direction of current flow is reversed between the transparent electrodes 11 and 12, the direction of current flow detected by the source current detection circuit 41 and the sink current detection circuit 42 remains constant. Therefore, the source current detection circuit 41 and the sink current detection circuit 42 each detect a current flowing in one direction.

(Detection of electric leakage)
When a leakage occurs around the light control film 10, the sink current I2 flowing out of the light control film 10 is smaller than the source current I1 flowing into the light control film 10. The abnormality detection means 30 of this embodiment detects the value of ((source current I1) - (sink current I2)), determines if the value is large, and determines that a leakage has occurred in that case. It is determined that there is a failure.

Below, with reference to FIG. 6, the source current detection circuit 41, the sink current detection circuit 42, and the difference detection circuit 43 that detects the difference between the source current I1 and the sink current I2 of the abnormality detection means 30 of this embodiment. A specific configuration of the earth leakage determination circuit 44 that detects earth leakage by comparing the detected difference value with a threshold value will be explained.

(Source current detection circuit 41)
As shown in FIG. 6, the source current detection circuit 41 detects the source current I1 by amplifying the potential difference generated across the shunt resistor R5 with a differential amplifier circuit configured with the operational amplifier 1.

(Sink current detection circuit 42)
Similarly, the sink current detection circuit 42 detects the sink current I2 by amplifying the potential difference generated across the shunt resistor R10 with a differential amplifier circuit configured with the operational amplifier 2.

(Difference detection circuit 43)
The difference detection circuit 43 uses a differential amplifier circuit configured with the operational amplifier 3 to generate a differential output according to the difference between the source current I1 detected by the source current detection circuit 41 and the sink current I2 detected by the sink current detection circuit 42. Outputs voltage Vd.

(Earth leakage determination circuit 44)
In the earth leakage determination circuit 44, the voltage value corresponding to the difference output voltage Vd between the source current I1 and the sink current I2 detected by the difference detection circuit 43 is determined by the comparison circuit 44a, and the earth leakage value created by the resistor R17, the variable resistor Rv, and the resistor R18 is determined by the comparator circuit 44a. When the differential output voltage Vd exceeds the earth leakage determination threshold voltage Vth by comparison with the determination threshold voltage Vth, a pulse voltage of an earth leakage detection signal is generated at the output terminal of the comparator circuit 44a. Here, this earth leakage determination threshold value Vth can be freely set by making it variable using a variable resistor Rv.

The output terminal of the comparator circuit 44a that generated the pulse voltage of this leakage detection signal is connected to the set terminal (S) of the latch circuit 44b. Thereby, when the pulse voltage of the leakage detection signal is input to the latch circuit 44b even once, the output terminal of the latch circuit 44b outputs the leakage recording signal.

In this way, the latch circuit 44b monitors the pulse voltage of the earth leakage detection signal, and from the time when an earth leakage occurs, outputs the earth leakage record signal to the output terminal of the latch circuit 44b, thereby making it possible to determine whether or not an earth leakage has occurred. .

Note that the latch circuit 44b is reset, for example, when the power is turned on, and is not reset for each reset signal SIGR. Furthermore, when it is desired to perform earth leakage detection in a certain period, the latch circuit 44b is reset each time the period of the period in which earth leakage detection is started is started.

(Operation of earth leakage abnormality detection means 40)
Next, the operation of the earth leakage abnormality detection means 40 of this embodiment will be explained with reference to the waveform diagram of FIG.

There is a capacitance between the transparent electrodes 11 and 12 of the light control film 10 to which terminals 1 and 2 of the drive voltage generation circuit 27 are connected. Therefore, when switching the drive voltage Vdc applied to terminals 1 and 2 of the drive voltage generation circuit 27 to a positive voltage and when switching to a negative voltage, the output of the source current detection circuit 41 = source current I1 and the output of the sink current detection circuit 42 = the sink current I2 has a spike-like current waveform.

(Normal)
When the circuit is normal, the source current I1 and the sink current I2 have the same current waveform, so the differential output voltage Vd of the differential detection circuit 43 becomes the GND level.

(at the time of abnormality)
On the other hand, if current leaks around the dimmer film 10 and causes a current leakage in the circuit, the dimmer The sink current I2 returning from the transparent electrode 11 or 12 of the film 10 to the drive voltage generation circuit 27 becomes smaller.

When there is such a leakage, the waveform of the differential output voltage Vd output from the differential detection circuit 43 becomes spike-like. The difference output voltage Vd of the difference detection circuit 43 is compared with the earth leakage determination threshold Vth by the comparison circuit 44a of the earth leakage determination circuit 44. As a result, a pulsed comparison result signal Vp is output as an output of the comparison circuit 44a.

The latch circuit 44b of the leakage determination circuit 44 continues to output the comparison result signal Vp output by the pulsed comparison circuit 44a as the leakage recording signal Vmem until SIGR is reset. By monitoring this earth leakage recording signal Vmem, it can be determined whether or not an earth leakage has occurred.

(Modification 6)
As a sixth modification of the second embodiment, similar to the fourth modification of the first embodiment, the abnormality detection means 30 includes an A/D converter, a central processing unit, and an abnormality detection device stored in a memory. It is possible to configure the abnormality determination means by a program and to perform processing by having software take charge of various circuit functions.

That is, the A/D converter converts the source current I1 output from the source current detection circuit 41 into digital data and transmits the digital data to the abnormality determining means. Further, the A/D converter converts the sink current I2 output from the sink current detection circuit 42 into digital data and transmits the digital data to the abnormality determining means.

The abnormality determining means that receives the digital data of the source current I1 and the sink current I2 calculates difference data between the source current I1 and the sink current I2. Then, the abnormality determining means compares the difference data with the threshold data for earth leakage determination, and performs the earth leakage determination process when the difference data exceeds the threshold data for earth leakage determination. In this way, it is possible to have the functions of the difference detection circuit 43 and the leakage determination circuit 44 performed by digital processing by the abnormality determination means configured by the abnormality detection program.

The second embodiment includes the earth leakage abnormality detection means 40 described above and the abnormality detection means 30 described in the first embodiment. Then, the abnormality notification means 35 receives the input of the result of the abnormality detection means 30 determining that there is an abnormality due to overcurrent, and outputs a message to the effect that the dimming device is abnormal due to overcurrent. Further, the abnormality notification means 35 receives the input of the result of determining that the light control device is leaking electricity by the earth leakage abnormality detection means 40, and outputs a message to the effect that the light control device is leaking electricity. In this manner, the abnormality notification means 35 distinguishes and notifies the abnormality determination due to abnormal overcurrent and the leakage determination due to the earth leakage abnormality detection means 40.

Technical ideas derived from the above embodiments and modified examples are additionally described below.
[Additional notes]
An abnormality detection means 30 used in a light control device,
The light control device includes:
comprising a light control layer located between transparent electrodes, and changing the transmittance of the light control layer by applying a driving voltage that alternately repeats voltage pulses of mutually different polarities between the transparent electrodes;
a booster circuit that converts the voltage level of the constant voltage power supply to the voltage level of the voltage pulse;
further comprising a drive voltage generation circuit 27 that generates the drive voltage from the output level of the booster circuit,
The drive voltage generation circuit 27 includes a full bridge circuit including a first switch, a second switch, a third switch, and a fourth switch, and the first switch and the third switch are connected in series. the second switch and the fourth switch are connected in parallel,
A connecting portion between the first switch and the second switch is connected to the booster circuit,
A connection portion between the third switch and the fourth switch is connected to a ground level via the detection circuit,
One of the transparent electrodes is connected to a connecting portion between the first switch and the third switch,
The other transparent electrode is connected to a connecting portion between the second switch and the fourth switch,
The light control device includes:
turning on the first switch and the fourth switch and turning off the second switch and the third switch; turning off the first switch and the fourth switch; and , further comprising a timing control unit that applies the driving voltage between the transparent electrodes by alternately repeating turning on the second switch and the third switch,
The abnormality detection means 30 includes:
comprising an abnormality determining means for determining whether the current between the transparent electrodes is equal to or higher than a threshold for overcurrent determination, and determining that it is abnormal if a current equal to or higher than the threshold for overcurrent determination is detected;
The abnormality determining means includes a detection circuit that detects a current between the transparent electrodes,
The detection circuit detects a current flowing between the third switch and the fourth switch to a ground level as a current between the transparent electrodes.
Abnormality detection means 30.

According to the configuration described in the above supplementary note, the connection portion between the first switch and the third switch is connected to one transparent electrode. A connecting portion between the second switch and the fourth switch is connected to the other transparent electrode. Then, the connection destination of the connection portion between the third switch and the fourth switch is switched between one transparent electrode and the other transparent electrode. That is, the path through which the current detected by the detection circuit flows is switched between a path connecting one transparent electrode and the ground level and a path connecting the other transparent electrode and the ground level.

Here, when the polarity of the voltage pulse applied between the transparent electrodes changes, the direction in which the current flows between the transparent electrodes also reverses. In this regard, with the configuration described in the appendix above, the object detected by the detection circuit changes as described above in accordance with the change in the polarity of the voltage pulse. As a result, even if the direction of current flow is reversed between the transparent electrodes, the direction of current flow detected by the detection circuit remains constant. Further, since a simple configuration for detecting a current flowing in one direction can be adopted as the detection circuit, the configuration of the abnormality detection means 30 can be simplified.

Further, an earth leakage abnormality detection means 40 used in a light control device,
Comprising a source current detection circuit 41 and a sink current detection circuit 42,
An earth leakage determination circuit that includes a difference detection circuit 43 that compares the source current I1 detected by the source current detection circuit 41 and the sink current I2 detected by the sink current detection circuit 42, and determines whether there is a leakage based on the output of the difference detection circuit 43. An earth leakage abnormality detection means 40 comprising 44.

Further, the earth leakage determination circuit 44 includes a circuit that can freely set the earth leakage determination threshold value for determining the existence of earth leakage by making it variable using a resistor R17, a variable resistor Rv, and a resistor R18.

Further, the abnormality notification means 35 distinguishes and notifies abnormality determination due to overcurrent by the abnormality detection means 30 and leakage determination by the earth leakage abnormality detection means 40.

Ia...Detection signal Ith...Threshold value for overcurrent determination I1...Source current I2...Sink current R1 to R18...Resistance Rv...Variable resistance SIGM...Mask signal SIGR... Reset signal Q1...First switch Q2...Second switch Q3...Third switch Q4...Fourth switch V11...Voltage level of first transparent electrode V12...Voltage level of second transparent electrode Voltage level Vd...Differential output voltage Vmem...Earth leakage recording signal Vp...Comparison result signal Vth...Earth leakage determination threshold 10...Dimmer film 11...First transparent electrode 12... Second transparent electrode 13...Dimmer layer 20...Drive circuit 21...Constant voltage power supply 22...Overcurrent protection circuit 23...Boost circuit 24...Control power supply circuit 25... Input means 26...timing control circuit 27...drive voltage generation circuit 30...abnormality detection means 31...current detection circuit 32...current detection mask circuit 33...peak hold circuit 34... Abnormality determination circuit 35...Abnormality notification means 40...Earth leakage abnormality detection means 41...Source current detection circuit 42...Sink current detection circuit 43...Difference detection circuit 44...Earth leakage determination circuit

Claims (13)

An abnormality detection means used in a light control device,
The light control device includes a light control layer located between transparent electrodes, and has a drive voltage generation circuit that applies a drive voltage between the transparent electrodes that alternately repeats voltage pulses of mutually different polarities,
The abnormality detection means includes:
an abnormality determining means that determines whether the current between the transparent electrodes during the determination target period is equal to or higher than a threshold for overcurrent determination, and determines that detection of a current equal to or higher than the threshold for overcurrent determination is abnormal; ,
A predetermined period until a spike of current between the transparent electrodes that occurs at the timing of applying the voltage pulse becomes less than the overcurrent determination threshold is a non-target period, and the non-target period is from the timing of applying the voltage pulse to a timing control unit that sets the start timing of the determination target period to the time when the determination target period has elapsed;
Equipped with
Furthermore, it is equipped with an earth leakage abnormality detection means,
The earth leakage abnormality detection means
a source current detection circuit that detects a source current flowing into a power supply side terminal of the drive voltage generation circuit;
a sink current detection circuit that detects a sink current flowing out from a ground level side terminal of the drive voltage generation circuit;
a difference detection circuit that detects a difference between the source current and the sink current in the non-target period;
It has an earth leakage judgment circuit that detects earth leakage by comparing the detected difference value with the earth leakage judgment threshold value.
An abnormality detection means characterized by: The abnormality detection means according to claim 1, wherein the timing control section controls the application timing of the voltage pulse. The abnormality detection means according to claim 1 or 2,
The abnormality determining means includes:
a current detection circuit that detects the current between the transparent electrodes;
a current detection mask circuit that partially masks the detection signal of the current detection circuit;
determining whether a masked detection signal by the current detection mask circuit is equal to or greater than the overcurrent determination threshold, and determining that detection of a current equal to or greater than the overcurrent determination threshold is abnormal; comprising a circuit;
The timing control section includes:
An abnormality detection means, characterized in that a period masked by the current detection mask circuit is the non-target period. The abnormality detection means according to claim 3,
The abnormality determination means further includes a peak hold circuit that holds the maximum value of the detection signal during the determination target period,
The determination circuit determines whether the maximum value held by the peak hold circuit is equal to or greater than the overcurrent determination threshold, and determines that the detection of the maximum value equal to or greater than the overcurrent determination threshold is abnormal. It is determined that there is
The abnormality detection means, wherein the timing control section resets the peak hold circuit immediately before the application timing. The abnormality detection means according to any one of claims 1 to 4,
The light control device includes a booster circuit that converts a voltage level of a constant voltage power supply to a voltage level of the voltage pulse, and a drive voltage generation circuit that generates the drive voltage from the output level of the booster circuit,
The timing control unit controls the output timing of the drive voltage generation circuit to apply the drive voltage between the transparent electrodes, and stops application of the drive voltage when it is determined that the abnormality occurs. An abnormality detection means characterized by: The abnormality detection means according to claim 5,
The abnormality determining means includes a current detection circuit that detects a current between the transparent electrodes,
The drive voltage generation circuit includes a full bridge circuit including a first switch, a second switch, a third switch, and a fourth switch, the first switch and the third switch connected in series, and the full bridge circuit connected in series with the first switch and the third switch. a second switch and the fourth switch are connected in parallel;
A connecting portion between the first switch and the second switch is connected to an output level of the booster circuit,
A connection portion between the third switch and the fourth switch is connected to a ground level via the current detection circuit,
A connecting portion between the first switch and the third switch is connected to one of the transparent electrodes,
A connecting portion between the second switch and the fourth switch is connected to the other transparent electrode,
The timing control section is configured to turn on the first switch and the fourth switch, turn off the second switch and the third switch, and turn on the first switch and the fourth switch. applying the driving voltage between the transparent electrodes by alternately repeating turning off the switch and turning on the second switch and the third switch;
The abnormality detecting means is characterized in that the current detection circuit detects a current flowing from a connecting portion between the third switch and the fourth switch to a ground level as the current between the transparent electrodes. The abnormality detection means according to claim 5 or 6,
The abnormality detection means further comprises an overcurrent protection circuit that blows out a fuse to disconnect the booster circuit from the constant voltage power source when the output current of the constant voltage power source is equal to or higher than a predetermined value. The abnormality detection means according to any one of claims 1 to 7,
The abnormality detection means further comprises an abnormality notification means for notifying an external party that an abnormality has occurred in the light control device when the abnormality is determined. The abnormality detection means according to claim 1 ,
An abnormality detection means, comprising a circuit that allows the threshold value for earth leakage determination to be made variable and freely set. The abnormality detection means according to claim 1 or 9 ,
An abnormality detection means, comprising an abnormality notification means that distinguishes and notifies an abnormality determination due to an abnormal overcurrent and an earth leakage determination made by the earth leakage abnormality detection means. An abnormality detection method for detecting an abnormality occurring in a light control device, the method comprising:
The light control device includes a light control layer located between transparent electrodes, and a drive voltage generation circuit applies a drive voltage between the transparent electrodes that alternately repeats voltage pulses of different polarities,
When a non-target period has elapsed, which is a predetermined period from the application timing of the voltage pulse until the spike of current between the transparent electrodes that occurs at the application timing becomes less than the threshold for overcurrent determination, determine whether the current is equal to or greater than the overcurrent determination threshold, and determine that the detection of a current equal to or greater than the overcurrent determination threshold is abnormal ;
The earth leakage abnormality detection means is
detecting a source current flowing into a power supply side terminal of the drive voltage generation circuit;
detecting a sink current flowing from a ground level side terminal of the drive voltage generation circuit;
A leakage abnormality is determined by comparing a detected difference between the source current and the sink current during the non-target period with a threshold for determining leakage.
An anomaly detection method characterized by: An abnormality detection program that causes an abnormality detection means to detect an abnormality that occurs in a light control device,
The light control device includes a light control layer located between transparent electrodes,
a program that controls timing for applying a drive voltage to a drive voltage generation circuit that alternately repeats voltage pulses of mutually different polarities between the transparent electrodes;
When a non-target period has elapsed, which is a predetermined period from the application timing of the voltage pulse until the spike of current between the transparent electrodes that occurs at the application timing becomes less than the threshold for overcurrent determination, a program that controls timing as a start timing of a determination target period for determining whether or not the current is equal to or higher than the overcurrent determination threshold;
The abnormality detection means determines whether or not the current between the transparent electrodes during the determination target period is equal to or higher than an overcurrent determination threshold, and detects that a current equal to or higher than the overcurrent determination threshold is detected as abnormal. and a program that determines that
The abnormality detection means
A circuit that detects a source current flowing into a power supply side terminal of the drive voltage generation circuit with a source current detection circuit and converts it into digital data with an A/D converter,
a circuit for detecting a sink current flowing out from a terminal on the ground level side of the drive voltage generation circuit with a sink current detection circuit and converting it into digital data with an A/D converter;
a program that calculates difference data between the digital data of the source current and the digital data of the sink current in the non-target period;
a program that compares the difference data with threshold data for earth leakage determination, and performs an earth leakage determination process when the difference data exceeds the threshold data for earth leakage determination.
An anomaly detection program characterized by: The abnormality detection program according to claim 12 ,
The abnormality detection means has a circuit that detects the current between the transparent electrodes with a current detection circuit and converts it into digital data with an A/D converter,
A program that distinguishes between a predetermined non-target period and a determination target period other than the non-target period until a current spike between the transparent electrodes that occurs at the timing of applying the voltage pulse becomes less than the overcurrent determination threshold; ,
A program that performs mask processing to process only the digital data of the current in the determination target period from the digital data of the current between the transparent electrodes;
a program that performs peak hold processing that extracts and stores the maximum value of digital current data during the determination target period;
An abnormality detection program comprising: a program that compares the maximum value with an overcurrent determination threshold and performs an abnormality determination process when the maximum value is equal to or greater than the overcurrent determination threshold.

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