JPH1195266A - Driving circuit for electro-chemical dimmer element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving circuit for an electrochemical dimmer element automatically making a current flow through an electrochemical dimmer element for controlling a transmittance of light. SOLUTION: A driving circuit for an electrochemical dimmer element(EC element) comprises am H-bridge type switch circuit 12 in which an EC element for controlling a transmittance of light is connected across the H-bridge part, a constant current circuit 13 for absorbing a constant current connected with this circuit, and a micro computer 14 outputting signals for switching ON-OFF the circuits 12, 13. Moreover, the micro computer 14 outputs a 1st signal for opening the circuits 12, 13 for a specified time to make a current flow through the EC element 4 to reduce a transmittance of light, and a 2nd signal for opening the circuits 12, 13 for a specified time to make a current flow through the EC element 4 to increase the transmittance of light. Therefore, it is possible to automatically make a current flow through the EC element 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit for an electrochemical light control device for automatically supplying a current to an electrochemical light control device for controlling light transmittance.

[0002]

2. Description of the Related Art FIG. 15 is a block diagram showing an apparatus for adjusting the amount of incident light in a conventional image photographing apparatus. This device has a lens 33 that projects the subject 31, and an ND filter 32 is placed in front of the lens 33. The incident light condensed by the lens 33 reaches an ND filter 34 that is detachably configured inside the lens barrel. The ND filter 34 is inserted or retracted as necessary to reduce the transmittance of incident light. N
The light transmitted through the D filter 34 reaches the stop 35. The light that has passed through the stop 35 forms an image on the image sensor 36. The image formed by the image sensor 36 is converted into an electric signal, and an image conversion signal is generated and output from the converted signal. The aperture 35 controls the amount of incident light by controlling the aperture ratio, and controls the amount of light.

FIG. 16A shows a lens 33 shown in FIG.
FIG. 1 is a front view showing an example of an ND filter in front of FIG.
FIG. 6B is a front view illustrating another example of the ND filter in front of the lens 33.

In the ND filter shown in FIG. 16A, a plate-shaped filter 52 having a square planar shape is provided on a guide frame 51.
Is inserted so as to cover the front of the lens 33.

The ND filter shown in FIG. 16B is configured to cover the front of the lens 33 by screwing a screw-in filter 53 having a circular planar shape into the front end of the lens barrel.

FIG. 17 is a front view showing how the ND filter 34 in the lens barrel shown in FIG. 15 is attached and detached. At the tip of the arm 54 as a support member, a filter 34 having a circular planar shape is provided. The filter 34 is supported by an arm 54, and the arm 54 is configured to be movable so that the filter 34 can be inserted into the optical path or retracted from the optical path. Also, the filter 34
Is smaller in size than the filter 32 placed in front of the lens 33.

[0007]

In the conventional apparatus for adjusting the amount of incident light, when a bright subject is photographed in actual photographing, the situation is determined empirically, or the aperture 35 is set to a small aperture. If used in a photographing apparatus having a device for warning that the lens is biased to the side, by following the warning, the ND filter 32 in front of the lens 33 or the ND filter 34 in the lens barrel can be inserted into the optical path. Become. At the time of this insertion, the photographing must be temporarily stopped, and it is considered that photographing cannot be continued substantially continuously. The reason for this is that if the photographing is not stopped, the image photographed when the filters 32 and 34 are inserted is remarkably disturbed, and the sound of mounting the filters 32 and 34 is recorded in the sound.

Further, the necessity of attaching / detaching, inserting / retreating the filters 32 and 34 when photographing a bright subject requires a high-level photographing technique, and the work itself is troublesome.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a driving circuit for an electrochemical dimming element that passes a current to an electrochemical dimming element that controls light transmittance. To provide.

[0010]

In order to solve the above-mentioned problems, a drive circuit for an electrochemical light control device according to the present invention is provided in which an electrochemical light control device for controlling light transmittance is connected to a bridge portion of an H bridge. H-bridge type switch circuit, a constant current circuit connected to the H-bridge type switch circuit for drawing constant current, a timing signal for outputting a signal for opening and closing the H-bridge type switch circuit and the constant current circuit And a generation circuit.

[0011] In the driving circuit of the electrochemical dimming device, H
A bridge type switch circuit, a constant current circuit connected to the circuit, which draws in a constant current, and a timing signal generating circuit for outputting a signal for opening and closing the circuit are provided. Optical element is connected. Therefore, it is possible to automatically supply a current to the electrochemical light control device that controls the light transmittance. Thereby, the electrochemical dimmer can be operated as an ND filter.

In addition, the timing signal generating circuit includes a first circuit for opening the H-bridge type switch circuit and the constant current circuit for a predetermined time so as to supply a current to the electrochemical light control device so as to reduce light transmittance. And a second signal for opening the H-bridge type switch circuit and the constant current circuit for a predetermined time in order to supply a current to the electrochemical light control element so as to increase light transmittance. It is preferred that Thereby, the H-bridge type switch circuit is turned on by the first signal from the timing signal generation circuit, the first constant current is sucked into the constant current circuit, and the electrochemical dimming element is operated in a direction to lower the transmittance. After a certain time, the H-bridge type switch circuit can be turned off. Further, the H-bridge type switch circuit is turned on by the second signal from the timing signal generation circuit, the second constant current is sucked into the constant current circuit, and the electrochemical dimming element is operated in a direction to increase the transmittance, and the constant. After a period of time, the H-bridge type switch circuit can be turned off. In this way, the transmittance of the electrochemical light control device is controlled, and at the same time, when the transmittance of the electrochemical light control device is not changed, the electrochemical light control device is separated from the H-bridge type switch circuit so that unnecessary current flows in or out. Can not be.

When a current is applied to the electrochemical light control device so as to increase the light transmittance, and when the internal resistance of the electrochemical light control device is large, a voltage limiting circuit for changing from a constant current operation to a constant voltage operation is used. Is preferably further included in the H-bridge type switch circuit.

When a current is applied to the electrochemical light control device so as to reduce the light transmittance, and when the internal resistance of the electrochemical light control device is large, a voltage limiting circuit for changing from a constant current operation to a constant voltage operation is used. Is preferably further included in the H-bridge type switch circuit.

It is preferable that the timing signal generating circuit further includes a ROM storing an arbitrary time function waveform of a constant current when decreasing the light transmittance of the electrochemical light control device.

The voltage applied to the H-bridge type switch circuit is applied to the electrochemical light control element when a current is applied to the electrochemical light control element so as to increase the light transmittance or to the electrochemical light control element so as to reduce the light transmittance. It is preferable to further include a circuit for changing the current according to each of the current flows.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an incident light amount adjusting device using a drive circuit of an electrochemical light control device according to first to sixth embodiments of the present invention. FIG. 2A is a front view showing an electrochemical dimmer in the incident light amount adjusting device shown in FIG. 1, and FIG. 2B is a side view of the electrochemical dimmer shown in FIG. 2A. It is.

The apparatus shown in FIG. 1 has a lens 3 into which light from a subject 1 is taken, and the incident light condensed by the lens 3 is applied to an electrochemical dimming element (hereinafter, referred to as an “EC element”) 4. To reach. The light transmitted through the EC element 4 reaches an iris meter (aperture) 5. The iris meter 5 reduces the amount of incident light by controlling the aperture ratio,
It controls the amount of light. The light that has passed through the iris meter 5 forms an image on the image sensor 6. The image sensor 6 converts an image formed into an electric signal. An image conversion signal is output from the image sensor 6.

As shown in FIGS. 2 (a) and 2 (b), a box-like shape is formed by two plate glasses 41 having a quadrangular planar shape facing each other and a frame 42 attached to four sides around the plate glass 41. An enclosed space is created. This sealed space is filled with the electrolyte 43 without any gap. A transparent electrode 44 having a circular planar shape and an annular electrode (counter electrode) 45 located outside the transparent electrode 44 are formed on the inner surface of one of the glass plates 41. This annular electrode 45 is also referred to as a counter electrode because it is electrically opposed to the transparent electrode 44. Lead wires (not shown) for passing a current are drawn out of the EC element 4 from the transparent electrode 44 and the counter electrode 45, respectively.

The EC element 4 switches light transmittance without using a mechanically movable part. A metal, for example, silver, is formed on a transparent electrode 44 driven by a driving circuit shown in FIG. Is reversibly deposited and plated to control the light transmittance to a predetermined value, or the precipitated silver is dissolved to return it to be transparent. This is also called ND-ON (precipitation drive) and ND-OFF (dissolution drive). That is, E
The C element 4 is such that when electric charges are injected from the transparent electrode 44 into the electrolytic solution 43, the transmittance decreases, and when the electric charges are absorbed, the transparent state returns to the original transparent state.

FIG. 3 is a diagram showing a driving circuit of the electrochemical light control device according to the first embodiment of the present invention. This drive circuit comprises an H-bridge type switch circuit 12, a constant current circuit 1
3 and a timing signal generation circuit (hereinafter referred to as “microcomputer”) 14.

The H-bridge type switch circuit 12 has first to
It is composed of fourth transistors T1 to T4 and first to eighth resistors R1 to R8. Also, a constant current circuit 1
Reference numeral 3 includes ninth to eleventh resistors R9 to R11, a capacitor C1, a fifth transistor T5, and an operational amplifier O1. The microcomputer 14 is a circuit that generates a timing signal to the H-bridge type switch circuit 12 and generates a PWM signal to the constant current circuit 13. Also,
Transistors T1 and T3 are of the PNP type, and transistors T2, T4 and T5 are of the NPN type.

The EC element 4 apparently operates like a capacitor, and is thus tentatively shown in FIG. A lead wire A is drawn from a counter electrode of the EC element 4, and a lead wire B is drawn from a transparent electrode of the EC element 4.

The emitters of the transistors T1 and T3 and one ends of the resistors R1 and R5 are connected to a power supply V1. The other end of the resistor R1 is connected to the base of the transistor T1 and one end of the resistor R2.
Is connected to OUT4 of the microcomputer 14. O
When UT4 is LOW, transistor T1 is turned ON and OUT4
Is HIGH and the transistor T1 is turned off. Resistor R
5 is connected to the base of the transistor T3 and one end of the resistor R6, and the other end of the resistor R6 is connected to the microcomputer 1
4 OUT1. When OUT1 is LOW, the transistor T3 is turned on, and when OUT1 is HIGH, the transistor T3 is turned off.

The emitters of the transistors T2 and T4 are both connected to the collector of the transistor T5 of the constant current circuit 3. The collector of the transistor T2 is connected to the collector of the transistor T1 and the lead B of the EC element 4, respectively, and the collector of the transistor T4 is connected to the collector of the transistor T3 and the lead A of the EC element 4, respectively.

One end of each of the resistors R4 and R8 is grounded. The other end of the resistor R4 is connected to the base of the transistor T2 and one end of the resistor R3, respectively, and the other end of the resistor R3 is connected to OUT3 of the microcomputer 14. OUT3 is HIGH and transistor T2 is ON
Then, OUT3 is LOW and the transistor T2 is turned off. The other end of the resistor R8 is connected to the base of the transistor T4 and one end of the resistor R7, respectively.
The other end of 7 is connected to OUT2 of the microcomputer 14.
When OUT2 is HIGH, transistor T4 is turned ON, and OU
When T2 is LOW, the transistor T4 is turned off.

The microcomputer 14 is connected to the power supply V3. OUT5 of the microcomputer 14 is connected to one end of the resistor R9, and the other end of the resistor R9 is connected to the capacitor C1, one end of the resistor R10, and the plus input of the operational amplifier O1. The other end of the resistor R10 is grounded. The output of the operational amplifier O1 is connected to the base of the transistor T5. The negative input of the operational amplifier O1 is connected to the emitter of the transistor T5 and one end of the resistor R11. The other end of the resistor R11 is grounded.

The PWM signal from the microcomputer 14 is OUT5
And divided by a resistor R9 and a resistor R10.
The carrier of the PWM is removed by the capacitor C1 and applied to the positive input of the operational amplifier O1. The microcomputer input IN1 is a voltage indicating the aperture ratio of the diaphragm 5 shown in FIG. The microcomputer 14 recognizes this voltage by the A / D, and outputs the timing signals OUT1 to OUT5 appropriately.

Next, the operation of the drive circuit for the electrochemical light control device shown in FIG. 3 (deposition drive and dissolution drive of the EC device) will be described with reference to FIG. FIG. 4 is a waveform diagram of the drive circuit shown in FIG.

As shown in FIG. 4, first, the transistors T3 and T2 are turned on when the microcomputer outputs OUT1 and OUT3 become LOW and HIGH, respectively. OUT
5 outputs a PWM signal having a constant duty ratio.
The demodulated DC voltage is applied to the positive input of the operational amplifier O1, is replaced by the voltage of the resistor R11, and is converted to a constant current. The current path at this time is the power supply V1
To the transistor T3, and from this T3 to the EC element 4
Flows from the lead A to the lead B of the EC element 4, and from the lead B to the transistor T.
2, from T2 to transistor T5, and from T5 to resistor R11. Thus, the deposition current i1 flows through the EC element 4. Lead A and Lead B
Are as shown by VA-B in FIG.

Next, the microcomputer outputs OUT4 and OUT2
Become LOW and HIGH, respectively, turning on the transistors T1 and T4. OUT5 outputs a PWM signal having a constant duty ratio. The demodulated DC voltage is applied to a positive input of an operational amplifier O1 and a resistor R
11 and is converted into a constant current as a result. At this time, the current path flows from the power supply V1 to the transistor T1, from this T1 to the lead B of the EC element 4, from this lead B to the lead A of the EC element 4, and from this lead A to the transistor T4. From the transistor T4 to the transistor T5, and from the transistor T5 to the resistor R11. Thus, the dissolution current i2 flows through the EC element 4. Therefore, by controlling the current value i1 or i2 and the time for flowing the current, ND-ON,
The time change of the transmittance of the ND-OFF can be controlled.

According to the first embodiment, an H-bridge type switch circuit 1 for connecting a collector or a drain of a transistor to a drive circuit of an EC element is provided.
2, a constant current circuit 13 connected to the circuit 12 for drawing a constant current and a microcomputer 14 for outputting a signal for opening and closing the circuits 12 and 13; 4 and the current set by the constant current circuit 13 is turned on by the switch of the H-bridge.
N / OFF and flowing to the EC element 4 causes deposition or dissolution of metal. Therefore, it is possible to automatically supply a current to the EC element 4 for controlling the light transmittance.
This allows the EC element 4 to operate as an ND filter. That is, it is possible to provide a drive circuit in which the EC element 4 is installed inside the lens block of the imaging device, and the transmittance of the EC element 4 is purely controlled without the intervention of a mechanically movable part.

The transmittance of the EC element 4 can be easily changed by adjusting the amount of charge injected into the EC element 4.

Further, by adjusting the amount and time of the electric charge to be injected into the EC element 4, the time until the EC element 4 reaches the predetermined transmittance can be easily changed or adjusted.

Further, by turning off all the transistors T1 to T4 constituting the H-bridge type switch circuit 12 and putting them in a high impedance state, the metal deposited on the transparent electrode 44 of the EC element 4 can be hardly dissolved. As a result, the transmittance of the EC element 4 can be well maintained at a predetermined value.

Further, since the constant current driving is basically used, it is easy to control the EC element 4 to an accurate transmittance from the relationship between the injected charge amount and the transmittance.

Further, by depositing or dissolving the metal on the transparent electrode 44 of the EC element 4 with a constant current over a period of time during deposition and dissolution, the iris meter 5 also corresponds to the transmittance of the EC element 4. Can react sufficiently. Therefore, even if the transmittance of the EC element 4 is changed, the brightness of the captured image is not disturbed.

FIG. 5 is a diagram showing a driving circuit of an electrochemical light control device according to a second embodiment of the present invention. The same parts as those in FIG. 3 are denoted by the same reference numerals, and only different parts will be described. .

A variable power supply V11 is connected to the emitter of the transistor T1 and one end of the resistor R1. Also,
Power supply V2 is the emitter of transistor T3 and resistor R
5 is connected to one end. An operational amplifier O2 is inserted between the transistor T4 and the resistors R7 and R8. One end of the resistor R7 and one end of the resistor R8 are connected to the positive input of the operational amplifier O2, the output of the operational amplifier O2 is connected to the base of the transistor T4, and the emitter of the transistor T4 is connected to the negative input of the operational amplifier O2. It is connected.

Next, in the operation of the drive circuit of the electrochemical light control device shown in FIG. 5, the operation of the dissolution drive related to the portions different from the drive circuit of FIG. 3 will be described with reference to FIG. FIG. 6 is a waveform diagram of the drive circuit shown in FIG.

As shown in FIG. 6, OUT of the microcomputer output
4 becomes LOW and OUT2 becomes HIGH, turning on the transistor T1. On the other hand, the HIGH level of OUT2 is divided by the resistors R7 and R8, and this divided voltage is applied to the plus input of the operational amplifier O2. The transistor T4 is turned on while the emitter of the transistor T4 is clamped by the applied voltage. At this time, the current path flows from the variable power supply V11 to the transistor T1, flows from the T1 to the lead B of the EC element 4, flows from the lead B to the lead A via the EC element 4, and flows to the lead A. From the transistor T4 to the transistor T5, from the transistor T4 to the transistor T5, and from the transistor T5 to the resistor R11. Thus, the dissolution current i2 flows through the EC element 4. At this time, the maximum voltage applied to the EC element 4 depends on the voltage of the variable power supply V11 and the transistor T clamped by the voltage applied to the plus input of the operational amplifier O2.
4 is the difference voltage from the emitter voltage. This is called the melting limiter voltage. That is, the transistors T1 and T4 which operate during melting out of the transistors constituting the H-bridge type switch circuit 12 are switches with a voltage limiting circuit.

Therefore, when the internal resistance of the EC element 4 is small, the voltage drop of the EC element 4 is smaller than the melting limiter voltage, so that the constant current driving is maintained. EC
As the internal resistance of the element 4 increases, the voltage drop of the EC element 4 also increases. As a result, when the voltage exceeds the melting limiter voltage, the constant current driving cannot be maintained, and the state shifts to the constant voltage driving state by the melting limiter voltage. When the melting is completed, the internal resistance of the EC element 4 increases, so that if the operation is shifted to a constant voltage drive with a limiter at that time, an unnecessary melting current does not need to flow.

Further, the same effects as those of the first embodiment can be obtained in the second embodiment.

FIG. 7 is a diagram showing a driving circuit of an electrochemical light control device according to a third embodiment of the present invention. The same parts as those in FIG. 3 are denoted by the same reference numerals, and only different parts will be described. .

A variable power supply V22 is connected to the emitter of the transistor T3 and one end of the resistor R5. Also,
An operational amplifier O3 is inserted between the transistor T2 and the resistors R3 and R4. One end of the resistor R3 and one end of the resistor R4 are respectively connected to the plus input of the operational amplifier O3, and the output of the operational amplifier O3 is
2 and the emitter of the transistor T2 is connected to the minus input of the operational amplifier O3.

Next, in the operation of the drive circuit of the electrochemical light control device shown in FIG. 7, the operation of the deposition drive related to the different parts from the drive circuit of FIG. 3 will be described with reference to FIG. FIG. 8 is a waveform diagram of the drive circuit shown in FIG.

As shown in FIG. 8, the microcomputer output OUT
When 1 is LOW and OUT3 is HIGH, the transistor T3 is turned ON, while the HIGH level of OUT3 is divided by the resistors R3 and R4, and this divided voltage is applied to the positive input of the operational amplifier O3. The transistor T2 is turned on while the emitter of the transistor T2 is clamped by the applied voltage. At this time, the current path flows from the variable power supply V22 to the transistor T3, flows from the T3 to the lead A of the EC element 4, flows from the lead A to the lead B via the EC element 4, and flows to the lead B. From the transistor T2, from the transistor T2 to the transistor T5, and from the transistor T5 to the resistor R11. Thus, the deposition current i1 flows through the EC element 4. At this time, the maximum voltage applied to the EC element 4 is determined by the voltage of the variable power supply V22 and the transistor T clamped by the voltage applied to the plus input of the operational amplifier O3.
2 is the difference voltage from the emitter voltage. This is called a deposition limiter voltage. That is, the transistors T3 and T2 that operate during deposition among the transistors constituting the H-bridge type switch circuit 12 are switches with a voltage limiting circuit.

Therefore, when the internal resistance of the EC element 4 is small, the voltage drop of the EC element 4 is smaller than the deposition limiter voltage, so that the constant current driving is maintained as it is. EC
As the internal resistance of the element 4 increases, the voltage drop of the EC element 4 also increases. As a result, when the voltage exceeds the deposition limiter voltage, the constant current drive cannot be maintained, and the state shifts to the constant voltage drive state using the deposition limiter voltage. Since the internal resistance of the EC element 4 is large in the initial stage of the deposition, the state of the deposition plating can be made uniform by performing a constant voltage drive with a limiter at that time.

Also, the same effects as those of the first embodiment can be obtained in the third embodiment.

FIG. 9 is a diagram showing a drive circuit for an electrochemical light control device according to a fourth embodiment of the present invention. The same parts as those in FIG. 3 are denoted by the same reference numerals, and only different parts will be described. .

A variable power supply V11 is connected to the emitter of the transistor T1 and one end of the resistor R1. Also,
An operational amplifier O2 is inserted between the transistor T4 and the resistors R7 and R8. One end of the resistor R7 and one end of the resistor R8 are respectively connected to the plus input of the operational amplifier O2, and the output of the operational amplifier O2 is
4 and the emitter of the transistor T4 is connected to the minus input of the operational amplifier O2.

A variable power supply V22 is connected to the emitter of the transistor T3 and one end of the resistor R5. Also,
An operational amplifier O3 is inserted between the transistor T2 and the resistors R3 and R4. One end of the resistor R3 and one end of the resistor R4 are respectively connected to the plus input of the operational amplifier O3, and the output of the operational amplifier O3 is
2 and the emitter of the transistor T2 is connected to the minus input of the operational amplifier O3.

Next, in the operation of the driving circuit of the electrochemical light control device shown in FIG. 9, the operations of the deposition driving and the dissolving driving related to the portions different from the driving circuit of FIG. 3 will be described with reference to FIG. I do. FIG. 10 is a waveform diagram of the drive circuit shown in FIG.

First, the operation of the deposition drive will be described.
As shown in FIG. 10, the microcomputer output OUT1 is
When W and OUT3 become HIGH, the transistor T3 is turned ON. On the other hand, the HIGH level of OUT3 is divided by the resistors R3 and R4, and this divided voltage is applied to the positive input of the operational amplifier O3. The transistor T2 is also turned on while the voltage acts to clamp the emitter of the transistor T2. At this time, the current path flows from the variable power supply V22 to the transistor T3, flows from the T3 to the lead A of the EC element 4, flows from the lead A to the lead B via the EC element 4, and flows to the lead B. From the transistor T2, from the transistor T2 to the transistor T5, and from the transistor T5 to the resistor R11. Thus, the deposition current i1 flows through the EC element 4. At this time, the maximum voltage applied to the EC element 4 is the voltage of the difference between the voltage of the variable power supply V22 and the emitter voltage of the transistor T2 clamped by the voltage applied to the positive input of the operational amplifier O3. This is called a deposition limiter voltage.

When the internal resistance of the EC element 4 is small, the EC
Since the voltage drop of the element 4 is smaller than the limit voltage at the time of deposition, the constant current drive is maintained as it is. As the internal resistance of the EC element 4 increases, the voltage drop of the EC element 4 also increases. As a result, when the voltage exceeds the deposition limiter voltage, the constant current drive cannot be maintained, and the state shifts to the constant voltage drive state using the deposition limiter voltage. Since the internal resistance of the EC element 4 is large in the initial stage of the deposition, the state of the deposition plating can be made uniform by performing a constant voltage drive with a limiter at that time.

Next, the operation of the melting drive will be described.
As shown in FIG.
When W and OUT2 become HIGH, the transistor T1 is turned ON. On the other hand, the HIGH level of OUT2 is divided by the resistors R7 and R8, and the divided voltage is applied to the positive input of the operational amplifier O2. The transistor T4 is also turned on while the voltage acts to clamp the emitter of the transistor T4. At this time, the current path flows from the variable power supply V11 to the transistor T1, flows from the T1 to the lead B of the EC element 4, flows from the lead B to the lead A via the EC element 4, and flows to the lead A. From the transistor T4 to the transistor T5, from the transistor T4 to the transistor T5, and from the transistor T5 to the resistor R11. Thus, the dissolution current i2 flows through the EC element 4. At this time, the maximum voltage applied to the EC element 4 is the voltage of the difference between the voltage of the variable power supply V11 and the emitter voltage of the transistor T4 clamped by the voltage applied to the positive input of the operational amplifier O2. This is called the melting limiter voltage.

If the internal resistance of the EC element 4 is small, the EC
Since the voltage drop of the element 4 is smaller than the melting limiter voltage, the constant current drive is maintained as it is. As the internal resistance of the EC element 4 increases, the voltage drop of the EC element 4 also increases. As a result, when the voltage exceeds the melting limiter voltage, the constant current driving cannot be maintained, and the state shifts to the constant voltage driving state by the melting limiter voltage. When dissolution is complete, E
Since the internal resistance of the C element 4 increases, it is not necessary to supply an unnecessary melting current by switching to a constant voltage drive with a limiter at that time.

The reason why the driving circuit of the electrochemical light control device according to the fourth embodiment is configured as described above is to match the chemical characteristics of the EC device 4 and both the deposition and the melting are performed temporarily. This is because it is used for an EC element suitable for voltage drive.

Also, in the fourth embodiment, the same effects as in the first to third embodiments can be obtained.

FIG. 11 is a diagram showing a drive circuit for an electrochemical light control device according to a fifth embodiment of the present invention. The same parts as those in FIG. 9 are denoted by the same reference numerals, and only different parts will be described. . FIG. 12 is a waveform diagram of the drive circuit shown in FIG.

The microcomputer 14 has a built-in waveform ROM 20. This waveform ROM (Read-Only Memory) 20
Various current waveforms, for example, a current waveform such as a deposition current i1 shown in FIG. 12, are produced by changing the duty ratio of the PWM signal OUT5 of the microcomputer every moment. The waveform ROM 20 can also provide any waveform such as a pulse waveform for performing pulse plating or the like, a linear slope waveform, or an arbitrary curved waveform.

As the data of the ROM 20, the time function waveform of the constant current at the time of deposition is stored as an arbitrary function including an impulse function. The change in the deposition concentration of the EC element 4 can be made smooth or uniform by the time function waveform of the constant current read from the ROM 20.

The microcomputer input IN 2 is a voltage indicating temperature information from a temperature sensor (not shown) installed near the EC element 4. The microcomputer 14 recognizes this voltage by A / D, and thereby, the timing signals OUT1 to OUT
The microcomputer output control is performed so as to output the UT 5 appropriately.

Further, if necessary, it is possible to select a different waveform from the data in the waveform ROM 20 according to the temperature information recognized by the microcomputer 14. Specifically, for example, it is possible to select a waveform that increases smoothly at low temperatures and a waveform that increases in a rectangular or impulse shape at high temperatures.

In the fifth embodiment, the same effects as in the fourth embodiment can be obtained.

FIG. 13 is a diagram showing a driving circuit of the electrochemical light control device according to the sixth embodiment of the present invention.
The same parts as those described above are denoted by the same reference numerals, and only different parts will be described. FIG. 14 is a waveform diagram of the drive circuit shown in FIG.

One end of the resistor R1, the emitter of the transistor T1, the one end of the resistor R5, and the emitter of the transistor T3 are connected to the output of an operational amplifier O4 used as a voltage follower. The D / A OUT signal from the microcomputer 14 is applied to the plus input of the operational amplifier O4.

FIG. 14 is a waveform diagram of the drive circuit shown in FIG. The D / A OUT signal of the microcomputer 14 is shown in FIG.
As shown in FIG. 5, another power supply voltage can be supplied by precipitation and dissolution. In other words, a variable power supply that determines the limiter voltage at the time of deposition and melting is combined into one, and the limiter voltage is changed according to the time of deposition and melting. Thereby, the size of the voltage limiter at the time of deposition and at the time of melting can be arbitrarily changed according to the information on the temperature recognized by the microcomputer 14.

The same effects as in the fifth embodiment can be obtained in the sixth embodiment.

[0070]

As described above, according to the present invention, the H-bridge type switch circuit in which the electrochemical dimming device is connected to the bridge portion of the H-bridge, and the constant current that draws the constant current connected to this circuit. And a timing signal generation circuit that outputs a signal for opening and closing the H-bridge type switch circuit and the constant current circuit. Therefore, it is possible to provide a drive circuit for an electrochemical light control device that automatically supplies a current to the electrochemical light control device that controls light transmittance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an incident light amount adjusting device using a driving circuit of an electrochemical light adjusting device according to first to sixth embodiments of the present invention.

FIG. 2A is a front view showing an electrochemical dimmer in the incident light amount adjusting device shown in FIG. 1;
FIG. 2B is a side view of the electrochemical light control device shown in FIG.

FIG. 3 is a diagram showing a driving circuit of the electrochemical light control device according to the first embodiment of the present invention.

FIG. 4 is a waveform diagram of the drive circuit shown in FIG.

FIG. 5 is a diagram showing a drive circuit of an electrochemical light control device according to a second embodiment of the present invention.

6 is a waveform diagram of the driving circuit shown in FIG.

FIG. 7 is a diagram illustrating a drive circuit of an electrochemical light control device according to a third embodiment of the present invention.

8 is a waveform diagram of the drive circuit shown in FIG.

FIG. 9 is a diagram illustrating a drive circuit of an electrochemical light control device according to a fourth embodiment of the present invention.

FIG. 10 is a waveform diagram of the drive circuit shown in FIG.

FIG. 11 is a diagram showing a drive circuit of an electrochemical light control device according to a fifth embodiment of the present invention.

12 is a waveform chart of the drive circuit shown in FIG.

FIG. 13 is a diagram illustrating a drive circuit of an electrochemical light control device according to a sixth embodiment of the present invention.

FIG. 14 is a waveform diagram of the drive circuit shown in FIG.

FIG. 15 is a configuration diagram showing an apparatus for adjusting the amount of incident light in a conventional image photographing apparatus.

FIG. 16A is a front view showing an example of the ND filter in front of the lens 33 shown in FIG. 15, and FIG.
(B) is a front view showing another example of the ND filter in front of the lens 33.

FIG. 17 is a front view showing a state in which the ND filter in the lens barrel shown in FIG. 15 is attached and detached.

[Explanation of symbols]

1 subject, 3 lens, 4 electrochemical dimmer (EC
Element), 5: iris meter (aperture), 6: imaging element, 12: H-bridge type switch circuit, 13: constant current circuit, 14: microcomputer, 20: waveform ROM, 31: subject, 32: ND filter, 33 ... Lens, 34 ND filter, 35 diaphragm, 36 imaging element, 41 plate glass, 42 frame, 43 electrolyte, 44 transparent electrode, 45
Annular electrode (counter electrode), 51: guide frame, 52: plate-like filter, 53: screw-in filter, 54: arm, T1: first transistor, T2: second transistor, T3: third Transistor, T4 ... 4th
Transistor, T5... Fifth transistor, R1.
1st resistor, R2 ... 2nd resistor, R3 ... 3rd resistor, R4 ... 4th resistor, R5 ... 5th resistor, R6 ...
Sixth resistor, R7 ... seventh resistor, R8 ... eighth resistor, R9 ... ninth resistor, R10 ... tenth resistor, R
11 ... eleventh resistor, C1 ... capacitor, O1, O
2, O3, O4 ... operational amplifier, A, B ... lead wire, V
1, V2, V3 ... power supply, V11, V22 ... variable power supply.

Claims (8)

[Claims] 1. An H-bridge type switch circuit in which an electrochemical dimming element for controlling light transmittance is connected to a bridge portion of an H-bridge, and a constant current which is connected to the H-bridge type switch circuit to draw in a constant current. A circuit for driving an electrochemical dimming device, comprising: a circuit; and a timing signal generation circuit that outputs a signal for opening and closing the H-bridge type switch circuit and the constant current circuit. 2. A timing signal generating circuit comprising: a first circuit for opening the H-bridge type switch circuit and the constant current circuit for a predetermined time so as to supply a current to the electrochemical light adjusting device so as to reduce light transmittance; And a second signal for opening the H-bridge type switch circuit and the constant current circuit for a predetermined time in order to supply a current to the electrochemical light control element so as to increase light transmittance. 3. The driving circuit for an electrochemical dimmer according to claim 2, wherein: 3. A voltage limiting circuit for changing from a constant current operation to a constant voltage operation when a current flows through the electrochemical light control element so as to increase the light transmittance and the internal resistance of the electrochemical light control element is large. 3. The driving circuit for an electrochemical dimming device according to claim 2, further comprising: 4. A voltage limiting circuit for changing a constant current operation to a constant voltage operation when a current flows through the electrochemical light control element so as to reduce the light transmittance and the internal resistance of the electrochemical light control element is large. 3. The driving circuit for an electrochemical dimming device according to claim 2, further comprising: 5. A method according to claim 1, wherein a current is supplied to the electrochemical light control device so as to increase the light transmittance, and when the internal resistance of the electrochemical light control device is large, a first current is changed from a constant current operation to a constant voltage operation.
When a current is applied to the electrochemical light control device so as to lower the light transmittance, when the internal resistance of the electrochemical light control device is large,
3. The driving circuit for an electrochemical dimming device according to claim 2, further comprising a second voltage limiting circuit for changing from a constant current operation to a constant voltage operation to the H-bridge type switch circuit. 6. The timing signal generating circuit according to claim 1, further comprising a ROM storing an arbitrary time function waveform of a constant current at the time of lowering the light transmittance of said electrochemical dimmer. The driving circuit for an electrochemical light control device according to any one of claims 2 to 5. 7. The timing signal generating circuit according to claim 1, wherein
7. The driving circuit according to claim 6, further comprising means for changing data read from the OM in accordance with the temperature of the electrochemical light control device. 8. A voltage applied to the H-bridge type switch circuit is applied to the electrochemical light control element when a current is applied to the electrochemical light control element so as to increase the light transmittance or the voltage is applied to the electrochemical light control element so as to reduce the light transmittance. 6. The driving circuit for an electrochemical dimming device according to claim 5, further comprising a circuit for changing the current in accordance with each of the current flows.