JPH045992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for driving an electrochromic device.

Traditionally, electrochromic devices (ECD)
This method utilizes the fact that when voltage is applied, the color changes or disappears due to an oxidation-reduction reaction. The device structure is such that a transparent conductive film is formed on a substrate such as glass, and an EC layer made of an electrochromic substance and an electrolyte is sandwiched between a transparent electrode formed on another substrate. When a coloring voltage is applied to the transparent electrodes on both substrates, the EC layer is colored, and when a reverse voltage is applied, it becomes transparent and disappears.

In conventional ECD drive devices, both electrodes of the ECD remain open or shorted when the drive circuit is powered off. However, when driving the ECD, side reactions may occur due to overvoltage, etc. Even if a decoloring state is achieved after applying a decoloring voltage to the ECD, the ECD
If both electrodes are left open or shorted for a long time, the colored state may return.

Also, the EC layer is colored by reduction.
Layer A, solid electrolyte layer B, EC colored by oxidation
In an all-solid-state ECD that consists of three layers, layer C, and only one EC layer A is patterned,
It is patterned when a coloring voltage is applied.
EC layer A and unpatterned EC layer C
The portion facing the EC layer A is colored, and the combined color is observed. If coloring continues for a long time, EC layer C
The ions involved in coloring diffuse into the part adjacent to the part facing the EC layer A and are colored. Coloring caused by diffusion has a slow response to erasing, so it remains erased even if a color erasing voltage is applied for a certain period of time.

Such residual coloring not only degrades the quality of the display element but also causes misperception of the display. Particularly when using a transparent type ECD, the remaining parts will significantly obstruct visibility and become unusable.

For this reason, a decoloring voltage is always applied even when the ECD is not driven to prevent the ECD from remaining unerased.
It is possible to activate the ECD drive circuit, but
If the ECD drive circuit is constantly operated, the power consumption of the drive circuit itself becomes large.

The purpose of the present invention is to apply a decoloring voltage to the ECD at all times when the ECD is not driven, but to provide an ECD with extremely low power consumption.
The purpose of the present invention is to provide a driving device.

The above problem has been solved according to the present invention by an ECD drive device which is provided with an erasing voltage circuit which consumes very little power during operation, separately from the ECD drive circuit. The configuration of the ECD drive device of the present invention includes a drive circuit for coloring and decoloring an electrochromic element, a switch having a first state in which the drive circuit is activated and a second state in which it is inactive, and a switch in which the switch is in a second state. and a color erasing voltage circuit which operates when the electrochromic element is in the state and applies a color erasing voltage to the electrochromic element via a high impedance circuit formed between the power supply terminals.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 13 shows a block diagram of a first embodiment of the invention. An ECD drive circuit 2 and a color erasing voltage circuit 3 exist separately, and during ECD drive, the ECD drive circuit 2 operates through switches SW ₁ and SW ₂ in which the power supply 1 and ECD 4 are linked.
are tied together. If the switches SW ₁ and SW ₂ are connected to the erasing voltage circuit 3 side, the ECD 4 and the erasing circuit 3 are connected, the drive circuit 2 is turned off, and the erasing voltage is applied to the ECD 4. Figure 4 is a circuit diagram of the first embodiment, in which switches SW1, _SW2 , _SW3 ( _SW2 , _SW3
constitutes SW _x in Figure 1. ) is in the state shown by the solid line in the figure, the voltage from the power supply 1 is applied to the ECD drive signal circuit 2A, and the drive voltage generation circuit 2B is
Generates a voltage of V _R. The ECD 4 is colored and decolored by the coloring signal S _C or decoloring signal S _B of the ECD drive signal circuit 2A. When the signal S _C becomes high level, the transistor Tγ 4 is turned on through the transistor Tγ ₁ and the inverter I ₁ , and _a coloring voltage is applied to the ECD 4 to color the ECD 4 . When the signal S _B is at a high level, the transistors Tγ ₃ and Tγ ₂ are turned on, and a decoloring voltage whose polarity is opposite to that of the coloring voltage is applied. When both signals S _C and S _B are at low level, transistors Tγ ₁ to Tγ ₄ are all turned off and ECD
Both terminals of 4 are in an open state and have a memory property and continue to maintain the current state. Now switch SW1
When connected to the dotted line side, a voltage is applied to the decoloring circuit 3 consisting of diodes D1 to D4 and resistor γ1. Switches SW ₂ and SW ₃ are also linked and connected to the dotted line side, and the ECD
A predetermined decoloring voltage, which is the voltage between the terminals of the resistor γ1, is applied to the resistor γ1. The diodes D1 to D4 are used to keep the voltage applied to the ECD 4 itself constant even if the resistance of the ECD 4 changes during erasing, and to determine the magnitude of the erasing voltage. That is, diodes D1, D
Since the voltage between the terminals of each of resistors 2, D3, and D4 is constant as a forward voltage, the voltage between the terminals of resistor γ1 is maintained constant. The resistor γ1 is selected so that the current consumption of the decolorizing voltage circuit 3 is not too large compared to the natural current of the battery. Since the ECD4 is a charge injection device, it can be regarded as a resistor with a large resistance value when the color density does not change significantly, for example when the decolored state is maintained.
The power consumption of the ECD 4 itself when the decoloring voltage is continuously applied is sufficiently small.

With the above circuit, by applying a decoloring voltage of a predetermined magnitude to the ECD when the ECD is not driven, the ECD
Coloring can be suppressed, and the power consumption at that time is small. Furthermore, since the erasing circuit 3 is disconnected during driving, a driving method that utilizes memory properties is also possible.

FIG. 2 is a block diagram of a second embodiment.

The difference from the first embodiment is that the erasing voltage circuit 3 operates regardless of whether the ECD drive circuit 2 is on or off.

FIG. 5 is a circuit diagram of the second embodiment, and the switch
When SW1 is closed, ECD is activated as in the first embodiment.
is driven. The decoloring voltage circuit 3 consisting of resistors γ1 to γ3 remains in operation regardless of whether the switch SW1 is opened or closed. When the coloring voltage is applied to the ECD 4, the decoloring voltage circuit 3 is activated at the same time.
Since the values of the resistors γ1 to γ3 are selected so that the output impedance is much larger than that of the ECD drive circuit 2, the erasing voltage circuit 3 can be ignored when the ECD drive circuit 2 is operating. However, it is not possible to drive with memory performance in mind. switch SW1
When is opened, ECD drive circuit 2 is turned off.
A decoloring voltage is applied to the ECD.

The second embodiment requires fewer switches than the first embodiment, and even when a large leak occurs in the ECD, the erasing current of the erasing voltage circuit 3 is set to a certain value (determined by resistors γ1 and γ3). , the larger these resistances are, the smaller the flow of the bleaching current will be (if the resistance were infinite, the current would be zero), preventing battery waste.

FIG. 3 is a block diagram of a third embodiment.
A part of the drive circuit 2 of the ECD 4 also serves as a color erasing voltage application circuit, and the color erasing circuit is activated when the power source 1 of the drive circuit is turned off. FIG. 6 shows an example of the circuit.

When the switch SW1 is closed, the ECD drive signal circuit 2A is activated, and when the signal S _c is at a high level and the signal S _B is at a high level, the transistor Tγ4 is turned on and a coloring voltage is applied to the ECD4. Thereafter, when the signal S _C is at a low level and the signal S _B is at a high level, the terminal of the ECD 4 is in an open state and the colored state is maintained due to the memory property. When S _B is low level, transistor Tγ5 turns on and ECD
A decoloring voltage is applied to 4. Resistor R3 is resistance R2
Since it is sufficiently large compared to the switch SW1
When R3 is closed, resistor R3 is ignored.

When the switch SW1 is opened, a base current flows through the resistors R2 and R3 and activates the transistor Tγ5. Therefore, a decoloring voltage is applied to the ECD. The resistor R3 can also be included in the drive signal circuit 2A as shown in FIG. In this case, it becomes possible to apply a decoloring voltage without using almost any new circuit.

As described above, the present invention utilizes a low power consumption decoloring voltage circuit provided separately from the ECD drive circuit.
By constantly applying a color erasing voltage when the ECD drive device is not driven, it is possible to prevent the ECD from returning to color, or to erase the remaining color of the ECD. This is achieved without increasing power consumption when not in use.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an ECD drive device according to a first embodiment of the present invention, FIG. 2 is a block diagram of an ECD drive device according to a second embodiment of the present invention, and FIG. 3 is a block diagram of an ECD drive device according to a second embodiment of the present invention. Block diagram of the ECD drive device of the embodiment,
4 is a more specific circuit diagram of the block diagram of the first embodiment shown in FIG. 1, FIG. 5 is a more specific circuit diagram of the block diagram of the second embodiment shown in FIG. Third
A more specific circuit diagram of the block diagram of the third embodiment shown in the figure, and FIG. 7 is a circuit diagram showing a modification of the circuit example of FIG. 6. [Explanation of symbols of main parts], Electrochromic element drive circuit...2, Switch...SW ₁ ,
SW ₂ , color erasing voltage circuit...3.

Claims (1)

[Scope of Claims] 1. A drive circuit for coloring and decoloring an electrochromic element, a switch having a first state in which the drive circuit is activated and a second state in which it is inactive, and a switch in which the switch is in the second state. an electrochromic device comprising a color erasing voltage circuit which operates when the electrochromic device is in operation and applies a color erasing voltage to the electrochromic element via a high impedance circuit formed between power supply terminals, the power consumption of which is lower than that of the driving circuit; Drive device. 2. In the electrochromic device driving device according to claim 1, the color erasing voltage circuit includes a high impedance element connected between power supply terminals, and the color erasing voltage is generated by the high impedance element. A device characterized in that the device is obtained by dividing the power supply voltage. 3. In the electrochromic element driving device according to claim 1, the erasing voltage circuit includes a transistor connected in series with the electrochromic element between erasing power supply terminals, and the base of the transistor is connected to the drive circuit through a low impedance element and to the collector of the transistor through a high impedance element, the transistor being connected to the low impedance when the drive circuit is in operation in the first state of the switch. and is turned off via the high impedance element, and when the drive circuit is inactive in the second state of the switch, is turned on via the high impedance element to apply a color erasing voltage to the electrochromic element. device to do.