JP2503519B2 - Electrochemical device driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a driving method of an electrochromic device (hereinafter abbreviated as ECD), in particular, by applying a conduction voltage to an ECD having a memory property, the ECD The present invention relates to a method for changing the concentration state of the above from the first concentration state to the second concentration state.

[Prior Art] In general, an ECD is formed of a pair of transparent electrode layers, at least one of which is transparent, and an electrochromic layer (hereinafter, abbreviated as an EC layer) disposed between them, and is of a size that can be obtained from a dry battery. When a driving voltage is applied between the pair of electrodes, it develops color, and when a voltage of opposite polarity is applied or the electrodes are short-circuited, the color disappears and the original colorless and transparent property is restored.

Moreover, since the ECD can control the color density by changing the voltage value applied between the electrodes, it is currently being studied as a control element for the amount of transmitted or reflected light.

Hereinafter, a conventional method for changing the color density state of the ECD will be described with reference to FIGS. 3 and 4.

Here, the EC layer of the ECD can be regarded as a kind of capacitor, the color density is considered to be proportional to the voltage across this capacitor, and the ECD can be represented by an equivalent circuit as shown in FIG. Therefore, here, the operation of changing the color density state of the ECD to the desired color density state will be described by replacing it with the voltage applied across the capacitor C in FIG. In the figure, C is a capacitor having a capacitance C corresponding to the ED layer, and R is a resistor having a resistance value R corresponding to the transparent electrode.

FIG. 4 shows the relationship between the voltage V applied to the EC layer and the voltage application time T when a predetermined voltage is applied to the ECD.

In the graph of (A), from the first concentration state where the initial voltage V1 is applied to the EC layer, the voltage V2 having the relationship of V2> V1
The change over time is shown in the case of transition to the second concentration state, which is caused by. The graph of (B) shows that the voltage V4 of V4 <V1 is applied from the first concentration state similar to (A). The change over time in the transition to the second concentration state is shown.

Conventionally, when transitioning from the first concentration state in which the initial voltage V1 is applied to the EC layer to the second concentration state in which the voltage V2 having the relationship of V2 <V1 is applied, V2 at the start of transition ( By applying to the ECD from time T ₀ ) and connecting this state, the voltage applied to the EC layer (capacitor C) is V2.
Had been transitioned to. The transition characteristic by this method is represented by the broken line a in FIG. From the first concentration state where the initial voltage V1 is applied to the EC layer, V4 <V1
Even when a transition is made to the second concentration state in which the voltage V4 is applied, V4 is applied to the ECD from the start of the transition (time T ₀ ) and the state is connected to apply to the EC layer (capacitor C). The voltage is changed to V4, and the transition characteristic by this method is represented by the broken line a in FIG. 4 (B).

Here, from the first concentration state in which the voltage across the capacitor C at the time t = 0 is V1, the voltage of the capacitor C is
Taking the case of transitioning to the second concentration state of V2 as an example, if the voltage across capacitor C when voltage V2 is applied to capacitor C for t hours is Vt, then Vt is Vt = V2 + (V1-V2 ) Exp (-t / RC) ... It can be expressed as (1). Therefore, it can be seen that the time required for transition to the target voltage V2 is determined by the magnitudes of R and C. Of course, the same applies when the target voltage is V4.

However, ITO (Indium-Tin-Oxid) is commonly used for transparent electrodes.
e) ITO that uses electrodes and corresponds to R in the above formula (1)
Since the (transparent electrode) has a high resistance value, there is a drawback that it takes a long time to change the voltage applied to the EC layer, as can be seen from the broken line a.

Therefore, at present, when a transition is made from a first concentration state obtained by applying the initial voltage V1 to a second concentration state obtained by applying a voltage V2 higher than V1, a voltage higher than V2 at the start of transition When changing to the second concentration state obtained by applying V3 while applying the voltage V4 lower than the initial voltage V1, the time required for concentration transition is applied by applying the voltage V5 lower than the voltage V4 to the ECD. The method of shortening is used. The transition characteristic by this method is represented by the broken line b in FIG.

As is clear from the above description and FIGS. 4A and 4B, when the voltage applied to the EC layer reaches the target voltages V2 and V4, V3> V2 or V5 <V4 By applying the excessive overvoltages V3 and V5 to the ECD, the time required to set the voltage applied to the EC layer to the target voltage V2 or V4 becomes short. That is, the transition time required for transition of the ECD to the second concentration state can be shortened.

[Problems to be Solved by the Invention] However, according to the method as described above, during overvoltage application,
Since it is not possible to accurately know the time required to reach the target voltage V2 or V4 without detecting the voltage of the EC layer, an overvoltage of the target voltage V2 or V4 or more is applied to the EC layer.
There is a problem that the layer deteriorates or the voltage application is stopped before the desired voltages V2 and V4 are reached, and the effect of shortening the time by applying the overvoltage is not sufficiently exerted.

Such a problem is particularly remarkable when the initial voltage V1 of the EC layer and the target voltages V2 and V4 are expressed as intermediate values that are not fixed values.

The present invention has been made in view of such points, and
An object of the present invention is to provide an electrochromic device driving method capable of favorably shortening the transition time to the second concentration state without degrading the layer.

[Means for Solving Problems] The electrochromic device driving method according to the present invention monitors the first voltage actually applied to the electrochromic layer and responds to the first voltage and a desired color density. While comparing with the second voltage; based on the comparison result, when the first voltage is lower than the second voltage, a predetermined overvoltage higher than the second voltage, and the first voltage is higher than the second voltage. A predetermined overvoltage lower than the second voltage when the voltage is higher than the above voltage; the application of the overvoltage is stopped when the difference between the first voltage and the second voltage reaches a predetermined allowable range. The technical point is to do so.

[Operation] In the present invention, the first voltage actually applied to the electrochromic layer is monitored and compared with the second voltage corresponding to the desired color density, so that an overvoltage that deteriorates the EC layer is actually measured. Satisfactorily without applying to the second
The transition to the concentration can be performed.

In addition, since the overvoltage is sufficiently applied between the electrodes for the required time, the transition time to the second concentration can be optimally shortened.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows the configuration of an apparatus (circuit) used in the electrochromic element driving method of the present invention. In the figure, 10 is an ECD equivalent circuit similar to the above-mentioned conventional technique, C is a capacitor of capacitance C corresponding to the EC layer, R
Is a resistance having a resistance value R corresponding to the transparent electrode. One electrode of the ECD is grounded and the other is the common terminal 12a of the switch 12.
It is connected to the.

The switch 12 has a common terminal 12a connected to the ECD, and either the selection terminal 12b connected to the voltage source 14 or the selection terminal 12c connected to the comparator 16 is connected to the common terminal 12a. It is configured so that one can be selected.

The voltage source 14 is configured to output one of the coloring voltage VF and the erasing voltage VR to the selection terminal 12b of the switch 12, and the coloring voltage VF is used for any concentration that should be applied to the EC layer. It is set to a voltage value that is higher than the state voltage and does not deteriorate the ECD, and the other decoloring voltage VR is EC
Below the voltage of any concentration state to be applied to the layer,
Moreover, the voltage value is set so as not to deteriorate the ECD.

The voltage comparator 16 includes a comparison terminal 16a connected to the selection terminal 12c of the switch 12 and a comparison terminal 1 to which the reference voltage Vs is applied.
6b and is configured so that the magnitude of the voltage applied to the comparison terminals 16a and 16b can be compared.Furthermore, based on this comparison result, the voltage output from the voltage source 14 is decolorized with the coloring voltage VF. Either one of the working voltage VR is selectively controlled.

Next, referring to FIG. 2, the operation when the first concentration state in which the voltage V1 is applied to the EC layer is changed to the second concentration state in which the voltage V2 (V2> V1) is applied Will be explained step by step.

FIG. 2 shows the fourth example referred to in the above-mentioned prior art.
Similar to the figure, the relationship between the voltage V applied to the EC layer and the voltage application time T is shown.

The voltage Vs of the comparison terminal 16b of the voltage comparator 16 is set to Vs = V2 in advance, and the common terminal 12a of the switch 12 and the selection terminal 12c are connected. At this time, since the input impedance of the voltage comparator is generally large, the voltage applied to the EC layer at terminal 16a, that is, E
The voltage Vc across the capacitor C in the CD equivalent circuit appears.

Next, in the voltage comparator 16, the voltage Vc of the terminal 16a and the voltage V2 of the terminal 16b are compared, and if the comparison result is Vc <V2, Vc> v2 so that the output of the voltage source 14 becomes VF. In this case, the voltage source 14 is controlled so that the output of the voltage source 14 becomes VR.
(Step 1) Next, the common terminal 12a of the switch 12 and the selection terminal 12b are connected for a predetermined time, and an overvoltage of VF or VR is applied to the ECD. (Step 2) At this time, if VF is applied to the ECD, the capacitor C
When the (EC layer) is charged and the voltage Vc increases, the color density of the ECD increases. Conversely, when VR is applied to the ECD, discharge occurs in the capacitor C (EC layer) and the voltage Vc
Decreases, and the color density of ECD decreases.

Next, after performing the operation of applying the overvoltage in the step 2 for a predetermined time, the common terminal 12a of the switch 12 and the selection terminal 12c are connected again, and the procedure returns to the comparison operation of the step 1 and the changed value of Vc and V2
Compare. Then, the above steps 1 and 2 are performed.
Alternately repeated until the difference between the voltages of Vc and V2 reaches within a predetermined allowable range.

Then, when the difference between the voltages of Vc and V2 reaches within a predetermined allowable range, the common terminal 12a of the switch 12 is set to whichever selection terminal 1
The transition of the color density of the ECD is ended by not opening the connection with 2b and 12c and setting the open state. (Step 3) and thereafter, since the ECD has a memory property, even if the common terminal 12a of the switch 12 and the selection terminals 12b and 12c are opened, the voltage of the EC layer is within a predetermined allowable range near V2, That is, the color density of the ECD can be maintained in a desired state.

As described above, according to the above embodiment, the step 1 of comparing the actual EC layer voltage Vc with the EC layer voltage V2 corresponding to the desired color density by the comparator 16 and the comparison of the comparator 16 Since there is a step 2 of applying and stopping an overvoltage based on the result, and both steps are alternately operated, the voltage of the EC layer can be favorably changed from the initial voltage V1 to V2 in a short time, and thus the EC voltage can be improved.
The effect is that the transition time of D to the desired color density can be shortened satisfactorily.

Note that the present invention is not limited to the above-described embodiment, and even after the difference between the voltages of Vc and V2 reaches a predetermined allowable range, the operation of comparing Vc and V2 as described above is continued, When the value of Vc changes due to some reason, the process may be returned to the operation of step 3 and a series of operations may be repeated.

Further, as another method of the step 3, the selection terminal 12d to which the voltage V2 is applied is separately provided to the switch 12, and once the difference between the voltages Vc and V2 reaches the predetermined allowable range, the terminal 12 is
Connect C and 12d and V2 to ECD until Vc and V2 are completely equal
May be applied, and after that, connect the operation of comparing Vc and V2, and when the value of Vc changes for some reason, connect terminals 12c and 12d again and apply V2 to ECD. You may do it.

[Effects of the Invention] As described above, the present invention has a remarkable effect that the transition time to the second concentration can be favorably shortened without degrading the EC layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an apparatus using a method according to an embodiment of the present invention, FIG. 2 is a graph showing the operation of the embodiment, and FIG. 3 is related to the present invention and the prior art. FIG. 4 is an equivalent circuit diagram of the ECD and is a graph showing the operation of the prior art. "Explanation of symbols for main parts" 10 …… ECD equivalent circuit, 12 …… Switch, 14 …… Voltage source, 1
6 …… Comparator.

Claims (1)

(57) [Claims] 1. A method of driving an electrochromic device, wherein a first voltage is applied between a pair of electrodes of the electrochromic device to cause a transition from a first concentration state to a second concentration state. While monitoring the first voltage actually applied and comparing the first voltage with the second voltage corresponding to the desired color density, the first voltage is changed to the second voltage based on the comparison result. A predetermined overvoltage higher than the second voltage when the voltage is lower than the second voltage, and a predetermined overvoltage lower than the second voltage when the first voltage is higher than the second voltage. The method for driving an electrochromic device, characterized in that the application of the overvoltage is stopped when the difference between the first voltage and the second voltage reaches a predetermined allowable range.