JPS63271892A - Driving of electrochromic element - Google Patents

Abstract

PURPOSE:To lengthen life of an element as well as to uniformalize a coloring and discoloring by applying a coloring and discoloring voltage controlled in a constant voltage to an electrochromic element, and controlling current to bellow a given value. CONSTITUTION:A coloring voltage controlled in a constant voltage with a voltage stabilization circuit 16 with a transfer switch 18 switched to the coloring side is applied to an electrochromic element 3. At that time, a rush current is prevented with current controlled to a constant current with a current stabilization circuit 17. In the same way, when discoloring, a discoloring voltage controlled to the constant voltage with the circuit 16 is applied to the element 3 with the switch 18 switched to the discoloring side. At that time too, an excess flowing of an electric quantity to the peripheral part of the element 3 is relaxed with current controlled to the constant current with the circuit 17. This constitution enables a coloring and discoloring to be uniformalized and life of the element to be lengthened even in a large element.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for driving an electrochromic device.

(Prior art and problems to be solved by the invention) A normal method for driving an electrochromic (hereinafter referred to as EC) element is to suddenly apply a predetermined constant voltage during coloring, as shown in FIG. Since the opposite constant voltage is suddenly applied during color embellishment, the EC element ends up applying J to the rectangular constant voltage.
It can be said that it is driven. An EC element with a small area (for example, 100 cn or less) can be favorably driven by this method.

However, when an EC element with a large area (for example, 100 m or more) is driven by the above method, the peripheral area of the EC element suddenly becomes darkly colored during coloring, as shown in Figure 3 for comparison of changes in light transmittance. The problem that the central part gradually becomes discolored becomes apparent. This is because EC elements have different characteristics, so when a rectangular voltage rises, an excessive rush current flows, as shown in Figure 3, and the transparent electrodes used in EC elements This is because, since the sheet resistance is large, the rush current is concentrated in the peripheral portion where the electrode is taken out, and an excessive amount of electricity is injected.

Further, when coloring is applied, a similar problem occurs in that the color suddenly disappears from the periphery of the EC element.

Furthermore, if excessive amounts of electricity are repeatedly injected into the peripheral area, bleeding or uneven coloring may remain in the peripheral area, or the peripheral area may peel off, resulting in a shortened lifespan of the EC element.

Structure of the Invention (Means for Solving the Problems) Therefore, in order to solve the above-mentioned problems, the present invention takes a technical measure of driving an electrochromic element with a constant voltage and a constant current.

(effect) First, a constant voltage controlled coloring voltage is applied to the EC element.

At this point, a rush current i~ naturally tends to flow through the capacitive load [C element], but in the present invention, since the coloring current is controlled at a constant current below a predetermined current, the same rush current is prevented. Therefore, injection of an excessive amount of electricity into the periphery of the EC element is alleviated, and the rate of coloring of the periphery of the EC element decreases and the color gradually becomes colored along with the central part.

After a predetermined period of time has elapsed since the application of the coloring voltage, the redox reaction in the EC element is saturated, so the coloring voltage reaches a constant voltage and becomes constant, the coloring current begins to decrease, and the degree of coloring becomes approximately steady state.

Next, a constant voltage controlled embellishing voltage is applied to the EC element.

In the present invention, since the embellishing current at this time is also controlled to be a constant current below a predetermined current, rush current is prevented. Therefore, the excessive amount of electricity injected into the periphery of the EC element is alleviated, and the coloring rate of the periphery of the EC element decreases, and the color gradually fades along with the central part.

When a predetermined period of time elapses from the time when the embellishing voltage is applied, the redox reaction in the EC element is saturated, so the embellishing voltage reaches a constant voltage and becomes constant, the embellishing current begins to decrease, and the embellishing degree becomes almost steady state.

(Example) Hereinafter, an example in which the present invention is embodied in an EC element for an automobile sunroof will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the sunroof 1 as an EC dimming plate of this embodiment has upper and lower substrates 2a and 2b made of reinforced inorganic glass plates with dimensions of 700m x 500mm x 2.5#.
and an EC element 3 formed between them and used in the transmission mode, with inter-electrode dimensions of 400 s x 400 m (cell area: 1600 cm).

The EC element 3 has a thickness of approximately 2000 Å formed on the lower surface of the upper substrate 2a.
an upper transparent electrode 4 made of an ITO (indium tin oxide) film, ■ an oxidized coloring layer 5 made of a polyaniline film with a thickness of about 6000 A formed by electrolytic polymerization on the lower surface of the upper transparent electrode 4, and ■ a lower substrate 2b. A lower transparent electrode 8 made of an ITO film with a thickness of approximately 2,000 thick formed on the upper surface; ■ Polyethylene oxygenide and 1M LiC are filled between the spacer 9a that supports the two plates 2a and 2b at a constant interval, and the oxidation coloring layer 5 and the reduction coloring layer 7.
It consists of a laminate of an ion donor layer 6 made of a gel electrolyte with a ratio of lO4/propylene carbonate in a ratio of 1:6, and the EC74 child 3 is sealed with a hard sealing material 9b made of epoxy resin. ing.

Transparent electrodes 4, 8 on the upper and lower substrates 2a, 2b
have a sheet resistance of about 20Ω/hole, and conductive paste 10.11 is applied to their − side, and the same conductive paste 10.
．． Lead wires 12 and 13 for applying a driving voltage are soldered to 11.

Next, the stabilized power source 14 for driving the EC element 3 will be explained.As shown in FIG.
is a power supply source 15 such as a battery, alternator, dynamo (including a transformer, rectifier circuit, smoothing circuit, etc. in the case of an AC source) and an EC element 3 which is a type of capacitive load.
Keep the coloring voltage and embellishing voltage applied to almost constant (
A voltage stabilizing circuit 16 for keeping the coloring current and decoloring current flowing through the same EC cord 3 almost constant (particularly keeping it below a predetermined current) It is equipped with Stabilized power supply 1 of this embodiment
4 outputs a constant voltage of 1.4 and a constant current of 400 mA when coloring, and outputs a constant voltage of 2.1 V and a constant current of 600 m when coloring.
It is adjusted and set to output a constant current of A.

Then, the lower transparent electrode 8 of the EC element 3 is connected to the ground terminal (OV) of the stabilized power supply 14 via the lead wire 13.
The upper transparent electrode 4 is connected to a positive voltage terminal or a negative voltage terminal of the stabilized power source 14 via a coloring/decoloring changeover switch 18 and a lead wire 12 .

Next, a method for driving the EC element 3 using the stabilized power source 14 will be explained.

(2) At the time of coloring, first, the changeover switch 18 is turned on to the coloring side, and a coloring voltage controlled at a constant voltage by the voltage stabilizing circuit 16 of the stabilized power source 14 is applied to the EC element 3. At this time, rush current tends to flow through the EC element 3 which is a capacitive load, but in this embodiment, the current stabilizing circuit 17 of the stabilized power supply 14
Since the coloring current is controlled at a constant current of 400 mA or less as shown in FIG. 2, the same rush current 1~ is prevented.

Along with this, the falling speed of the coloring voltage decreases.

Therefore, the injection of an excessive amount of electricity into the peripheral area of the EC element 3 as described above is alleviated, and as shown in FIG. decreases and becomes gradually colored along with the central part.

When about 20 seconds pass from the time when the coloring voltage is applied, the redox reaction in the EC element 3 is saturated, so the coloring voltage is 1.4.
When a constant voltage of v is reached and becomes constant, the coloring current begins to decrease, and the light transmittance decreases to about 10% at the periphery and about 12% at the center, and the degree of coloring becomes almost steady.

■ When approximately 30 seconds have passed since the changeover switch 18 was turned on during color embellishment,
Switch the changeover switch 18 to the embellished side, and stabilize the power supply 1.
An embellishing voltage controlled at a constant voltage by the voltage stabilizing circuit 16 of 4 is applied to the EC cable 3. At this time, the current stabilizing circuit 17 of the stabilized power supply 14 adjusts the embellishing current to 60
The constant current is controlled to be 0 mΔ or less, and the falling speed of the decoloring voltage decreases accordingly.

Therefore, the excessive amount of electricity injected into the periphery of the EC element 3 as described above is alleviated, and as compared with FIG. 2, the decoloring speed of the EC element 3 is reduced. The color gradually fades along with the central part.

When about 15 seconds have elapsed since the application of the color erasing voltage, the redox reaction in the EC cell 3 is saturated, so the coloring voltage is -2,
When a constant voltage of 1 V is reached and becomes constant, the embellishing current begins to decrease, and the light transmittance increases to about 78% at the periphery and about 76% at the center, and the degree of decolorization becomes almost steady.

As described above, according to the present embodiment, injection of excessive electricity m into the periphery of the EC element 3 is prevented, and coloring and decoloring due to excessive oxidation-reduction reactions in the periphery are thereby prevented. The uniformity of the chromaticity or degree of embellishment improves when the embellishment progresses and reaches a steady state.

Further, even if coloring and decoloring are repeated, bleeding or color unevenness will not remain in the peripheral area, and the peripheral area will not deteriorate and peel, so that the life of the EC element 3 can be extended.

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) The present invention is particularly effective when embodied as a method for driving an EC element with an area of 100 cd or more;
Of course, it is also possible to implement an EC element with a smaller area.

(2) @The absolute values of the coloring voltage and the decoloring voltage may be controlled to be the same constant voltage, or the coloring current and the embellishing current may be controlled to be the same constant current.

(3) It can be implemented as a liquid type or all solid type EC element, or as a foul mode EC element.

Effects of the Invention (Details above) As mentioned above, the present invention not only improves the uniformity of the degree of coloring and coloring of the EC element, but also prevents staining, uneven coloring, and peeling of the EC element, thereby extending the life of the EC element. It has the excellent effect of being able to be extended.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment embodying the present invention, Figure 1 is an overall schematic diagram showing an EC element and an electric circuit used for its driving method, and Figure 2 is an overall schematic diagram showing the electric circuit used for the EC element and its driving method. FIG. 3 is a time chart diagram showing temporal changes in current, voltage applied to the EC element, and light transmittance in the peripheral and central parts of the EC element. Moreover, FIG. 3 is a time chart diagram showing temporal changes in voltage, current, and light transmittance in the conventional example. 3... Elec l ~ Lochromic ([C) element, 14.
... Stabilized power supply, 16... Voltage stabilization circuit, 17...
・Current stabilization circuit. Patent Applicant Toyoda Gosei Co., Ltd. Toyota Central Research Institute Representative Person Patent Attorney 1) Inversion” n) 20 seconds 10 seconds 18 seconds Time →

Claims (1)

[Claims] 1. A method for driving an electrochromic device, comprising driving the electrochromic device with a constant voltage and a constant current.