JPS62212630A - Driving method for dimming body - Google Patents

Abstract

PURPOSE:To prevent ITO from being reduced by inhibiting a negative voltage which is higher than a constant voltage from being applied to an oxide transparent electrode at the time of at least decoloring. CONSTITUTION:A voltage is applied between the oxide transparent electrode 2 of a display electrode substrate 1 and the oxide transparent electrode 5 of a counter electrode substrate 4 and the EC material 3 of the display electrode substrate is used in a colored/decolored state. The coloring and decoloring are performed by constant current driving, but the applied voltage should be lower than the certain voltage during the decoloring. This constant voltage is only determined properly within a range wherein ITO is not reduced, but when the voltage is made too low, the decoloring speed decreases, so the voltage is set high within ITO is not reduced. The voltage applied during the decoloring is easily limited by providing a constant current driving circuit with a voltage limiter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for driving a light control body using an electrochromic (EC) substance.

[Prior Art] As light control bodies that utilize the EC phenomenon, light control windows, light control mirrors, etc. are known, and the following methods are known as driving methods thereof.

■ Constant-voltage driving method This driving method is suitable for EC display elements because the circuit is simple and there are fewer problems when the area to be colored or erased is small, but coloration occurs due to changes in the potential of the EC material over a long period of time. There is a tendency for the concentration of to change.

(2) Constant current drive method - Uniform coloring and decoloring is possible, but one circuit is complicated, and it is not often used for EC display elements with a large number of drive segments.

■ Constant potential drive method A reference electrode is required, and the circuit becomes complicated.

■Charge Transfer Driving Method Electrodes are required to transfer charges for coloring the EC material. Therefore, by driving the EC display element so that the area of the colored segment in the display segment is always constant, the EC display element can be driven without providing a separate electrode for charge transfer. However, as with a light control body, almost the entire surface is covered with one solid electrode, and it cannot be used for purposes of simultaneously coloring or decoloring the entire surface.

[Problems to be Solved by the Invention] For this reason, a constant voltage driving method or a constant current driving method is adopted as a driving method for a light control body having a large surface and one large electrode.

However, the dimmer is different from the display element;
Since the JC pole needs to be transparent or specularly reflective,
It is not possible to use a large capacitance electrode such as carbon and manganese dioxide as used in the display element f for the counter electrode.For this reason, it takes longer for the light control body to change color and fade compared to the display element. , it is necessary to apply a high voltage to drive the same area.

In addition, the light control body has a much larger area than one normal display element, and it is necessary to color and erase the entire surface of the element at the same time. This was also a factor in increasing the applied voltage.

For this reason, in this constant voltage driving method, the voltage applied during decolorization must be increased to a certain extent, and when the color is relatively darkly colored, when a constant voltage is applied during this decolorization, the voltage applied to the oxide transparent electrode is high. When a voltage is applied, abnormalities may occur in the oxide transparent electrode.

For example, EC#l! Ij! An example of a light control body in which tungsten oxide is used as j, ITO (tin oxide-indium oxide) is used as the oxide transparent electrode, and the counter electrode is explained will be explained.

When this light control body is colored so that its transmittance is about 10%, the potential of its W(h is about -0.7V with respect to the reference electrode (SCE).

When a voltage of about -1.2 V is applied to erase the color of this dimmer, the XTO of the counter electrode becomes -1.8 with respect to SCH.
The voltage is approximately V. ITO is approximately −1 relative to SCH in organic electrolytes, as detected in portammetry.
, 8 to -2, starting to be reduced around Ov. For this reason,
Reduction of ITO on the counter electrode begins, and as the device continues to be used, total indium is precipitated. Since this precipitated indium is not transparent, it is visually recognized as a defect.

In addition, in the electrolyte, Ho was present in the 1w03 membrane width.
is eluted by replacing Lio, and the reaction between this Ho and the precipitated indium generates hydrogen gas, producing bubbles, which are also visually recognized as defects. moreover,
103Il of this part where bubbles exist! A defect that coloring and decoloring of No. 2 will not occur will also occur.

In the constant current driving method, since the device is driven with a constant current value, the applied voltage becomes high, especially at the end of the erasing process, and there is a risk that a voltage higher than the i-source potential of ITO will be applied. This is also because, as mentioned above, the light control body has a large area and requires a high voltage when driving with a large current.

In addition, when the R color density is increased or when light is irradiated to the light control body, the potential of 103 moves significantly negative, so it becomes more I
They tended to be IIMs.

There is also a driving method that combines these driving methods.

For example, a constant current coloring/constant voltage decoloring driving method is also known, but it has the same problems as the constant voltage driving method and the constant current driving method when decoloring.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a display electrode substrate in which an EC material layer is formed on an oxide transparent electrode, and an oxide transparent electrode. In a method of driving a light control body in which a light control body is formed by arranging a counter electrode substrate so that the electrode surfaces face each other and sandwiching an electrolyte between these electrodes and driving the light control body to change color and decolor with a constant current, at least when decoloring This is a method for driving a light control body characterized in that a negative voltage higher than a certain voltage is not applied to an oxide transparent electrode.

The light control body used in the present invention may be a transmission type such as a light control window, or a reflection type such as a light control wave.

FIG. 1 is a sectional view showing the basic structure of a light control body according to the present invention.

In the figure, a substrate 1 made of glass, plastic, etc., and a transparent oxide electrode 2 made of In20x, 5n02, etc. formed on its inner surface. ECvh that colors and fades in the visible light range such as W (h)
1 on the inner surface of the substrate 4;
11203, the periphery is sealed with a sealing material 7 via an electrolyte 8 so that the electrode surfaces face each other with a counter electrode substrate on which a counter electrode 5 having a transparent electrode of oxide such as SnO2 is formed. By applying a voltage between the oxide transparent electrode of the display electrode substrate and the oxide transparent electrode of the counter electrode substrate, the EC material of the display quasi-electrode substrate is used by coloring and decoloring it.

In an uninvented driving method for a light control body, constant current driving is performed for both coloring and decoloring, but when decoloring, the applied voltage is set to be below a certain voltage. This constant voltage is I
It may be set as appropriate within a range in which TO is not reduced, but if it is set too low, the decoloring speed will usually decrease, so it is set high within a range in which ITO is not reduced.

Specifically, since the reduction of ITO occurs in the organic electrolyte at about -1.8 to -2.OV with respect to the reference electrode SCH, the reduction should be about -1.5 to -1.0 V. However, since this value varies depending on the electrolyte used and the type of oxide transparent electrode, it may be set appropriately so that reduction of ITO does not occur.

In addition, when using under strong irradiation such as direct sunlight, the potential of 1w03 shifts to the negative side, so this voltage should be lower than in normal cases, for example about -
It is preferable to set it to about 1.2 to -0.8v.

Limiting the voltage applied during such decoloring can be easily achieved by providing a voltage limiter in the constant current drive circuit.

In the present invention, in order to avoid any adverse effects even if the color is completely erased, the voltage is limited as described above when erasing the color, but it is also possible to limit the voltage when coloring. In the case of dimmers, etc., the supplied current value is high, so there is a risk of a higher voltage being applied near the electrode terminals than in the center of the element, or a high voltage being applied at low temperatures. There is sex. By applying a high voltage during this coloring, IT
This is because adverse effects other than O reduction may occur, such as decomposition of some components of the electrolyte and deterioration of the EC material.

In the present invention, in the case of a transmissive type light control body, both substrates are transparent substrates such as glass or plastic, and in the case of a reflective type light control body, if there is a reflective member on the inner surface of the substrate, the substrate on the back side is ceramic or metal. It is also possible to use an opaque substrate such as, but if there is a reflective member outside the substrate on the back side, a transparent substrate is used as in the case of a transmissive type.

On one side of this substrate, a layer of solid EC material such as W03 or No02 is formed and used as a display electrode substrate.Normally, W03 is preferable from the viewpoint of its durability, usage history, etc. It is also possible to implant Li ions in advance. °This display electrode substrate usually has In20z on its entire surface.
, 'It has a laminated structure in which a transparent oxide electrode such as JnOz is formed, and a layer of ECoy is formed on top of it, and this oxide transparent electrode is connected to a terminal for conductive connection with the outside. However, it is also possible to laminate a metal lead on the oxide transparent electrode.

In addition, on the other substrate, a counter electrode having a transparent electrode of an oxide such as In2O3, 51102, etc. is formed.In an ECD as a normal display element, the counter electrode is hidden from view by the background plate, Carbon on transparent electrode, carbon and manganese dioxide, EC#! It can be used by laminating J quality or the like. However, it is difficult to use such materials in products where the counter electrode is transparent, such as a light control body. Therefore, it is necessary to use only an oxide transparent electrode as the counter electrode, or to use a transparent oxide electrode on top of the oxide transparent electrode. E uses an EC substance that does not change color or decolor in the visible light range when applied with either positive or negative voltage, and changes color and decolors when a voltage of opposite polarity to the display electrode is applied.
It is possible to use C material or to arrange the above-mentioned counter electrode material partially, for example, in a linear form. However, using some kind of material by layering it on an oxide transparent electrode is
Currently, there is a lack of durable materials, the appearance is poor, and there is a tendency to not be able to obtain sufficient quality. For this reason, it is preferable to use an oxide transparent electrode such as In2O3 or 5n02 for Qi as the counter electrode, and to contain a redox agent in the electrolyte. Gold Ji for reflective layer and low resistance! The wires can also be stacked.

Specifically, the oxide transparent electrode of the present invention is tin oxide (51102) or tin oxide-indium oxide (I
T O = In2O3-9n02), and any of them can be used, but ITO has a lower specific resistance and is suitable for a light control body that requires a large area.

The electrolyte may be any material that can color or erase the color of the EC material of one display electrode, and solution-type, gel-type, or solid-type electrolytes containing cations such as protons or lithium ions can be used.

In particular, when a simple oxide transparent electrode is used as the counter electrode as described above, it is preferable to mix a transparent redox agent that causes a redox reaction, such as Lil, into the electrolyte. Even if the above-mentioned oxide transparent electrode having a small polarity is used as the counter electrode, a sufficiently practical response speed can be obtained as a light control body.

In addition, since the dimming body generally has a large area and is visible through transmission or reflection, the display electrode and the counter electrode may short due to contact, or the lower side may swell or be damaged when used upright. In order to prevent the electrolyte from scattering, it is preferable to form the electrolyte into a gel.

Examples of the material for the gel electrolyte solution include resins 1 that can be dissolved in organic solvents such as γ-butyrolactone (γ-BL), propylene carbonate, and butyl alcohol to form a gel.

It is a gel-like electrolyte solution containing urethane resin, acrylic acid resin, polyvinyl butyral resin, other resins, or copolymers thereof, and it is preferable to use a solution containing a redox agent, especially the L eye. However, it goes without saying that it is not limited to these.

In addition, solid electrolytes have the same effect as gel electrolytes, but they are not productive when used in large areas, and are easily damaged when bending force is applied due to wind or pressure, so they are not suitable for use as light control bodies. A gel electrolyte or a flexible film electrolyte impregnated with an electrolytic solution is preferable.

As for the sealing material, it is not necessarily necessary in the case of solid electrolyte, but it is preferable from the viewpoint of reliability, and adhesives or adhesive films such as epoxy resin, silicone resin, and fluororesin can be used. .

The terminals of the electrodes must be conductively connected to the outside so that a considerably larger current can flow than one display element. For this reason, it is preferable to provide a band-shaped low-resistance member on the side where the terminal is provided and take it out. Examples of this include electroless Xi plating, metal vapor deposition, conductive paste baking, and adhesion of metal foil on the transparent electrode. , glass solder, etc. may be used alone or in combination, and if necessary, lead pins may be attached.

The resistance of the electrode of the present invention may normally be 1.OMEGA.10 to 100 .OMEGA./mouth, but the lower the resistance, the more preferably the resistance is about 1 to 20 .OMEGA./mouth.

[Function] FIG. 2 is an explanatory diagram showing applied voltages for explaining the effects of driving according to the driving method of the present invention.

The left side of the figure shows the young color of the EC material (WO3);
The figure shows the period until the transmittance of llb reaches about 10%.

Since this coloring is performed using a constant current, the IT of the counter electrode
O applied voltage (VS.

The voltage applied to the reference electrode 5CE) 11 and the WOx mark on the display electrode (v s , 5CE) 12 indicates that the transmittance of WO3 on the display electrode 9 gradually increases.
%, the potential of +d03 is about -0.7
V (vs, 5CE).

Next, the color erasing process begins.

Here, if a constant voltage of 1.5 V is applied as the decoloring voltage, the ITO of the counter electrode has a -
A voltage of 1.5V is applied, and a voltage of -2.2V at which ITO is reduced is applied to SCH.

The right side of the figure shows the decoloring process of the EC material (WO3). This decoloring is carried out using a constant current, and a voltage higher than a certain voltage, for example 1.5V, is not applied. In this decoloring step, the ill pressure of the voltage (VS, 5CE) applied to the ITO of the counter electrode + 4 for the display electrode 03 gradually increases, but the potential 13 of the buttocks 03 for the SCH is low. Therefore, the potential of the ITO of the counter electrode with respect to the SCE increases slightly.

After that, when the erasure of w03 is almost finished,
The upper part of WCh with respect to SCH becomes almost OV, hardly changes, and it becomes difficult for current to flow. Therefore, since the constant current drive circuit tries to maintain the current value, the voltage applied between WO3 of one display electrode and 170 of the counter electrode increases rapidly.

Therefore, if a simple constant current drive is performed, a high voltage will be applied to the ITO of the counter electrode, causing reduction of the ITO. In addition, to prevent this, 7ft
If the decoloring process is stopped when the pressure becomes high, some residual color will remain.

However, in the driving method of the present invention, since a voltage higher than a certain voltage is not applied, the voltage applied between the display electrode 03 and the counter electrode 170 is 1.5
It cannot exceed V.

At this point, the potential of WO3 with respect to SCH has become extremely low, and the potential of ITO of the counter electrode with respect to SCH has become -
It will not exceed 1.8V.

However, if this voltage exceeds the reduction potential of ITO, or if it is used under bright light such as sunlight as mentioned above, this constant voltage should be lowered, for example 1.2 to 0. It is sufficient to set it to about .8V.

In the driving method of the present invention, even if the voltage E suddenly rises in constant current driving, a constant voltage is applied for a while, so that the color is sufficiently erased and there is no remaining color.

In the present invention, when the device is not driven after coloring and erasing one color, the power source may be disconnected and the device placed in a floating state.

In addition, as an application of the present invention, the Ml flow value of constant current drive may be switched in multiple stages, or the display electrode and the counter electrode may be short-circuited after decolorization by the drive of the present invention. Various applications are possible within the range that does not impair the effects of the present invention.

[Example] Example 1 30c meeting x 30c meeting x 3. I on the glass plate of Oms
TO was formed to a thickness of 2,000 layers to form a substrate with approximately 1,007 holes. Add 1103 to 8000 on this board
A display electrode substrate was prepared by manual vapor deposition, and this display electrode substrate and the above substrate were used as a counter electrode substrate, and the electrode surfaces were placed opposite each other, and 50% of a 0.75M Lil γ-butyrolactone solution was placed inside the dehydrated polyvinyl resin. Butyral 25g
A gel-like core in which the liquid was dissolved was sealed and sealed with an epoxy sealant. Incidentally, the electrodes of this single substrate were provided with strip-shaped metal leads at both ends to form a light control body having the same structure as that shown in FIG. 1.

The result of driving this light control body with constant current or constant voltage is the first
Shown in the table.

Note that the transmittance of w03 was set to 80% when decoloring, and the transmittance when colored was 10%. As is clear from this result, the driving method of the present invention does not cause the reduction of IT0.
The coloring/decoloring cycle life of the light control element was long.

Example 2 A light control body was manufactured in the same manner as in Example 1 except that a 10csX IOcmX 1.1-layer porcelain glass plate was used.

The result of driving this dimmer with constant current or constant voltage is the second
Shown in the table.

Note that the transmittance of 1w03 when decolored was 80%, and the transmittance when colored was 5%. As is clear from this result, the driving method of the present invention does not cause reduction of ITO.
The coloring/decoloring cycle life of the light control element was long.

m1 Table 2 Table 2 [Effects of the Invention] The driving method of the present invention can prevent the reduction of ITO, which is dangerous to occur when decoloring a light control body through which a large current flows, and does not generate bubbles. The life of the light control body can be extended without reducing its visibility. In particular, reduction of ITO due to an increase in applied voltage due to a decrease in response speed that occurs at low temperatures can be achieved without adding an extra circuit.

It can be prevented automatically.

Also, even if a large current is applied or a high coloring is applied, that is, even if the applied voltage tends to increase.

Since there is no need to worry about reduction of ITO, the transmittance for r1 color can be made quite low.

Furthermore, there is almost no residual fade that tends to occur with constant current driving, and the ratio of transmittance during coloring to that during decoloring can be increased.

The present invention is not limited to this example, and the substrate may be replaced with tempered glass or laminated glass, or the surface may include a non-glare layer, a heat ray absorption layer,
A line reflection layer or a single layer of ultraviolet cut filter may be formed, and various applications will be possible in the future.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the basic structure of a light control body according to the present invention. FIG. 2 is an explanatory diagram showing applied voltages in the driving method of the present invention. Substrate = 1, 4 Oxide transparent electrode = 2 GC material layer: 3 Counter electrode = 5 Electrolytic W: 6 ・・Riyame 4■S heaven

Claims (5)

[Claims] (1) A display electrode substrate having an electrochromic material layer formed on a transparent oxide electrode and a counter electrode substrate having a transparent oxide electrode are arranged so that the electrode surfaces face each other, and an electrolyte is sandwiched between these electrodes. A method for driving a light control body for coloring and decoloring a light control body with a constant current, characterized in that a negative voltage higher than a certain voltage is not applied to the oxide transparent electrode at least during color erasure. How to drive a light body. (2) The method for driving a light control body according to claim 1, wherein the oxide transparent electrode of the light control body is a light control body made of tin oxide-indium oxide. (3) The method for driving a light control body according to claim 1, wherein the oxide transparent electrode of the light control body is a light control body made of tin oxide. (4) The method for driving a light control body according to claim 1 or 2, wherein the counter electrode of the counter electrode substrate is a light control body consisting only of an oxide transparent electrode. (5) The method for driving a light control body according to claim 1, wherein the electrochromic substance is a light control body containing tungsten oxide as a main component.