JPS62265630A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To eliminate the decrease of coloration efficiency by electron conductivity and to obtain good responsiveness by escaping the leak current in a solid electrolyte by using a bypass electrode which does not react with ions. CONSTITUTION:The solid electrolyte film 2 is formed to cover a display film 1 and the electrode 3 consisting of an electrode active material is formed on the film 2 and further, the bypass electrode 5 consisting of an inert material is formed thereon. The electrodes 3, 4 are formed by electron beam vapor deposition. The electrode 3 is connected to the anode of a diode 72 and a power source 8 and the electrode 5 is connected to the cathode of the diode 72 and the cathode of a diode 71. A current conducting electrode 4 is connected to the anode of the diode 71 and the power source 8. The excess electrons tending to flow into the electrolyte film 2 by passing the display film 1 in the coloring stage of the display film 1 are attracted to the bypass electrode 5 and the blocking of the Ag<+> ions by the excess electrons is eliminated, by which the decrease of the coloration efficiency is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrochromic display device (ECD) K, and particularly to a display device using a solid electrolyte that selectively transports ions serving as a coloring source.

[Conventional technology]

The above ECD is provided with a transition metal oxide film for color development between current-carrying electrodes, and a dielectric or electrolyte for transferring ions thereto. ECDs that use electrolytes have been proposed, including those that use electrolytes and those that use solid electrolytes.

ECDs using the above-mentioned dielectric material have a dielectric material interposed between the electrodes) and operate at a high voltage, and since the substantial source of ion supply is moisture adsorbed in the dielectric material, when high voltage is applied, H! or Ox may be generated and the element may be damaged.

Electrolyte-type ECDs do not have this problem, but those that use electrolyte have a problem with the reliability of the seal structure against leakage.

Products that use solid electrolytes do not have the above-mentioned problems of element damage or liquid leakage, and their operating voltage is low, making them ideal for future ECs.
υ, β-Alz O, which is considered to be the mainstream of D
s, RbAga 6, Rb4CutsCgtm 2
, Nas Zrs -8it PO+t (NAS engineering C0
Various superionically conductive solid electrolytes such as NILis N, Li, and NILis have been developed.

[Problems to be solved by the invention] ECDs using solid electrolytes have excellent characteristics as described above.
However, there are still problems to be solved. This is because the electrolyte has not only ionic conductivity but also electronic conductivity to some extent, and due to such electronic conductivity, ions that should contribute to color development combine with electrons, resulting in a decrease in color development efficiency.

In view of these problems, the present invention has developed an E
An object of the present invention is to provide an ECD that does not have a decrease in coloring efficiency due to electronic conductivity and has excellent responsiveness.

[Means for solving problems]

To explain the structure of the present invention with reference to FIG. 1, there is provided a display membrane 1 and a solid electrolyte 2 that selectively transfers ions to produce color. A bypass electrode 5 is provided. The bypass electrode 5 does not react with the ions, and has the function of letting leakage current in the solid electrolyte 2 escape.

[action, effect]

When the solid electrolyte 2 side is used as a positive electrode, ions move from the electrolyte 2 into the display film 1, causing the display film 1 to develop color. At this time, since the solid electrolyte 2 has electronic conductivity, electrons flow into the mysolite 2 from the display film 1 serving as a negative electrode, combine with the ions, and reduce coloring efficiency.

Here, in the present invention, the electrons flowing into the bypass electrode 5VC are taken out from the bypass electrode 5 without being combined with the ions. Thus, the KCD of the present invention can maintain high coloring efficiency.

〔Example〕

FIG. 1 shows an example of an ECD according to the present invention.

A conductive transparent film such as a To film is formed on the entire surface of the glass substrate 6 to serve as one current-carrying electrode 4.

A W Os film is formed on the electrode 4 by electron beam evaporation to serve as the display film 1. This vapor deposition is 99.99%
WOs was used as the evaporation material, and the substrate temperature was 70-80℃.
℃, deposition rate 2-3 A/BeQ, Ganu pressure 1.0
The test was carried out while introducing 02 of X10Pa. The obtained W Os film is in an amorphous state, and the film thickness is about 3
000! It is.

A solid electrolyte membrane 2 is formed to cover the display membrane 1. The electrolyte membrane 2 is made of RbAg4, which is vacuum deposited by resistance heating. i.e. alumina coated tungsten boat IICRI)Ag
Step 4 Add powder and heat the boat by resistance to R1.
) A g a technology is evaporated. The substrate temperature at this time is 20~30''C1 vapor deposition rate is 4~5 A/8eQ.The obtained film thickness is 6000~8000 A.
bAg4S is obtained by vacuum-sealing the tube and heating it at 160° C. for 1 hour.

On the electrolyte membrane 2 is an electrode active material (Ag in this example).
The other electrode 3 is formed of a material such as the above-mentioned material, and the bypass electrode 5 is formed of an inert material (Au in this example). The inert substance refers to a substance that does not react with the ions (Ag in this example) in the electrolyte 2. Each of these electrodes 3
．． 5 is formed by electron beam evaporation, and the electrode 3 is connected to the anode of the diode 72 and the power source 8 by a copper lead wire fixed thereto with silver paste. [Pole 5 is connected to the cathode of the diode 72 and the cathode of the diode master 1 by a lead wire, and is connected to the cathode of the diode 72 and the cathode of the diode 1
is connected to the anode of the diode 71 and the power supply 8.

The diode 71.72 has a withstand voltage of about 30V, and a mechanical MF of about 300 to 500mA. For example, Toshiba 515
88 can be used. A wiring diagram of the ECD having the above structure is shown in FIG.

When the display film 1 is to be colored, the electrode 3 is set to a positive potential and the electrode 4 is set to a negative potential. At this time, diode 7
1 becomes non-conductive due to reverse bias, and diode 72 becomes conductive due to forward bias. This is shown in FIG. In the positive potential electrode 3, the constituent Ag emits electrons e and becomes Ag+ ions, which move through the solid electrolyte membrane 2 into the display membrane 1 and receive electrons e.
Forms WO5 tungsten bronze and develops color.

At this time, since the electrolyte 2 has electronic conductivity, surplus electrons Δe- flow through the display film 1. This surplus electron Δe- obstructs the flow of Ag+ ions and also
A from K to recombine with g”1 on into the display film 1
It prevents the movement of g+ ions, which reduces the color development efficiency.

Here, in the present invention, since the bypass electrode FM5 is provided, the surplus electrons Δe- are attracted in the direction of the electrode 5 and taken out therefrom.

Therefore, blocking of Ag ions due to surplus electrons Δe is eliminated, and a decrease in coloring efficiency is prevented.

Figure 4 shows the flow of electrons during decolorization. In this case, the diode 71 (FIG. 2) becomes conductive and the diode 72 remains non-conductive.

In the figure, if the surplus electrons △e are the bypass electrode 5, υ
The movement of Ag ions that are extracted and returned to the electrode 3 is not hindered. Thereby, decoloring can also be carried out efficiently.

An optical density change ΔOD defined by the following formula was employed as an index for evaluating the effects of the present invention.

ΔOD-10gOR-log Ro /R where, OR
is the contrast ratio, and Ro and R are the reflected light intensity when decoloring and when coloring, respectively.

ΔOD is originally proportional to the amount of injected charge Q. The inventors irradiated the entire area with white light using a tungsten lamp,
The above Ro%R was determined by receiving reflected light with a phototransistor.

Figure 5 shows the change in optical density Δ with respect to the amount of injected charge Q for the device of the present invention and a conventional device without a bypass electrode.
It shows the change in OD. In the figure, line X represents the present invention, and line y represents the conventional example. As is known from the figure, in the conventional example, when the amount of injected charge Q becomes 1 omC.am or more, the density change ΔOD becomes saturated. This is caused by the fact that the surplus electrons Δe- increase proportionally and the movement of Ag ions is obstructed.

On the other hand, in the present invention, Ag due to the surplus electron Δe is
Since ion blocking does not occur, the above density change Δ
As the charge amount Q increases, the OD increases without being saturated.

Thus, the ECD of the present invention maintains high coloring efficiency even when the injected charge flQ is increased.

Also, the fact that the amount of injected charge Q can be increased means that
This means that the oxidation-reduction reaction can be accelerated and the responsiveness can be improved without any modification, and therefore better display responsiveness can be obtained by making the operating voltage relatively high.

In the above embodiment, the bypass electrode 5 is made of P in addition to Au.
In addition, conductive ceramics with low resistance may also be used.

Further, as the display film, for example, a Moos film can be used in addition to WOsOs. Of course, other superionic conductors such as KAg4-1 can be used as the solid electrolyte.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the element structure of the present invention, Fig. 2 is a wiring diagram of the element, Figs. 3 and 4 are diagrams explaining the operation of the element, and Fig. 5 is a diagram of optical density change characteristics of the element. . 1...-Display film 2--Solid electrolyte chamber 5.4...-Electrifying electrode 5--Bypass electrode 6--Glass substrate 71,'F 2--Diode 8--Power supply Figure 1 Figure 2 Figure 3 tJe lJe- 1g5 Figure

Claims (5)

[Claims] (1) In an electrochromic display element comprising a display film and a solid electrolyte that selectively transfers ions that serve as a coloring source to the display film, a bypass electrode made of an inert substance that does not react with the ions is attached to the solid electrolyte. An electrochromic display element, characterized in that the bypass electrode is disposed in contact with the solid electrolyte to allow leakage current in the solid electrolyte to escape from the bypass electrode. (2) The electrochromic display element according to claim 1, wherein the solid electrolyte is made of a silver ion conductor, and the bypass electrode is made of Au or Pt. (3) The electrochromic display element according to claim 2, wherein a current-carrying electrode is provided in contact with the solid electrolyte, and the current-carrying electrode is made of Ag. (4) The electrochromic display element according to claim 1, wherein the display film is formed of a WO_3 film, a current-carrying electrode is provided in contact with the display film, and the current-carrying electrode is formed of a transparent conductive film. (5) providing the display film and the solid electrolyte between the current-carrying electrodes;
The electrochromic display element according to claim 1, wherein the bypass electrode is provided between the electrode and each of the current-carrying electrodes and connected to each of the current-carrying electrodes via a diode with a cathode facing the bypass electrode. .