JPS58105127A - Electrochromic display - Google Patents

Abstract

PURPOSE:To eliminate the exfoliation of a counter electrode and to improve response characteristics by constituting the counter electrode of a calcined film consisting of active material powder and glass frit binders thereby improving workability and making the display suitable for mass production. CONSTITUTION:Lead electrodes 14 consisting of a conductive film are formed on the inside surface of a glass substrate 4 of a tray shape, and the paste prepd. by mixing a powder mixture of 20 parts lead glass frit and 80 parts tungsten powder as an active material with nitrocellulose is coated therein and is calcined in air for 1hr at 350 deg.C, and is further calcined in a hydrogen atmosphere for 30min at 550 deg.C, whereby a counter electrode 15 is formed. Display electrodes 3 are formed on the lead electrode 2 provided on a substrate 1. A light scattering plate is disposed between both substrates 1 and 4, and an electrolyte is sealed therebetween; thereafter, the substrates are stuck by means of an adhesive agent 6. Fe, Nb, Ti, Mo, Ir, Sn, Pb, etc. and oxides of these metals are usable as the active materials.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrochromic display device (hereinafter referred to as ROD) using a transition metal oxide such as tungsten oxide (Tf03) as a display material.

Conventionally, an ECD using a transition metal oxide such as WO3 as a display material has a structure as shown in FIG. In FIG. 1, 1 is a transparent substrate such as a glass plate on which a transparent lead electrode 2 made of ITO or the like is formed on the inner surface, and 3 is a display electrode constructed by forming a coloring layer of WO5 in a desired pattern. and is formed on the lead electrode 2. Reference numeral 4 denotes a dish-shaped base material made of ceramic, glass, etc., with a counter electrode 6 made of pressure-molded carbon formed on the inner bottom surface so as to face the display electrode 3. This base material 4 is sealed together with the substrate 1. The edge of the opening is fixed to the substrate 1 with an adhesive 6 so as to form a space.

In the sealed space formed by the base material 4 and the substrate 1, an electrolytic solution 7 is sealed, and a light beam made of A/203 is interposed between the display electrode 3 and the counter electrode 6. A reflecting plate 8 is provided.

9 is an injection port for the electrolytic solution 7, into which the electrolytic solution 7 is injected. Further, this lead electrode 10Vi is attached to the base material 4.
It is passed through and fixed with adhesive 11 and pulled out to the outside.

In such an ECU, between the display electrode 3 and the counter electrode 5,
When a constant voltage is applied to the display electrode 3 as a negative electrode, color develops,
Erasing is performed by applying a reverse bias.

However, in the case of this flexible ECD, since the counter electrode 6 is formed by pressure molding carbon, there is a drawback that the workability of the pressure molding process is poor.

An ECD having the structure shown in FIG. 2 has been considered as an ECD that overcomes these drawbacks. In the case shown in FIG. 2, a counter electrode 13 is formed by coating an active material, carbon powder, and an organic binder in a base or liquid state on a lead electrode 12 made of Au provided by vapor deposition. . As the binder, organic polymer substances such as Evochishi resin, phenol resin, and silicone resin are used.

However, in the case of such ECD, since the active substance and carbon powder are covered with a binder, the activity of the active substance decreases, and the resistance at the interface of the carbon powder increases, resulting in a slow response speed for coloring and erasing. It had the following drawback. Further, the organic binder deteriorates due to the organic electrolyte mainly composed of propylene carbonate, and there is a problem in that the counter electrode 5 peels off from the lead electrode 12 especially during high-temperature storage.

The present invention solves these conventional drawbacks; it is stable against organic electrolytes, has a fast response speed for color development and erasing, and
It also provides a highly productive gcn.

In the present invention, the counter electrode is constituted by a fired film made of active material powder and a glass frit type binder. Hereinafter, l<CD according to the present invention will be explained using specific examples.

FIG. 3 shows an ECD-1z according to an embodiment of the present invention, and in FIG. 3, the same parts as in FIG. 1 are designated by the same numbers.

In FIG. 3, a lead electrode 14 made of a conductive film of *u, In2O5, Ti, etc. is formed by vapor deposition on the inner surface of a base material 4 made of a dish-shaped glass substrate.

On the lead electrode 14, a mixed powder of 20 parts of lead-based glass frit and tungsten powder (more than 200 mesonyo) as an active substance was applied with pastera mixed with nitrocellulose, and then heated in air at 360°C for 1 hour. The counter electrode 16 is formed by firing and further firing in a hydrogen atmosphere at 550''C for 30 minutes.The display electrode 3 is formed on a transparent lead electrode 2 made of ITO provided on a substrate 1 made of a glass substrate. A/203
A fired plate or TlO2 porous polymer sort' (r) is used. Also, as the electrolytic solution 7, a liquid obtained by dissolving LiB1'4 as a branch salt in propylene carbonate is used, and vacuum impregnation is carried out through the injection port 9.

In the ECD of the present invention constructed as described above, when a constant voltage e is applied between the IJ-dead electrode 2 and the lead electrode 14, the active substance and the carbon powder' as well as epoxy, silicon and phenol The response speed for coloring and erasing was several times faster than when using a counter electrode made of a binder of organic polymeric material such as resin. Compared to the conventional ECD shown in Fig. 1, when forming the counter electrode 15, the counter electrode 16 can be formed by simply applying a paste and firing, which is advantageous for mass production. There is also less deterioration such as electrolyte leakage due to temperature changes.

Here, tungsten oxide is used as the active substance, and a mixed powder of carbon powder and glass frit powder is dispersed in nitrocellulose to create a paste, and the paste is applied onto the lead electrode 14 in the same manner as in the previous example. Yes, 500~
The counter electrode 16 was formed by firing at 600° C., and an ECD was assembled in the same manner as in the above embodiment, and as a result, the same effects as in the above embodiment were obtained.

F8. Nb, Ti.

Mo, Ir, Sn, Pb, Mn, V, Bi
, Cu, Pju, Ni.

Similar effects were obtained using a mixture of two or more selected from In and oxides of these metals. Moreover, when metal powder is used, by changing the composition of the atmospheric gas (02, N2°N2) during the firing conditions for one hour, a mixed powder with metal powder in an oxidized state can be obtained, and it has a stable potential. A counter electrode 16 is obtained. Further, when using only a metal oxide, mixing carbon powder when firing in an air atmosphere lowers the specific resistance of the counter electrode 16, resulting in a product with good response speed.

At this time, by firing in a hydrogen atmosphere, a mixed powder with a metal state can be obtained, and the specific resistance of the counter electrode 15 can be lowered as described above.

Further, glass frit type binders include lead type, zinc type, 5iOz type, etc., and are not particularly limited. Furthermore, graphite, carbon, expanded carbon, etc. can be used as carbon powder. Furthermore, the lead electrode 14 and the counter electrode 16 may be made of the same material.

As described above, T! of the present invention! , C: According to D, the counter electrode is formed by coating and firing a mixed paste of active material powder and glass frit type binder, and it is not only easy to work with and suitable for mass production. Unlike conventional organic binders, peeling of the counter electrode does not occur, and the response characteristics can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional electrochromic display device, FIG. 2 is a sectional view showing another conventional electrochromic display device, and FIG. 3 is an electrochromic display device according to an embodiment of the present invention. This is a cross-sectional view showing. 1...Substrate, 3...Display electrode, 4...
... Base material, 7 ... Electrolyte, 15 ...
Opposite. Name of agent: Patent attorney Toshio Nakao and 1 other person - Haha

Claims (2)

[Claims] (1) Consisting of a display electrode provided on a transparent substrate, a counter electrode provided on the base material to face the display electrode, and an electrolyte sealed between the display electrode and the counter electrode, and the counter electrode An electrochromic display device is composed of a fired film consisting of an active substance powder and a glass frit binder. (2) Active substance powder is Fe, Nb, Ti, W, Mo, I
r. Sn, Pb, Mn, V, Bi, Cu, Ru, Ni, In
The electrochromic display device according to claim 1, wherein the electrochromic display device is at least one selected from oxides of these metals.