All solid-state complementary electrochromic display device

• US 4,459,035 A
• Filed: 12/10/1982
• Issued: 07/10/1984
• Est. Priority Date: 12/28/1981
• Status: Expired due to Fees

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Hashimoto, Eigo, Nanya, Takanori
• Primary Examiner(s): Roskoski, Bernard
• Application Number:
  US06/448,711
• Time in Patent Office: 578 Days
• Field of Search: 350/357, 368/239, 368/241, 368/242, 340/763, 340/785, 340/812
• US Class Current: 368/241
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor

Abstract

EC display device suitable for drive by means of a charge transfer method which is one of the methods for realizing a constant charge drive, in which all the members comprise solid materials only and a reduction coloration type EC material and an oxidation coloration type EC material are combined. The device has means for applying a voltage between each of the EC segments, with the counter electrode shut off, and a fixed quantity of electric charge is transferred from one EC segment to another. The counter EC layer provided on the counter electrode functions as a donnor or an acceptor of protons so as to activate the EC reactions and this counter layer is colored or bleached by itself, producing double contrast of the display.

Claims

1. An EC display device comprising:

a transparent substrate;

a plurality of transparent segmented electrodes formed on a surface of said transparent substrate;

EC segments formed on said transparent segmented electrodes, said EC segments being formed of one of an oxidation coloration type EC material and a reduction coloration type EC material;

a counter EC layer positioned apart opposite to said EC segments, said counter EC layer being formed of the other of the oxidation type EC material and the reduction coloration type EC material;

an ion permeable solid insulating layer interposed between said EC segments and said counter EC layer;

a counter electrode provided outside said counter EC layer;

first means for applying direct current voltage across said counter EC layer and said transparent segmented electrodes; and

second means for applying direct current voltage between each of said transparent segmented electrodes;

whereby said first means apply the direct current voltage across said counter electrode and a part of said transparent segmented electrodes so that the corresponding part of the EC segments and a part of the counter EC layer positioned opposite are colored and then said second means apply the direct current voltage between a colorless EC segment to be colored and a colored EC segment to be bleached through each of said transparent segmented electrodes so that electric charge injected in said colored EC segment is transferred to said colorless EC segment through said counter EC layer so as to provide a display.

2. The display device according to claim 1 wherein said oxidation coloration type EC material is iridium hydroxide [Ir(OH)n] and said reduction coloration type EC material is tungsten trioxide (WO₃).

3. The display device according to claim 1 wherein said ion permeable solid insulating layer is tantalum oxide (Ta₂ O₅).

4. The display device according to claim 1 wherein said counter EC layer is divided into a plurality of parts so as to form the same pattern as that of said EC segments.

5. The display device according to claim 1 wherein said counter EC layer is a continuous layer covering all the EC segments.

6. The display device according to claim 1 wherein all the EC segments are of the same area.

7. The display device according to claim 1 wherein said EC segments are divided into display EC segments comprising seven segments arrayed in the form of numeral eight and a plurality of support EC segments arrayed near said display EC segments.

8. An electronic timepiece having a display device comprising:

a transparent substrate;

a plurality of transparent segmented electrodes formed on a surface of said transparent substrate;

EC segments formed on said transparent segmented electrodes, said EC segments being formed of one of an oxidation coloration type EC material and a reduction coloration type EC material;

a counter EC layer positioned apart opposite to said EC segments, said counter EC layer being formed of the other of the oxidation coloration type EC material and the reduction coloration type EC material;

an ion permeable solid insulating layer interposed between said EC segments and said counter EC layer;

a counter electrode provided outside said counter EC layer;

first means for applying direct current coltage across said counter layer and said transparent segmented electrodes; and

second means for applying direct current voltage between each of said transparent segmented electrodes;

whereby said first means apply the direct current voltage across said counter electrode and a part of said transparent segmented electrodes so that the corresponding part of the EC segments and a part of the counter EC layer positioned opposite are colored and then the second means apply the direct current voltage between a colorless EC segment to be colored and a colored EC segment to be bleached through each of said transparent segmented electrode so that electric charge injected in said colored EC segment is transferred to said colorless EC segment through said counter EC layer so as to provide a display.

9. The electronic timepiece according to claim 8 further comprising a display device, said display device displaying time by the application of the direct current voltage between said segmented electrodes and said counter EC layer.