Electrochromic device

• US 4,726,664 A
• Filed: 03/24/1986
• Issued: 02/23/1988
• Est. Priority Date: 03/25/1985
• Status: Expired due to Fees

• Current Assignee: Nippon Sheet Glass Company Limited
• Original Assignee: Nippon Sheet Glass Company Limited
• Inventors: Kawahara, Hideo, Tada, Hiroaki, Nagayama, Hirotsugu
• Primary Examiner(s): Lovering, Richard D.
• Assistant Examiner(s): Kilby, Catherine S.
• Application Number:
  US06/843,002
• Time in Patent Office: 701 Days
• Field of Search: 252/600, 252/582, 350/357
• US Class Current: 359/275
• CPC Class Codes: G02F 1/1516 comprising organic material
• CPC Class Codes: G02F 1/1523 comprising inorganic material
• CPC Class Codes: G02F 1/1524 Transition metal compounds
• CPC Class Codes: G02F 2001/1517 Cyano complex compounds, e.g. Prussian blue
• CPC Class Codes: G02F 2001/1557 Side by side arrangements of working and counter electrodes

Abstract

An electrochromic device comprising an oxidation coloring substance coloring in an oxidized state and a reduction coloring substance coloring in a reduced state which are formed on the surfaces of a pair of electrodes, respectively, and an electrolyte held between the two substances, wherein the oxidation coloring substance is a double salt containing an iron hexacyanoferrate and the reduction coloring substance is a tungsten-oxalic acid compound. The electrochromic device has a long life suitable for actual applications and a short response time and can operate at low applied voltages.

Claims

1. An electrochromic device comprising an oxidation coloring substance coloring in an oxidized state and a reduction coloring substance coloring in a reduced state which are formed on the surfaces of a pair of electrodes, respectively, and an electrolyte held between the oxidation and reduction coloring substances, wherein the oxidation coloring substance is a double salt containing an iron hexacyanoferrate and the reduction coloring substance is a tungsten-oxalic acid compound.

2. An electrochromic devide according to claim 1, wherein the tungsten-oxalic acid compound contains oxalic acid coordinating with tungsten, the weight of said oxalic acid being 0.172 to 0.48 times the weight of the tungsten in the tungsten-oxalic acid compound.

3. An electrochromic device according to claim 1 or 2, wherein the electrolyte contains at least one cation species selected from the group consisting of potassium ion, rubidium ion, cesium ion and ammonium ion.