Electrochromic device for controlling transmittance of light

• US 4,958,917 A
• Filed: 01/23/1989
• Issued: 09/25/1990
• Est. Priority Date: 01/29/1988
• Status: Expired due to Fees

• Current Assignee: Central Glass Company Limited
• Original Assignee: Central Glass Company Limited
• Inventors: Hashimoto, Chikara, Inaba, Hiroshi, Nakase, Kiyoshi, Yanagida, Yukitoshi
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Shingleton, Michael B.
• Application Number:
  US07/299,418
• Time in Patent Office: 610 Days
• Field of Search: 350/357
• US Class Current: 359/275
• CPC Class Codes: G02F 1/153 Constructional details

Abstract

The invention relates to an electrochromic (EC) device for controlling transmittance of light, such as a window pane or a filter for a display. The EC device has a double-decker structure produced by superposition of two identical EC cells each having two oppositely arranged EC electrodes one of which is formed of a first EC material that takes on color in oxidized state, such as Prussian blue, and the other of a second EC material that takes on color in reduced state such as WO₃. The EC device has a transparent inner substrate with an EC electrode layer using one of the first and second EC materials on each side thereof and two transparent outer substrates each with an EC electrode layer using the other of the first and second EC materials. There is a peripheral seal between the inner substrate and each outer substrate, and the space defined between the inner substrate and each outer substrate is filled up with an electrolyte liquid. To minimize the number of leads for application of voltages to the four EC electrode layers, the EC electrode layers on the both sides of the inner substrate are connected with each other by an angled strip of a sheet metal fitted on the inner substrate, and the EC electrode layers on the outer substrates are connected with each other by another angled strip of a sheet metal fitted into a marginal region of the space between the two outer substrates.

Claims

1. An electrochromic device for controlling transmittance of light, comprising:

a transparent inner substrate with a transparent electrode layer coated on each side thereof;

first and second electrochromic layers which are formed on the electrode layers on the two opposite sides of said inner substrate, respectively, and are formed of one of a first electrochromic material which takes on a characteristic color in its electrochemically oxidized state and a second electrochromic material which takes on a characteristic color in its electrochemically reduced state;

a transparent first outer substrate which is coated with a transparent electrode layer and is arranged opposite to and spaced from said inner substrate such that the electrode layer of the outer substrate faces the first electrochromic layer, the outer substrate being dimensioned larger than said inner substrate;

a transparent second outer substrate which is coated with a transparent electrode layer and is arranged opposite to and spaced from said inner substrate such that the electrode layer of the second outer substrate faces the second electrochromic layer, the second outer substrate being dimensioned larger than said inner substrate;

third and fourth electrochromic layers which are formed on said electrode layer on said first outer substrate and said electrode layer on said second outer substrate, respectively, and are formed of the other of said first and second electrochromic materials;

a first peripheral seal formed of a butyl rubber base adhesive composition disposed in the space between the inner substrate and each of the first and second outer substrates so as to hold the inner substrate and the first and second outer substrates in the opposite and spaced arrangement and airtightly define a first space between the inner substrate and the first outer substrate and a second space between the inner substrate and the second outer substrate and forming a peripheral gap between the first and second outer substrates, a peripheral region of the inner substrate protruding into said peripheral gap;

an electrolyte liquid which fills up said first space and said second space;

a first connector which is an angled strip of a sheet metal having two parallel leg portions and is fitted on said inner substrate such that said two parallel legs are respectively fixed to the transparent electrode layers on the two opposite sides of said inner substrate;

a second connector which is an angled strip of a sheet metal having two parallel leg portions and is fitted into a marginal region of the space between said first and second outer substrates such that said two parallel leg portions are respectively fixed to the transparent electrode layer on said first outer substrate and the transparent electrode layer on said second outer substrate;

a second seal formed of polysulfide rubber filling said peripheral gap such that said first connector and at least said leg portions of said second connector are embedded in the second seal;

a first lead which extends outward from said first connector through said first and second seals; and

a second lead which extends outward from said second connector.

2. A device according to claim 1, wherein each of said sheet metal of said first connector and said sheet metal of said second connector is resilient.

3. A device according to claim 1, further comprising a first auxiliary electrode which is disposed in a marginal region of said first space and is insulated from the transparent electrode layers on said inner substrate and said first outer substrate, a second auxiliary electrode which is disposed in a marginal region of said second space and is insulated from the transparent electrode layers of said inner substrate and said second outer substrate, a thin conductor which connects said first and second auxiliary electrodes with each other through said first and second seals, and a third lead which extends outward from said thin conductor.