United States Patent  [ii] Patent Number: 5,076,673
Lynam et al.  Date of Patent: Dec. 31, 1991
 PROLONGED COLORATION
 Inventors: Nial) R. Lynam, Holland; Kenneth L.
Schierbeek, Zeeland, both of Mich.
 Assignee: Donnelly Corporation, Holland, Mich.
 Appl. No.: 565,660
 Filed: Aug. 10, 1990
 Int. CI.' G02F 1/01
 U.S. CI 359/271; 359/275;
 Field of Search 350/357, 355
 References Cited
U.S. PATENT DOCUMENTS
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FOREIGN PATENT DOCUMENTS
240226 3/1987 European Pal. Off. .
285724 12/1987 European Pat. Off. .
"Electrochromism of Organic Compounds II. Spectral and Electrochemical Examination of a System based on Methyl viologen and 5,10-Dihydro-5,10-Dimethyl
An electrochromic assembly useful for rearview mirrors, windows, vehicle sunroofs, information displays, office partitions and other structures which allows prolonged coloration substantially indefinitely without voltage or concentration gradient induced color segregation. The assembly includes a pair of optically aligned, electrochromic devices defined by at least one transparent sheet, first and second layers of electrochromic material adjacent opposing surfaces of the sheet, the transmittance of said layers being variable when an electrical field is applied, and electrical conductors for applying such an electrical field. Electrical energy is switched alternately from one device to the other for short periods of time while the remaining device is alternately bleached. The switching can continue cyclically for any desired period. A reflective coating may be included to allow operation as a dimming mirror. Anti-reflection and index of refraction matching coatings may be included to enhance transmission. Electrical energy may also be applied to both devices simultaneously to provide a deeper level of coloration than is possible from either device alone.
51 Claims, 7 Drawing Sheets