An electrochromic display device has an electrolyte contained between two spaced-apart substrates. A plurality of display segments are disposed on the surface of at least one of the substrates in contact with the electrolyte, and a counter electrode is disposed on the surface of the other substrate in...http://www.google.de/patents/US4479121?utm_source=gb-gplus-sharePatent US4479121 - Electrochromic display device having constant color density and driving method therefor
