Additional electrode of electrochromic display and refreshing method for the same

Abstract

An additional electrode is provided for developing a secondary electrochromic phenomenon on a counter electrode apart from the major electrochromic phenomenon which is developed between one or more display electrodes and the counter electrode. Current flows from an additional electrode to the counter electrode in developing the secondary electrochromic phenomenon. Coloration of the counter electrode, where the magnitude of an overvoltage of the counter electrode is small is stabilized to thereby enhance electronic properties of the electrochromic display. The material of the additional electrode is selected from metals having an appropriate ionization tendency with respect to an electrolyte, such as Mg, Al, Zn, Cr, Fe, Ni, Sn, and Pb, or a combination thereof. Otherwise, the material of the additional electrode is selected to be an inert material with respect to the electrolyte such as Ag, Au, Pt, Pd, In.sub.2 O.sub.3, and SnO.sub.2 or a combination thereof. The combination which is composed of both the appropriate ionization tendency metals and the inert metals can be available for the additional electrode. The electrochromic display can be controlled under one of several groups of driving techniques consisting of a potentiostatic driving, a constant current driving, and a constant voltage driving method.

Dependencies are inferred from the claim text.