Patent ID: 8018644

Claim:
A method of controlling transmittance of an electrochromic device having a first electron conducting layer and a second electron conducting layer, a first electrochromic layer at least partially covering said first electron conducting layer, a counter electrode layer at least partially covering said second electron conducting layer and an electrolyte layer laminated between and at least partially covering said first electrochromic layer and said counter electrode layer, said method comprising the step of: applying a sequence of voltage pulses between said first and second electron conducting layers; said step of applying further comprises providing an open circuit between said first and second electron conducting layers between periods of applied voltage; measuring at least one value of a voltage between said first and second electron conducting layers over said first electrochromic layer, said electrolyte layer and said counter electrode layer during a period of said open circuit, after relaxation of ohmic losses in said first electrochromic layer, said electrolyte layer and said counter electrode layer; and controlling an applied pulse voltage dependent on said measured at least one voltage value.