Continuous charge control for electrochromic layers

US4529275A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventor

• Horst Ballmer · Heidenheim, DE

Key dates

• Filing date: Oct 22, 1982
• Grant date: Jul 16, 1985
• Expiry date: Oct 22, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/163
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A continuous change in color is provided in order to control the absorptance of an electrochromic layer. The quantities of charge to be fed and removed by two sources of constant current are measured with a forward/backward counter. For decoloring processes, smaller amounts of charge are removed from the layer than are supplied to it for corresponding coloring processes. The quantities of charge removal for decoloring processes are, however, slightly greater than the quantities of charge which are theoretically necessary to obtain intermediate values with exactly the same absorptance, thereby assuring against destruction of the layer, even in case of numerous changes between different colorings. Preferred fields of use are lenses, particularly eyeglass lenses, filters and dimmable mirrors, using an applied electrochromic layer whose absorptance is varied.