Electrochromic element driver with negative output resistance

  • US 6,222,177 B1
  • Filed: 01/19/1999
  • Issued: 04/24/2001
  • Est. Priority Date: 01/19/1999
  • Status: Expired due to Term
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First Claim
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1. A control arrangement for controlling an electrochromic element, the control arrangement comprising:

  • a drive circuit, configured and arranged to selectively apply a drive voltage across the electrochromic element in response to at least one of a glare signal and an ambient light level, the drive circuit being characterized by a negative output resistance;

    a feedback arrangement, integral with the drive circuit and configured and arranged to vary the drive voltage as a function of current draw in the electrochromic element; and

    at least one light sensor arrangement, configured and arranged to detect the ambient light level and to provide an indication thereof to the drive circuit whereby the drive voltage will increase at higher element temperatures and decrease at lower element temperatures.

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