Optical control circuit for electrochromic layers

  • US 4,529,873 A
  • Filed: 10/15/1982
  • Issued: 07/16/1985
  • Est. Priority Date: 10/29/1981
  • Status: Expired due to Fees
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First Claim
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1. Apparatus for variable charge control of an electrochromic layer, said layer being uncolored for the case of no charge in said layer and being colored to a progressively increasing state of coloration for progressively increasing charges in said layer, said apparatus comprising:

  • a light source and a photoelectric receiver positioned to locally expose a portion of said electrochromic layer to a predetermined quantum of light from said source and to produce an electrical output signal in response to that fraction of said quantum as is passed at least once through said layer, whereby said electrical signal is a measure of the instantaneous colored state of said layer;

    a charging circuit connected to charge said layer, a charge-removal circuit connected to remove charge from said layer, guide-value means establishing a guide-value signal, and a controller having a connection to said guide-value means and a connection to the output of said receiver, said controller being connected to control charging-circuit operation for a detected receiver-output signal of predetermined excess with respect to the guide-value signal and to control operation of said charge-removal circuit for a detected receiver-output signal of predetermined deficiency with respect to the guide-value signal;

    said guide-value means being continuously variable between upper and lower limits of guide-value signal corresponding to predetermined limits of charge application to and of charge removal from said layer, and said guide-value means including an optical sensor responsive to brightness independent of transmission through said layer and being operative to produce a brightness-responsive guide-value signal which is within said predetermined limits.

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