Control circuit for an automatic rearview mirror

  • US 4,886,960 A
  • Filed: 04/05/1988
  • Issued: 12/12/1989
  • Est. Priority Date: 04/08/1987
  • Status: Expired due to Fees
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First Claim
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1. An automatic rearview mirror system for a vehicle comprising:

  • a reflective element actuatable between at least two different reflective conditions;

    a forward light sensor means for sensing light in a direction other than rearward of the mirror;

    a rear light sensor means for sensing light rearward of the mirror; and

    control circuit means for causing the reflective element to assume a reflective condition as a function of at least the output of said forward and rear light sensor means, said control circuit including modulation means for modifying the output of said forward light sensor means to produce a modified forward light signal and comparison means responsive to the output of said rear light sensor means and said modified forward light signal for indicating the desired reflectance condition of said reflective element as a function of said output of said rear light sensor and said modified forward light signal, wherein said modulation means modifies the output of said forward light sensor means in a manner that reduces the sensitivity of said control means to light rearward of the mirror.

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