Automatic rearview mirror for automotive vehicles

  • US 4,443,057 A
  • Filed: 06/01/1981
  • Issued: 04/17/1984
  • Est. Priority Date: 06/01/1981
  • Status: Expired due to Term
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First Claim
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1. In a rearview mirror for an automotive vehicle, the combination including a reflective element having a full reflectance mode and a partial reflectance mode, forward facing sensor means effective to detect light forwardly of the vehicle and generate a corresponding forward electrical signal indicative of the forward light level, backward facing sensor means effective to detect light rearwardly of the vehicle and generate a corresponding rearward electrical signal indicative of the rearward light level, forward sensor filtering means characterized by having a first time response and having a smoothing time averaging effect on the forward electrical signal and acting on the forward electrical signal to produce a filtered forward electrical signal independent of the rearward electrical signal, a rearward circuit having an input connected to said backward facing sensor means and an output, and means operable to change said reflective element between said full reflectance mode and said partial reflectance mode as a function of the output of said rearward circuit and filtered forward electrical signal, the functional time response provided by said forward sensor filtering means being slower than the functional time response provided by said rearward circuit.

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