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Electronic control system for automatic rearview mirrors for automotive vehicles

  • US 4,580,875 A
  • Filed: 03/30/1984
  • Issued: 04/08/1986
  • Est. Priority Date: 03/30/1984
  • Status: Expired due to Fees
First Claim
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1. A control system for an automatic rearview mirror for an automotive vehicle, said automatic rearview mirror 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, 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 the filtered forward electrical signal, the functional time response provided by said forward facing sensor filtering means being slower than the functional time response provided by said rearward circuit, and means effective to reduce the sensitivity of the mirror as a function of the recent activity of said reflective element.

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