Patent ID: 7205524

Claim:
A rearview mirror system for a vehicle, said rearview mirror system comprising: an electro-optic reflective element; an ambient light sensor that is operable to sense ambient light; a glare light sensor that is operable to sense glare-producing light; and a circuit that is responsive to said ambient and glare light sensors and which produces an output that establishes a reflectance level of said reflective element, said circuit comprising a charge accumulation device, a comparison function and a controller, said comparison function comparing an output of said charge accumulation device with a reference, said controller selectively connecting said glare sensor and said ambient light sensor with said charge accumulation device such that said controller connects said glare sensor with said charge accumulation device at a time when said ambient light sensor is not connected with said charge accumulation device and said controller connects said ambient light sensor with said charge accumulation device at a time when said glare sensor is not connected with said charge accumulation device, wherein said controller establishes glare and ambient light levels and thereby the reflectance level of said reflective element as a function of the time for said output of said accumulation device to reach said reference.