Vehicle rearview mirror system having a variable reflectance control

A rearview mirror system for a vehicle, said rearview mirror system comprising:

• a variable reflectance transflective electro-optic reflective element, said transflective reflective element comprising a mirror reflector that partially reflects light incident thereon and that partially transmits light incident thereon;
• an ambient light sensor operable to sense ambient light, wherein said ambient light sensor comprises a silicon photo sensor comprising one of a photo-transistor and a photo-diode;
• a glare light sensor operable to sense glare-producing light incident at or near said reflective element, wherein said glare light sensor comprises a silicon photo sensor comprising one of a photo-transistor and a photo-diode;
• wherein each of said glare light sensor and said ambient light sensor comprises at least one of (a) a light-to-frequency converter that comprises the combination of a silicon photodiode and a current-to-frequency converter on a single monolithic CMOS integrated circuit and (b) a photo sensor that converts incident light to a digital signal capable of direct feed into a microprocessor;
• a video display screen disposed behind said transflective electro-optic reflective element and operable to display video information through said reflective element and viewable through said mirror reflector of said transflective electro-optic reflective element by a driver of the vehicle when said video display screen is activated, and substantially non-viewable by the driver of the vehicle when said video display screen is not activated;
• a display intensity control for adjusting a display intensity of said video display screen, said display intensity control adjusting the display intensity responsive to a brightness level of the scene sensed by at least one of said glare light sensor and said ambient light sensor, said video display screen having an operating range comprising a display intensity, as viewed by the driver of the vehicle when viewing said reflective element assembly as normally mounted in the vehicle, between zero candelas/square meter when said video display screen is not activated, and at least 400 candelas/square meter when said video display screen is activated;
• and
• wherein said display intensity adjustment is a function of at least one of (a) an ambient light level and (b) a glare light level representative of light impinging a rearward facing surface of said reflective element.

A rearview mirror system for a vehicle, said rearview mirror system comprising:

• a variable reflectance transflective electro-optic reflective element, said transflective reflective element comprising a mirror reflector that partially reflects light incident thereon and that partially transmits light incident thereon;
• an ambient light sensor operable to sense ambient light;
• a glare light sensor operable to sense glare-producing light incident at or near said reflective element;
• wherein said ambient light sensor comprises a silicon photo sensor and wherein said glare light sensor comprises a silicon photo sensor;
• wherein each of said glare light sensor and said ambient light sensor comprises at least one of (a) a light-to-frequency converter that comprises the combination of a silicon photodiode and a current-to-frequency converter on a single monolithic CMOS integrated circuit and (b) a photo sensor that converts incident light to a digital signal capable of direct feed into a microprocessor;
• a video display screen disposed behind said transflective electro-optic reflective element and operable to display video information through said reflective element and viewable through said mirror reflector of said transflective electro-optic reflective element by a driver of the vehicle when said video display screen is activated, and substantially non-viewable by the driver of the vehicle when said video display screen is not activated;
• a display intensity control for adjusting a display intensity of said video display screen, said display intensity control adjusting the display intensity responsive to a brightness level of the scene sensed by at least one of said glare light sensor and said ambient light sensor, said video display screen having an operating range comprising a display intensity, as viewed by the driver of the vehicle when viewing said reflective element assembly as normally mounted in the vehicle, between zero candelas/square meter when said video display screen is not activated, and at least 400 candelas/square meter when said video display screen is activated;
• wherein said display intensity adjustment is a function of at least one of (a) an ambient light level and (b) a glare light level representative of light impinging a rearward facing surface of said reflective element;
• and
• a temperature compensation function for compensating said reflectance level for temperature variation of at least one of said glare and ambient light sensors and wherein said temperature compensation comprises at least one chosen from a reference sensor that is not exposed to light and a temperature sensor.