According to one embodiment of the present invention, an electrochromic
rearview mirror assembly for a vehicle includes an electrochromic mirror having
a variable reflectivity, a glare sensor for sensing levels of light directed towards
the front element from the rear of the vehicle, an ambient sensor for sensing levels
of ambient light, a display positioned behind the partially transmissive, partially
reflective portion of the reflector for displaying information therethrough; and
a control circuit coupled to the sensors and the display. The control circuit determines
whether daytime or nighttime conditions are present as a function of the ambient
light level sensed by the ambient sensor. During daytime conditions, the control
circuit responds to light levels sensed by the glare sensor to control a contrast
ratio of light originating from the display and light reflecting from the partially
transmissive, partially reflective area of the reflector.