Automatic rearview mirror incorporating light pipe

DETAILED DESCRIPTION This invention relates to light sensing means and, more particularly, to improved light sensing means adapted for use in automatic rearview mirrors for automotive vehicles.
As is well known in the art, automatic rearview mirrors for automotive vehicles have heretofore been designed to include multiple functions such as motorized positioning of mirror reflective elements, the control of the reflectivity of electrochromic elements, map lights, electronic compasses, and various other functions.
Such automatic rearview mirrors incorporate light sensors, such as cadmium sulfide photo-resistive light sensors or photo-diodes or other types of sensors, which are effective to control various functions of the mirror including the reflectivity of the mirror in response to light, such as ambient light, sensed forwardly of the vehicle, and light, such as glare causing light, sensed rearwardly of the vehicle.
At the same time, the printed circuit boards, to which the electrical components which perform the various mirror control functions are attached, are being made smaller.
Some of the cases or housings for the mirrors which perform multiple functions are too large and too thick for it to be practical to mount the required light sensor or sensors on the mirror printed circuit board.
Other situations may occur where the printed circuit board is too small to extend to the location or locations where each light level is viewed through an aperture in the mirror elements or in the mirror assembly housing.
In such situations one or more of the sensing functions are required to be performed by mounting the sensors separately from the printed circuit board or by using special means to direct the light from the sensing aperture to the respective sensor.
The latter approach is the one taken by the embodiments of automatic rearview mirrors described herein.
Heretofore automatic mirrors have normally used two light sensors, one to detect glare from the rear of a vehicle and one to detect the ambient light level, usually forwardly of the vehicle