Heated rearview mirror assembly

Claim 1

A resistance heated rear view mirror assembly for a motor vehicle, comprising: an electrically conductive motor support adapted to be mounted exterior of the vehicle in grounding relationship therewith; a housing on said mirror support having a generally rearwardly opening cavity, a ball stud connected to said mirror support and disposed interior of said cavity; a generally rectangular mirror element having a low thermal and electrical conductivity; a backing plate universally frictionally supported on said ball stud said backing plate being directly adhesively attached to the forwardly facing surface of said mirror element for thereby electrically insulating the latter from said mirror support while permitting adjustable universal movement of said mirror element about said ball stud within the confines of said cavity; a nontransmissive, electrically conductive reflective coating on the rearwardly facing exterior surface of said mirror element for establishing a rearward viewing surface, said coating being exposed to moisture in varying forms during inclement weather, switch means disposed interior of the vehicle; an elongated first current distributing contact secured along one edge of said mirror element in electrical contact with said coating; first conductor means electrically connecting said first current distributing contact in series with said power source and said switch means; and an elongated second current distributing contact secured along the opposite edge of said mirror element in electrical contact with said coating; second conductor means electrically connecting said second current distributing contact in electrical grounding relationship with said mirror support thereby establishing a uniform current path between said contacts and throughout the major portion of the viewing surface, whereby closing said switch means passes a heating current through said reflective coating to rapidly raise the temperature of the latter above the prevailing dew point temperature thereby removing any moisture accumulating on the coating, the low-thermal conductivity of said mirror element serving to retain heat at the coating to improve the thermal efficiency of the mirror assembly.