Electrochromic mirror for vehicles

An exterior rearview mirror having a manually activated heating system suitable for use on a vehicle comprising:

• an electrochromic reflective element having an electrochromically active area, said electrochromic reflective element including a first glass plate having a front and rear surface, said rear surface of said first glass plate coated with a transparent conductor, a second glass plate having a front and rear surface, and an electrochromic medium and a metal reflective layer disposed between the rear surface of said first glass plate and the front surface of said second glass plate, said electrochromic medium being between said transparent conductor and said metal reflective layer;
• said front surface of said first glass plate being subject to frosting when exposed to an outdoor environment at a temperature of 0.degree. C. or lower;
• electrical means to achieve an electrochromic function for supplying a signal to said reflective element between said transparent conductor and said metal reflective layer in order to establish the reflectance level of said reflective element;
• heating means to achieve a defrosting function on said rear surface of said second glass plate wherein said heating means is hidden from view by said metal reflective layer, said heating means heating said second glass plate in order to enhance coloration and bleaching of said electrochromic reflective element during low temperature operation and to defrost said front surface of said first glass plate, wherein said heating means includes one of a positive temperature coefficient material, a metal layer, and a transparent conductor layer;
• said heating means being electrically insulated by said second glass plate from said electrochromic medium and said metal reflective layer;
• and
• manually activated control means for applying energy in the form of direct current from an automobile power system to said heating means wherein said control means includes a defrost initiate means that is manually actuated when frost is present on said front surface of said first glass plate.