Abstract: A layer of conductive polymer having a positive temperature coefficient (PTC) of resistivity and a uniform thickness, is laminated between copper foils to form a composite sheet which is die-cut to form a planar heater assembly. A small portion of the laminated heater assembly is bent laterally outwardly to form a connector tab, and the heater assembly is adhesively bonded to the back surface of a rear view mirror having a corresponding shape and size. A plastic case supports the mirror and spring-like electrical contact terminals which engage the copper foils on the tab, and the terminals are connected to electrical conductors to provide for heating the entire mirror according to variations in temperature on the mirror surface. The tab may be lanced from the heater assembly or be formed from a projecting edge portion, and the heater assembly may be enclosed within a flexible plastic film to provide resistance to chemical corrosion.

Abstract: A layer of conductive polymer having a positive temperature coefficient (PTC) of resistivity and a unifrom thickness, is laminated between copper foils to form a composite sheet which is die-cut to form a planar heater assembly. A small portion of the laminated heater assembly is bent laterally outwardly to form a connector tab, and the heater assembly is adhesively bonded to the back surface of a rear view mirror having a corresponding shape and size. A plastic case supports the mirror and spring-like electrical contact terminals which engage the copper foils on the tab, and the terminals are connected to electrical conductors to provide for heating the entire mirror according to variations in temperature on the mirror surface. The tab may be lanced from the heater assembly or be formed from a projecting edge portion, and the heater assembly may be enclosed within a flexible plastic film to provide resistance to chemical corrosion.