| 摘要 |
A heating device (112) for a mirror includes a substrate (114) having an electrical buss system deposited on one surface thereof including a plurality of interdigitated electrodes (132,134) and two buss bars (116,118). A plurality of heater-lets (144) are formed of an electrically resistive layer of material having a positive temperature coefficient of resistance. The plurality of heater-lets (144) have different sizes and shapes (144a,b,c) and are deposited over the electrical buss system between adjacent interdigitated electrodes (132,134). Each of the heater-lets (144) is separated from its neighbour by spaces (146) with correspondingly different sizes and shapes so as to form a plurality of individual heating areas (A,B,C) of variable intensity. A first adhesive layer (147) is deposited over the resistive layer (144) and adheres to exposed areas of the substrate (114) in the spaces (146). An electrical barrier layer (150) is preferably secured by the first adhesive layer (147), and carries a second adhesive layer (152). A removable protective covering (154) is preferably secured to the second adhesive layer (152). The power distribution over the entire substrate hence over a mirror is selectively regulated by varying the density of the heater-lets (144). |
