| 摘要 |
A window defogging system that comprises a power supply and an optically clear overlay includes a sheet of heat-stabilized polyester (13) having a hard coat layer (15) on one surface and an indium tin oxide (ITO) layer (17) on the other surface. The ITO layer (17) is scored around its periphery (19) to create a groove that electrically isolates the edge of the ITO layer from an interior heating zone (23). Additional grooves create electrically isolated regions (26a, 26b, 28a and 28b). Multiple layers of silver are printed atop the ITO layer (17), along opposing edges of the interior (heater) zone (23), to create bus bars (25a, 25b). The bus bars end at terminal regions (29a, 29b) that are connected directly to the power supply. The housing (61) of the power supply is supported by connectors mounted in the optically clear overlay. In some versions of the invention, a dielectric layer (33a, 33b) is located along a portion of the bus bars, between the multiple layers of silver. The power supply includes a temperature-sensing device, e.g., a thermistor, that senses the temperature of the interior zone and uses this information to control the application of power to the ITO layer via the bus bars.
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