Patent ID: 6163013
Filing Date: 2000-12-19
Classification: H05B

Abstract:
An automotive vehicle having a passenger compartment with window glass that separates the inside of the passenger compartment from the outside environment, an electric heating element disposed on said window glass for heating the same by means of electric power, an electric power source for providing electric power, and a control circuit for controlling the delivery of electric power from said electric power source to said electric heating element, characterized in that said control circuit comprises selectively operable conducting means connected between said electric power source and said electric heating element, and means for operating said selectively operable conducting means comprising an on-off switch means that is accessible to an operator of the vehicle, a temperature sensing switch means that is disposed in non-thermal sensing relationship to said electric heating element to reliably sense temperature indicative of the ambient temperature of the outside environment, and means operatively relating said on-off switch means and said temperature sensing switch means with said selectively operable conducting means for allowing electric power to be delivered from said electric power source through said selectively operable conducting means to said electric heating element responsive to said on-off switch means being on and said temperature sensing switch means indicating that the ambient temperature of the outside environment is below a certain threshold and for disallowing electric power to be delivered from said electric power source through said selectively operable conducting means to said electric heating element either responsive to said on-off switch means being off or said temperature sensing switch means indicating that the ambient temperature of the outside environment is above said threshold, characterized further in that said selectively operable conducting means is a relay having a coil and normally open contacts that are operated by said coil, said means operatively relating said on-off switch means and said temperature sensing switch means with said selectively operable conducting means comprises means connecting said coil in series with said on-off switch means and said temperature sensing switch means, and said contacts are connected between said electric power source and said electric heating element.