Patent ID: 7488920

Claim:
A cooking appliance comprising: a cooking plate; a warning indicator for indicating when the cooking plate is hot; an insulating base located below and spaced a distance from the cooking plate; a peripheral insulating ring positioned between the insulating base and the cooking plate, the cooking plate, insulating base and insulating ring defining an internal air cavity; a heating element positioned on or within at least a portion of the insulating base for heating the cooking plate; and a thermal sensor comprising a housing formed by a heat insulated body and a thermally conductive base, the housing located entirely within the internal air cavity and spaced a distance from the peripheral insulating ring, the thermally conductive base situated in close proximity to the heating element, the thermal sensor further comprising a bimetallic element thermally coupled to the conductive base and mechanically coupled to an electrical switch, the electrical switch electrically coupled to the warning indicator, the bimetallic element configured to act upon the electrical switch to activate the warning indicator when the temperature of the conductive base is at a designated temperature or within a designated temperature range.