| 摘要 |
A method is described of processing an electrical signal output from a sensor coil located in an electric heater for use under a cook top in a cooking appliance. The sensor coil is employed to operate a switch to switch on and off a heating element in the heater in accordance with placement and removal of a cooking utensil on and from the cook top. The sensor coil is arranged in the heater within magnetic influence of the electrical heating element, the heating element comprising a material which is ferromagnetic below and substantially non-ferromagnetic above a predetermined temperature within an operating temperature range of the heater. The occurrence of an increase in output signal level from the sensor coil is detected and closure of the switch is effected. Subsequently, the occurrence of a decrease in output signal level from the sensor coil is detected and opening of the switch is effected. The switch is opened for a predetermined period and closure of the switch means is subsequently effected unless within the predetermined time period a further decrease in output signal level, consecutive with the previous decrease in output signal level, is detected.
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