High frequency heating apparatus with a temperature compensated switching element

Claim 1

A high frequency heating apparatus comprising: a) rectification means for converting an AC voltage to a DC voltage; b) inverter means comprising a switching element and inductance coil means, the DC voltage from the rectification means being applied to the inductance coil means through the switching element which is turned on and off such that a high frequency voltage is obtained; c) a magnetron; d) a high frequency rectifying circuit for rectifying an AC voltage from the inverter means to a DC voltage and for applying it to the magnetron; e) control circuit means for controlling the "on" and "off" periods of the switching element so that the anode current of the magnetron is controlled; f) temperature sensing means for sensing the temperature of the switching element, thereby producing a temperature signal; and g) compensation means for compensating the "on" and "off" periods of the switching element in response to the temperature signal so that an increase in the magnetron anode current is restrained with an increase of the temperature of the switching element sensed by the temperature sensing means.