Integrated assembly of thermostat and thermistor in fixing device of image reproduction machine

Claim 1

A heat fixing device for an image reproduction machine comprising: a heat source for providing heat to said heat fixing device; a power source for providing power to said heat source; a temperature sensing thermistor for sensing the temperature of said heat fixing device; silicon rubber formed around at least a portion of said thermistor for protecting said thermistor from the surrounding environment; a temperature control circuit, responsive to said temperature sensing thermistor, for generating signals representative of changes in resistance of said thermistor, said signals corresponding to varying temperatures being sensed; means for applying power to said heat source in response to said signals generated by said temperature control circuit when the temperature of said heat fixing device is below a predetermined temperature, said signals being applied to said power source of said heat source; a thermostat, integrally combined with said temperature sensing thermistor, for detecting an abnormal increase in the temperature of said heat fixing device upon failure or malfunction of at least one of said power source, said temperature sensing thermistor, and said temperature control circuit, whereby said thermostat interrupts said means for applying power to said heat source, thereby preventing damage to said heat fixing device; and wherein heat is transferred to said thermostat through said silicon rubber around said thermistor.