Abstract Circuitry in a temperature regulator for the thermal fixing device of a duplicator comprising a source of electric power, a heater in the thermal fixing device supplied from the electric power source, a first controllable current regulating element responsive to a first control signal for regulating the current from the electric power source to the heater, a temperature detecting terminal directly connected to the heater for detecting the temperature thereof and providing a second control signal indicative of the temperature, a temperature regulator responsive to the second control signal for generating the first control to maintain the temperature of the heater at a substantially constant level, protective circuitry responsive to the substantial reduction of the second control signal for disconnecting the heater from the electric power source whereby if the temperature detecting terminal becomes disconnected from the heater, overheating of the heater is prevented.
Circuitry in a temperature regulator for the thermal fixing device of a duplicator comprising: a source of electric power; a heater in said thermal fixing device supplied from said electric power source; a first controllable current regulating element responsive to a first control signal for regulating the current from said electric power source to said heater; a temperature detecting terminal electrically connected to said heater for detecting the temperature thereof and providing a second control signal indicative of said temperature; a temperature regulator responsive to said second control signal for generating said first control to maintain the temperature of said heater at a substantially constant level; protective circuitry responsive to the physical disconnection of said temperature detecting terminal from said heater for disconnecting said heater from said electric power source whereby if said temperature detecting terminal becomes disconnected from said heater, overheating of said heater is prevented.
Claim 2
Dependent Claim
147 words
Circuitry in a temperature regulator for the thermal fixing device of a duplicator comprising: a source of electric power; a heater in said thermal fixing device supplied from said electric power source; a first controllable current regulating element responsive to a first control signal for regulating the current from said electric power source to said heater; a temperature detecting terminal electrically connected to said heater for detecting the temperature thereof and providing a second control signal indicative of said temperature; a temperature regulator responsive to said second control signal for generating said first control to maintain the temperature of said heater at a substantially constant level; protective circuitry responsive to the physical disconnection of said temperature detecting terminal from said heater for disconnecting said heater from said electric power source whereby if said temperature detecting terminal becomes disconnected from said heater, overheating of said heater is prevented.
Claim 3
Dependent Claim
57 words
Circuitry as in claim 1 where said protective circuitry includes a second controllable current regulating element responsive to said physical disconnection of said temperature detecting terminal from said heater; and a controllable switch responsive to said second controllable current regulating element sensing said physical disconnection for disconnecting said temperature regulator from said first controllable current regulating element.