Patent ID: 8219260

Claim:
A temperature control apparatus comprising: a resistance heater whose resistance value changes depending on a temperature of the resistance heater; a signal generator to output a control signal having two voltage levels including a first-voltage and a second-voltage which is different from the first-voltage; an adder to constantly add a superimposing voltage to the control signal, the superimposing voltage being set to a constant voltage level; a switching section which receives from the adder a signal obtained by adding the superimposing voltage to the control signal, to flow a first current that corresponds to a voltage obtained by adding the superimposing voltage to the first-voltage through the resistance heater when the voltage level of the control signal is the first-voltage, and to flow a second current, that corresponds to a voltage obtained by adding the superimposing voltage to the second-voltage and that has a current value smaller than a current value of the first current, through the resistance heater when the voltage level of the control signal is the second-voltage; and a voltage measuring instrument to measure a voltage value across the resistance heater at a time when the second current flows through the resistance heater, wherein the signal generator controls the temperature of the resistance heater by controlling the control signal based on the voltage value measured by the voltage measuring instrument.