Patent attributes
An infrared sensor includes an infrared detection element which is provided on a lower side of a top plate to detect an amount of infrared light radiated from a heated object and an amplifier to amplify a signal detected by the infrared detection element. The infrared sensor outputs an initial detection value having a substantially constant magnitude with respect to the temperature of the heated object when the temperature of the heated object is lower than a detection lower limit temperature, and outputs a detection signal having a magnitude and a rate of increase which become larger as the temperature of the heated object becomes higher in the vicinity of a control temperature range in which the control unit controls the output of the induction heating coils to perform temperature control of the heated object. The control unit includes a storage unit to measure and store the initial detection value, and reduces the output of the induction heating coils or stops the heating when an increased amount of the output value of the infrared sensor with respect to the initial detection value stored in the storage unit becomes greater than or equal to a predetermined value.
