| 摘要 |
PROBLEM TO BE SOLVED: To suppress the over (under) shoot of feedback control. SOLUTION: A feedback controller for controlling a heater 21 of a heat treatment furnace 20 is provided with a temperature sensor 22, a subtracting part 23, a controlling part 24, a heater driving device 25, and a target value setting part 26, and the controlling part 24 is provided with a PD arithmetic part 31, an integration arithmetic part 32, an adding part 33, a first output limiting part 34, a second output limiting part 35, and an integration suppressing part 36. When a control signal from the adding part 33 is 0-3% of an allowable output range, that is, 'capability to decrease the temperature of the heater is small', the surplus integration of the integration arithmetic part 32 is prevented by the integration suppressing part 36. Therefore, the surplus integration can be prevented so that the controlled variable (temperature) can be quickly and exactly changed to a target value, and that the oversheet or undershoot of the temperature of the heat treatment furnace can be reduced. Thus, the quality of the heat treatment, the reliability, and manufacture yield of the devices can be improved.
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