TWI726682B

An objective of the present invention is to vitalize the performance of a heater to a sufficient level as long as there is no damage to the heater. A calculation part (103) calculates a temperature rise change per unit time of a heater (101) as measured by a measurement part (102) to determine the speed of the temperature rise. A first detection part (104) detects that a measurement temperature measured by the measurement part (102) exceeds a preset first value. A second detection part (105) detects that the temperature rise speed calculated by the calculation part (103) exceeds a preset second value. A first gauging part (106) gauges the duration for which the first detection part (104) is detecting that the measured temperature exceeds the first value, and also, the second detection part (105) is detecting that the temperature rise speed exceeds the second value. A determination part (107) determines a case in which the duration gauged by the first gauging part (106) exceeds a preset first time, as an abnor