Patent ID: 6248983
Filing Date: 2001-06-19
Classification: G05D,H05B

Abstract:
A heater control apparatus comprising a power element for exciting a heater, a temperature detection element for detecting a temperature of the heater or an object heated by the heater, an exciting current control circuit having a zero crossing detecting circuit for detecting the zero crossing point of an input voltage, and an input voltage discrimination circuit for discriminating levels of the input voltage, and a temperature control circuit for generating an exciting current control signal for the power element, wherein in case that the input voltage applied by an AC power supply is the lowest level, the heater is excited by a current corresponding to a full-wave of the input voltage, and in case that the input voltage applied by an AC power supply is a level other than the lowest level, the heater is excited by a current substantially equal to that in the case of the input voltage of the lowest level, the current in case of the level other than the lowest level being obtained by setting a range of an applying time of the input voltage to the heater according to the input voltage level of the AC power source and the frequency thereof.