Patent ID: 8338758

Claim:
A heater power control circuit comprising: a direct-current power source; a heater; a switching circuit that is connected to the direct-current power source and is configured to switch on/off a voltage supplied from the direct-current power source to control a power of the heater; a voltage smoothing circuit that is disposed between the heater and the switching circuit and is configured to convert the voltage into an analog voltage signal by smoothing a voltage signal obtained by switching on/off the voltage; a heater control circuit connected to the switching circuit to control switching of the switching circuit according to a voltage indicator signal; and a voltage comparator circuit connected between the heater control circuit and the heater to compare a value of the voltage indicator signal with a value of the analog voltage signal; wherein the heater control circuit is configured to control the power of the heater by controlling the switching on/off of the switching circuit based on a comparison result by the voltage comparator circuit, convert the voltage indicator signal into a time-dispersed voltage indicator signal which is obtained in a time-dispersed manner so that a variation of the voltage indicator signal per predetermined time becomes within a predetermined amount, and supply the time-dispersed voltage indicator signal to the switching circuit.