| 摘要 |
PROBLEM TO BE SOLVED: To provide a heater drive circuit capable of improving a print speed as much as possible under the condition where a total amount of available electric energy is limited, in an image forming device provided with a fixing heater. SOLUTION: An A.C. voltage supplied from an A.C. line filter is subjected to full-wave rectification, thereafter subjected to voltage conversion by a switching converter and applied to a heater. An FET acts as an element for controlling the turning on/off of the switching converter. An alternating current supplied from the A.C. line filter is supplied to a DI terminal of a heater control circuit after its current value is detected by a current transformer and a rectification circuit. The heater control circuit controls the turning on/off of the switching converter so that an A.C. line current supplied to the FET from the DI terminal approaches a predetermined value. Thereby, the current flowing through the heater is stabilized at a predetermined value, so that power supplied to the heater 112 is kept at a predetermined value. COPYRIGHT: (C)2005,JPO&NCIPI
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