| 摘要 |
An image forming apparatus having a normal paper mode and a thick paper mode includes a scanning unit 6 which scans an image of an original, a process unit 55 which forms the image scanned by the scanning unit 6 onto a sheet P for image formation, and a fixing device 26 which fixes the image formed on the sheet P to the sheet by heating. The fixing device 26 includes a fixing roller 30, a center coil 33a for induction heating a substantially central part in the axial direction of the fixing roller 30, side coils 33b, 33c for induction-heating end parts in the axial direction of the fixing roller, induction heating power sources 60, 61, 70, 71 which supply a high-frequency pulse voltage to these coils, and a power control circuit 58a which variably controls output power of the induction heating power sources 60, 61, 70, 71 so that the output power increases or decreases stepwise on a predetermined cycle, and has a function of selectively setting maximum power supply and a function of selectively setting the output power variance cycle. If the thick paper mode is selected, the maximum power supply of the induction heating power sources 60, 61, 70, 71 is set to a smaller value than the maximum power supply in the normal paper mode, and the output power variance cycle is set to a larger value than the output power variance cycle in the normal paper mode.
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