Induction heating unit, fixing apparatus, and image forming apparatus

摘要

A magnetising coil (207) and demagnetising coils (215) are disposed in a fixing apparatus (115) that uses electromagnetic induction to heat a conductive heat-producing rotating body (206) and thermally fixes a toner image onto a recording sheet in one of a plurality of sizes. The magnetising coil (207) is arranged along the outer surface of the rotating body (206) and heats the rotating body (206) through electromagnetic induction heating. The demagnetising coils (215) are arranged in partially-overlapping proximity to the magnetising coil (207) and suppress overheating in a non-sheet-passing region of the rotating body (206) by partially cancelling out the flux produced by the magnetising coil (207) when fixing is performed on a small sheet. The demagnetising coils (215) are coil patterns (701) printed on a flexible substrate, and the wire width thereof is wider than the inter-wire distance of neighbouring wire segments.