| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixing device which has high heat generation efficiency and heating-up characteristic and obviates the occurrence of a fixing defect even when the device is used for image forming devices of a middle speed and high speed. SOLUTION: The coil assembly 13 of the induction heating and fixing device generates induction currents in the nip part 16 of a fixing sleeve 12 and generates the magnetic fluxes which generate the induction currents in regions exclusive of the nip part 16 as well. Further, the conditions S1+S2>=0.3×S3, 0.2<=S2/(S1+S2)<=0.8, 1mm<=Dmax<=5mm are satisfied. In the equations, S1 is the sectional area of the core 18 at the axial orthogonal crossing plane of a holder 14; S2 is the sectional area of the coil 20; S3 is the sectional area of the bore of the fixing sleeve 12; Dmax is the max. distance of the spacing formed between the outer peripheral surface of the holder 14 and the inner peripheral surface of the fixing sleeve 12.
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