Patent ID: 8989642
Filing Date: 2015-03-24
Classification: G03G

Abstract:
1. A fixing device to fix an image on a recording medium, comprising: a heating member having an induction heating layer; a pressing member configured to contact the heating member and to form a nip portion with the heating member through which the recording medium with the image is to pass; and an induction heating unit comprising an induction heating coil and arranged along an outer circumferential surface of the heating member, the induction heating unit applying an electric current to the induction heating coil to generate a magnetic flux to heat the induction heating layer of the heating member; wherein the induction heating unit comprises a coil bobbin provided with a winding center portion on which a Litz wire is wound a plural number of laps; wherein the wound width of the induction heating coil is changed by winding the Litz wire along a step portion formed on the winding center portion; and wherein (i) a wound width We of a center portion of the induction heating coil in a longitudinal direction seen from an axial direction of the heating member, (ii) a wound width Wp in a vicinity of and inside edges of a maximum recording medium passing region of the recording medium, and (iii) a wound width We of at least one of both edges of the induction heating coil in the longitudinal direction satisfy parameters that the wound width Wc is smaller than the wound width Wp and is larger than or equal to the wound width We; wherein the wound width We of at least one of both edges in the longitudinal direction is smaller than the wound width Wc of the center portion in the longitudinal direction.