Fixing device and image forming device having same

Abstract

A fixing device (5) includes a heating member (26), a pressurizing member (19), a coil (37) wound in a loop shape in the width direction of the heating member (26) to generate a magnetic flux that inductively heats the heating member (26), and a magnetic core, disposed near the coil (37), that is configured to lead the magnetic flux to an inductive heat-generating layer (26a) formed in the heating member (26). The magnetic core includes first core parts (41) and second core parts (42). The first core parts (41) are placed so as to enclose the coil (37) in a direction orthogonal to a direction in which paper is conveyed. The second core parts (42) are placed in hollow parts formed by the loops of the coil (37) at both ends in the direction orthogonal to the paper conveyance direction. The second core parts (42) have a higher Curie temperature and a smaller thermal capacity than the first core parts (41).

Description

technical field [0001] The present invention relates to a fixing device and an image forming device including the fixing device. Background technique [0002] In a fixing device of an electromagnetic induction heating method, for example, an eddy current is generated in an induction heating layer provided in a heating member by a magnetic flux generated by an exciting coil. The heating member is heated by Joule heat generated by the eddy current, so that the heating member is heated to a predetermined fixing temperature. In such a fixing device, since the heat capacity of the heating member can be reduced, the warm-up time can be shortened, and high heat conversion efficiency can be obtained with a compact configuration. [0003] In such a fixing device, since the paper absorbs heat from the surface of the heating member, the temperature of the paper-passing area where the paper passes tends to decrease compared to the non-paper-passing area where the paper does not pass. ...

AI Technical Summary

Problems solved by technology

[0006] However, in the above-mentioned fixing device, it is considered that the temperature followability of the end magnetic core to the temperature change of the heating member is not satisfactory.

[0007] When the temperature followability of the end magnetic body core to the temperature change of the heating member is not ideal, after passing through the small-sized paper continuously, the temperature of the end magnetic body core corresponding to the non-passing paper area exceeds the Curie temperature. In the case of small-sized paper and large standard-sized paper, the heating of the non-passing paper area is insufficient, and the entire surface of the standard-sized paper cannot be heated and fixed uniformly, and fusing failure may occur

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