Fixing device and image forming apparatus

Abstract

The invention provides a fixing device and an image forming apparatu. The fixing device includes a pressing roller, a rotating member, a heating means, a pressing mechanism, a separation member, a first biasing member and a moving mechanism. The pressing roller has a core metal and an elastic layer. The rotating member is configured to come into contact with an outer circumferential face of the pressing roller. The heating means is configured to heat the rotating member. The pressing mechanism is configured to press the pressing roller to the rotating member to form a pressing area between thepressing roller and the rotating member. The separation member is arranged at a downstream side of the pressing area in a conveyance direction of the sheet and configured to separate the sheet from the rotating member. The separation member includes a rotating shaft part and a contact part. The first biasing member is configured to bias the separation member to be rotated in a direction in whichthe contact part is butted against the outer circumferential face of the rotating member. The first biasing member includes a first end portion and a second end portion. The moving mechanism is configured to move the second end portion of the first biasing member in a direction in which the biasing force is decreased, as the core metal approaches the rotating member owing to decrease in rigidity of the elastic layer of the pressing roller. According to the present invention, it is possible to suppress wear of the rotating member when the hardness of the elastic layer of the pressing roller decreases.

Description

technical field [0001] The present invention relates to a fixing device for fixing a toner image on paper, and an image forming apparatus having the fixing device. Background technique [0002] As a structure of a fixing device for fixing toner to paper, a structure having a pressure roller, a rotating member (fixing roller, fixing belt, etc.), a heating mechanism, and a pressure mechanism is known, wherein the pressure The roller has a mandrel and an elastic layer; the rotating member is in contact with the outer peripheral surface of the pressure roller; the heating mechanism heats the rotating member; Forms a pressurized area where paper is conveyed while being clamped. A release layer made of fluororesin or the like is formed on the outer peripheral surface of the rotating member in order to promote release of the toner. [0003] In the above-mentioned fixing device, there is known a technique for separating the paper attached to the rotating member from the rotating m...

AI Technical Summary

Problems solved by technology

Then, the cohesive force of the toner is lowered, and therefore, the paper is easily separated from the rotating member

[0006] However, in the above-mentioned structure, even if the hardness of the elastic layer of the pressure roller is lowered, the load that makes the separating member touch the rotating member does not change, and therefore, the wear of the rotating member is increased due to the additional load.

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