Fixing device and image forming apparatus

Abstract

The present invention provides a fixing device and an image forming apparatus that suppress a fixing failure due to a change in nip width. The fixing device fixes a toner image to a sheet passing through a fixing nip, and is provided with: a first fixing part to which a first driving force is transmitted and which rotates; a second fixing portion that forms a fixing nip with the first fixing portion and that is driven to rotate by rotation of the first fixing portion; a nip width adjustment unit capable of adjusting the nip width of the fixing nip; a rotation speed detection unit that detectsthe rotation speed of the second fixing unit; and a control unit that controls the nip width adjustment unit such that the nip width reaches a predetermined reference nip width on the basis of the detection result of the rotational speed detection unit.

Description

technical field [0001] The present invention relates to a fixing device and an image forming device. Background technique [0002] In general, an image forming apparatus (printer, copier, facsimile, etc.) using electrophotographic technology forms an electrostatic latent image by irradiating (exposing) a charged photosensitive drum (image carrier) with laser light based on image data. Then, by supplying toner from a developing device to the photosensitive drum on which the electrostatic latent image has been formed, the electrostatic latent image is visualized to form a toner image. Then, after the toner image is directly or indirectly transferred to the paper, it is fixed by heating and pressurizing in the fixing nip to form the toner image on the paper. [0003] In an image forming apparatus, various kinds of media are used. Examples of various types of media include media with different basis weights, media with coating on the surface, media without coating, media with ...

AI Technical Summary

Problems solved by technology

[0008] However, in the technology described in Patent Document 1, it is only expected to offset the fluctuation of the nip width by the expansion of the inter-shaft restricting member, and it is still not possible to cope with the changes in the outer diameter and hardness of the roll due to the influence of heat and pressure. Correctly adjust the nip width

For example, when the nip width changes due to conditions other than media such as the expansion degree of the fixing member caused by the change of the heating state in the fixing device, aging of the fixing member, etc., a decrease in the fixing performance occurs, or a problem occurs during paper feeding. Problems such as fusing defects such as thin paper wrinkles

[0009] In addition, in the configuration described in Patent Document 1, the actual nip width is not measured, and therefore it may not be possible to adjust to the correct nip width. As a configuration for suppressing fixing failures caused by changes in the nip width, there is certain limit

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