Photographic fixing roller, fixing device and image forming device

Abstract

The invention provides a photographic fixing roller, a fixing device and an image forming device, which can keep the uniformity of a clamping part while preventing a wheel belt from deteriorating and deviating. A flexible layer (12) of the photographic fixing roller (1) is provided with multiple projections (13) continuously extending from the axial center O of the flexible layer to end parts L and R and symmetrical to the center O. Each projection (13) comprises a right conical surface S with a higher end adjacent to the center O and a lower end adjacent to the ends L and R. Namely, in the photographic fixing roller, the multiple right conical surfaces S are continuously arranged from the center O to the ends L and R with the center O as the symmetrical point. The projections (13) are defined in a way that the sum of the right conical step difference Ht in each right conical surface S is a necessary predetermined deviation preventing value for preventing heating wheel belts from deviating.

Description

technical field [0001] The present invention relates to a fixing roller for fixing an unfixed toner image in an electrophotographic copier, printer, and facsimile, a fixing device having the fixing roller, and an image forming apparatus having the fixing device. Background technique [0002] In photocopiers, printers, facsimiles, and other image forming devices using electrophotography, a fixing device is installed to heat the toner image that has been developed and has not been fixed on a sheet-like recording medium such as transfer paper or OHP. . One of the fixing methods employed in this fixing device is the heated belt fixing method. In this heating belt fixing method, an endless heating belt that is heated by heating means such as a radiator is rotatably stretched over the fixing roller and is arranged in parallel at a distance from the fixing roller. The support roller, and the heating belt is sandwiched between them so that the pressure roller is pressed into the f...

AI Technical Summary

Problems solved by technology

However, in the conventional positive crown-shaped fixing roller having such a pair of positive conical surfaces S, it is necessary to set the positive conical step difference Ht to the above-mentioned deviation preventing value Hs for It is a relatively large value to reliably prevent the deflection phenomenon of the heating belt. When the deflection prevention value Hs is ensured by a pair of right conical surfaces S provided in the fixing roller, the fixing roller 901 The difference between the outer diameter a of the center O and the outer diameters b, c of the two ends expands, resulting in a problem of unevenness in the width or pressure of the nip formed between the fixing roller 901 and the pressure roller to be pressed.

[0015] In addition, to solve this problem, as shown in Patent Document 3, the shape of the fixing roller is adapted to the shape of the fixing roller by forming the fixing roller into a reverse crown shape in which the outer diameter near the center is small and gradually increases toward both ends. The difference between the outer diameter of the center and the outer diameters of both ends is enlarged, and the width and pressure of the nip portion can be made uniform, but because this technology cannot solve the above-mentioned difference itself, the above-mentioned difference is caused by the fixing roller. The difference between the length of the outer circumference near the center and the length of the outer circumference near both ends will cause the stress in the heating belt to bend in the width direction and cause the deformation of the heating belt, thereby accelerating the deterioration of the heating belt. question

That is to say, the deterioration and deflection of the heating tire and the uniformity of the clamping part cannot be solved at the same time

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