Transfer belt unit and image forming apparatus using the same

Abstract

An image forming apparatus includes a transfer belt unit which has an intermediate transfer belt for supporting toner images and primary transfer rollers for pressing the intermediate transfer belt against corresponding photoreceptor drums and moves the intermediate transfer belt along the surface of each photoreceptor drum to transfer the toner images to the intermediate transfer belt. The intermediate transfer belt is formed so as to be 30 mum to 50 mum in average thickness, each primary transfer roller is arranged at a position, along the moving direction of the intermediate transfer belt, which is deviated downstream with respect to the moving direction from the position where the intermediate transfer belt is in contact with the photoreceptor and which is projected toward the photoreceptor drum side so as to press the intermediate transfer belt against photoreceptor with a nip pressure ranging from 10 gf / cm2 to 40 gf / cm2.

Description

technical field [0001] The present invention relates to a transfer belt device for transferring a toner image formed on a surface of a photoreceptor by an electrophotographic image forming method using a belt-shaped intermediate transfer body, and an image forming apparatus using the transfer belt device . Background technique [0002] Conventionally, in an image forming apparatus that performs electrophotographic image formation, it is known that a toner image (hereinafter, referred to as a toner image) carried on the surface of a photoreceptor (photosensitive drum) is primarily transferred to an intermediate stage. The so-called intermediate transfer method in which after the transfer body (intermediate transfer belt) is transferred, the intermediate transfer is transferred from the intermediate transfer belt to a recording medium such as recording paper. [0003] In such an image forming apparatus of the intermediate transfer method, in order to realize high image qualit...

AI Technical Summary

Problems solved by technology

[0009] However, in recent image forming apparatuses, the fixing temperature has been lowered as a measure to save energy, and one of the responses is to lower the melting point of the toner. Problems prone to agglutination

[0010] That is, in the case of using a highly cohesive toner, since conventional intermediate transfer belts are mainly used with a thickness of 70 μm or more, excessively high pressing force tends to cause toner aggregation during primary transfer. , which results in deterioration of the secondary transfer property

[0011] In order to prevent this phenomenon, there is known an offset method in which a primary transfer roller is arranged on the downstream side of the photoreceptor so that the photoreceptor and the primary transfer roller do not directly contact each other. In this case, there is a new problem that the secondary transfer performance is low and the final image quality is deteriorated.

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