Image forming apparatus, image forming method

Abstract

The invention provides an image forming apparatus and an image forming method. The image forming apparatus includes a plurality of image carriers, an intermediate transfer belt, a plurality of transfer rollers, a print control portion, and a contact pressure control portion. The plurality of transfer rollers are provided in such a way as to be in contact with the intermediate transfer belt at positions respectively corresponding to the image carriers. The print control portion executes a print process in a first print mode or a second print mode that are set in advance. The contact pressure control portion, when the print process is executed in the first print mode, reduces a contact pressure of one or more transfer rollers that are, among the plurality of transfer rollers, disposed on a downstream side in a conveyance direction of the intermediate transfer belt, to be lower than a contact pressure in the second print mode.

Description

technical field [0001] The present invention relates to an image forming apparatus and an image forming method capable of forming a color image. Background technique [0002] Generally, image forming apparatuses such as printers capable of electrophotographically forming color images are known to the public. In such an image forming apparatus, for example, toner images of various colors formed on image carriers such as a plurality of photosensitive drums are sequentially transferred to an intermediate transfer belt, and each image superimposed on the intermediate transfer belt is A toner image of one color is transferred to a transferred member such as a sheet to form a color image. [0003] However, in such an image forming apparatus, when printing a character image, a phenomenon called drop-out may occur. The phenomenon of drop-out means that a part of the toner image formed on the image carrier is not transferred to the intermediate transfer. belt, holes are formed in t...

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Problems solved by technology

[0004] However, when the contact pressure of all the transfer rollers is lowered as described above, the running of the intermediate transfer belt may become unstable, resulting in misregistration of the toner image formed on the intermediate transfer belt.

In addition, when other toner images are superimposed on the toner images that have been transferred to the intermediate transfer belt, intermediate drop-out is likely to occur.

Therefore, when only the contact pressure of the transfer roller for transferring the black toner image is lowered as in the above-mentioned related art, it is not possible to prevent the toner images of other colors, which have many overlapping times, from falling off during transfer.

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