Image forming apparatus and toner collection method

Abstract

There is provided a technique in which in a four-rotation intermediate transfer system image forming apparatus, even in a state where a large amount of transfer residual toner is generated, the occurrence of color mixture of toners can be effectively suppressed. The image forming apparatus of a cleanerless process includes a development unit to movably hold plural developing devices to form images with toners of colors different from each other and to move a desired developing device to a specified development position opposite to the image bearing body by the movement, a collection unit capable of changing a mode between a collection mode of collecting the toner remaining on the image bearing body at a specified collection position of the image bearing body and a non-collection mode of not performing toner collection from the image bearing body, and a control unit to set, when a first developing device is changed to a second developing device in the development unit, the collection unit into the collection mode only in a specified period within a period from a second timing earlier than a first timing when the first developing device is changed to the second developing device by a time required for an image bearing surface of the image bearing body to move from the specified collection position to the specified development position to a third timing when a rear end of an area where the toner image is formed by the first developing device before the second developing device on the image bearing body reaches the specified collection position.

Dependencies are inferred from the claim text.