Image forming apparatus and image forming method
AssigneeSeiko Epson Corporation
InventorItaru Kozuma
Life of this patent
Estimating the term…
Abstract
In a color printing mode of an image forming apparatus, two toner images in respective colors are formed and superimposed on an intermediate transfer belt. A gap D11 between toner images of the same color is narrowed while a gap D12 between toner images of different colors is widened, thereby corresponding to the switching of developers. In a printing mode that forms a monochrome image using one developer, gaps D21, D22 between the respective toner images are the same. In a printing mode that forms a monochrome image while switching four developers, a toner image formed immediately before the switching is shifted forward, thereby widening a gap D34 from the next toner image.
Claims11
An image forming apparatus, comprising:
- a positioning unit which is structured so as to mount plural developers holding toner of the same color and which selectively moves and positions one of the mounted developers to a predetermined development position;
- an image carrier which carries toner images on its surface and which rotates in a predetermined direction;
- and
- a controller which executes an image forming operation of forming a toner image using the developer positioned at the development position and making the image carrier carry the toner image,
- wherein when a switching distance is defined as a distance that the surface of the image carrier moves during a switching time which is necessary to switch from the developer positioned to the development position to other developer by the positioning unit,
- the controller executes, as the image forming operation of forming three or more pages of toner images on the image carrier one after another while securing predetermined inter-image regions between the toner images, a switching-involving image forming operation of forming a predetermined number of pages of toner images using one developer, making the positioning unit switch the developer at the development position to the next developer, and thereafter forming toner images of subsequent pages using the next developer, and
- gaps between the toner images formed on the image carrier during the switching-involving image forming operation taken along the direction in which the image carrier moves are equal to or longer than the switching distance in a first inter-image region which is between the toner images which are formed immediately before and immediately after the switching of the developers but shorter than the switching distance in other inter-image regions.
An image forming method of forming, on an endless image carrier which rotates in a predetermined direction, three or more pages of toner images one after another while securing predetermined inter-image regions between the toner images, comprising:
- selectively positioning plural developers holding toner of the same color to a predetermined development position;
- forming primarily a predetermined number of pages of toner images using the developer positioned at the development position and making the endless image carrier, which rotates in the predetermined direction, carry the toner images;
- switching from the developer which is at the development position to other developer after the image forming;
- and
- forming secondarily remaining pages of toner image using the developer newly positioned at the development position and making the image carrier carry the toner images,
- wherein when a switching distance is defined as a distance that the surface of the image carrier moves during a switching time which is necessary to switch from the developer which is positioned at the development position to other developer, and
- a gap between the respective toner images which are formed at the primary image and at the secondary image forming is shorter than the switching distance, while a gap between a toner image which is formed at the end of the primary image forming and a toner image which is formed at the beginning of the secondary image forming is equal to or longer than the switching distance.
Dependencies are inferred from the claim text.