Patent ID: 7200350
Filing Date: 2007-04-03
Classification: G03G

Abstract:
1. A color electrophotographic image forming apparatus for forming an image on a recording material, said apparatus comprising: (i) a mounting portion configured and positioned to detachably mount a plurality of process cartridges substantially along a vertical line, said process cartridges each including an electrophotographic photosensitive drum and a developing roller configured and positioned to develop an electrostatic latent image formed on the electrophotographic photosensitive drum, wherein the developing roller is movable between a contact state where the developing roller contacts the electrophotographic photosensitive drum and a spaced state where the developing roller is spaced from the electrophotographic photosensitive drum, wherein the process cartridges develop the electrostatic latent images with colors different from each other including black developer and non-black developers; (ii) a driving force transmitting member configured and positioned to selectively transmit a driving force for rotating the electrophotographic photosensitive drum to the process cartridges; (iii) switching means for switching the developing rollers between the contact state and the spaced state when the process cartridges are set in said mounting portion; (iv) a feeding belt configured and positioned to feed the recording material along all of the electrophotographic photosensitive drums of the process cartridges set in the mounting portion; (v) a first transfer roller which is rotatable is supported on a main assembly of said color electrophotographic image forming apparatus and which is urged toward said electrophotographic photosensitive drum provided in the process cartridge containing a black developer, with said feeding belt interposed therebetween; (vi) a transfer roller unit which is rotatable is supported on the main assembly of said color electrophotographic image forming apparatus and which rotatably supports a plurality of second transfer rollers, wherein said transfer roller unit is movable between a contact position wherein said second transfer rollers are urged toward said electrophotographic photosensitive drums provided in the process cartridges containing non-black developers, with said feeding belt interposed therebetween, and a spacing position wherein said second transfer rollers are not urged toward said electrophotographic photosensitive drums provided in the process cartridges containing non-black developers; and (vii) control means for determining the kind of recording material and for switching, in accordance with the determined kind of the recording material on which an image is formed in a monochromatic image forming operation, between a first mode in which said transfer roller unit is placed at said contact position, and a second mode in which said transfer roller unit is placed at said spacing position; wherein in the monochromatic image forming operation, the image is formed on the recording material through development performed in only one of said process cartridges, and wherein in a process cartridge in which no development is performed in the monochromatic image forming operation, said switching means switches the developing roller to be in the spaced state.