Patent ID: 8044986
Filing Date: 2011-10-25
Classification: G03G

Abstract:
1. A color image forming apparatus comprising: a plurality of laser beam generating units corresponding to a plurality of colors, each of the laser beam generating units being configured to emit a laser beam based on image data output from an image data generating unit; a plurality of photosensitive members configured to be exposed by optical scanning performed by the plurality of laser beam generating units and to have respective electrostatic latent images formed thereon; a plurality of developing units configured to develop the respective electrostatic latent images formed on the plurality of photosensitive members; and a detecting unit configured to read an image of a color misregistration detection pattern for each color formed by irradiation with a laser beam from the plurality of laser beam generating units and detect an amount of color misregistration, the amount of color misregistration being a relative positional displacement between the colors, wherein the color image forming apparatus is operable in a plurality of operation modes including a first operation mode in which an optical scanning speed is a first scanning speed and a second operation mode in which the optical scanning speed is a second scanning speed different from the first scanning speed, wherein the plurality of laser beam generating units perform scanning in a first scanning direction on a first color and scanning in a second scanning direction on a second color, the first scanning direction being different from the second scanning direction, wherein a delay time from output of a synchronization signal for synchronizing image writing timing in a main scanning direction in image formation to reception of the image data output from the image data generating unit in response to the output synchronization signal by the plurality of laser beam generating units occurs, wherein, in the first operation mode, at least one of the plurality of laser beam generating units emits a laser beam with image writing timing that enables influence of the delay time to be reduced and forms the image of the color misregistration detection pattern, wherein the detecting unit detects the amount of color misregistration, which is the relative positional displacement between the colors, based on reading of the image of the color misregistration detection pattern performed by irradiation with the laser beam with the image writing timing that enables the delay time to be reduced, and wherein, in the second operation mode, the image writing timing that enables the delay time to be reduced is revised based on the amount of color misregistration detected by the detecting unit, and at least one of the plurality of laser beam generating units emits a laser beam with the revised image writing timing.