Patent ID: 7715768

Claim:
A color image forming device comprising: a plurality of first image support mediums of respective color components each adapted to support a color component image on a photoconductor surface respectively; a scanning exposure unit adapted to output a scanning light beam, generated in accordance with a line image signal of a main scanning direction, to each of the photoconductor surfaces of the color components of the first image support mediums at a predetermined cycle while the photoconductor surfaces are moved in a sub-scanning direction perpendicular to the main scanning direction, so that a two-dimensional color-component image is formed on each photoconductor surface by exposure to the scanning beam light; a second image support medium adapted to receive the color component images transferred from the first image support mediums of the respective color components to support a color composite image produced by the received color component images; a second image support medium transport unit transporting the second image support medium through image transfer positions of the respective color components in synchronization with movement of the first image support mediums of the respective color components in the sub-scanning direction; a transfer unit transferring the color component images from the first image support mediums of the color components to the second image support medium; a correction-pattern-image forming unit controlling the scanning exposure unit to form correction pattern images, each adapted for correcting the image formation operating states for the color component concerned, in predetermined areas arrayed on the seocond image support medium in the sub-scanning direction; a pattern measurement unit measuring the correction pattern images formed on the second image support medium by the correction-pattern-image forming unit; and a control unit correcting the image formation operating states for the respective color components in accordance with a result of the measurement of the pattern measurement unit to control image formation operation of the color image forming device, wherein “a” is the length of a correction pattern image in the sub-scanning direction, “b” is the distance between adjacent image transfer positions of the respective color components in the sub-scanning direction, and the correction pattern image forming unit is arranged so that, when a>b, at completion of formation of a correction pattern image on the first image support medium of the color component which is the first in a sequence of the color components in the sub-scanning direction, write-enable signals for forming correction-pattern images on the first image support mediums of the other color components are deactivated.