Patent ID: 7289135

Claim:
A color image-forming apparatus, comprising: first and second latent-image forming media; first and second writing units configured to form latent images on the first and second latent-image forming media, respectively, by exposure; first and second developing devices developing latent images on the first and second latent-image forming media into toner images with first and second colors, respectively; third and fourth developing devices developing latent images on the first and second latent-image forming media into toner images with third and fourth colors, respectively; an intermediate transfer device successively passing the first and second latent-image forming media so that toner images developed on the first and second latent-image forming media are successively transferred onto the intermediate transfer device; a transfer unit transferring a multi-color toner image on the intermediate transfer device onto a recording medium; a control unit controlling the first and second writing units to form patterns of first, second, third, and fourth colors and controlling timing at which the first and second writing units write on the first and second latent-image forming media, respectively, such that the patterns approach one another; a correcting unit correcting timing at which the first and second writing units write latent images in response to image data on the basis of positional shifts in the patterns on the intermediate transfer device; and a detecting unit detecting the patterns on the intermediate transfer device, wherein each pattern includes two first lines of the same color and a second line of another color disposed between the two first lines, and wherein the correcting unit corrects the timing on the basis of the detection of the detecting unit.