Patent ID: 8094177

Claim:
An image-forming device comprising: an image-forming unit comprising: a rotatable mirror; a light-emitting unit configured to repeatedly emit a laser beam toward the rotatable mirror, each laser beam being emitted over a predetermined period and reflected by the rotatable mirror; a photosensitive drum configured to rotate at a predetermined rotating speed to be subject to a scanning with each reflected laser beam, the scanning forming an electrostatic latent image composed of a plurality of line electrostatic latent images extending in a main scanning direction over a first length, wherein neighboring line electrostatic latent images are spaced apart by a second length; a developing unit configured to develop the electrostatic latent image with a developer to form a developer image; and a transferring unit configured to transfer the developer image formed on the photosensitive drum to a recording medium at a transferring position to form an image, the transferring unit overlapping a plurality of developer images on the recording medium to form the image, the plurality of developer images being developed with a plurality of developers different from one another; a first conveying unit configured to convey the recording medium to the transferring position in a sub-scanning direction orthogonal to the main scanning direction; a first changing unit configured to change a rotating speed of the rotatable mirror to change the first length; a second changing unit configured to proportionally change a conveying speed of the first conveying unit in accordance with the change of the rotating speed of the rotatable mirror; and a third changing unit configured to proportionally change a rotating speed of the photosensitive drum in accordance with the change of the rotating speed of the rotatable mirror, wherein the image-forming unit is configured to form a plurality of test patterns when a changing rate of the rotating speed of the rotatable mirror exceeds a predetermined value; an adjusting unit configured to adjust, in accordance with the change of the rotating speed of the rotatable mirror, a timing when the light-emitting unit emits the laser beam to adjust a position of the image in the sub-scanning direction, and a position of the image in the main scanning direction, a detecting unit configured to detect offsets of the plurality of test patterns from a predetermined position in the sub-scanning direction; and a producing unit configured to produce correction data based on the offsets, wherein the image-forming unit is configured to form the image based on the correction data.