Patent ID: 7658462

Claim:
An apparatus for controlling color registration and an image density, comprising: registration marks for different colors arranged on an image carrying member of a printer in a cross-scan direction, the image carrying member movable in the cross-scan direction; image density marks for different colors arranged on the image carrying member in a cross-scan direction, each of the image density marks for different colors having a plurality of gray level marks; an optical module disposed at a fixed position with respect to the image carrying member so as to detect the registration marks arranged thereon as the image carrying member moves in the cross-scan direction, wherein the optical module further detects the image density marks arranged thereon as the image carrying member moves in the cross-scan direction while the optical module remains in the same fixed position with respect to the image carrying member, optical module comprising a light emitter to radiate a spot shaped beam onto the registration marks and the image density marks and a light receiver to receive the beam reflected from the registration marks and the image density marks; and a controller to control the printer to compensate for a color registration error and an image density error based on detection signals of the optical module corresponding to the registration marks for different colors and the plurality of gray level marks of each of the image density marks for different colors, respectively, wherein the registration marks comprise a first set of registration marks and a second set of registration marks, wherein the first set of registration marks and the second set of registration marks are separated from each other in a scan direction, wherein the image density marks comprise a first set of image density marks and a second set of image density marks, wherein the first set of image density marks and the second set of image density marks are separated from each other in the scan direction, wherein the first set of image density marks includes: image density marks corresponding to a first color, image density marks corresponding to a second color, image density marks corresponding to a third color, and image density marks corresponding to a fourth color, wherein the second set of image density marks includes: image density marks corresponding to the first color, image density marks corresponding to the second color, image density marks corresponding to the third color, and image density marks corresponding to the fourth color, the optical module includes a first optical module to detect the first set of registration marks and the first set of image density marks, and a second optical module that is separated from the first optical module in the scan direction and detects the second set of registration marks and the second set of image density marks.