Patent ID: 8614727

Claim:
An image forming apparatus comprising: a photosensitive member configured to be driven to rotate by a drive unit, wherein the photosensitive member includes a first mark and a plurality of second marks whose shape is different from a shape of the first mark, and the first mark and the plurality of second marks are disposed along the rotational direction of the photosensitive member; an exposure unit configured to expose the photosensitive member; a detection unit configured to detect the first mark and the plurality of second marks; an output unit configured to output correction data corresponding to the first mark and each of the plurality of second marks detected by the detection unit; a control unit configured to control an exposure intensity of the exposure unit based on the correction data output by the output unit, wherein the output unit is a storage unit configured to store correction data corresponding to the first mark and each of the plurality of second marks, and the storage unit outputs correction data corresponding to the first mark based on detection of the first mark by the detection unit and correction data corresponding to any one of the plurality of the second marks detected by the detection unit based on detection of any one of the plurality of the second marks detected by the detection unit; and a counting unit configured to reset a count value if the detection unit detects the first mark, and count the number of the detection signal which is output from the detection unit in accordance with detecting the second mark after the detection of the first mark, wherein the correction data corresponding to the plurality of second marks is correction data corresponding to the count value counted by the counting unit, and wherein the control unit controls the exposure intensity according to the correction data based on the count value of the counting unit.