Patent ID: 8526867

Claim:
An image forming apparatus comprising: an image forming unit to form a color registration error detection pattern on a photoconductor; a transfer unit to transfer the color registration error detection pattern formed on the photoconductor to a transfer belt; a pattern sensing unit to sense the color registration error detection pattern transferred to the transfer belt; a motor drive unit to drive a motor used to rotate the photoconductor; a control unit to ascertain a gap change of the color registration error detection pattern, which denotes a periodic velocity change of the photoconductor, by sensing the color registration error detection pattern transferred to the transfer belt, and to change a velocity of the motor according to the gap change to reduce the periodic velocity change of the photoconductor; a home-position sensing unit to sense a home-position of the photoconductor, wherein the control unit forms the color registration error detection pattern on the photoconductor on the basis of a time when the home-position of the photoconductor is sensed.