Patent ID: 7746366

Claim:
An image output apparatus which is connected to a printing engine, wherein the printing engine includes a plurality of laser beam control units for controlling a plurality of laser outputs to a single photosensitive drum on the basis of input video signals, said image output apparatus comprising: a plurality of output units which output video signals based on print data to the respective laser beam control units for the single photosensitive drum in synchronization with a clock signal; and a plurality of clock control units which are arranged in correspondence with respective groups of plural ones of said output units, wherein each group is prepared by grouping plural ones of said plurality of output units so as to decrease a difference in optical paths to the single photosensitive drum between laser beams controlled by the corresponding laser beam control unit, wherein optical path lengths of the laser beams are inconsistent in a direction orthogonal to a main scan direction for the single photosensitive drum, wherein the difference in the optical paths is caused at least in part by the fact that the single photosensitive drum is cylindrical, and at least in part by the fact that the optical path lengths of the laser beams are inconsistent in the direction orthogonal to the main scan direction for the single photosensitive drum, and wherein each of said clock control units generates the clock signal on the basis of a synchronizing signal generated in an image forming operation of the printing engine, and outputs the generated clock signal to all output units belonging to a corresponding group.