US Patent 7268797 Image forming apparatus and method of controlling same

One scanning interval of a laser beam is divided into a plurality of blocks, correction data, which corresponds to optical characteristics of an optical unit placed between a laser element and a photosensitive drum, is stored in memory in association with each block, the correction data corresponding to a block being scanned by the laser beam is read out of the memory, and the laser is driven upon correcting the laser drive signal based upon the correction data read out and correction data corresponding to a block adjacent to the block being scanned by the laser.