Patent ID: 7894107

Claim:
An optical scanning device comprising: a laser array which emits laser beams including a number of beams (1, 2, . . . , n) writing a swath of rasters having a laser scanning section which, when an interlaced scanning period i, is set to a natural number between beams which are adjacent in a sub-scanning direction, scans the laser beams emitted from the laser array with the interlaced scanning period i, the laser scanning section scans the laser beams such that the beam number n and the interlaced scanning period i are relatively prime natural numbers, and n>i; wherein in a first scan, data for raster lines (1, 2, . . . , n) are selectively associated with a respective first exposure; at a second scan, data for raster lines (i+1, i+2, . . . n) are selectively associated with a respective second exposure and data for raster lines (n+1, n+2, . . . , n+i) are selectively associated with a respective first exposure; and, said respective first exposure for raster lines (i+1, i+2, . . . , n) is not equal to said respective second exposure for raster lines (i+1, i+2, . . . , n).