Multi-beam drawing method using partially damaged light emitting devices and including spiral correction

摘要

In a multi-beam drawing method in which drawing is performed with a plurality of light-emitting devices (LDs), it is detected whether any LD is damaged. Of a plurality of partial LD lines obtained by partitioning at a damaged LD or LDs, the partial LD line including the largest number of LDs is selected as an effective LD line for use in drawing. Spiral correction is performed by dividing image data to be supplied to the LDs into a plurality of virtual small images parallel to the sub-scanning direction which are shifted in a reverse direction to the sub-scanning direction.