| 摘要 |
PROBLEM TO BE SOLVED: To reduce the scale of a circuit for controlling the driving of a plurality of motors for turning a plurality of scanning mirrors, respectively. SOLUTION: Detection signals HB, HM, HC and HY of a laser beam being scanned by a plurality of polygon mirrors are counted by counters CB, CM, CC and CY over a predetermined time. The counts are selected one by one by means of a selector 125 and inputted to a subtractor 127. The subtractor 127 subtracts a reference value from the counts to generate error data VB, VM, VC and VY which are stored in registers R1B, R1M, R1C and R1Y. Frequency of a clock for driving the plurality of polygon mirrors is then corrected based on the error data VB, VM, VC and VY. |
