| 摘要 |
PURPOSE:To make respective main scanning lines uniform in length by a method wherein correction clocks for respective reflecting surfaces obtained by measuring a laser light main scanning time for every reflecting surface of a polygon mirror are randomly dispersed in a printing clock using a random circuit. CONSTITUTION:Based on a detection signal from a mirror sensor part 35 detecting the rotation of a polygon mirror 6, respective reflecting surfaces 71-76 are discriminated. Counters 341-344 count a time difference between a detection signal outputted from a start sensor part 12 and that from an end sensor part 16 by the pulse of a reference clock A, whereby a main scanning time is measured for each of the reflecting surfaces 71-76. Then, in a printing clock B corresponding to the reflecting surface 7 conducting a short main scanning, count enable signals are inserted by the predetermined number by a count enable signal generator 36 and, furthermore, inserting timings are made random by a random circuit 37 and a shift circuit 38, and a correction printing clock D is formed. In this manner, a laser spot scanning and traveling on a photosensitive body can be made uniform in main scanning speed. |
