CHAPTER 3 EXPOSURE SYSTEMCOPYRIGHT © 1999 CANON INC. CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)3-2Figure 3-102DirectOptical lengthReductionOptical lengthEnlargementOptical lengthOptical length: L1 < L2, L1 < L3L3L2L1FFFF'F'F'B. Varying the Reproduction RatioThe reproduction ratio in the drum axial direction (main scanning direction) is varied by thelens drive system, and that in the drum peripheral direction (sub scanning direction) is changed bythe scanner drive system.In the lens drive system, the positions of the fixed focal point lens and the No. 4/5 mirror arechanged to vary the reproduction ratio.In the scanner system, the relative speed of the No. 1 mirror mount is made higher (for reduc-tion) or lower (for enlargement) than the drum peripheral speed.
