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COPYRIGHT
©
1998 CANON INC. CANON NP7161/NP7160 REV.0 AUG. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
3–1
CHAPTER 3 EXPOSURE SYSTEM
I. OUTLINE OF OPERATION
A. Changing the Reproduction Ratio
The reproduction ratio in the axial direction of the photosensitive drum is varied by the lens
drive system and the mirror drive system, and that in the peripheral direction of the
photosensitive drum is changed by the scanner drive system.
The lens drive system uses a lens array and, as shown in Figure 3-101, the lens position and
the optical length are varied to change the reproduction ratio in the axial direction of the
photosensitive drum.
The optical length is varied, as shown in Figure 3-102, by changing the location of the No. 4/
No. 5 mirror unit.
The scanner drive system moves the No. 1 mirror relatively faster (in Reduce) or slower (in
Enlarge) than the photosensitive drum (peripheral speed) to change the reproduction ratio in the
peripheral direction of the photosensitive drum.
Note:
1. In Direct, the speed of the No. 1 mirror is made identical to the peripheral speed of the
photosensitive drum.
2. In both Reduce and Enlarge, the optical length is longer than in Direct.
Direct
Reduce
Enlarge
Optical length
F
F
F
F'
F'
F'
L3
Optical length
L2
Optical length
L1
Figure 3-101