.,’ --
II. EXPOSURE SYSTEM
A. Varying the Reproduction
Ratio
The reproduction ratio in the direction of
the drum axis is varied by the lens drive sys-
tem and that around the drum, by the scan-
ner drive system.
The lens drive system holds a lens array
and changes the location of the lens and the
optical path length as shown in Figure 3-201
to vary the reproduction ratio in the direction
of the drum axis; the length of the optical
path is changed by moving the No. 4 and
No. 5 mirror units as shown in Figure 3-202.
The scanner drive system changes the
reproduction ratio around the drum by mov-
ing the No. 1 mirror faster (reduction) or
slower (enlargement) relative to the periph-
eral speed of the drum.
Reference:
1. In DIRECT, the speed at which the
No. 1 mirror is moved is the same as
the peripheral speed of the drum.
2. The length of the optical path is longer
in both REDUCE and ENLARGE than
in DIRECT.
p&h I*
length
Optical
path I4
length
Optical
path I*
length
Optical path: Li< L2, Li< L3
Figure 3-201
COPYRIGHT 0 1995 CANONINC. CANON NP6012lNP6012FiNP6212 AEV.1 SEPT.1995 PAlNTEDINJAPAN(IMPAIM~AUJAPON)
3-11
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