Canon NP6621 Service Manual page 127

4. When the registration sensor turns ON, the set-back roller and the duplexing unit outlet roller rotate
clockwise to pick up the second copy paper.
COPYRIGHT © 1998 CANON INC.
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Separation
sensor
Figure 3-425
CANON NP6621 REV.0 FEB. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
OPERATIONS AND TIMING
Photosensitive
Registration sensor(PS6)
drum
Slip roller
3–71