Canon FINISHER - D1 Service Manual page 77

2. Detecting the Surface of Paper on the Tray
The tray B paper sensor used to detect the surface of paper on the tray consists of two sensors:
one serving as a light-emitting unit and the other, light-receiving unit.
The light-receiving side possesses three cells:
The bottom light-receiving cell is used when no paper exists on the tray. The output of the upper
two cells changes if either is locked by paper on the tray. By referring to either of the two light-
receiving cells, the machine will be able to identify the presence of paper even its trailing edge curls
upward.
Paper
COPYRIGHT © 1999 CANON INC.
Light-emitting
Tray B
Figure 2-602
CANON FINISHER - D1 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 2 OPERATIONS
Stack delivery roller
Light-receiving
(front)
2-51