CHAPTER 3 EXPOSURE SYSTEM
A. Original Size Detection
1. Outline of Detection
The machine is equipped with auto paper selection and auto ratio selection
functions, which necessitate the identification of the size of originals.
As many as four original detection circuits are mounted under the copyboard glass
(Figure 3-401). The outputs of these circuits are checked by the DC controller when the
copyboard cover is closed so as to identify the original as being A3, B4, A4, or B5.
An original detecting circuit consists of an LED which emits light against the original
and a phototransistor which checks the light reflected by the original for output to the DC
Original detection signal 2
DC controller PCB
COPYRIGHT © 1997 CANON INC.
Original detection circuit 3
Original detection signal 1
Copyboard cover detection signal 1
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)