Canon NP6251 Service Manual page 122

CHAPTER 4 IMAGE FORMATION SYSTEM
a. AE Mode (CMAE) on the Copier's Side
During AE rotation (AER), the scanner is moved forward for 120 mm with the
scanning lamp on; the potential of the drum is then measured at four locations of the
copyboard (Figure 4-107) when the scanner is moved in reverse, and the measurements
are sent to the DC controller PCB.
The DC controller PCB computes the average based on these surface potential
measurements to determine the intensity of the scanner for copying.
b. AE Mode (RFAE) on the RDF Side
The RDF is equipped with an AE sensor in its original feeding path to measure the
density of originals while they are being moved.
The AE sensor is a reflecting type sensor in which two LEDs illuminate the original
and a photodiode measures the reflected light (Figure 4-108).
AE sensor 1 (S7) is used for left pick-up, while AE sensor 2 (S33) is used for right
pick-up (Figure 4-108).
4-8
COPYRIGHT © 1997 CANON INC.
120 mm
4 3 2 1
30 30 30 30 mm
Figure 4-107
AE sensor (S7)
Figure 4-108
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
AE sensor 2 (S33)