Canon PC920 - Measuring Original Density (AE)

CHAPTER 4 IMAGE FORMATION SYSTEM
COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON) 4-16
Figure 4-113
Scanning lamp
+24V
+24V
+24V
+24V
+5V
+5V
VR102
VR103
J601
-3
J107
-2
AEREF
AE
-2 -3
-
+
-
+
-
+
-
+
Photo-
sensitive
drum
Developing
cylinder
(Q101)
(Q900)
Developing
DCON signal
Serial
communi-
cation
AE sensor
DC controller PCB
Composite power
supply PCB
Microprocessor
Microprocessor
F. Measuring the Density of Originals
1. Outline
The machine is equipped with an auto density adjustment (AE) mechanism designed to control
the DC component of the developing bias.
The AE mechanism enables production of copies free of fogging as long as the original is more
or less uniform in density by varying the DC component of the developing bias according to the
density of the original.