Measuring The Density Of Originals - Canon NP6512 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
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.
Scanning lamp
+24V
-
+
+24V
-
+
AE sensor
4-18
COPYRIGHT © 1999 CANON INC.
J601 J107
-3 -2
+24V
AEREF
-
+5V +
-2 -3
AE
+24V
-
+
DC controller PCB
Figure 4-111
CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
VR103
(Q101)
+5V
VR102
Developing
cylinder
Photo-
sensitive
drum
(Q900)
Developing
DCON signal
Serial
communi-
cation
Composite power
supply PCB