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F.
Document
Density Measurement
System
1. Outline
There
is an automatic
density adjust-
ment' (AE) system
which
adjusts the DC
component
of the developing
bias to suit
the density of the original. If the density of
the original is more or less uniform, the AE
function varies the DC component of the
developing bias to suit the density of the
original, so that copies of the correct den-
sity will be made.
2. Operation
The
scanner
moves
forward
approxi-
mately 70mm
past the leading edge of the
original and stops momentarily. The scan-
ning lamp goes ON for approximately one
second, the image density is read by the AE
sensor, and the sensor output is interpreted
by the DC controller. The DC controller then
adjusts the DC component of the develop-
ing bias accordingly.
A is the position of the
Approx. Approx.
AE sensor
25mm
25mm
[Approx. 65 mm
IBS
|A4 2
Approx.
i
30 mm
!
Approx.
i
70mm
va For reference:
B6 size
Approx.
1
28 mm
Note:
3. Reading Output of AE Sensor
The AE sensor consists of a photodiode
(Q702) and an operational amplifier
(Q70 1).
If the strength of light striking the photo-
diode is high, the output voltage (AE) of the
amplifier will be small, If the amount of light
is small, the output voltage will be large.
The DC controller reads the output at a
certain
time
after the
zero-cross
signal
(ZXDP)
is received
from the DC
power
supply.
Figure 3-23
ii PO
ihe"
eo.
Gok a he
7
=
a
|
WW
+
Wy
5V
l
24V
|
IVR
)
y
=
|
304
§
NS
!
AE
8
1
jQ702
Q701
1701-2
3315-9
5
|
5
|
4
l
2 | |
1
24V
i
|
AEBIAS
rh
|
ly701-1
J315-8|
vR303
7+
|
1
\
ss
eal
ieee
te
Bee Ye an eee, J
act
AE sensor
DC controller
Figure 3-24
3-22
COPYRIGHT © 1986 CAKOM INC,
CANON NP-1215 REV.O MAR. 1988 PRINTED IH JAPAN '(IMPAIME AU JAPON)
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