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OPERATIONS
AND
TIMING
b)
When
ACBON
=
'•The
AC
bias switch
circuit
goes OFF.
So
the output
of
the
square
wave
oscillator
goes
to
the T1
drive
circuit.
This
causes
the
AC
high-voltage transformer
to
generate
a
1300VAC
AC
bias,
which
is
supplied
to
the
developing
cylinder.
Also, the
output
of
the
AC
high-voltage
transformer
is
rectified
and
suppled
to
the
static
charge
eliminator (apprbx. 3.2
kV).
b.
Controlling
DC
bias
The
differential
amplifier
of
Figure 3-21
operates
when
DCBC
is
16V
or
below.
(The
range
of
DCBC
(analog)
is
6
to
16V,
as
set
by the
copy
density cursor
or
the
AE
system.)
I
—
>
Differential
amplifier
goes ON.
I-*
Variable pulse-width
oscillator
goes
ON.
L-»DC
high-voltage
transformer
goes
ON.
The
DC
bias
is
applied
to
the
developing
cylinder.
The
copy
density
knob changes
the
DC
component
of
the
developing
bias
as
shown
in
Figure
3-20.
COPY
DENSITY
lever
scale
«
,
,
,
(?)
,
,
.
P
-100
-200
-300
-400
-500
DC
bias
Figure 3-20
Changes
in
Development
Bias
(DC component) by
COPY
DENSITY knob
DCBC
6Vto16V
DC
component
of
developing
bias
-500V
to
-0V
DC
controller
PCB
High'-
voltage transformer
unit
(HVT)
Figure
3-21
COPYRIGHT©
1992
CANON
INC.
CANON
NP-1S50
REV.1
SEPT. 1992
PRINTED
IN
JAPAN
(IMPRIME
AU
JAP0N)
3-23
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