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I
OPERATIONS
AND
TIMING!
H.
Blanking
1.
Outline
The
area
of
the
drum between
the
trailing
edge
of
one
copy and
the leading
edge
of
the next
would
normally
act
as
an
all
black
area
and
attract
toner
if
a
preventive
measure were
not taken.
This
measure
is
to
switch the primary
corona
OFF
and
the
primary
corona assembly
grid
wire bias
ON
(There
is
no
blank exposure;
see page
3-
22.)
When
the
copy
(cassette) size
is
a non-
default size or
when
the copier
is
in
the
REDUCE
mode,
the
light
from
the pre-
exposure lamp
is
directed to the
photosensi-
tive
drum
by
way
of
the
reflecting
plate
to
prevent
adhesion
of toner;
the
blank expo-
sure
shutter
is
moved
to
open
the
exposure
slit
making use
of
the
movement
of
the
lens.
Movement
of
the
Blank
Exposure
Mechanism
When
the copier
is
switched
ON,
the lens
first
moves
in
the
direction
of.
enlarge-
ment and
then
returns
to
the
home
posi-
tion.
:
Next, the lens
moves
in
the
direc-
tion of
reduction
for
blank
exposure up
to
a
point that
corresponds
to
the cassette
size.
At the
time,
the
blank solenoid
goes
ON,
and
the blank
exposure
shutter
moves
in
the
direction of
the
arrow
by
the force
of
the
spring.
Blank exposure
shutter
(Front),
Figure 3-29
*<#%
Reflector
'€\
Pre-exposure
lamp
Blank exposure
shutter
Front
Reflector
Figure 3-28
3-28
COPYRIGHT©
1992
CANON
INC.
CANON
NP-1550
REM
JAN. 1992
PRINTED
IN
JAPAN
(IMPRIME
AU
JAPON)
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