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OPERATIONS
AND
TIMING
II.
EXPOSURE SYSTEM
A.
Changing
the
Reproduction
Ratio
The
reproduction
ratio
across
the
drum
is
varied
by changing
the position
of
the
lens.
It
is
moved
by
the
lens drive
system.
The
reproduction
ratio
around
the
drum
is
varied
by
changing
the
speed
of
the scanner.
Figure 3-9
shows how
the
position
of
the
lens
is
varied
to
change
the reproduction
ratio
across the drum.
DIRECT
REDUCTION
£
ENLARGEMENT
(
Figure
3-9
B.
Lens
Drive
System
1.
Outline
The
lens
is
moved
by
the
scanner motor
(M2).
Normally, the coupling
gear
is in
its
upper
position,
and connects
the
scanner
motor
to
the
scanner
drive
capstan.
To
move
the
lens,
the lens solenoid (SL2)
goes ON,
causing the
coupling
gear
to
disengage from
the
scanner capstan gear
and engage
with
the
lens
capstan
gear.
The
lens
is
a
"floating
element"
type.
In
operation, the
relative
position
of
lens
elements
(individual
lenses)
changes, and
the
focal
length
changes
as a
result,
but the
changes
are
to
optimize
lens
sharpness
for
each
reproduction
ratio,
not
to
make
the lens function
as a
zoom
lens.
(The
lens
should
not
be
dismantled.)
When
the
scanner motor
rotates
(CW),
the lens
will
be
moved
to
the
left
(for
ENLARGEMENT)
by the capstan
and
cable.
When
the cassette size
is
changed
or
when
the copier
is in
the
REDUCE
mode,
the
blank
exposure
shutter
moves
in
relation to
the distance
over
which
the lens
travels,
thereby blanking
out the width
corresponding
to
the reproduction
ratio;
see
p.
3-28.
The
DC
controller
indicates 'E210'
on
the
control
panel
in
response
to
an
error
in
the
lens drive
system.
The
scanner
drive
system changes
the
reproduction
ratio
around
the
drum
by
varying the
speed
at
which
mirror
1
moves
relative
to
the peripheral
speed
of
the
drum.
(The scanner
is
mirror
1
plus the
scanning
lamp.)
The
mirror
speed
is
faster
than the
drum
peripheral
speed
for
REDUCTION
and
slower
for
ENLARGEMENT
Note;
r
:.,.,
;M«
The
relative
;
position
of
the
mirrors
is
not
Changed
to
vary the reproduction
ratio.
S;
2l
For
DIRECT
copying, the
speed
of
the
mirror
is
the
same
as the
peripheral
speed
of
the
drum.
COPYRIGHT©
1992
CANON
INC.
CANON
NP-1550
REV.O
JAN.
1992
PRINTED
IN
JAPAN
(IMPRIME
AU JAPON)
3-11
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