Canon GP215 Service Manual page 178

3. OPERATIONS AND TIMING
The fixing film sensor (PS2) is located at the
edge of the film to detect the position of the fixing
film.
The rear (sensor side) of the fixing film has a
notch as shown in Figure 3-643 so that the fixing
film sensor repeats turning ON and OFF.
Normally, the sensor remains ON and OFF for
the same period of time when the fixing film is
centered.
When the fixing film starts to move to the rear,
the sensor will tend to remain ON longer than
OFF; if the film starts to move to the front, the
sensor will tend to remain OFF longer than OFF.
(See Figure 3-644.)
The DC controller checks the ratio between
ON and OFF periods of the sensor to correct the
position of the fixing film.
5
Unit; mm
Fixing film
(rear)
(front)
Figure 3-643
OFF
ON
Normal ON
OFF
ON
To rear
OFF
ON
To front
OFF
Figure 3-644
3–124
COPYRIGHT © 1996 CANON INC.
Tension roller
Drive roller
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
The fixing film motor (M5) is used to correct
the position of the fixing film.
When displacement of the fixing film is detect-
ed, the DC controller rotates the fixing film motor
to move the rear of the tension roller up and down,
thereby moving the fixing film to the center and
correcting the displacement.
If the fixing film has become replaced to the
rear, the tension roller is moved down to return
the fixing film to the front.
If the fixing film has become displaced to the
front, the tension roller is moved up to return the
fixing film to the rear.
These operations are executed as necessary
to control the position of the fixing film.
If the film has become displaced so much that
the correction mechanism cannot control it, 'E007'
will be indicated. (See the Service Handbook.)
Fixing film motor (M5)
Displaced to the front
Displaced to the rear
Figure 3-645