Canon EF-9, Service Manual

Page: 21 / 54

B. Multi-feed Prevention Mechanism
This envelope feeder utilizes the separation roller method to prevent feeding multiple envelopes.
The upper separation roller is driven by the motor via a torque limiter. The upper separation
roller is imparted with rotational force in the direction of the outlined arrow. However, as the
upper separation roller, envelope and lower separation roller are in contact with each other, the
rotational force of the lower separation roller is transmitted to the upper separation roller via the
envelope and the upper separation roller rotates in the direction of the solid arrow (as shown in
the middle figure of Figure 2-2-3).
When two or more envelopes are fed simultaneously, low friction between the envelopes
results in weak rotational force being transmitted to the upper separation roller. The upper sep-
aration roller, therefore, rotates with its own rotational force, which is in the opposite direction
to the pick-up direction (shown by the outlined arrows in Figure 2-2-3).
Any extra envelopes are returned to the feeder while only one is sent into the printer.
Figure 2-2-3
2 - 5
CHAPTER 2
Normal
Multifeed
Pick-up roller
Upper separation roller
Lower separation roller
Envelope
Driving force transmitted from the pick-up motor
through the torque limiter.
Driving force transmitted
from lower separation
roller