Detecting Jams - Canon NP6412 Service Manual

CHAPTER 5 PICK-UP/FEEDING SYSTEM
D.

Detecting Jams

The machine is equipped with three paper sensors used to find out the presence/absence of
copy paper and whether copy paper is moving properly.
• Vertical path roller paper sensor (PS4)
• Pre-registration roller paper sensor (Q751)
• Delivery sensor (PS3)
The presence/absence of a jam is checked with reference to the presence/absence of paper over
a specific sensor at such times as programmed in the microprocessor.
The machine keeps a record of the remaining number of copies to make or the copy mode
effective at time of a jam.
The microprocessor possesses the following seven types of no paper/jam detection sequence; if
any of its sensors detects copy paper at power-on, the machine will identify the condition as a jam.
Delivery roller
Fixing assembly
Cassette
1. Multifeeder Pickup Assembly (no paper, pickup delay jam)
If copy paper does not reach the pre-registration roller paper sensor within a specific period of
time in multifeeder mode, the condition will be identified as the absence of paper; the machine will
stop the main motor in about 1.5 sec, and indicate the Add Paper message.
If the pre-registration roller paper sensor detects copy paper during this 1.5 sec period (ap-
proximate), the machine will identify the condition as a pickup delay jam, and flash the Jam indica-
tor.
5-8
COPYRIGHT © 1999 CANON INC.
Photosensitive drum
Registration roller
Figure 5-109
CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Multifeeder pickup roller
PS4
Q751
Cassette
pickup roller
Vertical
path
roller