Canon Color iR C3480 Service Manual page 314

Chapter 8
PS2: Arch sensor
PS16: Arch sensor 2
M3: Fixing motor
3. Control Sequence
The sequence of arch control is shown as below.
a. Starting arch monitoring
Start arch monitoring from the point where the leading edge of paper enters fixing (the point of reaching the fixing nip).
b. Detection of the arch level
Two arch sensors detect the arch level.
- Arch sensor 2 (PS16): Detects large arch (sagging)
- Arch sensor (PS2): Detects small arch (sagging)
Reference:
This machine has two different sensors to detect large and small arch respectively to prevent noise and faulty image.
If there is large arch when a paper passes through the secondary transfer roller, the paper with large arch will straighten and noise occurs. If a paper hits somewhere,
faulty image (including soiled paper edge, etc) may occur.
To prevent this symptom, make the arch level of a paper smaller before passing through the secondary transfer roller so that the paper passes through the secondary
transfer roller without a large arch.
c. Speed control for the fixing motor (M3)
Control the fixing motor (M3) according to ON / OFF of the arch sensor (PS2) and the arch sensor 2 (PS16) to change the feeding speed.
In the former part of the control, keep the arch level large while the arch sensor 2 (PS16) detects large arch. In the latter part, keep the arch level small while the
arch sensor (PS2) detects small arch.
In both sensors, increase the fixing feeding speed when the sensor is ON (the arch level becomes larger). Decrease the fixing feeding speed when the sensor is OFF
(the arch level is smaller). This control keeps the arch level optimum.
For heavy paper and OHT, the arch sensor (PS2) usually controls only small arch.
There is no arch control for envelope.
8-32
PS16
PS2
F-8-26
Detection of large arch
PS16
F-8-27
M3
FUSE_M_XA
FUSE_M_A
FUSE_M_B
FUSE_M_XB
LOOP_SNS
DC Driver
LOOP2_SNS
Detection of small arch
DCON
PS2