Canon iR C3380 series Service Manual page 285

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.
Increasing the fixing
feeding speed
Same as process speed
Decreasing the fixing
feeding speed
For plain paper
For heavy paper / OHT
The feeding speeds at the sensor ON / OFF are shown as below.
Process speed
Arch sensor ON
(Increasing the fixing feeding speed)
Detection of large arch
PS16
F-8-27
At the point where the leading edge of
paper reaches the fixing nip
During arch control
PS16 detects large arch
(Approx. 510 msec for A4) (Approx. 108 msec for A4)
Only detection of small arch by PS2
F-8-28
T-8-11
Constant speed
143.0 mm/s
146.8 mm/s
Detection of small arch
PS2 detects small arch
Switch PS16 / PS2 due to the
distance of paper delivered from fixing
- LTR or less:
Trail edge of paper 20%
- More than LTR:
Trail edge of paper 50%
Half speed
71.5 mm/s
73.4 mm/s
PS2
At the point where the
trailing edge of paper
has passed the secondary
transfer roller
1 / 4 speed
35.8 mm/s
36.7 mm/s
Chapter 8
8-23