Paper Jam Detection - Canon LBP-1210 Service Manual

C. Paper Jam Detection
The following paper sensors are installed to detect paper presence and paper feed condition.
• Top of page sensor (PS402)
• Delivery paper sensor (PS401)
The CPU determines a paper jam by checking whether or not paper is present on the sensor at
the timing stored in the CPU.
When the CPU judges a paper jam, it stops print operation and notifies the jam to the inter-
face controller.
1. Pick-up delay jam
This printer performs the retry control to redress a pick-up delay jam caused by a pick-up error.
In this control, a pick-up operation is conducted a maximum of twice.
If the top of page sensor (PS402) dose not detect the leading edge of print paper within 1.4
seconds after the pick-up solenoid is turned ON in the first pick-up operation, the CPU tries
another pick-up operation. Still, if the PS402 does not detect the leading edge within 1.4 sec-
onds in this pick-up operation, the CPU determines a pick-up delay jam.
2. Pick-up stationary jam
If the top of page sensor (PS402) does not detect the trailing edge of the print paper within 4.6
seconds after detecting the leading edge, the CPU determines a pick-up stationary jam.
3. Delivery delay jam
If the leading edge of the paper does not reach the delivery paper sensor (PS401) within 2.1 sec-
onds after the top of page sensor (PS402) detects the edge the CPU determines a delivery delay
jam.
4. Wrapping jam
The CPU determines a wrapping jam under both the following two conditions: a) ten seconds
passed after the delivery paper sensor (PS401) detected the leading edge of print paper, and b)
the PS401 does not detect the trailing edge within 1.5 seconds after the top of page sensor
(PS402) detected the leading edge.
Note: In case of judging a wrapping jam, the CPU notifies the jam to the interface controller
as a delivery stationary jam.
5. Delivery stationary jam
If the delivery paper sensor (PS401) does not detect the leading edge of print paper within 2.2
seconds after the top of page sensor (PS402) detected the trailing edge the CPU determines a
delivery stationary jam.
6. Residual paper jam
During the initial rotation period, if the top of page sensor (PS402) or delivery paper sensor (PS
401) detects print paper, the CPU determines a residual jam.
Note: Automatic delivery
After the CPU received a print command from the interface controller, if the top of page
sensor (PS402) detects print paper prior to a pick-up operation, the CPU delivers the
paper, stopping driving the high-voltage power supply system, laser/scanner, and fixing
heater.
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