Jam Detection - Canon LBP-1120 Service Manual

B. Jam Detection
The following paper sensors are installed to detect whether paper is present and whether the paper is fed correctly:
• Paper top sensor (PS002)
• Paper delivery sensor (PS201)
The CPU determines a paper jam by checking for the presence of paper in the sensor at the timing stored in the CPU.
If the CPU determines that a jam has occurred, it stops the print operation and notifies the jam to the interface
controller.
1. Pickup delay jam
When the paper does not reach the paper top sensor (PS002) after the pickup solenoid (SL001) has been turned ON
three times within the specified period of time (includes two pickup retry operations.)
2. Pickup stationary jam
When the paper top sensor (PS002) cannot detect the trailing edge of the paper within 6.7 seconds after detecting the
leading edge of the paper.
3. Delivery delay jam
When the paper delivery sensor (PS201) cannot detect the leading edge of the paper within 2.7 seconds after the paper
top sensor (PS002) detects the leading edge.
4. Wrapping jam
When the paper delivery sensor (PS201) detects the trailing edge of the paper within 2.0 seconds after the paper top
sensor (PS002) detects the trailing edge.
5. Delivery stationary jam
When the paper delivery sensor (PS201) detects no paper-out within 2.7 seconds after the paper top sensor (PS002)
detects the trailing edge of the paper.
6. Initial residual paper jam
When the paper delivery sensor (PS201) or the paper top sensor (PS002) detects paper in the initial rotation period.
Note: Automatic paper delivery
• After the output of a pickup command, if the paper top sensor detects the presence of paper before
the pickup operation, the CPU immediately stops the high-voltage power supply, laser/scanner, and
fixing unit, and delivers the paper.
• The CPU will assume the presence of a start-up residual jam if the paper sensor (PS002) detects
print paper after the power has been turned on or when a software reset has been executed by the
interface controller.
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