Canon PC940 Service Manual - Page 222

CHAPTER 8 ADF I. Detecting Original Jams The ADF is equipped with three jam sensors (PI1 through PI3) as indicated in Figure 8-123 to monitor the movement of originals. The movement of originals are checked at such times as programmed in the CPU on the ADF controller PCB; a jam is identified in relation to the presence of an original at each sensor. Table 8-103 describes the type of jam, condition of detection, and sensors involved. PI1 PI1: delivery sensor PI2: registration sensor PI2 PI3 PI3: original placement sensor Figure 8-123 Type of Original Jam and Condition of Detection Operation Type of jam Residual original Pickup Original present at start Separation delay Pick-up delay ADF open Delivery delay jam Delivery Delivery stationary jam Sensor PI1,PI2 PI1,PI2 PI2 PI2 MS1 PI1,PI2 PI1 Conditions When the 1st original is separated, the delivery sensor (PI1) turns on while the belt motor rotates for 300 ms or less or before the registration sensor (PI2) turns on. When the 1st original is picked up, the registration sensor (PI2) and the delivery sensor (PI1) turn on. When separation starts, the registration sensor (PI2) or the delivery sensor (PI1) are on. When separation starts, the registration sensor (PI2) does not turn on after 2 sec. When pickup starts, the registration sensor (PI2) does not turn off after feeding the original for about 500 mm. The ADF is opened while in operation. When delivery starts, the delivery sensor (PI1) does not detect an original that has been fed about 100 mm. After the registration sensor (PI2) has turned off, the delivery sensor (PI1) does not detect an original that has been fed for about 500 mm. During pickup, the delivery sensor (PI1) remains on even when the original is fed for 'length + about 60 mm'. Table 8-103 8-16 COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)