COPYRIGHT © 1999 CANON INC. CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)2. Multifeeder Last Sheet DetectionThe printer unit is capable of detecting the last sheet from the multifeeder. The feed-ing distance from the multifeeder tray paper sensor to the registration roller is short; assuch, if the last sheet was picked up during continuous printing, writing would start beforethe DC controller PCB identifies the absence of paper, requiring the printer unit to detectthe absence of paper before writing starts and, ultimately, to prevent soiling between thephotosensitive drum and the intermediate transfer drum.The last sheet is detected by monitoring the rotation of the last sheet detecting rollmounted to the multifeeder tray by the multifeeder tray last sheet sensor (P19).If two or more sheets of paper exist on the multifeeder tray, the last paper detectingroll will not rotate during pick-up operation. When the last sheet is picked up, however, thesheet will rotate the last sheet detecting roll, causing the output of the last paper sensorto change between ‘1’ and ‘0’. In response, the DC controller PCB will assume that thelast sheet has been picked up, and communicate the fact (absence of paper) to the print-er board*1 to stop writing the next image.*1 Reader controller PCB (when making prints with the reader unit installed).Figure 5-214CHAPTER 5 PICK-UP/FEEDING SYSTEM5-18Multifeeder pick-up rollerLast sheetMultifeeder tray last paper sensor (PS19)Last sheet detecting rollDownload free service manual at http://printer1.blogspot.com
