COPYRIGHT © 1999 CANON INC. CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)5. Cassette 1 Last Sheet DetectionThe printer unit is capable of detecting the last sheet from the cassette 1. The feed-ing distance from the cassette 1 paper absent 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 cassette 1 last sheet sensor (PS29) is a reflecting type sensor, and consists of alight-emitting section and a light-receiving section. In the presence of paper, the light fromthe light-emitting section will be reflected by the paper to reach the light-receiving sec-tion. In the absence of paper (after the last sheet has been picked up), on the other hand,the light from the light-emitting section will pass through the machine’s inside, not reach-ing the light-receiving section.In response, the DC controller PCB will assume that the last sheet has been pickedup, and communicate the fact to the printer board*1 to stop writing of the next image.*1Reader controller PCB (when making prints with the reader unit installed).Figure 5-212CHAPTER 5 PICK-UP/FEEDING SYSTEM5-15Last sheet Pick-up rollerCassette 1 last sheet sensor (PS29)One Sheet Exists in the Cassette 1No Sheet Exists in the Cassette 1Download free service manual at http://printer1.blogspot.com
