Canon PC720 Service Manual - Page 144

MI MECHANICAL SYSTEM V. CHARGING/DEVELOPING/CLEANING SYSTEM A. Cartridge 1. Outline The copier's photosensitive drum, primary charging roller, developing assembly, and clean- er are housed in a single container called cartridge. (You cannot disassemble the cartridge.) Developing blade Primary charging roller Light-blocking shutter Photosensitive drum Cleaning blade Drum cover shutter Developing cylinder Figure 4-501 a. Drum Cover Shutter If the photosensitive drum is exposed to strong light for a long period of time, the copies can come to show white spots or black bands; the drum cover shutter is provided to prevent such a problem. You should not open the drum cover shutter without good reason; it is designed to open when the cartridge is inserted into the copier and the copier's top unit is closed. b. Light-Blocking Shutter Light enters through the image exposure opening when the cartridge is removed from the copier; the light-blocking shutter is provided to protect the photosensitive drum from such light. 4 - 28 COPYRIGHT 1994 CANON INC. CANON PC72M40/7501170 REV.O AUG.1994 PRINTED IN JAPAN omPnimt AU JAPAN)