Canon PC980 Service Manual - Page 117

CHAPTER 4 IMAGE FORMATION SYSTEM A. Cartridge 1. Outline The machine's photosensitive drum, primary charging roller, developing assembly, and cleaner are housed in a single container referred to as a "cartridge." (You cannot disassemble the cartridge.) Developing blade Primary charging roller Light-blocking shutter Photosensitive drum Cleaning blade Drum cover shutter Developing cylinder Figure 4-201 a. Drum Cover Shutter If exposed to strong light for a long time, the photosensitive drum can develop photo memory, which can cause white spots or black bands on copies. To prevent photo memory, the machine is equipped with a drum cover shutter. Do not open the shutter unless absolutely necessary. It is designed to open when the cartridge is fit into the machine and the machine's top unit is closed. b. Light-Blocking Shutter When the cartridge is removed from the machine, light makes its way through the opening used to expose images. As in the case of the drum cover shutter, the light-blocking shutter is provided to protect the photosensitive drum from light. COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON) 4-23