Drum Cartridge Memory - Canon CP660 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
B.

Drum Cartridge Memory

The drum cartridge memory (EEPROM) contains two areas: ROM area and RAM
area. The ROM area retains an ID code specific to the drum cartridge, and is used exclu-
sively for reading. The DC controller PCB reads the ROM area of the drum cartridge
when the power switch is turned on or the cover is closed to check if the correct cartridge
is set.
The RAM area allows both reading and writing, and the DC controller PCB reads from
the drum cartridge memory at specific timing to check the presence/absence or the life
of the drum cartridge.
The timing at which the DC controller PCB reads and writes data stored in the RAM
area of the drum cartridge is as follows:
Reading
• When the power switch is turned on.
• When the cover is closed.
Writing
• When the power is turned off.
• When the cover is opened.
• At the end of printing (in the case of continuous printing, at the end of continuous
printing, or at the end of jam removal).
The copier remembers a fault, if any, in the drum cartridge at time of reading/writ-
ing. If writing fails (or reading fails three times consecutively), i.e., an error check
sum, the DC controller PCB communicates the fact to the printer board*
cartridge memory fault.
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* Reader controller PCB (when making copies with the reader unit installed).
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COPYRIGHT © 1999 CANON INC.
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CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
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as a drum