COPYRIGHT © 1999 CANON INC. CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)F. Checking the Presence/Absence of a Color Toner CartridgeThe presence/absence of a color toner cartridge is detected by the cartridge sensor(PS1901C), which consists of a light-emitting section and a light-receiving section.When the color toner cartridge in question is set, the light from the light-emitting sec-tion is reflected by the cartridge and reaches the light-reflecting section; in the absenceof the cartridge, on the other hand, it enters the machine, not reaching the light-receiv-ing section. The DC controller PCB identifies the condition as the absence of the colortoner cartridge, and communicates the fact to the printer board*1 to stop the machine.The machine checks the presence of cartridges when the power is turned on or whenthe various covers have been opened/closed.*1 Reader controller PCB (when making prints with the reader unit installed).G. Checking the Level of Black Toner and thePresence/Absence of the Black Toner CartridgeThe level of black toner is checked by the antenna sensor inside the black toner car-tridge. The output of the toner antenna (toner level detection signal) is sent to the DC con-troller PCB through the high-voltage PCB, which checks on the signal at such times asblack developing AC bias is applied to the black developing cylinder.If the level is below a specific value, the DC controller PCB communicates theabsence of black toner to the printer board*1.The presence/absent of the black toner cartridge is checked by a switch (black tonercartridge detecting switch SW644) inside the copier.*1 Reader controller PCB (when making prints with the reader assembly installed).CHAPTER 4 IMAGE FORMATION SYSTEM4-17Download free service manual at http://printer1.blogspot.com
