Canon Laser Shot LBP-5100, Service Manual

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Chapter 2
2-19
If the Bk toner absence is detected, the machine will stop working.
If the color toner absence is detected, only monochrome print can be done.
2.4.4.5 Detecting the Level of Toner
0010-7907
LBP5000 / LBP5100
The machine monitors the level of toner inside the cartridge.
To find out how much toner remains, the DC controller PCB refers to the time it takes for light to move through the cartridge while printing is under way.
The memory controller PCB is mounted to the back of the toner cartridge, equipped with a light-emitting segment (LED) and a light-receiving segment (photodi-
ode). When printing starts, the DC controller turns on the LED. The light from the light-emitting segment moves along the light guide to move into the toner case,
through the toner case, and along the opposite light guide to reach the light-receiving segment.
F-2-23
When there is much toner inside the toner case, the light is blocked by the toner, not reaching the light-receiving segment. On the other hand, when there is little
toner, the light moves through to reach the light-receiving segment. The DC controller PCB identifies the level of toner remaining inside with reference to the period
of time during which light hits the light-receiving segment while the stirring plate makes a single rotation.
The DC controller communicates the level of toner it has identified (as being sufficient, being insufficient, and being absent; 3 levels) to the video controller. If the
light-receiving segment continuously receives light while the stirring plate rotates 5 times, the DC controller will identify the condition as indicating that the toner
level sensor is out of order, thus stopping the printer engine and, at the same time, indicating 'E024' in the status window.
2.4.5 Transfer Unit
2.4.5.1 ETB Unit
0010-6064
LBP5000 / LBP5100
The ETB unit serves to move print paper and also transfer toner to the print paper.
The following is an outline diagram of the ETB unit:
Toner le vel is high Toner le vel is lo w
Light
receiver
Light
emitter
Light
receiver
Light
emitter