Ricoh FT8680, Service Manual

Page: 75 / 389

7.5 TONER END DETECTION
7.5.1 Toner Near End Detection
Toner near end is detected by measuring physical amount of toner remaining
in the toner tank by the following mechanism.
The toner near end feeler [A] has a magnet [B] and is installed on the toner
mixing vane drive shaft [C]. The toner near end sensor [D] is located
underneath the toner tank (outside) and has the sensor actuator [E] with a
magnet. When the toner tank has enough toner, the toner near end feeler
does not lower due to the resistance of toner.
When the remaining toner amount in the toner tank becomes below
approximately 250 grams, the near end feeler lowers and repulses the
sensor actuator by the magnet’s repulsion force. This actuates the toner near
end sensor. When the main PCB senses the toner near end sensor actuation
three times in a row, the toner near end condition is displayed on the CRT
screen to let the operator know to replace the toner cartridge. In the toner
near end condition, copies can be made until the toner end is detected by the
ID sensor.
[C]
[B]
[A]
[D]
[E]
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31 July 1995 TONER DENSITY DETECTION AND SUPPLY
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