Main Unit Theory of Operation Toner Cartridge / Hopper
2-17
II Composition/Operation
4.2.4 Toner empty condition detection
• A toner empty condition is detected by the LED and toner level sensor mounted on the
Toner Level Sensor Board (PWB-D) provided in the machine.
• Light emitted from the LED travels through the light guiding path and is guided into the
Toner Cartridge.
• The toner level sensor detects the intensity of the transmitted light guided through the
light guiding path from the inside of the Toner Cartridge. The toner level is thereby esti-
mated.
• To ensure correct detection of the intensity of transmitted light by the toner level sensor, a
cleaning sheet is provided that cleans the window in the light guiding path periodically.
• Detection start timing
1. When the Developing Unit is driven evenly
2. LED steady light is stabilized
3. When the above two conditions are met, the machine starts a toner empty detection
sequence. Detection control is, however, interrupted during registration correction and
gamma correction, in which it is not possible to acquire output values of the toner level
sensor.
• <Empty decision>
1. A sequence is started for detecting a toner empty condition when a toner near-empty
condition is detected.
2. The machine determines that there is a toner empty condition when the toner level sen-
sor output value remains below a predetermined value and if the following event is
detected a predetermined number of consecutive times: the output value of the toner
level sensor remains a predetermined value or lower for more than a predetermined
period of time.
3. The consecutive detection count is retained even when power is turned OFF.
• <Resetting empty condition>
A toner empty condition is reset when a new Toner Cartridge is detected.
4138to2012c2
4138to2012c1
LED Sensor
Light Guiding Path
Cleaning Sheet
Cleaning Sheet
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