6Toner Level Detection; Toner Level Detection - Canon iR4570 Series Service Manual

Chapter 7
does not detect the "presence of toner," the machine will assumes that the toner cartridge has not been replaced
and cause the toner cartridge motor to stop.

7.8.6 Toner Level Detection

iR2270 / iR2870 / iR3570 / iR4570
Detecting the Level of Toner Inside the Sub Hopper
The machine checks the level of the toner sensor located inside the sub hopper every 100 msec, and will assume the
presence of toner inside the sub hopper if the sensor goes on twice or more continuously (200 msec or more).
If the machine detects the absence of toner 100 times or more (10 sc or more) as the result of its check on the sensor
level made every 100 msec, the machine will assume that there is no toner inside the sub hopper.
The machine executes the foregoing detection at all times regardless of the state (on or off) of the main motor and
the developing clutch.
Detecting the Level of Toner Inside the Developing Assembly
1. The machine samples the output of the toner level sensor located inside the developing assembly every 100 msec
(only if the developing clutch is on).
2. The machine uses a period of 1.5 sec (15 times; cumulative sampling of periods when the clutch is on) as the unit
of measurement: if the presence of toner is detected 3 times or more, it will assume that there is toner inside the
developing assembly; if the presence of toner is detected less than 3 times, on the other hand, it will assume that
there is no toner inside the developing assembly.
However, in the case of the iR3570/iR4570 Series machines, the drive of the main motor is controlled to 2 different
speeds, and the toner inside the developing assembly is driven by the main motor (using a clutch), requiring a
switchover of methods of detection as follows:
Normal Speed Mode
The machine uses a period of 1.5 sec (25 times; cumulative sampling of periods when the clutch is on) as the unit of
measurement: if the presence of toner is detected 3 times or more, it will assume that there is toner inside the
developing assembly.
Low-Speed Mode
The machine uses a period of 2.5 sec (42 times; cumulative sampling of periods when the clutch is on) as the unit of
measurement: if it detects the presence of toner 5 times or more, it will assume that there is toner inside the
developing assembly.
The machine converts the number of samplings and the number of times toner detection has been executed when
switching over methods of detection. (The conversion is based on the speed-to-amount relationship.)
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