Separation Mechanism; Separation Charging Mechanism; Outline; Correcting The Output To Suit The Environment And The Drum Surface Potential - Canon iR6570 series Service Manual

7.9 Separation Mechanism

7.9.1 Separation Charging Mechanism

7.9.1.1 Outline

The following items are associated with the separation charging control system:
1. controlling the constant current of the DC bias
2. controlling the constant voltage of the AC bias
3. correcting the output to suit the environment and drum surface potential (fuzzy control)
The following shows the construction of the separation charging control system:
The following signals are associated with the separation charging control mechanisms:
[1] Separation charging leakage detection signal; if the current is too high or too low, '0'.
[2] Separation charging current control signal; used to control the DC bias current and the AC bias voltage generated by the high-voltage PCB.
[3] Separation charging remote signal; turns on/off the separation current output.

7.9.1.2 Correcting the Output to Suit the Environment and the Drum Surface Potential

The separation current output is optimized to suit the environment (i.e., reading of the environment sensor) and the deposit of toner (either of 3 levels; low,
average, high, as determined by the count of black pixels).
[1] In a low humidity environment, paper tends to become dry, thus tending to collect charges (high resistance). The output is decreased.
[2] If the drum surface potential is low, the output is increased to prevent separation faults.
[3] If the drum surface potential is high, the current level is lowered to prevent re-transfer.
SERVICE MODE:
COPIER> OPTION> BODY> FUZZY (turning off/on fuzzy control)
0: enable fuzzy control (default)
1: low humidity mode (for higher pre-transfer charging current than normal)
2: normal humidity mode
SEPARATE-LEAK-
DETECT [1]
HVT-AC [2]
HVT_SEPARATE [3]
In a low humidity environment, paper tends to
become dry, thus easily collecting charges
(high resistance); to remedy the fact,
the output is lowered.
Low humidity
Separation
charging wire
AC+DC
F-7-29
If the toner deposit is low, the output
is increased to prevent separation faults.
Toner deposit low
Toner deposit average
Toner deposit high
High humidity
If the toner deposit is high, the current
level is lowered to prevent re-transfer.
F-7-30
Chapter 7
0009-4113
0009-4115
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