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DEVELOPING UNIT
[7] Toner Density Control
The toner density is controlled by the TDS (toner density
sensor), M35 (agitator screw), M10 (toner supply) and the CB
(control board).
1. Operation
a. Toner density detection
The TDS detects the density of the toner in the developing
unit using an L detection method, and outputs an analog
voltage signal that is proportional to the density to the CB.
The CB compares the detected voltage with the reference
voltage corresponding to the initial density of the devel-
oper, and judges the necessity of supplying toner.
b. Toner supply operation
M10 is driven by 24 V DC supplied from the DCPS (DC
power supply).
(1) When the power is switched ON
M35 (agitator screw) starts to rotate as soon as the
machine is switched ON, then after 4 minutes the toner
density is read. This density is compared with the initial
density of the developer, and if the density is low, toner
supply takes place.(recovered until its initial density)
24VDC
PGND
99-2
99-5
DCPS
M10 PLL
M10 DRIVE
M35 PLL
M35 DRIVE
TDS CONT
12VDC
TDS ANG
SGND
30-B11
30-B12
30-A6
30-A7
5-A5
5-A6
5-A7
5-A8
CB
M10
M35
TDS
TDS output voltage
2 V or lower
2 to 2.11 V
2.12 to 2.19 V
2.20 to 2.29 V
2.30 to 2.37 V
2.38 to 2.45 V
2.46 V or higher
Toner supply time
0 sec
0.24 sec
0.48 sec
0.72 sec
0.96 sec
1.20 sec
1.80 sec
2. Signals
a. Input signals
(1) TDS ANG (TDS → CB)
An analog voltage proportional to the toner density is
output.
(2) M10 PLL (M10 → CB)
[L] is output when M10 reaches the specified speed.
(3) M35 PLL (M35 → CB)
[L] is output when M35 reaches the specified speed.
b. Output signals
(1) TDS CONT (CB → TDS)
TDS output voltage adjustment signal
Output voltage adjustment: 4.9 to 9.8 V
(2) M10 CONT (CB → M10)
M10 drive control signal
Toner is supplied when M10 is ON.
[L]: M10 ON
[H]: M10 OFF
(3) M35 CONT (CB → M35)
M35 drive control signal
[L]: M35 ON
[H]: M35 OFF
(2) During a copy operation
The relationship between the TDS output voltage
(TDS ANG) and the toner supply time is as follows.
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