Toner Density Control - Konica Minolta 7020 Service Manual

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Toner Density Control

DCPS
Toner density is controlled by the TDS (toner density
sensor), M4 (toner supply motor 1), M10 (toner supply
motor 2: other than 7020/25/30) and the PRDB (printer
driver board).
1. Operation
a. Toner density control
The TDS uses L detection to detect the toner density
in the developing unit, and outputs to the PRDB an
analog signal corresponding to the detected density.
The PRDB determines whether toner supply is
necessary by comparing the detected value against
the developer's initial density.
b. Supply of toner to the developing unit
M4 and M10 (other than 7020/25/30) are stepping
motor running on 24VDC. Drive time is controlled by
the PRDB.
24VDC 24VDC
24VDC 24VDC
PGND PGND
PGND PGND
SGND
SGND M3 LD
5VDC M3 CW/CCW
M3 CLK
12VDC
M3 CONT
SGND
SGND
5VDC
A
A
B
B
24VDC
24VDC
A
A
B
B
24VDC
24VDC
Other than 7020/25/30
TDS CONT
12VDC
TONER ANG
SGND
SGND
PS1
5VDC
PRDB
(1) When the power switched ON
Following power on, M1 (main motor) turns the agitator
screws, and after a predetermined time interval the TDS
reads the toner density. The PRDB compares the
density detected by TDS with the developer's initial
density. If the detected density is low, M4 and M10
M3
(other than 7020/25/30) comes on and supplies toner
until the proper density level is restored.
(2) During a copy operation
The following table shows the relation between TDS
output voltage and toner supply time.
M4
7020/25/30/35
4
TDS output voltage
≤ 2.00 (2.01) V
M10
2.01 to 2.05 (2.04) V
2.06 (2.04) to 2.09 (2.08) V
2.10 (2.08) to 2.13 (2.12) V
TDS
2.14 (2.12) to 2.17 (2.19) V
2.18 (2.19) to 2.21 (2.35) V
PS1
≥ 2.22 (2.35) V
Parenthesized values are for the 7035
7022/7130/7135
4
TDS output voltage
≤ 2.00 V
2.01 to 2.07 V
2.08 to 2.15 V
2.16 to 2.22 V
2.23 to 2.30 V
2.31 to 2.38 V
≥ 2.39 V
2. Signals
a. Input signal
(1) TONER ANG (TDS −> PRDB)
Outputs an analog voltage corresponding to the toner density.
b. Output signals
(1) TDS CONT (PRDB −> TDS)
TDS output voltage adjustment signal.
Output range: 3 to 8 V
(2) M4 A, A, B, B (PRDB −> M4)
M4 drive control signals.
(3) M10 A, A, B, B (PRDB −> M10)
M10 drive control signals. (
2-G-3
DEVELOPING UNIT
Replenishment Time
0 sec.
0.24 (0.10) sec.
0.48 (0.20) sec.
0.72 (0.30) sec.
0.96 (0.40) sec.
1.20 (0.50) sec.
1.80 (0.70) sec.
Replenishment Time
0 sec.
0.10 sec.
0.20 sec.
0.30 sec.
0.40 sec.
0.50 sec.
0.70 sec.
)
other than 7020/25/30