Sharp FO 4400 - B/W Laser - All-in-One, Руководство по обслуживанию

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FO-4400U
FO-CS1
3 – 6
Fig. 9
Fig. 10
10. IMAGE TRANSFER
10-1. Overview
· Image transfer is the process of transferring the toner image created
on the PC Drum in the developing process to paper.
· Roller image transfer is used instead of corona image transfer as the
image transfer method.
· In roller image transfer, there is little generation of ozone due to corona
discharge. Also, there is no blur of toner because the paper is always
pressed by the PC Drum and the Image Transfer Roller.
· When cleaning the Image Transfer Roller and before printing, reverse
bias is applied.
· The residual electric potential on the paper is dissipated via a dis-
charge needle.
PC Drum
Paper
Image Transfer Roller
PC Drum
Paper
Image Transfer
Roller
Image Transfer Bias Reverse Bias
Discharge Needle
11. FUSING
11-1. Overview
· The toner image transferred onto the paper is securely fixed to the
paper.
· A heat roller system is used as the fusing system. The toner image is
fused by the Heat Roller heated by the Heater Lamp (H1), and
securely fixed by the pressure between the Heat Roller and Backup
Roller.
Paper Separator
Thermostat (TS1)
Thermistor (TH1)
Heater Lamp (H1)
Heat Roller
Paper
Backup Roller
Fusing Entrance Guide
11-2. Fusing Temperature Control Circuit
· The Thermistor (TH1) detects the surface temperature of the Heat Roller
and inputs that analog voltage into IC4-78. Corresponding to this data,
the Heater Lamp (H1) ON/OFF signal is output from IC4-55, causing
the Heater Lamp (H1) to turn ON or OFF to control the fusing
temperature.
· When the Heater Lamp (H1) is not turned OFF even if the Thermistor
(TH1) detects a high temperature malfunction (if the surface
temperature of the Heat Roller exceeds 230
°
C), the signal from IC4-79
changes from L to H to turn OFF the Heater Lamp (H1) forcibly.
1
2
1
2
CN2
2
1
TH1
1
2
CN2
H1
TS1
DC5V
78
IC4
3
2
1
Q103
GND
DC5V
IC3
79
55
CMPOUT
P01
CMPIN/AN8/P63
GND GND
H1: ON
H1: OFF L
H
H
L
L
L
1
2
3
CN7
4
5
1
2
3
4
5
CN1
6
7
6
7
+24VMAIN
GND(MG)
GND(DG)
GND(DG)
HEATER ON
+5VSUB
+5VMAIN
N.C.
HEAT_N
HEAT_L 3
Heater Lamp
Thermostat
Thermistor
Printer PWB (PWB-A)
Power Supply PWB
HEATER-RELAY OFF
8
8
Fig. 11
(At 600 dpi)
The printer is initialized upon power supply. The Heater Lamp then turns
on and the printer starts warming up. The temperature is controlled as
follows.
Mode 1: The temperature is controlled to maintain 125
°
C during standby
and 210
°
C during printing. If this mode continues for 300
seconds, the control will shift to mode 2.
Mode 2: The temperature of the Heat Roller falls gradually to about 190
°
C
from about 210
°
C. If this mode continues for 208 seconds, the
control will shift to mode 3.
Mode 3: The temperature is controlled to maintain 125
°
C during standby
and 190
°
C during printing. Unless an error occurs or the control
is opened, this mode is maintained.
Fig. 12
125
°
C
190
°
C
210
°
C
Temperature (
°
C)
Warming-up
Mode 1: 300sec Mode 2: 208sec Mode 3
Standby
Printing
(600 dpi)
155
°
C
160
°
C
Printing
(1200 dpi)
Thermistor detecting temperature
Temperature immediately after temperature control start
The state before Less than 50
°
C 50
°
C or more, 125
°
C or more,
discontinuation of less than 125
°
C
temperature control
Mode 1, warming-up Mode 1
Mode 2, 3 Mode 1 Mode 2 Mode 3
or Power OFF