DOWNLOAD Sharp AR-651 (serv.man17) Service Manual ↓ Size: 647.22 KB | Pages: 21 in PDF or view online for FREE

Model
AR-651 (serv.man17)
Pages
21
Size
647.22 KB
Type
PDF
Document
Service Manual
Brand
Device
Copying Equipment / Fuser unit
File
ar-651-sm17.pdf
Date

Sharp AR-651 (serv.man17) Service Manual ▷ View online

AR-651/810  FUSER UNIT  14 - 1
14.  FUSER UNIT
14. 1.  General Description
The toner is fused on the paper separated from the photoconductive drum by applying heat and pressure to
it. The paper is then discharged through the paper exit section. The fuser unit consists of the IH coil, fuser
roller, pressure roller, separation fingers, cleaning web, cleaning rollers, thermistors, thermostat, exit rollers,
exit sensor, etc.
14. 2.  Operation
At the fuser unit, the toner is fused on the paper which has been separated and transported from the
photoconductive drum by applying heat and pressure to it.
The fuser roller is rotated by the driving of the fuser motor and has an IH coil inside, which does not rotate
itself. The fuser and pressure rollers are always pressured by a spring force.
After being fused, the paper is separated smoothly from the fuser roller by the separation fingers.
The thermistor detects the fuser roller temperature to control it, and when the temperature becomes
abnormally high, which is detected by the thermostat, the power supply to the IH coil is cut off.
Web pushing roller
Cleaning web
Web detection sensor
Web motor
Exit roller
Separation finger
Fuser unit exit sensor
Cleaning roller (metal)
Pressure roller
Cleaning roller (felt)
Fuser roller thermistor
Thermostat
IH coil
Pressure roller thermistor
[Sectional view]
Fuser roller
AR-651/810  FUSER UNIT  14 - 2
14. 3.  Functions
(1) IH coil (IH: Induction heating)
The IH coil is inside the fuser roller and applies the induction heat to the fuser roller. This IH coil is
divided into two parts, the center IH coil heating the center of the fuser roller and the side IH coil
heating both ends of the fuser roller. Those parts become ON/OFF separately to always keep the fuser
roller at a certain temperature without wasting excessive electric power.
(2) Fuser roller
The fuser roller is made of iron and induction-heated by the IH coil. It is pressed by the pressure roller,
which is mentioned below, and the toner is fused on the peper while the paper is passing through
between these two rollers with the toner image on the paper facing the fuser roller. So, the toner soaks
into the fibers of the paper by melting it with the heat of the fuser roller and improving the heat conductivity
by the pressure from the pressure roller.
The surface of the fuser roller is coated with plastic to prevent the toner adhering to the roller (the
phenomenon called “offset”) and help it separate from the fuser roller.
(3) Pressure roller
The pressure roller is made of rubber to make it easier to press the fuser roller and always pressed by
a spring force.
(4) Separation fingers
The separation fingers take off the paper that has stuck to the fuser and pressure rollers.
(5) Cleaning web
The cleaning web is attached in touch with the fuser roller by the web pushing roller to remove the toner
and paper dust that have stuck to the fuser roller during the fusing process. It is rolled up by the motor
so that its clean surface always touches the fuser roller, and also it contains silicon oil for coating the
surface of the fuser roller, which makes it easier to clean up the toner and paper dust on the fuser roller.
(6) Cleaning rollers
The cleaning rollers are attached in touch with the pressure roller to remove the toner and paper dust
that have stuck to the pressure roller during the fusing process. There are two kinds of rollers, a metal
roller and felt roller. The felt cleaning roller contains silicon oil for coating the surface of the pressure
roller, which makes it easier to clean up the toner and paper dust on the pressure roller.
(7) Exit roller
The exit roller of the fuser unit discharges the paper separated from the fuser and pressure rollers with
the separation fingers through the fuser unit.
(8) Fuser unit exit sensor
AR-651/810  FUSER UNIT  14 - 3
This sensor is for detecting that the trailing edge of the paper has reached the fuser unit exit sensor and
also for detecting of paper jams at the fuser unit exit section.
(9) Fuser roller center thermistor/Fuser roller side thermistor (rear)
This thermistor detects the temperature of the fuser roller to maintain it in a certain range, which is
higher than the lower limit causing the poor fusing and lower than the upper limit causing the high
temperature offset. When the temperature of the  fuser roller is lower than the preset temperature, it
turns ON the power supply to the IH coil, and when it is higher than the preset temperature, it cuts OFF
the supply. It also detects the slight different of the temperatures at the center and rear end of the fuser
roller to control ON/OFF of the center and side IH coil to keep the fuser roller at a certain temperature.
(10) Fuser roller side thermistor (front)
This thermistor cannot be used for the temperature control. It detects a temperature abnormality at the
side area of the fuser roller where paper does not pass through.
(11) Thermostats (center, front)
The center and front thermostats cut off the power supply to the IH coil when the  fuser roller becomes
abnormally hot as the result of a problem such as the thermistor malfunction. The thermostats of this
copier are used to prevent abnormal operations, and when they detect any abnormality, they must be
replaced altogether with the other damaged parts of the fuser unit.
AR-651/810  FUSER UNIT  14 - 4
NL
CPU
LGC
IH
5V SW
5V SW
14. 4.  Heater Control Circuit
14. 4. 1.  Configuration
[Block diagram of fuser unit and IH control circuit]
P
o
w
er code
Breaker
Side thermistor
     (front)
Center
thermistor
Thermostat
Coil
Noise
filter
Fuse
AC
input
Coil
output
IH power source/
drive circuit
Control circuit
including CPU
Photocoupler
AC line
DC line
P
o
w
er supply f
o
r
photocoupler
Electric power setting
Error signal
IH ON/OFF signal
Drum
thermistor
T
emper
ature
control circuit
Side thermistor
       (rear)
Fuser roller
Page of 21
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  • DOWNLOAD Sharp AR-651 (serv.man17) Service Manual ↓ Size: 647.22 KB | Pages: 21 in PDF or view online for FREE
  • Here you can View online or download the Service Manual for the Sharp AR-651 (serv.man17) in PDF for free, which will help you to disassemble, recover, fix and repair Sharp AR-651 (serv.man17) Copying Equipment. Information contained in Sharp AR-651 (serv.man17) Service Manual (repair manual) includes:
  • Disassembly, troubleshooting, maintenance, adjustment, installation and setup instructions.
  • Schematics, Circuit, Wiring and Block diagrams.
  • Printed wiring boards (PWB) and printed circuit boards (PCB).
  • Exploded View and Parts List.