Sharp AL-2020 (serv.man2) Service Manual ▷ View online
AL-2040 OPERATIONAL DESCRIPTIONS 7 - 3
3. Laser unit
The image data sent from the MCU (image process circuit) is sent
to the LSU (laser unit), where it is converted into laser beams.
to the LSU (laser unit), where it is converted into laser beams.
A. Basic structure
The LSU unit is the writing section of the digital optical system.
The semiconductor laser is used as the light source, and images
are formed on the OPC drum by the polygon mirror and f
are formed on the OPC drum by the polygon mirror and f
θ lens,
etc.
The laser beams are passed through the collimator lens, the cylin-
drical lens, the polygon mirror, the f
drical lens, the polygon mirror, the f
θ lens, and the mirror to form
images on the OPC drum in the main scanning direction. The laser
emitting PWB is provided with the APC (auto power control) in
order to eliminate fluctuations in the laser power. The BD PWB
works for measurement of the laser writing start point.
emitting PWB is provided with the APC (auto power control) in
order to eliminate fluctuations in the laser power. The BD PWB
works for measurement of the laser writing start point.
Makes the laser scanning speeds at both ends of the drum same
as each other.
as each other.
B. Laser beam path
C. Composition
Effective scanning width: 216mm (max.)
Resolution: 600dpi
Beam diameter: 75um in the main scanning direction, 80um in the
sub scanning direction
sub scanning direction
Image surface power: 0.18 ± 0.01mW (Laser wavelength 770 -
795nm)
795nm)
Polygon motor section: Brushless motor 20.787rpm
No. of mirror surfaces: 5 surfaces
No. of mirror surfaces: 5 surfaces
4. Fuser section
No
Component
Function
1 Semiconductor laser
Generates laser beams.
2 Collimator lens
Converges laser beams in parallel.
3 Cylinder lens
Takes the focus.
4 Polygon mirror,
polygon motor
Reflects laser beams at a constant
rpm.
rpm.
5 BD (Lens, PWB)
Detects start timing of laser
scanning.
scanning.
6 f
θ lens
Converges laser beams at a spot on
the drum.
the drum.
Makes the laser scanning speeds at
both ends of the drum same as each
other. (Refer to the figure below.)
both ends of the drum same as each
other. (Refer to the figure below.)
2
3
3
6
4
1
5
6
a
≠ b ≠ c
a
b
c
d = e = f
d
e
f
f
θ
LENS
AL-2040 OPERATIONAL DESCRIPTIONS 7 - 4
A. General description
General block diagram (cross section)
Top view
(1) Heat roller
A Teflon roller is used for the heat roller and a silicone rubber roller
is used for the lower heat roller for better toner fusing performance
and paper separation.
is used for the lower heat roller for better toner fusing performance
and paper separation.
(2) Separator pawl
Three separator pawls are used on the upper heat roller. The sep-
arator pawls are Teflon coated to reduce friction with the roller and
prevent a smear on the paper caused by the separator pawl.
arator pawls are Teflon coated to reduce friction with the roller and
prevent a smear on the paper caused by the separator pawl.
(3) Thermal control
1) The heater lamp, thermistor, main PWB, DC power supply
PWB, and triac within the power supply unit are used to control
the temperature in the fuser unit.
To prevent against abnormally high temperature in the fuser
unit, a thermal breaker and thermal fuse are used for safety
purposes.
the temperature in the fuser unit.
To prevent against abnormally high temperature in the fuser
unit, a thermal breaker and thermal fuse are used for safety
purposes.
2) The surface temperature of the upper heat roller is set to 160 -
200°C. The surface temperature during the power save mode
is set to 100°C.
is set to 100°C.
3) The self-check function comes active when one of the follow-
ing malfunctions occurs, and an "H" is displayed on the multi-
copy window.
copy window.
a. When the heat roller surface temperature rises above 240°C.
b. When the heat roller surface temperature drops below 100°C
during the copy cycle.
c. Open thermistor
d. Open thermal fuse
e. When the heat roller temperature does not reach 190°C within
27 second after supplying the power.
(4) Fusing resistor
This model is provided with a fusing resistor in the fusing section
to improve transfer efficiency.
to improve transfer efficiency.
Since the upper heat roller is conductive, when using copy paper
that contains moisture and the distance between the transfer unit
and the fusing unit is short, the transfer current may find a path to
ground via the copy paper, the upper heat roller and the discharg-
ing brush.
that contains moisture and the distance between the transfer unit
and the fusing unit is short, the transfer current may find a path to
ground via the copy paper, the upper heat roller and the discharg-
ing brush.
5. Paper feed section and paper
transport section
A. Paper transport path and general operations
Paper feed is made in two ways; the tray paper feed and the man-
ual paper feed. The tray is of universal-type, and has the capacity
of 250 sheets.
ual paper feed. The tray is of universal-type, and has the capacity
of 250 sheets.
The front loading system allows you to install or remove the tray
from the front cabinet.
from the front cabinet.
The general descriptions on the tray paper feed and the manual
paper feed operation are given below.
paper feed operation are given below.
Separator pawl
Separator pawl
PPD2
Thermal fuse
Thermistor
Heat roller
Paper guide
Pressure roller
Heat roller
Thermistor
Thermal fuse
Heater lamp
Separator pawl
Safety device
(thermal breaker, thermal
fuse)
(thermal breaker, thermal
fuse)
Triac (in the
power supply unit)
power supply unit)
Heated by the heater
lamp. (950W)
The surface temperature
of the upper heat roller is
sensed by the thermistor.
of the upper heat roller is
sensed by the thermistor.
Level of the thermistor is
controlled by the main PWB.
controlled by the main PWB.
With the signal from the
main PWB, the triac is
controlled on and off.
(power supply PWB)
main PWB, the triac is
controlled on and off.
(power supply PWB)
1
Scanner unit
8
Drum
2
Copy lamp
9
Transfer unit
3
LSU (Laser unit)
10
Pickup roller
4
Paper exit roller
11
Manual paper feed tray
5
Main charger
12
Manual paper feed roller
6
Heat roller
13
PS roller unit
7
Pressure roller
14
Paper feed roller
1
5
4
3
7
6
8
9
11
12
13
14
10
2
AL-2040 OPERATIONAL DESCRIPTIONS 7 - 5
(1) Cassette paper feed operation
1) The figure below shows the positions of the pick-up roller, the
paper feed clutch sleeve, and the paper feed latch in the initial
state without pressing the COPY button after lighting the ready
lamp.
The paper feed latch is in contact with the projection of the
clutch sleeve.
state without pressing the COPY button after lighting the ready
lamp.
The paper feed latch is in contact with the projection of the
clutch sleeve.
2) When the COPY button is pressed, the main drive motor starts
rotating to drive each drive gear.
The pick-up drive gear also is driven at that time. Since, how-
ever, the paper feed latch is in contact with the projection of
the clutch sleeve, rotation of the drive gear is not transmitted to
the pick-up roller, which does not rotate therefore.
The pick-up drive gear also is driven at that time. Since, how-
ever, the paper feed latch is in contact with the projection of
the clutch sleeve, rotation of the drive gear is not transmitted to
the pick-up roller, which does not rotate therefore.
3) After about 0.1 sec from when the main motor start rotating,
the tray paper feed solenoid (PFS) turns on for a moment.
This disengages the paper feed latch from the projection of the
clutch sleeve, transmitting rotation of the pick-up drive gear to
the paper feed roller shaft, rotating the pick-up roller to feed
the paper.
This disengages the paper feed latch from the projection of the
clutch sleeve, transmitting rotation of the pick-up drive gear to
the paper feed roller shaft, rotating the pick-up roller to feed
the paper.
4) After more than half rotation of the pick-up roller, the paper
feed latch is brought in contact with a notch on the clutch
sleeve, stopping rotation of the pick-up roller.
sleeve, stopping rotation of the pick-up roller.
5) At this time, the paper is fed passed the paper entry detection
switch (PPD1), and detected by it. After about 0.15 sec from
detection of paper by PPD1, the tray paper feed solenoid
(PFS) turns on so that the clutch sleeve projection comes into
contact with the paper feed latch to stop the pick-up roller.
Then the pick-up roller rotates for about 0.15 sec so that the
lead edge of the paper is evenly pressed on the resist roller,
preventing against skew feeding.
detection of paper by PPD1, the tray paper feed solenoid
(PFS) turns on so that the clutch sleeve projection comes into
contact with the paper feed latch to stop the pick-up roller.
Then the pick-up roller rotates for about 0.15 sec so that the
lead edge of the paper is evenly pressed on the resist roller,
preventing against skew feeding.
6) To release the resist roller, the tray paper feed solenoid and
the resist solenoid are turned on by the paper start signal to
disengage the resist start latch from the clutch sleeve, trans-
mitting rotation of the resist drive gear to the resist roller shaft.
Thus the paper is transported by the resist roller.
disengage the resist start latch from the clutch sleeve, trans-
mitting rotation of the resist drive gear to the resist roller shaft.
Thus the paper is transported by the resist roller.
7) After the resist roller starts rotating, the paper is passed
through the pre-transfer guide to the transfer section. Images
are transferred on the paper, which is separated from the OPC
drum by the drum curve and the separation section.
are transferred on the paper, which is separated from the OPC
drum by the drum curve and the separation section.
8) The paper separated from the drum is passed through the fus-
ing paper guide, the heat roller (fusing section), POD (paper
out detector) to the copy tray.
out detector) to the copy tray.
OFF
PFS
OFF
RRS
OFF
PFS
OFF
RRS
ON
PFS
OFF
RRS
OFF
PFS
ON
RRS
AL-2040 OPERATIONAL DESCRIPTIONS 7 - 6
(2) Manual multi paper feed operation
1) Before paper feed operation, the manual paper feed solenoid
(MPFS) is turned OFF as shown in the figure below.
2) When the PRINT button is pressed, the manual paper feed
solenoid (MPFS) turns on to disengage the manual paper feed
latch.
A from the manual paper feed clutch sleeve A, rotating the
manual paper feed roller and the manual take-up roller. At the
same time, the manual paper feed stopper opens and the
manual take-up roller is pressed to the surface of the paper to
start paper feeding.
latch.
A from the manual paper feed clutch sleeve A, rotating the
manual paper feed roller and the manual take-up roller. At the
same time, the manual paper feed stopper opens and the
manual take-up roller is pressed to the surface of the paper to
start paper feeding.
3) When pawl C of the manual paper feed clutch sleeve is
engaged with the manual feed latch, the manual feed stopper
falls and the manual take-up roller rises. At that time, the man-
ual paper feed roller is rotating.
falls and the manual take-up roller rises. At that time, the man-
ual paper feed roller is rotating.
4) The lead edge of the transported paper is pressed on the
resist roller by the transport roller. Then the paper is stopped
temporarily to allow synchronization with the lead edge of the
image on the OPC drum.
From this point, the operation is the same as the paper feed
operation from the tray. (Refer to 7-5 - 8.)
temporarily to allow synchronization with the lead edge of the
image on the OPC drum.
From this point, the operation is the same as the paper feed
operation from the tray. (Refer to 7-5 - 8.)
5) The solenoid turns off to close the gate and return to the initial
state.
OF
MPFS
F
C
A
ON
MPFS
A
C
ON
MPFS
A
C
OF
MPFS
F
A
C
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