AL-1622 (serv.man9). Operational descriptions — Sharp Copying Equipment Service Manual (repair manual)

Model
AL-1622 (serv.man9)
Pages
8
Size
178.27 KB
Type
PDF
Document
Service Manual
Brand
Device
Copying Equipment / Operational descriptions
File
al-1622-sm9.pdf
Date

View Sharp AL-1622 (serv.man9) Service Manual online

AL-1611/AL-1622
OPERATIONAL DESCRIPTIONS
6 – 1
[ 6 ] OPERATIONAL DESCRIPTIONS
1. OUTLINE OF OPERATION
The outline of operation is described referring to the basic configuration.
(Basic configuration)
Outline of copy operation
A. Setting conditions: Operation panel
• Set copy conditions such as the copy quantity and the copy density
with the operation section, and press the START key. The informa-
tion on copy conditions is sent to the MCU.
B. Image scanning: Scanner section
•  When the START key is pressed, the scanner section starts scanning
C. Photo signal/Electric signal conversion: 
Scanner section
• The image is converted into electrical signals by the CCD circuit and
passed to the MCU.
D. Image process: MCU
under the revised conditions and sent to the LSU (laser unit) as print
data.
E. Electric signal/Photo signal 
(laser beam) conversion: LSU
• The LSU emits laser beams according to the print data. (Electrical
signals are converted into photo signals.)
•  The laser beams are radiated through the polygon mirror and various
lenses to the OPC drum.
F. Printing: Process section
•  Electrostatic latent images are formed on the OPC drum according to
the laser beams, and the latent images are developed to be visible
images (toner images).
•  Meanwhile the paper is fed to the image transfer section in synchroni-
zation with the image lead edge.
•  The toner image is transferred on the paper.
G. Fusing: Fusing section
•  Heat and a pressure are applied to the toner image on the copy paper
to fuse the image on the paper. 
2. SCANNER SECTION
A. Scan process 
tially. When the line is finished, the next line is scanned, and this proce-
dure is repeated. The figure below shows the case where an image
which is scanned is shown with solid lines.
The direction of this line is called main scanning direction, and the scan-
ning direction sub scanning direction. In the figure above, one line is
divided into 5 sections. Actually, however, one line is divided into thou-
sands of sections. For scanning, the light receiving element called CCD
is used.
The basic resolution indicates the scanner capacity. The basic resolu-
The basic resolution of this machine is 400dpi.
In the sub scanning direction, at the same time, the motor that drives
the optical system is controlled to scan the image at the basic resolu-
tion.
Operation
section
Scanner section
CCD 
MCU (Main control/image process section)
Laser beam
Paper exit
Fusing 
section
Paper t
ransport 
section
Manual paper
feed section
Cassette paper
feed section
Printer section
LSU (Laser unit)
Laser diode, Polygon mirror lens
Process section
1
2
3
4
5
5
4
3
2
1
Sub scanning direction
Sensor scanning area
Main 
scanning 
direction
To MCU PWB
AL-1611/AL-1622
OPERATIONAL DESCRIPTIONS
6 – 2
B. Basic structure of scanner section
The light from the light source (Xenon lamp) is reflected by a document and passed through three mirrors and reduction lenses to the CCD element
(image sensor) where images are formed. This system is known as the reduction image sensor system. Photo energy on the CCD element is con-
verted into electrical signals (analog signals). (Photo-electric conversion). The output signals (analog signals) are converted into digital signals (A/D
conversion) and passed to the MCU (main control/image process section). The resolution at that time is 400dpi. The mirror unit in the scanner section
is driven by the mirror motor. The MHPS is provided to detect the home position of the copy lamp unit.
3. PROCESS SECTION
A. Basic structure
1
Copy lamp (Xenon lamp)
Generate photo energy to scan documents.
2
Reflector (Converging plate)
Collects light emitted from the copy lamp and radiate the document.
3
No. 1 mirror
Refracts the reflection light from the document to No. 2 mirror.
4
No. 2 mirror
Refracts the reflection light from No. 1 mirror.
5
No. 3 mirror
Refracts the reflection light from No. 2 mirror.
6
Lens
Converges reflected light from the document to form images on the CCD element.
7
No. 2/3 mirror unit
Includes No. 2/3 mirror. Driven in synchronization with the copy lamp unit.
8
Copy lamp unit
Includes the copy lamp, the reflector, and No. 1 mirror. Driven in synchronization with No. 2/3
mirror unit by the mirror motor.
9
CCD PWB
Reflected light (image) formed on the CCD is converted into electrical signals (analog signals)
then into digital signals and sent to the MCU.
10
Mirror motor
Drives the copy lamp unit and No. 2/3 mirror unit according to the scanning speed.
11
MHPS (Mirror home position sensor)
Detects the home position of No. 2/3 mirror unit.
12
Reference white plate
Reference white sheet for scanning documents. The reference line of magnification ratio
adjustment during SIM is also drawn.
13
OC glass
Glass table to put a document on it.
1
Main charger unit
Charges the OPC drum.
2
Cleaning blade
Collects waste toner on the OPC drum.
3
OPC drum
Images are formed by laser beams electri-
cally, and toner is attached to the image.
4
Transfer unit
Toner on the OPC drum is transferred to the
print paper by the potential difference.
5
Resist roller
Makes synchronization between the paper
and the print image.
6
MG roller
Magnetic brush is formed by developer to
put toner on the OPC drum.
7
(Laser beam)
Forms images on the OPC drum.
AL-1611/AL-1622
OPERATIONAL DESCRIPTIONS
6 – 3
Operation cycle
B. Outline of print process
The printer section of this machine employs the laser print system
where print images are formed by the laser beams on the OPC drum.
A high voltage (corona) is applied from the main charger to the OPC
drum to charge the OPC drum. 
Laser beams are radiated to the charged OPC drum to form electrical
images on the OPC drum. (Exposure)
(At that time, the print image on the OPC drum cannot be seen: latent
electrostatic image)
By the potential difference between the unexposed area and the latent
electrostatic images, toner ia attracted only to the images. (Developing)
(At that time, the print image formed by toner on the OPC drum can be
seen. Visible images)
The toner image on the OPC drum is transferred on the print paper by
the transfer corona (voltage). 
After that, the print paper with the toner image on it is subject to heat
and pressure in the fusing section to fuse the image on the paper.
This machine employs the following organic photoconductor (OPC)
drum.
C. Actual print process
(1) Charging
A high voltage is applied to the main charger, and negative charges are
discharged to the OPC drum. A screen grid is provided between the
main charger and the OPC drum, and negative charges are uniformly
charged on the OPC drum surface.
Positive charges are attracted by the negative electrode on the OPC
drum surface and excited in the aluminum layer in the OPC drum.
Paper exit roller
Paper exit
Heat roller
Fusing
Cleaning blade
Waste toner box
Separation
Cleaning
Separation charger
High voltage power
High voltage power
Main charger
Charging
Transfer
Transfer
Transfer charger
High voltage power
Laser scanning unit
Laser beam
Exposure
Developing
Synchronization 
with drum
Resist roller
High voltage
power
Developing unit
Toner hopper
Developer
Toner
Cassette paper 
feed
Manual paper 
feed
(20microns thick)
Aluminium drum
Pigment layer (0.2
to 0.3 microns thick)
An OPC drum is used for the photoconductor.
(Structure of the OPC drum layers)
OPC layer
DC5.5KV
(-525V/-400V)
AL-1611/AL-1622
OPERATIONAL DESCRIPTIONS
6 – 4
(2) Exposure 
A Laser beam is generated from the semiconductor laser and controlled
by the print pattern signal. The laser writes onto the OPC drum surface
through the polygon mirrors and lens. The resistance of the OPC layer
decreases for an area exposed by the laser beam (corresponding to the
print pattern signal). The beam neutralizes the negative charge. An
electrostatic latent image is formed on the drum surface.
(3) Developing (DC bias)
A bias potential is applied to the MG roller in the two component mag-
netic brush developing method, and the toner is charged negative
through friction with the carrier. Non-image area of the drum surface
charged with negative potential repel the toner, whereas the laser
exposed portions where no negative charges exist, attract the toner. As
a result, a visible image appears on the drum surface.
Toner is attracted over the shadowed area because of the developing
bias.
(4) Transfer
The visible image on the drum surface is transferred onto the print
paper by applying a positive charge from the transfer corona to the
backside of the print paper.
(5) Separation
Since the print paper is charged positively by the transfer corona, it is
discharged by the separation corona. The separation corona is con-
nected to ground.
(6) Cleaning
Toner remaining on the drum is removed and collected by the cleaning
blade. It is transported to the waste toner collecting section in the clean-
ing unit by the waste toner transport roller.
OPC layer
Pigment
layer
Aluminum
OPC layer
Pigment
layer
Aluminum
layer
Drum surface charge
sfter the exposure
Non-image area
Image area
Semiconductor laser
Exposure
(semiconductor laser)
layer
S
N
N
MG roller
 
DC
-400v
-8V
: Carrier (Magnetized particle)
: Toner (Charge negative by friction)
(N) (S) : Pemanent magnet
            (provided in three locations)
-600
0
Toner attract
potential
D
ru
m
 s
u
rfac
e p
o
te
nt
ia
l
Non-image area
Developing bias
Image area
Residual potential (-50 to -100V)
Charge
Exposure
Developing
Transfer
Discharge
Charge
Time
-400
Page of 8

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