Sharp AM-300 (serv.man7) Service Manual ▷ View online
AM-300DE
3 – 9
7.11. Switching operation (3) from the fixed scan mode to the sheet scan mode
Rotation of the system gear releases the pin A on the planet gear A
mounting arm from the cam groove A. The planet gear A moves to the
intermediate position between the scan unit drive side gear and the
sheet scan drive side gear. At this time, the belt stops moving, and the
scan unit stops accordingly just before the sheet scan position.
mounting arm from the cam groove A. The planet gear A moves to the
intermediate position between the scan unit drive side gear and the
sheet scan drive side gear. At this time, the belt stops moving, and the
scan unit stops accordingly just before the sheet scan position.
7.12. Switching operation (4) from the fixed scan mode to the sheet scan mode
Rotation of the system gear releases the pin B on the planet gear B
mounting arm from the cam groove B, and the planet gear B is disen-
gaged from the system gear. After the disengagement, the system
gear is kept rotating in clockwise direction by the system gear biasing
spring. The scan unit locking lever is moved by the system gear, and it
stops after pushing the scan unit to the locking rib. Keep rotating the
motor in the counterclockwise direction for the sheet feeding opera-
tion.
mounting arm from the cam groove B, and the planet gear B is disen-
gaged from the system gear. After the disengagement, the system
gear is kept rotating in clockwise direction by the system gear biasing
spring. The scan unit locking lever is moved by the system gear, and it
stops after pushing the scan unit to the locking rib. Keep rotating the
motor in the counterclockwise direction for the sheet feeding opera-
tion.
Counterclockwise rotation:
switching operation
switching operation
Lever
Scan unit
Cam groove A
Pin A
Motor gear
(drive source)
System gear biasing spring
Planet gear B
Planet gear A
Scan unit locking lever
Sheet scan drive side gear train
Scan unit drive side gear train
System gear
Pin
(Scanner unit)
Locking rib
Counterclockwise rotation: Sheets
are fed to the sheet scan section.
are fed to the sheet scan section.
System gear biasing spring
Scan unit drive side gear train
Sheet scan drive side gear train
Scan unit locking lever
System gear
Planet gear A
Planet gear B
(drive source)
Motor gear
AM-300DE
3 – 10
8. Print process
8.1. Image forming process
Normal paper is used as print paper. A laser beam is used to expose
on the OPC surface to form latent electrostatic images, which are
developed into visible images (toner images) and are transferred on
paper. The basic operation is composed of the five processes: charg-
ing, exposure, development, transfer, and cleaning.
on the OPC surface to form latent electrostatic images, which are
developed into visible images (toner images) and are transferred on
paper. The basic operation is composed of the five processes: charg-
ing, exposure, development, transfer, and cleaning.
8.2. System diagram (1)
8.3. System diagram (2)
Fig. 7
Main
charger
brush
charger
brush
Separation
electrode
electrode
Transfer
charge
roller
charge
roller
Developing roller
Supply roller
Photoconductor
drum (OPC)
drum (OPC)
Laser Scanning Unit
Laser
beam
beam
DC: +3600V (D6 Cathode)
DC: -950V
AC: -570V <--> -1330V
DC: -500V
DC: +400V
DC: -280V
Paper
Toner
MC
TC
SV
DV
DC: -220V
Heat roller
Pressure roller
Heater lamp
FU-EARTH
Print
print
Cleaning
cleaning
Paper
100MOHM
100V
4.7MOH M 4.7MOHM
Transfer Charger
Roller Voltage
Roller Voltage
Development
Roller
Voltage
Roller
Voltage
Main Charger
brush Voltage
brush Voltage
High Voltage Power Supply Unit
Supply
Roller
Voltage
Roller
Voltage
CONTROL PWB
16bit CPU
IC21
IC21
57
56
TCON
MCON
PWMSIN
Constant
voltage
control
circuit
voltage
control
circuit
PWM
control
circuit
control
circuit
Logic
circuit
circuit
Oscillation
circuit
circuit
B51
Transformer
Transformer
High Voltage PWB Unit
Constant
voltage
control
circuit
voltage
control
circuit
Oscillation
circuit
circuit
Feedback circuit
Feedback circuit
B1
Transformer
Transformer
HV(+)
Rectifier
circuit
Rectifier
circuit
HV(-)
Rectifier
circuit
Rectifier
circuit
HV(-)
Rectifier
circuit
Rectifier
circuit
Constant
voltage(+)
circuit
voltage(+)
circuit
Constant
voltage(-)
circuit
voltage(-)
circuit
Short
circuit
circuit
Short
protection
circuit
protection
circuit
SV
DV
MC
TC
110M
Ω
250M
Ω
FU-EARTH
LASER MFP
Transfer Roller
Supply Roller
Developing Roller
Charger Roller
Heat Roller
Pressure Roller
Doctor
OPC DRUM
Separation electrode
Fig. 8
AM-300DE
3 – 11
8.4. Image forming process diagram
Main charger
brush
Scanning
mirror
Mirror
Lens
Laser diode
Toner
Paper exit
Fusing
Heater lamp
Separation
electrode
Separation
Transfer
Transfer roller
High voltage circuit
Paper feed roller
Paper tray
Paper
High voltage
circuit
Cleaning, Charge
Exposure
Development
cleaning
Developing
roller
High voltage
circuit
Heat roller
Pressure roller
Fig. 9
AM-300DE
3 – 12
8.5. Functions and operations of major parts
8.5.1 OPC drum unit
The OPC drum is charged and latent electrostatic images are formed
on it and developed into visible toner images.
on it and developed into visible toner images.
a. OPC drum
Latent electrostatic images are formed and developed into toner
images on the OPC drum.
images on the OPC drum.
Organic Photo Conductor is used. The OPC surface is charged nega-
tively by the main charger brush.
tively by the main charger brush.
When the OPC is exposed to laser beam, the electric resistance of the
exposed section falls and electric charge is generated in the OPC. As
a result, electric charge on the OPC surface is removed. This principle
is used to form latent electrostatic images.
exposed section falls and electric charge is generated in the OPC. As
a result, electric charge on the OPC surface is removed. This principle
is used to form latent electrostatic images.
b. Main charger brush
The main charger brush charges the OPC drum surface. It is com-
posed of brush fiber, and is in the shape of a roller. A high voltage of
AC 760V (P-P) and DC-950V are applied to charge the brush.
posed of brush fiber, and is in the shape of a roller. A high voltage of
AC 760V (P-P) and DC-950V are applied to charge the brush.
The main charger brush is in contact with the OPC drum. BY applying
electric charge to the OPC drum, the OPC drum is charged to about
DC-900V.
electric charge to the OPC drum, the OPC drum is charged to about
DC-900V.
8.5.2 Developing unit
Latent electrostatic images formed by laser beam on the OPC drum
are developed to visible images by the developing unit. Toner is filled
in the developing unit.
are developed to visible images by the developing unit. Toner is filled
in the developing unit.
a. Developing roller
The developing roller is made of urethane and has a high electric
resistance. It is flexible and is in close contact with the OPC drum.
Toner on the developing roller is attached to latent electrostatic images
on the OPC drum to form visible images on the OPC drum.
resistance. It is flexible and is in close contact with the OPC drum.
Toner on the developing roller is attached to latent electrostatic images
on the OPC drum to form visible images on the OPC drum.
A voltage of DC-220V is applied the developing roller.
b. Doctor
The doctor is in close contact with the developing roller. It adjusts toner
quantity on the developer roller surface.
quantity on the developer roller surface.
The doctor is made of conductive material.
c. Toner supply roller
Toner is supplied to the developing roller by the sponge roller which is
connected to the developing roller.
connected to the developing roller.
d. Toner stirring plate
This plate stirs toner in the developing unit to transport it to the devel-
oping roller smoothly.
oping roller smoothly.
8.5.3 Transfer charger roller
The transfer charger roller is made of urethane and has a high electric
resistance. It is flexible and is in close contact with the OPC drum.
resistance. It is flexible and is in close contact with the OPC drum.
A high voltage of AC 760V (P-P) and DC +3600V are applied to
charge.
charge.
It positively charges paper transported from the paper feed section,
which transfers negatively charged toner on the OPC drum onto the
paper.
which transfers negatively charged toner on the OPC drum onto the
paper.
8.5.4 Separation electrode
This electrode is connected to the drum ground. It discharges paper
which was positively charged in the transfer section to reduce the
potential difference with the OPC drum to reduce static electricity
between the paper and the OPC drum, thus facilitating separation of
paper.
which was positively charged in the transfer section to reduce the
potential difference with the OPC drum to reduce static electricity
between the paper and the OPC drum, thus facilitating separation of
paper.
Fig. 10
1
Developing roller
6
Separation electrode
2
Doctor
7
OPC drum
3
Toner stirring plate
8
Discharge plate
4
Toner supply roller
9
Main charger brush
5
Transfer roller
Fig. 11
2
4
1
7
5
6
3
Optical unit(LSU)
Paper
Toner
9
8
OPC layer
CTL (Charge transfer layer)
Aluminum layer
CGL (Charge generation layer)
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