Service manual
FO-4700U
FO-47UC
3 – 5
8. LASER EXPOSURE
Laser exposure is the process of creating an invisible static image on
the PC Drum by the laser beam emitted from the Print Head Unit.
In the sub-scanning direction (vertical direction)
When the printer receives the PRINT signal, the Polygon Motor and the
Printer Motor rotate and the paper is fed into the printer.
The printing in the sub-scanning direction is started when the Printer
PWB (PWB-A) sends the VIDEO signal to the Print Head a certain time
after the leading edge of the paper activates the Paper Sensor (TOD
signal).
The print starting position of the 2nd line is decided by delaying the
VIDEO signal sending timing.
In the scanning direction (horizontal direction)
The SOS Sensor is installed on the Laser Diode Control PWB (PWB-
D) to unify the laser emission timing for each scan line.
Charged Surface
Reflector Mirror
PWB-D
Laser Diode
M2
CN9
CN5
1
7
1
5
SOS Sensor
PWB-A
Laser exposed surface:
approx. -50V
Fig. 7
9. DEVELOPMENT
9-1. Overview
Toner is applied to the invisible static image on the PC Drum and a toner
image is created on the surface.
No. Part Name Function
1 Toner Hopper Contains toner.
2 Toner Agitating Screw Agitates the toner in the Toner Hopper and sends the toner to the Toner Transport Roller.
3 Toner Transport Roller Transports the toner to the Sleeve Roller.
4 Sleeve Roller Turns the Resin Sleeve.
5 Resin Sleeve Carries the toner to the PC Drum surface for development.
6 PC Drum Exposed to laser to create an invisible image and rotates to carry the developed image to the paper surface.
7 Doctor Blade Spreads a thin, even coat of toner over the Resin Sleeve. The toner is negatively charged when passing
between this Blade and the Resin Sleeve.
8 Bias Seal Collects the toner remaining on the Resin Sleeve and neutralizes charge.
1
6
2
Fig. 8
Toner Cartridge
1
2
3
4
5
6
7
8
V
SS
: DC-300V
V
B
: DC-300V
V
BL
: DC-550V
Lower Seal Bias terminal (V
SS
)
Developing Bias terminal (V
B
)
Toner Blade Bias terminal (V
BL
)