Epson EPL-5500, Service Manual, Page: 56 / 145

2.1.1.3 Laser Exposure
The laser beam, emitted from the optical unit, makes an invisible static image. The SOS (start of
scan) sensor, installed on the laser diode control board (PWB-D), unifies the laser emission timing
for each scan line.
2.1.1.4 Development
Toner is applied to the invisible static image on the PC drum and a toner image is created on the
surface. When the PC drum starts to rotate (when the main motor is activated), the PC drum
surface remains 0 V at the position between the rotating charge brush and sleeve roller. At this
time, a specified positive voltage is applied to the sleeve roller to prevent toner from being attracted
back onto the PC drum (reverse bias control).
1. Toner hopper: Contains toner.
2. Toner agitating screw: Stirs the toner in the hopper and sends the toner to the toner transport
roller.
3. Toner transport roller: Transports the toner to the sleeve roller.
4. Doctor blade: Spreads a thin, even coat of toner over the resin sleeve. The toner is negatively
charged by passing between this blade and resin sleeve.
5. Sleeve roller: Rotates the resin sleeve.
6. Resin sleeve: Carries the toner to the PC drum surface for development.
7. Bias seal: Collects the toner remaining on the resin sleeve.
8. PC drum: Is exposed to the laser to create an invisible image and rotates to carry the developed
image to the paper surface.
Charged Surface
Laser-Exposed Surface:
(Approx. -50 V)
PWB-D
SOS Sensor
Reflector Mirror
Laser Diode
M2
CN210
CN205
C169 MAIN-B
IC201
1
5
1
7
Figure 2-6. Laser Exposure
2
4
3
Vs terminal
VB terminal VBL terminal
VB (Developing Bias)
VBL (Toner Blade Bias)
Vs (Lower Seal Bias)
PWB-F
CN1F
CN204
C169 MAIN-B
IC201
1
8
1
8
Figure 2-7. Development
EPL-5500 Service Manual Operating Principles
Rev. B 2-5