Star Micronics LS-5 SERIES, Technical Manual

Page: 16 / 204

– 12 –
THEORY OF OPERATION
•
Descriptions of Printing Process
Process Contents
Charging The surface of the drum rotated by the BCR (bias charge roll) in the EPX toner cartridge
is negatively charged uniformly.
The ROS assembly converts image signals from the main logic board into optical signals
(laser beam), the laser beam scanning on the drum enabling exposure.
Scanning Exposure When an image is present, a laser is emitted. The laser beam is irradiated on the drum
surface, the negative charge of irradiated portions moves to the earth, thus enabling an
invisible electrostatic latent image to be formed on the drum surface.
The electrostatic latent image on the drum surface attracts toner on the magnetic roll surface
in the EPX toner cartridge, which is developed into a visible image on the drum surface.
Developing The toner is magnetic component. The magnet inside the magnetic roll causes the toner to
adhere to the roll, and the friction between the magnetic roll as it rotates and the CM
blade(Charge Metal Blade:the blade which charges the toner) converts the toner to a
negative charge, so that a thin layer of toner is formed on the surface of the magnetic roll.
The positive charge is impressed from the back of paper by the BTR (Bias Transfer Roll)
of the BTR assembly, thereby enabling toner on the drum surface to be transferred on the
paper.
Transfer
Impressing plus charge from the back of paper causes the paper itself to be electrically
charged plus to adhere to the drum.
Separation
The eliminator of the trans. chute assembly causes electric charge of the paper to flow to the
earth to weaken the adhesion to the drum of the paper, and the flexibility of the paper enables
the paper together with transferred toner to be separated from the drum.
Fusing
Toner on the paper is fused on it in the fuser assembly by means of heat of the heat roll with
the heater rod as a heat source and pressure of the pressure roll.
Cleaning
Part of toner not transferred on the paper during transfer remains on the drum. This residual
toner is scraped away by the cleaning blade in contact with the drum surface.
Figure 2-2 Printing Process (Drum’s Surface)
–V
0
–360V
–V
0
–360V
–V
0
–360V
Laser Beam
Electrostatic Latent
Image (Invisible Image) Toner Image
(Visible Image)
–270V
(Developing Bias)
Charging Scanning Exposure Developing
Voltage
Drum’s Surface