Ros; Main Function - Dell 3010CN Service Manual

3.1 ROS

3.1.1 Main function

ROS ASSY
ROS ASSY (Raster Output Scanner Assemble) is the exposure device that outputs laser beam
to form electrostatic latent image on the surface of drum. (hereinafter ROS ASSY is described
as ROS.)
ROS consists of the main parts shown below.
PWBA LD
Lens COL
Lens CYL
• PWBA LD (Laser Diode) converts image data of electric signal inputted into flashing of laser
beam. PWBA LD always monitors the power of laser beam and controls it at an appropriate
level so that the laser beam remains stable at forming electrostatic latent image. This is
called "APC (Auto Power Control)".
• Scanner Assy consists of Scanner Motor that rotates at regular speed and polygon mirror that
is attached to motor rotation shaft.
Laser beam output from PWBA LD irradiates polygon mirror.
Polygon mirror has 6 sides of reflecting mirrors, and reflecting angle of laser beam is changed
by rotation of Scanner Motor. According to the change in this reflecting angle, laser beam can
scan to drum shaft direction. 1 line is scanned on one reflecting mirror side.
• Laser beam reflected from polygon mirror reaches the surface of dram through the lens,
mirror and window. The lens corrects aberration, the mirror secures the light path and the
window prevents entry of foreign substances inside the ROS.
• SOS Sensor on PWBA SOS (Start of scan) converts the electric signal as a scanning start
standard when laser beam enters and sends the signal to PWBA MCU.
Signal of SOS Sensor is used to match timing to start scanning by laser beam and timing of
writing image.
Mirror SOS
Scanner Assy
Polygon Mirror
Drum
Lens L1
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Chapter 6 Principle s of O peration
Window
Mirror
SOS Sensor
PWBA SOS
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