Sharp AR-5132 Service Manual page 6

LSU internal structure
Convergence
lens for BD
Polygon
motor
Polygon
motor fan
drive PWB
lens
(Cylindrical lens)
Side view
Polygon motor
Collimator Cylindrical
L.D
lens lens
Sub scanning direction
f Θ lens 3
BD PWB
Mirror
f Θ lens 2
f Θ lens 1
Mirror for BD
Leser drive PWB
f Θ lens 3 Mirror
f Θ lens 1
f Θ lens 2
Cover glass
Drum
Lens
Functions of major parts
1
Collimator lens
Converges laser beams into parallel beams.
2
Cylindrical lens
Corrects laser beams in the sub scanning direction by shift of the
surface of the polygon mirror.
3
BD (Mirror, lens, PWB)
Detects the start timing of the laser scanning.
4
fθ lens
•
Converges laser beams on a spot on the OPC drum.
•
Equalizes the scanning speeds of laser beams at both ends
and at the center.
5
Polygon mirror, polygon motor
Reflects laser beams at constant rotation.
6
Semiconductor laser
Generates laser beams.
Drum
1 – 3
a ≠ b ≠ c
a b c
f Θ LENS
d = e = f
d e f