Specifications

AL-1551 OPERATIONAL DESCRIPTIONS 7-3
3. Laser unit
The image data sent from the MCU (image process circuit) is sent to the
LSU (laser unit), where it is converted into laser beams.
A. Basic structure
The LSU unit is the writing section of the digital optical system.
The semiconductor laser is used as the light source, and images are
formed on the OPC drum by the polygon mirror and fθ lens, etc.
The laser beams are passed through the collimator lens, the cylindrical
lens, the polygon mirror, the fθ lens, and the mirror to form images on the
OPC drum in the main scanning direction. The laser emitting PWB is
provided with the APC (auto power control) in order to eliminate
fluctuations in the laser power. The BF PWB works for measurement of
the laser writing start point.
Makes the laser scanning speeds at both ends of the drum same as
each other.
B. Laser beam path
C. Composition
Effective scanning width:216mm (max.)
Resolution:600dpi
Beam diameter: 75um in the main scanning direction, 80um in the sub
scanning direction
Image surface power:0.20 ±0.03mW (Laser wavelength 780 - 795nm)
Polygon motor section:Brushless motor 20.787rpm
No. of mirror surfaces:6 surfaces
4. Fuser section
No Component Function
(1) Semiconductor laser Generates laser beams.
(2) Collimator lens Converges laser beams in parallel.
(3) Polygon mirror,
polygon motor
Reflects laser beams at a constant rpm.
(4) BD (Mirror, lens, PWB) Detects start timing of laser scanning.
(5) fθ lens Converges laser beams at a spot on the
drum.
Makes the laser scanning speeds at both
ends of the drum same as each other.
(Refer to the figure below.)
(1)(2)
(3)
(4)
(5)
: Laser beam
path for BF PWB
a ≠ b ≠ c
ab c
d = e = f
def
fθ LENS