15 February 2006 LASER EXPOSURE
6-45
Detailed
Descriptions
6.7 LASER EXPOSURE
6.7.1 OVERVIEW
There are four laser diodes. Four parallel beams write four lines at once, 24 lines
with one complete rotation of the polygon mirror, with the polygon motor rotating at
42,756 rpm.
Multiple beam scanning achieves:
• Longer life of the polygon motor (four-beam scanning requires fewer motor
rotations)
• Quieter operation because fewer polygon motor revolutions are required.
Up to 5 image density levels (0 ~ 4) are used for each pixel. To achieve this, this
machine controls the duration of the laser exposure using PWM (Pulse Width
Modulation).
(! Digital Processes> Printing> Laser Printing> Image Processing)
The strength of each beam is 10 mW/channel at a wavelength of 788 nm.
Specifications
Semi-conductor laser encased in an aluminum die-cast bracket.
Wavelength: 788 nm
Output: 10 mW/channel (13.3 mW/channel for B246 Series)
4-beam exposure
APC (Auto Power Control) provided
LD Unit
Gradation control with PWM
Light weight, aluminum die-cast housing
Main line scanning by polygon mirror
Fθ lens controls the beam position and focus in the main scan direction.
Line Scanning
Beam focus correction by WTL.
Polygon Motor 42,756 rpm
NOTE: 1) A new ceramic shaft increases the durability of the polygon motor.
2) This machine uses APC (Auto Power Control), so no adjustments are
required when the LD unit is replaced.
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