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III. LASER/SCANNER SYSTEM
A. Outline
Figure 2-3-1
The DC controller PCB receives the VIDEO signals (/VDO, VDO) from the video controller PCB
and sends then to the laser driver in the laser/scanner unit.
The laser driver turns the laser diode ON and OFF according to the video signal (/VDO, VDO)
and generates the modulated laser beam only when the VIDEO ENABLE signal (/LENBL) from
the DC controller is “L.”
The modulated laser beam is aligned by a collimator lens and a cylindrical lens into a paral-
lel beam which strikes the scanning mirror that is rotating at a specified speed.
The beam reflected from the scanning mirror is brought to a point of focus on the photosen-
sitive drum with the focusing lens and the mirror located in front of the scanning mirror.
As the scanning mirror rotates at a specified speed, the beam is scanned across the drum at
a specified speed.
The drum also rotates at a specified speed and the laser beam successively scans across its
surface. Thus the laser beam builds up an image on the drum surface.
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CHAPTER 2
/VSYNC
/VDO VDO
/BDIVDO
/SCNRDY/LENBL DRVES/LON/VDO
/BD
/SCND
External device
Video controller PCB
DC controller
Photosensitive drum
BD mirror
Cylindrical lens
Focusing lens
Scanning mirror
Scanner motor
Laser driver
Mirror
BD PCB