Toshiba 4580, Service Manual

Page: 119 / 379

Mar. 1999 © TOSHIBA TEC 8 - 3 6570/5570 PRINTING
8.2 Structure
(1) Laser Unit
The laser unit comprises a laser diode, laser drive board, finite lens and aperture.
1
Laser diode and laser drive board
The laser diode controls emission of laser beams based on the laser control (ON/OFF) signals
from the laser drive board.
2
Finite lens
The finite lens focus the laser beam on the surface of the photosensitive drum.
3
Aperture
The aperture regulates the shape of the laser beam at the laser beam irradiation position.
4
LASER SAFETY
The beam of the semiconductor laser is itself extremely weak (about 120 mW), but focusing the
parallel rays results in an increase in energy to which extended exposure is hazardous.
The laser optical system of the digital plain paper copier is encased in metal which in turn is
housed in the external cover. There is thus no risk of leaks during use, nor during normal servic-
ing.
Note, however, extreme care must be exercised when servicing involves focusing the laser. Such
operations are hazardous and must not be attempted unless you are specifically trained to work
in this area.
The warning label shown below is attached on the left side of the upper inner cover.
[CAUTION]
•
Do not insert tools that are highly reflective into the path of the laser beam.
•
Remove all watches, rings, bracelets, etc.
(2) Galvanomirror
Four laser units are mounted on this scanning unit, and 4-line scanning is possible by scanning of
one plane of the polygonal mirror.
The galvanomirror controls the position of the laser beams in the secondary scanning direction so
that optimum pitch (42.3 µm) between the four laser beams can be maintained at all times.
DANGER – LASER RADIATION WHEN OPTICAL UNIT OPEN OR DRUM UNIT REMOVED
AND INTERLOCK DEFEATED. AVOID DIRECT EXPOSURE TO BEAM.
VORSICHT – LASERSTRAHLUNG, WENN DIE ABDECKUNG GEÖFFNET ODER
DIE TROMMEL ENTFERNT UND DIE VERRIEGELUNG UNWIRKSAM GEMACHT WIRD.
NICHT DIREKT DEM STRAHL AUSSETZEN.
DANGER – RAYON LASER LORSQUE LE BLOC OPTIQUE EST OUVERT, LE
TAMBOUR RETIRE ET LE VERROUILLAGE HORS D’USAGE.
EVITER L’EXPOSITION DIRECTE AU RAYON.
>PS<