Brother DCP-9045CDN Reference Manual page 54

2. Exposure
Four laser beams radiated from a laser diode inside the laser unit are concentrated into a
constant width by a slit in the CO lens cell and then reflected by a polygon mirror rotating at
high speed. The evenly charged exposure drum is irradiated with reflected light and exposed.
Surface potential is lowered by such exposure and an Electrostatic latent image is formed.
Laser diode
CO lens
* View from the right side
Exposure drum (K)
* View from top
CO lens
Exposure drum (Y)
Fig. Ref2-26
Ref. 2-28
Laser diode
CO lens
Polygon mirror
Laser unit
Exposure drum (C)
Exposure drum (M)
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