Brother MFC-7440N - Page 57

Ref. 2-22
Confidential
(2) Exposure
The laser beam radiated from the 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 drum is irradiated with reflected light and exposed. The
surface potential is lowered by such exposure and a latent image is formed.
Fig. Ref. 2-21
CO lensLaser diode
Laser unit
Exposure drum
Polygon mirror