Toshiba DP120F, Service Manual

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DP120F/DP125F Mechanical Description 5-12 March 2000 © TOSHIBA TEC
3.3 Laser Scanner Area
3.3.1 Outline
The laser scanner area consists of the laser diode part, polygon part, and reflecting part.
The laser diode part generates a laser beam according to the laser diode drive signal sent from
the Main PBA. The laser beam is compensated to parallel rays through the Collimator lens and
then passes through the Slit and Cylinder lens. A laser beam of parallel rays is sent to the
polygon part. The laser diode part checks the current value flowed to the laser diode by each
line to keep the laser beam volume stable. The polygon part consists of the Polygon motor and
Polygon mirror. The Polygon motor turn the Polygon mirror at a uniform rate for laser beam
scanning. The laser beam generated in the laser diode part is sent to the reflecting part of the
Polygon mirror. The F
θ
lens and Reflecting mirror1, 2 bend the optical path of the laser beam
and then the beam is focused on the drum.
As the Polygon mirror turns at a uniform rate, the laser beam scans on the drum at a uniform
rate. This operation forms the image on the drum surface like a television.
The laser beam is also sent to the Start sensor by the Polygon motor and Polygon mirror.
Each time the Start sensor receives the laser beam, it sends a signal to the Main PBA. The
Main PBA uses this signal to determine the print start position of each line.
Fig. 5-3-4
05-03-04
Laser diode
unit
Collimator lens
Polygon motor
Drum
Start sensor
F
θ
lens
Polygon mirror
Cylinder lens
Slit
Reflecting
mirror 1
Reflecting
mirror 2