Ricoh B230 Training Program page 84

Shutter
Open
The shutter stops dust and toner from entering the laser optics unit.
The shutter opens when the polygon motor starts, and closes after
the polygon motor stops.
The motor moves the shutter through a cam.
Two sensors detect when the shutter is open and closed.
This mechanism makes sure that the shutter is only open when the laser is writing. At
all other times, the shutter is closed, to stop dust and toner getting in.
Shutter
Shutter
Closed Cam
Shutter
Motor
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