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1.2.5The Printengine
It’sthe print engine that-formsthe actualcharactersand graphics.The
enginedirectsitslaser,apinpointstreamoflightpulses,throughmirrorsand
lensesontothe surfaceof apositively-chargedrotatingdrum.
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Mirror
Lens
Laserbeam
~%a~nirr~ mirror
nductor laserdiode
Photosensitive drum
Asthelaserscans,it “draws”thepage-mapstoredinyourprinter’smemory.
Whereveralightpulsestrikes,that tinypartof the drumdropsto aneutral
electricalcharge. Thatspot then attracts finetoner powder as the drum
rotatespastthe powdercompartment.
Asthedrum rotatesfurtheritmeetsthepaper.The paperitselfisnegatively
chargedbypassingbyafinecoronawire. Sinceoppositechargesattract,the
negativepaperclingsto the positivedrum.Thenheat andpressurefrom a
rollermeltor~usethedotsoftonerontothe paper,preciselyreproducingthe
image.
Finallythepaperslidesintotheoutputbin.Thepaperusuallycomesoutface
downso it stacksin the correctsequence.
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