Whentextor graphicsaresentbythecomputerto theprinter,laserbeamis
generatedby asemiconductorlaserdiode.Thisbeamis focusedby special
scanningmirrorsthatturnthelightbeamintoatoolthat“writes”or’’pnnts”
onthesurfaceofthedrum.Theareasofthedrumtouchedbythelaserbeam
lose theirnegativechargeandcontaina reverseimageof the information
sentfromthecomputer.Asthedrumrotates,it passesa developerunitthat
is alsorotating,butin theoppositedirection.Thesurfaceof thedeveloper
unit is covered with toner (“ink”) which has a negative charge. The
neutralizedportionsof thedrum,containingthe informationto be printed,
pickup negativelychargestonerfromthedeveloperunit.
Atthispoint,paperfed fromthepapercassettemovesthroughthetransfer
unit, from which it receivesa positivecharge.As the drum rotates,the
negativelychargedparticlesoftonerareattractedto thepositivelycharged
surfaceof the paper.
A combinationof heatandpressurefusetheimageto thepaper.Thepaper
is thenejectedfromtheprinter.
Finally,a cleaningmechanismin the toner cartridgecleans excesstoner
tlomthedrum,anda speciallightbeamneutralizesitsentiresurface.Then
theentireprocesscanbeginagain.
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