Whentextor graphicsaresentby thecomputertothe printer,laserbeamis
generatedbyasemiconductorlaserdiode.Thisbeamis focusedby special
scanningmirrorsthatturnthelightbeaminto atoolthat“writes”or’’pnnts”
onthe surfaceofthedrum.The areasofthedrumtouchedby thelaserbeam
losetheir negativechargeand containareverseimage ofthe information
sentfromthe computer.Asthedrum rotates,itpassesadeveloperunitthat
is alsorotating,but inthe oppositedirection.Thesurfaceof the developer
unit is covered with toner (“ink”) which has anegativecharge. The
neutralizedportionsofthe drum,containingtheinformationtobe printed,
pickup negativelychargestoner fromthedeveloperunit.
Atthis point,paperfed fromthepaper cassettemovesthroughthetransfer
unit, from whichit receives apositivecharge. As the drum rotates,the
negativelychargedparticlesoftonerareattractedto the positivelycharged
surfaceof thepaper.
Acombinationofheatand pressurefusetheimageto thepaper. Thepaper
isthen ejectedfrom theprinter.
Finally,acleaningmechanismin the toner cartridge cleansexcesstoner
tlomthe drum,andaspeciallightbeam neutralizesitsentiresurface.Then
theentire processcanbegin again.
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