Whentextor graphicsare sentby the computerto the printer,laser beamis generatedby a semiconductorlaser diode.Thisbeam is focusedby special scanningmirrorsthatturnthelightbeamintoa toolthat“writes”or’’pnnts” on the surfaceof the drum.The areasof the drumtouchedby thelaserbeam lose their negativecharge and containa reverseimage of the information sentfrom the computer.As the drumrotates,it passesa developerunitthat is also rotating,but in the oppositedirection.The surfaceof the developer unit is covered with toner (“ink”) which has a negative charge. The neutralizedportionsof the drum,containingthe informationto be printed, pick up negativelychargestoner from the developerunit.
At this point,paperfed fromthe papercassettemovesthroughthe transfer unit, from which it receives a positive charge. As the drum rotates, the negativelychargedparticlesof tonerare attractedto thepositivelycharged surfaceof the paper.
A combinationof heat andpressurefuse the imageto the paper.The paper is then ejectedfrom the printer.
Finally, a cleaningmechanismin the toner cartridgecleans excess toner tlom the drum, and a speciallightbeamneutralizesits entiresurface.Then the entireprocesscan begin again.
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