PRINTERS

A DEVICE THAT PRINTS TEXT OR ILLUSTRATIONS ON PAPER.THERE ARE MANY DIFFERENT TYPES AND BRANDS OF PRINTERS.DEPENDING ON THE TECHNOLOGY USED.THE OUTPUTS PRODUCED BY PRINTERS ARE NEAR LETTER QUALITY ( AS GOOD AS A TYPEWRITER ) OR DRAFT QUALITY.THE SPEED OF PRINTERS ARE MEASURED IN CHARACTERS PER SECOND OR PAGES PER MINUTE.THEY ARE ALSO DESCRIBED AS BEING IMPACT OR NON IMPACT.IMPACT PRINTERS INCLUDE ALL PRINTERS THAT WORK BY STRIKING AN INK RIBBON.NON IMPACT PRINTERS ARE THOSE THAT TRANSFER THE TEXT OR ILLUSTRATION WITHOUT THE USE OF A RIBBON.

DOT MATRIX PRINTERS

CREATES CHARACTERS BY STRIKING PINS AGAINST AN INK RIBBON.EACH PIN MAKES A DOT,AND COMBINATIONS OF DOTS FORM CHARACTERS AND ILLUSTRATIONS.THIS PROCESS MAKES THEM AN IMPACT PRINTER.THE MOST COMMON NUMBER OF PINS ARE 9, 18, AND 24.A 24 PIN PRODUCES NEAR LETTER QUALITY.BUT IF YOU LOOK CLOSELY,YOU CAN SEE THE DIFFERENCE.DOT MATRIX PRINTERS WITH LESS THAN 24 PINS ARE ONLY CAPABLE OF DRAFT QUALITY.THEY CAN PRINT UP TO 500cps(CHARACTERS PER SECOND).DURING PREVENTIVE MAINTENANCE NEVER LUBRICATE THE PRINTHEAD OF THE PRINTER. ALSO NEVER TOUCH THE PRINTHEAD.THEY GET VERY HOT.MOST USEFUL WHEN YOU NEED TO PRINT CARBON COPIES LIKE RECEIPTS OR SHIPPING INVOICES.

INKJET ( BUBBLEJET ) PRINTERS

ARE NON IMPACT PRINTERS.THEY SPRAY INK AT A SHEET OF PAPER, FROM A INK RESERVOIR IN A DISPOSABLE CARTRIDGE.WHICH ALSO CONTAINS THE PRINTING MECHANISM.PRODUCING HIGH QUALITY TEXT AND ILLUSTRATIONS.THE SPRAYING IS ACCOMPLISHED BY USING AN INK STREAM PROCESS WHICH HAS TINY NOZZLES,(AS MANY AS 50).THE PRINT QUALITY IS RATED IN DOTS PER INCH,(dpi). MORE DOTS BETTER THE IMAGE.THEY CONTAIN A PIEZOELECTRIC CRYSTAL THAT EXPANDS FORCEING THE INK OUT WHEN SIGNALED.

LASER PRINTERS

CONSIDERED PAGE PRINTERS BECAUSE THEY RECEIVE AND PRINT TEXT AND ILLUSTRATIONS FOR ONE PAGE AT A TIME.THEY PRODUCE VERY HIGH QUALITY TEXT AND ILLUSTRATIONS.RANGEING FROM 4 TO 20 TEXT PAGES PER MINUTE. NATURALLY THEY ARE NON IMPACT PRINTERS

SIX STEPS TO LASER PRINTING

1) CLEANING :

BEFORE A PAGE IS STRATED,ANY REMNANTS OF A PREVIOUS PAGE ARE CLEARED AWAY.THE DRUM IS SWEPT FREE OF ANY LINGERING TONER WITH A RUBBER BLADE,AND A FLUORESCENT LAMP REMOVES ANY ELECTRICAL CHARGE REMAINING ON THE DRUM.ANY TONER REMOVED IN THIS STEP IS NOT REUSED BUT PUT INTO A USED TONER COMPARTMENT ON THE CARTRIDGE.THE EP (ELECTROPHOTOGRAPHIC) DRUM HAS TO BE CLEANED BEFORE IT CAN TAKE ON A NEW IMAGE.IN BRIEF THE EP DRUM IS CLEANED WITH A RUBBER BLADE

2) CONDITIONING :

THE ENTIRE DRUM IS UNIFORMLY CHARGED TO -600V BY THE PRIMARY CORONA WIRE.ALSO KNOWN AS THE MAIN CORONA.WHICH IS LOCATED INSIDE THE TONER CARTRIDGE.THIS CHARGE CONDITIONS THE DRUM FOR THE NEXT STEP.

3) WRITING :

THE LASER PRINTER CONTROLLER USES A LASER BEAM AND A SERIES OF MIRRORS TO CREATE THE IMAGE OF THE PAGE ON THE DRUM.THE LASER BEAM IS TURNED ON AND OFF IN ACCORDANCE WITH THE IMAGE TO BE CREATED ON THE DRUM.WHERE THE LASERS LIGHT CONTACTS THE PHOTOSENSITIVE DRUM,THE CHARGE AT THAT POINT IS REDUCED TO ABOUT -100V.AFTER THE IMAGE HAS BEEN TRANSFERED TO THE DRUM THIS WAY.THE CONTROLLER ALSO STARTS THE PAGE SHEET THROUGH THE PRINTER,STOPPING IT AT THE REGISTRATION.IN BRIEF A LASER BEAM WRITES TO THE EP DRUM,THIS LASER CAUSES PORTIONS OF THE DRUM TO BECOME ALMOST POITIVELY CHARGED

4) DEVELOPING :

THE DEVELOPING ROLLER LOCATED INSIDE THE TONER CARTRIDGE,HAS A MAGNET INSIDE OF IT THAT ATTRACTS THE IRON PARTICLES IN THE TONER.AS THE DEVELOPING ROLLER ROTATES BY THE DRUM,THE TONER IS ATTRACTED TO THE AREAS OF THE DRUM THAT HAVE BEEN EXPOSED BY THE LASER,CREATING THE PRINT IMAGE ON THE DRUM.IN BRIEF TONER IS APPLIED TO THE DRUM BY THE PARTICLES BEING TRANSFERED TO THE AREAS OF THE POSITIVE CHARGE.

5) TRANSFERING :

THE BACK OF THE PAPER SHEET IS GIVEN A POSITIVE CHARGE BY THE TRANSFER CORONA WIRE.THAT ATTRACTS THE NEGATIVELY CHARGED TONER FROM THE DRUM ONTO THE PAPER AS IT PASSES.AFTER THIS STEP THE PAPER HAS THE IMAGE OF THE PAGE ON IT.BUT THE TONER WHICH IS HELD ONLY BY SIMPLE MAGNETISM,IS NOT YET BONDED TO IT.A STATIC CHARGE ELIMINATOR PREVENTS THE PAPER FROM WRAPPING AROUND THE DRUM DURING THIS STEP.IN BRIEF THE TRANSFER CORONA WIRE CHARGES THE PAPER WITH A POSITIVE CHARGE.THE EP DRUM TURNS AS THE PAPER RUNS BENEATH IT.

6) FUSING :

THE FUSING ROLLERS APPLY HEAT AND PRESSURE TO THE TONER.MELTING AND PRESSING IT INTO THE PAPER TO CREATE A PERMANENT BOND.THE FUSING ROLLERS ARE COVERED WITH TEFLON AND TREATED WITH A LIGHT SILICON OIL TO KEEP THE PAPER FROM STICKING TO THEM.THE HEAT DURING THIS PROCESS IS 350 DEGREES F.THE PAPER WITH THE FINAL IMAGE IS ROLLED OUT OF THE PRINTER.THEN THE ERASER LAMP IS TURNED ON NEAR THE SURFACE OF THE EP DRUM ALLOWING IT TO LOOSE ITS CHARGE.

EXTRA PRINTER INFORMATION :

TRANSFER CORONA :

POSITIVELY CHARGES THE PAPER SO THE IMAGE CAN BE TRANSFERED FROM THE DRUM TO THE PAPER.

PRIMARY CORONA :

MOVES THE TONER FROM THE TONER CARTRIDGE ONTO THE DRUM.

DRUM ON A LASER PRINTER :

IS PHOTOSENSITIVE.DO NOT EXPOSE TO SUNLIGHT.

LASER PRODUCES :

A GAS CALLED OZONE,THAT IS CAPTURED BY A FILTER.REPLACE OR CLEAN WHEN PERFORMING MAINTANCE.GO BY MANUFACTURE.

TONER IS :

A COMBINATION OF VERY FINE PARTICLES OF IRON AND PLASTIC.

NEVER PLUG A LASER PRINTER :

INTO A CONVENTIONAL PC UPS,( UNINTERRUPTIBLE POWER SUPPLY ),THEY DRAW A HUGE AMOUNT OF POWER AT START UP,AND VERY FEW UPSs CAN HANDLE THE DEMAND.

FOUR ROLLERS OF PAPER TRANSPORT :

FEED, REGISTRATION, FUSER, AND EXIT ROLLER

LASER PRINTERS TWO POWER SUPPLIES :

PRIMARY POWER SUPPLY:

PROVIDES POWER TO THE MOTORS THAT MOVE THE PAPER,SYSTEM ELECTRONICS,LASER,AND TRANSFER CORONA.

HIGH VOLTAGE POWER SUPPLY :

CONVERTS AC CURRENT INTO HIGHER VOLTAGES USED BY THE PRIMARY CORONA.

NEVER USE LASER PRINTERS :

WITH A SWITCHBOX,THE POWER SURGE THEY CREATE CAN DAMAGE PRINTERS.