PrintersPrinters

Impact PrintersImpact Printers

Dot MatrixDot Matrix Daisy WheelDaisy Wheel

InkJet PrintersInkJet Printers

Eject Ink through tiny Eject Ink through tiny tubes called jets.tubes called jets.

Usually there are four Usually there are four ink wells: Cyan, ink wells: Cyan, Magenta, Yellow and Magenta, Yellow and BlackBlack

Resolution: How close Resolution: How close the little dots can bethe little dots can be

Speed: pages per Speed: pages per minute. B&W usually minute. B&W usually faster than colorfaster than color

Dye Sublimation PrintersDye Sublimation Printers

AKA thermal dye AKA thermal dye transfertransfer

Used in high-end Used in high-end applications (photos, applications (photos, publishing, medical)publishing, medical)

Continuous toneContinuous tone Rivals photo lab Rivals photo lab

processing from processing from negative filmnegative film

Laser PrintersLaser Printers

Electro-photographic Electro-photographic PrintingPrinting

Uses photo-conductive Uses photo-conductive materials to “etch” an materials to “etch” an image using a laser image using a laser beam.beam.

Very high quality print Very high quality print and graphics.and graphics.

Usually black and Usually black and white.white.

Toner CartridgeToner Cartridge

Contains Toner!!!Contains Toner!!! Also contains many Also contains many

other parts:other parts: Photosensitive Photosensitive

DrumDrum Primary Corona Primary Corona

(Charging Roller)(Charging Roller) Developing CylinderDeveloping Cylinder

Photosensitive DrumPhotosensitive Drum

Aluminum cylinderAluminum cylinder Coated with photosensitive particlesCoated with photosensitive particles Cylinder is grounded, particles are not.Cylinder is grounded, particles are not. Particles are charged.Particles are charged. When laser strikes the photosensitive When laser strikes the photosensitive

drum, the charged particles “escape” drum, the charged particles “escape” to the grounded cylinderto the grounded cylinder

Erase LampErase Lamp

Exposes all of the photosensitive Exposes all of the photosensitive drum to light.drum to light.

Leaves drum electrically neutral (i.e. Leaves drum electrically neutral (i.e. ground)ground)

Primary CoronaPrimary Corona

Very Close but not touching the Very Close but not touching the Photosensitive DrumPhotosensitive Drum

Handles extremely high voltage.Handles extremely high voltage. Transfers a uniform negative voltage Transfers a uniform negative voltage

(-600 to -1000 Volts) to (-600 to -1000 Volts) to Photosensitive DrumPhotosensitive Drum

TonerToner

Toner is plastic covered ironToner is plastic covered iron Toner is charged (via developing Toner is charged (via developing

cylinder) to about -200 Voltscylinder) to about -200 Volts Toner is uniformly distributed on the Toner is uniformly distributed on the

developing cylinder (held there by developing cylinder (held there by magnetism.magnetism.

Toner is attracted to photosensitive Toner is attracted to photosensitive drum where laser has hit.drum where laser has hit.

Laser Printing Large BlockLaser Printing Large Block

Transfer CoronaTransfer Corona

Charges the paper to attract the Charges the paper to attract the toner from the photosensitive drum.toner from the photosensitive drum.

This is usually a very thin wire This is usually a very thin wire applying a positive charge to the applying a positive charge to the paper.paper.

Prone to getting dirty. Prone to getting dirty. Must be cleanedMust be cleaned Very fragile. Very fragile. DON’T BREAK!!!!!!DON’T BREAK!!!!!!

Fuser AssemblyFuser Assembly

Consists of two slippery (Teflon) Consists of two slippery (Teflon) rollers (sometimes hidden) and a rollers (sometimes hidden) and a heater.heater.

One roller is heated, presses down on One roller is heated, presses down on the paper, melts the toner into the the paper, melts the toner into the paper.paper.

Other PartsOther Parts

Turning Gears: Turning Gears: moves the paper and moves the paper and rollersrollers

Power Supplies: Power Supplies: primary power runs primary power runs motors, electronics and transfer corona. motors, electronics and transfer corona. High voltage Supply for primary corona.High voltage Supply for primary corona.

System Board: System Board: processor, RAM, ROM, processor, RAM, ROM, BIOS, Control CircuitsBIOS, Control Circuits

Ozone Filter: Ozone Filter: eliminates Oeliminates O33

Sensors/Switches: Sensors/Switches: monitors status. monitors status. Stops FiresStops Fires

Printer LanguagesPrinter Languages

ASCII: American Standard Code for Information ASCII: American Standard Code for Information Interchange (Text and control)Interchange (Text and control)ascii.txtascii.txt

PostScript: created by Adobe. Printer PostScript: created by Adobe. Printer independent language. Strengths were independent language. Strengths were high resolution graphics and scalable high resolution graphics and scalable fonts. fonts. sigcse97.txtsigcse97.txt

Printer Control Language: created by HP. Printer Control Language: created by HP. Originally for text. PCL6 supports scalable Originally for text. PCL6 supports scalable fonts and drawing funtions.fonts and drawing funtions.

Graphical Device InterfaceGraphical Device Interface

Microsoft print handling componentMicrosoft print handling component Uses the CPU (not the printer) to Uses the CPU (not the printer) to

process a print job.process a print job. Sends a “Raster” image to the Sends a “Raster” image to the

printer.printer.

Printer ConnectionsPrinter Connections

Parallel Port: Uses Parallel Port: Uses special cable to special cable to connect 25-pin connect 25-pin printer port on printer port on computer to 36-pin computer to 36-pin Centronics port on Centronics port on printer.printer.

USB: Plug and USB: Plug and Play???Play???

InfraRedInfraRed

IEEE 1284 StandardIEEE 1284 Standard

Specifies Cable and Electronics Specifies Cable and Electronics configuration.configuration.

Centronics Mode: One way 8-bits Centronics Mode: One way 8-bits Nibble mode: uses status wires to send 4-Nibble mode: uses status wires to send 4-

bit data back to computerbit data back to computer Byte Mode/BiDir: enables half-duplex 8-bit Byte Mode/BiDir: enables half-duplex 8-bit

communicationcommunication Enhanced Parallel Port: Offloads overhead Enhanced Parallel Port: Offloads overhead

to parallel port away from CPU.to parallel port away from CPU. ECP: uses DMA and data compression (run ECP: uses DMA and data compression (run

length encoding)length encoding)

Six Steps of Laser PrintingSix Steps of Laser Printing

1.1. CleaningCleaning

2.2. Charge/ConditionCharge/Condition

3.3. WritingWriting

4.4. DevelopingDeveloping

5.5. TransferringTransferring

6.6. FusingFusing

Take place inside Take place inside toner cartridgetoner cartridge

Use components that Use components that undergo the most undergo the most wearwear

Side ViewSide View

Step 1: CleaningStep 1: Cleaning

Step 1 Mind-Numbing DetailStep 1 Mind-Numbing Detail

Sweeper strip cleans Sweeper strip cleans the drumthe drum

Remove/swept away Remove/swept away by Sweeping bladeby Sweeping blade

Cleaning Blade Cleaning Blade finishes physical finishes physical cleaningcleaning

Erase lamps remove Erase lamps remove electrical chargeelectrical charge

Step 2: ConditioningStep 2: Conditioning Primary Charging Roller conditions drum to Primary Charging Roller conditions drum to

contain a contain a Uniform Uniform high electrical charge (-600 V)high electrical charge (-600 V)

Step 3: WritingStep 3: Writing

Laser beam discharges a lower Laser beam discharges a lower charge to only those places where charge to only those places where toner is to gotoner is to go

Writing Mind-numbing Writing Mind-numbing DetailDetail

Uniform charge is discharged only where the Uniform charge is discharged only where the laser beam hits (due to photosensitivity)laser beam hits (due to photosensitivity)

Mirrors reflect the laser beam onto the DrumMirrors reflect the laser beam onto the Drum Scanning Mirror directs beam across the pageScanning Mirror directs beam across the page Main mirror(as wide as the page) reflects beam onto Main mirror(as wide as the page) reflects beam onto

drum through a slitdrum through a slit Focusing lens sharpens the imageFocusing lens sharpens the image Beam detect causes DC controller to step the Beam detect causes DC controller to step the

drum and start a new scandrum and start a new scan

Step 4: DevelopingStep 4: Developing

Toner is placed onto the drum where Toner is placed onto the drum where the charge has been reducedthe charge has been reduced

Developing Mind-numbing Developing Mind-numbing DetailDetail

Charged (~-300V) Toner (resin coated Charged (~-300V) Toner (resin coated iron) is attracted to the developing iron) is attracted to the developing cylinder magneticallycylinder magnetically

Control blade creates even distributionControl blade creates even distribution Charged Toner is pulled off developing Charged Toner is pulled off developing

cylinder onto drumcylinder onto drum Toner is charged by DC bias on Dev.Cyl. Toner is charged by DC bias on Dev.Cyl.

The amount of bias controls densityThe amount of bias controls density

Step 5: TransferringStep 5: Transferring Strong electrical charge draws toner Strong electrical charge draws toner

off drum onto paper; takes place off drum onto paper; takes place outside the cartridgeoutside the cartridge

TransferingTransfering

As paper is feed to roller a transfer As paper is feed to roller a transfer charging roller creates a positive chargecharging roller creates a positive charge

As paper passes by drum, the toner is As paper passes by drum, the toner is drawn to the positively charged paperdrawn to the positively charged paper

After paper passes roller the static After paper passes roller the static charge eliminator reduces the charge charge eliminator reduces the charge on the paper and the drumon the paper and the drum

Step 6: FusingStep 6: Fusing

Heat and pressure fuse toner to Heat and pressure fuse toner to paperpaper

Fusing Mind-numbing detailFusing Mind-numbing detail

Fusing roller apply heat and Fusing roller apply heat and pressure.pressure.

Toner melts into paperToner melts into paper If temperature exceeds 410 degrees If temperature exceeds 410 degrees

F the fusing system shuts downF the fusing system shuts down

The EndThe End