MELJUN CORTES computer organization_lecture_chapter_20

Chapter 20

Printers

MELJUN CORTESMELJUN CORTES

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

OverviewIn this chapter, you will learn to

Describe current printer technologies

Explain the laser printing process

Install a printer on a Windows PC

Recognize and fix basic printer problems

CompTIA A+Essentials

Essentials

Getting the Right Sound Card

Printer Technologies


Impact Printers Impact printers leave an image on the

paperPhysically strike an inked ribbon against the

surface of the paper

Relatively slow and noisy

Used for multipart formsPoint of sale receiptsOffices


Dot-Matrix Printers Dot-matrix printers

Use an array of pins known as printwires to strike an inked printer ribbon and produce images

The case that holds the print wires is called the printhead

Use either 9-pin (draft quality) or 24-pin (letter or near-letter quality)


Inkjet Printers Inkjet printers

Simple devices that consist of the following:Printhead, support electronics, a transfer mechanism,

and a paper-feed component

Work by ejecting ink through tiny tubes Ink is heated by tiny resistors or electroconductive

plates at the end of each tubeThe resistors or plates boil the ink, which creates a tiny

air bubble that ejects a droplet of ink onto the paperSome inkjets use mechanical methods to eject ink

Most color printers are ink-jet and produce a high-quality image


Inside an Inkjet Printer


Inkjet Key Features• Print resolution

– Density of the ink– Dots per inch (dpi)

• Print speed– Pages per minute

(ppm)

• Can print to almost anything


Dye-Sublimation PrintersDye-sublimation printers (or thermal dye

transfer printers) use sublimation

Sublimation causes something to change from a solid form into a vapor and then back into a solid

Used for fine detail and rich color

One pass for each color

Produces high-quality output


Thermal PrintersThermal printers

Same as first generation of fax machines

Two types: direct thermal and thermal wax

Use a heated printhead to burn dots into the surface of special heat-sensitive paper

Still used for receipts at some businesses


Laser Printers Laser printers use a mechanism called

electro-photographic imaging

Produce high-quality and high-speed output of both text and graphics

More expensive than inkjet or impact printers

Use lasers as a light source


Laser Printer Parts Toner cartridge

Holds the tonerMany other parts that suffer the most wear

and tear contained in toner cartridge

Photosensitive drum Aluminum cylinder coated with particles of

photosensitive compounds

Erase lampExposes the entire surface

of the photosensitive drum to light


Laser Printer PartsPrimary corona

Enables voltage to pass to the drum and charge the photosensitive particles on its surface

LaserActs as the writing mechanism of the printer

TonerFine powder made up of plastic particles bonded

to iron particles


Laser Printer PartsTransfer corona

Applies a positive charge to the paper

FuserAttaches the toner

permanently to the paper using the pressure roller and heated roller

Fuser assembly Fuses the toner to the paper


Laser Printer Components


Laser Printer PartsPrimary power supply

Provides power to the motors that move the paper, system electronics, and transfer corona

High-voltage power supply Provides power to the primary coronaWhen inserting a new toner cartridge, always

turn the laser printer off before opening it

Turning gearsDiscrete units called gear packs or gearboxes


Laser Printer PartsSystem board

Contains the main processor, ROM, and RAMROM can often be “flashed”Not enough RAM results in memory overflow error

Ozone filter Ozone (O3) can damage printer componentsFilter needs to be replaced periodically

Sensors and Switches Detects paper jams, empty paper trays, low toner

levels, and so on


Solid Ink PrintersUse solid sticks of nontoxic “ink”

Produces vibrant color

Ink is melted and absorbed into the paper fibers

Only needs a single pass

More expensive than other printersBut ink sticks are significantly less expensive

than inkjet cartridges


Printer Languages American Standard Code for Information

Interchange (ASCII) Basic alphanumeric characters and a variety of

control codes for transferring data and controlling printers

Limited in its capability

The PostScript page description language (PDL) developed by AdobeDevice-independent printer language capable of

high-resolutions and scalable fontsPrinters print faster because most of the image

processing is done by the printer and not the PCPostscript files are very portable


Printer Languages Hewlett Packard developed the Printer control

language (PCL)Expanded set of printer commandsDependent on the printer hardwareDoes not support advanced graphical functionsDoes not define the page as a single raster image

Windows 2000/XP uses the Windows graphical device interface (GDI)The operating system handles print functionsIf the printer has a capable raster image

processor and enough RAM, you don’t need to worry about the printer language


Printer ConnectivityMost printers connect to one of two ports on

the PCDB-25 parallel portUSB port

The parallel port was a lot faster than the existing serial ports at the timeSlow by today’s standards with a maximum data

transfer rate of 150 KBpsIEEE (Institute of Electrical and Electronics

Engineers) 1284 standard addressed standardizing parallel ports


IEEE 1284 Standard The IEEE 1284 standard requires

Support for five modes of operationCompatibility mode, nibble mode, byte mode, EPP, ECP

Standard methods of negotiation for determining which modes are supported

A standard physical interface

A standard electrical interface


Parallel Connections, Cabling, and Electricity

A standard printer cable A male DB-25 connector on one end and a 36-

pin Centronics connector on the other

Acceptable for transferring data at 150 KBps at distances of less than

six feet

IEEE 1284-compliantcableCan be up to 32 feet


USB and FireWire PrintersMost new printers now use USB

connectionsMost use USB type A on one end and USB

type B on the other end

FireWireWorks as easily as USB

USB B

USB A


Network and Other PrintersPrinters can be connected on a network

Needs NIC and connection (typically RJ-45)Needs IP address (either manually assigned

or automatically assigned from DHCP)Can be connected to print serverSome also have wireless and Bluetooth

capabilities

Other printersRare, but may see serial or SCSI printers


IT TechnicianCompTIA A+Technician

The Laser Printing Process


Physical Side of the ProcessCalifornia Cows Won’t Dance The Fandango

CleanChargeWriteDevelopTransferFuse


Clean the Drum Printing process begins by physically and electrically

cleaning the photosensitive drum

• Physically by scraping the surface of the drum with a rubber cleaning blade

• Electrically with an erase lamp to completely discharge any particles


Charge the Drum Next the drum is charged by applying a negative

charge to the entire surface

• Charged by primary corona wire

• Between ~600 and ~1000 volts


Write and Develop the Image A laser is used to write and develop an image

on the surface of the drum

• Every particle hit by the laser will release most of its negative charge into the drum


Transfer the Image Using the transfer corona, the paper is

charged positively

• The negatively charged toner particles leap from the drum to the paper


Fuse the Image Image fused to the paper

• The heat roller made of a nonstick material and the pressure roller are used to fuse the image onto the paper

• Toner particles melted into the page

• Static charge eliminatorremoves charge from paper

• Stops paper from stickingto drum


The Electronic Printing ProcessRaster image

Laser printers generate a raster image of the page

A raster image is a pattern of dots

Raster image processor (RIP) chip translates the raster image into commands for the laser


The Electronic Printing ProcessRIP needs RAM in order to store this data

Mem Overflow error indicates insufficient RAM- Add RAM, reduce the resolution, or print smaller graphics

HP LaserJet 21 error means the data is too complex - Reduce complexity by using fewer fonts and less formatting, reducing graphics resolution, and so on

Resolution enhancement technology (RET) Enables the printer to insert smaller dots among the

characters to smooth out jagged curves

Disabling RET helpsMEM OVERFLOW errors


The Electronic Printing ProcessResolution

A laser printer can print at different resolutions

Resolution is expressed in dots per inch (dpi) such as 600 x 600 or 1200 x 1200 dpi

The first number is the horizontal resolution—how fine a focus can be achieved by the laser

The second number is the vertical resolution—the smallest increment by which the drum can be turned

Installing a Printer in Windows


Printing in Windows 2000/XPWindows 2000/XP

The physical printer is called a print deviceThe printer is a program that controls one or

more print devicesOne printer can support more than one print

devicePrint driversPrint spooler


Setting Up Printers PnP devices usually works after plugging them

inIf necessary, can use applets to install

Open the Printers appletWindows XP: Start Printers and FaxesWindows 2000: Start Settings PrintersOr find applet in Control Panel

Click the Add Printer icon to start the Add Printer Wizard


Setting Up PrintersAdd Printer wizard

Select local or network printerSelect a printer port


Setting Up PrintersAdd Printer Wizard

Add the driverWindows Update easiest to use (if driver

installed)Or can download driver from manufacturer or

use CD accompanying printer and use Have DiskCheckmark indicates default printer


Optimizing Print Performance

Printout may not match screen colorsMonitors use RGBPrinters use CMYKBoth don’t always match exactly

CalibrationManually calibrate monitor

Print a test image and adjust monitor to match printoutAutomatically calibrate printer

Use an International Color Consortium (ICC) color profileInstructs the printer to print colors a certain way

Troubleshooting Printers


General Troubleshooting IssuesTools of the trade

Multimeter

Cleaning solutions such as denatured alcohol

Extension magnet for retrieving loose screws

CD or USB drive with test patterns

Phillips-head or flat-head screwdriver


General Troubleshooting IssuesJob never prints

Is the printer on? Connected? Does it have paper?

Check the spooler status Can bypass spooler if desired

Strange sizesPoints to setup errorCheck the Page Setup

option in the application


General Troubleshooting IssuesMisaligned or garbage prints

A corrupted or incorrect driver—reinstall

You may have asked the printer to do something it can’t do, such as printing Postscript with a PCL driver

ConsumablesPrinter components should be properly disposed

of to avoid environmental hazards

Some companies buy used toner cartridges


Other IssuesSharing multiple

printers

A mechanical switch box may be used to share multiple printers

Laser printers should only be used with electronic switch boxes

Crashes on power up

Printers require a lot of power on start up

HP recommends that you turn on the laser printer first and then the PC


Troubleshooting Dot Matrix Printers Dot-matrix printers require regular maintenance

The printhead and the platen should be cleaned with denatured alcohol

Prevents problems such as white bars on text, dots and smudges on paper, and so on

Gears and pulleys should be lubricated according to the manufacturer’s specifications

Bad-looking textDirty or damaged printheadClean with denatured alcohol or replace

Bad-looking pageClean the platen with denatured alcoholReplace the ribbon


Troubleshooting Inkjet PrintersUse the maintenance software that came with

the printer setup programAlign and clean the print heads

Ink will dry out in a short time if an inkjet printer is not used—the ink in the tiny nozzles of the printhead dries out

Multisheet grabFan the paperLet the printer rest if you’ve been printing a lotHumidity can be an issue

Clean the small tank where the printhead rests or parks with a paper towel


Troubleshooting Laser PrintersPrint a diagnostic print page as a first-step in

troubleshootingHold down the On Line button as the printer is started as

a first step in troubleshooting

Blank paperOut of tonerPrint a diagnostic page, remove the toner cartridge, and

look at the imaging drum—if an image is there, the transfer corona or high-voltage power supply is bad


Laser Printer MaintenanceKeep printer clean

Excess toner and paper dust commonly cause the printer to get dirty

Clean with a special low-static vacuum designed for electrical components or a can of compressed air

The rubber guide rollers will pick up dirt and paper dust over time, which causes paper jams


Laser Printer MaintenanceCertain components should be replaced

regularly

Follow manufacturers recommendations

Most manufacturers sell maintenance kits for most of their printers

Clean or replace ozone filters regularly

Check and clean fuser assembly and heat roller


Troubleshooting Laser PrintersBlank Paper

May be out of tonerCheck the imaging drum to see if image is on

drum but just not transferred to paperCould be transfer corona or high-voltage

supply

Dirty printoutsLight dusting of toner on the paper (front or

back) indicates dirty printerClean the printer


Troubleshooting Laser Printers

Ghosting

Can be light ghosting or dark ghostingLight ghosting explored on next slide

Dark ghosting can be from a damaged drum—replace the toner cartridge

Low temperature or low humidity can aggravate ghosting problems


Troubleshooting Laser PrintersLight ghosting

Caused by printing an extremely dark or complex image

Referred to as developer starvationLower the resolutionUse different patternAvoid 50% grayscale and dot-on/dot-off patternsChange the layout so grayscale patterns do not follow

black areasMake dark patterns lighter and light patterns darkerPrint in landscapeAdjust print density and RET settingsPrint a completely blank page before the next one


Troubleshooting Laser PrintersVertical white lines

Clogged tonerTry shaking the toner cartridge or replacing it

Blotchy printUneven dispersion of tonerTry shaking the toner cartridge from side to sideMake sure the printer is levelMake sure the paper is not wet in spotsCheck the fusing rollers and photosensitive drum

for foreign objects


Troubleshooting Laser PrintersSpotty print

Try wiping off the fuser rollersCheck the drum for damage

Embossed effectLike putting a penny under a piece of paper

and rubbing it with a lead pencilA foreign object on a rollerA foreign object on the photosensitive drumReplace the toner cartridge


Troubleshooting Laser PrintersIncomplete characters

These may occur on transparenciesTry adjusting the print density

Creased pagesCotton bond paper is more susceptibleTry using a different paper type


Troubleshooting Laser PrintersPaper jams

Do not pull on the paper to remove itCan damage the printer by pulling jammed paper outCheck manufacturer's jam removal procedure

If there is no jammed paper, sensors may be bad

Pulling multiple sheetsTry using a different ream of paper—if that works,

the issue is humidityCheck the separation pad—a small piece of

rubber or cork that separates the sheets as they are pulled from the paper tray


Troubleshooting Laser PrintersWarped, overprinted, or poorly formed characters

Paper that is too rough or too smoothDon’t open a ream of paper until it is loaded into the

printerAlways fan the paper before loading it in the printerDo a printer self-test to determine if it is the printer or

the computerReplace the toner cartridge, check the cabling,

replace the data cableTurn off advanced functions and high-speed settings

to see if they may not be supported by your software configuration


Beyond A+—DOT4Also called IEEE 1284.4 standard

Created for multifunction peripherals (MFP)Devices that combine printer, fax, and

scanner in one piece of equipment

Allows simultaneous sending and receiving across a single physical channel


Technology

MELJUN CORTES computer organization_lecture_chapter_20