meljun cortes computer organization lecture chapter20

7/27/2019 MELJUN CORTES Computer Organization Lecture Chapter20

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Chapter 20

Printers

MELJUN CORTES


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MELJUN CORTES

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

Overview

In 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


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CompTIA A+

Essentials

Essentials

Getting the Right Sound Card

Printer Technologies


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Impact Printers

Impact printersleave an image on the paper Physically strike an inked ribbon against the surface

of the paper

Relatively slow and noisy

Used for multipart forms

Point of sale receipts

Offices


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Dot-Matrix Printers Dot-matrixprinters

Use an array of pins known as printwiresto strikean inked printer ribbon and produce images

The case that holds the print wires is calledthe printhead

Use either 9-pin

(draft quality) or24-pin(letter ornear-letter quality)


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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 tube

The resistors or plates boil the ink, which creates a tiny airbubble that ejects a droplet of ink onto the paper

Some inkjets use mechanical methods to eject ink

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


7/61 2007 The McGraw-Hill Companies, Inc. All rights reserved

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 almostanything



Dye-Sublimation Printers Dye-sublimationprinters (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 andrich color

One pass for each color

Produces high-quality output



Thermal Printers

Thermal 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 printersuse 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 toner

Many other parts that suffer the most wear and tearcontained in toner cartridge

Photosensitive drumAluminum cylinder coated with particles of

photosensitive compounds

Erase lamp Exposes the entire surface

of the photosensitive drum to light



Laser Printer Parts

Primary corona

Enables voltage to pass to

the drum and charge the

photosensitive particles

on its surface

Laser

Acts as the writing mechanism of the printer

Toner

Fine powder made up of plastic particles bonded to

iron particles



Laser Printer Parts

Transfer coronaApplies 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 Parts

Primary 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 corona

When inserting a new toner cartridge, always turn the

laser printer off before opening it

Turning gears

Discrete units called gear packs or gearboxes



Laser Printer Parts

System board Contains the main processor, ROM, and RAM

ROM can often be flashed

Not enough RAM results in memory overflow error

Ozone filter

Ozone (O3) can damage printer components

Filter needs to be replaced periodically

Sensors and Switches

Detects paper jams, empty paper trays, low toner

levels, and so on



Solid Ink Printers

Use 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 printers

But ink sticks are significantly less expensive than

inkjet cartridges



Printer LanguagesAmerican Standard Code for Information

Interchange(ASCII) Basic alphanumeric characters and a variety of

control codes for transferring data and controllingprinters

Limited in its capability

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

high-resolutions and scalable fonts

Printers print faster because most of the imageprocessing is done by the printer and not the PC

Postscript files are very portable



Printer Languages Hewlett Packard developed the Printer control

language(PCL) Expanded set of printer commands

Dependent on the printer hardware

Does not support advanced graphical functions Does not define the page as a single raster image

Windows 2000/XP uses the Windows graphical

device interface(GDI) The operating system handles print functions

If the printer has a capable raster image processorand enough RAM, you dont need to worry aboutthe printer language



Printer Connectivity

Most printers connect to one of two ports on thePC

DB-25 parallel port

USB port

The parallel portwas a lot faster than the existing

serial ports at the time

Slow by todays standards with a maximum data

transfer rate of 150 KBps

IEEE (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 operation

Compatibility 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


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Parallel Connections, Cabling, and Electricity

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

Centronicsconnector on the other

Acceptable for transferring data at150 KBps at distances of less than

six feet

IEEE 1284-compliantcable

Can be up to 32 feet


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USB and FireWire Printers

Most new printers now use USB connections Most use USB type A on one end and USB type B

on the other end

FireWire

Works as easily as USB

USB B

USB A


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Network and Other Printers

Printers 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 server

Some also have wireless and Bluetooth capabilities

Other printers

Rare, but may see serial or SCSI printers


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IT Technician

CompTIA A+

Technician

The Laser Printing Process


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Physical Side of the Process

California Cows Wont Dance The Fandango Clean

Charge

Write

Develop

Transfer

Fuse


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Clean the Drum

Printing process begins by physically and electricallycleaning 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


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Charge the Drum

Next the drum is chargedby applying a negative charge tothe entire surface

Charged by primary corona wire

Between ~600 and ~1000 volts


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Write and Develop the Image

A laser is used to writeand developan image onthe surface of the drum

Every particle hit by

the laser will releasemost of its negative

charge into the drum


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Transfer the Image

Using the transfercorona, the paper is chargedpositively

The negatively charged toner particles leap from the

drum to the paper


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Fuse the Image

Image fused to the paper

The heat roller made of a nonstick material and the pressure

roller are used to fusethe image onto the paper

Toner particles meltedinto the page

Static charge eliminator

removes charge from paper

Stops paper from sticking

to drum


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The Electronic Printing Process

Rasterimage

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


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RIP 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 errormeans 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 helps

MEM OVERFLOW errors


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ResolutionA 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 resolutionhow fine a

focus can be achieved by the laser

The second number is the vertical resolutionthe smallest

increment by which the drum can be turned


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Installing a Printer in Windows


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Printing in Windows 2000/XP

Windows 2000/XP The physical printer is called a print device

The printeris a program that controls one or more

print devices

One printer can support more than one print device Print drivers

Print spooler


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Setting Up Printers

PnP devices usually works after plugging them in If necessary, can use applets to install

Open the Printers applet

Windows XP: StartPrinters and Faxes

Windows 2000: StartSettingsPrinters

Or find applet in Control Panel

Click the Add Printer icon to start the Add Printer

Wizard


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Setting Up Printers

Add Printer wizard Select local or network printer

Select a printer port


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Setting Up PrintersAdd Printer Wizard

Add the driver

Windows Update easiest to use (if driver installed)

Or can download driver from manufacturer or use CD

accompanying printer and use Have Disk

Checkmark indicates default printer

P f


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Performance

Printout may not match screen colors Monitors use RGB

Printers use CMYK

Both dont always match exactly

Calibration

Manually calibrate monitor

Print a test image and adjust monitor to match printout

Automatically calibrate printer

Use an International Color Consortium (ICC) color profile

Instructs the printer to print colors a certain way


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Troubleshooting Printers


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General Troubleshooting Issues

Tools 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


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Job never prints Is the printer on? Connected?

Does it have paper?

Check the spooler status

Can bypass spooler if desired

Strange sizes

Points to setup error

Check the Page Setup

option in the application


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Misaligned or garbage printsA corrupted or incorrect driverreinstall

You may have asked the printer to do something

it cant do, such as printing Postscript with a PCLdriver

Consumables

Printer components should be properly disposed ofto avoid environmental hazards

Some companies buy used toner cartridges


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Other Issues

Sharing 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


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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 andsmudges on paper, and so on

Gears and pulleys should be lubricated according to themanufacturers specifications

Bad-looking text

Dirty or damaged printhead

Clean with denatured alcohol or replace

Bad-looking page

Clean the platen with denatured alcohol

Replace the ribbon


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Troubleshooting Inkjet Printers

Use the maintenance software that came with theprinter setup program

Align and clean the print heads

Ink will dry out in a short time if an inkjet printer is not usedthe

ink in the tiny nozzles of the printhead dries out

Multisheet grab

Fan the paper

Let the printer rest if youve been printing a lot

Humidity can be an issue

Clean the small tank where the printhead rests or parks

with a paper towel


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Troubleshooting Laser Printers Print a diagnostic print page as a first-step in troubleshooting

Hold down the On Line button as the printer is started as a first

step in troubleshooting

Blank paper

Out of toner Print a diagnostic page, remove the toner cartridge, and look at

the imaging drumif an image is there, the transfer corona or

high-voltage power supply is bad


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Laser Printer Maintenance

Keep 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


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Laser Printer Maintenance

Certain components should be replaced regularly

Follow manufacturers recommendations

Most manufacturers sell maintenance kits for mostof their printers

Clean or replace ozone filters regularly

Check and clean fuser assembly and heat roller


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Troubleshooting Laser Printers

Blank Paper May be out of toner

Check the imaging drum to see if image is on drum

but just not transferred to paper

Could be transfer corona or high-voltage supply

Dirty printouts

Light dusting of toner on the paper (front or back)

indicates dirty printer

Clean the printer


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Ghosting

Can be light ghosting or dark ghosting

Light ghosting explored on next slide

Dark ghosting can be from a damaged drum

replace the toner cartridge

Low temperature or low humidity can aggravateghosting problems


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Light ghosting

Caused by printing an extremely dark or

complex image

Referred to as developer starvation Lower the resolution

Use different pattern

Avoid 50% grayscale and dot-on/dot-off patterns

Change the layout so grayscale patterns do not follow

black areas

Make dark patterns lighter and light patterns darker

Print in landscape

Adjust print density and RET settings

Print a completely blank page before the next one


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Vertical white lines Clogged toner

Try shaking the toner cartridge or replacing it

Blotchy print Uneven dispersion of toner

Try shaking the toner cartridge from side to side

Make sure the printer is level

Make sure the paper is not wet in spots

Check the fusing rollers and photosensitive drum for

foreign objects


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Spotty print Try wiping off the fuser rollers

Check the drum for damage

Embossed effect

Like putting a penny under a piece of paper and

rubbing it with a lead pencil

A foreign object on a roller

A foreign object on the photosensitive drum

Replace the toner cartridge


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Incomplete characters These may occur on transparencies

Try adjusting the print density

Creased pages Cotton bond paper is more susceptible

Try using a different paper type


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Paper jams Do not pull on the paper to remove it

Can damage the printer by pulling jammed paper out

Check manufacturer's jam removal procedure

If there is no jammed paper, sensors may be bad

Pulling multiple sheets

Try using a different ream of paperif that works,

the issue is humidity

Check the separation pada small piece of rubber

or cork that separates the sheets as they are pulled

from the paper tray


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Warped, overprinted, or poorly formed characters Paper that is too rough or too smooth

Dont open a ream of paper until it is loaded into the

printer

Always fan the paper before loading it in the printer Do a printer self-test to determine if it is the printer

or the computer

Replace the toner cartridge, check the cabling,

replace the data cable Turn off advanced functions and high-speed

settings to see if they may not be supported by your

software configuration


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Beyond A+DOT4

Also 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


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meljun cortes computer organization lecture chapter20

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