Peter Norton, 6th edition

By: Rena Essa

Lesson 4A: Video and Sound

Most common output device Connects to the video card Categorized by color output:

Monochrome One color with black background

Grayscale Varying degrees of gray

Color Display 4 to 16 million colors

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1.Cathode Ray Tube (CRT)Most common type of monitorElectrons fired from the backElectrons excite phosphor to glowPhosphor is arranged in dots called pixelsDot mask ensures proper pixel is lit

2. Cathode Ray Tube (CRT)Phosphor dots arranged in griadsRed, green, and blue dots

Three colors blend to make colors Varying the intensity creates new colors

CRT drawbacksVery large Very heavyUse a lot of electricity

3. Liquid Crystal Display (LCD)Commonly found on laptopsDesktop versions existSolve the problems of CRTFluorescent lights provide illumination

2 types of LCD Monitors: 1.Passive matrix LCD

Pixels arranged in a grid Pixels are activated indirectly Row and column are activated Animation can be blurry

2 types of LCD Monitors: 2. Active matrix LCD

Each pixel is activated directly Pixels have 4 transistors One each for red, green, blue One for opaqueness Transistors arranged in a thin film Animation is crisp and clean

Drawbacks to LCDMore expensive than CRTMust sit directly in front of screenCan be more fragile than CRT

4. Paper-white displaysHigh contrast between the monitor’s white

background and displayed text or graphics.

5. Electro-luminescent displays (ELD)Similar to LCDUses phosphor to produce light

6. Plasma monitorGas (neon or xenon) is excited to produce

light

Monitors impacts user effectiveness Monitors should have

Crisp textClear graphicsAdjustable controlsClear edges

Monitors Specification:1. Size of monitor

Measured in inchesMeasured diagonallyActual size

Distance from corner to cornerViewable size

Useable portion of the screen

2. ResolutionNumber of pixels on the screenHigher number creates sharper imagesHigher number creates smaller images

3. Refresh rateNumber of time the screen is redrawn Improper settings can cause eyestrain

4. Dot pitchDistance between the same color dotsRanges between 0.15 mm and 0.40 mmSmaller creates a finer pictureShould be less than 0.22

Device between the CPU and monitor Better cards result in better output Removes burden of drawing from CPU Have:

processor RAM

Modern cards have up to 512 MB RAM

Capable of expose 3D images Controls how things look on-screen

Eyestrainweakness of the eyesSteps to avoid

Choose a good monitor Place the monitor 2 – 3 feet away Center of screen below eye level Avoid reflected light

Electronic magnetic fields (EMF)Generated by all electronic devicesEMF may be harmful to healthSteps to avoid

Keep the computer at arms length Take frequent breaks Use an LCD monitor

Replaced overhead and slide projectors Project image onto wall or screen Two types:

LCDDLP

Two types:1.LCD projectors

Most common type of projector Small LCD screen Very bright light Require a darkened room

2. Digital Light Projectors (DLP) A series of mirrors control the display May be used in a lighted room

Integral part of the computer experience

Capable of recording and playback Sound card

Device between the CPU and speakersConverts digital sounds to analogCan be connected to several devicesModern cards support Dolby Surround

Sound

Headphones and headsetsReplacement for speakers and microphonesOffer privacyDoes not annoy other peopleOutside noise is not a factorHeadsets have speakers and a microphone

Chapter 4seeing ,Hearing and printing data

Lesson 4B:Printing

Impact printersGenerate output by striking the paperUses an inked ribbon

Non-impact printersUse methods other than forceTend to be quiet and fast

Impact printer: Dot matrix printers

Impact printer Used to print to multi-sheet pages Print head strikes inked ribbon Speed measured in characters per second. Two Types:

Line printersBand printers

Non impact printers:1. Ink-jet printers

Non-impact printer Inexpensive home printer Color output common using CMYK Cyan, Magenta, Yellow, Black Cyan : blue, Magenta :ارجواني Sprays ink onto paper. Speed measured in pages per minute. Quality expressed as dots per inch.

2. Laser printer Produces high quality documents Color or black and white Print process

Laser draws text on pageToner sticks to textToner melted to page

Speed measured in pages per minute Quality expressed as dots per inch

3. All-in-one peripherals Scanner, copier, printer and fax Popular in home offices Prices are very reasonable

Determine what you need Determine what you can spend Initial cost Cost of operating Image quality Speed

Special purpose printersUsed by a print shopOutput is professional gradePrints to a variety of surfaces

Photo printersProduces film quality picturesPrints very slowPrints a variety of sizes

Thermal wax printersProduces bold color outputColor generated by melting waxColors do not bleed Operation costs are lowOutput is slow

Dye sublimation printersProduces sharp imagesVery high qualityColor is produced by evaporating inkOperation costs are highOutput is very slow

PlottersLarge high quality blueprintsOlder models draw with pensOperational costs are lowOutput is very slow