hardware fundamentals week 7 – lesson 1 24/05/2015hardware fundamentals1

Hardware Fundamentals

Week 7 – Lesson 1

18/04/23 Hardware Fundamentals 1

Learning Outcomes Define Visual Display Unit (VDU) characteristics: Pixel, Resolution,

Screen size and Refresh Rate Describe briefly the purpose of video standards. Discuss different video standards and high-definition television standards Define Cathode Ray Tube (CRT) characteristics: Dot pitch, Black and

White versus Colour monitors, Two types of pixel shapes, Interlaced, Non-interlaced and Radiation

Describe CRT operation, LCD operation, and Plasma operation Define Liquid Crystal Display (LCD) characteristics: Matrix, Passive

matrix and Active matrix Define Plasma characteristics Compare CRT, LCD and Plasma displays Is CRT still the best for high-definition TV? Surface-conduction Electron-emitter Display (SED) for the future


Visual Display Unit (VDU) characteristics


Pixel Picture element The smallest thing that can

be turned on or off to produce an image

A dot Anything you see on a

computer screen is a combination of these dots or pixels


ResolutionTotal number of pixels displayedResolution = # pixels across * # lines

displayed


If there are 1024 pixels across and 768 lines displayed, what is the resolution?

Resolution

1024 * 768 = 786,432


Screen sizeMeasured diagonally

across the front faceMeasured in inchesViewable areas may be

less Typical sizes: (12.1”), 14”, (14.1”),

15”, (15.4”), 17”, 19”, 20”, 21”, 22”, 24”, 27”


Refresh rateHow often the screen is refreshed or

redrawnScreen needs to be refreshed regularly

as the phosphors stop glowing and the image to be displayed changes

Measured in Hertz (i.e.. Hz) per second


Video standards


Video standards Defines the resolution and colorsfor displays The standard used, will be determined by the

monitor and the video adapter card

For high-resolution displays: Quad – is a mode with four times as many pixels

(twice the width and twice the height) Hex – is a mode with 16 times as many pixels (four

times the width and four times the height)


Video standardsName Resolution Total pixelsColour Graphics Adapter (CGA) 320 x 200 64,000

Enhanced Graphics Adapter (EGA)

640 x 350 224,000

Video Graphics Array (VGA) 640 x 480 307,200

Super VGA (SVGA) 800 x 600 480,000

eXtended Graphics Array (XGA)

1024 x 768 786,432

Super XGA (SXGA) 1280 x 1024 1,310,720

Ultra XGA (UXGA) 1600 x 1200 1,920,000

Quad XGA (QXGA) 2048 x 1536 3,145,728

Quad SXGA (QSXGA) 2560 x 2048 5,242,880

Quad Ultra XGA (QUXGA) 3200 x 2400 7,680,000

Hex Super XGA (HSXGA) 5120 X 4096 20,971,520

Hex Ultra XGA (HUXGA) 6400 X 4800 30,720,00018/04/23 Hardware Fundamentals 11

High Definition Television standards

Name Resolution Total pixels

Wide Quarter VGA (WQVGA)

400 x 240 96,000

Wide VGA (WVGA) 852 x 480 408,960

Wide XGA (WXGA) 1366 x 768 1,049,088

Wide Super XGA (WSXGA) 1600 x 1024 1,638,400

Wide Ultra XGA (WUXGA) 1920 x 1200 2,304,000

Wide Quad XGA (WQXGA) 2560 x 1600 4,096,000

Wide Quad Super XGA (WQSXGA)

3200 X 2048 6,553,600

Wide Quad Ultra XGA (WQUXGA)

3840 X 2400 9,216,000

Wide Hex Super XGA (WHSXGA)

6400 X 4096 26,214,400

Wide Hex Ultra XGA (WHUXGA)

7680 X 4800 36,864,000


Three types of monitorsCathode Ray Tube (CRT)Liquid Crystal Display (LCD)Plasma


Three types of monitors


CRT characteristics and operation


Dot pitchSpacing between each pixelTypically 0.24mm


Black and White versus Color monitors

Black and White monitor Use white pixels Made up of one phosphor

Colour monitor Uses three primary colours: Red; Green; and Blue

(RGB) Made up of three phosphors, so close that the

human eye sees the image as one single pixel


Two types of pixel shapes Triad

Three electron guns arranged with overlapping circles in a triangle

Circular holes in shadow mask Used in smaller screens (e.g. monitors)

Trinitron Three electron guns arranged in one line Three parallel slots Oval slots in shadow mask Used in large screens (e.g. televisions)


Interlaced Image on screen is created

in two halves First the odd numbered lines

then the even numbered lines

Cheaper Produce a flickering image

and jerky video motion Mostly found on older PC

monitors


Non-interlaced

Entire screen is created in one goLess flickerSmoother video motionMore commonly found


CRT operation (1 of 2) Electron gun generates an electron beam The yoke is an electromagnet. Varying the

magnetism in the yoke causes the electron beam to focus in particular areas of the screen

The shadow mask is a metal screen with holes in it. The metal blocks the electron beam but the holes will let the electron beam through when it will strike a pixel, and only one pixel. Makes sure the image is sharp

The phosphor screen is made up of the phosphors that glow when hit by the electron beam. An image is formed by turning on some phosphors but not others.


CRT operation (2 of 2) The electron beam sweeps over the phosphor

screen, making some phosphors glow, so fast that the user sees a stable image on the screen.

Other components such as the panel glass, funnel glass and the inner magnetic shield provide the structure of the CRT


Radiation

Whenever an electric current passes through a conductor (such as a wire or a copper track on a circuit board) it gives off an electro magnetic field

The electron gun, electromagnet and coil inside a CRT monitor produce magnetic fields that radiate from the monitor

Most of this radiation is exposed from the rear of the monitor


LCD characteristics and operation


MatrixA two dimensional array; that is, an

array of rows and columnsThe background area of colour display


Two methods are used to apply charges to liquid crystal cells

Passive MatrixActive Matrix


Passive Matrix Thin Film Transistor (TFT) for each row and

column Cheaper Use relatively few electrodes arranged along

the edges of the liquid crystal layer and rely on timing to be sure the correct cells are charged

The charges in the cells fade quickly, causing a faded look


Active Matrix Individual TFT’s for each cell/sub pixel (i.e.

RGB) Brighter Wider viewing angle Expensive 70% failure rate at manufacturing stage Provide a more precise and stronger charge,

creating more vivid colours


LCD operation (1 of 2) Light emanating from a fluorescent panel behind a

computers display panel spreads out in waves that vibrate in all directions

A polarising filter in front of the light panel lets through only the light waves that are vibrating more or less horizontally

In a layer of liquid crystal cells – there is one for each colour (RGB)

The light emerging from each liquid crystal cell passes through one of the three colour filters – RGB – that are arranged close to each other


LCD operation (2 of 2) The coloured beams of light pass through a second

polarising filter that is aligned to let pass only those light waves that are vibrating more or less vertically

The light that passed through a liquid crystal to which a full electrical charge was applied is now oriented perfectly to pass through the second filter.

Any light that was not twisted at all when passed through the liquid crystals is now blocked completely


Plasma characteristics and operation


Plasma characteristics Thin display, less than 2 inches thick Flat display Can be hang on the wall like a painting Plasma display is brighter than LCD Wider viewing angle than LCD (160 degrees) Larger sizes than LCD More expensive than LCD


Plasma operation (1 of 3) Two sets of electrodes

Address Electrodes are positioned vertically in the rear of the display

Display Electrodes are positioned horizontally in the front of the pixels

These electrodes run through layers of glass and magnesium oxide, which protect and insulate the electrodes from each other

Pixels are called cells, these are depressed in ridges called ribs

The ribs separate the cells Trapped inside each cell is a mixture of xenon and

neon gases


Plasma operation (2 of 3)

Illuminate tiny coloured fluorescent lights to form an image

Each pixel is made up of three fluorescent lights: a red light; a green light; and a blue light

Display varies the intensities of the different lights to produce a full range of colours

The central element in a fluorescent light is a plasma, a gas make up of free-flowing ions (electrically charge atoms) and electrons (negatively charged particles)


Plasma operation (3 of 3) When an electrical current runs through a plasma,

negatively charged particles are rushing toward the positively charged areas of the plasma, and the positively charged particles are rushing toward the negatively charged areas

In this mad rush, particles are constantly bumping into each other

These collisions excite the gas atoms in the plasma, causing the plasma screens to release light photons of energy


CRT versus LCD versus Plasma



Calculated longer lifeHigher refresh rate

Not affected by magnetic fieldsWider viewing angle

No radiationMore contrast

LighterBrighter colours

Flat more compact screenMore robust

Uses less powerCheaper

LCDCRT

LCD Plasma

Cheaper More expensive

Positioned on desk Hang on the wall

Best image front-on Wider viewing angle

Smaller sizes Larger sizes

Brighter display


Is CRT still the best for high-definition TV?


CRT monitor Despite the popularity of LCD and Plasma

screens, the best display of high-definition TV is still the CRT monitor


SED for the future


Surface-conduction Electron-emitter Display (SED) Developers are Canon and Toshiba Combines the best of CRT’s, LCD’s and plasma

displays Will have the visual quality of a CRT monitor and the

slimness of LCD and plasma flat panels Requires less materials than LCD and less expensive

circuitry than plasma Screen is made up of phosphors (CRT) painted on the

inside of a plate of glass, each phosphor dot has its own emitter which shoots electrons at only its matching phosphor (no electron beam)


References Required textbook http://www.howstuffworks.com http://www.webopedia.com http://www.fourmilab.ch/documents/howmanydots/


hardware fundamentals week 7 – lesson 1 24/05/2015hardware fundamentals1

Documents

wide xga wxga1366 x

quad xga qxga2048 x

super xga sxga1280 x

wide quad xga wqxga2560

ultra xga uxga1600 x

wide super xga wsxga1600

wide ultra xga wuxga1920

hardware fundamentals3