CC - Lecture 3

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Lecture 3 Seeing, Hearing, and Printing DataComputer Concepts

Monday, September 29, 2008

Course Instructor :

BE [CE], MS[CS] National University FAST

Email : [email protected]

INSTITUE OF BUSINESS MANAGEMENT - IoBM

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

MonochromeOne color with black background

GrayscaleVarying degrees of gray

INSTITUE OF BUSINESS MANAGEMENT IoBM

ColorDisplay 4 to 16 million colors

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Monitors Cathode Ray Tube (CRT)

A standard monitor screenis a CRT (cathode ray tube).

The screen is coated on theinside surface with dots of chemicals called phosphors.


en a eam o e ectronshits a dot, the dot willglow.

Monitors CRT color

On a color monitor these phosphor dots are in groups of three: Red, Green, and Blue.

This RGB system can create all the other colors by combiningwhat dots are aglow.

There are 3 signals that control the 3 electron beams in themonitor, one for each RGB color.

Each beam only touches the dots that the signal tells it to


.

All the glowing dots together make the picture that you see.The human eye blends the dots to "see" all the differentcolors.

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Monitors CRT drawbacks

Ver lar e Very heavy Use a lot of electricity


Monitors Liquid Crystal Display

LCD Commonly found on

laptops Desktop versions exist Solve the problems of

CRT Fluorescent li hts


provide illumination

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Monitors

Passive matrix LCD xe s arrange n a gr

Pixels are activated indirectlyRow and column are activated

Animation can be blurry


Monitors Active matrix LCD

ac p xe s act vate rect y Pixels have 4 transistors

One each for red, green, blueOne for opaqueness

Transistors arranged in a thin film


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Monitors

Drawbacks to LCD More expensive than CRT Must sit directly in front of screen Can be more fragile than CRT


Monitors Paper-white displays

Electro-luminescent displays (ELD)

Similar to LCD Uses phosphor to produce light

Plasma monitor Gas is excited to roduce li ht


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Monitors & Video Cards

Monitors impacts user effectiveness Monitors should have

Crisp text Clear graphics Adjustable controls Clear edges


Monitors & Video Cards Size of monitor

Measured in inches Measured diagonally Actual size

Distance from corner to corner Viewable size

Useable portion of the screen


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Resolution Number of pixels on the

screen Higher number creates

sharper images Higher number creates



Dot pitch Distance between the same

color dots Ranges between .15 mm and

.40 mm Smaller creates a finer


Should be less than .22

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Video Cards

Device between the CPU and monitor Better cards result in better output

Removes burden of drawing from CPU Have their own processor and RAM Modern cards have up to 512 MB RAM Capable of rendering 3D images


Ergonomics and Monitors Eyestrain

at gue o t e eyes Steps to avoid

Choose a good monitorPlace the monitor 2 3 feetawayCenter of screen below eye level


Avoid reflected light

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Ergonomics and Monitors Electronic magnetic fields

Generated by all electronicdevices

EMF may be detrimental tohealth

Steps to avoid


length

Take frequent breaksUse an LCD monitor

Data Projectors Replaced overhead and slide projectors

ro ec ma e on o wa or screen LCD projectors

Most common type of projector Small LCD screen Very bright light


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Data Projectors

Digital Light Projectors ser es o m rrors contro t e sp ay

May be used in a lighted room


Sound Systems Integral part of the computer experience

Capa e o recor ing an p ay ac


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Sound Systems Sound card

Device between the CPU andspeakers

Converts digital sounds toanalog

Can be connected to severaldevices


o ern car s suppor o ySurround Sound

Sound Systems Headphones and headsets

Re lacement for s eakers andmicrophones

Offer privacy Does not annoy other people Outside noise is not a factor Headsets have speakers and a


m crop one

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Commonly Used Printers Impact printers

Generate out ut b strikin the a er Uses an inked ribbon

Non-impact printers Use methods other than force Tend to be quiet and fast


Commonly Used Printers Dot matrix printers

Im act rinter Used to print to multi-sheet

pages Print head strikes inked ribbon Line printers Band printers


Speed measured in characters per second

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Dot Matrix Print Head


Commonly Used Printers Ink-jet printers

- Inexpensive home printer Color output common using CMYK

Cyan, magenta, yellow, black Sprays ink onto paper S eed measured in a es er minute


Quality expressed as dots per inch

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Dots Per Inch


Commonly Used Printers Laser printer

- Produces high quality documents Color or black and white Print process

Laser draws text on pageToner sticks to text


Toner melted to page Speed measured in pages per minute Quality expressed as dots per inch

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Comparing Printers

Determine what you need Determine what you can spend

Initial cost Cost of operating Image quality Speed


Commonly Used Printers All-in-one peripherals

, , Popular in home offices Prices are very reasonable


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High-Quality Printers Special purpose printers

Output is professional grade Prints to a variety of surfaces


High-Quality Printers Photo printers

Produces film quality pictures Prints very slow Prints a variety of sizes


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High-Quality Printers

Thermal wax printers ro uces o co or output

Color generated by meltingwax

Colors do not bleed Operation costs are low



D e sublimation rinters Produces realistic output Very high quality Color is produced by

evaporating ink Operation costs are high


Output is very slow

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Plotters Large high quality blueprints Older models draw with pens Operational costs are low Output is very slow


CC - Lecture 3

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