Input Devices as Lvl

8/8/2019 Input Devices as Lvl

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INPUT DEVICESINPUT DEVICESINPUT DEVICESINPUT DEVICES


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INPUT DEVICES Input devices send signals and

commands to computer.

1) Keyboard: is the most commonlyused input device.


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Types of keyboard 1) QWERTY KEYBOARD: is the most

common type of keyboard. Its name

comes from the first row of letterson the keyboard.


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Using a keyboard for too long can lead

to health problems such as repetitivestrain injury (RSI). To try toovercome this, different styles ofkeyboard have been developed, for

example, the ergonomic keyboard.They are supposed to put your handsinto a much more natural position

than a traditional keyboard.


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2) Concept Keyboard

A concept keyboard is a flat boardthat contains a grid of buttons. Eachbutton can be programmed to dowhatever you want.


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Concept keyboards are used when fast

input is needed and they are ideallysuited to selecting from a limited rangeof choices such as fast foodrestaurants. Checkout tills such as

McDonalds use symbols to makeordering faster and easier.


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Primary schools often use them with young

children. The overlay image could be apicture of a farmyard. Pressing on ananimal would cause the computer to makethe right animal noise.

Concept keyboards are particularly usefulfor people who would find using anordinary keyboard difficult. It is also very

handy in locations where an ordinarykeyboard might be damaged (e.g. by dust)


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2) POINTING DEVICESAll pointing devices are input devices.

Here are types of pointing devices:

a) The mouse: is also called a pointingdevice because it enables you tocontrol what happens on the screen bymoving the mouse for pointing ,clicking

and selecting items on the screen .


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b)A Joystick:

Joysticks were originally used by pilotsas part of an aeroplane's controls andthe technology was developed to letcomputer gamers experience a morerealistic game environment.

You can move joysticks in manydirections and the joystick tells the

computer which direction it has beenmoved into..


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They also have one or more buttonswhose position when pushed can be

read by the computer.

Joysticks can also be used for

controlling machines such as cranes,trucks and powered wheelchairs


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Advantages of Using Joystick :

1) They give a better gaming experiencefor racing or flying styles of computergames.

Disadvantages :

1) Some people find joysticks moredifficult to control than to atraditional mouse.

2) Joysticks are not particularly robustand can break easily if too much forceis used on them.


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c) A tracker ball

It is like an upside- down mouse. Theball is on top of the device and youmove it with your thumb.


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d)A Track PointIt is a small round-shapedcap in the

middle of the keyboard, like the pencileraser.


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e) A trackpad /TouchpadIt is a small,flat, square pad below the

spacebar.


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f)Graphic tablet/graphicpad

Graphics tablets are often usedby graphics designers and

illustrators. Using a graphics tablet, a

designer can produce much more

accurate drawings on the screenthan they could with a mouse orother pointing device.


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Drawings created using a graphicstablet can be accurate to withinhundredths of an inch.

a graphics tablet consists of a flatpad (the tablet) on which you drawwith a special pen. As you draw onthe pad, the image is created onthe screen.

The graphic tablet is used mainly forcomputer aided designs.


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3) SCANNERS

Scanners can be used to convert imagesor text on paper into a digital formatthat can be used by computer.


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There are 2 types of scanners:

1) flatbed scanners

2) Hand-held scanners


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Advantages Any image which is digitised by the scanner

can then be included on electronicdocuments Images once digitised can be enhanced with

a graphics application

Disadvantages Images can take up a lot of memory space Images lose some quality in the scanning and

digitising process The quality of the final image is dependent

on the quality of the original image


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4) DIGITAL CAMERA

It stores and sends picturesdigitally with computers.

Advantage:

Photographic film is not needed.It can easily send by e-mail.

Unwanted images can be deleted

straight awayDisadvantage:

It may need lots of memory.


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5)MICROPHONE

A microphone is used to input sounds tocomputer.


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6) Magnetic InkCharacter Recognition

Each day, banks process millions ofcheques. It would take them far too

long to manually enter the data fromeach cheque. They use a techniquecalled 'Magnetic Ink CharacterRecognition' (MICR) which enablesthem to process 300 cheques perminute with 100% accuracy.


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At the bottom of each cheque are aseries of numbers which record:

* the cheque number * the bank or building society sort code

* the customer's account number

These numbers are written in aspecial ink which contains ironparticles. This ink is magnetised and

commonly called 'magnetic ink'. It canbe read by a special machine called aMagnetic Ink Character reader

(MICR).


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The MICR will only recognise numbersprinted in a standard font using the

magnetic ink. This provides a high levelof security because any attempt toalter the magnetic ink printout with

normal ink by writing over it will beignored.

Both the Reader and the magnetic inkare expensive and so are generally onlyused by banks.


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7) Optical Mark Reader(OMR)

Have you ever looked closely at theNational Lottery ticket selectionform? Or have you ever had to do a

multiple choice test at school whereyou had to use a pencil to show youranswer (like our picture below)?


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Most forms are scanned by a specialpiece of equipment called an 'Optical

Mark Reader' (OMR). They detect thepresence of your pencil mark byreflecting light onto it. Less light isreflected where a mark has been made.

The OMR then interprets the pattern ofmarks and sends the results to thecomputer for storage, analysis and

reporting.


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Advantages :

A fast method of inputting largeamounts of data - up to 10,000 formscan be read per hour depending on the

quality of the machine used. Only one computer needed to collectand process the data

OMR is much more accurate than databeing keyed in by a person


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Disadvantages : If the marks don't fill the space completely, or

aren't in a dark enough pencil, they may not beread correctly

Only suitable for recording one out of a

selection of answers, not suitable for text input

The OMR reader needs the answers to be on the

prepared forms which will all be identical to oneanother. You can't just pick up a blank sheet ofpaper and mark your answers on it.


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8) Optical Character

Recognition (OCR)An OCR system consists of anormal scanner and some special

software. The scanner is used toscan text on a document or pieceof paper into the computer. TheOCR software then examines the

page and changes the letters intoa form that can be edited orprocessed by a normal word

processing package.


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*The ability to scan the charactersaccurately depends on how clear the

writing is.*Scanners have been improved to be

able to read different styles and sizes

of text as well as neat handwriting.*Although they are often up to 95%

accurate, any text scanned with OCR

needs careful checking because someletters can be misread.


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Advantages Cheaper than paying someone to

manually enter large amounts of text.

Much faster than someone manuallyentering large amounts of text .

The latest software can recreatetables and the original layout


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Disadvantages : Not 100% accurate, there are likely to be

some mistakes made during the process

All documents need to be checked overcarefully and then manually corrected

If the original document is of poor quality

or the handwriting difficult to read, moremistakes will occur

Not worth doing for small amounts of text


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9 ) Touch Screen

A touch screen is the only devicewhich works as both an input and an

output device. You view the optionsavailable to you on the screen

(output) and you then use your

finger to touch the option that you

have chosen (input).


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*Touch screens are easy to use and areoften found in public places such as

cashpoints at banks, ticket collectionterminals (at theatres or airports),information centres (at museums.)

*Touch screens are not commonly usedto input large amounts of databecause they are not very accurateand they would be tiring on the handsto use for long periods of time.


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10) Magnetic Stripe

Reader Magnetic strips are usually found ofthe back of most credit cards,cheque guarantee cards, loyalty

cards, membership cards etc.


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The magnetic strip can hold personaldetails about the card number such as

account number and name. The stripcan contain up to 60 characters,stored magnetically.

To read the data on the card, it is'swiped' through a Magnetic StripeReader machine and the data is readand fed back to the computer.


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11) Smart Cards Smart cards are often called input

devices. In fact they are actuallysimple storage devices. A smartcard contains a small RAM chip.

When the card is put into amachine data can be read from thecard or written onto it. A smartcard can store much more data

than a magnetic stripe can. Apopular card in use at the momentcan store 8k (about 8000

characters) of information.


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12)Barcode readers Barcode readers are classed asautomatic input devices.

Most items that are for sale in shopshave a barcode printed somewhere onthe packaging.


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The barcode is a series of verticalbars of varying widths that give

information about: the country of manufacture

the name of the manufacturer

a product code


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A barcode reader is an automatic inputdevice which is used to scan or 'read'

the barcode by using a visible redlight. The reflected light is translatedinto digital data that is interpreted by

the computer to identify the productand price from the database.


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13) Webcam

A webcam is an input device becauseit captures a video image of thescene in front of it.

It is either built in to the computer(e.g. laptop) or it is connectedthrough an USB cable.


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Common uses of webcams include:

Chatting

Webcams are commonly used to allowpeople to see each other whilstchatting over the internet. Formallythis is called 'teleconferencing'

Security

Webcams can also be used to caputure

an image only if movement is detectedin the scene in front of it so they arewidely used in burglar alarm and othersecurity equipment


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Tourists

There are hundreds of webcamsdotted around the world that arepointed to an interesting scene suchas the outside view of a lab in the

Arctic or maybe the Niagra Falls. Theweb cam is attached to a computerwhich sends an image to a server on

the internet on a regular basis. Peoplethen connect to the server to see thelatest image.


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14 ) Remote Control A remote control is a hand-held device

which is used to control a machine froma short distance away. Remote controlsneed line-of-sight in order to sendtheir signals to the receiving device,obstacles such as furniture or walls canblock the signal.

Some remote controls allow text to betyped, for example, making a note ofthe name of a TV programme which hasbeen recorded.


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Examples of use for remote controls:

Televisions

Music systems

Lighting systems

Heating systems


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15 ) Biometric Devices There is an increasing trend towards

using biometric data from people inorder to identify them. Finger printand retinal identification are beingused in many places now and even

facial recognition systems arestarting to be introduced.

Special devices are needed tocapture the biometric data which isthen passed onto the computer forprocessing and identification.


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Biometric authentification methods

can be used to identify you at ATMsto withdraw cash, in computernetworks to allow you to log on andmany schools are now introducing

'fingerprint registration'.


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16 ) Sensors These detect changes in the physical or

chemical environment and convert theminto electrical signals. These signals canthen be digitised and used by thecomputer..


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Advantages: There are a huge rangeof possible sensors and they include:heat; light; sound; movement;magnetism; pressure; strain; acidity(pH); oxygen levels; liquid levels;

humidity; pulse rates; salinity; waterflow; speed and acceleration.

Disadvantages: Most sensors need an

interface to convert analogue signalsinto the digital signals that acomputer can understand.


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Temperature sensor : used inautomatic washing machines,automatic cookers, centralheating controllers,computer-controlled greenhouses, scientific

experiments and environmentalmonitoring.

Pressure sensor : Burglar alarms,

automatic washing machines,robotics, production linecontrol,scientific experiments andenvironmental monitoring


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Light sensor: Computer controlledgreenhouses, burglar alarm systems,robotics, production line control,scientific experiments andenvironmental monitoring


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17 ) Light PenA light pen is a special pen which you

can point at any computer monitor. Whenthe pen is pointed at the screen thecomputer can work out where the pen ispointing.

Light pens can be used to "draw" onthe screen or to select options frommenus presented on the screen. Light

pens are extremely poor input devices.They are very inaccurate and tiring touse. Light pens are hardly ever usedtoday


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It is suitable to use where desktopspace is limited, it is used instead of

a mouse or for drawing applicationswhere a graphics tablet might be toobig


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18 ) Video Digitiser It inputs a video to digital format from an

analogue source (for example television orvideo camera)

A video digitiser is used to convert

sequences of analogue images into a digitalformat. The digitised images can then besaved as a file and played back on amonitor to produce a moving image.


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Advantages:

1) Digital video is easilyedited. Sections can easily be cutand pasted together and digitaleffects added.

2) The output can be rendered into awide range of formats ranging fromDVD quality down to streaming video

suitable for the Internet.


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Disadvantages:

1)Video files take up a great deal ofmemory.

2)Fast video capture cards may be

needed to capture high quality videofootage.

3)A powerful computer and graphicscard is often needed to process videofootage.


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19 )MIDI instruments MIDI stands for Musical Instrument

Digital Interface. These are normalmusical instruments which have a MIDIport for input into a MIDI interface in

the computer. The notes are convertedinto digital data and saved as a file onthe computer. This data can beconverted back into notes or edited by

computer software. The software often has a wide range ofspecial effects or stored sound datafrom real instruments.


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Advantages:

Data from a musical instrument iseasily captured and edited with acomputer.

MIDI files are small. MIDI files can be recorded on onetype of instrument and played back onanother.


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Disadvantages:

Audio cannot be recorded directly asan audio files such as MP3.

The playback depends on the

instrument/computer sound card somay not sound the same as theoriginal.

Only the note and the timing arestored.


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INPUT DEVICES

Date post:	09-Apr-2018
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