Chap1.5 Input Devices

8/12/2019 Chap1.5 Input Devices

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The followin! are five simple techniBues which are used to carr$ out various

operations

% point ; means to move the mouse to the correct position' clic& ; to clic& means to press and release the left mouse #utton once It

allows the section of the menu item represented #$ the icon which is

currentl$ #ein! pointed to #$ the !raphics cursor The ri!ht cursor is usedto call up a menu options

( dou#le clic& ; means to press and release the left #utton twice inn rapid

succession It allows e>ecution of the pro!ram represented #$ the icon"which is currentl$ #ein! pointed to #$ the !raphics user

) simultaneous clic& ; means to press and release #oth the left and ri!ht

mouse to!ether The actual functionalit$ for simultaneous varies from

software pac&a!e to pac&a!e

+ dra! ; To dra! means to position the !raphics cursor over the !iven item"then depress the #utton and hold it down as the cursor is moved on the

screen 6ou ma$ dra! a icon to chan!e its location on the screen To draw!raphics o#*ects such as line" circles" curves etc

97: T/AC57A

It is similar to a mouse #ut its #all that is at the #ase of a mouse is place on the top

alon! with the #uttons in case of a tacall To move the !raphics cursor around thescreen "the #all is rolled with the fin!ers The whole device is not moved for movin! the

cursor hence the tracall reBuires less space than a mouse for the operation Thetracall #uilt in the &e$#oard are commonl$ used in APTPS The three commonl$used shapes for the #all are #utton" #all or a sBuare


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9C: 6STIC5

It is pointin! device that wor&s on the similar principle as the tracall To ma&e the

movement the spherical #all eas$" the spherical #all moves in a soc&et with a stic&

mounted on it The stic& can #e moved forward or #ac&wards " left or ri!ht and to theposition the cursor at the desired position The #utton on top is provided to select the

option" which is currentl$ pointed to #$ the cursor The #utton is clic&ed ot ma&e this

selection

DATA SCANNIN@ DEVICE

In order to reduce the possi#ilit$ of human error in data entr$" the data can #e entered

directl$ from the source document Data scannin! devices are input devices used fordirect data entr$ into the computer s$stem from source documents

=ith Data scannin! device followin! points to #e &ept in mind8

Eliminate some of the duplication of human efforts to !et the data in the computer

Improves data accurac$

The$ demand hi!h Bualit$ of input document

orm desi!n and in& specification #ecomes more critical


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9A: SCANNE/ 8 is an input device that translated paper documents into an electronic

format that can #e stored in a computer The input document ma$#e a t$ped te>t"

pictures" !raphics or even handwritten documentsIma!e scanners are also called optical scanners #ecause the$ use optical

technolo!$ for convertin! an ima!e into electronic form An intersection of a

hori2ontal and a vertical line of !raph is called the !rid point If there is a dar&point on the !rid point it is a % otherwise it is a 4 This is called a #it map

representation Each #it is the representation of the ima!e is called a pi>el

Ima!e scanner are of two t$pes8

9%: Flat bed scanner - it is li&e a cop$ machine consistin! of a #o>

havin! a !lass plate in its top and a lid that covers the !lassplate The document to #e scanned is place upside down on the

!lass plate

9': Hand held scanner8 has a set of li!ht emittin! diodes encased

in a small case that can #e convenientl$ held in hand durin!operation To scan a document the scanner is slowl$ dra!!ed

ver$ steadil$ and carefull$ over the document" therefore hand

held scanner are used onl$ in cases where hi!h accurac$ is notneeded


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97: ./ 9optical mar& reader: ; these scanners are capa#le to reco!ini2in! a pre-specified t$pe of mar& made #$ pencil or pen E>ample 8 man$ students mi!ht have

appeared in o#*ective t$pe tests where the$ had to mar& their answers to Buestions #$

a pencil to indicate their correct choice The answer sheets are directl$ fed to acomputer for !radin! with the use of an optical mar& reader

The actual techniBue used #$ an ./ device for reco!nition of mar&s involvesfocusin! a li!ht on the pa!e #ein! scanned and detectin! the reflected li!ht pattern

from the mar&s ./ needs

Pre printed forms need a !ood Bualit$ paper

7o>es to #e mar&ed in them accuratel$

The form should not #e folded

9C : 7A/ CDE /EADE/

Data is coded in the form of small lines 9&now as #ars: are &now as #ar codes 7ar codes

represents alphanumeric data #$ a com#ination of ad*acent vertical lines 9#ars: #$


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var$in! their width and spacin! #etween them A #ar code is reader is a device used for

readin!9decodin!: #ar coded data It ma$ #e hand held scanner or ma$ #e em#edded in a

stationar$ scanner It scans a #ar code ima!e and converts it into a an alphanumericvalue" which is then fed to the computer to which the #ar code reader is connected " *ust

as thou!h the alphanumeric value had #een t$ped on a &e$#oard

A #ar code reader uses a laser #eam scannin! technolo!$ The laser #eam is stro&edacross the patterns of #ars of a #ar code i!ht patterns are converted into electrical

pulses and then transmitted to reco!nition lo!ic circuits which converts it into an

alphanumeric value

7ar code readers are commonl$ found in supermar&ets and department stores

9D: .IC/ ;9ma!netic in& character reco!inition:

It is similar to C/ and is used #$ the #an&in! industr$ for faster processin! of thelar!e volume of cheBues #ein! handled ever$da$ 7an&s that emplo$ .IC/

technolo!$ use a special t$pe of cheBue The #an& identification code 9name " #ranch

etc: " account num#er" and the cheBue num#er are pre-printed 9encoded: usin!characters from a special character set on all these chec&s with a special in& that

contains ma!neti2a#le particles of iron o>ide #efore the cheBues are issued to the

customer


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9E: DI@ITIFE/

A di!iti2er is an input device used for convertin! 9di!iti2in!: pictures" maps"

Drawin! into di!ital form for stora!e in computers A di!iti2er consists of di!iti2in!

ta#let 9also &now as !raphics ta#let: associated with a st$lus The di!iti2in! ta#let is a flat

surface that contains hundreds of fine copper wire formin! a !rid Each copper wirereceives electric pulses The st$lus is li&e a pen or lens li&e cursor which converts the

pictures into the di!ital form Di!iti2ers are commonl$ used in the area of CAD

9computer aided desi!n: #$ the architects and en!ineers to desi!n cars"#uildin!s ro#ots

9: EECT/NIC CA/D /EADE/

The$ are small plastic cards havin! encoded data appropriate for the application for

which the$ are used An electronic card reader is connected to the computer which is

used to read the data encoded in the an electronic card and transfer it to the computerfor further processin!

Electronic cards are often used #$ #an&s and issued to customers for use in

AT. 9automatic teller machine: An AT. allows a customer to depositor withdraw cash ') hours a da$ without needin! to interact with the #an&

Electronic cards are also used #$ man$ ori!ani2ations for controllin!

access to ph$sicall$ secured area

The$ are of two t$pe

% ma!netic strip cards8 the$ have a ma!netic strip on their #ac&The data to #e encoded on the card is stored on the ma!netic

strip


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' smart card8 have #uilt in microprocessor chip instead f a

ma!netic strip" the data encoded on the card in permanentl$

stored in the memor$ of the microprocessor

9@: VICE /EC@INITIN DEVICE

The$ allow the person to input data to the computer s$stem #$ spea&in! to itThe$ have limited success #ecause the correct interpretation #$ the machine

of a lar!e num#er of words in a voca#ular$ of a lan!ua!e is difficult The

ma*or difficult$ has #een that people spea& with different accent and tones

It consists of an input device such as a telephone or a microphone that

converts human speech into electric si!nals

A si!nal pattern is sent to the computer where it is matched a!ainst the

pre-stored patterns to identif$ the input

=hen a close match is found" a word is reco!ni2ed #$ the s$stem

The set of pre-stored patterns is &now as the voca#ular$ of the s$stem
http://commons.wikimedia.org/wiki/Image:Credit-cards.jpg


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9?: =E7 CA.E/A

A we# camera allow a computer to accept input *ust #$ focusin! on a o#*ect #$ ta&in!

its picture Picture so ta&en can #e transferred over the networ& to a distant placeIt creates an ima!e of an o#*ect in di!ital form9in %s and 4s: so that it can stored and

interpreted #$ the computer

9 :VIDE CA.E/A

A video camera ta&es continuous pictures and !enerates a di!italGanalo! si!nalsfor displa$ on a monitor or permanent recordin! A video camera captures ima!es

#$ #rea&in! down the ima!es into series of lines Each line is scanned one at a

time and continuousl$ var$in! intensities of redG!reen and #lue li!ht are filteredand converted into analo! si!nals These are then used to send picture over a

networ& throu!h computers

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http://en.wikipedia.org/wiki/File:Betacam_SP_camera.jpghttp://szwelldytech.en.made-in-china.com/product/WoAxDJcUalhd/China-PC-Camera-WD-W040-.html


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Chap1.5 Input Devices