Various Input Devices:

Input Devices:

Input devices allow users and other applications to input data into the computer for processing. The data input to a computer can be in the form of text, audio, video etc. Common input devices include keyboard, mouse, joystick, trackball, touch screen, light pen, digitizer, scanner, magnetic ink character recognition (MICR), optical mark reader (OMR), optical character reader (OCR), bar code reader, microphone and web camera.

Let us discuss the various input devices.

1. Keyboard

They allow data entry into a computer  system by pressing  a set of keys  (labeled  buttons)  neatly  mounted  on a keyboard  connected  to a computer  system.  The most popular  keyboard  used today  is the  101-keys  QWERTY  keyboard . Some keyboards have 110 keys, where the extra keys are designed to work with the Windows operating system.

The key board has five sections

i. Typing keys – 1,2,3,…..A,B,C………)

ii. Numeric keypad – numeric keys on the right side of the keyboard

iii. Function keys – F1,F2….…..on top side )

iv. Control keys – cursor keys, ctrl, alt…..)

iv. Special purpose keys – Enter, shift, spacebar….)

2. Mouse

It is the most common pointing input device. The data is entered by pointing the mouse to a location on the computer screen. The mouse may also be used to position the cursor on screen, move an object by dragging, or select an object by clicking. The key benefit of using a mouse is that the cursor moves with the mouse. So, the cursor can be positioned at any location on the screen by simply moving the mouse.

There are following three types of mouse :

i. Mechanical/Physical

Mechanical mouse has a rubber or a metal ball on its underside that can roll in all directions, Mechanical sensor detects the direction of the rolling ball and make the movement of the screen painter accordingly.

ii. Opto-mechanical mouse

It is also similar to the mechanical mouse except that it uses optical sensor to detect the movement to the ball on the mouse pad.

iii. Optical mouse

It uses a Light Emitting Diode (LED) and  sensor to detect the movement of mouse. Optical mouse requires an opaque flat surface underneath it. Optical mouse was introduced by Microsoft in 1999. Optical mouse is better than physical mouse as there is no moving part that can cause wear and tear, and dirt cannot get inside it.

3. Trackball

Trackball is a pointing device, which looks like a mouse. It is used to move the cursor and works like a mouse.It is particularly used in the notebook computer.

4. Joystick

A  joystick    is  a   pointing   device   that   works   on  the   same principle    as   a   trackball.    To   make   the   movement    of the spherical   ball  easier,   it  is  placed   in ‘a  socket   with   a  stick mounted on it. A user moves the spherical ball by  the  attached  stick   with   his/her   hand. (the    stick  can  be moved forward  or backward,  left or right, to move and position the  graphics  cursor  at the desired  position)  Potentiometers   are used  to sense  the  movements. On     most joysticks,   a button  on the top  is provided  to select the option  currently  pointed  to by the   cursor. The button is called to make   this   selection. Typical    uses   of   a   joystick    include  video games,  flight simulators,     training     simulators,     and    remote     control     of industrial robots.

5. Light Pen

It is a light sensitive pen-like input device and is used to select objects directly on the computer screen. It is used for making drawing, graphics and for menu selection. The pen contains a photocell in a small tube. When the pen is moved on the screen, light from the screen at the location of pen causes the photocell to respond. The electric response is transmitted to the computer that can identify the position on screen at which the light pen is pointing.

6. Touch Screen

Touch   screen  is the most simple,  intuitive,  and easiest  to use of all input devices.  A touch; screen enables  a user to choose  from available  options  by simply touching  the desired  icon or menu  item displayed  on a computer’s   screen with his/her finger. TOUCH screens  are  often  used  in information   kiosks.  An  information   kiosk  is an unattended   system  located  at a public  place that  stores  information  of public  interest  and allows  common  people  to access  stored  information  as per their requirement.   For example,  information  kiosks may be located:

i. At  an  airport   or  a  railway   station   to  provide   information   to  arriving   passengers   about   hotels, restaurants,  tourist  spots, etc. in a city.

ii. In large museums or zoos to guide the visitors  to the locations  of various  attractions  and facilities,  and to caution  them against  things they are not supposed  to do while

iii. In a large bank, post office, or insurance  company  to introduce  the various  types of-offered  services  to the customers,  and to guide them to appropriate  counters  for their  specific jobs.

7. Digitizer

A digitizer or a graphic tablet is similar to a light pen. It is used to create drawings and pictures. Instead of drawing on the screen, a separate tablet is used on which a special stylus is moved. The digitizer consists of three main parts-tablets, puck and stylus. Digitizers are commonly found in CAD terminals or engineering workstations.

8. Scanner

A scanner reads text, photographs from paper, which are then converted into bit patterns for processing, storage and output. Scanners are widely used in desktop publishing (DTP) applications. Basically there are two types of scanners- hand held scanner and flatbed scanners.

9. Bar code reader

Data  coded  in the form of small  lines (known  as bars) are known  as bar code).  Bar codes  represent  alphanumeric data by a combination   of adjacent  vertical  lines (bars)  by varying  their width and the spacing  between  them.  They are used particularly  for unique  identification  of all types of goods, books,  postal packages,  badges,  tags, etc. A bar-code   reader  is  a device  used  for  reading  (decoding)   bar-coded   data.  It may  be  a hand-held   scanner,  or embedded  in a stationary  scanner.  It scans a bar-code  image and converts  it into an alphanumeric   value that is then fed to a computer  connected  to the bar-code  reader. A bar code reader uses laser-beam scanning  technology. A laser beam  is stroked across  the pattern  of bars of a’ bar code.  Different  bar codes  having  different  patterns  of bars  reflect  the beam  in different  ways  that  is sensed  by a light-sensitive  detector.   Reflected   light  patterns   are  converted   into  electrical   pulses   and  then  transmitted   to recognition  logic circuits  that convert  it into an alphanumeric   value.

10. MICR Device

MICR technology is being widely used in the field of banking. MICR device is used to recognize the magnetically charged characters (printed with special ink containing particles of iron oxide) given at the bottom of cheque. These characters. Are written by a special ink called magnetic ink. Other areas where MICR device issued are examinations in correction of large volumes of answer sheets, in market surveys, ordinary forms etc.

11. Optical Character Reader

Optical character reader (OCR) is a special kind of optical device, which is used to input the printed matter on a paper or any object. The text, which is to be scanned, is illuminated by a low frequency light source. The dash areas on the text absorb the light while light areas reflect it. OCR devices are used in application areas like reading PIN codes in postal services and reading passenger tickets. OCR  software  is extremely  complex  because  it is  difficult  to  make  a  computer   recognize   an unlimited    number   .of   typefaces    and   fonts. Hence,     these     software     are    designed     to recognize    texts   written   using   standard   type fonts  (called  OCR  fonts).  Two  such  standard fonts   are   OCR-A   (American    standard)    and OCR-B  (European   standard).  Note   that    if   the   document contains   italics   or  bold  face  letters,   or  fonts other than that for which the OCR software  has been   designed,    the   OCR   software   will   not work effectively.

12. Optical Mark Reader (OMR)

These  scanners  are capable  of recognizing   a pre-specified   type  of mark  made  by pencil  or pen. For example,  in objective type tests  applicants  mark their  choices  of correct  answers  on a special  pre-printed  test scoring  sheet by darkening  a small  square, circular,  or oval shaped  box by a pencil .  These  answer  sheets  are fed directly  to a computer  for grading  with the use of an optical  mark reader. The actual technique  used by an OMR device  for recognition  of marks  involves  focusing  a light on the page being scanned and detecting  the reflected  light pattern  from the marks.  Pencil  marks  made  with  a soft lead pencil  (high graphite  content)  reflect the light enabling  the reader to determine  which  responses  are marked.

13. Microphone

A microphone is a special multimedia input device used to store voice data consisting of recorded message or synthesized sound using GUI operating system such as Windows. Microphone converts sound waves into analog electrical signals, which are further converted to digital form in a PC.

14. Web Camera

A web camera is another special input device of a multimedia PC. It is used to capture and store digital data in the form of still and video images. It has become very popular on the Internet for chatting. People sitting across the countries see each other while chatting on net using a Web camera.

15. Electronic Card Reader

Electronic  cards  and  their  associated   readers  offer  another  means  of  direct  data  entry  into  a computer   system. Electronic  cards  are  small  plastic  cards  having  encoded  data  appropriate   for the  application   for  which  they  are used.  An  electronic-card    reader,   normally   connected   to  a  computer,   is  used  to  read  the  data  encoded   on  an electronic  card and transfer  it to the computer  for further  processing. Electronic  cards  are often  issued  by banks  to their  customers  for use with  automatic  teller  machines  (ATMs).