Input Devices Contents Introduction - PowerPoint Presentation

Slide1

Input Devices

Contents

Introduction

Common Input Devices

KEYBOARD

WORKING OF KEYBOARD

MOUSE

WORKING OF MOUSE

JOYSTICK

TRACK BALL

SCANNER

WORKING OF A SCANNER

TYPES OF SCANNER

MAGNETIC INK CARD READER (MICR):

OPTICAL CHARACTER RECOGNITION(OCR):

OPTICAL MARK READER (OMR)

Introduction

In

 computing, an 

input device

 is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Input devices are components or peripheral devices that feeds data or instructions into a computer or other computational devices for display, storage, processing, or outputting or transmission. They convert the instructions and analog data like graphics, sound, pictures into digital signals that can be processed by a computer. Examples of input devices are mouse, bar-code reader, magnetic-stripe reader, keyboard, modem, scanner, graphic tablet and stylus.

Back

Keyboard

Mouse

Joy stick

Track Ball

Scanner

Magnetic Ink Card Reader(MICR)Optical Character Reader(OCR)Optical Mark ReaderCommon Input Devices

Back

Key points regarding keyboard:

The keyboard is the standard

input device.

It is merely collection

of keys.

It allows us to communicate with computer.It is similar to typewriter. Typewriter record data on paper but in keyboard data is stored in memory.A standard keyboard has 101/102 keys

and also known as QWERTY keyboard.

Keyboard

SR. NO.

KEYS

DISCRIPTION

1.

TYPING KEYS

These keys include the letter keys (A-Z) and digits keys (0-9) which are

generally give same layout as that of typewriters.

2.

NUMERIC KEYS

I t is used to enter numeric data or cursor movement. Generally, it consists

of a set of 17 keys that are laid out in the same configuration used by most

adding machine and calculators.

3.

FUNCTION

KEYS

The twelve functions keys are present on the keyboard. These are arranged

in a row along the top of the keyboard. Each function key has unique

meaning and is used for some specific purpose.

4.

CONTROL KEYS

These keys provides cursor and screen control. I t includes four directional

arrow key. Control keys also include Home, End, Insert

, Delet ,page up, page down Control(Ctrl), Alternate(Alt), Escape(Esc).

5.

SPECIAL PURPOSE KEYS

Keyboard also contains some special purpose keys such as Enter, Shift,

Caps Lock, Num Lock, Space bar, Tab, and Print Screen.

When any key is pressed in keyboard, the spring blow presses down thus completing the circuit. The tiny chip KEYBORDS CONTROLLER notes which key is being pressed. It sends interrupt request to the O.S. It also sends a code called

scan code

to the KEYBOARD BUFFER the system software respond to the interrupt by reading scan code this scan code is combination of bit patterns is then passed to CPU .the ASCII code using appropriate software's in the computer for that bit pattern which is transmitted to an external device for I/O processor.

WORKING OF KEYBOARD

Back

Stanford research center invented

the first mouse on 1965.

It rolls on a small ball and has two or

three buttons on the top.

The cursor moves very fast with mouse

giving you more freedom to work in any direction.It is easier and faster to move through a mouse.It s user-friendly for computer beginners.A mouse is easy and convenient to use with a graphical user interface.

MOUSE

There is a small ball underneath a mouse , the ball moves too. As the ball moves it rubs against two rollers. One roller senses the horizontal movement and other vertical. These rollers together can tell in which direction the user moves the mouse. Each roller is attached to a wheel called ENCODER. This encoder turns with the rollers. As the encoder turns, its metal bridges touches two fixed electrical contact which generates electrical pulses. The movement of mouse tells with which rate the electrical pulse is generated. These signals are send to the computer through mouse cables. These signals are read by software called the MOUSE DRIVER. This software tells your computer how to move mouse pointer so that it matches mouse movement.

WORKING OF MOUSE

Back

Joystick was discovered by Robert

Esnalt-Pelterie

on 1st

jan

. 1909.Robert Esnalt-Pelterie came up with the idea of the joystick in his diary.It works on the principle of trackball.The first joystick was used to fly a plane,.Today they are commonly used

in video games.

Joystick

Back

Track ball is an input device

that is mostly used in notebook

or laptop computer.

A trackball is good for limited desk

space because the user does not have to

move the entire device.A trackball is usually not as accurate as a mouse.The ball mechanism of trackballs also requires more frequent cleaning than a mouse.Track Ball

Back

Roudolph Hell invented a

scanner on 1

st

Jan. 1963.

The purpose of this object is to

scan documents, pictures etc. Electronic format of scanned image is its bit map representation.Stored image can be altered or manipulated with an image processing software.

Scanner

Scanners operate by shining light at the object or document being digitized and directing the reflected light (usually through a series of mirrors and lenses) onto a photosensitive element. In most scanners, the sensing medium is an electronic, light-sensing integrated circuit known as a charged coupled device (CCD). Light-sensitive photosets arrayed along the CCD convert levels of brightness into electronic signals that are then processed into a digital image.

Two other technologies, CIS (Contact Image Sensor), and PMT (photomultiplier tube) are found in the low and high ends of the scanner market, respectively. CIS is a newer technology that allows scanners to be smaller and lighter, but sacrifices dynamic range, depth-of-field, and resolution. PMT-based drum scanners produce very high-quality images, but have limited application in library .

Another sensing technology, CMOS (Complementary Metal Oxide Semiconductor), appears primarily in low-end, hand-held digital cameras where its low cost, low power consumption and easier component integration permits smaller, less expensive designs.

Working of a Scanner

Flat Bed Scanner

Hand Held Scanner

Flat Bed Scanner

:

Looks like a photocopy machine.

Has a box with a glass plate on the top & a lid.Document to be scanned is placed on the glass plate.A light source below the glass plate moves from one line to another and scans all these files.Take few seconds to scan a document.

Types of Scanner

Hand Held Scanner:

Contains LED and can be held on hand.

To scan dragged slowly over

the document from one end to another.

It has to be dragged very slowly and

steadily.Used only when light accuracy is not needed.It is cheaper than the flat bed scanner.Used when the volume of the document to be scanned is low.

Back

MICR is used by banking industry for

faster processing of large volume of

cheques

Bank’s identification code (name, branch

etc.), account number and

cheque number are pre-printed (encoded)using characters from a special character set on all chequesSpecial ink is used that contains magnetizable particles of iron oxide

MICR reader-sorter reads data on

cheques

and sorts them for distribution

to other banks or for further processing.

MAGNETIC INK CARD READER (MICR):

Back

‘Its the mechanical or electronic conversion of scanned images of handwritten, typewritten or printed text into machine-encoded text’.

OPTICAL CHARACTER RECOGNITION(OCR):

Back

‘Optical mark recognition (also called optical mark reading and OMR) is the process of capturing human-marked data from document forms such as surveys and tests’.

OPTICAL MARK READER (OMR)

Back

Thank You