Input Devices Of Computer And Their Function

What is input device?

Input Devices Of Computer And Their Function – Data and instructions are entered into a computer through input devices. An input device converts input data and instructions into a suitable binary form which is stored in the memory of a computer. The most commonly used input device is the keyboard. A number of other input devices, also known as pointing devices, have also been developed which do not require data entry by typing. Examples include mouse, light pen, graphic tablet, joy stick, track ball, touch screen, etc. 

Function Of Input Device

An input device performs the following functions
(i) It accepts the instructions and data from the user.
(ii) It converts these instructions and data in computer in acceptable format.
(iii) It supplies the converted instructions and data to the computer system for further processing

Some Example Of Input Device

1. Keyboard
2. Mouse
3. Joystick
4. Trackball
5. Scanner
6. Barcode Reader
7. MICR
8. OMR
9. Web Camera
10. Biometric Sensor
11. Light Pen
12. Voice Input and Recognization System
13. Card Reader
14. Video Cameras
15. Graphics Tablet
16. Touch Screen
17. Touchpad (Trackpad)
18. Microphone
19. Digital Camera

Keyboard

Keyboard is one of the most common input devices. The user can type text and command using this device. The layout of the keyboard was borrowed from the regular typewriter with some additional keys. Keyboard is used to enter data or information in a computer system, which may be in numeric form or alphabetic form. There are different types of keyboard such as QWERTY, DVORAK and AZERTY.

Types Of Keys On Keyboard

1. Alphanumeric key :- Include the alphabet key(A, B ,c……z and number keys(1,2,3……….9).
2. Number key :- Are located at the hand side of the keyboard. they consist of digits and mathematical operators.
3. Function key :-Are the programmable key, they are numbered from f1 to f12.
4. Cursor control key :- Include four directional (left, right, up, down) .                  there are four more keys to control the cursor                                                        home,  end, page up, page down. 
5. Other keys :A key board contain some other keys such as follow………..               
6. control key- It performs a special operation with the combination of other key. 
7.  Enter key- It is used to finish an entry and begin the new entry in a document.
8.  Shift key- Shift key is used to print the symbols on which is printed on the numeric pad on the upper portion. 
9. Escape key- It allows a user to cancel or abort operation . 
10. Backspace key- It is used to erase anything typed.
11. Delete key- It is used to erase information from the computer. 
12. Caps lock key- It is used to type the alphabet in capital letters. 
13. Num lock key- It is used to unable or disable the numeric keypad.
14. window key- It is used to open the Start Menu. 
15. Spacebar key- it provides a space between two words . it is the longest key.
16. Tab key- it is used to the cursor over to the right to the pre-set point . 

Mouse

Mouse-  The mouse is a pointing device that allows to control the movement of pointer (also known as mouse pointer) on screen. Mouse performs various functions by detecting two-dimensional motion relatively to its supporting surface. A mouse can be of different types like wired, wireless mouse, optical mouse, mechanical mouse etc. Generally a mouse have two buttons – a right button and left button. mouse also include a scroll wheel between the button to scroll down the application window and their contents also

Different Types Of Mouse

1. Optical mouse
2. Mechanical mouse
3. Wireless mouse

Mouse Action

Left Click           : Used to select an item.
Double Click     : Used to start a program or open a file.
Right Click         : Usually used to display a set of commands.
Drag and Drop : It allows you to select and move an item from one location another.

“Mouse was invented by Douglas Engelbart at Stanford Research Centre in 1963“. Optical Mouse was Introduced by Microsoft in 1999. It uses a light beam to detect the Movement

Joystick

Joystick– is also a pointing device like the mouse, which consists of a stick that pivots on a spherical ball on its base. A joystick is similar to a mouse excepts that the moment of cursor on screen stops working as soon as user stop moving the mouse. But with a joystick, the pointer continuous moving in the previously pointing direction. Commonly, joysticks are used for playing computer games like flight simulators but occasionally used for CAD/CAM systems and other applications. 

Trackball

Trackball- is designed for computers, generally mouse replacement. It is primarily used to move the cursor on the screen. The Trackball has a ball on its top. Trackball Trackball can be rolled with fingers and the internal rollers sense the motion, which is transmitted to the computer. Trackballs are common on CAD workstations and sometimes seen on computerized special purpose work stations, such as the radar consoles in an air-traffic control room or sonar equipment on a submarine.

 Scanner

Scanner- read or display the scanned object. Scanners can be used for storing the documents in their original form that can be modified and manipulated later on. It is mainly used to convert a scanned document in a digital format. Scanners come in a variety of sizes from hand-held models to desktop models as discussed below:

(i) Hand-held Scanner
(ii) Flatbed Scanners
(iii) Drum Scanners

 Barcode Reader

Barcode reader– It is an input device used for reading printed bar codes (Universal Product Code) available on product to be sold. A bar code reader emits a beam of light, which reflects off the bar code image.  A light sensitive detector in the barcode reader the see  identifies the bar code image by recognising special bars at both the ends of the image. 

 MICR

(Magnetic Ink Character Recognition)-MICR reads the characters by examining their shapes in a matrix form and the information is then passed on to the computer. The characters are printed using a special ink, which contains iron particles that can be magnetised. It is generally used in banks to process the cheques for recognising the magnetic encoding numbers printed a the bottom of a cheques.

 OMR

Optical Mark Readers (OMR) are special scanners used for recognising a pre specified type of mark made by pencil or pen. For example, in the objective test paper of DOEACC (Department of Electronics Accreditation for Computer Courses), you mark your answers on a special sheet by darkening a small square, using a pen or pencil. These answer sheets are fed into the computer using the optical mark reader. The computer can then evaluate the answer sheets.

 

Web Camera

Web camera- Allows a computer to accept input just by focusing on an object. The camera is focused on the input object to take a picture of the object. A picture so taken can be transferred over the computer network to a distant place. The image of the object can be seen on the monitor of the distant computer connected through a network or through the Internet.

 Biometric Sensor

Biometric sensor– It is a device which recognises physical or behavioural traits of the individual. Biometric sensors are mainly used marking Biometric attendance of employees/ students in organisations /institutions. Biometric sensors are working with accuracy  so these are  widely used in security purpose also.

Light Pen

A light pen is a pointing device shaped like a pen and is connected to a monitor. It is a photosensitive pen- like device capable of sensing a position on the monitor screen when its tip touches the screen. When its tip is moved over the screen surface, its photocell sensing element detects the light coming from the screen and the corresponding signals are sent to the processor. The menu is a set of programmed choices offered to the user. The user indicates his choice by touching the light pen against a desired description of the menu. The signals sent by the light pen to the processor identify the menu option. A light pen is also used in handheld PAD type small devices for writing small messages and sending them over e-mail.

Voice Input and Recognization System

Voice input and recognition system is an input device, consisting of a microphone or telephone that converts human speech into electrical signals. A signal pattern obtained in this manner is sent to the computer where it is matched against pre-stored patterns to identify the input. When a close match is found, a word is recog- nized by the system.

Uses of Voice Recognition System

This feature is used where a person wants to input data to a computerized system, especially in situations where his hands are busy, or his eyes have to remain fixed on a measuring instrument or some other object. The feature is used by security systems for identifying authorized users of the system

Card Reader

A card reader is a device that reads punched cards. A punched card is a storage medium made of thick paper card that holds data in the form of punched holes. The holes are punched into the card by a key punch machine or card punch peripheral device connected to a computer.

The punched card code is detected by patterns of light passing through the holes in the cards.

Another card reader, called magnetic card reader, is used for reading the magnetic strip on the back of credit cards and transferring data sent through the card.

Video Cameras

A video camera takes continuous pictures and generates a digital or analog signal for display on a monitor or for permanent recording. Signals generated by video cameras are traditionally analog, but nowadays digital video cameras are available. The latter converts analog signals into digital form.

A video camera captures images by breaking down the images into a series of lines. Each line is scanned one at a time and the continuously varying intensities of red, green and blue light across the line are filtered out to convert into a continuously variable (analog) signal. These are then used for sending a picture over a network through computers.

Graphics Tablet

A graphics tablet (or digitisers, digitising tablet, tough tablets or simply tablet) is an input device that consists of an electronic writing area and a special pen that works with it. It allows artists to create hand-made images and graphical images with motion and action, similar to the way a person draws images with pencil and paper.

The pen of the graphics tablet is pressure sensitive, so pressing harder or softer can result in brush strokes of different width.

When user draws anything on the tablet with the special pen, the drawing appears on the screen.The tablet and pen can also be used like a mouse to move the cursor and click. Graphics tablet may also be used to capture data or handwritten signatures.

Touch Screen

It is an electronic visual display that can detect the presence and location of a touch within the display area. The term touch screen generally refers to touching the display of the device with a finger or hand. The touch screen sends a signal to the computer. This signal gives the location on the screen, which has been touched. Touch screen is quick and simple to use. Generally, smartphones have a high-resolution capacitive touch screen.

There are different types of touch screens available with electronic devices like capacitive touch screen, resistive touch screen and gorilla glass touch screen, etc.

Touch screen is pressure sensitive and activated by finger or stylus.

Touchpad (Trackpad)

It is a specialised surface that can translate the motion and position of a user’s finger to a relative position on the screen. This is a common feature of laptop computers and also used as a substitute of a computer mouse, where disk space is scarce. The sensors of touchpad only react through fingertip and not a pencil or other object.

There are usually two buttons next to the touchpad which works as left and right button of the mouse.

Microphone (Mic)

We can send sound to the computer through a special manual input device called microphone or mic. A mic converts the received sound into computer’s format, which is called Digitised Sound or Digital Audio. To convert a voice into digital form, an additional hardware is always needed which is known as Sound Card.

A microphone can be attached to a computer to record sound. Now-a-days, microphones are also being used with speech recognition software. This means that you do not have to type the document, rather just have to speak and the spoken words appear in your document.

Digital Camera

It is a device that stores the pictures or videos in an electronic format instead of film. There are several features that makes digital camera a popular choice, when compared to film cameras. Most enjoyable feature is the LCD display on the digital camera. This display allows users to view and save photos or video after the picture or video has been taken, that means, if you take a picture and don’t like the results, you can delete it, or if you like the picture, you can save it and easily show it to other people.

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