Table of Contents
Input Devices
An input device is any peripheral used to provide data and control signals to information processing system such as a computer CPU or other information system. Any machine that feeds data into a computer is called input device.
Input devices convert the user’s actions and analog data (sound, graphics, pictures) into digital electronic signals that can be ‘handled’ or ‘read’ by a computer.
CLASSIFICATION OF INPUT DEVICES
Many input devices can be classified according to its working.
- Character Input Device
- Keyboard
- Pointing Input Device
- Mouse
- Trackball
- Joystick
- Optical Input Device
- MICR
- OCR
- OMR
- Scanner
- Digital Camera
- Barcode Reader
- Light Pen
- Other Input Device
- Voice Recognizer
- Touch Screen
- Digitizing tablet
- Smart Card Reader
Keyboard
Keyboard is a character based input device. Similar to type writer with some additional keys like Function Keys (used to issue commands & also called as programmable keys), Special Purpose Keys (like ctrl, del, Ins), Cursor Movement Keys, & Numeric Keys.
When key is pressed, special standardized electronic code is created & sent to computer through cable. There it is analyzed and converted into appropriate computer usable code.
Keyboard’s Part
- Alphabetic Keys:-
- Alphabets like A to Z (capital & small latter)
- Function Keys:-
- F1 to F12 ( used for special functions)
- Related operating system and application software’s function.
- Control Keys:-
- Used for system controlling. Like- Enter, Shift, ESC, Pause, Numlock, Caps down, Ctrl, Alt.
- Editing Keys:-
- Used in application S/w for editing the document. Like- ↑, ↓, →, ←, Page up, Page down, Home, End, Back space, Space bar, Delete, Insert, Tab.
- Numeric Keys:-
- Provide facility just like calculator.
- Store Decimal Number and Basic operator.
- Symbol key:-
- Print special symbol like- ~, !,@, #, $, %, ^, &, *, (, ), -, _, +, =, /, ?, ., >, <, ,, {, }, [, ], \, |.
Mouse
- It is pointing device used in GUI environment.
- It is hand-held device connected to computer by small cable. Mouse is rolled across the desktop, accordingly cursor moves across the screen when cursor reaches the desired position; a button on mouse is pushed once or twice to signal a menu selection or a command.
- With the help of mouse, figures or pictures can also be created directly on the screen.
Trackball
Trackball is also a pointing device. Essentially, a trackball is a mouse lying on its back. To move the pointer, we rotate the ball with our thumb, fingers, or the palm of our hand. There are usually one to three buttons next to the ball, which we use just like mouse buttons.
The advantage of trackballs over mouse is that the trackball is stationary so it does not require much space to use it. In addition, we can place a trackball on any type of surface. For, both these reasons, trackballs are popular pointing devices for portable computers.
Joystick
A Joystick is also a pointing device. It is just like a lever that moves in all directions and controls the movement of a pointer or some other display symbol. A joystick is similar to a mouse, except that with a mouse the cursor stops moving as soon as we stop moving the mouse. With a joystick, the pointer continues moving in the direction the joystick is pointing. To stop the pointer, we must return the joystick to its upright position. Most joysticks include two buttons called triggers.
Joysticks are used mostly for computer games, but they are also used in CAD/CAM systems and other applications.
MICR (Magnetic Ink Character Recognizer)
This technology is used in banks. It involves the reading of numeric character and a few special symbols printed on cheques with magnetic ink. Alphabetic characters are not used with this technology.
- The standard character set for MICR consists of 14 symbols.
- In this system –
- Human involvement is minimal so less errors.
- It is fast, automatic & reliable.
- But the cheque amount has to be encoded in MICR characters manually.
OCR (Optical character recognition)
Optical character recognition refers to the branch of computer science that involves reading text from paper and translating the images into a form that the computer can manipulate (for example, into ASCII codes). An OCR system enables you to take a book or a magazine article, feed it directly into an electronic computer file, and then edit the file using a word processor.
OMR (Optical Mark-up Reader)
OMR has a high intensity light inside that is directed in the form of a beam at the sheets of paper being fed through it. The beam scans the marked forms & detects the number & location of the pencil marks. The data is then converted into electrical signals for the computer. OMRs come in variety of sizes & shapes that depend on the size of the forms to be read & the required loading & processing capacity of reader.
The optical mark technology is used widely for scoring exams & inputting raw data recorded on questionnaires. For OMRs to read the data correctly the forms must be carefully designed & manufactured and marks must be done carefully.
Scanner
Scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. There are two types of scanner available in current time one is sheet fed scanner and another is handheld scanner.
Light Pen
It uses a light – sensitive photoelectric cell to signal screen position to the computer. The pen is pushed to close the photoelectric circuit thereby indicating the XY screen co-ordinates to the computer. They are generally used by graphics designed.
Digital Camera
A camera stores images digitally rather than recording them on film. Once a picture has been taken, it can be downloaded to a computer system, and then manipulated with a graphics program and printed. Unlike film photographs, which have an almost infinite resolution, digital photos are limited by the amount of memory in the camera, the optical resolution of the digitizing mechanism, and finally, by the resolution of the final output device. Even the best digital cameras cannot produce film-quality photos.
The big advantage of digital cameras is that making photos is both inexpensive and fast because there is no film processing.
WEBCAM – A webcam is a video camera that feeds its image in real time to a computer or computer network.
Barcode Reader
Bar codes are recorded on the products by the manufacturers and usually carry inventory stock no. The coding scheme is called as Universal Product Code. The data recording is based on the width of the bars & the space between them. To read the bar codes, 2 types of scanning devices are used, Hand held scanner & counter top scanning device.
Hand held scanner is passed over the tag with bar code. The wand has scanning device that analyzes the light & dark bars for width & spacing, translating this data into electrical signals for computer.
Voice Recognizer
They convert the spoken words into electrical signals by comparing the electrical patterns produced by the speaker’s voice with a set of pre-recorded patterns. If a matching pattern is found, the computer accepts this pattern as a part of its standard vocabulary. Problems are limitations on size of computer’s vocabulary, pronunciation differences among individual & inability to accept continuous speech.
Touch Screen
The user touches the screen at the desired locations, marked by labelled boxes to point out choices to computer. The software determines the kinds of choices the user has. But limited amount of data can be entered via a terminal that has a touch-tone screen.
Two types touch screen technology available-
- Microwave
- Thin Film (Wire Grid)
Smart Card Reader 
A card reader is a data input device that reads data from a card- shaped storage medium. The first were punched card readers, which read the paper or cardboard punched cards that were used during the first several decades of the computer industry to store information and programs for computer systems.
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