Computer Input device

Definition:- When you work with the computer you enter your date and instruction through some devices to the computer. These devices are called input devices. The input devices are necessary to convert data or instructions enter into the computer to a form which can be recognized by the computer.

Some of the commonly used input devices are:

Keyboard is an input device used to input the data to the computer. The layout of keyboard is just like the traditional typewriter. The computer keyboard is rectangular or near-rectangular buttons, called “keys”. The characters are engraved or printed on the keys. A standard keyboard contains a total of 101 to 104 keys.
In addition to standard keys, a keyboard contains some extra command keys and function keys. These keys do not produce any symbol. But instead affect the operation of the computer or the keyboard itself.
There are various variations of keyboard that are available in the market such as multimedia keyboard, internet keyboard, folding keyboard and wireless keyboard.

Mouse is the pointing device used to move a graphical pointer on the screen. This graphical pointer is also called cursor. Using mouse you can give commands. Draw images and perform other input tasks.
Physically, a mouse consists of a small case, held under one of the user’s hands, with one or more buttons. When you roll the mouse across a felt surface, the screen censors the direction of mouse movement and cursor on the screen follows the motion of the mouse.
A mouse also has tow or its top surface. These buttons can be clicked or double-clicked to perform tasks, lie to select an icon the screen or to open the selected document.
There are several variants of muse available in market today. One of the most popular is optical mouse. An optical mouse doesn’t have a ball. It uses a laser to sense the motion of the mouse instead.



The keyboard can input only text through keys provided in it. If we want to input a picture a keyboard cannot do that. To input a picture we need a scanner.
A scanner is an optical device that analyzes images, printed text, or handwriting and coverts it to a digital image.
The common scanner devices are:
Magnetic Ink Character Recognition (MICR) reader

Optical Mark Reader (OMR) scanner

Optical Character Recognition (OCR) scanner

Barcode Reader

MICR Reader:-
MICR is widely used by banks to process large volumes of cheques and draft. The bottom line on all cheques and drafts has special characters printed in special font called MICR. Cheques are put inside a MICR reader. As they enter the reading unit the cheques pass though the magnetic field which causes the read head to recognize the character of the cheques.


OMR Scanner:-
OMR technique is used when students have appeared for objective type tests and they had to mark their answer by darkening a square of circular space by pencil. These answer sheets are directly fed to a computer for grading where OMR is used.
The OMR scanner puts a shining beam of light on the document and detects the marked area from unmarked ones. This I possible cause a marked area reflects more light in comparison to an unmarked area.



OCR Scanner :-
OCR is used for direct reading f any printed character. It translates images of handwritten or typewritten text, usually captured by a scanner, into machine-editable text. OCR is generally used in the field of pattern recognition, artificial intelligence and machine vision.
Suppose you have a set of hand written document you put a document. Inside the scanner of the computer, the characters in the document are compared with a site of patterns stored inside the computer, whichever patterns is matched is then successfully converted to machine-editable text , this is called a character read patterns that cannot be identified are rejected.
OCRs are more expensive than MICR.



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