Page 20 - Viva ICSE Computer Studies 7 : E-book

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 makes the movement of the
screen pointer accordingly.
Optomechanical mouse is similar to a mechanical mouse except that it uses optical sensor to
detect the movement of the ball on the mouse pad.

Optical mouse, which is most commonly used, has no mechanical moving parts, as it uses laser
beam to detect the movement of the mouse on the mouse pad.

Mechanical mouse Optomechanical mouse Optical mouse
Scanner

A scanner reads text, photographs or graphics from paper, which are then converted into bit
patterns for processing, storage and output. Scanners are widely used for desktop publishing
(DTP) and graphics applications. Generally there are three types of scanners: drum scanner,
handheld scanner and fl atbed scanner.
Drum Scanner

A drum scanner is the one which uses a photomultiplier tube
(PMT) to scan images. Photomultiplier tubes are vacuum tubes
which are extremely sensitive to light. In drum scanners, the
image is mounted on a glass tube. When the beam of light
moves across the image, its refl ection is picked up by the
PMT and processed. Drum scanners are known for their high
resolution and are used in the publishing industry. If they are
not as popular, it is because of their cost and large size.

Handheld Scanner
A handheld scanner is a small manual scanning device which is
moved over the object that needs to be scanned. In a handheld
scanner, you have to drag the scanner over the document that
is to be scanned. Even a slight movement of the hand can lead to
distortion of the image. One of the most-utilised handheld scanner
is the barcode scanner, typically used in shopping stores to valuate
goods.

Flatbed Scanner

A fl atbed scanner derives its name from the fact that its glass
plane or bed, where the object to be scanned is placed, is fl at.
A fl atbed scanner is made up of a glass pane and a moving
optical CIS or CCD array. The image, the one that is to be scanned,

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