Scanners

Scanner reads data or information from a source. This source could be a written document, a price tag, a graphic image or a photograph. A scanning device reads the data or information and then converts it into a form that can be processed by the system unit. Two types of scanning devices are optical scanner and optical readers.

• Optical Scanner

An optical scanner is also known as scanner. It is light-sending input device. It reads printed text and graphics and translates it in digital form. The scanned image can be used for different purposes as follows:

• It can be displayed on screen.

•  It can be printed on the paper.

• It can also be sent via email. 

• It can be posted on a web page.

• It can also be stored permanently for later use.

The typical image scanner scans at a resoultion of 300 or 600 dpi. Resolution describes the sharpness of an image. The quality of scanned image also depends on the resoultion. The scanned image will be brighter and sharper if the scanner provides high resolution. Professional scanners usually scan at 1200 dpi or higher. A higher number of dots generates better quality but also creates a larger file size. Many scanners also provide optical character recognition (OCR) software. OCR software can read the document image and then convert it into text that can be edited in word processor.

• Types of Optical Scanner:

Different types of optical scanners are as follows:

1. Flatbed Scanner:

A flatbed scanner is also called image scanner. It inputs one page at a time. It works like a photocopy machine. The image to be scanned is placed on a glass surface and the scanner records the image. It is generally used at home and office.
2. Sheet-fed Scanner:

A sheet-fed scanner works similarly to a flatbed scanner but documents are inserted on the top of the scanner like a fax machine. This design reduces the scanner's cost and the amount of required space. It also enables automatic sheet feeding. However, this feature also prevents the device from scanning bound-book pages or other documents thicker or larger than a sheet of paper.

3. Handheld Scanner:

A handheld scanner is a portable scanner. It is also called half- page scanners because it can scan only 2 to 5 inches at a time. Handheld scanners are useful to input small amount of data. The scanner must be moved over the image to be scanned by hand. Some handheld scanners include trays to keep the scanner moving in a straight line. It is designed to scan short articles and single lines of data like web addresses, names or phone numbers.