What is scanner and its types

What is scanner?

A scanner is an input device that captures documents such as photographs and text. Scanners are of many types according to their design, scanning mechanisms etc. When a document is to be scanned, firstly a documents is converted into digital signal and then scanning is performed on this electronic version of document.

A scanner can be connected to computer using different interface such as SCSI, TWAIN etc, but today the most common method is USB cable.

TYPES OF SCANNER

FLATBED SCANNER

Flatbed scanners will take up some desktop space but provide a lot of bang for the buck. They look like miniature printers with a flip-up cover protecting the glass platen. Flatbed scanners are some of the most commonly used scanners as it has both home and office functions. The way they scan documents is that a mechanism rolls under the document to obtain the image. For a businesses that have a need for high processing abilities, the flatbed scanner can scan any number of documents with a click of a button.

SHEET-FED SCANNER

Sheet-fed scanner is smaller in size than flatbed scanner. This type of scanner works like a flatbed scanner except that the document is fed through the scanner and moves along the beam to be read rather than the beam moving along document. This type is not useful for books, but only single sheets.

A small size is its advantage but improper mechanism can skew the paper.

DRUM SCANNER

Drum scanner is used for scanning a document and produce at very high resolution rate. There is no any type of scanner that will give you the kind of resolution, detail, sharpness, dynamic range, and color rendition that drum scanning can give you. There are only a few companies that make these scanners, considering the high cost of producing a scanner such as this. It is considered as a tremendous upgrade to a regular flatbed scanner.

A drum scanner uses a photo-multiplier (PM) tube, which is a light sensing device. That's why it offers a high sensitivity and good signal-to-noise ratio. The image to be scanned is placed on spinning.

HANDHELD SCANNER

Handheld scanner is much like a flatbed scanner. Handheld scanners are small helpful electronic devices that are widely used for digitizing printed documents. Handheld scanner provides lower quality scanners, they are still very popular because they are small and less expensive than their flatbed. They are able to scan items that could not fit in a flatbed scanner due to size or location. Their function includes moving them over the material being captured with the aid of a tray to keep it in a straight line. Experience is required to operate and handle the device since it is very important to keep the scanner straight so that a distortion-free scan is possible.

Low cost and portability is the advantages of handheld scanner but poor quality is its drawback.