Scanners are electronic devices, generally used with a PC, which can read an image from a paper or a book and transforms it into a format that can be stored, sent, edited or printed from the host PC. Scanners work by the principle of light reflection – the scanner illuminates an image and measures the light reflected by it. These reflections are converted into specific voltages which are then transformed into an arrangement of dots that is similar to the original image.
There are four different types of scanners available in the market – sheet-fed, hand-held, flatbed and drum. Sheet feed scanners are those that can scan sheets of text only, and cannot read images or text from books, or other thick sources. Sheet feed scanners work by feeding documents into a hopper in a sequence. They are placed in line before being fed into the scanner individually. A series of rollers with a spacing equivalent to the thickness of a single sheet of paper draws is the waiting document when its turn arrives. A viscid conveyor pulls in the paper completely into the scanning surface as the document enters the machine.
On reaching the scanning surface, the document is illuminated with the help of a scanning wand that moves underneath the document. The scanning wand normally moves in a vertical motion along the length of the document. The speed of the wand depends on the quality and model of the scanner being used. The reflection of the document produced as an effect of the illumination is then interpreted by the scanner as a series of zeros and ones to produce a digital illustration of the document. When the document has been scanned, it is ejected from the scanner.
While ejecting the document, the conveyor that previously pulled the document in, forces the document out of the scanning surface. A string of gears and rollers then pulls the document out of the scanner, and into an assigned holder. Then in the same procedure, another document, if any is queued, is pulled into scanner and goes under the same scanning process.
Sheet feed scanners can cost less than $90 to more than $4,510. Sheet feed scanners are produced by a number of well-known computer hardware manufactures including Hewlett-Packard, Fujitsu, Canon, Visioneer etc. A moderately priced sheet feed scanner can come at a price of around $4,500 to $9,000, like the HP Scanjet 500 model at $542.00 and the Fujitsu fi-6130 at $875.99.
Sheet feed scanners have been integrated to become portable and affordable in recent years. Brands like IRIS, Neatreceipts and Xerox have developed portable sheet feed scanners that take up minimal space and can be carried along with the user. The IRIS IRIScan Express 2 sheet feed scanner costs around $117, which is pretty inexpensive if compared to the bulkier counterparts. The Xerox Travel Scanner 100 is yet another similar product that is priced at $135.99. A better option amongst such is the Neatreceipts Scanalizer Professional priced at $172.99. This compact and intelligently designed scanner is a pleasure to work with, and can be carried along if required by the user.
Sheet feed scanners are best only if the user wants to scan papers and documents. It is important to remember that sheet feed scanners can only scan individual sheets of paper, and cannot scan from a bundle of documents, unlike a flatbed scanner. Scanners should be checked for maintenance at regular intervals to make sure that all the components are working properly. With proper use and care, sheet feed scanners, or any scanner for that matter of fact, can last for years.