Kinds of Scanners


Tuesday, February 10, 2004


Computer Peripherals


There are several types of scanners, used for different modes of scanning.


A. Flatbed scanners also known as desktop scanners. The most widely used scanner and the most versatile, looks a lot like a photo copier; the object being scanned is placed on a glass platform under which the reading head moves.


Pros‑


• easy to use,


• permitting the scanning of objects of a wide range of sizes and even of 3‑dimensional objects.


Cons‑


• Big and Bulky


• Not travel size


B. Sheet‑Fed Scanners They resemble a lot a fax machine or a small portable printer because the page being scanned is moved across the reading head. Some of them scan only one page at a time, while others come together with a drawer so that they can scan multiple pages successively. Pros‑


• compact


• don't take up much room


• portable


Cons‑


• not the best quality images


• not able to maintain a constant speed of the page moving over the rereading


C. Drum Scanner These are older than the flatbed and sheet‑fed scanners. However, they offer the best‑quality images because they work with PMT (photomultiplier tube) sensors, while other scanners use CCD (Charged‑Couple Device ) or CIS (Contact Image Sensor).


Pros‑


• Best Quality


• permitting the scanning of objects of a wide range of sizes and even of 3‑dimensional objects.


Cons‑


• Older


• Not portable and very big


D. Hand Scanners It looks like an oversized computer mouse which allow the user to scan image as wide as 10 centimeters. In this case, the scanner is moved across the surface to be scanned, so the user must maintain a constant speed of the hand to obtain an average‑quality result.


Pros‑


• Quick scans


• Very portable


• Memory


Cons‑


• Not widely used


• Long transfers


E. Yet another kind of hand‑held scanners are the 3D scanners. They are very versatile scanning a large variety of materials and colors, including black, they work in almost any lighting conditions. They contain Windows NT compatible software that outputs data in a variety of standard formats.


Pros‑


• Very versatile


• Has many formats


Cons‑


• Most expensive


• Not used much


Some items demand special handling during scanning. Slides, for instance, require a scanner that passes light through the image rather than reflecting off light off it. Because of their small size, slides also need to be scanned on a unit with very high resolution (in other words, a lot of eyes on the scanning head).