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Saturday, 2 October 2010

How Does A Flatbed Document Scanner Work?

By Daniel Kilburn

It may shock you to find out that scanners have been around for almost 100 years - but with developments over the last few years, scan quality and functionality has rapidly increased, whilst making it more affordable to have within the home as well as the office.

So, How Does a Flatbed Scanner Work?

In terms of home and office computing, a flatbed document scanner is simply a device that can scan and convert photos or paper documents into a digital format. It is composed of a glass scanning bed (or plate), underneath which is either a bright light to illuminate the glass and a moving optical detector to scan the image - or a moving set of red, green and blue LEDs, strobed for illumination with a photo-diode for light collection.

How To Use a Flatbed Scanner

When a user wants to scan, the user lifts the hinged lid of the scanner and places the document to be scanned face down on the glass scanning bed and an opaque cover placed over it to exclude ambient light, ready for the image sensor and light source to pass beneath. The image is only visible to the detector because of the light it reflects - transparent images require special illumination from the top-side. Once the photo or document has been scanned, the image is sent from the flatbed scanner to the attached PC where it is displayed on the monitor screen ready to be saved, modified, e-mailed or printed.

How to choose a Flatbed Scanner

If you are looking for a scanner for use at work or in the home - you firstly need to know what you want to use the scanned images and documents for. If you are planning to print or display high-quality images from high-quality scans or photographs and you require no loss of detail, then you will need a flatbed scanner with a high colour-depth (48-bit or higher) and a high resolution (9600dpi or higher). If you are planning to archive your scanned text documents or add scanned images to electronic-documents and presentations, choose a scanner with a lower colour-depth (24-bit or lower) and a lower resolution (around 600dpi). These will produce satisfactory scans. Today's scanners also come with a wide variety of features, to make your scanning experience easier and simpler - they have features such as zero warm-up times, 3 second previews, 1 second scans and auto scan. Others also have built-in film adaptors and the ability to scan to e-mail and searchable PDFs. If you need this kind of functionality, make sure you find one that delivers for you.

The advantages of a Flatbed Scanner

There are many advantages of choosing a flatbed scanner for work or for the home. Firstly, with double-hinged lids, scanners allow you to scan thicker documents, books and even three dimensional objects. Secondly, flatbed scanners allow you to adjust the document into the correct position via visual markers. Also, with built-in negative and film holders, yesterday's memories can be scanned into a modern digital format - and by removing the lid, it can work as an improvised digital camera by taking an image of a three dimensional object

The disadvantages of a Flatbed Scanner

Flatbed scanners have two main disadvantages. Firstly if you are planning to scan many documents, because each scan has to be performed individually, then this can take time - however a sheet-fed scanner is the recommended replacement. Some scanners can also be quite large - especially A3 models - but as they are usually quite thin, they can be quite easily be stored on their side.

The death of the flatbed scanner was announced far too early with the revolution of the digital camera - especially as today's scanners have developed much higher colour depths and resolutions. Their ability to digitise 35mm film and negatives and to scan documents for e-mail has made the flatbed scanner even more important in the modern home and office than ever before.

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