Scanners

The world seems to be in a conspiracy to eradicate analog content and supplant it with digital content. Scanners are the instruments made to serve just that purpose! Scanners can be roughly classified into two categories: 1) Image Scanners and 2) Text Scanners. Although each can be used in the place of the other it is advisable to use them for the specific purpose they have been designed for. These scanners use esoteric principles of ray optics to transform an image or printed/hand written text to its digital counterpart.

Working principle of device:

The most common kinds of scanners are flatbed scanners and hence this section illustrates the working of a flatbed scanner.

The visible portions of a flatbed scanner consist of a lid and a glass plate. The lid often has a white sheet (black sheets are also not uncommon!) on its inner side which provides a uniform background while scanning a document. One can easily pop the lid off in case the object to be scanned doesn’t fit in the space available between the lid and the glass plate. Unfortunately, this facility is not available in all scanners. Once the document is fed in the scanner a Xeon Lamp or a Cold Cathode Fluorescent Lamp (CCFL) is lit. To begin the scanning process, the scan head (consisting of optical instruments such as mirrors, lenses and a CCD array) needs to move across the length of the document on the glass plate. A stepper motor, which is attached to the scan head, is actuated moving it to slowly along the length of the paper. Apart from the motor, the scan head is also attached to a stabilizer bar which ensures that its movement is not jittery.

The scan head contains either 2 or 3 mirrors. The image formed on one mirror is then reflected to the other. The last mirror incidents the final image onto a lens which then focuses it on a CCD array via a filter. The CCD array is a collection of photosites (light sensitive diodes) that convert light (photons) into electrical charge (electrons). Certain fastidious scanners use three pass scanning method in which every time a different colored (from red, green and blue) filter is used. The three images so formed are fused into a single colored image.

Device installation: The scanner requires its own software and/or driver to function correctly. It connects to the computer via USB port.

Manufacturer of device, its models and prices:

1.     HP – Scanjet 200 Flatbed (Rs. 4,499), Deskjet 2131 All-in-One Printer (Rs. 2,299), 3000S2 Scanjet Scanjet Sheet Feed scanner (Rs. 24,231), N1920 Document Flatbed (Rs. 1,80,000) etc

2.     Canon– Canonscan Lide 120 (Rs. 3,503), Canonscan Lide 220 (Rs. 5,355)

3.     Epson – Perfection V39 (Rs. 15,355), Scanner V370P (Rs. 8,054),

4.     Kodak –I940 Scanner (Rs. 24,000), I2420 Scanner Single (Rs. 48,900) etc.

5.      Panasonic – KV-S1027C/US Document Scanner (Rs. 1,00,546), KV-S1065C Document Scanner (Rs. 1,38,079) etc

 

Standard Configuration of device: Scanners generally come in four different shades:

1) Flatbed – Most common, desktop scanner

2) Sheet-Fed – resembles a printer. Scan head remains stationary while the pages move through

3) Handheld – User has to move the page through the scanner instead of a motor doing that. Very poor in quality as it requires manual efforts

4) Drum – Used in industries to obtain very high resolution images

Cost: Low end scanners can be bought under Rs. 5,000 whereas Industry grade scanners can potentially cost lakhs!

Market share of different models (Standard companies only):

l  HP

l  Canon

l  Epson

l  Kodak

l  Panasonic