Barcode scanners and reading devices use a light source and what is known as a photo conductor or light sensor to decode printed barcodes. They also contain decoder circuitry which allows the data to be sent to an output port – such as a pc or point of sale system, where the code can be used to retrieve information on the item which has been scanned.
Barcode scanners and readers are utilised to read linear – or one-dimensional – barcodes. Due to the increasing popularity of 2D barcodes such as QR, Aztec and DataMatrix codes, specialised barcode imagers are also available. These can also be scanned with a cellphone camera (if the device has this functionality) or in smartphones via a barcode scanning application.
Types of One Dimensional barcode scanners:
This is the oldest form of barcode scanner, and they are rarely used anymore outside of small operations. The scanner is dragged across the barcode, and has to be in contact with the code. Because it may have to be passed back and forth several times before the code is read this form of scanner is only suitable for operations where a small number of barcodes need to be scanned daily. Because the movement of the wand will vary, the scanner works by decoding the rate of change between dark and light against a set clock.
Laser scanners are similar to pen scanners in that they both use their own light source to read the barcode via a photodiode. In the case of laser scanners however, laser beams emitted by the scanner are captured via an oscillating prism which sweeps back and forth across the bar code many times a second; and polygon mirrors which convert the diffuse reflection of the barcode to a denser, readable format, and therefore allow for scanning from a distance. They can be stationary or handheld and are the scanners most commonly used in the retail sector.
CCD (charge-coupled device) barcode scanners come in both short and long range versions, and connect to a computer via a cable, usually to a USB port. They work off of the basis of a laser diode which was originally invented by the Japanese in 1987 and quickly took over the scanner market. Hundreds of tiny light sensors are lined up at the head of the reader, and essentially mimic the pattern of the barcode in order to decode it. Long range CCD scanners generally have the ability to read 1 and 2-dimensional barcode images.
Types of Two Dimensional barcode scanners:
As the name implies, these scanners allow for the barcode to be read from any angle, and some larger retail stores have begun to adopt them. They are often read in stores by sliding the barcode across a glass plate. They are especially useful when your hands are not free to hold a scanning device. Unlike laser scanners, they produce a pattern of light beams in several different orientations, and are especially useful for reading damaged or poorly printed barcodes.
Video camera readers:
This is one of latest 2D barcode imagers. They work on a similar basis to a CCD barcode reader, except that they have sensors arranged both vertically and horizontally. The lights flash onto the barcode, and create a digital picture of the code in order to read and decode it.
Smartphone and cellphone camera scanners:
Some barcodes such as QR and DataMatrix codes can be optimised to allow them to be read by most cellphones with a camera. Of course, all of today’s smartphones can scan barcodes via a pre-installed (such as Nokia’s Symbian system, or the BlackBerry App World barcode reader device) or downloaded app, of which there are hundreds of free versions available.
As barcodes and barcode symbologies have improved over the years, barcode scanners and imagers have evolved with them. From humble beginnings like the pen scanner which could take minutes to scan just one barcode, to large industrial imagers that can decode a vast array of barcodes in milliseconds. With a barcode scanner basically now in the pocket of every smartphone user, who knows where the barcode will take us next?
By Cat Robinson