Handheld barcode scanners are probably the most popular because of the flexibility of movement and the mobility they provide. A handheld barcode scanner can be used by an operator to locate the barcode and run the scanner over the barcode.
Desktop barcode scanners are also very popular and can be found in may retail outlets such as department stores and supermarkets where the item containing the barcode is located over the scanner in order to obtain the image. They can often be co-located with handheld scanners so operators can locate barcodes placed on awkward areas of a product.
A number of different techniques are used to obtain the image of the barcode:
One simple technique used by pen-type scanners is to run the scanner across the barcode in steady motion a photodiode measures the spacing between the dark bars and the light portion to produce an image. Laser scanners work in the same way except that they use a laser as the source of light.
Some scanners use a camera to capture a 2-dimensional image of the code and then process the image to produce the barcode.
Sometimes, a problem with barcode readers is the inhability to read a barcode that is not perfectly orientated on a flat surface, or it isn’t possible to manoeuvre the item holding the barcode into a suitable position. Some readers, such as those used in supermarkets use laser technology, but in such as way as to send out a serious of light beams in different directions to a pre-determined pattern, which enables the device to detect even awkward images that may not be on an even surface.
Barcode readers can have a number of interfaces to enable connection to a PC or storage device. Probably the most common interface is a USB interface which is available on most PCs and terminal devices today. The barcode reader can also receive its power from the terminating device, so that an external power source or batter power is not needed. Early barcode readers could use a standard keyboard port on a PC, with the barcode scanner emulating the keyboard so that characters could be displayed and stored on the PC. This was often referred to as a ‘Keyboard Wedge’.
Many barcode scanners can be operated on Wireless LANS or even PANs using IEEE802.11 or IEEE802.15 technology. Most of this type of barcode scanner will often require battery power and thus replacement or recharging of batteries is a frequent operation