Bar Coding and Radio Frequency Identification

AuthorR. Inman

Page 35

A barcode is a series of parallel black bars and white spaces, both of varying widths. Bars and spaces together are called elements. Different combinations of the bars and spaces represent different characters, such as numbers or letters. Each combination or sequence of bars and spaces is a code that can be translated into information such as price, product type, place of manufacture, or origin of shipment.

Barcodes are simple to use, accurate, and quick. Almost everyone is familiar with their use in retail establishments. They are also often used in ware-houses and manufacturing for selecting items from storage, receiving goods, and shipping.

The FDA requires that a product's national drug code be placed on the container label and outer wrapper on most prescription drugs and about 70 percent of over-the-counter drugs and on blood and blood components intended for transfusion. The U.S. Food and Drug Administration (FDA) estimates that this will prevent nearly 500,000 adverse events and blood transfusion errors and save $98 billion in reduced healthcare costs over a two year period.


The barcode itself does not actually contain detailed information. The barcode simply provides a reference number that cues a computer to access information. A barcode reader is required to read a barcode. Barcode readers may be fixed, portable batch, or portable RF. Fixed readers are attached to a host computer and terminal, and transmit one item at a time as the data is scanned. Battery-powered portable batch readers store data into memory for batch transfer into a host computer at a later time. The portable RF reader can transmit data in real-time, on-line.


The basic reader consists of a scanner and a decoder. Scanners capture the image of the barcode, and the decoder takes the digitized bar space patterns, decodes them, and transmits the decoded data to the computer.

There are several types of scanners. Laser scanners use a single spot of light to sweep across the barcode in a linear fashion. CCD scanners use an LED array with thousands of light detectors; the entire barcode image is captured and then transmitted. Automatic scanners are in a fixed position and read barcodes as they go by on a conveyor. Handheld scanners, such as wands, are portable and may be carried from place to place, as in a warehouse.

When a scanner is passed over the barcode, the dark bars absorb the scanner's light while the light spaces reflect it. A photocell detector receives the reflected light and converts it into an electrical signal. A low electrical signal is created for the reflected light and a high electrical signal is created for the dark bars. The width of the element determines the duration of the electrical signal. The decoder then decodes the signal into the characters represented by the barcode and passes it to a computer in traditional data format.


There are different types of barcodes. Some bar-codes are entirely numeric, whereas others have numeric and alphabetic characters. The type used is dependent upon the...

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