Monthly Archives: June 2015

barcodeBar codes are quite taken advantage of these days, but the truth is that they've helped us grow our businesses by leaps and bounds.  Not only businesses, but public records, libraries, and more all use bar codes in order to quickly sort and catalog all sorts of information.

Let's take a look back at the early days of the bar code, and appreciate how far we have come in terms of technology.

This article is quite amusing, in that it treats bar codes as some new alien technology.  However it should all be common knowledge nowadays.

Multifield Code

The advantage is that several items of information (P.O. box number, account number, document type and so on) can be incorporated in a single bar code. The catch is that someone has to tell the computer something about the document in order to get the label printed, so keystrokes cannot be totally eliminated.

While both labeling methods involve some additional effort and cost, the potential gains in document control are significant. Presorting is minimized or eliminated. More important, any document, once bar-coded, can be tracked easily from its arrival in the mail room to its final disposition.

No longer can documents get lost in the system. Document tracking pinpoints their location immediately, and even identifies documents delayed in processing.

The codes that make all this possible are nothing more than precise patterns of wide and narrow dark bars and light spaces that provide a machine-readable interpretation of an eye-readable value.

Numerous symbologies have come into use as bar code technology evolved, but today four are more widely used than the rest: The uniform product code (UPC), Codabar, interleaved two of five, and Code 39 (three of nine).

While each has advantages for certain applications, Code 39 is most commonly used for document applications because of its alphanumeric content and unlimited character length.

All symbologies include start and stop characters for scanning from either direction, and most have self-checking features that verify the accuracy of their interpretation.

Bar codes can be quite arbitrary. While other technologies such as optical character recognition (OCR) might "guess" at an imperfect character, bar code scanning will reflect it as a "no read."

"First try" reading depends heavily on the quality of the printed code. Contrast ratio, narrow and wide element width, code density, height to width ratio and carbon content all matter. Because of the self-checking feature, the misread rate is low. One government study set it at fewer than one in 3 million characters.

Devices for reading bar codes generally can be defined as either fixed-beam or moving-beam scanners. In fixed-beam devices such as wands or photo-diode scanners, a focused light beam passes over the bar code or vice versa, and the modulation of reflected light from the dark bars and light spaces generates a signal.