Understanding Bar Code and Verifier Technology

By: Archibald Rockwealth

Bar codes have a specific standard for printing. Each bar code such as a UPC or an interleaved 2 of 5 "case code" has a specified tolerance on the printing widths of the individual bars and spacing in between the bars. Bar code verifiers were designed to measure the pass fail characteristics of the barcode and determine if the barcode is up to spec.

The difficulty with traditional verifier technology is that the scanning experience known by the end user does not necessarily correlate with the results of the verifier. For some reason, many of the bar codes that failed inspection, many of them were actually very easily read by the simple grocery store scanners. But on the other side of the coin, some bar codes that passed inspection were unable to be read by the same scanner. The difficulty came out of the barcode verification method not being commensurate with the way that real bar code scanners work.

Traditional verification is based on the comparison of printed bar widths to the published tolerance levels. If the bar code is within these levels, it passes inspection. Because of the electronic means to determine if the bar code was within acceptable levels, the tighter than necessary control threw out many passable bar codes. The verification methods simply look at the width of the bars and the spacing in between. Defects within the printed code will still pass inspection.

ANSI bar code verifier conformation has established a standard for bar code reading. The new standard is such that the bar code print quality is measured in accordance to the actual function of bar code scanners. Verifiers coming with the ANSI standard are relied upon by suppliers and customers. This ensures a standard across all levels and no confusion is present in the bar code scanners. This allows allow people on both the manufacturing and receiving end to expedite and process orders and shipments much faster. The ANSI standard in bar code verification also makes sure that there are no defects in the bar code that the traditional verification methods could have missed.

The quality guideline for barcode scanners was published in 1990 and established a procedure for measuring bar code quality. The methodology established eight separate codes for bar code scanning. The output of the ANSI method produces a number and letter grade for the bar code scanner and determines the quality of the bar code. A letter grade of "C" or better should scan on any machine and be readable without any kind of hitch. Some manufacturers request a bar code standard of at least a "B" or better with the printing of each bar code. This puts a strain on the manufacturer of the barcode, but with the modern bar code verification techniques, the bar code is guaranteed to be readable by any scanner and business can progress. The old style of bar code verification would not permit such leniency in bar codes and would either fail the majority of good bar codes or pass bar codes which are useable.

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