Barcodes are Predominant Automatic Identification Technology
Bar code is the predominant automatic ID technology used to collect data about any person, place or thing. Its applications appear unlimited. It is used for item tracking, inventory control, time and attendance recording, monitoring work-in-process, quality control, check-in/check-out. Sortation, order entry, document tracking, controlling access to secured areas, shipping and receiving, warehousing, route management, point-of-sale operations and as patient-care ids from tracking medicinal usage to patient billing.
Bar code is not a system in itself. It is an extremely effective identification tool that provides accurate and timely support of the data requirements for sophisticated management systems. Bar code usage generally increases accuracy and productivity, creates cost savings and improves business operations.
Bar codes are a pattern of bars and spaces of varying widths that represent digits, letters or punctuation symbols to identify an item or regulate its movement. The way the bars and spaces are arranged is called a symbology, of which there are many. The Universal Product Code (U.P.C.) and its world-wide counterpart, The International Article Numbering Association (EAN), are extensively used in retail. Very popular in industrial, medical and government application is Code 39, an alphanumeric symbology with self-checking properties that offers a variable length and a high degree of data security. It is endorsed by several industry trade groups including the Automotive Industry Action Group (AIAG), Health Industry Business Communications Council (H.I.B.C.C.) and the U.S. Department of Defence. It is also used for identification of photofinishing envelopes, in heavy industrial applications, high speed sortation and for warehouse inventory handling. Code 128 is a code that can represent the entire ASCII character set and offers high density and high security. It is the basis for the international language known as Application Identifiers (AI). Code 128 is endorsed by the HIBCC and the Uniform Code Council (UCC). Two-dimensional or “stacked” symbologies (PDF417, Codablock, 16K and Code 49, etc.) offer high-density data encodation in a fixed-width format with rows of bar codes stacked on top of one another. In addition, there are matrix codes such as Vericode, DataMatrix, Code 1 and Maxicode, which also provide high-density data storage.
In use, a symbol is illuminated by an infrared or visible light source; dark bars absorb the light and spaces reflect it back into the scanner. A scanner transforms the light fluctuations into electrical impulses which mimic the bars and space pattern in the bar code. A decoder uses mathematical algorithms to translate the electrical impulses into a binary code and transmit the encoded data message to a PC, controller or host computer system. The decoder may be integrated with or external to the scanner. Scanners are visible and infrared light-emitting diode (LED) or solid-state laser diode (visible or infrared) light to read the symbol. Some require contact with the code or label; others read from distances up to several feet. Some are stationary; others are hand-held.
Most have moving or fixed beams to illuminate the symbol; some are charge-couple devices (CCD) which photographically “see” the whole symbol at once. Two-dimension CCD readers are used to read matrix symbologies. Each type of scanner provides its own benefits, but to gain the most from a bar code system, the scanner should matched to the application.
Bar codes can be printed directly on items to be scanned or on labels either manufactured by an outside supplier or printed on site. Popular on-site (in-house) printing technologies include: dot-matrix and other impact methods, thermal and thermal-transfer, ink-jet and electrophotography (laser printing). Popular off-site printing technologies for pre-printed labels include flexographic, laser etching, offset lithography, photo-composition, ion composition and electrophotography. Each technique has its own benefits for specific applications. Because a high first-time read rate is important for successful scanning, adequate print quality, as defined by American National Standard ANSI X3.182, is vital. Also important to a successful bar code system is the training of operators.
All bar codes have several similar components. They all have a clear space, called a quiet zone, before and after the symbol. Specific start and stop patterns indicate the beginning and ending of the symbol. Check characters, mandatorying some codes, allow a mathematical check which ensures the accuracy of the decoded information. Bar codes also frequently contain data or application identifiers-code prefixed that identify the meaning or intended use of the data that follows. This is important when bar codes are used between companies and industries or when there is the possibility of confusing the data in different symbols.
Verifying a bar code’s conformance to specifications before it enters the system flow is essential. Such verification is achieved with readily available verification or analyzer-type equipment (bar code verifier).