BARCODE

Barcode is method of automatic identification and data collection. The first patent for a bar code type product was issued to inventors Joseph Woodland and Bernard Silver on October 7, 1952. The Woodland and Silver bar code can be described as a "bull's eye" symbol, made up of a series of concentric circles.

In 1948, Bernard Silver was a graduate student at Drexel Institute of Technology in Philadelphia. A local food chain store owner had made an inquiry to the Drexel Institute asking about research into a method of automatically reading product information during checkout. Bernard Silver joined together with fellow graduate student Norman Joseph Woodland to work on a solution.

Bar code was first used commercially in 1966, however, it was soon realized that there would have to be some sort of industry standard set. By 1970, the Universal Grocery Products Identification Code or UGPIC was written by a company called Logicon Inc. The first company to produce bar code equipment for retail trade use (using UGPIC) was the American company Monarch Marking in 1970, and for industrial use, the British company Plessey Telecommunications was also first in 1970. UGPIC evolved into the U.P.C. symbol set or Universal Product Code, which is still used in the United States. George J. Laurer is considered the inventor of U.P.C. or Uniform Product Code, which was invented in 1973.

A barcode is an optical machine-readable representation of data. Originally, barcodes represented data in the widths (lines) and the spacings of parallel lines, and may be referred to as linear or 1D (1 dimensional) barcodes or symbologies. They also come in patterns of squares, dots, hexagons and other geometric patterns within images termed 2D (2 dimensional) matrix codes or symbologies.

The 2D systems use symbols other than bars, they are generally referred to as barcodes as well. Barcodes can be read by optical scanners called barcode readers, or scanned from an image by special software. The first use of barcodes was to label railroad cars, but they were not commercially successful until they were used to automate supermarket checkout systems, a task in which they have become almost universal. Their use has spread to many other roles as well, tasks that are generically referred to as Auto ID Data Capture (AIDC). Other systems are attempting to make inroads in the AIDC market, but the simplicity, universality and low cost of barcodes has limited the role of these other systems. It costs about half a United States cent (US$0.005) to implement a barcode while passive RFID still costs about $0.07 to $0.30 per tag.

The mapping between messages and barcodes is called a symbology. The specification of a symbology includes the encoding of the single digits/characters of the message as well as the start and stop markers into bars and space, the size of the quiet zone required to be before and after the barcode as well as the computation of a checksum. Linear symbologies can be classified mainly by two properties: Continuous vs. discrete: Characters in continuous symbologies usually abut, with one character ending with a space and the next beginning with a bar, or vice versa.

Characters in discrete symbologies begin and end with bars; the intercharacter space is ignored, as long as it is not wide enough to look like the code ends.Two-width vs. many-width: Bars and spaces in two-width symbologies are wide or narrow; how wide a wide bar is exactly has no significance as long as the symbology requirements for wide bars are adhered to (usually two to three times wider than a narrow bar). Bars and spaces in many-width symbologies are all multiples of a basic width called the module; most such codes use four widths of 1, 2, 3 and 4 modules. Some symbologies use interleaving. The first character is encoded using black bars of varying width. The second character is then encoded, by varying the width of the white spaces between these bars. Thus characters are encoded in pairs over the same section of the barcode. Interleaved 2 of 5 is an example of this. Barcodes, especially the UPC have slowly become an essential part of modern civilization. Their use is widespread, and the technology behind barcodes is constantly improving.

BARCODE