Barcode History

The barcode history start at began of 1948. With Bernard Silver, a graduate student at Drexel Institute of Technology in Philadelphia, the president of a local food chain asking one of the deans to undertake research to develop a system to automatically read product information during checkout. Silver told his friend Norman Joseph Woodland about the food chain president's request. The problem fascinated Woodland and he began to work on the problem. Resolving the issue start with perforate card like catalog system and management warehouse.

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Barcode Principle

All bar code scanners work on the same basic principle. The scanner shines light onto the bar code, and then reads the light and dark spaces reflected back into the lens. Scanners vary according to light source and scanning technology, as well as size and portability.

Barcode Encoding Rule

There are many different bar code symbologies, or languages. Each symbology has its own rules for encoding characters (e.g., letter, number, punctuation), printing, decoding requirements, and error checking.

Bar code symbologies differ both in the way they represent data and in the type of data they can encode: some encode numbers; others encode numbers, letters, and a few punctuation characters; still others offer encodation of the 128 or 256 ASCII character sets. Recently unveiled symbologies include options to encode characters in any language as well as specialized data types.

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Barcode Types

Linear barcodes

2D Barcodes

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EAN

The EAN-13 barcodes are used worldwide for marking retail goods. The less commonly used EAN-8 barcodes are used also for marking retail goods; however, they are usually reserved for smaller items, for example confectionery .

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UPC

The UPC encodes 12 decimal digits as SLLLLLLMRRRRRRE, where S (start) and E (end) are the bit pattern 101, M (middle) is the bit pattern 01010 (called guard bars), and each L (left) and R (right) are digits, each one represented by a seven-bit code. This is a total of 95 bits. The bit pattern for each numeral is designed to be as little like the others as possible, and to have no more than four 1s or 0s in order. Both are for reliability in scanning.

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Code 39

Code 39 (also known as "USS Code 39", "Code 3/9", "Code 3 of 9", "USD-3", "Alpha39", "Type 39") is a barcode symbology that can encode uppercase letters (A through Z), digits (0 through 9) and a handful of special characters like the $ sign. The barcode itself does not contain a check digit (in contrast to—for instance— Code 128 ), but it can be considered self-checking by some, on the grounds that a single erroneously interpreted bar cannot generate another valid character. Possibly the most serious drawback of Code 39 is its low data density: It requires more space to encode data in Code 39 than, for example, in Code 128. This means that very small goods cannot be labeled with a Code 39 based barcode. However, Code 39 is still widely used and can be decoded with virtually any barcode reader .

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Code128

Code 128 is a very high-density barcode symbology, used extensively world wide in shipping and packaging industries. GS1-128 (formerly known as UCC/EAN-128) is one of its variants. It is used for alphanumeric or numeric-only barcodes . It can encode all 128 characters of ASCII and is also capable of encoding two numbers into one character width, called double density. This feature is evidence of it being designed to reduce the amount of space the bar code occupies, to address the ever-increasing needs of item catalogs. Each printed character can have one of three different meanings, depending on which of three different character sets are employed. Code 128 is the major component of the labeling standard for GS1-128 (formerly known as UCC/EAN-128) , used as product identification for container and pallet levels of retail markets.

Interleaved 2-of-5 ( I2 of 5 )

Interleaved 2 of 5 is a continuous two-width barcode symbology encoding digits . It is used commercially on 135 film and on cartons of products, while the products inside are labeled with UPC or EAN . I2/5 encodes pairs of digits; the first digit is encoded in the five bars ("black lines"), while the second digit is encoded in the five spaces interleaved with them ("white lines").

Codabar

Codabar is a linear barcode symbology developed in 1972 by Pitney Bowes Corp. It is also known as Codeabar, Ames Code, NW-7, Monarch, Code 2 of 7, Rationalized Codabar, ANSI/AIM BC3-1995 or USD-4. Because Codabar is self-checking, most standards do not define a check digit . The variants of Codabar in commercial and public use will sometimes define a proprietary check digit. For instance in an all-numeric string, the check digit algorithm might double the odd digits, take modulo 9, sum the results with the even digits, and represent the total in modulo 10.

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