Technology

Technology

Barcode

Since their invention more than 50 years ago, bar codes have been enablers for accurate data capture, the rapid movement of goods, and all types of automation. Whether at the Point-of-Sale, in a hospital, or in a manufacturing environment these little black and white images deliver incredible value. 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. Barcode 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.  Barcodes in common use are covered by international standards. International standards also cover print quality measurements and equipment. Barcode technology standards define:

  • Rules for representing data in an optically readable format,
  • Rules and techniques for printing or marking,
  • Reading and decoding techniques, and
  • Rules for measuring the quality of printed/marked symbols

 

 

Linear Symbologies:
Barcodes in their most familiar format - a series of varying-width parallel bars and spaces - have been with us for over 25 years. These linear, or 1D (one dimensional as opposed to two dimensional bar codes) symbologies continue to be the most widely used optical recognition technology. Well over 100 encodation schemes or symbologies have been invented over the years, with roughly 20 reaching international standardization.
CODE 128

a very high-density barcode symbology, is currently used extensively world wide in shipping and packaging industries. The symbol can be as long as necessary to store the encoded data. It is designed to encode all 128 ASCII characters, and will use the least amount of space for data of 6 characters or more of any 1-D symbology.
THE UNIVERSAL PRODUCT CODE OR UPC BARCODE 
was the first bar code symbology widely adopted. Its birth is usually set at April 3, 1973, when the grocery industry formally established UPC as the standard bar code symbology for product marking. Foreign interest in UPC led to the adoption of the EAN code format, similar to UPC, in December 1976.
CODE 39 
pioneered by the defense and automotive industries, is an alphanumeric barcode. The symbol can be as long as necessary to store the encoded data. It is designed to encode 26 uppercase letters, 10 digits and 7 special characters. It can be extended to code all 128 ASCII characters by using a two character coding scheme.
INTERLEAVED 2-of-5 (ITF)
an all numeric code, was once used in the package delivery industry but replaced by Code 128. The symbol can be as long as necessary to store the encoded data. The code is a high density code that can hold up to 18 digits per inch when printed using a 7.5 mil X dimension. A check digit is optional.
CODABAR 
can encode the digits 0 through 9, six symbols (-:.$/+), and the start/stop characters A, B, C, D, E, *, N, or T. Codabar is used in libraries, blood banks, the overnight package delivery industry, and a variety of other information processing applications.
CODE 93 
offers higher information density for alphanumeric data than either Code 39 or Code 128. Code 93 is used primarily by Canada Post to encode supplementary delivery information. Every symbol includes two check characters.
CHANNEL CODE 
is a family of linear (one-dimensional) bar code symbols designed for encoding strings of 2 to 7 digits in the least symbol length possible.
TELEPEN 
is a bar code symbology designed in 1972 in the UK to express all 128 ASCII characters without using shift characters for code switching, unlike Code 128, while only using two different widths for bars and spaces. Unlike most linear bar codes that specify the encodings for each representable character, Telepen only defines four basic bar-space modules:
GS1 DATABAR
[formerly Reduced Space Symbology (RSS)] is a family of linear components of composite symbols. GS1 DataBar is widely used in the healthcare industry for both pharmaceuticals and medical/surgical products. GS1 DataBar has been identified to solve problems in the grocery industry where there had previously been no machine readable marking or there was inadequate information encoded. 
POSICODE
is a "position" based symbology, while most single width symbologies are presence/absence symbologies. Two variations of this code are allowed: PosiCode A, and PosiCode B. 
POSICODE A 
is optimal for applications where: 1) the mark width approaches the resolution of the reader, or 2) the accuracy of mark placement cannot be well controlled.
POSICODE B 
is optimal for applications where the mark width must be larger than the G dimension (between 1G and 2G), due to limitations of the marking technology. 

 

Matrix Symbologies:
Matrix symbologies offer higher data densities than stacked codes in most cases, as well as orientation-independent scanning. A matrix code is made up of a pattern of cells that can be square, hexagonal, or circular in shape. Data is encoded via the relative positions of these light and dark areas, and encoding schemes use error detection and correction techniques to improve reading reliability and enable reading of partially damaged symbols. Matrix codes are scaleable and well-suited both as small ID marks on products and as conveyor-scannable symbols on shipped packages.
DOT CODE
released by AIM in October 2009, consists of a rectangular, matrix symbologyspecificallydesigned to produce machine-readable coding with existing, in market high-speed industrial printing equipment. Because the symbols donot require continuous lines or touching elements, DotCode is ideally suited for high speed industrial ink jet and laser markingtechniques typically found in production lines for food and pharmaceutical products. 
DOT CODE A
is a two dimensional square matrix code constructed from dots. This symbology was designed for unique identification of objects in a relatively small area, or for direct marking by low precision marking technologies.
Applications include the identification of laboratory glassware and the marking of laundry. 
CODE ONE
is a two-dimensional matrix symbology containing dark and light square data modules and a finder pattern of parallel lines in the symbol's interior. A 2D imaging device such as a CCD camera is necessary to scan the symbology. Code One is used both for large data file encoding and small item marking applications.
MAXI CODE 
is a two-dimensional matrix symbology containing a fixed number of dark and light hexagonal modules. The symbol is specified to be a fixed size. MaxiCode has a bulls-eye finder pattern in the center of the symbol. A two-dimensional device such as a CCD camera is necessary to scan the symbology. MaxiCode is designed with two selectable levels of error correction capability. MaxiCode is used to encode address and customer specified data on shipping packages which are scanned on high-speed conveyors.
DATA MATRIX
is a two-dimensional matrix symbology containing dark and light square data modules. It has a finder pattern of two solid lines and two alternating dark and light lines on the perimeter of the symbol. A two-dimensional imaging device such as a CCD camera is necessary to scan the symbology. Data Matrix is used for small item marking applications using a wide variety of printing and marking technologies.
AZTEC CODE
is a two-dimensional matrix symbology containing dark and light square data modules. It has a finder pattern of concentric square rings centered on a single dark module located in the center of the symbol. A two-dimensional imaging device such as a CCD camera is necessary to scan the symbology. Aztec Code is used for small item marking applications using a wide variety of printing and marking technologies, and is also well suited for displays of cell phones and other mobile devices.
QR CODE
is a two-dimensional matrix symbology containing dark and light square data modules. It has position detection patterns on three of its four corners and features direct encodation of the Japanese Kana-Kanji character set. A two-dimensional imaging device such as a CCD camera is necessary to scan the symbology. Although initially used for tracking parts in vehicle manufacturing, QR Codes are now used in a much broader context, including both commercial tracking applications and convenience-oriented applications aimed at mobile phone users (known as mobile tagging).
DATASTRIP 2D
is a variable-size, variable-density two-dimensional symbology offering very high user data capacity at a required minimum level of error-correction and designed for printing on flat surfaces such as cards and to be read under controlled circumstances such as insertion readers. Datastrip 2D is ideal for identification documents such as driver's licenses and passports that require machine readable biometric data. It is designed to be easily produced by low-cost printing technologies such as ink jet, laser and plastic card printers.
GRID MATRIX
is a square, variable-sized, two-dimensional matrix symbology with unique dark- and light-framed "macromodules" that create a grid design that provides a robust finder pattern. The unique finder pattern ensures that readers can locate and orient the symbol even with significant symbol damage. Grid Matrix can encode any combination of data types in the same symbol. Grid Matrix is intended for broad use in both printed symbols and mobile phone display applications.


Stacked Symbologies
Stacked symbologies evolved as 1D codes -- Code 39 and Code 128 -- were stacked in horizontal layers to create the multi-row symbologies, Code 49and Code 16K, respectively. PDF417 followed in 1990 with added features that increased data capacity, improved data density, and strengthened reading reliability by a scanner. These features enabled decoding from scan paths that span multiple adjacent rows while incorporating error detection and correcting techniques. SuperCode, a stacked code that can break data into small packets and create various shaped symbols, is also a member of this group of 2D symbologies.
CODE 49
was developed by David Allais in 1987 at the Intermec Corporation to fill a need to pack a lot of information into a very small symbol. Labels can be printed by standard printing technologies.
CODE 16K
developed by Ted Williams in 1989 to provide a simple to print and decode multiple row symbology, is mainly used in the health care industry.. (The structure of 16K is based on Code 128). The code is a continuous, variable-length symbology that can encode complete ASCII 128-character set.
PDF417
is a two-dimensional, multi-row symbology designed to be scanned by laser scanners and linear CCD scanners and used to encode data files with hundreds or thousands of characters in a laser scannable symbol.  PDF417 is used in a variety of applications, primarily transport, identification cards, and inventory management.
SUPERCODE
is a packet bar code symbology, a variant of a multi-row symbology. There are precise rules for the horizontal placement of symbol characters in a packet, but greater freedom in placing packets vertically and horizontally than offered by a matrix of columns and rows in a multi-row symbology.


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