2D Barcode Symbologies
Wherever traditional linear bar codes act an index to a record in a database (e.g. part number, customer account number, etc.), two dimensional (2D) symbols can fulfil the same function while taking up significantly less space. In addition, 2D symbols can functions as the database itself, and therefore ensure complete portability for 2D labelled items.
2D symbols break from the traditional linear bar code symbologies such as Code 39 and UPC where most applications only need to encode between ten and twenty characters of information. In contrast, 2D bar code symbologies are able to encode up to several thousand characters of machine readable data. In effect, a portable database or portable data file can travel with the product and drive the decision making. 2D bar coding provides the freedom of movement for a database file allowing it to travel with a person or package, item, form, document, card or label. 2D bar coding provides a powerful communications capability without the need to access an external database. Furthermore, you can add 2D symbols to the documents and labels you are already printing.
By employing 2D symbols, more detailed information can be encoded and multiple linear bar code symbols can be reduced to a single symbol. When implemented properly, 2D symbologies can make industrial and commercial procedures faster, less costly, and more reliable by providing immediate access to the portable data file for that container. As an example, the manifest, bill of lading, and material safety data sheet could all be encoded into one 2D symbol. 2D symbols are much more resistant to damage than traditional linear symbols. By building error correction formulas into the 2D symbol, a significant portion of the surface area can be damaged and the information will still be intact. For example, some 2D symbols can lose up to a third of its surface and still be decoded.
Aside from PostNet bar codes used exclusively by the U.S. Postal Service to encode zip code information on letter mail, the most common 2D symbols employed today are PDF417, Data Matrix, and MaxiCode. The intellectual property rights (patents) for each of these codes are in the public domain eliminating the form of payment of royalties for use of this technology. 2D bar codes are currently represented in matrix symbologies or stacked-bar (multi-row).
Stacked bar codes are like a set of linear bar codes literally stacked on top of each other. PDF417 is the best example of a stacked-bar symbol and is the most common of all 2D symbols today. Stacked bar symbologies can be read by laser scanners, cameras, or CCDs.
Matrix bar codes are made up of a pattern of cells that can be square, hexagonal, or circular in shape and are similar in appearance to checkerboards. Matrix symbols must be read by a camera or CCD bar code scanner. These symbols offer higher data densities than stacked codes, at a ratio of about 3 or 4 to 1. Data Matrix and MaxiCode bar codes are the best examples of a matrix code.