Bar Code

Bar Code

A bar code is a code in a printed form which can be easily read by a machine connected to the computer. The information or data is encoded using the width of printed bars, the width of spaces between bars, and the relative positions of wide or narrow bars and spaces (i.e. a unique wide or narrow combination of black and white bars). You can easily see this kind of bar codes on all imported goods, journals and books. Almost every field use this technology for their products. These bar code are the most cost effective and least expensive way of encoding information since the bar code labels can be printed on plain paper, which the machine can easily read and encode the data or information.

 

Bar code symbologies are essentially alphabets in which different widths of bars and spaces are combined to form characters and ultimately, a message. Because there are many ways to arrange these bars and spaces (which are printed in a defined ratios), numerous symbologies are possible “Bar Codes” are graphical patterns whose principle function is to convey data, and “symbologies” are sets of rules that relate these patterns to their encoded message. About a dozen barcode symbologies are internationally standardised and in widespread use. An attempt has been made to broadly categorise barcode symbologies, then briefly identify those in common use and their main strengths.

Bar code designers have insisted that the symbologies be bi-directional that is the bar code message should be capable of being read either from the left to right or from right to left with no difference in performance. Many bar codes have the bars arranged vertically from top to bottom or vice versa. To accomplish this bi-directionality each symbology provides a separate start or stop character, in addition to the message characters. The start character is referred to as the unique character to the left and the stop character is the unique character to the right of the bar code.

One dimensional (1D) bar codes are constant from top to bottom, a line up of bars with varying widths and spacing like the ubiquitous Universal Product Code (UPC) symbols used in grocery stores. On other hand, 2D symbologies are two distinct flavours:

1. Stacked – 2D symbols are composed of multiple 1D rows and are fully decidable from multiple linear scan paths (e.g. laser scans) through the symbol in approximate alignment with its rows.

2. Matrix – 2D symbols are composed of a grid arrangement of light and dark modules, like a checkerboard, and require a 2D camera or image based reader. In general, 2D matrix symbols take up less than half the area of stacked symbols for the same data and image readers read all symbols in any orientation.

The UPC (Universal Product Code) was the first bar code symbology to be widely adopted by the grocery industry and formally established UPC as the standard bar code symbology to mark products.

Applications of BAR CODE

1. Asset management,

2. Access control,

3. Cataloguing,

4. Check IN/OUT,

5. Document tracking,

6. Finger print identification,

7. Item tracking,

8. Robotics,

9. Security,

10. Personal identification,

11. Production control and work in progress, etc.

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