Elements of a Barcode, continued...
Barcode density refers to the number of data, or message, characters that can be represented per unit length of space. Four variables affect code density: type of code, ratio of wide to narrow elements and the X dimension.
- Type of Code
UPC bar codes are used in the U.S. and Canada, while EAN and JAN symbols are used in Europe and Japan respectively. All bar codes have different structures. Some are able to encode more information per inch than others. An example is this comparison between the Interleaved 2of5 bar code with Code 3 of 9. The Interleaved 2of5 can encode more numeric information than the Code 3 of 9 in the same amount of space.
- Ratio of Wide to Narrow Elements
When deciding which scanner will accurately read a certain code, it is important to take into consideration the ratio of wide to narrow elements. Changing the code density of a particular bar code is accomplished by varying the ratio.
- X Dimension
The width of the narrowest bar or space is referred to as the X dimension, usually given in mils (thousandths of an inch). The X dimension dictates the width of all other bars and spaces, and ultimately the length of the bar code. The greater the X dimension, the more easily a bar code will scan. The smaller the width of the bar, the shorter the length of the symbol, the closer the tolerances are and the more difficult it is to print. The larger the width of the elements, the more space it takes to print the bar code; therefore, the bar code density is lower. The thinner the bar and spaces, the less space is required to print, and therefore the Bar code density is higher. Lower density bar codes are more reliable to print and easier to read than higher density bar codes.