Briefly describe the code format and working principle of bar code.

Subject Peripheral and Interfacing
NU Year Set: 3.(b) Marks: 6 Year: 2017
What is a Bar Code?

A bar code is a binary coding system consisting of varying widths of vertical black lines (called bars) and white spaces that when read by an optical scanner can be converted into machine language. Bars and spaces are just one of many "elements" that make up a barcode.

Type of Code

UPC barcodes are used in the U.S. and Canada 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 shown in comparing the Interleaved 2of5 barcode 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
Ratio is important in deciding on the type of scanning device to read the code.  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 lower the bar code density.  The thinner the bar and spaces, the less space is required and the higher the bar code density.  Lower density bar codes are more reliably printed and more consistently read than higher density bar code.

Applications for Bar Codes

Bar codes are used in any applications where data needs to be automatically identified and captured efficiently and accurately in real-time for purposes of:

  • inventory control
  • asset tracking
  • product identification
  • patient information
  • warehouse picking and packing
  • and more…

Bar codes are used in many industries such as:

  • Healthcare
  • Packaging
  • Transport
  • Retail
  • apparel and textiles
  • automotive
  • government and defense,
  • and more…
Login to post your comment.