Optical bar code readers

This method uses a number of bars or line of varying thickness and spacing between them, to indicate the desired information. Barcodes are used on most grocery items, cosmetics, paperback novels, etc. An optical bar reader can read such bars and convert them into electrical pulses to be processed by a computer. The most commonly used barcode is universal product code (UPC ). The UPC code uses a series of vertical bars of varying widths. These bars are detected as ten digits. The first five digits identifies the supplier or manufacturer of the item. The second five digits identifies individual product number. The code also contain a check digit, to ensure that the information read is correct or not.