Bar Code Scanners

Often found at the checkout counter, laser scanners decipher information contained within bar codes, allowing a host computer to process data such as product names and costs.

Projecting a laser beam off a rotating prism or mirror, the device reads the bar code, noting the width of its bars and spaces. The beam is reflected from the bar code back to the scanner, where it is analyzed.

Software within the scanner or its host translates the information obtained from the bar code into data that the computer can recognize. Laser scanners can read bar codes through glass or from uneven surfaces at distances up to 30 inches.

Bar codes are composed of bars and spaces of varying widths. Each bar-space combination creates a character that, when read with other bar-space combinations, forms a message. Although the messages contained within each bar code vary, their structures are similar.

All bar codes begin and end with specific characters that indicate which direction the scanner should organize the information. Though the character on the left is traditionally considered the start, the bar code can be read from either direction.

A quiet zone, which contains no data, precedes the start character and follows the stop character, noting when the scanner should begin to read the code and when it should stop reading.

The most common bar code is the Universal Product Code, or UPC, which is made up of 12 digits.

Source: https://www.accurtone.com/faqs.html

Researched by CHRISTINE FREY/For The Times