What element makes a bar code scanners?

Start and Stop Symbologies

Barcode symbols have 'start' and 'stop' characters at the beginning and ending.These characters enable barcode scanners read bidirectionally, decoding the data in the correct order. Bar codes sometimes have 'check digit' at the end which is determined according to an algorithm based on the preceding characters.

Quiet Zones

1/4" wide area next to the start and stop characters having no markings is called quiet zones. If the area is too short, the bar code symbol will not be read by scanner.

Interpretation Line

This is a line of human-readable characters which is located beneath the bar code.

Bar/Space Patterns

These are wide and narrow black bars and whites spaces present in the bar code.

Inter-Character Gap

In some bar codes,each character is printed independently of other characters and is not part of the encoded character.Therefore it is separated by an inter-character gap.

Code Density

Code density is number of data/message characters which can be represented per unit length of space. Four variables affect code density and are as follows:-

• Type of Code

  All bar codes have different structures. Some are able to encode more information per inch than others

• Ratio of Wide to Narrow Elements

  Ratio is important in deciding the type of scanning device to read the code. Changing the code density of a particular bar code is done 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. The X dimension dictates the width of all other bars and spaces, and ultimately the length of the bar code..