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Technical Specifications B–5
B.6 Bar Code Symbol Specifications
All bar code symbols should satisfy the appropriate AIM Uniform Symbology
Specification.
Background Substrate
The bar code symbol should be printed on material which is reflective and has a matte
(not glossy) finish. A background diffuse reflectance of at least 70% to 80% is desirable
for optimum contrast.
Ink Color and Type
The type of ink should be compatible with 660nm LEDs used in the scanner. The bar
code symbols inked bars should not exceed 10% reflectance at 660nm which is being
used for reading, whether printed with black ink or colored ink.
Voids and Specks
The code should be printed clearly, free of voids, specks, blemishes and lines which
could “fool” the scanner. Specks or blemishes in the white spaces, or false or missing
bar sections could be interpreted by the reading equipment as part of the code.
Generally, the width of such flaws is more serious than the height. Code symbols should
be rejected if these defects are present.
Definition
The bars in the bar code symbol should be well defined. Their edges should not be rough
or fuzzy, so that the bars and spaces have the proper widths intended for the bar code
symbology used. Since a scanner’s aperture and resolution are chosen to comply with
these widths, definition should be sharp and consistent.
Tolerance
The ratio of the widths of bars and spaces in a bar code symbol must conform to the
appropriate AIM bar code specifications and can cause problems if not correct
throughout the bar code. Problems can occur when bar edges are smeared or rough, or
when they exhibit voids.