Allen-Bradley Series B

Glossary
G–7
print quality
The complete analysis of a printed
symbol with regard to reflectance
properties as well as bar and space
resolution with regard to symbol
specification. The inter–relationship
of printed material and imprinted
material that affects the optimum
performance of the scanner.
proximity sensor
A method of object detection in
which the source and detector are
located on the same side; the detector
senses energy from the source which
is bounce back by the object being
detected.
Q
quiet zone, quiet area
An area preceding and following a
bar code symbol that contains no
printing.
R
raster scanner
Also available as an optional raster
assembly. Raster scanners are
similar to standard scanners. The
beam still travels from left to right,
but it now does so in a sinusoidal, or
top to bottom, pattern. This allows
the scanner to see different scan
paths so if a bar is deformed or
soiled in one place it may still be
read due to the sinusoidal sweep of
the beam.
read
A successful scan of a bar code
symbol.
reflectance
The amount of light returned from an
illuminated surface.
reflectance, absolute
The ratio of the total reflectance by a
document to the total light incident
on the document.
reflectance, diffuse
Reflected light whose angle of
reflection varies from the angle of
incidence of the illuminating light;
such as reflection from a non–glossy
surface.
reflectance, specular
Reflected light whose angle of
reflection is equal, or nearly equal, to
the angle of incidence of the
illuminating light, as in reflection
from a mirror.
reflex
A method of object detection in
which the source and detector are
located on the same side; a
retroreflector on the far side returns
the energy from the source to the
detector.
reject
See no–read, non–read, non–scan.
resolution
1) The measure of the ability of a lens, a
photographic material or a photographic
system to distinguish detail under certain
specific conditions. 2) The dimension
of the smallest element which can be
printed employing a particular technique.
3) The narrowest element dimension
which can be distinguished by a
particular reading device.
retro
See retroreflective.
retroreflective
Characteristic of material causing it
to reflect light back to its source
regardless of angle of incidence.