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Laser Scanners
Laser scanning is in widespread
use among a variety of applications
and integrated in hand held laser
guns,
projection or fixed scanners used in conveyor systems,
and in-counter scanners as seen in many supermarkets.
Laser scanners project a beam of energy off an oscillating
mirror or rotating prism and generate what appears
to be a red scan line. An omnidirectional projection
scanner creates a pattern or raster of red scan lines.
In reality, the scan line(s) is a laser spot rapidly
moving across at 30 or 40 times per second. Laser scanning
is ÒautomaticÓ in a sense that it generates multiple
scans activated either by sensing an object that is
placed in front of the scanner (known as autosense)
or by simply pulling a trigger. In comparison, a wand
must be moved manually across a bar code by hand and
thus is a manual scanning device.
One of the newest technologies regarding laser
scanning is ÒFuzzy Logic.Ó Fuzzy logic technology applies
artificial intelligence to reading poorly printed bar
codes and is ideal for low-contrast, high density bar
codes. Fuzzy logic offers the highest level of performance
and best first-time read rate across a range of bar
code qualities including harsh environments and rugged
operating conditions.
Projection scanners are commonly used in material
movement configurations. Both tabletop and fixed mount
projection scanners are popular units at many checkout
counters and conveyors systems respectively. Grocery
store clerks move items across tabletop scanners almost
as fast as it takes to remove the items from a cart
alone. Likewise conveyor systems scan at a much higher
rates than anyone is able to without making mistakes.
Laser technology is very popular in the United
States primarily due to patent grants. Only a hand
full of companies hold the central patents in this
technology preventing further domestic and foreign
competition. CCD technology is more popular among other
countries because of this legal issue.
Every laser scanner has a depth of field. The
depth of field is the range between the minimum and
maximum distance in which a laser scanner can successfully
read a particular bar code, and it is directly related
to the density of the bar code. For example, the higher
the density of the bar code, the closer the laser has
to be to read a symbol. Likewise, the lower the density
of the bar code, the farther away the laser has to
be to read a symbol. There will be some overlap between
the range of various bar codes, but as a general rule,
the user must keep this is mind when scanning. In regards
to bar coding, some common problems may exist with
the set up. The table on the next page outlines some
of these problems and the appropriate step(s) to take.
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