Glossary
G–4
H
hand–held scanner
Refers to any scanning device that
must be held over the bar code
symbol.
height–of–scan
The maximum vertical scanning
dimension of a moving beam scanner
at a specific distance from the face of
the scanner.
helium neon laser
The type of laser most commonly
used in bar code scanners. Because
the laser beam is bright red, bars
must not be printed with red ink
since they would be indistinguishable
from the background.
horizontal bar code (Picket Fence)
A bar code or symbol presented in
such a manner that its overall length
dimension is parallel to the horizon.
The bars look like a picket fence.
I
incandescent light source
Intense white light used to illuminate
an object as it passes under a CCD
camera.
intercharacter gap
The space between two adjacent bar
code characters. For example, the
white space between two characters
in AIM USS–39.
interleaved bar code
A bar code in which characters are
paired together using bars to
represent the first character and
spaces to represent the second; as in
USS–I 2/5
K
key mark or trigger
A code bit(s) that provides the
scanner with the instruction that the
code is in a position to be read; used
in some fixed beam readers.
L
ladder orientation
See vertical bar code.
laser scanner
An optical bar code reading device
using a low energy laser light beam
as the source of illumination.
Light Emitting Diode (LED)
A semiconductor diode generally
made from gallium arsenide, that can
serve as a near infrared light source
when voltage is applied continuously
or in pulses. LED’s have extremely
long lifetimes when properly
operated; being solid–state, they are
very resistant to shock and vibration.
light operated
Condition in which the control
operates when the light beam in
uninterrupted.
M
mis–encodation
When the characters which were to
be represented in symbol form are
not correctly encoded. Example:
desired number is 1,2, 3, 4; the
encoded number is 1, 2, 5, 4.
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