Rockwell Automation 2755-L7, -L9 Scanners - Manual (Page 43)

Glossary
G–5
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.
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 step ladder orientation
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.