Symbol LS 6800, Руководство пользователя, Страница: 28 / 249

3-8
LS 6800 Product Reference Guide
Figure 3-9. Moving Scan Pattern Upward and Downward on “Tall” PDF Symbol
t
The scan beam does not have to be perfectly parallel with the top and bottom of the
symbol (up to a 4
o
tilt works).
Specular Reflection
When laser beams reflect
directly
back into the scanner from the bar code, they can “blind”
the scanner and make decoding difficult. This is specular reflection.
To avoid this, scan the bar code at a slight angle so that the beam does not bounce directly
back. But don’t scan at too oblique an angle; the scanner needs to collect scattered reflections
from the scan to make a successful decode. Practice shows what tolerances to work within.
Figure 3-10. Avoiding Specular Reflection
Specular reflection:
reflected beam interferes. No specular reflection.
Decode can occur.
Bar Code
Bar Code
Tilt Back At Slight Angle (Up to 30
o
)