3-6
SE-923 Scan Engine Integration Guide
The decode zone is a function of various symbol characteristics including density, print
contrast, wide-to-narrow ratio, and edge acuity. Width of decode zone at any given distance
must be considered when designing a system.
Usable scan length is calculated as follows (see Figure 3-3):
L = 1.8 x (D+d) x Tan (A/2)
Where:
D = Distance (in inches) from the front edge of the housing to the bar code.
d = The housing’s internal optical path from the edge of the housing to the front
of the scanner.
A = Scan angle in degrees (53°).
So:
L = 1.8 x (D+d) x Tan 26.5°
Note:
Usable scan length determined by above formula, or 90% of the
visible scan line at any working distance.
The calculation given above is based on good quality symbols in the center of the working
range and length of bar code.
Figure 3-3. Usable Scan Length Diagram
SE 923
Scan Engine
Housing
d
D
A
Bar
Code
Содержание SE 923
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