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LS 1220 Product Reference Guide
Testing The Usable Scan Length Method
Due to the large variety of symbol sizes, densities, print quality, etc., there is no simple way
to calculate the optimum symbol distance. To ensure optimum performance use the Testing
The Usable Scan Length positioning method to maximize performance.
Determining the optimum distance between the scan engine and the symbol:
1.
Measure the maximum and minimum distances at which the symbols can be read.
2.
Check the near and far range on several symbols. If they are not reasonably
consistent there may be a printing quality problem that can degrade the
performance of your system. Symbol Technologies can provide advice on how to
improve your installation.
Note: Poor quality symbols (from bad printing, wear, or damage) may not decode
well when placed in the center of the depth of field (especially true of higher
density codes). The scan beam has a minimum width in the central area,
and when the scanner tries to read all the symbol imperfections in this area
it may end up with no decode. Therefore, after a preliminary spot is
determined using good quality symbols, several of lessor quality symbols
should be tested and the spot adjusted for the best overall symbol position.
3.
Locate the scanner so the symbol is near the middle of the near/far range.
4.
Center the symbol (left to right) in the scan line whenever possible.
5.
Position the symbol so that the scan line is as near as possible to perpendicular to
the bars and spaces in the symbol.
6.
Avoid specular reflection (glare) off the symbol by tilting the top or bottom of the
symbol away from the engine. The exact angle is not critical, but it must be large
enough so that if a mirror were inserted in the symbol location, the reflected scan
line would miss the front surface of the engine. For the maximum allowable angles
refer to the Skew, Pitch and Roll angles listed in each scan engine’s Technical
Specifications Table.
7.
If an additional window is to be placed between the scanner and the symbol, the
determination of optimum symbol location should be made with a representative
window in the desired window position. Review the sections of this chapter
concerning window quality, coatings and positioning.
8.
Give the scanner time to dwell on the symbol for several scans. When first enabled,
the scan engine may take two or three scans before it reaches maximum
performance. Enable the scan engine before the symbol is presented, if possible.
Summary of Contents for LS 1220
Page 2: ...LS 1220 Product Reference Guide ...
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Page 4: ...LS 1220 Product Reference Guide 70 12072 03 Revision A January 2003 ...
Page 23: ...1 8 LS 1220 Product Reference Guide Figure 1 3 LS 1220 Connector ...
Page 33: ...2 10 LS 1220 Product Reference Guide ...
Page 71: ...8 14 LS 1220 Product Reference Guide Figure 8 1 Hardware Handshaking ...
Page 97: ...9 6 LS 1220 Product Reference Guide Code Lengths cont d 1 2 3 4 5 6 7 8 9 0 CANCEL ...
Page 105: ...9 14 LS 1220 Product Reference Guide Prefix Suffix Values cont d 1 2 3 4 5 6 7 8 9 0 CANCEL ...
Page 108: ...9 17 Parameter Menus UPC Security Zone cont d 1 2 3 4 5 6 7 8 9 0 CANCEL ...
Page 120: ...9 29 Parameter Menus Intercharacter Delay cont d 1 2 3 4 5 6 7 8 9 0 CANCEL ...
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