Motorola STB4278, Руководство пользователя, Страница: 40 / 418

Symbol LS4278 Product Reference Guide 2-6
Aiming
On a typical UPC 100% hold the scanner between contact and 19 inches from the symbol (see Decode Zone on page 2-11 ). When
scanning using a single-line scan mode, ensure the scan line crosses every bar and space of the symbol.
Figure 2-2. Acceptable and Incorrect Single-Line Aiming
When scanning using a multi-line scan mode, at least one scan line must cross every bar and space of the symbol.
Figure 2-3. Acceptable and Incorrect Multi-Line Aiming
Regardless of the scan mode, the scan line is smaller when the scanner is closer to the symbol and larger when it is farther from the
symbol. Scan symbols with smaller bars or elements (mil size) closer to the scanner, and those with larger bars or elements (mil size)
farther from the scanner.
Do not hold the scanner directly over the bar code. Laser light reflecting directly back into the scanner from the bar code is known as
specular reflection. This specular reflection can make decoding difficult.
Scan line lengths vary depending on the scan line width selected. A full scan line width is the default. Medium
and short scan line widths are useful for scanning menus or pick-lists.
For more information about scan line widths and scanning modes, see page 5-10 and page 5-11 , respectively.
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