Device description
Leuze electronic GmbH + Co. KG
BCL 308
i
28
4.4.2 Line scanner with oscillating mirror
The oscillating mirror deflects the scan line additionally to both sides across the scan direction at a
randomly adjustable oscillation frequency. In this way, the BCL 308
i
can also scan larger areas or spaces
for bar codes. The reading field height (and the scan line length useful for evaluation) depends on the
reading distance due to the optical opening angle of the oscillating mirror.
Areas of application of the line scanner with oscillating mirror
For line scanners with oscillating mirror, oscillation frequency, start/stop position etc. are adjustable. It is
used:
• when the position of the label is not fixed, e.g. on pallets – various labels can, thus, be detected at
various positions.
• when the bars of the bar code are printed perpendicular to the conveying direction ("picket fence
arrangement").
• when reading stationary objects.
• when a large reading field (reading window) has to be covered.
Figure 4.10: Deflection principle for the line scanner with oscillating mirror add-on
4.4.3 Raster scanner (raster line)
Multiple scan lines scan the label. Due to the optical opening angle, the reading field width is dependent
on the read distance. Provided the code is located in the reading field, it can be read during standstill. If
the code moves through the reading field, it is scanned by multiple scan lines.
The integrated code reconstruction technology permits twisting of the bar code (tilt angle) within certain
limits. These are dependent on the transport speed, the scanning rate of the scanner and the bar code
properties. In most cases, everywhere a line scanner is used, a raster scanner can be used.
Areas of application of the raster scanner:
The raster scanner is used:
• When the bars of the bar code are perpendicular to the conveying direction
(picket fence arrangement)
• With bar codes with low height displacement
• With very glossy bar codes
