Code Reader 1200 Instrukcja Instalacji Pobierz pdf (Strona 33)

INSTALLATION

2.4.3 Picket-Fence Applications

In Picket-Fence reading applications scanning is parallel to the code motion direction (Figure

12). This

makes decoding sensitive to blurring and to code resolution since the code

elements change between consecutive scans.

The number of scans performed on the code and therefore the decoding capability is

influenced by the following parameters:

 number of scans per second (320 scans/sec. max)

 line speed (code motion) see par. 2.4.1

 label

dimensions

 reading field width

NOTE

The reading field width for dynamic applications is reduced with respect to

the static reading field width (reading diagram).

At least 5 scans during the code passage should be allowed to ensure a successful read.

The number of effective scans performed by the reader in picket-fence is given by the

following formula:

SN = [((FW-LW)/LS)

SS] -2 Where: SN = number of effective scans

FW = reading field width (in mm)

LW = label width (in mm)

LS = label movement speed (in mm/s)

SS = scans per second

Figure 12 - "Picket-Fence" Reading

Example:

A 60 mm wide code moving in a point where the reading field is 160 mm wide at a 1000

mm/s line speed, the TC1200 (320 scans per sec.), performs:

[((160-60)/1000)

320] - 2 = 30 effective scans

Direction of code movement

at LS speed

Illuminator

TC1200

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 175 176

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Code Reader 1200 Instrukcja Instalacji Strona 33