Custom Audio Electronics KPM180H, User Manual

Page: 90 / 152

The following igure shows an example of paper with the non-thermal paper printed with black marks and other graphics (for
example, a barcode): the outgoing voltage is constant while passing the white paper between two black marks, presents
a peak at each black mark and presents some “noise” at each barcode.
In this case, the optimal value for the “Black mark threshold” parameter is located about halfway between the peak value
and the maximum value of the “noise” (as shown in igure).
THERMAL SIDE
NON-THERMAL SIDE
Peak
“Black mark
threshold”
Noise
If the maximum value of “noise” read by the sensor is very close to the peak value, it might be diicult to place the value
of the “Black mark threshold” at an intermediate point. In these cases, it is mandatory that the portion of paper between
the point of printing end and the front of black mark is completely white (no graphics). In this way, the only next graphic
detected by the sensor for alignment after the printing end will be the black mark.
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