Calibration - OEM VKP80III User Manual

10. ALIGNMENT

10.2 Calibration

The sensor calibration occurs automatically and consists in adjusting the quantity of light emitted to match the degree
of whiteness of the paper used and the degree of black of the mark printed on paper.
The device automatically performs the self-calibration during the Setup procedure only if the "Notch/B.Mark Position"
parameter is set to a value other than "Disabled" (see chapter 5).
When self-calibration starts, the device performs some paper feeds and then it prints the calibration result and the
value of the PWM duty-cicle (also expressed as a percentage) of the alignment sensor driver so that it can be perform
an optimal notch detection:
Autosetting Notch : OK
PWM Duty Cycle : 2,7V [82%]
The "Autosetting Notch" parameter indicates the result of the self-calibration procedure; OK will appear if it has been
successful, NOT OK will appear if the procedure has failed.
After the printing of the procedure result, the device offers the execution of the function of paper characterization
"Characterize Paper" and the change of the "Notch/B.Mark Threshold" parameter which represents the detection
threshold of the notch.
Choosing the "Yes" value for the "Characterize Paper" parameter, the device prints a graphic representation (see fol-
lowing fi gures) of the outgoing voltage of the alignment sensor (expressed as a percentage) and the "Notch/B.Mark
Threshold" value.
This graphic representation is useful to set the most suitable value to assign to the "Notch/B.Mark Threshold" param-
eter and then to better identify the optimal threshold value which takes into account the variations of the signal and
the small oscillations around zero.
The following fi gure shows an example of paper with the non-thermal paper printed with black marks: the outgoing
voltage is constant while passing the white paper between two notches and presents a peak at each black mark.
In this case, the optimal value for the "Notch/B.Mark Threshold" parameter is placed about half of the peak.
peak
"Notch/B.Mark
Threshold"
86 VKP80III
User Manual
NON-THERMAL SIDE
THERMAL SIDE