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10 ALIGNMENT
Device is provided with a sensor for the use of alignment notch in order to handle:
•
roll of tickets with pre-printed fi elds and a fi xed length;
The alignment notch may be formed by
•
black mark printed on paper (see par.7.5);
All alignment sensor is a "refl ection" sensor: this kind of sensor emits a band of light and detects the quantity of light
refl ected to it. The presence of the notch is therefore detected by the amount of light that returns to the sensor, con-
sidering that the light is refl ected by the white paper and absorbed by the black mark.
The following paragraphs show how to correctly set the confi guration parameters of device in order to assure the
alignment.
10.1 Enable alignment
To guarantee the alignment, it is necessary to enable the parameter "Notch alignment" during the Setup procedure
(see chapter 5).
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 alignment" pa-
rameter is set to "Enabled" (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 of the alignment sensor driver so that it can be perform an optimal notch detection:
Autosetting Notch : OK
PWM Duty Cycle : 85.3%
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 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 Threshold"
value.
This graphic representation is useful to set the most suitable value to assign to the "Notch Threshold" parameter and
then to better identify the optimal threshold value which takes into account the variations of the signal and the small
oscillations around zero.
10. ALIGNMENT
KPM216HII 81
User manual
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