Machine Description
Operating Instructions
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ITS6_135_Manual_EN.doc
4.6.13.1 Properties of print mark sensors
The so-called print mark sensors or bar sensors are used for synchronized
printing of continuously fed material, whereby the distance between the in-
dividual images to be printed has been established in advance, and is de-
fined by the rectangular print marks, the so-
called “bars,” which have been
applied to the printing substrate in advance by the manufacturer. Pre-
printed material is unsuitable if
…
… the print marks are smaller than 5 x 2 mm,
… the print marks have been applied at an angle or have fringed con-
tours,
… the gray-scale contrast between the print marks and the particular
background is too low,
… the print marks have the same color as or a similar color to the light
of the particular print mark sensor,
… other image elements are found between the print marks, which the
sensor could detect as a print mark.
A print mark sensor can only be moved perpendicular to the direction of
travel of the printing substrate, and should be positioned so that the print
marks pass directly through the sensor’s light beam – as seen from the di-
rection of travel.
When the sensor detects the leading edge of a print mark, it sends a signal
to the printer’s controls, which initiate the transfer of the next image as soon
as the printing substrate has covered the pre-set distance "leading edge of
print mark to beginning of printed image." This way, each image is placed
directly next to the print mark that triggered the image transfer through the
sensor signal. This also means that when printing with print marks, the dis-
tance between the leading edge of an image and the respective print mark
is always identical, and areas
in which a print mark is missing or isn’t de-
tected aren’t printed at all.
Information
Position the sensor so that as long as possible it detects print marks
that are aligned exactly perpendicular to the direction of travel.
Angled edges, for example on dots, cannot be precisely detected,
which can lead to inaccuracies in the positioning of images.
If a printer has two print mark sensors, only of them can be active at
a time. Both cannot be used at the same time.