UBI EasyCoder 601 XP – Service Manual Ed. 1
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Chapter 8 Print Unit
8.6 Label Stop Sensor
Description
The label stop sensor (LSS) is used to control the paper feed and
consists of a sliding carriage on which two photoelectrical sensors
are fitted. Both sensors are identical and contain one light-emitting
diode and one light-sensitive receiver. The distance from the light
path between the two parts of the LSS to the dot line on the printhead
is 46.3 mm (1.82"). The sensors can be moved up to 50 mm (1.97")
out from the inner edge of the paper web by means of a screw
protruding through the lower outer gable of the print unit. The label
stop sensor is hidden inside the print mechanism and covered by
two black plastic guide plates, which can be removed for cleaning.
Working Principles
The label stop sensor serves a number of purposes, depending on
how the printer is set up in regard of media type:
Label (w gaps):
A beam of light is emitted from the upper sensor and received by the
lower sensor. The firmware detects the front of each label, i.e. when
the light is completely interrupted by the opaque label, as opposed
to the semi-transparent backing paper in the gaps between labels. If
no label has been detected during a paper feed corresponding to
more than 150% of the set label length (Setup\Media\Media
Size\Length), a “next-label-not-found” condition is assumed. If a
renewed print operation gives the same result, an “out-of-paper”
condition is assumed.
Ticket (w mark):
A beams of light is emitted from the lower sensor
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. The beam can
either be reflected back to the same sensor by the white paper, or be
absorbed by a black mark. The firmware detects when the
front
edge of a black mark passes the sensor, i.e. when light starts to be
absorbed. If no mark has been detected during a paper feed
corresponding to more than 150% of the set ticket length
(Setup\Media\Media Size\Length), a “next-label-not-found” con-
dition is assumed. If a renewed print operation gives the same result,
an “out-of-paper” condition is assumed.
Ticket (w gaps):
The light is emitted from the upper sensor and received by the lower
one. The light will either pass uninterrupted through a detection gap
in the web or be blocked by the non-transparent ticket. The
firmware detects the rear edges of detection gaps, i.e. when the light
starts being interrupted. If no ticket has been detected during a paper
feed corresponding to more than 150% of the set ticket length
(Setup\Media\Media Size\Length), a “next-label-not-found” con-
dition is assumed. If a renewed print operation gives the same result,
an “out-of-paper” condition is assumed.
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/. For detection of black marks on the top
of the paper, the cables from the two
sensors could be switched on the CPU
board.
