Label Stop Sensor (Lss) - Intermec EasyCoder 501 Service Manual

Chapter 8 Print Unit
8.6 Label Stop Sensor
1 /. For detection of black marks on the
top of the paper, the cables from the
two sensors could be switched on the
CPU board.
50
The label stop/black mark sensor (LSS) consists of a sliding car-
riage on which two photoelectrical sensors are fi tted. Both sensors
are identical and contain one light-emitting diode and one light-
sensitive receiver. The sensors can be moved up to 50 mm (1.97
inches) out from the inner edge of the media. Note that the LSS in
the ribbon save print unit (see Chapter 10) has a different design,
but the principles of operation are the same for both types.
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. Three cases may occur:
• Non-transparent media will block the beam.
• Semi-transparent liner (backing paper) between labels will let
some of the light through.
• Absence of media lets the light pass uninterrupted.
The Intermec Fingerprint fi rmware detects the start of each label,
that is, when the condition switches from semi-transparent liner to
opaque label. If the light passes without any interruption for more
than 61 mm (2.4 inches) of media feed, an out-of-paper condition
is assumed.
Ticket (w mark)
Beams of light are emitted from the lower sensor
either be refl ected back to the same sensor by the white media, or
be absorbed by a black mark.
The Intermec Fingerprint fi rmware detects when the rear edge of
a black mark passes the sensor, that is, when light starts to be
refl ected after having being absorbed. If no light is refl ected back
within 61 mm (2.4 inches) of media feed, an out-of-paper condi-
tion is assumed.
Intermec EasyCoder 501 – Service Manual Ed. 7
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. The beam can