Paper Supply; Paper Roll Holder - Hengstler XPM 80 Operating Manual

XPM 80™ Thermal Printer Family
Please note that the path signals are reversed between the connectors on Side A and
Side B. This is intentional, and is intended for those cases where a customer wishes
to connect the inputs from one paper path via one of the connectors, and the other
paper path via the other connector. With this wiring, the same customer wiring
harness may be used with the same pinout. Please note that, when so equipped,
both connectors may be used simultaneously, but only one connection for each input
or output may be used at once. For example, if a connection is made to the PPE
Sensor Signal Path 1 (A1) [pin 7] on Side A, a connection may not be made to PPE
Sensor Signal Path 1 (A1) [pin 2] on Side B.
Also, please note that the XPM 80™ does nothing more with the PPE and PWE
signals than report their status through the interface. For this reason, these inputs
are not limited to being used for PPE or PWE. Any one of them may be used to
detect the status of a door, for example, or any other status that can be sensed via a
microswitch or (in the case of the PPE inputs) an appropriate optical sensor.

6.4. Paper Supply

6.4.1. Paper Roll Holder

Based on our extensive experience in designing printers, we would urge you to
consider the following topics and implement your paper roll holder design with care.
Large Diameter Rolls: When using paper rolls over 100 mm in diameter, a "dancer
bar" should be considered. This usually takes the form of a spring-loaded arm under
which the paper is placed before feeding it into the printer. As the printer starts to
print, slack is taken up from the paper roll. This starts to lift the arm against the
spring, which puts force on the paper roll and starts it moving slowly. As more
printing takes place the roll gradually accelerates until it's up to printing speed.
Without the dancer bar, slack paper would be taken up until it was suddenly no longer
slack. Now the printer must accelerate a large, heavy paper roll from zero speed to
full print speed in essentially no time. This can cause the paper advance motor to
stall or the paper to slip against the platen, causing shortened characters until the
paper roll is up to speed.
Spindle Friction: Another important consideration is spindle friction. As a paper roll
rotates, it slides against the spindle that holds it, assuming a fixed spindle. This
friction will tend to impede the paper roll's free motion, and is dependent upon the
weight of the roll, the smoothness and material of the spindle, and the smoothness
and material of the paper core. When possible, especially with paper rolls over 100
mm in diameter, design the spindle so that it can rotate, greatly decreasing friction
and drag.
Catch Points: More paper jams and transport problems are caused by catch points
than any other issue. Make sure that the paper path is free of anything that can
interfere with free paper flow, especially any sharp edges or "pinch points" into which
the paper may stray and become caught.
Alignment: Any paper roll holder design must hold the paper square to the printer in
all planes. If the paper is angled in any way, it will enter the printer at an angle and
will be more likely to cause paper jams.
Part No. D 690 019 Mod. No. 4 051015 Eli1
HENGSTLER
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