Hardware Technologies |
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| DOD
Large Character Printing |
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The method of controlling ink jet droplets can vary, but the
explosively popular drop-on-demand (DOD) technology is what
most people are familiar with. Ink is delivered to the printhead
from either a pressurized container of ink or ink pump. The
ink passes through a fine tolerance filter to trap any dirt
particles which may have been introduced into the ink. After
passing through the filter, the ink is distributed to each valve
or plunger in the printhead. One of two technologies is typically
used – valve or plunger. |
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Valve technology is most common. Ink is distributed by a manifold
to each individual solenoid valve (Lee valve technology). Each
valve is controlled by a high speed, timed electrical pulse.
As the valve opens and closes, a small, carefully measured drop
of ink is delivered through a small tube, out the nozzle and
onto the product substrate. There is a valve and nozzle for
each vertical dot that prints. (For example, a seven-dot head
has seven valves and seven nozzles.) |
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Many common printers utilize valve technology, including most
systems manufactured by Marsh, Diagraph, Loveshaw and others.
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Plunger technology simplifies the ink delivery system within
the printhead. Ink is delivered into a reservoir in the printhead.
Spring-loaded plungers inside the pressurized reservoir cover
exit holes. hese plungers are controlled by high speed, timed
electrical pulses which cause them to draw back momentarily,
allowing a small droplet of ink to escape through the nozzle
and onto the product substrate. |
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Manufacturers utilizing this technology include Leader. |
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| Hi-Resolution
Printing |
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Recent developments in ink jet technology include the high-resolution
printheads developed by Xaar Corporation and Trident International,
Inc. The printheads use proprietary piezo-electric technology
to produce print resolutions up to 200 dpi. Piezo-electric
is an ink jet technology that generates extremely small ink
jet droplets by variably expanding, or pulsing, a piezo-electric
crystal within
a jet. |
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Finer droplets mean higher resolution capabilities than currently
available from other ink jet technologies. The printhead is
commonly used for printing bar codes and high resolution graphics.
Trident and Xaar have current OEM agreements with several of
the leading ink jet printing manufacturers. |
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Examples of machines using the Trident printhead include those
manufactured by Leader, Marsh, Diagraph and others. |
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| CIJ
Small Character Printing |
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Continuous ink jet printing uses a slightly different technology.
With this printing method, ink jet droplets are constantly emitted,
but an electrical field and deflection plate control which droplets
are allowed to reach the receiving media. Unused ink
droplets are deflected into a recycling reservoir, mixed with
make-up fluids and distributed through the system again. |
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Videojet, Domino, Imaje and Linx small character printers are
examples of CIJ small character printing equipment. |
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