26 Introduction
2006792 Rev B – 200228
After the ink is mixed with makeup fluid in the Mixing Tank, a Pressure Pump delivers it to a
Hydraulic Manifold and out to the (two-way) Umbilical Tube. The Umbilical Tube carries the ink
to the Printhead. Inside the Printhead, ink is channeled to the Gun Body, which ejects the
pressurized ink out through its 60-micron orifice. An AC sine wave is delivered to two (brownish)
Piezo ceramic electric rings on the back of the Gun Body. These two rings have opposite
polarity. As a result, the sine wave causes the rings to move rapidly up and down in unison,
creating an ultrasonic vibration/oscillation. This vibrates the Gun Body, breaking the steady ink
stream into droplets (approximately 76,800 droplets per second). The amplitude of the electric
sine wave dictates where the ink stream breaks into droplets. That is, the higher the
voltage/amplitude, the earlier along the Charge Electrode Tunnel the ink jet breaks up, and,
conversely, the lower the voltage/amplitude, the further downstream the ink jet breaks up.
The ink jet needs to break up into droplets within the Charge Electrode Tunnel in order for the
Printhead to print properly. As the droplets pass through the Charge Electrode Tunnel, some
droplets are given a negative electric charge in an amount corresponding to the information
received from the JetStream software about the pattern of dots to be printed.
Once charged, the droplets pass a Phase Detector, which ensures that droplets are being
charged at the same rate as they are being produced.
The droplets then pass between two Deflector Plates. One plate is negatively charged, and the
other is positively charged. The negative Deflector Plate slightly repels the negatively charged
ink droplets, and the positive Deflector Plate attracts these droplets. The higher the negative
charge that a droplet has been assigned in the Charge Electrode Tunnel, the more the droplet
will be pulled toward the positive Deflector Plate and diverted out through the Printhead Orifice.
As these ejected droplets hit the passing print surface of the product, they land in a vertical
column, depending on the degree of charge that they were assigned.
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