Videojet Systems International, Inc.

Bruce Ortquist

Robert I Keur

Timothy Braun

Printing distortions caused by ink stream/charge tunnel misalignment, charge tunnel mis-dimensioning or a variation in drop spacing or changes in ink resistivity are corrected by measuring the actual induction co-efficients for a particular printer. For this purpose, charge sensors located along the ink stream or adjacent the ink catcher detect induced charges from which the induction co-efficients are calculated by a programmable controller. These co-efficients are used to adjust the charge tunnel voltages to reduce or eliminate printing distortion.

Method and apparatus for correcting printing distortions in an ink jet

A method and apparatus are disclosed in which deflection and print speed are controlled by varying the nozzle drive frequency to increase or decrease drop velocity thereby to control drop deflection. The variation is done in a manner to maintain the ratio .lambda./d and drop size substantially constant. By altering the drop velocity the transit time of the drops through the high voltage deflection field is changed, permitting increased or decreased deflection. The system includes a pressure controller, a velocity sensor, a variable frequency nozzle drive and a processor. Calculations and operations are performed by the processor, based on the size of an operator selected image.

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Upper Arlington, OH, United States of America

Bruce Ortquist