Raster Graphics Inc.

Larry Capps

David Albertalli

Donald R Billet

Noel Schmidt

Paul Gregory

Gus A Adriancen

The present invention is generally directed to providing drop volume normalization of the ink jet nozzles in an ink jet printing operation to alleviate and/or eliminate banding effects due to imprecise placement of ink drops on the printed sheet and variations in the volume of drops produced by different ink jet nozzles of the print device. Exemplary embodiments relate to a method and apparatus for controlling a print device having at least one ink jet nozzle by adjusting an offset control of a power supply used to control drop volume of the at least one ink jet nozzle. In a print device configured with piezoelectric ink jet nozzles, the output drop volume of the nozzle can be controlled within a predetermined range by adjusting the voltage supplied to the ink jet nozzle. As those skilled in the art will appreciate, this offset control of drop volume will result in a change to output ink velocity as well. Accordingly, exemplary embodiments of the present invention further compensate a firing time of the at least one ink jet nozzle as a function of the offset control to account for a change in output ink velocity of the at least one ink jet nozzle.

Method and apparatus for drop volume normalization in an ink jet

Printer heads are precision mounted relative to a plate on a printer carriage by assembling a plurality of identical printer head assemblies, each of the printer head assemblies including a printer head precision mounted to a printer head carrier, each of the printer head carriers having at least three alignment points. Openings are provided in a plate in precise locations corresponding to desired locations and orientations of the printer head assemblies on the plate. The openings each have at least three alignment points corresponding to the three alignment points on each of the printer head carriers. The printer head assemblies are positioned in corresponding ones of the openings and a force is applied against the printer head assemblies, such as by springs mounted on the plate, to cause the at least three alignment points on the printer head carriers to contact respective ones of the at least three alignment points in the corresponding ones of the openings. A printer head carriage having printer heads precision mounted to a plate is also disclosed.

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San Jose, CA, United States of America

Larry Capps