Videojet Technologies Inc.

Videojet Systems International, Inc.

Andrew Earl Fickling

Dilip K Shrivastava

Michael J Rybicki

Henry F George

Certain embodiments provide a system and method for auto-threshold adjustment using a continuous ink jet printer. An embodiment of a system includes a nozzle for producing ink drops from an ink stream, a sensor positioned with respect to the nozzle for measuring charge from the ink drops to generate a charge signal, a peak detector for detecting peaks in the charge signal, and a threshold storage device for adjusting the threshold based on a number of detected peaks. In an embodiment, the threshold storage device stores the threshold. The threshold storage device may be a digital potentiometer, for example. The system may also include a comparator comparing the charge signal to the threshold. The comparator may select between the threshold and a standard reference signal to compare to the charge signal.

System and method for auto-threshold adjustment for phasing

An continuous ink jet printer projects a stream of evenly spaced ink drops toward a substrate and controls placement of the ink drops on the substrate by selectively charging the individual ink drops and passing the charged ink drops through an electric field to control placement of said charged ink drops on a substrate. The printer may be used to print either single or multiple lines of print in a single stroke. A stroke consists of a single column from all lines and can have adjacent drops printed in alternating lines to reduce drop interaction. Each line of print in the stroke having N virtual print positions, at least some of which are being divided into pairs of adjacent positions. Each pair of adjacent positions has a first print position and a second print position. The printer includes a controller having a plurality of first and second look-up tables, each of which is associated with a different one of said pairs of adjacent print positions. Each of the look-up tables contains a plurality of charge values which correspond to the charge to be applied to a print drop in one of the first or second print positions, respectively, as a function of the charges of each of a predetermined number of drops that are proximate to the print drop in the drop stream. The adjacent drops may include a predetermined number of history drops that precede the print drop in the stream and a predetermined number of future drops that follow the print drop in the stream. The controller determines the charge to be applied to drops and produces a control signal responsive thereto by (1) retrieving a charge value from one of the first look-up tables if the drop is to be printed in one of the first print positions, or (2) retrieving a charge value from one of the second look-up tables if the drop is to be printed in one of the second print drop positions. A charging tunnel receives the control signal from the controller and charges the drops to the determined charges in response thereto.

Printing method for continuous ink jet printer

A segmented charge tunnel for ink jet printing having a plurality of individual segments is utilized to sequentially apply charges to a droplet stream. Precise location of the stream break-off point within the tunnel is accomplished by identifying which one of the segments of the charge tunnel is associated with the detection of a maximum charge by a downstream sensor. Precise determinations of the distance between the break-off point and the detection downstream permits accurate droplet flight time measurement to allow ink composition and spacing to be controlled.

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Mt. Prospect, IL, United States of America

Andrew Earl Fickling