Linx Printing Technologies Ltd

Other

Michael R Keeling

Hillar Weinberg

David J Langrick

A method is provided for adjusting the operating amplitude of a modulation signal which influences the separation of drops from an ink jet of an ink jet printer. The method includes (1) determining the phase relationship between the modulation signal and the instants when successive drops separate from the ink jet for a plurality of amplitudes of said modulation signal (2) identifying the amplitude of the modulation signal at a predetermined characteristic point in the function of the phase relationship with the amplitude from the magnitude of the change of the phase relationship with the change of the amplitude; and (3) selecting the operating amplitude for the modulation signal in accordance with the amplitude identified in step (2). An ink jet printer is also provided which has control means for identifying the predetermined point from the magnitude of change of the phase relationship between the modulation signal and the instants when successive drops separate from the ink jet with change in the amplitude of the modulation signal.

Modulation signal amplitude adjustment for an ink jet printer

An ink jet printer automatically adjusts the amplitude of the modulation signal applied to a transducer (159) to break the ink jet into droplets. Correct modulation amplitude is determined from changes in jet break-up length, as determined by changes in jet break-up length, as determined by changes in jet break-up phase relative to the modulation signal. The printer has interchangeable print heads (3), which may have different nozzle sizes. A calibration code, specifying the particular values of ink pressure, jet velocity and charge correction required for optimum performance of a particular print head (3), may be entered into control logic (93), which operates the printer accordingly. Most print head components are mounted on a mounting subtract (111), with all connections being made to the underside of the mounting subtract (111) and sealed with a potting compound, to avoid damage. Ink viscosity is controlled in response to ink pressure, which is in turn controlled in response to ink jet velocity. Thus all three parameters are maintained without the need for a viscosity meter. Ink jet velocity is sensed from signals induced by charged drops on spaced apart sensors (89, 91), the outputs from which are wired together and fed to a common comparator (105), which simplifies construction.

Ink jet printer with control

Fluid is applied in droplet form to a substrate by feeding the fluid to a nozzle so that the fluid issues from the nozzle as a single substantially coherent jet following a single jet flight path, causing the jet to break up into a series of substantially uniformly sized droplets, and applying a sufficiently large electrical charge to the fluid by means of a charge electrode so as to form mutually repellant droplets having flight paths which diverge from one another. The single jet path is directed into a catching device by which the fluid is caught and prevented from being applied to the substrate. The jet of fluid is broken up into a stream of substantially uniformly spaced droplets and the divergent stream of droplets is directed away from the catching device and allowed to reach the substrate so as to deposit fluid on the substrate.

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Cambridge, United Kingdom

Michael R Keeling