Abstract: A combined deflection electrode and phase sensor electrode for a deflection type ink jet printer is made up of a ceramic support plate 19, a conductive layer 21 acting as the deflection electrode, layers of insulator 25 covering the conductive layer 21, and a patch of conductive material on the layers of insulator 25 to provide a phase sensor electrode 29 (Alternative constructions are also disclosed). A time of flight sensor electrode 31 may also be provided in the same way. The layers of insulator 25 prevent the sensor electrodes 29, 31 from being electrically connected, by splashes of conductive ink, to the deflection electrode provided by the conductive layer 21. The sensor electrodes 29,31 can have a larger sensing area than separately provided electrodes, allowing them to be further from the ink jet and thereby easing alignment requirements.

Abstract: A combined deflection electrode and phase sensor electrode for a deflection type ink jet printer is made up of a ceramic support plate 19, a conductive layer 21 acting as the deflection electrode, layers of insulator 25 covering the conductive layer 21, and a patch of conductive material on the layers of insulator 25 to provide a phase sensor electrode 29 (Alternative constructions are also disclosed). A time of flight sensor electrode 31 may also be provided in the same way. The layers of insulator 25 prevent the sensor electrodes 29, 31 from being electrically connected, by splashes of conductive ink, to the deflection electrode provided by the conductive layer 21. The sensor electrodes 29, 31 can have a larger sensing area than separately provided electrodes, allowing them to be further from the ink jet and thereby easing alignment requirements.

Abstract: A combined deflection electrode and phase sensor electrode for a deflection type ink jet printer is made up of a ceramic support plate 19, a conductive layer 21 acting as the deflection electrode, layers of insulator 25 covering the conductive layer 21, and a patch of conductive material on the layers of insulator 25 to provide a phase sensor electrode 29 (Alternative constructions are also disclosed). A time of flight sensor electrode 31 may also be provided in the same way. The layers of insulator 25 prevent the sensor electrodes 29, 31 from being electrically connected, by splashes of conductive ink, to the deflection electrode provided by the conductive layer 21. The sensor electrodes 29, 31 can have a larger sensing area than separately provided electrodes, allowing them to be further from the ink jet and thereby easing alignment requirements.

Abstract: 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).

Abstract: 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.

Abstract: A deflection arrangement for deflecting charged particles, e.g. ink drops in an ink jet printer, is arranged so that the potential dropped across an air gap between deflection electrodes varies with position along the air gap. This may be achieved by providing a varying thickness of dielectric material 31 on one deflection electrode 29, extending towards the other deflection electrode 27. Preferably, the width of the air gap varies to follow the fanning out of the paths of differently deflected particles (e.g. ink drops), and the variation in the potential across the air gap allows advantage to be taken of the fact that the dielectric strength (breakdown field strength) of air varies with the width of the air gap.