Abstract: A filter material has a layer of porous material and a plurality of structures disposed on a surface of the layer, where each of the structures has a re-entrant geometry. The plurality of structures may be a plurality of ordered structures. A filter material may include a layer of porous material and a plurality of re-entrant structures disposed on a surface of the layer, each of the re-entrant structures including a stem and a cap, where the caps of adjacent structures are attached to each other to form a plurality of pores, where each pore is disposed between adjacent re-entrant structures.

Abstract: An ink jet droplet generator is described, including a nozzle plate bonded to a carrier. A tuned piezo crystal and metal structure projects into an ink cavity and is mounted on a print head structure. The nozzle carrier is separated by a spacer from the print head structure and seals are provided to seal the cavity. A pillar is provided with a height slightly greater than that of the spacer between the print head structure and the nozzle carrier. The spacer is isolated from the print head structure, pillar and nozzle carrier by seals and O-ring which surrounds the pillar. In another embodiment, layers of acoustically absorbent material are provided between the spacer and each of the print head structure and nozzle element.

Abstract: A modulating device for breaking ink jets in an ink jet printing machine into trains of uniform droplets comprises a nozzle plate 24 provided with a substantially linear array of nozzles and forming one wall of an ink cavity 23; and acoustic generator in the form of an elongate body 26 projecting towards the nozzle plate to transmit acoustic vibrations into ink into the cavity. The body is shaped and tuned to vibrate substantially only in the longitudinal mode and at a resonant frequency which is within ten percent of a frequency to excite natural resonant vibrations in the ink in the cavity between the end of the body and the nozzle plate, the width of the body being less than the length of the nozzle array or of that part of the array associated with that body.

Abstract: A continuous ink jet printer has main deflection electrodes 7 and 8 and a subsidiary deflection electrode 14 having a recess front face 16 which defines a cavity 17. Unwanted satellite droplets entrained by the main droplets 4 are deflected into, and form vortices in, the cavity 17, before coalescing on the surface of the electrode 14 for collection.