Abstract: A multi-channel array droplet deposition apparatus has a base sheet comprising a layer of piezo-electric material poled normal thereto, an array of parallel, open-topped droplet liquid channels provided by upstanding channel separating walls formed in the layer, electrodes on channel facing surfaces of the walls, a channel closure sheet bonded to the walls, nozzles respectively communicating with the channels and a droplet liquid supply connecting with the channels, the closure sheet having an array of parallel conductive tracks thereon paced at intervals corresponding with the channel spacing and located parallel to and opposite the channels and bonds, which preferably are solder bonds, mechanically and electrically connect each track to the electrodes of the channel facing walls of the channels opposite thereto and seal the closure sheet to the channels.

Abstract: A method of manufacturing an ink jet print head includes the steps of bonding a body of piezoelectric material to a base plate and cutting channels into the piezoelectric material to form ink chambers which are actuated by applying voltages to electrodes provided on surfaces of the chambers. The base plate carries IC's which contain the drive circuitry for actuating the ink chambers. To ensure reliable electrical connection between the chamber electrodes and the IC's, the electrodes and conducting tracks on the base plate are formed in a single step by depositing a conductive layer over both the PZT body and the base plate. A step of masking or selective removal of material may be performed to achieve the necessary patterning of the electrodes and tracks.

Abstract: A nozzle in a nozzle plate for an inkjet printhead is formed by directing a laser beam at a nozzle plate. Accurate control of the divergence of the beam is achieved by splitting the beam into sub-beams, each sub-beam having divergence with an origin lying apart from the point at which the beam is created by splitting, and thereafter recombining the sub-beams. Greater accuracy in the taper and inlet shape of the manufactured nozzle is thereby obtained.

Abstract: Data input to an ink jet printer is subjected to a transformation which is the inverse of a transformation representing the errors in ink drop placement which have been measured for that specific ink jet printer.

Abstract: Droplet deposition apparatus comprises a fluid chamber comprising an actuator actuable by electrical signals to effect ejection of droplets from the fluid chamber, a drive circuit for supplying the electrical signals; and a conduit for supplying droplet fluid to said fluid chamber, the drive circuit being in substantial thermal contact with the conduit so as to transfer a substantial part of the heat generated in the drive circuit to the droplet fluid.

Abstract: Droplet deposition apparatus includes a base and a printhead adjustably mounted on the base and positionable relative to a datum on the base such that a swath or print produced by the printhead is in a predetermined position relative to the datum, the base being locatable on a printer using the datum. This can enable the printer to be easily replaced without any loss of alignment of the produced print swath relative to the carriage or body of the printer.

Abstract: A component for a drop-on-demand piezoelectric printhead is formed from a block of piezoelectric material and a substrate. The block of piezoelectric material has grooves formed in its lower surface and is attached to the substrate using an adhesive that is applied in sufficient quantity such that adhesive enters the grooves cut into the piezoelectric material. Upper grooves are sawn into the piezoelectric material through to the glue-filled lower channels in order to form ejection channels, the walls of which are separated from one another by means of a glue fillet.

Abstract: A droplet deposition apparatus includes an elongate chamber having a nozzle through which in operation droplets of liquid are ejected from the chamber for deposition, means for varying the pressure of liquid in the chamber by varying the volume thereof to effect ejection of the droplets and means for causing a flow of liquid in the chamber in addition to that necessary to replenish the ejected droplets, the flow passing across the nozzle to clean it.

Abstract: A vacuum drum assembly for a printing machine has a drum with an array of passageways distributed along its length and around its periphery. The passageways permit air to flow from outside the drum to inside the drum in response to reduced air pressure inside the drum. The assembly also has an array of valve members, each valve member being movable between a closed position in which that valve member restricts at least one of the passageways and an open position in which the restriction of that passageway or those passageways is reduced. The assembly is arranged such that, when a partial area of the drum is wrapped with a sheet of material, at least some of the valves for the passageways adjacent the edges of that area are open, and the valves for the passageways which are not covered by the sheet and are not adjacent the edges of that area are closed.

Abstract: In ink jet printing, a UV curable undercoat is first deposited on a substrate. The ink and undercoat are cured together. The thickness of the undercoat varies inversely with the thickness of the ink, so that a flat print surface is achieved. Application of an undercoat may be disabled on text material, to preserve edge definition.

Abstract: A filter assembly for ink for a printer includes at least one pair of supported filter elements which are in stacked arrangement and includes a filter housing. The filter assembly is adapted for conveying the ink through the filter elements so that the ink flow through both filter elements is either into or out of the volume between the filter elements.

Abstract: In droplet deposition apparatus comprising one or more independently actuable ink ejection chambers, electrical signals are applied to reduce variation in the temperature of the droplet fluid between chambers and with variations in droplet ejection input data. Short potential difference pulses, suitable for influencing the temperature of the droplet fluid in a chamber, can be generated by application of longer duration voltages to ink chamber actuation means.

Abstract: An accepter-doped “hard” PZT is used in a piezoelectric print head instead of the conventional “soft” donor-doped material. The print head preferably is of a chevron side-shooter configuration and is advantageous for high-definition grey-scale printing.

Abstract: A drop-on-demand piezo-electric printhead has channel walls defined by piezo-electric material (10) with electrodes (26) along the length thereof. In portions of the channels which are open to an ink supply conduit, the piezo material is locally disabled, e.g. by reducing the width of the electrode or by interposing a material (40) of lower dielectric constant between the electrode and the piezo material. A lower capacitive load results.

Abstract: A method for prevention of nozzle plate peel for inkjet printheads. The nozzle plate is bonded to the nozzle, with a layer of adhesive, and to a support, with a thicker layer of adhesive. This extra support prevents the peeling of the nozzle plate under the forces generated by, for example, a wiper blade passing over it. Spacers between the nozzle plate and support ensure the correct uniformity and constant thickness of the adhesive layer.

Abstract: A radiation curable ink jet ink having a viscosity not greater than 35 mPa.s at 30° C. and comprising a colorant component, a diluent consisting essentially of reactive liquid material and, optionally, at least one photopolymerization catalyst and wherein the reactive liquid material is formed of both monofunctional and polyfunctional material and comprises 5 to 30% by weight of at least one oligomer.

Abstract: Droplet deposition apparatus comprising first and second channels (82a, 82b), one end of each channel communicating with a single, common supply chamber (40) for supply of droplet liquid and the respective other ends of the first and second channels each communicating with a respective further supply chamber (88, 92) for supply of droplet liquid; each of said first and second channels having an opening (96a, 96b) for ejection of droplets therefrom; and actuator means being associated with each channel for effecting the ejection of droplets.

Abstract: A piezoelectric printhead or other droplet deposition apparatus has parallel liquid containing channels defined by a base and displaceable walls, and covered by a cover number. The channels each have at least one nozzle for ejecting droplets. Each nozzle may be disposed in the base, the cover then having two ink supply parts spaced lengthwise of each channel on opposite sides of the nozzle. Alternatively two longitudinally spaced nozzles may be provided in the base of each channel. The cover may have a conductive track corrected to wall-displacing electrodes, the points of connection being outside the channels.

Abstract: In droplet deposition apparatus comprising one or more independently actuable ink ejection chambers, electrical signals are applied to reduce variation in the temperature of the droplet fluid between chambers and with variations in droplet ejection input data. Short potential difference pulses, suitable for influencing the temperature of the droplet fluid in a chamber, can be generated by application of longer duration voltages to ink chamber actuation means.

Abstract: A method of polarizing a portion of a monolithic piezoelectric actuator element for use in droplet deposition apparatus where the element has first and second portions, includes the steps of placing the first portion of the element at an equipotential and generating a polarizing electric field across the second portion between said first portion and a further conducting layer.