Xaar Technology Limited

Michael Reddish

Nicholas Marc Jackson

Andrew Cox

Angus Condie

Wolfgang Voit

A droplet deposition apparatus comprising a droplet deposition head, a fluid supply and a controller, wherein: the droplet deposition head comprises one or more fluid chambers each having a nozzle, a fluid inlet path having a fluid inlet into the head, and ending in the one or more nozzles, and a fluid return path starting at the one or more nozzles and ending in a fluid return of the head; each fluid chamber comprises two opposing chamber walls comprising piezoelectric material and deformable upon application of an electric drive signal so as to eject a fluid droplet from the nozzle; the fluid supply is configured to supply a fluid to the fluid inlet at a differential pressure as measured between the fluid inlet and the fluid return; and the controller is configured to apply a drive signal to the piezoelectric chamber walls such that the nozzle or nozzles deposit droplets of a fluid having a viscosity in the range from 45 mPa·s to 130 mPa·s at a jetting temperature between 20° C. and 90° C., and wherein the differential pressure applied by the fluid supply causes a fluid return flow into the fluid return at a rate of between 50 ml/min and 200 ml/min. A method of operating the droplet deposition apparatus, and a control system for carrying out the method, are also provided.

Piezoelectric droplet deposition apparatus optimised for high viscosity fluids, and methods and control system therefor

A droplet ejection apparatus including a droplet deposition head, actuating circuitry and head controller circuitry. The droplet deposition head having an array of actuating elements and a corresponding array of nozzles. The actuating circuitry applies drive waveforms to the actuating elements causing the ejection of fluid in the form of droplets through the array of nozzles and onto deposition media, which are moved relative to the droplet deposition head. The head controller circuitry is configured to receive an input set of ejection data, generate a series of sub-sets of ejection data based on the input set, and send the series of sub-sets of ejection data to the actuating circuitry. The actuating circuitry is further configured so as to, for each sub-set of ejection data, apply drive waveforms to the actuating elements such that they repeatedly eject droplets from one or more nozzles, thus depositing successive rows of droplets. The one or more nozzles and the sizes of the droplets ejected therefrom are determined by the current sub-set of ejection data. Each of the one or more nozzles ejecting droplets with a substantially constant frequency of 1/T. The apparatus is further configured to receive deposition media speed data, which indicates the current speed of relative movement of the head with respect to the deposition media. The apparatus is further configured such that the head switches from ejecting droplets in accordance with a current sub-set of ejection data to ejecting droplets in accordance with a consecutive sub-set of ejection data in the series at a time determined in accordance with the media speed data, with the time interval between starting ejecting droplets in accordance with successive sub-sets of ejection data varying inversely with the current speed of relative movement of the droplet deposition head.

Method, apparatus and circuitry for droplet ejection

A droplet ejection apparatus comprising: a droplet deposition head comprising an array of actuating elements and a corresponding array of nozzles; actuating circuitry, configured to apply drive waveforms to said actuating elements, thereby causing the ejection of fluid in the form of droplets through said array of nozzles onto deposition media, which are moved relative to the head; and head controller circuitry, configured to: receive an input set of ejection data; generate a series of sub-sets of ejection data based on the input set; and send said series of sub-sets of ejection data to said actuating circuitry; wherein the actuating circuitry is further configured so as to, for each sub-set of ejection data, apply drive waveforms to said actuating elements such that they repeatedly eject droplets from one or more nozzles, thus depositing successive rows of droplets, the one or more nozzles and the sizes of the droplets ejected therefrom being determined by the current sub-set of ejection data, each of the one or more nozzles ejecting droplets with a substantially constant frequency of 1/T; wherein the apparatus is configured to receive deposition media speed data, which indicates the current speed of relative movement of the head with respect to the deposition media; and wherein the apparatus is configured such that the head switches from ejecting droplets in accordance with a current sub-set of ejection data to ejecting droplets in accordance with a consecutive sub-set of ejection data in the series at a time determined in accordance with said media speed data, with the time interval between starting ejecting droplets in accordance with successive sub-sets of ejection data varying inversely with the current speed of relative movement of the head.

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Cambridge, United Kingdom

Michael Reddish