Patent ID: 8191982

Claim:
A method of projecting liquid as jets or droplets from a nozzle provided on a transducer formed by a region of a material layer, the method comprising the steps of: supplying liquid to an inner end of the nozzle; exciting the nozzle to cause movement of the nozzle in a direction substantially aligned with the nozzle axis in order to project liquid as a droplet from an outer face of the nozzle; wherein the step of exciting the nozzle comprises sequentially driving the transducer with a first rising voltage change, a first falling voltage change, a second rising voltage change and a second falling voltage change; wherein the first rising voltage change and the first falling voltage change are timed so that they enhance the movement of the material layer, and the second rising voltage change and the second falling voltage change are timed so that they substantially cancel the movement of the material layer; wherein the movement of the material layer following any edge is mono-modal; and wherein the duration between the first rising voltage change and the first falling voltage change is up to half a period of the movement of the material layer.