Patent ID: 7828420

Claim:
A method for operating a liquid drop generator for selective formation of large-volume droplets and small-volume droplets, said method comprising the steps of: providing a droplet generator having a nozzle opening and an adjustable stimulation device; supplying a liquid under pressure to the droplet generator such that a liquid stream of a predetermined diameter D emanates from the nozzle opening; activating the stimulation device to produce a first set of perturbations on the diameter of the liquid stream, said perturbations having a period x such as to cause the liquid stream to form into small-volume droplets; selectively activating the stimulation device to produce a second set of perturbations on the diameter of the liquid stream, said second set of perturbations having a period Nx such as to cause a segment of the liquid stream to form into a large-volume droplet, whereby the large-volume droplet is N times the volume of the small-volume droplets; and further activating the stimulation device to produce a third set of perturbations on the diameter of the liquid stream during the period Nx, the time period between the perturbations of the third set of perturbations being sufficiently short that the segment of the liquid stream that forms the large-volume droplet is not broken up thereby.