Randy L. Fagerquist - Beavercreek OH,
Ornit Hadar - Vancouver,
Julia A. Gayhart - Tipp City OH,
Robert J. Simon - Bellbrook OH,
A drop generator is operated to form large-volume and small-volume droplets by providing a droplet generator having a nozzle and an adjustable stimulation device; supplying liquid to the droplet generator such that a stream of diameter D emanates from the nozzle; activating the stimulation device to produce a first set of perturbations on the liquid stream, the perturbations having a period x such as to cause the liquid stream to form into small-volume droplets; selectively adjusting the stimulation device to produce a second set of perturbations on the liquid stream, the 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 adjusting the stimulation device to produce a third set of perturbations on the liquid stream during the period Nx.