Patent ID: 8171798

Claim:
A liquid dispensing apparatus comprising: a container having a chamber adapted for holding a liquid; an orifice positioned at an end of the chamber for allowing a free surface of the liquid to form when the liquid is held in the chamber, the free surface being the region where the liquid interfaces with the environment outside of the container, the orifice being configured to retain the liquid in the container if the container is positioned with the orifice facing in a downward direction and the liquid is being held in the chamber; an acoustic transducer means at least partially positioned in the chamber for periodically propagating a focused acoustic beam toward the orifice and through at least some of the liquid when the liquid is being held in the chamber, the focused acoustic beam being capable of causing a droplet of the liquid to be ejected from the free surface of the liquid when the focused acoustic beam is focused at or near the free surface; and a calibration surface positioned in the chamber for intercepting a part of the focused acoustic beam to generate a reflected acoustic wave.