Fluid drop projecting head using taper-shaped chamber for generating a converging surface wave

Abstract

A fluid drop projecting apparatus which can fly, one by one, fluid drops far smaller than the opening bore from which the drops are projected, and moreover cay readily vary the size of the fluid drops, is provided. To this end, surface waves travelling toward a fluid drop projecting point are applied on the free surface of fluid in a fluid drop projecting chamber having an opening. The surface waves are generated by a surface wave generator including the fluid drop projecting chamber, a diaphragm and a piezo actuator. As the surface waves are generated by the surface wave generator at substantially equal distances from a fluid drop projecting point, the height of the surface waves gradually increases, amplified by their interference, and fluid drops are separated at and projected from the fluid drop projecting point.