Liquid jet modulator with piezoelectric hemispheral transducer

A drop-on-command modulator for generating liquid drops singularly, which comprises:

• a. first and second hemispherical piezoelectric transducers having formed therein first and second central bores, respectively;
• b. a first backing having a hemispherical well on one face thereof for accommodating said first of said transducers, and further having a throughbore aligned with said first of said central bores;
• c. a second backing bonded to said first backing about said hemispherical well, and bonded to the outer convex surface of said second of said transducers about said second of said central bores to form a first liquid chamber between said second backing and said first of said transducers;
• and
• d. a nozzle plate bonded to said second backing to form a second liquid chamber between said nozzle plate and said second of said transducers, said nozzle plate having an orifice aligned with said throughbore and said first and said second central bores.

A drop-on-command modulator for generating liquid drops singularly, which comprises:

• a. a first backing having a first throughbore and a hemispherical well formed into one face thereof;
• b. a hemispherical piezoelectric transducer seated within said well and having a central bore in alignment with said first throughbore;
• c. a nozzle plate bonded to said first backing to form a liquid chamber between said plate and said transducer, said plate having an orifice in liquid communication with said first throughbore, said central bore and said chamber;
• and
• d. a second backing bonded to said first backing and located upstream from said first throughbore, said second backing having a second throughbore in alignment with said first throughbore and further having fluid feedback bores depending from said second throughbore to oppose the reverse flow of liquid from said chamber.

A liquid jet modulator for the production of droplets over a wide band of drop rates comprising:

• a. a hemispherical piezoelectric transducer;
• b. a feed tube passing through said transducer;
• c. a backing material encapsulating said transducer and feed tube;
• and
• d. a nozzle at one end of said feed tube partially encapsulated in said backing material.