Abstract A tuned plate acoustic projector having a tuned plate that has its periphery bonded to and supported by a housing. The outer face of the tuned plate is exposed to a fluid medium in which it is desired to generate acoustic waves. One end of a piezoelectric transducer is in contact with the central region of the inner face of the tuned plate and the other end is in contact with a mass slug that has a relatively large inertia base for the transducer. A compressive bias force is applied to the transducer to maintain the transducer in compression and to thereby prevent the generation of excessive tensile stresses in the transducer during operation. The thickness of the tuned plate is selected or tuned so that the propagation velocity of the flexural waves in the tuned plate matches the acoustic propagation velocity of the external fluid medium. An approximately hemispherical acoustic beam is obtained in the fluid medium which is the composite of a search light beam which is generated by the piston action of the transducer against the central region of the tuned plate and a toroidal rim fire beam which is generated by the transfer of energy from the radiating flexural waves in the tuned plate into acoustic waves in the fluid medium.
An acoustic projector comprising: a. a plate having a lower surface an an upper surface; b. said plate having the periphery supported by a structure and an unsupported central section; c. said upper surface being exposed to an acoustic transmitting medium; d. motion generating means for imparting an upward motion to the lower surface of the unsupported central section of said plate; e. said plate having a predetermined thickness; whereby f. said thickness is selected such that the ourwardly radiating velocity of the flexural waves imparted by said means is about equal to the velocity of sound of said medium.
Claim 2
Dependent Claim
100 words
An acoustic projector comprising: a. a plate having a lower surface an an upper surface; b. said plate having the periphery supported by a structure and an unsupported central section; c. said upper surface being exposed to an acoustic transmitting medium; d. motion generating means for imparting an upward motion to the lower surface of the unsupported central section of said plate; e. said plate having a predetermined thickness; whereby f. said thickness is selected such that the ourwardly radiating velocity of the flexural waves imparted by said means is about equal to the velocity of sound of said medium.
Claim 3
Dependent Claim
15 words
The projector of claim 1 wherein: a. said motion generating means is a piezoelectric transducer.
Claim 4
Dependent Claim
26 words
The projector of claim 2 including: a. support means for maintaining said piezoelectric transducer in about constant compressive loading against said inner surface of said plate.
Claim 5
Dependent Claim
14 words
The projector of claim 3 wherein: a. said support means includes an elastomeric member.
Claim 6
Dependent Claim
65 words
The projector of claim 4 wherein: a. said support means includes a mass slug having an upper surface and a lower surface; b. said piezoelectric transducer being positioned between and in contact with said lower surface of said plate and said upper surface of said mass slug; whereby c. said mass slug is supported by and forced against said piezoelectric transducer by said elastomeric material.
Claim 7
Dependent Claim
33 words
The projector of claim 5 wherein: a. said support means includes a support plate; and b. said support plate is positioned between said lower surface of said mass slug and said elastomeric member.
Claim 8
Dependent Claim
87 words
The projector of claim 6 wherein: a. the initial upward motion of said piezoelectric transducer against said plate generates a directional acoustic beam in a direction about vertical to said upper surface of said plate; and b. said radiating flexural waves generate a toroidal acoustic beam radiating outwardly about horizontal to said upper surface of said plate; whereby c. the resultant acoustic beam generated by said directional acoustic beam and said toroidal acoustic beam is a hemispherical beam propagating outward from said upper surface of said plate.
Claim 9
Dependent Claim
53 words
The projector of claim 7 wherein: a. said piezoelectric transducer is pulsed with at least one pulse at a predetermined frequency which result in a plurality of flexural waves simultaneously radiating outward from the center of said plate at a velocity that is about equal to the velocity of sound in said medium.