Flexion-plate hydrophones

Claim 2

A bidirectional flexion-plate hydrophone comprising: only a single flexible cicular membrane of substantially constant thickness, two rigid rings enclosing the periphery of said membrane, a piezoelectric disc on at least one face of said membrane, the exterior diameter of which is smaller than the interior diameter of said rigid rings wherein said membrane, said rings and said discs being completely embedded in an elastomeric material forming a unit attached to a rigid support only through said elastomeric material.

Claim 3

A hydrophone as claimed in claim 1, wherein: the elastomeric material covering the side of the membrane facing the disc has a uniform thickness which is less than that on other portions of the hydrophone.

Claim 4

A hydrophone as claimed in claim 2, wherein: the thickness of the elastomeric material covering the side of the membrane facing the disc is between 0.5 mm and 2 mm.

Claim 5

A hydrophone as claimed in claim 3, wherein: said rings have an interior diameter of approximately 24 mm, and said thickness is approximately 1 mm.

Claim 6

A hydrophone as claimed in claim 4, wherein: the elastomeric material is polyurethane.

Claim 7

A hydrophone as claimed in claim 1, wherein: the disc is lead titanium zirconate ceramic.

Claim 8

A bidirectional flexion-plate hydrophone for attachment to a rigid support and for receiving acoustic waves with good sensitivity and directivity over the band of sonic frequencies, comprising: only a single flexible circular membrane of substantially constant thickness, two rigid rings enclosing the periphery of said membrane, a piezoelectric disc on at least one face of said membrane, the outer diameter of which is smaller than the inner diameter of said rigid rings, wherein said membrane, said rings and said discs are embedded in an elastomeric material coating which comprises on each face a central acoustically transmissive window, with a smaller uniform thickness, and a circular thicker rim surrounding said window.

Claim 9

A bidirectional flexion-plate hydrophone for attachment to a rigid support and for receiving acoustic waves with good sensitivity and directivity over the band of sonic frequencies, comprising: only a single flexible circular membrane of substantially constant thickness, two rigid rings enclosing the periphery of said membrane, a piezoelectric disc on at least one face of said membrane, the outer diameter of which is smaller than the inner diameter of said rigid rings, wherein said membrane, said rings and said discs are embedded in an elastomeric material coating which comprises on each face a central acoustically transmissive window, with a smaller uniform thickness, and a circular thicker rim surrounding said window.

Claim 10

A hydrophone as claimed in claim 7 wherein: the elastomeric material each acoustically transmissive window has a uniform thickness of between 0.5 mm and 2 mm which is less than that on other portions of the hydrophone.

Claim 11

A bidirectional flexion plate hydrophone for attachment to a rigid support and for receiving acoustic waves with good sensitivity and directivity over the band of sonic frequencies, comprising: only one single flexible circular metallic membrane of substantially uniform thickness, two rigid rings directly contacting the periphery of said membrane without any elastomeric material between said rings and said membrane, a piezoelectric disc on each face of said membrane, the exterior diameter of which is smaller than the interior diameter of said rigid rings, wherein said membrane, said rings and said discs are completely embedded in an elastomeric material coating which comprises contiguous to each disc a central circular acoustically transmissive window of reduced uniform thickness, facing said piezoelectric discs, and a thicker rim, surrounding said window and enclosing said rings, wherein rigid means for securing said hydrophone to a rigid support is embedded in said coating, said elastic material coating forming the only connection between said rigid means and said rings.

Claim 12

A bidirectional flexion plate hydrophone for attachment to a rigid support and for receiving acoustic waves with good sensitivity and directivity over the band of sonic frequencies, comprising: only one single flexible circular metallic membrane of substantially uniform thickness, two rigid rings directly contacting the periphery of said membrane without any elastomeric material between said rings and said membrane, a piezoelectric disc on each face of said membrane, the exterior diameter of which is smaller than the interior diameter of said rigid rings, wherein said membrane, said rings and said discs are completely embedded in an elastomeric material coating which comprises contiguous to each disc a central circular acoustically transmissive window of reduced uniform thickness, facing said piezoelectric discs, and a thicker rim, surrounding said window and enclosing said rings, wherein rigid means for securing said hydrophone to a rigid support is embedded in said coating, said elastic material coating forming the only connection between said rigid means and said rings.

Claim 13

A hydrophone as claimed in claim 9 wherein each window is exposed for operative communication of sound from the exterior of the hydrophone.