Electrostrictive acoustic projector and polymers used therein

• US 5,835,453 A
• Filed: 05/05/1997
• Issued: 11/10/1998
• Est. Priority Date: 07/20/1993
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Wynne, Kenneth J., Fox, Robert B., Ellinthorpe, Alan W.
• Primary Examiner(s): ELDRED, JOHN W
• Application Number:
  US08/851,544
• Time in Patent Office: 554 Days
• Field of Search: 367/157, 367/163, 367/140, 310/311, 310/334, 310/800, 29/25.35
• US Class Current: 367/140
• CPC Class Codes: B06B 1/06 operating with piezoelectric effect or with electrostriction piezoelectric or electrostrictive devices per se H10N30/00
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

Polymer materials having a low Young'"'"'s modulus, a low dielectric constant, and a high apparent piezoelectric response when subjected to a high direct bias voltage and a superimposed alternating voltage, used as the active element in an underwater acoustic signal projector of a sonar system.

Claims

1. An acoustic radiator which comprises:

at least one layer of a highly hydrophobic polymer material having a phase with a very low glass transition temperature, said polymer material having a Young'"'"'s modulus less than 4×

10⁸ Newtons per square meter, an electrostrictive response under high DC bias greater than 3 Å

ngstroms per volt, and a dielectric constant less than 10;

biasing means for applying a high dc bias voltage across said at least one layer of polymer material; and

means for superimposing a low frequency AC signal on the DC bias voltage;

wherein said polymer material is a linear poly(diorganophosphazene) having a general structure (R'"'"'R"P═

N)_n, where;

R'"'"' is selected from a group consisting of alkoxy, alkyl, aryl, or organometallic groups;

R" is selected from a group consisting of alkoxy, alkyl, aryl, or organometallic groups;

P is phosphorus;

N is nitrogen; and

n represents the degree of polymerization.

2. An acoustic radiator, as described in claim 1, wherein said radiator is an underwater acoustic radiator of a sonar system.

3. An acoustic radiator, as described in claim 1, wherein said polymer material is poly(bis(trifluoroethoxy)phosphazene), (F₃ CCH₂ O)₂ P═

N !_n.