Method of manufacturing multi-layered flextensional piezoelectric transducer

• US 6,156,145 A
• Filed: 08/21/1998
• Issued: 12/05/2000
• Est. Priority Date: 08/21/1998
• Status: Expired due to Term

• Current Assignee: Face International Corp.
• Original Assignee: Face International Corp.
• Inventors: Clark, Stephen
• Primary Examiner(s): YAO, SAMCHUAN CUA
• Application Number:
  US09/138,462
• Time in Patent Office: 837 Days
• Field of Search: 29/25.35, 29/446, 156/160, 156/242, 156/245, 156/311, 156/322, 156/309.9, 156/228
• US Class Current: 156/160
• CPC Class Codes: B32B 2315/02 Ceramics
• CPC Class Codes: B32B 37/12 characterised by using adhesives
• CPC Class Codes: B32B 38/0036 Heat treatment for heating or cooling of layers during lamination B32B37/06, B32B37/08
• CPC Class Codes: B32B 38/1866 conforming the layers or laminate to a convex or concave profile
• CPC Class Codes: H10N 30/073 by fusion of metals or by adhesives
• CPC Class Codes: H10N 30/2041 Beam type
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49863 with prestressing of part

Abstract

A method for manufacturing a multi-layer piezoelectric transducer having enhanced mechanical output displacement capability resulting from an increase in the amount of "pre-stress" applied to the electroactive (ceramic) layer by the pre-stress layer. The pre-stress layer is heated to a temperature above the temperature of the ceramic layer and bonded at an elevated temperature to the ceramic layer, such that, as the pre-stress layer subsequently cools down to ambient temperature, it applies a compressive stress to the ceramic layer. During the step of cooling the layers to ambient temperature, the temperature drop of the pre-stress layer is greater than the temperature drop of the ceramic layer, thereby increasing the amount of "pre-stress" applied to the electroactive (ceramic) layer by the pre-stress layer.

Claims

1. A method of manufacturing a piezoelectric transducer comprising the steps of:

selecting a thermoplastic adhesive material having a melting temperature and having a first coefficient of thermal contraction;

wherein said step of selecting a thermoplastic adhesive material comprising selecting an imide

selecting a first solid member having an exposed first surface and having a second coefficient of thermal contraction, said first solid member comprising a piezoelectric material;

wherein said step of selecting a first solid member comprises selecting an electroactive ceramic element;

selecting a second solid member having an exposed second surface and having third coefficient of thermal contraction;

wherein said step of selecting said second solid member comprises selecting a metallic member;

heating said thermoplastic adhesive material and said second solid member to a first temperature above said melting temperature;

bringing said thermoplastic adhesive material into contact with said first surface of said first solid member and said second surface of said second solid member so as to form a composite structure while said thermoplastic adhesive material and said second solid member are at said first temperature;

applying pressure to said composite structure in a direction perpendicular to each of said first and second surfaces;

wherein said step of applying pressure to said composite structure comprises placing said composite structure between a first press member and a deformable liner of a second press member, and drawing said first press member toward said second press member;

and wherein said deformable liner of said second press member comprises a deformable bladder filled with a fluid;

after said step of applying pressure to said composite structure, cooling said composite structure to a third temperature below said melting temperature;

whereby said step of cooling said composite structure to said third temperature induces a compressive stress into said first solid member;

wherein said step of cooling said composite structure to a third temperature below said melting temperature inducing said compressive stress into said first solid member deforms said composite structure into an arcuate shape;

after said step of cooling said composite structure to a third temperature, releasing said pressure applied to said composite structure; and

then

cooling said composite structure to ambient temperature, wherein said step of cooling said composite structure to ambient temperature induces a compressive stress into said first solid member.