Bonded piezoelectric bending transducer and process for producing the same

• US 5,404,067 A
• Filed: 05/26/1994
• Issued: 04/04/1995
• Est. Priority Date: 08/10/1990
• Status: Expired due to Term

• Current Assignee: Argillon GmbH (Johnson Matthey PLC)
• Original Assignee: Siemens AG
• Inventors: Stein, Christian, Mockl, Thomas
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/249,693
• Time in Patent Office: 313 Days
• Field of Search: 310/330-332, 310/363-365
• US Class Current: 310/330
• CPC Class Codes: H10N 30/2042 Cantilevers, i.e. having one fixed end

Abstract

A piezoelectric bending transducer includes two piezoceramic layers each having two sides and electrodes on both of the sides. A graphite fiber layer is glued between the piezoceramic layers with an epoxy resin. The graphite fiber layer has a greater length than the two piezoceramic layers defining an exposed part of the graphite fiber layer. A copper foil is glued to the exposed part. The copper foil has an area for disposition of a solder contact. A process for producing a bending transducer includes placing a graphite fiber layer impregnated with incompletely hardened epoxy resin between two polarized piezoceramic layers. The graphite fiber layer is glued between the piezoceramic layers upon hardening of the epoxy resin. A copper foil is glued onto the graphite fiber layer, preferably simultaneously with the gluing of the two piezoceramic layers.

Claims

1. A piezoelectric bending transducer, comprising:

two piezoceramic layers each having two sides and electrodes on both of said sides;

a conductive elastic intermediate layer in the form of a graphite fiber layer glued between said piezoceramic layers with an epoxy resin for forming an electrically conductive contact between said electrodes and said graphite fiber layer;

said graphite fiber layer having a greater length than said two piezoceramic layers defining a projection part of said graphite fiber layer projecting outwardly from between said piezoceramic layers; and

a copper foil glued to said projecting part, said copper foil having an area for disposition of a solder contact for defining said graphite fiber layer as a common electrode.

2. The bending transducer according to claim 1, wherein said copper foil has a pretreated surface facing toward said graphite fiber layer.

3. The bending transducer according to claim 2, wherein said surface of said copper foil is covered with a rough layer of a material selected from the group consisting of zinc, nickel and copper.

4. The bending transducer according to claim 1, wherein said graphite fiber layer is a fabric having carbon fibers between which said epoxy resin is disposed.