Martha Elaine Wilson

US Patent:

55530354, Sep 3, 1996

Filed:

Oct 21, 1994

Appl. No.:

8/327167

Inventors:

Hewlett E. Melton - Sunnyvale CA
Martha G. Wilson - Andover MA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

H04R 1700

US Classification:

367140

Abstract:

A method of forming a transducer device having integral transducer and impedance matching portions includes forming grooves partially through a thickness of a piezoelectric member. A groove volume fraction at the impedance matching portion controls the electrical impedance. The impedance matching portion may be at either or both of the front and rear surfaces of the transducer portion, which generates acoustic wave energy in response to application of a drive signal. The drive signal is introduced by electrodes. In one embodiment, the electrode at the impedance matching portion extends into the grooves, but preferably a filler material is selected and deposited to allow use of a planar electrode. An alternative embodiment to fabricating the transducer device is to assemble piezoelectric material. For example, an integral transducer and impedance matching portions may be formed by using molding techniques or by stacking dimensionally different thin piezoelectric layers.