Parametric loudspeaker with improved phase characteristics

• US 20050089176A1
• Filed: 11/08/2004
• Published: 04/28/2005
• Est. Priority Date: 10/29/1999
• Status: Abandoned Application

• Current Assignee: American Technology Incorporated (Emerson Electric Company)
• Original Assignee: American Technology Incorporated (Emerson Electric Company)
• Inventors: Norris, Joseph O., Croft, James J. III, Norris, Elwood G.
• Application Number:
  US10/984,343
• Publication Number:
  US 20050089176A1
• Time in Patent Office: Days
• US Class Current: 381/79
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00
• CPC Class Codes: H04R 2217/03 Parametric transducers where sound is generated or captured by the acoustic demodulation of amplitude modulated ultrasonic waves

Abstract

A parametric loudspeaker which uses multiple piezoelectric bimorph transducers. These multiple piezoelectric bimorphs have a resonant frequency which varies from unit to unit. The phase response at and near the resonant frequency changes at a very high rate with slight changes in frequency. The associated modulator electronics have a primary carrier frequency that is optimized for maximum parametric output. This is achieved by aligning the carrier frequency with the flattest portions of the phase curve for maximum phase coordination among the multiple devices.

Claims

1-22. -22. (canceled)

23. A parametric loudspeaker system comprising:

(a) a non-planar base; and

(b) at least two piezoelectric bimorph transducers mounted on the non-planar base, wherein the at least two piezoelectric bimorph transducers are individually aligned substantially equidistant to a point located both forward from and centered on the non-planar base.

24. The parametric loudspeaker system as defined in claim 23 wherein the point located both forward from and centered on the non-planar base is at a distance of greater than 0.33 meters.

25. The parametric loudspeaker system as defined in claim 23 wherein the point located both forward from and centered on the non-planar base is at a distance of less than 3.0 meters.

26. The parametric loudspeaker system as defined in claim 23 wherein the point located both forward from and centered on the non-planar base is at a distance between 0.33 to 3.0 meters.

27. A parametric loudspeaker system, comprising:

a non-planar base; and

an array of parametric sound emission areas mounted on the non-planar base, wherein the array of sound emission areas are individually aligned substantially equidistant to a point located both forward from and centered on the array of sound emission areas.

28. The parametric loudspeaker system as defined in claim 27 wherein the point located both forward from and centered on the array of sound emission areas is at a distance of greater than 0.33 meters.

29. The parametric loudspeaker system as defined in claim 27 wherein the point located both forward from and centered on the array of sound emission areas is at a distance of greater than 1.0 meters.

30. The parametric loudspeaker system as defined in claim 27 wherein the point located both forward from and centered on the array of sound emission areas is at a distance of greater than 3.0 meters.

31. The parametric loudspeaker system as defined in claim 27 wherein the point located both forward from and centered on the array of sound emission areas is at a distance between 0.33 to 3.0 meters.

32. A parametric loudspeaker system including:

(a) a point located both forward from and centered on the parametric loudspeaker system;

(b) at least two piezoelectric bimorph transducers configured in a non-planar fashion, wherein the at least two piezoelectric bimorph transducers are individually aligned substantially equidistant from the point to avoid phase distortions in the transducer output.

33. The parametric loudspeaker system as defined in claim 32 wherein the point located both forward from and centered on the non-planar base is at a distance between 0.33 to 3.0 meters.

34. The parametric loudspeaker system as defined in claim 32 further comprising a non-planar mounting means to mount the at least two piezoelectric bimorph speakers.