Flextensional low frequency sound projector

Patent metadata

Field	Value
Publication number	US-12382213-B2
Application number	US-202318212917-A
Country	US
Kind code	B2
Filing date	Jun 22, 2023
Priority date	Aug 12, 2022
Publication date	Aug 5, 2025
Grant date	Aug 5, 2025

Abstract

Proposed is a flextensional low-frequency sound projector including a piezoelectric actuator including a piezoelectric stack formed by stacking piezoelectric element and generating vibration in a lengthwise direction in response to an electrical signal that is input, and a stave mounted on the piezoelectric actuator in such a manner as to encompass an outer surface of the piezoelectric actuator and generating the vibration in the lengthwise direction, which is generated by the piezoelectric actuator, as vibration in a lateral direction perpendicular to the outer surface of the piezoelectric actuator, wherein the stave activates two vibration modes that use different resonance frequencies. The flextensional low-frequency sound projector that utilizes two vibration modes results from improving an existing flextensional low-frequency sound projector that is driven in a single vibration mode and thus has a narrow frequency bandwidth.

First claim

What is claimed is:

1. A flextensional low-frequency sound projector comprising:
a piezoelectric actuator including a piezoelectric stack formed by stacking piezoelectric element and generating vibration in a lengthwise direction in response to an electrical signal that is input, and a pair of weighted objects that are brought into surface contact with both ends, respectively, of the piezoelectric stack; and
a stave mounted on the piezoelectric actuator in such a manner as to encompass an outer surface of the piezoelectric actuator and generating the vibration in the lengthwise direction, which is generated by the piezoelectric actuator, as vibration in a lateral direction perpendicular to the outer surface of the piezoelectric actuator,
wherein the stave activates two vibration modes that use different resonant frequencies.

2. The flextensional low-frequency sound projector of claim 1 , wherein the stave comprises:
a flextensional bar mounted on the pair of weighted objects by being brought into contact with outer surfaces of the weighted objects; and
bending bars being continuous with both ends, respectively, of the flextensional bar.

3. The flextensional low-frequency sound projector of claim 2 , wherein a plurality of the flextensional bars are arranged to be spaced away along a circumference of the piezoelectric stack, and
wherein a plurality of the bending bars are arranged to be spaced apart along the circumference of the piezoelectric actuator.

4. The flextensional low-frequency sound projector of claim 3 , wherein the flextensional bar is shaped in a manner that is bent in a width direction thereof.

5. The flextensional low-frequency sound projector of claim 4 , wherein an upper surface of the flextensional bar is shaped in a manner that is bent in a lengthwise direction thereof.

6. The flextensional low-frequency sound projector of claim 5 , wherein the upper surface of the flextensional bar is concavely shaped.

7. The flextensional low-frequency sound projector of claim 5 , wherein the upper surface of the flextensional bar is convexly shaped.

8. The flextensional low-frequency sound projector of claim 3 , further comprising:
an insulating plate brought into surface contact with the weighted object and interposed between the piezoelectric stack and the weighted object.

9. The flextensional low-frequency sound projector of claim 1 , wherein both ends of the flextensional bar are brought into contact with the weighted objects, respectively, that constitute one pair, and a lower surface of one end portion of the bending bar is brought into surface contact with a lateral surface of the weighted object.

10. The flextensional low-frequency sound projector of claim 9 , further comprising:
a baffle configured in such a manner that one surface thereof is brought into contact with the weighted object and that a lateral surface thereof is brought into contact with an inner surface of the bending bar; and
a sound window having an inner surface whose shape corresponds to the shape of an outer surface of the stave and surrounding the stave.

Assignees

• Agency Defense Dev

Inventors

• Je Yub
• Lim Soo-Hyun
• Cho Yo-Han
• Lee Jeong-Min
• Seo Hee-Seon

Classifications

• H04R17/10

  Resonant transducers, i.e. adapted to produce maximum output at a predetermined frequency · CPC title

• H04R17/00 Primary

  Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) · CPC title

• G01S7/521

  Constructional features · CPC title

• H04R1/2811 Primary

  for loudspeaker transducers · CPC title

• B06B1/0644 Primary

  using a single piezoelectric element (B06B1/0688 takes precedence) · CPC title