Ultrasonic torsional mode and longitudinal-torsional mode transducer system

• US 20090236938A1
• Filed: 02/20/2009
• Published: 09/24/2009
• Est. Priority Date: 02/22/2008
• Status: Active Grant

• Current Assignee: Piezo Innovations
• Original Assignee: Piezo Innovations
• Inventors: Bromfield, George
• Granted Patent: US 8,395,299 B2
• Time in Patent Office: Days
• US Class Current: 310/323.190
• CPC Class Codes: A61B 2017/32007 with suction or vacuum means
• CPC Class Codes: A61B 2017/320089 node location
• CPC Class Codes: A61B 2017/320098 with transverse or torsional motion
• CPC Class Codes: A61C 1/07 with vibratory drive, e.g. ultrasonic
• CPC Class Codes: B06B 1/0611 in a pile

Abstract

The present invention relates to the design of piezoelectric transducer subassemblies and systems primarily intended for medical and dental applications. The invention also provides transducer subassemblies and systems with improved performance and a capability to operate more efficiently in torsional or a combined longitudinal-torsional mode of vibration. The invention enables the size and weight of torsional mode transducers to be reduced. Additionally, the electrical characteristics of these transducer systems are improved, thus enabling the transducer end effector to deliver more power to the operative site.

Claims

1. A piezoelectric transducer subassembly comprising an inhomogeneous resonator sandwiched between two separate piezoelectric stacks.

2. A piezoelectric transducer system comprising:

i) a first and a second piezoelectric stack;

wherein each stack independently comprising two or more polarized piezoelectric elements that are electrically connected in parallel;

ii) an inhomogeneous resonator sandwiched between the first and the second piezoelectric stack;

iii) a horn coupled to the first piezoelectric stack, wherein the horn has a cross section distal to the piezoelectric stack that is smaller than a cross section proximal to the piezoelectric stack; and

iv) an end effector coupled to the horn, wherein the end effector couples torsional or longitudinal-torsional vibrations to a solid or fluid medium.

3. The transducer system of claim 2, wherein the first piezoelectric stack operates with in-phase synchronism and the second piezoelectric stack operates with phase-opposite synchronism.

4. The transducer system of claim 2, wherein the first piezoelectric stack operates with in-phase synchronism and the second piezoelectric stack operates with in-phase synchronism.

5. The transducer system of claim 2, wherein the transducer system operates in a torsional mode or a longitudinal-torsional mode.

6. The transducer system of claim 2, wherein the inhomogeneous resonator is a twisted bar;

a spiral spring;

or a rod with one or more slots.

7. A piezoelectric transducer system comprising:

a first and a second piezoelectric stack;

wherein each stack has a central opening and comprises two or more polarized piezoelectric elements that are electrically connected in parallel;

i) an inhomogeneous resonator sandwiched between the first and the second piezoelectric stack;

iii) a horn, which passes through the central opening of the first piezoelectric stack and is coupled at a nodal region distal from the inhomogeneous resonator and proximal to the first piezoelectric stack, wherein the horn has a cross section distal to the piezoelectric stack that is smaller than a cross section proximal to the piezoelectric stack; and

iv) an end effector coupled to the horn, wherein the end effector couples torsional or longitudinal-torsional vibrations to a solid or fluid medium.

8. The transducer system of claim 7, wherein the first piezoelectric stack operates with in-phase synchronism and the second piezoelectric stack operates with phase-opposite synchronism.

9. The transducer system of claim 7, wherein the first piezoelectric stack operates with in-phase synchronism and the second piezoelectric stack operates with in-phase synchronism.

10. The transducer system of claim 7, wherein the transducer system operates in a torsional mode or a longitudinal-torsional mode.

11. The transducer system of claim 7, wherein the inhomogeneous resonator is a twisted bar;

a spiral spring;

or a rod with one or more slots.

12. A piezoelectric transducer system comprising a piezoelectric stack sandwiched between an inhomogeneous resonator and a horn.

13. A piezoelectric transducer system comprising:

i) one piezoelectric stack, wherein the piezoelectric stack comprises two or more piezoelectric elements;

ii) an inhomogeneous resonator coupled to the piezoelectric stack;

iii) a horn coupled to the piezoelectric stack, such that the piezoelectric stack is sandwiched between the horn and the inhomogeneous resonator, and where the horn has a cross section distal to the piezoelectric stack that is smaller than a cross section proximal to the piezoelectric stack; and

iv) an end effector coupled to the horn, wherein the end effector couples torsional mode or longitudinal-torsional mode vibrations to a solid or fluid medium.

14. The piezoelectric transducer system of claim 13, further comprising one or more grooves in a surface region of the system for mounting or holding the transducer system in a housing.

15. The piezoelectric transducer system of claim 14, further comprising a housing.

16. The piezoelectric transducer system of claim 15, further comprising a spring frictional engaged between the groove and the housing.

17. The piezoelectric transducer system of claim 16, wherein the spring is a metal coil spring.

18. The piezoelectric transducer system of claim 16, wherein the spring is a Bal Seal canted coil spring.

19. The piezoelectric transducer system of claim 16, wherein the spring is encapsulated in an elastomer or plastic material.

20. A method of mounting a housing on a piezoelectric transducer system comprising frictionally engaging a spring between the transducer system and the housing.