Baseball hat

• US 6,086,490 A
• Filed: 04/03/1998
• Issued: 07/11/2000
• Est. Priority Date: 09/29/1995
• Status: Expired due to Term

• Current Assignee: Cymer Incorporated (ASML Holding NV)
• Original Assignee: Active Control eXperts, Inc. (ASML Holding NV)
• Inventors: Jacques, Robert N., Gilbert, David, Bianchini, Emanuele, Spangler, Ronald, Moore, Jeffrey W., Lazarus, Kenneth B., Allen, Jonathan C., Russo, Farla M., Prestia, Carl
• Primary Examiner(s): Chiu, Raleigh W.
• Application Number:
  US09/054,940
• Time in Patent Office: 830 Days
• Field of Search: 473/318, 473/564, 473/558, 473/521, 473/520, 473/523, 210/317, 210/326, 280/602
• US Class Current: 473/564
• CPC Class Codes: A63B 2208/12 specially adapted for children
• CPC Class Codes: A63B 53/00 Golf clubs
• CPC Class Codes: A63B 60/00 Details or accessories of golf clubs, bats, rackets or the like
• CPC Class Codes: A63B 60/54 with means for damping vibrations
• CPC Class Codes: A63C 5/075 Vibration dampers vibration dampers per se F16F7/00

Abstract

A baseball bat includes an electroactive assembly attached near the handle and electrically tuned to capture energy from several modes with high efficiency. More generally, a sports implement includes an electroactive element, such as a piezoceramic sheet attached to the implement, and a circuit attached to the electroactive element. The circuit may be a shunt, or may include processing such as amplification and phase control to apply a driving signal which may compensate for strain sensed in the implement, or may simply alter the stiffness to affect performance. In a ski, the electroactive element is located near to the root in a region of high strain to apply damping, and the element captures between about one and five percent of the strain energy of the ski. The region of high strain may be found by modeling mechanics of the sports implement, or may be located by empirically mapping the strain distribution which occurs during use of the implement. In other embodiments, the electroactive elements may remove resonances, adapt performance to different situations, or enhance handling or comfort of the implement. Other embodiments include striking implements intended to hit a ball or object in play, such as mallets, golf clubs and tennis racquets, wherein the strain elements may alter the performance, feel or comfort of the implement. The electroactive elements may be configured in sets to capture energy in different modes, and/or along different directions.

Claims

1. A sports implement comprising

a body having an extent and including a contact surface which is subject in use to stimulation such that the body vibrates with a distribution of strain energy in said body including a region of strain

an electroactive assembly including an electroactive strain element for transducing electrical energy and mechanical strain energy, said electroactive assembly being attached to said body in said region of strain, and

circuit across said assembly configured to dissipate said electrical energy and damp vibration of the body,

wherein said sports implement is a baseball bat.

2. A baseball bat according to claim 1, wherein said stimulation excites structural modes of said body giving rise to said strain distribution, and said assembly and circuit shift or damp excitation of modes to improve handling of the bat.

3. A baseball bat according to claim 1, wherein said strain distribution includes an area of high strain and said assembly is coupled by a substantially shear free coupling to said area of high strain.

4. A baseball bat according to claim 1, wherein said electroactive assembly is attached near the handle and away from the contact surface.

5. A baseball bat according to claim 1, wherein the electroactive assembly includes plural regions of separately-electroded piezo material.

6. A baseball bat according to claim 5, wherein the separate regions are configured to damp distinct modes of the bat.

7. A baseball bat according to claim 1, wherein said circuit is enclosed in the body.

8. A baseball bat according to claim 1, comprising an LED indicator in electrical communication with said electroactive assembly.

9. A baseball bat according to claim 1, wherein said electroactive strain element is electro-ceramic.

10. A baseball bat according to claim 1, wherein the bat has a grip forming a mechanical root of the bat.

11. A baseball bat according to claim 1, wherein said circuit is an inductive shunt for dissipating charge generated by strain coupled from said region of strain into said element.

12. A baseball bat according to claim 1, wherein said strain element is covered by cushioning material.

13. A baseball bat according to claim 1, wherein said bat is a metal bat and the strain element is attached by a substantially shear free coupling to said body for coupling in-plane strain energy therebetween.

14. A baseball bat according to claim 1, wherein said electroactive assembly is a curved assembly fitted to the bat.

15. A baseball bat according to claim 14, wherein said electroactive assembly is a flexible assembly formed as a sheet with relief cuts for conforming to the bat.

16. A baseball bat according to claim 1, wherein said assembly includes electroactive material configured to damp vibration occurring along plural different axes.

17. A sports implement according to claim 1, wherein the region of strain includes planar areas and said electroactive assembly is formed as a sheet comformable to said planar areas.

18. A baseball bat having an elongated body with a ball striking end and a grip portion opposed thereto, and a damper attached to said body wherein the damper includes

an assembly of at least one piezoelectric element attached to said elongated body such that the strain is effectively coupled between said body and said assembly, and

a circuit operative to control charge in the assembly and thereby damp the baseball bat.

19. A baseball bat according to claim 18 including at least one LED powered by the assembly to indicate damping operation.

20. A method of damping a baseball bat, such method comprising

strain-coupling an electroactive assembly to a region of the bat located proximate to its grip and away from its striking end to receive strain energy from the bat and produce electrical charge therefrom, and

placing a circuit across the electroactive assembly to shunt the charge and alter strain in said region thereby changing response of the bat.

21. The method of claim 20, wherein the step of placing a circuit includes shunting opposed poles of said electroactive assembly to dissipate energy received from said region.

22. The method of claim 21, wherein said electroactive assembly includes separately-electroded electroactive elements and the step of placing a circuit includes placing separate circuits across subsets of said elements to produce damping.

23. The method of claim 22, wherein the step of strain coupling an assembly to receive strain energy includes mounting the assembly near a mechanical root of said bat implement over a region effective to receive strain energy from said implement and produce damping of at least (0.15) percent.

24. The method of claim 22, wherein the step of strain coupling the electroactive assembly includes bonding a sheet actuator around the handle of the bat.

25. A method of making a damped baseball bat, such method including

the steps of

providing a baseball bat body

adding to the body an electroactive assembly including an electroactive strain element extending along the baseball bat body so as to efficiently couple strain between said element and said body, and

shunting charge generated in said strain element at one or more modal frequencies of the baseball bat.

26. A method of making a damped baseball bat according to claim 25, wherein the steps of adding an electroactive assembly and shunting charge at one or more modal frequencies includes adding separate regions of electroactive material which are shunted to damp distinct modal frequencies of the baseball bat.