VIBRATION REDUCING GOLF CLUB

Abstract

A vibration reducing golf club includes a club main structure and a plurality of piezoelectric materials. The club main structure includes a club shaft and a ball head and can sustain the mechanical energy resulting from the swing of the club shaft and the collision between the ball head and a golf ball and consequently produces vibration and bending deformation. The piezoelectric materials are connected with conductive wires and adhered to the club shaft. When the club shaft undergoes mechanical deformation, the piezoelectric materials can transform the energy of mechanical deformation into electrical energy, thereby producing a voltage output and then feeding the voltage back to another piezoelectric material, so as to produce a deformation against the vibration direction of the club shaft. Thus, the vibration energy of the club shaft can be consumed. Therefore, the vibration reducing performance can be obtained by reducing the vibration of the club shaft.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 97109127, filed Mar. 14, 2008. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a vibration reducing golf club.

2. Description of Related Art

Along with the progress of technology, material culture and life quality are gradually improved, and sports and leisure activities become fashionable. Golf, used to be a noble game played by nobility, is popularized therewith. More and more people of all age groups and different genders get involved in the golf game, and most of them are golf lovers. Currently, the number of people involved in the golf is increasing abruptly.

In Taiwan area, the number of manufacturers of the golf equipments grows increasingly, and the techniques and export amounts are progressively improved. In recent years, manufacturers of the golf club continuously bring in new materials and new techniques to improve the quality and accelerate the production of the golf clubs. Among the golf clubs, the carbon fiber golf club, made of a composite material and characterized by “light, thin, elastic, and flexible” etc., is developed and gradually warmly welcomed by the international market. Many manufacturers accept the appointments from the international famous sports brand to manufacture and supply the golf equipments, and become one of the world's largest exporters.

In the golf game, in addition to the techniques and stability, properties of the golf clubs are also one of the factors determining the win or lose of a game. As the golfers pay more attention to the feeling of golf swing, the design and fabrication of the golf clubs increasingly become important. Therefore, the manufacturers are trying hard to provide the golfers a better design of the golf equipments with higher performance.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to provide a vibration reducing golf club, so as to achieve the effect of controlling the vibration of the golf club.

The present invention provides a vibration reducing golf club, which includes a club main structure and a plurality of piezoelectric materials. The club main structure includes a club shaft and a ball head. The club main structure can sustain the mechanical energy resulting from the swing of the club shaft and collision between the ball head and a golf ball and produces bending deformation and vibration. The piezoelectric materials are adhered to the club shaft. When the club shaft undergoes mechanical deformation, the piezoelectric materials transform the energy of mechanical deformation into an electrical energy, thereby producing a voltage output. Thus, the vibration energy of the club shaft can be consumed. Therefore, the vibration reducing performance can be obtained by reducing the vibration of the club shaft.

The vibration reducing golf club in the present invention further includes a control module and an energy storage module. The control module includes a conductive circuit configuration and a control circuit configuration. The conductive circuit configuration cross-connects the piezoelectric materials. The control circuit configuration is used to control the voltage output and transmission after one of the piezoelectric materials transforms the mechanical energy into an electrical energy, and to apply the produced electrical energy to another piezoelectric material, so as to transform the electrical energy into the mechanical energy. The energy storage module is used to provide the electrical energy required by the control module.

In the present invention, the piezoelectric materials are adhered to the club, and produce the electromechanical coupling effect to achieve the effect of controlling the vibration of the golf club. Further, the energy storage device may be added to store the piezoelectric energy transformed by the piezoelectric materials. In addition, the present invention utilizes a converse piezoelectric effect of the piezoelectric materials to transform the electrical energy into the mechanical energy, so as to release a power in forward direction of the collision, thereby enhancing the force for hitting a golf ball. After the collision, a force in opposite direction of the vibration of the club shaft is released by the converse piezoelectric effect of the piezoelectric materials, so as to resist and consume the vibration of the club shaft, thereby achieving better vibration reducing effect.

In order to the make aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1A is a schematic structural view of a vibration reducing golf club according to a first embodiment of the present invention.

FIG. 1B is a partial cross-sectional view of FIG. 1A.

FIGS. 1C and 1D are schematic views showing wire connections of the piezoelectric materials of the vibration reducing golf club according to the first embodiment.

FIG. 2 is a curve diagram showing vibration velocity and frequency response taken at an 80 cm position from a tip on a club shaft of the vibration reducing golf club according to the first embodiment.

FIG. 3 is a schematic structural view of an intelligent golf club according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of an energy storage device of the intelligent golf club according to the second embodiment.

FIG. 5 is a schematic view showing a feedback vibration reducing system of the intelligent golf club according to the second embodiment.

FIG. 6 is a schematic view showing a conductive circuit configuration of the intelligent golf club according to the second embodiment.

FIG. 7 is a schematic view showing manufacturing processes of an inner adhering piezoelectric material according to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

FIG. 1A is a schematic structural view of a vibration reducing golf club according to a first embodiment of the present invention. FIG. 1B is a partial cross-sectional view of FIG. 1A.

Referring to FIGS. 1A and 1B, the vibration reducing golf club 100 of the first embodiment includes a club main structure 102 and a plurality of piezoelectric materials 104a, 104b, 104c, and 104d. The piezoelectric materials 104a, 104b, 104c, and 104d may be a single crystal piezoelectric material, such as quartz, lithium niobate, and lithium tantalate; a thin film piezoelectric material, such as zinc oxide; a polymer piezoelectric material, such as polyvinylidene difluoride (PVDF); a ceramic piezoelectric material, such as barium titanate and lead zirconate-titanate; and any combinations of the above materials, and preferably the ceramic piezoelectric material. The club main structure 102 includes a club shaft 106 and a ball head 108. The club shaft 106 is, for example, an iron shaft, a wood shaft, or a composite material shaft (for example, a carbon fiber club). The club main structure 102 can sustain the mechanical energy resulting from the swing of the club shaft 106 and the collision between the ball head 108 and a golf ball (not shown), and produces vibration and bending deformation. The piezoelectric materials 104a, 104b, 104c, and 104d are connected in parallel and adhered to the club shaft 106, and the wire connection manner is shown in FIGS. 1C and 1D.

FIGS. 1C and 1D are schematic views showing wire connections of the piezoelectric materials of the vibration reducing golf club according to the first embodiment. In the figures, only the club shaft 106 and the piezoelectric materials 104a and 104c disposed correspondingly are shown. If the polarities of the sides of the piezoelectric materials 104a and 104c facing the club shaft 106 are positive and negative respectively, this arrangement direction is referred to as forward direction (as shown in FIG. 1C). If the polarities of the sides are both negative, this arrangement direction is referred to as reverse direction (as shown in FIG. 1D). When swinging the golf club (equivalent to that the club shaft 106 undergoes the mechanical deformation), the piezoelectric materials 104a and 104c function as sensors for sensing the deformation of the club shaft 106, so as to transform the energy of mechanical deformation into the electrical energy, thereby producing a voltage output (i.e. the direct piezoelectric effect). Thus, the piezoelectric materials 104a and 104c on two sides of the club shaft are polarized. When the piezoelectric materials 104a and 104c adhered to the two sides of the club shaft 106 have the same polarities, the polarization directions are the same. Therefore, if the piezoelectric material 104a and another piezoelectric material 104c are cross-connected with their positive electrodes connected and their negative electrodes connected respectively, a voltage feedback is generated therebetween, which is equivalent to connecting the piezoelectric materials 104a and 104c in parallel. The piezoelectric material 104a is an actuator, the produced voltage makes the corresponding piezoelectric material 104c to produce the opposite deformation, thereby achieving the effect of controlling vibration.

FIG. 2 is a curve diagram showing vibration velocity and frequency response taken at an 80 cm position (centre of the piezoelectric material) from a tip on a club shaft. The velocity in the vibration velocity response diagram is in the unit of dBm/s, and the value may be converted by the following equation:

dBv=20 log₁₀(v)

where v is the vibration velocity at the measuring point of the club, and dBv is the vibration velocity after being converted into the log dimension. It is apparent from FIG. 2 that the amplitude of the vibration of the vibration reducing golf club having the piezoelectric materials with their wires cross-connected in parallel is further reduced as compared with that without the wires cross-connected in parallel.

In the first embodiment, the piezoelectric materials of the vibration reducing golf club may also be adhered at the following positions on the club shaft.

1. The piezoelectric materials may be adhered at positions in a larger deformation region of the resonant frequency mode of the club shaft in the desired vibration reducing frequency scope, so as obtain better vibration reducing effect. The larger deformation region of the club shaft varies according to different resonant frequencies. Therefore, the piezoelectric materials may be adhered in several regions.

2. The piezoelectric materials may also be adhered to an outer surface of the club shaft or to an inner tube wall of the club shaft as required.

3. The piezoelectric materials may be a combination of several units adhered to the club shaft along its axis as required.

4. The piezoelectric materials may be adhered to the club shaft along its axes at different angles as required. The polarities of the piezoelectric materials adhered to the club shaft along its axes at different angles are arranged in forward direction or reverse direction.

5. The piezoelectric materials may be embedded in grooves of the club shaft as required.

6. When the club shaft is a composite material shaft, the piezoelectric materials may be encapsulated by a lamination layer of the composite material shaft as required.

To sum up, the position where the piezoelectric materials are adhered may be one selected from one or any combinations of the above positions.

FIG. 3 is a schematic structural view of a vibration reducing golf club according to a second embodiment of the present invention.

Referring to FIG. 3, the vibration reducing golf club 300 of the second embodiment includes a club main structure 302, a plurality of piezoelectric materials 304, a control module 306, and an energy storage module 308. The materials of the piezoelectric materials 304 may be selected similarly to the maimer discussed in the first embodiment. The club main structure 302 includes a club shaft 310 and a ball head 312. The club main stricture 302 can sustain the mechanical energy resulting from the swing of the club shaft 310 and the collision between the ball head 312 and a golf ball (not shown), and produces bending deformation and vibration. The selection of the club 310 can refer to that of the first embodiment. The piezoelectric materials 304 are adhered on the club shaft 310. When the club shaft 310 undergoes the mechanical deformation, the piezoelectric materials 304 transform the energy of mechanical deformation into the electrical energy, thereby producing a voltage output (the piezoelectric materials are referred to as the piezoelectric sensors herein). When the piezoelectric materials 304 undergo the electrical energy load, the piezoelectric materials 304 transforms the electrical energy into-the mechanical deformation output (the piezoelectric materials are referred to as the piezoelectric actuators herein). The positions of the piezoelectric materials 304 adhered to the club shaft 310 of the vibration reducing golf club are similar to those discussed in the first embodiment. Further, only the connection relation between the control module 306, the energy storage module 308 and the piezoelectric materials 304 is shown in FIG. 3, which should not considered as indicating the practical positions of them in the vibration reducing golf club 300. The energy storage module 308 is used to provide the electrical energy required by the control module 306. For example, the energy storage module 306 may be a battery or an energy storage device that stores the electrical energy output by the piezoelectric materials 304 into a rechargeable cell, as shown in FIG. 4.

FIG. 4 is a circuit diagram of an energy storage device of the vibration reducing golf club according to the second embodiment. The same reference numbers used in FIGS. 3 and 4 refer to the same parts. Referring to FIG. 4, the energy storage device 400 includes a rectifier circuit 401, a capacitor 402, and a rechargeable cell 403. The piezoelectric materials 304 transform the mechanical energy into the electrical energy under the direct piezoelectric effect, thereby producing a voltage output. The voltage is applied across a rectifier circuit 401, for example a bridge diode, and is rectified to a direct current, and then output to the capacitor 402. The electrical energy may be first charged in the capacitor 402, and finally output and stored in the rechargeable cell 403. The capacitance of the capacitor 402 must match the input voltage, and the rechargeable cell 403 may be nickel-hydrogen cell, lithium cell, or any other rechargeable cell. The energy storage device 400 may be used to store the electrical energy transformed by the piezoelectric materials 304 during the swing of the club into the rechargeable cell 403, and the stored electrical energy may be used in the subsequent control and reducing of the vibration.

FIG. 5 is a schematic view showing a feedback vibration reducing system of the vibration reducing golf club according to the second embodiment. In FIG. 5, the energy storage device is omitted. Referring to FIG. 5, the control module 306 includes a conductive circuit configuration 500 and a control circuit configuration 501. The conductive circuit configuration 500 cross-connects the piezoelectric materials 304. The control circuit configuration 501 is used to control the voltage output and transmission after one of the piezoelectric materials (sensors) 304 transforms the mechanical energy into an electrical energy, and to apply the produced electrical energy to another piezoelectric material (actuator) 304, so as to transform the electrical energy into the mechanical energy. In addition, the control circuit configuration 501 may also be a vibration control configuration, capable of releasing the voltage stored in the rechargeable cell (403 in FIG. 4) through a control circuit (not shown) after the ball head (312 in FIG. 3) hits the golf ball (not shown), and leading the voltage to the piezoelectric materials (actuators) 304, so as to transform the electrical energy into the mechanical energy, thereby releasing a force to resist the deformation of the club shaft 310. Also, in order to achieve a better vibration reducing effect, the vibration control configuration may further include an amplifier, for amplifying the voltage output by the piezoelectric materials (sensor) 304. In addition, the control circuit configuration 501 can also include a power driving circuit configuration, for releasing a force when the ball head hits the golf ball (not shown), so as to increase the flight kinetic energy of the golf ball. For example, when the piezoelectric materials are deformed to transform the mechanical energy into the electrical energy to produce the voltage output, the power driving circuit triggers the timer to start counting. After a period of time (i.e. starting when the club shaft 310 begins to deform and ending when the club shaft 310 restores and the ball head finishes hitting the golf ball), the voltage stored in a rechargeable cell (403 of FIG. 4) is released through a control circuit, and is led to one of the piezoelectric materials (actuators) 304, such that the electrical energy is transformed into the mechanical energy, so as to output a power to drive the club shaft 310, thereby enhancing an impact force of the ball head 312 when hitting the golf ball.

FIG. 6 is a schematic view showing a conductive circuit configuration of the vibration reducing golf club according to the second embodiment. Referring to FIG. 6, if the polarities of the sides of the piezoelectric materials 304 facing the club shaft 310 are positive and negative respectively, this arrangement direction is referred to as forward direction. If the polarities of the sides are both negative, this arrangement direction is referred to as reverse direction. Therefore, the piezoelectric materials in FIG. 6(a) are connected in parallel in forward direction, the piezoelectric materials in FIG. 6(b) are connected in series in forward direction, the piezoelectric materials in FIG. 6(c) are connected in parallel in opposite directions, and the piezoelectric materials in FIG. 6(d) are connected in series in opposite directions. Therefore, if the piezoelectric materials 304 are connected in parallel, the produced voltage makes corresponding piezoelectric materials to produce opposite deformation tendencies, thereby restraining the original deformation and achieving the vibration reducing effect. On the contrary, if two piezoelectric materials 304 are connected in series, the potential energy of the voltage produced by the two piezoelectric materials may be added, thereby achieving a better energy storage effect. In addition, the conductive circuit configuration may further include a switching switch (not shown), for switching the control circuit configuration (501 in FIG. 5) to the vibration control configuration or the power driving circuit configuration.

The adhesion manner of the piezoelectric materials 304 of the second embodiment may be an outer adhesion, inner adhesion, or encapsulating manner. Among the manners, the outer adhesion and the inner adhesion will not affect the original golf club manufacturing process. In FIG. 7, the piezoelectric materials 304 are adhered, for example, in the inner adhesion manner, which is only an example for fabricating the piezoelectric materials of the second embodiment and is not intended to limit the fabricating method of the structure of the present invention.

FIG. 7 is a schematic view showing manufacturing processes of an inner adhering piezoelectric material according to the second embodiment. Referring to FIG. 7, the composite material of the second embodiment may be formed by six piezoelectric strips 700 having a size of 50 mm*2 mm*0.3 mm, four conductive copper foils 702 having a size of 160 mm*1.5 mm*14 μm, and two glass fiber/epoxy resin prepreg cloths 704 having a size of 160 mm*10 mm. The molds required by the manufacturing process are divided into an inner mold 706 and an outer mold 708. The inner mold 706 is made of a high molecular material, for example, PTFE, Teflon, or any other fluoro polymer material, and has the characteristics such as fine release and high expansion coefficients. The outer diameter of the inner mold 706 equals to the inner tube diameter of the club shaft minus twice the thicknesses of the piezoelectric strips 700, the conductive copper foils 702, and the prepreg cloths 704. The outer mold 708 is a metal mold made of an aluminium or a steel material, and the inner diameter thereof equals to the inner tube diameter of the club shaft.

The manufacturing processes of FIG. 7 are described as follows.

In Step 1, one glass fiber/epoxy-resin prepreg cloth 704 is adhered on a surface of the inner mold 706 made of the fluoro polymer material.

In Step 2, each of the conductive copper foils 702 is respectively adhered at the symmetrical position (0°/180° or 90°/270°).

In Step 3, three piezoelectric strips 700 are placed on each of the conductive copper foils 702.

In Step 4, the conductive copper foils 702 are respectively placed on the piezoelectric strips 700, and an insulating material is coated between the piezoelectric strips 700, so as to isolate the upper and the lower conductive copper foils 702.

In Step 5, one glass fiber/epoxy resin prepreg cloth 704 is adhered to the conductive copper foils 702.

In Step 6, they are encapsulated by one OPP thin film encapsulates, and placed into the outer mold 708 of moulded metal.

In Step 7, the outer mold 708 is placed into a hot press machine, and is pressurized to 2 kg/cm² and heated for 30 minutes in an environment of 135° C.

In Step 8, the outer mold 708 is cooled down, then opened, so as to remove the OPP thin film and take out the inner mold 706, thus obtaining the moulded piezoelectric unit.

In Step 9, a solvent type epoxy adhesive curable at 130° C. is coated on the surface of the piezoelectric unit, and then the piezoelectric unit is laid for the solvent evaporating to dry.

In Step 10, the piezoelectric unit is pushed into the appropriate position in the club shaft by a fixture.

In Step 11, the club is placed into the oven and heated at 135° C. for 30 minutes, thus finishing the assembly processes of the inner adhering piezoelectric materials.

To sum up, the present invention uses the piezoelectric materials to transform the mechanical load into the voltage output, or transform the voltage input into the force output, and thus having the advantages of high piezoelectric constant, quick response, small volume, and no electromagnetic interference, etc. Therefore, when applied to the golf club, the present invention alleviates the vibration resulting from the collision between the golf club and the golf ball, and particularly, the violent vibration caused by failing to hit the sweet spot. In addition, the present invention also employs the control module and the energy storage module to control the piezoelectric materials, so as to achieve a vibration reducing golf club capable of reducing the vibration and/or enhancing the hitting force.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. A vibration reducing golf club, comprising:

a club main structure, comprising a club shaft and a ball head, wherein the club main structure is capable of sustaining a mechanical energy resulting from a swing of the club shaft and collision between the ball head and a golf ball, and produces bending deformation and vibration; and

a plurality of piezoelectric materials, adhered to the club shaft, wherein when the club shaft undergoes mechanical deformation, the piezoelectric materials transform an energy of mechanical deformation into an electrical energy, thereby producing a voltage output, thus consuming vibration energy of the club shaft and obtaining a vibration reducing performance by reducing vibration of the club shaft.

2. The vibration reducing golf club according to claim 1, wherein the plurality of piezoelectric materials comprise connecting in parallel.

3. The vibration reducing golf club according to claim 1, further comprising:

a control module, comprising:

a conductive circuit configuration, cross-connecting the piezoelectric materials; and

a control circuit configuration, for controlling voltage output and transmission after one of the piezoelectric materials transforms the mechanical energy into the electrical energy, and applying the produced electrical energy to another piezoelectric material, so as to transform the electrical energy into the mechanical energy; and

an energy storage module, for providing the electrical energy required by the control module.

4. The vibration reducing golf club according to claim 3, wherein a cross-connect manner of the conductive circuit configuration comprises serial connection or parallel connection.

5. The vibration reducing golf club according to claim 3, wherein the energy storage module comprises a battery or an energy storage device.

6. The vibration reducing golf club according to claim 5, wherein the energy storage device stores the electrical energy output by the piezoelectric materials into a rechargeable cell.

7. The vibration reducing golf club according to claim 6, wherein the energy storage device comprises a rectifier circuit, a capacitor, and the rechargeable cell.

8. The vibration reducing golf club according to claim 6, wherein the control circuit configuration comprises a vibration control configuration, capable of releasing a voltage stored in the rechargeable cell through a control circuit after the ball head hits the golf ball, and leading the voltage to the piezoelectric materials, so as to transform the electrical energy into the mechanical energy, thereby releasing a force to resist the deformation of the club shaft.

9. The vibration reducing golf club according to claim 8, wherein the vibration control configuration further comprises an amplifier, for amplifying the voltage output by one of the piezoelectric materials, and applying the voltage to another piezoelectric material.

10. The vibration reducing golf club according to claim 3, wherein the control circuit configuration further comprises a power driving circuit configuration, for releasing a force when the ball head hits the golf ball, so as to increase a flight kinetic energy of the golf ball.

11. The vibration reducing golf club according to claim 10, wherein the power driving circuit configuration comprises a timer.

12. The vibration reducing golf club according to claim 11, wherein when the piezoelectric materials are deformed to transform the mechanical energy into the electrical energy to produce the voltage output, the power driving circuit configuration triggers the timer to start counting, and after a period of time, the voltage stored in a rechargeable cell is released through a control circuit, and is led to one of the piezoelectric materials, such that the electrical energy is transformed into the mechanical energy, so as to output a power to drive the club shaft, thereby enhancing an impact force of the ball head when hitting the golf ball.

13. The vibration reducing golf club according to claim 12, wherein the period of time when the timer is counting starts when the club shaft begins to deform and ends when the club shaft restores and the ball head finishes hitting the golf ball.

14. The vibration reducing golf club according to claim 3, wherein the conductive circuit configuration further comprises a switching switch, for switching the control circuit configuration to a vibration control configuration or a power driving circuit configuration.

15. The vibration reducing golf club according to claim 1, wherein a position of the piezoelectric materials adhered to the club shaft is one selected from a deformation region of a resonant frequency mode of the club shaft in a vibration reducing frequency scope, so as to obtain the vibration reducing effect.

16. The vibration reducing golf club according to claim 15, wherein the position of the piezoelectric materials adhered to the club shaft comprises several regions.

17. The vibration reducing golf club according to claim 1, wherein the piezoelectric materials comprise a combination of a plurality of units adhered to the club shaft along its axis.

18. The vibration reducing golf club according to claim 1, wherein one of the piezoelectric materials is adhered to the club shaft along its axis, and anther piezoelectric material is adhered to a corresponding other side of the club shaft.

19. The vibration reducing golf club according to claim 18, wherein polarities of the piezoelectric materials adhered to two sides of the club shaft are arranged in same or opposite directions.

20. The vibration reducing golf club according to claim 1, wherein the piezoelectric materials are adhered to the club shaft along its axes at different angles.

21. The vibration reducing golf club according to claim 20, wherein polarities of the piezoelectric materials adhered to the club shaft along its axes at different angles are arranged in same or opposite directions.

22. The vibration reducing golf club according to claim 1, wherein the piezoelectric materials are adhered to the club shaft through an outer adhesion manner.

23. The vibration reducing golf club according to claim 1, wherein the club shaft further comprises a plurality of grooves, and the piezoelectric materials are embedded in the grooves.

24. The vibration reducing golf club according to claim 1, wherein the piezoelectric materials are adhered to an inner tube wall of the club shaft through an inner adhesion manner.

25. The vibration reducing golf club according to claim 1, wherein when the club shaft is the composite material shaft, the piezoelectric materials are encapsulated by a lamination layer of the composite material shaft.