An apparatus and method for determining the kinematic characteristics of a golf club head are disclosed. The apparatus includes at least one piezoelectric component selectively positioned within or upon a club head. The piezoelectric component is preferably positioned to the rear of the center of gravity, and near the midpoint of the face of the club head. During a golf club swing, the piezoelectric component determines the acceleration and deceleration of the golf club head. When the club head impacts an object such as a golf ball, the piezoelectric component is also operable to determine the velocity of the club head. It may also be desirable for the piezoelectric component to determine the magnitude of vibration during impact. In this manner, the piezoelectric component may function determine the efficiency of a golf club swing.

[0002] The growing interest in the game of golf has spurred golf equipment manufacturers to increase the variety of equipment that they produce. Revolutions in computing and advances in material science have simultaneously allowed equipment manufacturers to meet the demands of consumers in ever more precise ways. Golf balls, for instance, are now manufactured specifically to give a golfer the right "feel" when the club face strikes the golf ball. Golf balls are also manufactured to fly farther by manipulating the patterns formed by the dimples on the surface of the golf ball. With respect to golf clubs, newer materials have allowed golf club designers to produce lighter and stronger golf clubs. Features of the golf clubs have also been varied to manipulate head characteristics, such as center of mass, face angle, and face texture.

[0003] Depending on the skill of the golfer, their playing style, and their personal preferences, specific equipment may be selected to assist the golfer in obtaining the optimal performance. In the past, a golf professional would assist a golfer in choosing their equipment either based on their body type, general information provided by the golfer about their style of play, and/or observing the golfer's swing with the naked eye. More recently, golf professionals have used devices referred to as "launch monitors" to observe a player's swing characteristics. By observing a golfer's swing with different clubs and balls, a launch monitor provides a golf professional with more information on which to base a club and/or ball recommendation.

[0004] A limitation of present methods and apparatus for measuring the kinematics of a golf club is that the measurements are taken by outside equipment. For instance, a launch monitor often acquires images of a golf club in motion and then determines the kinematic characteristics of the club based on those images. While the precision and accuracy of these devices is constantly improving, it is also desirable to obtain the kinematic characteristics of the golf club from the golf club itself. That is, a continuing need exists for a method and apparatus that allows a golf club to directly measure and relay the kinematic information of the golf club. Moreover, a continuing need exists for a golf club that has the ability to measure and relay its kinematic characteristics without being perceptible to a golfer.

[0005] According to one aspect, the present invention comprises an apparatus for measuring the kinematic characteristics of a golf club. The apparatus includes a golf club head that comprises an inner volume bounded by a face and a rear. A piezoelectric component is selectively positioned within the inner volume towards the rear of the center of gravity of the golf club head and on the back of the face of the golf club head. In one embodiment, the piezoelectric device comprises an accelerometer. It may be desirable for the apparatus to also include a display operatively connected to the piezoelectric component and configured and dimensioned to be part of the golf club head's surface.

[0006] According to this aspect, the present invention also includes a processor and a memory operatively connected to the piezoelectric component. To allow information to be transferred from the piezoelectric component to an outside processor, a wireless transmitter may also be utilized. In order to prevent a golfer from perceiving the piezoelectric component within the club head, it is preferably secured in a desired portion of the inner volume of the club head using a fastener.

[0007] The piezoelectric component is operable to determine several kinematic characteristics, such as the velocity of the golf club head at impact with an object, e.g., a golf ball. In addition, the magnitude of vibration generated during impact with an object, and the linear and rotational acceleration and deceleration of the golf club head may also be determined.

[0008] According to another aspect, the present invention comprises an apparatus for measuring the kinematics of a golf club head. The apparatus includes a golf club head comprising an inner volume formed by a face and a rear. At least two piezoelectric components are selectively positioned within the inner volume of the golf club head such that they are positioned towards the rear of the golf club head. Preferably, a first of the at least two piezoelectric components is positioned substantially midway between the heel and a midpoint of the face of the golf club head, and the second of the at least two piezoelectric components is positioned substantially midway between the midpoint of the face and the toe of the golf club head. Optionally, the at least two piezoelectric components, which may be operatively connected to one another, are positioned towards the rear of the center of gravity of the club head.

[0009] Finally, according to a third aspect of the present invention, a method for measuring the kinematic characteristics of a golf club is disclosed. The method includes selectively positioning an accelerometer within the inner volume of a golf club head. Then, the kinematic characteristics of the golf club head during motion are acquired using the accelerometer. After the kinematic characteristics are acquired, they are preferably displayed.

[0019] It is also desirable for the information acquired by the present invention to be displayed so that a golfer can analyze the kinematic characteristics of their performance. One way to display the information measured and recorded by the accelerometer is to operatively connect a display 22 (FIG. 1), such as an LCD, LED, or other type of display to the accelerometer. In this embodiment, the display is selectively positioned away from the striking surface of the club, e.g., the face of the club. The display may be configured and dimensioned such that it does not obstruct or otherwise affect the movement of the club. It may be desirable to employ a flexible, flat display, such as those developed and manufactured by companies such as Lucent, DuPont, 3M, and Phillips. Using a flexible display allows the display to follow the natural contour of the club head while still allowing a golfer to view the desired information.

[0020] In one embodiment, the display may be configured and dimensioned such that it forms a portion of the golf club head's outer surface, such as the skirt or perimeter of the golf club. Alternately, the display may be positioned on top of a portion of the golf club head. If such a configuration is selected, it is desirable for the display to be adapted such that it does not appreciably affect the aerodynamic qualities of the golf club head. One way that this may be achieved is to secure the display to the golf club head, and then provide a transparent coating or layer over the display to hold it in place. Other methods and/or apparatus known to skilled artisans may also be used to minimize the display's effect on the aerodynamic qualities of the club head.

[0021] Another way to display the information measured and recorded is to include a wireless transmitter 24 that is operatively connected to the accelerometer. The wireless transmitter 24 may be positioned within the inner cavity of the club head, within the inner cavity of the club shaft, or otherwise. The weight of the wireless transmitter 24 is preferably minimized such that it has a negligible effect on the overall weight, or weight distribution, of the golf club. In another embodiment, the information obtained and stored by the present invention may be uploaded to another processor, e.g., a computer, though a manual connection, e.g., a universal service bus connection. The connection may be selectively positioned on any part of the golf club head, or shaft, however it is preferably placed away from the striking surface of the club, e.g., the face.

[0022] It is preferable for the present invention to be positioned, configured, and dimensioned such that it measures the kinematic characteristics of the golf club without being perceived by a golfer. Along these lines, the accelerometer is preferably fastened to at least a portion of the inner volume of the club head. The accelerometer may be fastened to the inner volume of the club head using any method or apparatus known to those skilled in the art, such as glue, epoxy, resin, or mechanical fasteners. For instance, according to one aspect of the invention the accelerometer is fastened to the inner volume of the club head using an insert placed inside the club head. The insert may be comprised of any material, such as urethane or the like. Preferably, the weight of the material used to fasten the accelerometer to the inner volume of the club head is minimized so that its effect on the overall weight and weight distribution of the club head is reduced.

[0023] Any number of accelerometers may be used as desired. As shown in FIG. 1, one accelerometer may be selectively positioned within the inner volume of the club head. The accelerometer is preferably positioned near the midpoint of the face 10 and towards the rear 12 of the club head. It is also desirable for the accelerometer 14 to be positioned to the rear 12 of the center of gravity 16, e.g., between the center of gravity 16 and the rear 12 of the club head. When positioned in this manner, the accelerometer 14 is operable to measure the forces generated by an impact of the club head with a golf ball. If the club head strikes the golf ball in the center of the face (impact 1), the accelerometer 14 will measure only a single force component that is perpendicular to the face 10 because the accelerometer 14 is also positioned at the center of the face. However, when the club head strikes the golf ball off center (impact 2), the accelerometer's 14 position at the center of the club face allows it to measure the various components of the force, e.g., a "side" force, that is generated by the impact.

[0024] In an alternate embodiment, the present invention may include two or more accelerometers 18, 20. As shown in the FIG. 2 embodiment, two accelerometers 18, 20 may also be positioned within the inner cavity of the club head. A first accelerometer 18 may be positioned between the midpoint of the face and the toe of the club, and the second accelerometer 20 may be positioned between the midpoint of the face and the heel of the club, as shown in FIG. 2. With respect to the center of gravity 16 and the rear 12 of the club, each accelerometer 18, 20 is positioned in a similar manner as described above with respect to the embodiment comprising a single accelerometer.

[0025] One advantage of using two or more accelerometers is that the forces generated at different parts of the club head may be measured. For example, if the club head strikes the ball off center (impact 2), as shown in FIG. 2, accelerometer 20 will measure only one force component that is substantially perpendicular to the face 10 of the club because this accelerometer is in line with the impact location on the face. Relative to the position of accelerometer 18, however, the impact will be off center, causing accelerometer 18 to record two or more force components based on the side force that is generated. Thus, one advantage of using two accelerometers 18, 20 is that the area of impact may be more accurately determined relative to the center of the face 10. Moreover, the force components at different parts of the club head may also be determined with a greater degree of accuracy.

[0026] Though it is preferable for the accelerometer to be positioned as described above, the other elements that are operatively connected to the accelerometer may be selectively positioned as desired. That is, elements such as the processor, display, and power supply may be positioned in different areas of the inner volume of the club head. When positioning the other elements, the overall weight distribution of the club head may be taken into account. In other words, the weight of the other elements can be distributed such that the club head has a desired weight distribution, e.g., more weight lower, rear of the club, beneficially positioning the club head center of gravity. Each of these elements may be secured to the inner volume of the club head in a similar manner as those described above with respect to the accelerometer.

[0027] The apparatus of the present invention enables a plurality of kinematic characteristics of the golf club to be determined. For example, the apparatus described above allows characteristics such as acceleration, deceleration, velocity at impact, and acceleration/deceleration through impact to be measured. The present invention is also operable to be used as an efficiency meter. In other words, an accelerometer may be positioned at the center of the club head. When the golf club strikes a golf ball off center, e.g., towards the toe or heel, the accelerometer will record a different signal than if the golf ball was struck at the center of the face. By measuring the amplitude and frequency content of vibration, the efficiency of the golf club swing may be determined.

[0028] A similar principle applies to embodiments that use two or more accelerometers. In the FIG. 2 embodiment, when the club head strikes a golf ball off center, closer to the heel, accelerometer 20 will measure a larger vibration than accelerometer 18. Similarly, when the club head strikes the golf ball off center, closer to the toe, accelerometer 18 will measure a larger vibration than accelerometer 20. Through testing, theoretical maximum and minimum vibrations can be pre-programmed into the memory. This data may be customized to the particular golfer by factoring in the golfer's typical or measured swing speed, as greater swing speeds create greater force, acceleration, and vibration values. By comparing the measured value of a particular swing to the data stored in the memory, the golfer's performance can be quantified and displayed on the screen, giving the golfer instant feedback regarding the swing.

[0029] According to another aspect, the method of the present invention includes swinging the golf club of the present invention. Initially, the club is positioned near the golf ball as a golfer lines up his/her shot, referred to as the initial position. The club goes through three stages with respect to the initial position, commonly referred to as the backswing, the downswing, and the follow-through. During the backswing and downswing, the accelerometer measures the acceleration of the golf club head. Subsequent to impact, i.e., during the follow-through, the accelerometer measures the deceleration of the golf club head. During impact between the golf club head and the golf ball, the velocity of the golf club may be determined. The velocity during impact is determined based on the measured force components, described in detail above. Optionally, the efficiency of the impact may also be determined as described above.

[0030] After a golf swing has been completed, the information may be displayed. Preferably, the information is displayed on a screen 22 (FIG. 1) that is configured and dimensioned to be part of the golf club, as described above. In other embodiments, the stored information may be transmitted to another processor that may display the information. The transfer of information may be wired or wireless. The information, e.g., the acceleration, deceleration, and velocity, is preferably displayed numerically. In a more preferred embodiment, however, a graphical illustration of the acceleration in each stage of the swing may be provided. In embodiments where kinematic information is transferred to an external processor, the information may be analyzed and charts, graphs, or other types of analysis may be performed.

[0031] For instance, the swing speed of the golf club may be measured and displayed. In addition, the acceleration and velocity of the golf club head may be used to calculate the distance and trajectory of the golf ball. Alternately, the present invention may also be combined with other types of electronic monitoring equipment. For instance, the present invention may be used in combination with external launch monitors that measure the kinematic characteristics of both the golf club and the golf ball. The information obtained by the launch monitor may be combined with the kinematic information measured by the present invention in order to measure and display swing speed, ball trajectory and distance, and ball spin. Examples of launch monitors that may be used in combination with the present invention include U.S. patent Ser. Nos. 10/861,443 and 10/898,367, the entireties of which are incorporated herein by reference. The present invention may also be used in combination with other methods and apparatus for measuring the kinematics of both golf equipment and a golfer's body. Examples of such methods and apparatus are disclosed in U.S. patent Ser. Nos. 11/364,343 and 11/524,304, the entireties of which are also incorporated herein by reference.