ELECTRONIC ATHLETIC EQUIPMENT

Abstract: A tennis racquet or other athletic instrument configured for striking a movable ball or other playing element includes electronic sensors (90, 92, 96, 98) for providing an audible indication of the location on the racquet or instrument at which contact is made with the ball or other playing element. Various devices for sensing the location of contact are disclosed.

Description: ELECTRONIC ATHLETIC EQUIPMENT Technical Field In recent years, public interest in competitive sporting activities has increased substantially. Not only are more individuals watching popular spectator sports such as football, baseball and basketball; but also, more and more people are becoming actively involved in regularly playing a large number of competitive sports. Where more and more individuals are actually playing or attempting to play a particular sport, increased interest is frequently noticed in the problems of how to learn to play; how to improve one's acquired ability to play; and how to avoid any injury to oneself due to play. Considerable basic skills must be acquired by the novice player in most sports, without which proficiency at the game usually suf¬ fers and physical injury may result. For example, in the game of tennis a proper grip on the racquet is necessary to enable the player to deliver optimum force to the ball when striking it and to prevent the player from injuring a hand or wrist due to reactive forces generated when the ball is struck. Also, the location on the strung portion of the racquet at which the ball is struck plays an important role. If the racquet is held with the plane of its strings approximately perpendicular to the path of the racquet as it approaches the ball and if the ball strikes the racquet in approximately the center of the strung area, then the ball will leave the racquet with optimum velocity and the racquet will not twist in the player's hand. However, if the ball strikes the racquet at a location spaced from the center of the strung area, the racquet usually will twist the player's hand about the wrist or snap the hand back toward the elbow, so that the ball leaves the racquet at an undesired angle and less than optimum speed. Another serious effect of such improper hitting of a tennis ball is that the repeated twist¬ ing of the arm and snapping of the wrist frequently lead to the injury commonly known as "tennis elbow". Thus, tennis players and coaches have long sought a device or technique for reliably training players to hit the ball consistently in the center or "sweet" part of the strung area, both to improve their game performance and to minimize the likelihoo of injury. In other sports where a ball or other playing or game element is struck by some sort of club, bat, racquet or similar athletic instrument, players also seek to strike the game element with a preferred portion of the instrument at which an optimum "hit" is obtained without undesirable side effects on the player. In addition to tennis, games such as golf, jai lai, ping pong, badminton, baseball, polo, softbal lacrosse, cricket and hockey, all involve the use of an athletic instrument for striking a ball or game element. In each case, the location on the instrument at which contact is made greatly affects the resultant movement of the game element and the reactive force transmitted to the player. Under these conditions, it is apparent that a need exists for a device or means which will enable a player to know immediately whether the ball or game element has been struck with the proper portion of the athletic instrument. This type of prompt feedback enables the player to correct his swing accordingly. Such a device would facilitate the training of new players and would enable experienced players to improve their game considerably. BACKGROUND ART Various efforts have been made to assist a player in learning to hit a ball or game element with the proper portio of the athletic instrument. For example, U. S. Patent No. 976,176 discloses a golf club having a detonating cap which explodes when the ball is properly struck. U. S. Patent Nos. 1,928,583 and 2,047,744 show ball paddles having a bell which rings when the ball is struck. U. S. Patent No. 2,214,356 shows a golf club having an impact force indicator. U. S. Patent No. 3,820,785 shows a practice tennis racquet on which only the central section of the racquet is exposed for striking the ball. U. S. Patent No. 3,945,646 shows an OM WI instrumented golf club which measures club head position, velocity and acceleration. U. S. Patent Nos. 4,026,239 and 4,090,707 disclose mechanical tennis teaching aids which are attached to the racquet to emit a sound when the ball is struck properly. Finally, applicants' U. S. Patent No. 4,101,132 discloses a variety of types of electronic tennis racquets. DISCLOSURE OF THE INVENTION The invention provides an improved tennis racquet or other athletic instrument having means for detecting contact or proximity of a ball or game element at preselected locations on the racquet and for indicating the contact or proximity to the player. The invention provides such a racquet or athletic instrument in which the detecting means are small, durable and light weight and are disposed on the racquet or athletic instrument so as not to interfere with its use during play. Other desirable objects achieved or advantages ob¬ tained by the invention may be perceived by those skilled in the art. Nonetheless, the scope of the invention is to be limited only by the appended claims. In one embodiment the inventioncomprises an athletic in¬ strument such as a racquet, bat, club, stick or the like for striking a moveable game element such as a ball, puck, shuttle cock or the like. The athletic instrument includes an area thereon in which contact with the game element is intended to be ma * de during practice or play. Mounted on the athletic instrument are sensing devices for detecting contact or proxi¬ mity of the game element at a preselected location or locations within the intended contact area. Preselected location or locations are rendered electrically conductive such as by coating or impregnating with an electrically conductive coating. Means are also provided on the athletic instrument for giving the player a positive indication, such as an audible signal, when the game element is struck at one of the pre- selected locations. BRIEF DESCRIPTION OF THE. DRAWINGS FIGURE 1 shows a fragmentary view of the strung porti of a tennis racquet embodying resistance or capacitance chang sensors. FIGURE 2 shows a block diagram of a resistance change detection and indication circuit for use with the sensor of Figures 1 and 8. FIGURE 3 shows a block diagram of a capacitance chang detection and indication circuit for use with the sensors of Figures 1 and 8. FIGURE 4 shows a fragmentary view of the strung porti of a tennis racquet embodying capacitive phase angle change sensors. FIGURE 5 shows a block diagram of a detection and indication circuit for use with the sensor of Figure 4. FIGURE 6 shows a fragmentary view of the strung porti of a tennis racquet embodying piezo element sensors. FIGURE 7 shows a block diagram of a detection and in¬ dication circuit for use with the sensor of Figure 6. FIGURE 8 shows a plan view of a tennis racquet em¬ bodying a sensor made from an electrically conductive coating or impregnation as taught by the present invention. ■ BEST MODE FOR CARRYING OUT THE INVENTION There follows, a detailed description of the invention, reference being made to the drawings in which like reference numerals identify like elements of structure in each of the several Figures. Figure 1 shows a fragmentary sectional view of the strung area of tennis racquet embodying a resistance or capacitance type of ball detector. A pair of fine wire leads 90 and 92 are wound about strings 14, with the lead ends spac a distance approximately equal to the string spacing on the racquet. Threads 94 may be used to secure wires 90 and 92, or other attachment means compatible with strings 14, such as epoxy cement. The lead ends of wires 90 and 92 terminate in small contact elements such as spherical elements 96 and 98 which may be applied by welding or soldering. When a ball strikes strings 14 in the vicinity of wires 90 and 92 so that the ball bridges the gap between contacts 96 and 98, the electrical characteristics of the circuit thus formed are altered, thereby providing an indication of ball contact. Other conductive means such as a conductive coating on or an impregnation into strings 14 may be used in lieu of wires 90 and 92. See Figure 8, for example. Figure 2 shows a block diagram of a circuit adapted to measure a change in resistance or resistivity between con- tacts 96 and 98. For an application when three preselected areas are to be monitored during play, resistance change detectors 100, 102 and 104 are provided, which produce a logic "no" when the resistance between contacts 96 and 98 is above a preselected limit, and a logic "yes" when the resistance drops to a predetermined level indicative of a ball bridging elements 96 and 98. Resistance measuring .circuits of the type suitable for this purpose are shown in the chapter 6 of Guide¬ book to Electronic Circuits by John Markus, McGraw-Hill Book Company (New York, 1974) . A conventional tennis ball may be used for this embodiment; however, the sensitivity is improved if the ball is coated lightly with a conductive paint or provided with a conductive surface as shown in U. S. Patent No. 3,854,719 and No. 4,071,242. The outputs of detectors 100, 102 and 104 are supplied to an OR gate 106. When gate 106 receives a "yes" input, it produces an output to a timer 108 and to tri-state switch 110, or similar device, which puts out a logic "no" if the signal from gate 106 is a "no" and a "yes" if the signal from gate 106 is a "yes". Timer 108 puts out a signal as soon as switch 110 has produced its "yes" or "no" output. The signal from timer 108 starts timer 112 and actuates tri-state switch 114. When switch 114 has produced its output, timer 112 actuates tri-state switch 116. The "yes"- no-no", "no-yes-no" or "no-no-yes" outputs of switches 110, 114 and 116 are supplied in series to beeper 118 to produce a tone sequence indicative of the area of ball contact. Failure to bridge one of the contact pairs results in no tone signal at all. The circuit resets itself for the next ball. The circuit illustrated in Figure 2 is also suitable for use with the embodiment of the invention shown in Figure 8. Referring to Figure 8, the strung area of the racquet is shown to be impregnated and/or coated with an electrically conductive coating composition at a preselected location or locations for detecting contact or proximity of the game element at a preselected location or locations within the intended contact area. Although Figure 8 illustrates impreg nating or coating the strung area in the "sweet spot", it is understood that other locations can be impregnated or coated such as all of the strung area except for the "sweet spot". s shown, at least one string in the north-south direction and one in the east-west direction are connected electricall to different terminals of the circuit. This can be achieved, by extending the electrically conductive coating of at least one.string in each axis all the way to the frame, and then either coating the frame from the strings or leading an electrical conducting wire from the strings to the respectiv terminals of the circuit. Any coating can be employed as long as it is suffi¬ ciently electrically conductive for detecting a change in electrical properties and will impregnate and/or coat the strings. Electrically conductive coatings are well known and need not be described herein in any great detail. An example of a suitable conductive coating especially for nylo strings is available from E. I. Du Pont de Nemours under the trade designation "Hypalon-20" (a chlorosulfonated poly¬ ethylene) containing Vulcan XE (an oil furnace carbon black) The thickness of the coating emp_lσyed can vary greatly and need only be thick enough that sufficient current flows ther through so that a change in electrical properties is detecta with the circuitry employed. Thicknesses of about .003 cm. about .25 cm are suitable. When a ball strikes at least two strings in the coated or impregnated area, the electrical characteristics such as the resistance to the current flowing through the coating are changed due to the striking of the ball on the coated or impregnated area, the bridging of a pair of contacts by the ball, or a combination of striking and bridging. This change is then detected by the circuit shown in Figure 2 and an appropriate signal is generated. Figure 3 shows another form of detection and indica¬ tion circuit which may be used with the contact arrangement shown in Figures1 and 8. Instead of detecting a change in the resistance between contacts 96 and 98, a change in capacitance is monitored by capacitance change detectors 120, 122, and 124. Such devices are shown in Chapter 13 of Guide book of Electronic Circuits by John Markus, McGraw-Hill Book Company (New York, 1974) . The outputs of these detectors are processed in a manner identical to that discussed with regard to Figure 2. Figure 4 shows a fragmentary sectional view of a tennis racquet embodying the capacitive phase angle detector. This type of detector comprises a single wire lead 125 which is wound around strings 14, with a small, metallic plate 127 about0.635 cm. by 0.635 cm soldered or welded to the end of lead 120. Plate 127 is located on strings at a place where a ball contact is to be monitored. When an A-C voltage is impressed on lead 125, plate 127 generates a certain field in the surrounding air. When the dielectric characteristics of the surrounding air change substantially, such as when a ball contacts plate 127, the capacitive phase angle of the circuit changes. This change is monitored to provide an indication of when ball contact has occurred. Figure 5 shows a block diagram of a circuit which may be used with the capacitive plate 122 shown in Figure 4. For an application where three preselected areas are to be moni¬ tored during play, capacitive phase angle change detectors 126, 128, and 129 are provided which produce a logic "no" when the capacitive phase angle of plate 127 is within pre¬ selected limits, and a logic "yes" when the phase angle changes by a predetermined amount. Such devices also are shown in Chapter 13 of Guidebook of Electronic Circuits by John Markus, McGraw-Hill Book Company (New York, 1974) . The outputs of detectors 126, 128, and 129 are processed in a manner identical to that discussed with regard to Figures 2 and 3. Figure 6 shows a fragmentary sectional view of a tennis racquet embodying the piezo element detector. This type of detector comprises a pair of wire leads 130 and 132 wound around strings 14 and connected to a piezo element 134. Element 134 preferably is located between strings 14 at an intersection thereof, and may be either a piezo electric or piezo resistive element. When a ball strikes strings 14 in close proximity to the location of element 134, the stress induced in the element produces a voltage or resistance chan depending on the type of element 134 in use. This change is monitored to indicate ball contact in the area. Figure 7 shows a block diagram of a circuit which may be used with the piezo element detector shown in Figure 6. For an application where these preselected areas are to be monitored during play, resistance or voltage change detectors 136, 138 and 140 are used. Those skilled in the art will realize that different circuits are used to monitor resistance and voltage changes; however, for simplicity in the drawing both types of circuits are represented by elemen 136, 138 and 140. Chapters 49 and 64 of the Markus guide¬ book mentioned previously herein show typical resistance and voltage measuring circuits suitable for use in this embodime Detectors 136, 138 and 140 produce.a logic "no" when the characteristics of element 134 are within preselected limits, and a logic "yes" when the characteristics change by a pre¬ determined amount. The outputs of defectors 136, 138 and 140 are processed in a manner identical to that discussed with regard to Figures 2, 3 and 5. INDUSTRIAL APPLICABILITY While the invention has been disclosed for applicatio to a tennis racquet, those skilled in the art will understan O that the principles thereof are applicable to many other fields of sport where the point of contact Q f a ball or similar game element with a bat, racquet or other athletic instrument is important to ensure that the ball is propelled away in the desired direction, with optimum velocity and minimum shock transmission to the player. Particularly in such fields of sport, maintaining eye contact with the ball or playing element is of utmost importance. "Learning to see the ball consistently is the most important art in tennis at all levels of play". Tennis Gazette, Volume 1, No. 4, November- December 1975, "Oh Say Can You SEE" by W. Timothy Gallway, pp. 10-11. Use of a tennis racquet according to this invention will enable the player to know immediately whether eye contact has been maintained and a proper hit made. Having described our invention in sufficient detail to enable those skilled in the art to make and us,e it, we claim: OMPl . wιpo ,*

Claims: WHAT IS CLAIMED IS: 1. An instrument for striking a movable game element to impart motion thereto, comprising: (a) an area on said instrument in which contact with said game element is intended to be mad (b) first means mounted on said instrument comprising at least one electrically conduc¬ tive location to be contacted by the game element, for detecting the presence of the game element relative to said instrument at said at least one location within said area; (c) second means responsive to changes in the electrical characteristics of said first means for providing an indication of the location at which the presence of said game element has been detected. 2. The combination of claim 1 wherein repeated de¬ tections of said game element may be indicated wi'thout re¬ quiring intervention by a player using said instrument or by any other person. 3. The combination of claim 1 wherein said at least one location is rendered electrically conductive by coating impregnating or. coating and impregnating at least a portion of said location with an electrically conductive composition 4. The combination of claim 1 wherein said instrumen is a racquet and said first means detects the presence of said game element on either side of said racquet. 5. The combination of claim 1 wherein said second means comprises an audible signal generator. 6. The combination of claim 1 wherein said first means generates a signal upon a predetermined change in the electrical resistance in said at least one electrically conductive location. 7. The combination of claim 1 wherein said first mea generates a signal upon a predetermined change in electrical capacitance at said at least one electrically conductive location. 8. The invention substantially shown and described.

Inventors: CONREY R, MCQUAID P, YURSIS P
Applicants: CONREY R, MCQUAID P
Application year: 1979
Main classification: A63B69
IPC codes: A63B24, A63B49, A63B69, A63B71