BACKGROUND OF THE INVENTION Field of the Invention

This invention pertains, in general, to sports and athletic equipment, and in particular, to a device for training and improving racket swing.

Description of Related Art

Racket sports such as tennis, table tennis, squash and badminton have enjoyed an almost universal popularity for many years. These sports activities all have in common the fact that they are games played upon a specialized court upon which a net may be mounted and upon which the players attempt to direct the course of a ball or other object by striking it with a specialized racket.

The racket typically comprises an elongated shaft having a grip at one end for grasping between the player's fingers and an enlarged, generally ovate, planar head part at the other end having a pair of opposing faces with which the ball is struck.

The head of the racket may consist of a solid, or laminated "paddle", such as the type used in paddle tennis and pingpong, or may include an ovate frame member having an opening within which are tightly strung a plurality of interwoven elastic strings, such as in those rackets used in the games of tennis and badminton.

Formerly, a majority of rackets were fabricated primarily from formed pieces of wood which were adhesively joined; however, in recent years, the art has seen many improvements in racket materials and construction, including the use of plastic and metal laminates, carbon-fiber-reinforced materials and hollow- core construction.

During all racket sports, the player is obliged to

control the initial trajectory of the ball solely by striking it with the racket. This activity typically involves a swing of the racket through an arc during which one or the other of the racket's faces is caused to collide with the ball, depending upon whether the swing is a forehand, overhand or backhand swing. Accordingly, much of the success of a player in the sport will depend upon his or her ability to exercise proper control over the racket's swing.

Thus, one of the major problems experienced by beginners and neophytes in racket sports is an inability to control the racket properly during the swing. More particularly, one of the problems experienced by beginning players, as in other sports, is a failure to "follow-through" with the swing, i.e., the failure to continue the swing of the racket through its arc beyond the point at which the racket has contacted the ball, in order to maximize control over the ball's trajectory and the velocity imparted to the ball by the racket. This failure is often largely the product of the player's initial failure to learn the "feel" of the technique of proper follow-through, as well as improperly developed arm muscles, particularly in the wrist and forearm, and such players are frequently characterized as having a "lazy racket".

It is therefore an object of the present invention to provide a racket sports swing trainer capable of aiding a player in developing proper follow-through technique and racket control, as well as developing the strength of the player's muscles employed during the swing. It is a further object of the present invention to provide such a trainer within a device which may be quickly attached and detached to a conventional racket, or alternatively, provided integrally of a complete and functional training racket.

SUMMARY OF THE INVENTION These objectives are preferably accomplished in one embodiment by the provision, within a device adapted for attachment to a conventional sports racket, of a pair of weights of about equal mass which are disposed in a first position symmetrically on opposite sides of, co- planar with, and generally central of, the head of the racket, and constrained to move, during a swing of the racket, smoothly and symmetrically from the first position and toward a second position at the racket's crown along a path generally parallel, contiguous, co¬ extensive and co-planar with an upper portion of the head's outer radial periphery, along with means for confining the weights' movement along the path during the swing, means for biasing the weights generally equally toward the first position after the swing, and ^• means for quickly attaching and detaching the device to the head without substantially obscuring either of the rackets' faces or the necessity of substantially modifying the racket to attach the device.

In a narrower embodiment, the training device is incorporated integrally of a racket which may be used for both training and normal play.

These, and other objects and advantages of the present invention will become more readily evident to those skilled in the art from a consideration of the following detailed description of the preferred embodiments, particularly when considered in conjunction with the attached drawings, a brief description of which now follows.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an illustration of a racket sports player engaged in a forehand swing of a tennis racket which incorporates a device in keeping with the instant

invention;

Fig. 2 is a more detailed view into the face of the head of a strung racket incorporating a first exemplary embodiment of the device and within which a sectional view III-III is taken;

Fig. 3 is a detailed cross-sectional view through the first exemplary embodiment, as revealed by the Section III-III taken in Fig. 2;

Fig. 4 is a partial detailed view into the face of a strung racket incorporating a second exemplary preferred embodiment of the device;

Fig. 5 is yet another partial detailed view into the face of a racket incorporating an alternative third exemplary preferred embodiment of the present invention and within which a sectional view VI-VI is taken;

Fig. 6 is a detailed sectional view through the device as revealed by the Section VI-VI taken in Fig. 5; and

Fig. 7 is a detailed cross-sectional view through a racket incorporating a device in keeping with the present invention illustrating alternative attachment means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 illustrates a racket sports player engaged in swinging a racket 1 equipped with a device 10 of the present invention toward a ball, and in the case illustrated, is illustrative of a tennis racket and ball.

In a majority of racket sports, racket 1 typically comprises an elongated shaft 2 having a long axis with a handgrip 3 at one end for grasping with the player's fingers and a head part 4 at the other end.

Head part 4 is typically generally ovate and planar in shape, and includes a crown 5 at the top, a throat or yoke part 6 at the bottom, a pair of oppositely-directed

faces 7 used for striking the ball or other game object, and an outer radial periphery 8 extending about head 4 on either side from crown 5 to throat 6.

In some games, e.g., tennis, squash and badminton, head part 4 comprises a generally ovate planar frame member 4 which defines an opening across which a plurality of resilient strings 9 are tightly stretched in an open weave in directions generally parallel and perpendicular to the long axis of the racket. In other games, e.g., paddle tennis, head part 4 comprises a solid paddle, which may be laminated from a plurality of generally ovate, planar wooden sections bonded together to define a solid member upon which a pair of thin, rubber or composition faces 7 are bonded.

In Fig. 1, the player is illustrated as being right-handed and engaged in a forehand swing, i.e., one in which the player's body is positioned facing to the right at generally a right angle to the desired trajectory of the ball, and in which racket 1 is brought forward from the player's right side in a controlled manner so as to impart the desired trajectory and velocity to the ball at the moment of its impact with the racket's face 7. In a backhand swing, the player's position is generally reversed, with the swing being initiated from a position of racket l to the player's left side and generally across the body of the player and toward the ball. In a serve position, particularly in the game of tennis, the player's body is directed generally facing along the intended trajectory of the ball, and racket 1 is swung generally in an overhead fashion from an initial position generally directly behind the player and in a downward arc toward the surface of the court. Some players may use both hands during a forehand or backhand return.

Teachers and skilled practitioners will readily acknowledge that, regardless of the racket sport

involved or the type of swing being employed, a problem common to beginners and neophytes is that of the "lazy racket", i.e., an inability to swing the racket with sufficient control to impart the desired velocity and trajectory to the ball at the moment of impact. There are many sources of this lack of control, including the player's initial positioning of himself relative to the ball, late or early initiation of the swing, improper racket position during swing, undeveloped muscularity, particularly in the wrist and forearm, and a lack of follow-through of the racket after its impact with the ball.

An exemplary first preferred embodiment of a training device 10 for addressing and overcoming some of these problems is illustrated generally in Fig 2. Device 10 comprises a pair of weights 12 of about equal mass which are disposed at a first position symmetrically on opposite sides of, co-planar with, and generally central of, the racket's head 4. Weights 12 are confined by means 14 to move, during a swing of racket 1, smoothly and symmetrically from the first position and along a path generally parallel, contiguous, co-extensive and co-planar with the upper portion of the outer radial periphery 8 of racket 4 and toward a second position at the racket's crown 5.

In the first exemplary preferred embodiment illustrated in Fig. 2 , the means 14 for confining the movement of weights 12 along the path co prise a cylindrical conduit 14 conformed to fit the upper portion of the outer radial periphery 8 of head 4, within which weights 12 are conformed to fit and slide smoothly during the swing.

Means 16 are provided for returning weights 12 about equally to the first position after racket l is swung and preparatory to initiating the next swing, and, in the exemplary first embodiment illustrated in Fig. 2,

comprise a pair of coil extension springs 16 each having one end attached to one of weights 12 and a second end attached to stopper means 18 located at either end of conduit 14 for confining weights 12 within conduit 14 and for stopping their downward movement at about the first position.

Operation of the trainer is simple and effective.

During the swing, head 4 of racket 1 is generally brought forward in an arc centered on the player's body.

During the initial part of the swing, inertial forces act upon weights 12 which are counteracted only by the frictional forces between weights 12 and conduit 14 and the extensive or compressive forces exerted upon weights

12 by biasing means 16. Responsively, weights 12 move from the first position, along the outer radial periphery 8, to meet, or be slightly separated, at or below the second position at crown 5 of racket 1, depending upon the accelerative forces imparted to racket 1 during the swing. Although more force is required to swing a racket equipped with the present device than that required for one not so equipped, especially during the initial portion of the swing, less force is generally required than that initially needed for a racket having training weights fixedly attached in the region of the crown. Players quickly learn the

"feel" of the swing force and control necessary to

"snap" the head of the racket smoothly during the initial part of the swing such that the weights are generally at, or close to the second position at the moment of impact, and the face of the racket is in the proper striking attitude. At the moment of impact, the head of the racket is travelling at about the same velocity as the player normally imparts to the head, but has a substantially increased inertial force acting in the direction of the swing at a point on the head in the region of the crown, which results in a higher velocity

being imparted to the ball during impact and a subsequent well-developed follow-through. In addition to enhancing velocity and follow-through, this effect also increases the top-spin imparted to the ball during the overhand swing associated with a serve, such as in tennis, as an added benefit. Finally, the additional weight associated with the device and the increased force necessary to accelerate the weights properly during an effective swing will develop the player's arm musculature more effectively than does a conventional racket, and the combined effects of using the device either during practice or play can quickly overcome the habit of "lazy racket" play.

In the first preferred embodiment illustrated, weights 12 comprise an elongated casting of lead or lead alloy. In order for weights 12 to slide smoothly within conduit 14, their radius of curvature must be conformed to be generally about that of the maximum radius of curvature of head part 4, which typically occurs toward crown 5 of head part 4. Additionally, the effective cross-sectional area of weights 12 must be conformed to be slightly less than that of conduit 14 to insure smooth sliding. In practice, it is desirable to provide device 10 with a range of replaceable weights 12 whose masses can then be adjusted over a relatively narrow range by the player or a technician in a "pro"shop, depending upon the player's individual requirements. Applicants have determined experimentally that, for tennis rackets, a desirable range of weight mass is from about 1/4 to 3 ounces, each, and is easily controlled by adjustment of the length of weights 12. Additionally, Applicants have learned that, if weights 12 are cast from pure lead, they are very soft and may become deformed within conduit 14 by large inertial forces imparted to them during a hard swing. Accordingly, it may be desirable to encase weights 12 within a stiffer

within a stiffer casing 13, e.g., either steel or tin material, or to cast weights 12 from a stiffer alloy of lead, e.g., lead and tin.

Conduit 14 may be fabricated from a variety of materials, and Applicants have good success with a clear, flexible polyethylene tubing otherwise used for conducting water. Other materials, such aluminum tubing or steel tubing may be utilized, the only requirement being that the material and the conduit 14 be ultimately conformable to the outer radial periphery 8 of the upper portion of head part 4 without substantial distortion of the conduit's cross-sectional area.

In constructing coil springs 16, it should be borne in mind that their purpose and function is solely to return weights 12 about equally to the first position between swings, and not to impede the movement of weights 12 toward crown 5 during the swing. Accordingly, and as illustrated in the exemplary first preferred embodiment, springs 16 may comprise a large number of closely-wound, steel coils heat-treated to have a relatively low spring rate, such that the springs are relatively "floppy" in the fully-contracted state.

It is desirable that the incorporation of device 10 within a training racket affect the racket's playing characteristics as little as possible. Accordingly, it is desirable that device 10 be conformed as closely as possible to the outer radial periphery 8 of the racket's head 4 and be as aerodynamically "smooth" as is compatible with its operation. Also, it is desirable to provide a form of edge protector, or cushion, for the racket in the event the player loses his grip on the racket during a swing or drops the racket on the ground. For these reasons, it is anticipated that, regardless of the means employed to confine the weights' movement to the outer radial path of head part 4, it will still be desirable to incorporate some form of the conduit 14

illustrated in the figures as an edge protector.

Additionally, it is desirable to provide the present invention either in a form which may be quickly attached and detached to an existing conventional racket, or alternatively, in a form permanently incorporated within a racket intended primarily for training. Regardless of the form chosen, it is desirable that attachment or incorporation of device 10 be achieved without substantially obscuring either of the racket's faces 7 and without substantially modifying the racket to attach device 10.

In the exemplary first embodiment illustrated in Figs. 2 and 3, device 10 is attached to frame member 4 by means of a plurality of straps 20 extending between strings 8 and about device 10 and frame member at 4 at selected positions along the length of the device, each -strap incorporating means at its ends for joining the ends and for tightening the strap thereabout. Applicants have successfully utilized a commercially- available strapping system which includes a nylon strap having a loop at one end through which the other end is irreversibly threaded and drawn down tightly by means of a pliers-like device, called a "Tie-Wrap". Means are provided within the loop and on the strap to prevent the strap from loosening after tightening. However, other strapping means may be utilized, the only requirement being that the strapping be sufficiently strong and reliable to withstand rigorous use.

When straps 20 are employed for attaching device 10 to a racket having a solid head 4, it will be necessary to modify head 4 slightly to include a plurality of elongated apertures spaced inwardly and about outer radial periphery 8 through which straps 20 may be inserted.

Two variations on the implementation of device 10 are illustrated in the exemplary second and third

preferred embodiments shown in Figs. 4 and 5, with similar or identical features being numbered identically, plus the number 100 or 200, respectively.

In the second exemplary preferred embodiment of Fig. 4, the substantial difference in implementation concerns the means for biasing weights 112 toward the first position, and in the embodiment illustrated, comprise a pair of elastomeric bands 116, each of which has one end attached to a weight 112, and the other end attached to device 110 or frame member 104 at a point at, or below, the first position. As in the case of extension springs 16 in the first embodiment, it is preferable that elastomeric bands 116 be only slightly extended when weights 112 are at the first position against stopping means 118. Accordingly, it has been found that, for elastomeric bands consisting of a resilient rubber or comprising resilient rubber compound strands, it is desirable to provide stopping means 118 with an aperture through which elastomeric bands 116 may pass to attach to head 104 at a position below the ends of conduit 114. This attachment permits adjustment of the attachment position of elastomeric bands 116 such that, at their fully contracted position, weights 112 are just maintained against stopping means 118.

The exemplary third preferred embodiment illustrated in Figs. 5 and 6 depart from the first and second preferred embodiments chiefly in the configuration of the means utilized for confining movement of weights 212 to the desired path, as well as the means utilized for biasing weights 212 generally equally toward the first position. In the exemplary third preferred embodiment, weights 212 are confined for movement by means of a rail or track 215 attached to the outer radial periphery 208 of head 204. Weights 212 each contain an aperture or feature extending in an axial direction which retain them upon the wire or rail

215, yet permit them to slide with free movement thereon, in a manner of a bead on an abacus.

Additionally, in the third exemplary preferred embodiment illustrated, the biasing means comprise a compression spring 216 having a central portion attached to device 110 at about the position of crown 205, and a pair of ends, each end being in pushing contact with one of weights 212. Spring 216 is confined between the top of track 215 and the inner diameter of conduit 214 for generally compressive and extensive movement along the desired path during and after the swing.

Alternative means for quickly attaching and detaching device 10 to racket 1 are illustrated in the cross-sectional view of Fig. 7. Therein, clamping means in the form of a split clamp 20 are provided with conventional fastener means 21 to permit simultaneous -clamping of conduit 14 to a conventional frame member 4 in a quick and reliable manner.

By now skilled practitioners will recognize that alternative methods of construction and implementation of the device are possible other than those materials and methods discussed and illustrated herein, depending upon the particular application at hand. Accordingly, the scope and spirit of our invention is limited only by the claims appended hereto.