Abstract:
A tennis ball delivery device for use in practicing one&#39;s tennis stroke. The device includes an adjustable frame, at least one declining ball delivery conduit carried by the frame in an upper portion thereof, a declining ball discharge shoot carried by and communicating with the delivery conduit and a ball release mechanism carried by the discharge conduit. The release mechanism allows a single ball to fall from the shoot in response to the activation thereof. A depending handle that can be easily struck by the player&#39;s racket in initiating their tennis stroke is operatively connected to the release mechanism so as to effect the release of the ball.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/657,952, filed Mar. 2, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a tennis ball delivery device and, more particularly, to a low cost, readily producible and easily portable device for holding a supply of tennis balls that, upon actuation by a player, will deliver a ball to the player for practicing his or her tennis stroke. While a wide variety of practice devices are presently available to tennis players for developing their strokes, they typically comprise devices that drive or shoot a ball over the net toward the player who then returns the ball using a backhand or forehand stroke. The proper tennis strokes and footwork are developed through repetitive practice. Such practice devices are relatively large and heavy and hence not easily portable which limits their use. They also require electricity and are relatively expensive, particularly for children in poor families and for people in general in less affluent countries who wish to learn the game of tennis. Because of the size and weight of such devices, they also are not easily used for practice by children and older players without assistance. Without a ball delivery device, a player or prospective player can only practice his or her strokes with a coach, which is very expensive, by hitting a ball against a wall, which generally does not provide repetitive practice of the same stroke, particularly for a novice, or by repetitively dropping a ball on the same spot and at the same height. By having to drop the ball and then turn and strike the ball, the player cannot focus on the proper body position prior to and during the stroke. Also, learning through repetition is impaired because the player has to continually leave his or her position to retrieve another ball. As a result, the rhythm of repetitive practice is lost.  
         [0003]     It therefore would be desirable to provide a device that enabled one to practice his or her tennis stroke without the aid of another person, that obviated the need to repetitively retrieve balls, that was of simple construction so as to be economical to manufacture, and that was light in weight and easily portable. Such a device should also be capable of delivering the ball to the player at predetermined variable heights to accommodate differently sized players and to enable the players to practice different strokes. Such a device would not only be beneficial to all players but be affordable by a large group of potential tennis players who can not afford the ball delivery devices currently in use. Such a device also could be used by persons unable to physically transport and set up the tennis delivery ball devices currently available. The present invention provides such a device.  
       SUMMARY OF THE INVENTION  
       [0004]     Briefly, the present invention comprises a tennis ball delivery device for use in practicing one&#39;s tennis stroke that obviates the need to retrieve a new ball after each stroke, is very economical to manufacture and is readily portable. The device carries a supply of tennis balls and, upon activation, drops a single ball from a selected and variable elevation so that the ball will bounce to a desired height where it can be struck by the player using either a forehand or a backhand stroke. In its preferred embodiment, the device comprises an adjustable and collapsible frame assembly, a pair of ball supply conduits carried in an upper portion of the assembly and a ball release mechanism carried by each of the lower outlet ends of the conduits, which project outwardly in opposed directions from the frame. The release mechanisms preferably employs a depending handle that can be easily struck by the player with his or her racket so as to effect the release of a single ball from the elevated conduit such that the ball can fall to the ground, bounce upwardly and be struck by the player. The release mechanism includes a stop for preventing more than one ball from falling from the conduit with each movement of the handle. By providing a pair of opposed ball outlets, a person can practice his or her forehand and backhand stroke without having to move the ball delivery device. The frame assembly preferably is formed in detachable sections that allows for varying the elevation of the ball conduit and nesting of the frame sections for portability and storage. One portion of the frame assembly is preferably provided with a wire grid surface that functions as a support surface during use as a ball delivery device, as a bottom flooring for the device in the nested carrying position, and as a ball retrieval device.  
         [0005]     It is therefore the principal object of the present invention to provide a ball delivery device for practicing one&#39;s tennis stroke which is highly versatile, of simple construction so as to be economical to manufacture and is readily portable.  
         [0006]     These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a perspective view of the ball delivery device of the present invention.  
         [0008]      FIG. 2  is a perspective exploded view of the ball delivery device of the present invention.  
         [0009]      FIG. 3  is a perspective view of the lower portion of the frame assembly illustrating its use as both a ball carrying device and a ball retrieval device.  
         [0010]      FIG. 4  is a sectional view taken along the line  4 - 4  of  FIG. 3 .  
         [0011]      FIG. 5  is a schematic illustration of the lower wire grid surface of the lower portion of the frame assembly functioning as a ball retrieval device.  
         [0012]      FIG. 6  is an exploded perspective view showing one of the ball delivery conduits employed in the present invention as viewed from the opposite side as  FIG. 1  and an enlarged ball collection funnel formed of welded wire that is adapted to be secured to the upper upstream end of the delivery conduit.  
         [0013]      FIG. 7  is a sectional view taken along the line  7 - 7  of  FIG. 6 .  
         [0014]      FIG. 8  is a perspective view of a ball delivery chute and attached ball release mechanism mounted on the downstream end portion of a ball delivery conduit.  
         [0015]      FIG. 9  is a side view of a ball delivery chute secured to the downstream end of a ball delivery conduit with the sidewalls broken away to illustrate the interior of the chute and conduit.  
         [0016]      FIG. 10  is an end view of a ball delivery chute and attached ball release mechanism.  
         [0017]      FIG. 11  is a partial perspective view of a portion of the intermediary frame section of the present invention showing an attached upper frame support bracket in the folded position.  
         [0018]      FIG. 12  is a partial perspective view of a portion of the intermediary frame section of the present invention showing an attached upper frame support bracket in the extended support position.  
         [0019]      FIG. 13  is a partial sectional view of portions of the intermediary frame section of the present invention showing an upper frame support bracket in the folded position and an intermediary support bracket in the extended support position with a position of the upper frame section resting thereon.  
         [0020]      FIG. 14  is a perspective view of the ball delivery device of the present invention in the nested transportation and storage mode.  
         [0021]      FIG. 15  is a perspective view of an alternate embodiment of the present invention.  
         [0022]      FIG. 16  is a perspective view of a second alternate embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     The tennis ball delivery device  10  of the present invention includes a frame  12  that is preferably adjustable and collapsible, one or more ball delivery conduits  14  carried within an upper portion of the frame, a ball delivery chute  16  affixed to the lower end of each of the conduits and a ball release mechanism  18  carried by the downstream end of each of the ball delivery chutes. In a preferred embodiment of the invention illustrated in  FIGS. 1-14 , the frame  12  comprises an upper frame section  12 A, an intermediary frame section  12 B and a lower frame section  12 C. The ball delivery conduit  14  is carried within the upper frame section  12 A and comprises a pair of separate conduits  14 A and  14 B nested together in a helical array. A pair of corresponding ball delivery chutes  16 A and  16 B are affixed to the lower ends of ball conduits  14 A and  14 B and a pair of ball release mechanisms  18 A and  18 B are carried by the downstream ends of the ball delivery chutes.  
         [0024]     The upper frame section  12 A is preferably formed of a welded wire construction so as to render the frame section relatively rigid, substantially transparent and light in weight. It is to be understood that other durable and lightweight frame constructions could be employed and that the particular wire structure illustrated in the drawings is merely a representative example of one of a variety of welded wire configurations that could be employed to form the upper section  12 A of the delivery device  10 .  
         [0025]     As seen in  FIGS. 1 and 2 , the frame upper section  12 A defines an open upper end  20  circumscribed by a horizontally disposed circular upper wire  22  and bordered by a plurality of vertical frame wires  24 . The lower end of the upper frame section  12 A is provided with a horizontally disposed lower wire ring  26  to which the lower ends of the vertical wires  24  are welded or otherwise suitably secured. A wire grid  28  is provided interiorly of the lower ring  26  to define a flooring for the upper frame section that supports the ball delivery conduits  14 A and  14 B disposed therein as seen in  FIGS. 1 and 2 . The upper frame section  12 A also may include one or more intermediary horizontal ring wires (not shown). Again, other suitable frame configurations could be employed.  
         [0026]     The ball delivery conduits  14 A and  14 B are preferably provided with ball collection funnels  30 A and  30 B at their upper inlet ends and extend downwardly therefrom in opposed nested helical paths about the interior of the upper frame section  12 A to their respective outlet ends  32 A and  32 B. As with the upper frame section  12 A, the ball delivery conduits  14 A and  14 B (which are schematically illustrated in the drawings) are preferably formed of a wire configuration so as to be light in weight and to allow the user to be able to see and reach through the sidewalls of the conduits to identify any ball jams therein and relieve those jams by simply inserting a finger through the conduit wall and loosening the jammed balls. The delivery conduits and collection funnels, while preferably formed of wire, appear solid in the drawings as they are schematically illustrated so as not to overly clutter the interior of the upper frame section  12 A in the drawings as would occur if the ball delivery conduits were illustrated in more detail in their preferred wire construction. A ball collection funnel  30 B formed of welded wire is illustrated, however, in  FIG. 6 .  
         [0027]     It is important that the ball delivery conduits  14 A and  14 B be formed so that a tennis ball can roll downwardly therethrough without obstruction.  FIG. 7  illustrates a cross section of a representative example of such a conduit construction. As seen therein, the conduit  14 B is formed of a plurality of annular wires  15  and longitudinal wires  17  that are disposed interiorly of the annular wires so that the balls can roll along the longitudinal wire  17  unimpeded by the annular wires  15 . As with the construction of the frame section, other wire and non-wire conduit configurations could be employed. For example, the annular wire portion of the two helical conduits could be formed of a single or plurality of helically extending wires (similar to a coil spring) as opposed to a plurality of individual axially spaced annular wires. Alternatively, the conduits could be formed of a solid material such as plastic. Such a solid construction, however, may employ a transparent or translucent material so that interior ball jams can be readily identified and apertures should be provided in the sidewalls of such conduits so that the user can readily clear any such ball jams.  
         [0028]     The opposed ball delivery chutes  16 A and  16 B attached to the lower downstream ends of conduits  14 A and  14 B (see  FIG. 8 ) extend exteriorly from the frame in a downward inclination and are preferably constructed of a transparent or translucent durable plastic material and provided with flared upstream end portions  16 ′ so as to fit about the downstream ends of the ball delivery conduits in a press fitment. Such an attachment allows the chutes to be readily removed for transporting and storage.  
         [0029]     Ball release mechanisms  18 A and  18 B are provided on the delivery chutes. The preferred release mechanism is manually activated to reduce costs and, as seen in  FIGS. 8-10 , comprises a depending elongated handle  38  that is rigidly affixed to a rod  40 . Rod  40  is axially aligned with and rotatably mounted on the underside of the chutes by brackets  42 A and  42 B. A first downstream stop member  44  is affixed to and extends from rod  40  in opposed substantial axial alignment with handle  38  and projects into the interior of the adjacent chute through a slot  46  formed in the underside of the chute. Stop member  44  can be of any desired configuration as its function is simply to block the lower end of the discharge chute when the handle  38  is hanging in a vertical disposition. A generally circular disc or paddle-shaped configuration is illustrated in the drawings (see, e.g.,  FIG. 8 ). A second stop member  48  is also provided on each of the rods  40  and projects radially therefrom at a 90° angle with respect to the first stop member  44 . A second slot  50  is provided in the lower and side portions of the discharge chutes upstream of slot  46  so that the second stop member  40  can project therethrough into the chute. The spacing between slots  46  and  50  and thus between stop members  44  and  48  is about 2.5 inches which is substantially equal to the diameter of a tennis ball (a new ball is typically within the range of about 65-66 mm.).  
         [0030]     As a result of the aforesaid configuration, the elongated handles  38  on the ball release mechanisms will hang under the force of gravity in vertical dispositions from the rotatably mounted rods  40  as shown in  FIG. 8 . In this position, the first stop members  44  project upwardly from rods  40  into their respective discharge chutes, blocking the outlet ends of the chutes and thus preventing any tennis balls disposed within the chutes from falling from the chutes. In this orientation, the second stop members  48  projects outwardly from rods  40  in directions normal to the first stop members  44 , exteriorly of the discharge chutes as seen in  FIGS. 8 and 10 . Rotation of one of the release handles  38  causes corresponding rotation of rod  40  and of the two stop members affixed thereto. The first stop member  44  rotates out of the path of any balls within the discharge chute, while concurrently bringing the second stop member  48  into the path of the balls in the chute directly behind the lead ball. Accordingly, if the chute were filled with tennis balls as seen in  FIG. 8 , and the user were to strike the release handle  38  with his or her tennis racket so as to rotate the handle, the bar  40  will also rotate, causing the first stop member  44  affixed thereto to move out of the path of the lower most ball, whereupon the ball will fall from the discharge chute as illustrated in  FIG. 1 . Concurrently, the second stop member  48  is rotated into the path of the next ball in line, preventing that ball and any balls behind it from advancing within the discharge chute. When the handle returns to its depending vertical position, the first stop member returns to its ball blocking or stop position illustrated in  FIGS. 8-10  and the second stop rotates back out of the path of the then lowermost ball in the chute, allowing that ball to advance to a position adjacent the first stop member. Any balls behind it in the chute will also advance. To facilitate the return rotation of handle  38  after the lead ball falls from the discharge chute, a spring member  51  can be operatively connected between the rotating rod  40  and the chute. Spring member  51  could be a coil spring, torsion spring or any other suitable biasing means that would return the first stop member  44  to the ball blocking position. Thus, each time a person hits the release handle  38  with his or her racket so as to cause the handle to pivot from about 45°-90°, depending on the configuration of the first stop member  44 , one ball will fall from the chute to be hit by the player and each ball in the ball delivery conduit communicating with that chute will advance one spot, i.e., a distance equal to the diameter of one ball.  
         [0031]     In use, a person will hit the ball using either a backhand or forehand stroke after the ball falls from the discharge chutes  16 A or  16 B and bounces to a predetermined height. By providing two opposed discharge chutes, one can hit both forehand and backhand shots without having to rotate the frame 180°. The height to which the ball will bounce depends on the elevation of the discharge chute above the ground. Accordingly, to accommodate players of varying height and to enable a player to practice hitting the ball at various elevations, the frame  12  should be adjustable in elevation. This is accomplished in the embodiment of the invention illustrated in  FIGS. 1-14  by means of the intermediary frame section  12 B.  
         [0032]     As seen in  FIGS. 1 and 2 , the upper frame section  12 A, which carries the ball delivery conduits  14 A and  14 B and thus discharge chutes  16 A and  16 B, is mounted on or partially within the intermediary frame section  12 B which in turn sits atop of the lower frame section  12 C. For reasons to be explained, the lower frame section  12 C is preferably constructed of an inexpensive lightweight plastic material so as to define a solid cylindrical wall  52  for the lower frame section. The lower end  54  of the lower frame section is open and a wire mesh grid  56  extends thereacross. For reasons to be explained, the spacing between the laterally extending wires  56 ′ in grid  56  are spaced apart about 2.25 inches, a distance slightly less than the diameter of a worn tennis ball. During normal use, the grid  56  simply forms the upper surface of the lower frame section and provides a support for the intermediary frame surface  12 B.  
         [0033]     Intermediary frame section  12 B, like the upper frame section  12 A, is preferably of a welded wire construction and comprises an upper, circular, horizontal ring wire  58 , a lower, circular, horizontal ring wire  60  and a plurality of vertically extending support wires  62  which are welded or otherwise secured to the upper and lower ring wires  58  and  60 . Depending on the gage of the wire employed in the formation of the intermediary frame section  12 B and the rigidity of the section desired, one or more ring wires (not shown) could also be secured to the vertical support wires  62  intermediary of the upper and lower wires  58  and  60 . As seen in  FIG. 1 , the frame sections  12 A,  12 B, and  12 C define diameters such that the lower ring wire  62  of the intermediary frame section  12 B and the attached vertical support wires  62  fit on the support grid  56  of the lower frame section  12 C inwardly adjacent an upper perimeter wall  64  defined by the upper end of the cylindrical sidewall  52  of the lower frame section  12 C. A plurality of upstanding tabs  66  are preferably welded or otherwise affixed to the grid  56  in a circular array so as to bear against the lower horizontal ring wire  60  of the intermediary frame section  12 B, securing the lower end of the intermediary frame section  12 B on the lower frame section  12 C as illustrated in  FIG. 1 .  
         [0034]     The upper frame section  12 A in turn fits at least partially within the intermediary frame section  12 B as is also illustrated in  FIG. 1  and is supported therein at a desired height by a plurality of support brackets  70 . In the drawings, three support brackets  70  are shown as being provided on three equiangularly-spaced vertical support wires  62  of the intermediary frame section to provide a balanced support surface for the upper frame section. If desired, a greater or perhaps a lesser number of the vertical support wires could be provided with the support brackets  70 , depending on the frame design. By providing three vertically spaced brackets  70  on the individual vertical support wires  62 , the elevation of the support surface provided by the brackets can be varied. Similarly, a greater or lesser member of support brackets could be employed on the vertical support wires depending on the frame design and the desired member of height adjustments.  
         [0035]     The individual support brackets  70  are illustrated in  FIGS. 11-13 . As seen therein, each bracket includes a cylindrical body portion  72  that is rigidly affixed to a vertical wire  62  and a “U”-shaped support member  74  which is bifurcated over approximately two-thirds of its length to define a stop  76  and is pivotally mounted on the body position  72  by a pin  78 . When the support brackets  70  are in the collapsed or folded position, illustrated in  FIG. 11 , the “U”-shaped support portion  74  of the bracket is substantially flush with the cylindrical body portion  72  so as not to interfere with the sliding movement of the upper frame section through the intermediary frame section during assembly. When the “U”-shaped support portion  74  is pivoted about the mounting pin  78 , as seen in  FIG. 12 , the stop  76  defined by the termination of the bifurcated portion of the bracket abuts the cylindrical body portion  72  so as to hold the “U”-shaped support portion  74  in a horizontal disposition. So disposed, the right side of the support portion  74  of the bracket  70  (as seen in  FIG. 12 ) will support a vertical force such as the weight of the upper frame section  12 A, ball delivery conduits  14 A and  14 B and the associated chutes  16 A and  16 B and ball release mechanisms  18 A and  18 B. It is to be understood, that other bracket configurations and indeed other means of adjusting the elevation of the ball discharge chutes  16 A and  16 B could be employed in the present invention. For example, the vertical support legs  62  of frame section  12 B could be of a telescoping configuration.  
         [0036]      FIG. 13  illustrates the intermediary of the three vertically spaced support brackets  70  on one of the vertical support wires  62  on the intermediary frame section in the extended position, supporting the upper frame section  12 C, and the upper bracket  70  on the same vertical support wire  62  in the folded position so as not to interfere with the insertion of the upper frame portion onto the intermediary support bracket  70 . In such a disposition, all of the intermediary support brackets  70  would be disposed in the support position to effectively define a planar support for the upper frame section. In this position, an intermediate elevation of the ball delivery chutes  16 A and  16 B is provided. If the player wished to practice his hitting the ball at a higher elevation, the upper frame portion  12 A would be mounted on the uppermost support brackets  70 . Conversely, mounting the upper frame section  12 A on the lower support brackets would provide a lower bounce and positioning the lower end of the upper frame portion directly on the support grid  56  would provide an even lower ball bounce for the player.  
         [0037]     In addition to providing a variety of elevations at which the discharge chutes can be readily and securely positioned, the aforesaid frame configuration allows the individual frame sections to be nested together for carrying and storage as illustrated in  FIG. 14  and for the lower frame section  12 C to be individually used to collect tennis balls as illustrated in  FIGS. 3-5 . As previously described, the lateral wires  56 ′ defining grid  56  on the lower frame section are spaced apart about 2.25 inches, i.e., slightly less than the approximate diameter of a worn tennis ball. Thus, by removing the upper and intermediary frame sections from the lower frame section  12 C and inverting the lower frame section, the grid  56  now becomes a bottom surface for the section as illustrated in  FIG. 13 . Pressing the bottom grid surface of the frame section over a tennis ball will cause temporary deformation of the ball so that the ball can pass between the wires  56 ′ of grid  56  and into the interior of the lower frame section as seen in  FIG. 5 . The balls quickly return to their unstressed state and will thus be held within the inverted lower frame section. A pivotally mounted handle  80  preferably is provided on the lower frame section at the opposite end thereof from grid  56  so as to effectively convert the lower frame section  12 C into a ball collection bucket as illustrated in  FIG. 3 .  
         [0038]     As noted previously, the individual frame sections when detached can be nested together for transportation and storage, such a configuration is illustrated in  FIG. 14 . As seen therein, the helically nested delivery conduits  14 A and  14 B remain positioned within the upper frame section  14 A with the ball delivery chutes  16 A and  16 B removed. Those chutes are simply positioned interiorly of the coiled delivery conduits  14 A and  14 B and are supported by the grid  28  at the lower end of the upper frame section. With all of the support brackets  70  in the folded position, the upper frame section will slidably fit within the intermediary frame section. A pivotally mounted closure  79  is preferably provided adjacent the outlet ends  32 A and  32 B of the ball delivery conduits to enable the conduits to carry a supply of tennis balls when the device  10  is in the transportation and storage mode illustrated in  FIG. 14 . In its inverted position, the lower frame section  12 C can accommodate the nested upper and intermediary frame sections and the elements carried thereby within the cylindrical wall  52  of the lower frame section. In this regard, it should be noted that the cylindrical wall  52  could be made of a variety of lightweight inexpensive materials including plastic metal sheeting and welded wire.  
         [0039]     As is also illustrated in  FIG. 14 , handle  80  which is employed when using the lower frame section by itself as a ball retrieval device is also utilized for carrying the entire ball delivery device in the nested transportation and storage mode. Handle  80  preferably is pivotally mounted at one end  82  to the lower frame section  12 C so that it can be positioned to the side of the device  10  during use as seen in  FIG. 1 . The other end of handle  80  is preferably defines an attachment hook  84  or other suitable connector that is adapted to extend through a slot or engage a projection provided on the opposite open end of the lower frame section such that the handle  80  can also function as a carrying handle as above described.  
         [0040]     A second embodiment of the present invention is illustrated in  FIG. 15 . In the tennis ball delivery device  100  illustrated therein, the frame  112  comprises a plurality of telescoping legs (three being shown)  112 A,  112 B, and  112 C joined at their upper ends in a circular support ring  112 D. The upper ends of the legs can be permanently secured to the upper support ring by welding or an adhesive suitable for the materials of which the frame is constructed or removeably secured by a threaded engagement or other suitable fastening means. The frame could be constructed of a durable plastic or a metal material. The ability of the legs to telescope allows for variation in the elevation of the ball delivery chute  116 . The telescoping function can be provided by conventional threaded clamps  117  that compress a slotted end of an outer leg section about a portion of an inner leg section as illustrated in the drawing. Other telescoping leg configurations could, of course, be employed. For example, a plurality of a longitudinally spaced apertures could be provided on the lower leg portions and a spring biased pin provided on each of the upper leg portions which slide within the lower leg portions and are secured thereto at the desired elevation by the pins projecting through the selected apertures. Other telescoping means could also be employed.  
         [0041]     The ball collecting conduit in the delivery device  100  comprises a large funnel  114  which fits within and is supported by the support ring  112 D on the frame. The ball delivery chute  116  is preferably removable from the bottom of the funnel  114  for storage and travel and comprises an upper vertical portion  116 A and lower inclined portion  116 B so as to define a continuous downward path for the sequential delivery of tennis balls from the funnel through the chute. A ball release mechanism  118  similar to that employed in the prior embodiment is carried by the delivery chute as illustrated in the drawing. To prevent the lower outlet end of the funnel from being clogged with balls, a conventional vibrator  119  can be attached thereto so that in the event the funnel fails to properly feed balls, the vibrator could be activated by a push button  121  or a remote control activation device to effect the vibration of the funnel and an unclogging of the ball jam at the bottom of the funnel.  
         [0042]     In use, the ball delivery device of  FIG. 15  is operated in the same manner as the device  10  of the prior embodiment. However, if only a single outlet chute is employed as shown, it will be necessary to reverse the orientation of the device  100  to practice both backhand and forehand strokes.  
         [0043]     A third embodiment of the invention is illustrated in  FIG. 16 . The ball delivery device  200  of  FIG. 16  differs from that of  FIG. 15  primarily in the design of the frame  212  and the means for activating the ball drop mechanism. As indicated earlier, a wide variety of frame constructions could be employed in the present invention. Frame  212  comprises a single leg comprised of an upper portion  212 A and lower portion  212 B and a bottom pedestal stand support  213 . As with the prior embodiment, a variety of means could be employed to effect the telescoping of the frame  212 . A conventional threaded attachment  217  is illustrated in  FIG. 16 . The remainder of the components of the delivery device  200  are basically identical to those in the above-described device  100  except that the ball delivery device  200  is provided with an automatic delivery chute activator  225 . The activator  225  eliminates the need for a player to physically strike the ball release handle as in the prior embodiments. Activator  225  can be a conventional timer such as those employed in ball pitching machines and could allow the user to set the frequency of the ball drop, i.e., interval of the rotation of the rod carrying the first and second stop members  244  and  248  respectively. Such a timer would allow the user to rhythmically practice his or her strokes by providing a constant time duration between the dropping of each ball. Alternatively, the activation device  225  could comprise a motion detector activated by the user swinging his or her racket in front of the emitting end  225 ′ of the device. Such a detector could be of any suitable type such as a photo sensor, a capacitance activated detector or a remote control activation device. The ball delivery device  200  also may employ a vibrator  219  to assist in maintaining a continuous passage of tennis balls through the funnel  214  and attached discharge chute  216 .  
         [0044]     Various other changes and modifications may be made in carrying out the present invention without departing from the spirit and scope thereof.