Patent Publication Number: US-6213900-B1

Title: Concave rebounding surface for playing a ball game

Description:
FIELD OF THE INVENTION 
     The present invention relates to equipment for a ball game. 
     DESCRIPTION OF RELATED PRIOR ART 
     Squash is a ball game normally confined to the indoors. The nature of the game requires a hard floor (e.g., parquet), and at least three surrounding walls, each at right angles to the ground and to the adjacent wall. The game proceeds as one of two players uses a racket to hit a ball against the middle or front wall of the playing room. The ball is allowed to rebound from the wall, then hit and bounce off the ground. At this point, a second player intercepts the ball, using his or her racket to hit the ball toward the middle or front wall. 
     OBJECT OF THE INVENTION 
     The object of the present invention is to provide equipment which makes it possible for a ball game similar to squash to be played outdoors. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following embodiments of the present invention are explained in more detail with reference to the enclosed drawings: 
     FIG. 1 shows in a plan view a field for a ball game comprising an arrangement off which a ball may rebound. 
     FIG. 2 shows in a front view the arrangement of FIG.  1 . 
     FIG. 3 shows in a side view the arrangement of FIG.  1 . 
     FIG. 4 shows in a back view the arrangement of FIG.  1 . 
     FIG. 5 shows in a top view the arrangement of FIG.  1 . 
     FIG. 6 shows an exploded representation of the arrangement of FIG.  1 . 
     FIG. 7 shows an enlarged detail of FIG.  2 . 
     FIG. 8 shows an exploded representation of a vertical cut through FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     Referring to FIG. 1, the present invention comprises a rebounding surface ( 1 , FIG. 1) attached to a support stand ( 2 ). The device is placed outside a playing area ( 3 ), either indoors or out. Optimally, the midpoint of the stand ( 2 ) aligns with that of one edge of the playing area ( 3 ). Players (A,B) then take turns hitting a ball (D) against the rebounding surface ( 1 ). The ball (D) follows the trajectory (C), whereby the ball (D) rebounds off surface ( 1 ) but remains within the area of the playing field ( 3 ). 
     Referring now to FIGS. 2-8, the rebounding surface ( 1 ) has a main body ( 5 ) in the shape of a segment of the interior surface of a cylinder. The axis (not shown) of the main body ( 5 ) runs diagonally to a horizontal plane. This main body has a rear surface ( 7 ) and a concave front surface ( 6 ), wherein these surfaces extend parallel to each other. The main body ( 5 ) is inclined such that its upper edge is more distant from the playing field ( 3 ) than is its lower edge. The angle of incline (α) is preferably between 55 and 85 degrees, 75 degrees being optimal. 
     The preferred angle of incline (α) of the front surface ( 6 ) causes the ball (D) to follow a trajectory in the shape of an upward convex bow. The location at which the ball hits the floor or ground of the playing field (i.e., the distance from the front of the rebound surface ( 6 )) depends oil the magnitude of the angle of incline. This creates interrelation between the magnitude of the angle of incline and the dimensions of the playing field ( 3 ), particularly as to the depth or length thereof. 
     The rebound surface&#39;s convex front ( 6 ) causes the ball (D) to rebound within the confines of the playing field ( 3 ), even if the ball (D) fails to impact the middle region (M) of the front surface ( 6 ). Hence, there is also an interrelation between the curvature of the front surface ( 6 ) and the dimensions of the playing field ( 3 ), particularly the width of the playing field. The radius (R) of the curvature of the front surface ( 6 ) can, for example, amount to a maximum of 1.45 m for a playing field spanning a width of 4 m. Under such circumstances, the rebounding surface ( 1 ) may have a width (T) of 1.25 m and side edges (H) of 1 m in length. 
     In a first embodiment of the present invention, the rebounding surface ( 1 ) has a thick walled main body ( 5 ), optionally of uniform thickness. The rear surface ( 7 ) or the main body runs substantially parallel to the front surface ( 6 ). 
     In the rim areas of the main body ( 5 ), four thick or wide edge surfaces ( 11 , 12 , 13 , 14 ) extend between the front surface ( 6 ) and the rear surface ( 7 ). The main body ( 5 ) is positioned in such a way that two of the wide edge surfaces ( 11 , 13 ) extend substantially in a vertical direction and the two remaining edges ( 12 , 14 ) extend substantially horizontally. The horizontal edge surfaces ( 12 , 14 ) are arch shaped like the main body and are oriented substantially normal to surface line M. Furthermore, the inclination of the main body ( 5 ) causes the distance between the upper arched edge surface ( 12 ) and the playing field ( 3 ) and players (A,B) to be greater than that between said field and players and the lower arched edge surface ( 14 ). Edge surfaces  11  and  13  are essentially straight. 
     The stand ( 2 ) comprises two L-shaped supports ( 21 , 22 ). Each support ( 21 , 22 ) consists of a single piece of an elongated material bent to form an angle. This elongated material, which may be of steel, aluminum, or the like, can have a rectangular or circular cross section. Each support ( 21 , 22 ) possesses corresponding legs ( 23 , 24 ) (FIG.  3 ). The magnitude of angle (β), extending between legs  23  and  24 , is the same as that of the angle of incline (α) of the main body ( 5 ). When in use, the rebounding surface ( 1 ) is engaged with the upper legs ( 23 ) of the supports ( 21 , 22 ). 
     Sets of support pairs ( 21 , 22 ) are possible, whereby the angle (β) between support legs ( 23 , 24 ) have different magnitudes, preferably (as with the magnitude of angle α) between 55 and 85 degrees. In such instances, the angle of incline of the main body ( 5 ) may be adjusted according to which set of support legs ( 23 , 24 ) said main body is attached. 
     In the present invention, the rebounding surface ( 1 ) is provided with two spaced sleeves ( 26 , 27 ) positioned near the lower edge surface ( 14 ) of the main body ( 5 ). The longitudinal axis of each sleeve ( 26 , 27 ) is essentially normal to the lower edge surface ( 14 ) of the main body ( 5 ) and is substantially parallel to surface line M of the main body ( 5 ). The bottom of the spaced sleeves ( 26 , 27 ) may rest on the lower edge surface ( 14 ) of the main body, or, alternately, sleeves  26  and  27  may be partially or completely sunk therein. Sleeves  26  and  27  may also be attached to the rear surface ( 7 ) or the main body ( 5 ). The free end portion of the upward directed support leg ( 23 ) of supports  21  and  22  fits into sleeves  26  and  27 , respectively, and, if necessary, is also secured thereto. The resulting setup is best illustrated in FIG.  3 . 
     In a further embodiment of the present invention, the main body ( 5 ) of the rebounding surface ( 1 ) may be composed of more than one individual sections or panels (e.g.,  31 , 32 , 33 ), as seen in FIG.  6 . Each panel ( 31 , 32 , 33 ) has the form of a segment of the surface of a cylinder, such that each has a front surface ( 6 ) and upper ( 12 ) and lower ( 14 ) arched edge surfaces. The uppermost panel ( 31 ) is attached to the next lower panel ( 32 ) in such a way that the lower arched edge ( 14 ) of the uppermost panel rests atop the upper arched edge surface ( 12 ) of the next lower panel ( 32 ). In this manner, the superposition of several panels atop each other forms a uniform, curved surface ( 6 ) of a rebounding surface ( 1 ). 
     By way of example, if the vertical edge surfaces ( 11 , 13 ) of the main body ( 5 ) are approximately 1 m long, and said main body is comprised of three panels ( 31 , 32 , 33 ), then the vertical edge surfaces ( 111 , 112 , 113 , 131 , 132 , 133 ) of said three panels ( 31 , 32 , 33 ) are each approximately 33.3 cm in length. 
     The use of multiple panels to build the main body ( 5 ) of the rebounding surface ( 1 ) permits the user to adjust the surface area of the device according to his or her skill level. A beginner will most likely want to use all panels ( 31 , 32 , 33 ) to maintain a larger playing surface, whereas a more experienced player can increase the difficulty of the game by removing one or more panels. 
     For optimal results, it is necessary that the front surface ( 6 ) of the rebounding device ( 1 ) be as smooth as possible. It is therefore essential that the edges ( 121 ,  141 ) of the horizontal rim surfaces ( 12 , 14 ) of neighboring panels  31 , 32 , and  33  remain in the plane of the front surface ( 6 ) throughout the lifetime of the device. To this end, means for mounting and securing the neighboring panels ( 31 , 32 , 33 ) in exact alignment are foreseen. Specifically, there are provided pins or pegs ( 36 , 37 ) and openings ( 38 , 39 ) for insertion of said pins ( 36 , 37 ) therein. As seen in FIGS. 6 and 8, these pins ( 36 , 37 ) protrude from the upper arched edge surface ( 12 ) of each panel ( 31 , 32 , 33 ). The openings ( 38 , 39 ) into which the pins ( 36 , 37 ) fit are situated on the lower arched edge surface ( 14 ) each panel ( 31 , 32 , 33 ). The form and dimensions of the pins ( 36 , 37 ) and the holes into which they fit ( 38 , 39 ) should correspond as closely as possible, so as avoid any movement, shifting, or misalignment of the panels ( 31 , 32 , 33 ) due to loose connections therebetween. In the present example, pins  36  and  37 , as well as their respective holes ( 38 , 39 ), all have rectangular cross sections. It should be understood, however, from the above description, that the cross-section of the pins and holes may have other forms, e.g., circular. 
     To minimize manufacturing costs, it is preferable that all panels ( 31 , 32 , 33 ) are of the same shape. Hence, the fitting pins ( 36 , 37 ) project upwards from the upper arched edge surface ( 12 ) of the main body panels ( 31 , 32 , 33 ), and the receiving holes ( 38 , 39 ) for said pins are positioned on the lower arched edge surface ( 14 ) of the main body panels ( 31 , 32 , 33 ). 
     The receiving holes ( 38 , 39 ) of the lowermost panel ( 33 ) cannot engage with any fitting pins ( 36 , 37 ). However, if, as is contemplated in the present invention, the cross sections of the main body&#39;s support legs ( 21 , 22 ) are identical to that of the receiving holes ( 38 , 39 ), the upper portion ( 23 ) of said support legs ( 21 , 22 ) may be inserted into the receiving holes ( 38 , 39 ) of the lowermost panel ( 33 ). In such a situation, separate means can be omitted for receiving the upper legs ( 23 ) of main body supports  21  and  22 . The fitting pins ( 36 , 37 ) of the uppermost panel ( 31 ) may be used for other purposes. 
     The main body ( 5 ) of the rebounding surface ( 1 ) must possess sufficient mass to permit the ball (D) to rebound back to the players (A,B) with adequate force. It is essential, therefore, that the main body ( 5 ) and the panels of which it is comprised ( 31 , 32 , 33 ) constitute a relatively thick material. Alternatively, the front surface ( 6 ) of the main body ( 5 ) and its panels ( 31 , 32 , 33 ) may consist of a thin plate ( 40 ) from which reinforcing ribs project to impart the necessary mass to the rebounding surface. According to the present invention, one reinforcing rib ( 41  or  42 ) attaches to one arched edge surface ( 12  or  14 ). 
     If the main body is comprised of panels ( 31 , 32 , 33 ), as in FIG. 8, then each arched edge surface ( 12 , 14 ) is reinforced with one rib ( 41 , 42 ). More specifically, the ribs ( 41 , 42 ) are oriented such that they extend essentially horizontally, the outer lateral surface of each rib ( 41 , 42 ) lying flush with its corresponding arched edge surface ( 12 , 14 ). If necessary, additional horizontal ribs may be positioned between and parallel to ribs  41  and  42 . 
     Additionally, vertical ribs may be utilized, said ribs protruding from the rear surface of the thin surface plate ( 40 ). These ribs may be positioned along the vertical edge surfaces ( 11 , 13  or  111 , 112 , 113  and  131 , 132 , 133 ) or in the middle region of the thin surface plate ( 40 ). 
     The main body ( 5 ) or the panels ( 31 , 32 , 33 ) of which it may be comprised are preferably made of plastic, for example, polypropylene. 
     If the main body ( 5 ) of the rebounding surface ( 1 ) is comprised of superimposed panels ( 31 , 32 , 33 ), it is preferable to use means in addition to the fitting pins ( 26 , 27 ) to hold said panels ( 31 , 32 , 33 ) together. In the present invention, the use of U-shaped clamps ( 45 ) is contemplated. Each clamp ( 45 ) has parallel legs ( 46 , 47 ), the end portion of one leg connected by a bridge ( 48 ) with the end portion of the other leg. Furthermore, the distance between the inside surfaces ( 461 , 471 ) of the clamp legs is such that the horizontal edge ribs ( 41 , 42 ) may be positioned between the inside surfaces ( 461 , 471 ) of the clamp ( 45 ). 
     Although the foregoing disclosure relates to a rebound surface for squash players, because the inclination of the rebounding surface ( 6 ) returns the ball (D) to the players along an arcuate path, the device ( 1 ) is appropriate for use on soft ground, such as a beach or lawn. The concave surface of the main body ( 5 ) prevents the ball (D) from leaving the playing field ( 3 ), even when the ball (D) is not hit into the middle region of the main body ( 5 ).