Patent Publication Number: US-7214137-B2

Title: Portable golf swing practice device having a separable cord shield incorporated therein

Description:
This application claims the benefit of U.S. Provisional Application No. 60/672,551, filed on Apr. 19, 2005. 

   FIELD OF THE INVENTION 
   This invention pertains to portable golf swing practice devices, and more particularly it pertains to a shield enclosing the tether cord of a golf swing practice device for preventing damaging the cord when the ball is struck low. 
   BACKGROUND OF THE INVENTION 
   Portable golf swing practice devices are generally used indoors during winter to exercise a golfer&#39;s skills in swinging a golf club with precision. These devices have been in use for many years, and perhaps the most common ones are characterised by their structures, each having a floor pad on which is mounted a golf ball. The ball is held to the floor pad by an elastic cord, or by other tee structure mounted on a slider that is connected to a spring. When the ball is struck, the elastic cord or the spring extends and causes a pointer to record the ball&#39;s travel distance. The extension of the spring or of the cord is then converted in yards of theoretical distance the ball could have travelled on a normal golf course. Examples of these golf swing practice devices are described in the following documents;
     U.S. Pat. No. 3,830,504 issued to B. B. Koo on Aug. 20, 1974;   U.S. Pat. No. 4,084,822 issued to J. H. Keeton on Apr. 18, 1978;   U.S. Pat. No. 4,609,197 issued to G. M. Vodin on Sep. 2, 1986;   U.S. Pat. No. 5,417,427 issued to M. S. Doane on May 23, 1995.   

   In another type of similar portable golf practice devices, the elastic cord extends and causes the ball to hit one of several targets on the floor pad so as to leave a mark on the target or to trigger a signal from one or more switches incorporated in the floor pad. The mark on the target or the triggered signal is representative of the theoretical ball direction, velocity or range. Examples of golf practice devices of this other type are described in the following documents:
     U.S. Pat. No. 2,656,720 issued to F. W. Sonnett on Oct. 27, 1953;   U.S. Pat. No. 5,386,997 issued to G. C. Smith on Feb. 7, 1995.   

   Although several portable golf swing practice devices can be found in the prior art, those that are of a particular interest herein are those where the balls are held to the floor pads by means of elastic tether cords. It has been found that these tether cords are particularly vulnerable to shear stresses and cuts. The occurrence of these stresses is particularly noticeable when the ball is struck low. The cords on these devices must be replaced often, or else, the risk of a cord breakage remains high. Therefore, it is believed that there is a market need for a golf swing practice device that has an effective cord shield thereon to minimize transverse shocks on the cord and so that the device can be used safely indoors. 
   SUMMARY OF THE INVENTION 
   In the present invention, however, there is provided a golf swing practice device that has an elastic cord enclosed in a separable cord shield. The cord shield is mounted below the golf ball such that it can absorb the impact of a low strike. 
   More specifically, according to one aspect of the present invention, the golf swing practice device has a floor pad; a hollow tee extending upward from a surface of the floor pad, and a ball resting on an end of the tee. An elastic cord is attached to the ball and to the floor pad and extends through the tee. The golf swing practice device also has a socket on a lower end of the tee and a bulge on a surface of the pad. The bulge has a forward-facing slot therein enclosing the strike side of the elastic cord. The socket on the tee encloses the bulge. 
   When a ball is struck low, the impact of the club head on the tee causes the socket to slide upward over the bulge or tilt forward about the bulge for absorbing the impact of the club head. A major portion of the impact is redirected upward, whereby direct shear stresses on the elastic cord are substantially reduced. 
   In another aspect of the present invention, the socket on the tee and the bulge on the floor pad have complementary spherical shapes that are easily but fitly mounted over and into one another. The tee is easily detachable from the bulge to follow the ball during a strike. Because of the detachable aspect of the socket-and-bulge arrangement, the swing of the club is substantially unaffected by the presence of the hollow tee. 
   In another aspect of the present invention, the golf swing practice device also has a ramp on the floor pad on a strike side of the bulge. This ramp is advantageous for deflecting very low shots that may cut the surface of the socket, or otherwise hit the surface of the socket at a right angle. 
   In yet another aspect of the present invention, the golf swing practice device has a semi-circular groove in a surface of the floor pad. This semi-circular groove is centred on the bulge, on a forward side of the bulge. The groove is positioned relative to the bulge, to interfere with the return motion of the tee, for catching the rim of the socket on the tee, and for tilting the tee to a vertical alignment over the bulge. 
   This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the present invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 
       FIG. 1  is a perspective rear and left side view of the golf swing practice device having the separable bulge-and-socket shield according to the preferred embodiment incorporated therein; 
       FIG. 2  is a top view of the preferred golf swing practice device; 
       FIG. 3  is a partial front and left perspective view of the separable bulge-and-socket shield according to the preferred embodiment, in an extended mode; 
       FIG. 4  is a bottom view of the preferred golf swing practice device showing an anchor groove and an anchor bar incorporated therein for retaining, and for setting different tensions in, the elastic cord. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   While this invention is susceptible of an embodiment in many different forms, there is shown in the drawings and will be described in details herein one specific embodiment of a separable cord shield and a cord tensioning arrangement for a golf swing practice device. The present disclosure is to be considered as an example of the principles of the invention and is not intended to limit the invention to the embodiment illustrated and described. 
   Although efforts have been made to limit the use of precise dimensions and exact geometric qualifiers, some narrow expressions remain in this disclosure and are used for convenience only to provide a better understanding of the present invention. Such dimensions and shapes can vary from one model of golf swing practice device to another. Therefore the dimensions and geometric expressions mentioned herein should not be considered as being absolute and limiting. 
   Referring to  FIGS. 1–3 , the golf swing practice device  20  according to the preferred embodiment comprises a floor pad  22  on which is mounted a hollow tee  24 . A golf ball  26  is set on that tee. The ball  26  is held to the pad  22  by an elastic cord  28  fastened to the ball  26  and to the pad  22 . The cord  28  extends through the tee  24  and through the pad  22  and is fastened to the bottom surface of the pad, as it will be explained later. When the ball is struck, it travels only a short distance and is pulled back onto the tee  24  by the elastic cord  28 . 
   A number of sensors (not shown) may be incorporated into or over a target surface  30  of the pad  22 , to record the direction and distance travelled by the ball  26  at every strike. Circuitry, instrumentation and a micro-controller (not shown) may be provided to emit audible signals or to generate audible messages through speakers (not shown) in response to signals from the sensors, to indicate a theoretical distance and direction of travel of the ball at every strike. The speakers are preferably mounted in a speaker compartment  32  in a forward region of the pad  22 . A bumper  34  is preferably provided on a forward edge of the target surface  30 , to protect the speaker compartment  32  from strong shots. 
   Details of the switches and circuitry incorporated in the preferred golf swing practice device are not provided because these details are not the focus of the present invention. These details are known to those skilled in the art of electronics. 
   The tee  24  has a hollow cylindrical stem  36  and a spherical socket  38  on its lower end. The floor pad  22  has a spherical bulge  40  thereon, through the centre of which the elastic cord  28  extends. The spherical bulge  40  has a slot  42  therein enclosing the strike side of the cord  28 . The slot  42  has an open side facing a forward direction toward a target surface  30  of the pad. 
   Preferably, the hole (not shown) in which the cord  28  extends through the pad  22  has large fillets on its ends. The radii of these fillets should be at least as much as the cord&#39;s radius. 
   The inside radius of the socket  38  is substantially a same dimension or slightly larger than the outside radius of the spherical bulge  40 , such that the socket  38  sits easily but precisely over the spherical bulge  40 . 
   In use, an initial tension is set in the elastic cord  28  to pull the socket  38  of the tee  36  firmly against the spherical bulge  40  as shown in  FIG. 1 . When the ball is struck, the tee  24  tilts over in the direction of the swing, and separates from the bulge  40 . The ball  26  accelerates away from the tee  24 . 
   If the ball is struck low, on the stem  36  of the tee for example, the tee  24  is forced to climb up the bulge  40  or to tilt about the bulge  40  thereby changing the direction of the impact force on the cord from horizontal to vertical, whereby the elastic cord  28  is not subject to large shearing forces at a point where the cord  28  exits the pad  22 . These shearing forces are largely absorbed and dissipated by the sliding motion of the socket  38  over the bulge  40 . 
   After the force of the swing has been diverted upward by the tee  24 , the tee  24  slides away along the cord  28 , following the ball  26 , such as in the movement of a regular tee. Because the tee  24  separates from the bulge  40  during a strike, it has little effect on the swing of the club. 
   A set of two or more tees  24  each having a different height is preferably provided with each practice device  20  such that a user can install whichever tee is more appropriate to the type of golf club that will be used during a practice session. 
   In order to further prevent shearing stresses on the socket-and-bulge arrangement and on the elastic cord  28 , a ramp  44  has been provided on the surface of the floor pad  22 , on the strike side of the bulge  40 . The purpose of this ramp  44  is to raise a club head during a swing, at least a slight distance from the pad  22  to prevent very a low shot that might cut the surface of the socket  38 , or otherwise strike the surface of the socket at a right angle. 
   A semicircular groove  46  is also provided in the surface of the pad  22 . The groove  46  is centred on the spherical bulge  40 , on the forward side of the bulge  40 . The purpose of this groove  46  is to catch and tilt the tee  24  back onto the spherical bulge  40  when the ball  26  returns to its striking position. 
   When the ball  26  returns to its initial position after a strike, the groove  46  on the pad  22  catches the rim on the socket  38  of the tee  24  and helps to tilt the tee  24  and the ball  26  back to their vertical alignment. Because of this groove  46 , the ball  26  and the tee  24  are efficiently tilted back to their striking positions with very little wobbling of the ball over the tee  24 . 
   Another important feature in the golf swing practice device according to the preferred embodiment is the ability to adjust the cord&#39;s tension according to the experience of a golfer, or according to a specific strike range with which a golfer wants to practice. This feature will be explained while making reference to  FIG. 4 . 
   In  FIG. 4 , the bottom surface  50  of the floor pad  22  is illustrated. A U-shaped groove  52  is provided in this bottom surface. The U-shaped groove  52  encloses a tail portion of the elastic cord  28 . This U-shaped groove  52  has hills and valleys therein (not shown) and one or more retaining tabs  54  through which the cord  28  is threaded and held, as it is customary with cord retention systems. An anchor key  56  is mounted across the U-shaped groove  52  and is fitted into a transverse slot  58  extending across the U-shaped groove  52 . The key  56  forces the cord into a vertical bend to further retain it, as it is also customary with cord retention systems. 
   The cord has graduation marks  60  on it at equally spaced intervals. The key  56  constitutes a gauge against which the graduation marks  60  can be read. An adjustment in the tensioning of the elastic cord  28 , with the 1 mark against the key  56  corresponds to a strike range of 100 yards for example, when the ball hits the “WOW!” region on the striking surface  30  of the pad  22 . Other adjustments correspond to strike ranges of 200, 300 or 400 yards for example. 
   As to other manner of usage and operation of the present invention, the same should be apparent from the above description and accompanying drawings, and accordingly further discussion relative to the manner of usage and operation of the invention would be considered repetitious and is not provided. 
   While one embodiment of the golf swing practice device according to the present invention has been illustrated and described herein above, it will be appreciated by those skilled in the art that various modifications, alternate constructions and equivalents may be employed without departing from the true spirit and scope of the invention. Therefore, the above description and the illustrations should not be construed as limiting the scope of the invention which is defined by the appended claims.