Abstract:
A practice putter for improving a golfer&#39;s putting game having a conventional grip attached to a conventional shaft. The shaft is connected to a head having a concave bottom surface of a predetermined radius. One or more balls are mounted in the bottom surface on an axle, and each ball revolves freely only in the direction of the axle. Each ball is positioned adjacent opposed sides of the concave middle portion. Each ball is mounted on an axle having a shock system that allows the ball to be pushed inward towards the head with the application of a predetermined force thereon. The length of the shaft is adjustable, and the angle determined by the top surface of the head and the shaft is also adjustable. In proper use, each ball is made to contact the putting surface as the head is moved in a straight line guided by the rolling balls.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention pertains to a golf putter. More specifically, the invention concerns a practice golf putter for improving a golfer&#39;s putting stroke. 
     II. Description of the Prior Art 
     A conventional golf putter typically includes a shaft and a head having a flat hitting surface. The head and shaft are arranged whereby a right-handed user would hit the ball with a conventional swing from right to left. The conventional design of putters positions the bottom edge of the hitting surface at ground level. There is a tendency for the ground to interfere with a desired stroke if contact is made with the ground. Thus when putting on a green, the user typically raises the putter slightly so that the hitting surface does not touch the putting surface usually referred to as the green. Many different types of golf putters have been developed for improving one&#39;s putting stroke. 
     One such golf putter is U.S. Pat. No. 5,207,721 issued to Lobdell. Lobdell teaches a putter having an elongated head with an axle adapted for supporting a pair of coaxial rotatable wheels. The wheels are used to roll the putter in the direction of a sight line extending outwardly from the shaft. The hitting surface has a convex radius and the ball is stroked by pushing the shaft toward the ball. A disadvantage of this putter is that a user cannot utilize the conventional left to right putter swing with this putter. 
     Another putter is U.S. Pat. No. 4,688,799 issued to Johnson which teaches a putter having a rotatable circular roller mounted on either the toe or the heel of the golf club. The roller prevents friction with the ground by raising the head so that the hitting surface does not touch the green in a stroke. A disadvantage, however, is that the single roller does not improve the straightness of one&#39;s putting stroke. 
     Another putter is U.S. Pat. No. 3,319,964 issued to Steinburg. Steinburg teaches a practice putter having an axle extending across the head parallel to the hitting surface and having a rotatable wheel on each end of the axle. The wheel raises the hitting surface above the green and allows straight putting strokes. A disadvantage is that the putter head is raised above the ground at the level according to the radius of the wheel. As such, the practice putter is disadvantageous in teaching the user to develop a putting stroke having an ideal spacing between the head and the green. 
     None of the prior art teaches an improved putter as taught by the present invention. 
     Thus, it is a primary objective of the present invention to provide a practice putter which can improve a golfer&#39;s ability to determine the level of height above the ground to hold his putter in a putting stroke. It is another objective of the present invention to provide a practice putter which can improve a golfer&#39;s ability to develop a straight putting stroke. Another objective of the present invention is to provide a practice putter which can be adjusted to be similar to a golfer&#39;s regular putter. 
     SUMMARY OF THE INVENTION 
     The present invention is a practice putter for improving a golfer&#39;s putting game. The golfer first uses the practice putter of the present invention to develop his putting stroke. The golfer can use the same putting stroke used with the practice putter using his own game putter to maximize the accuracy of his putts. 
     To assist the golfer in switching from the practice putter to the game putter, the practice putter emulates many of the standard features of conventional putters. The practice putter has a conventional grip attached to a conventional shaft. The shaft is connected to a head having a bottom surface, top surface, and one or more hitting surface orthogonal to the top surface. The head-shaft angle is the angle formed by the top surface of the head and the shaft. Different golf clubs have varying head-shaft angles. Also, the length of the putters differs among various putters. It is important that the head-shaft angle and length of the practice putter closely resemble that of a golfer&#39;s game putter. Thus, both the length of the shaft and the head-shaft angle of the practice putter are adjustable. 
     In a putting stroke, it is important to maintain the head at a constant level of height above the putting green. Furthermore, the putting stroke should be a straight sweeping motion. To assist the golfer develop this motion, the head comprises at least two balls mounted in the bottom surface, which protrudes outwardly therefrom. Each ball is mounted on an axle so that it revolves only in the direction perpendicular to the hitting surface. Also, each ball is mounted to move inwardly with the application of a predetermined amount of pressure thereon by a shock system. Furthermore, the bottom surface of the head has a concave middle portion and, each ball is preferably positioned adjacent the opposed ends of the concave middle portion. To use the practice putter properly, the bottom surface of each ball must be touching the putting surface at all times as the head is rolled along the green in a straight line toward the target golf ball. The middle portion is concave at a predetermined radius so that the hitting surface will ideally strike the center of mass of the golf ball when the practice putter is used properly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described, by way of example, and illustrated in the accompanying drawings of a preferred embodiment in which: 
     FIG. 1 is a side view of the putter of the present invention; 
     FIG. 2 is a cross-sectional side view of the head and shaft portion of the present invention cut along the A—A line of FIG. 4; 
     FIG. 3 is a front view of the present invention; and 
     FIG. 4 is a perspective view of the head and shaft portion of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows the putter  10  of the present invention. The putter  10  comprises a shaft  12  of the conventional shape and has a first end  14  attached to a grip  16  and a second end  18  attached to a head  20 . The head  20  has a bottom surface  22 , top surface  25 , and one or more hitting surface  27  orthogonal to the top surface  25 . When striking a golf ball (not shown), the hitting surface  27  is used to make contact with the golf ball. The head  20  comprises at least two balls  30  mounted in the bottom surface  22  and protruding outwardly therefrom as shown in FIG.  4 . Each ball  30  is mounted on an axle to revolve only in the direction perpendicular to the hitting surface  27 . As such, when utilized by a right-handed or left-handed golfer swinging the putter  10  from left to right and right to left respectively, each ball  30  would roll only from left to right and right to left. 
     As illustrated in FIG. 2, each ball  30  is mounted in the bottom surface within a chamber  33  defined in the head  20 . Each chamber  33  has dimensions predetermined to accommodate a housing member  35 . Each housing member  35  has an axle  37  for passing through and rotatably holding a ball  30 . Each ball  30  protrudes outwardly from the bottom surface  22  and is prevented from exiting out of the corresponding chamber  33  by a shoulder portion  39  along the edges of the bottom surface  22  at the entrance to the chamber  33  which engages the bottom edges  40  of the corresponding housing member  35 . Furthermore, each ball  30  predetermined amount of pressure thereon by a shock system. In the embodiment as shown in FIG. 2, the shock system comprises one or more springs  45  connecting the chamber  33  to the top surface  47  of the corresponding housing member  35 . Each spring  45  is biased to urge the housing member  35  away from the chamber  33 . In an alternative embodiment not shown, each axle  37  is removably attached to the housing member  35  so that the golfer could use the putter  10  with all of the balls  30  removed should he desire. 
     As shown in FIGS. 2 and 4, the bottom surface  22  of the head  20  of the present invention has a middle portion  48  which is concave. In the embodiment as shown in FIGS. 2 and 4, each ball  30  is positioned adjacent the opposed ends  47  of the concave middle portion  48 . 
     The putter  10  of the present invention further comprises a means to adjust the length of the shaft  12 . In a first embodiment (not shown), the means is a telescopic means whereby a first portion (not shown) of the shaft  12  can slide in and out of a second portion (not shown, of the shaft  12  having a slightly larger diameter. In the embodiment as shown in FIGS. 2 and 4, the means includes a hollow tubular member  50  hingeably mounted in the top surface  25  of the head  20 . The tubular member  50  has a diameter larger than the diameter of the shaft  12  for allowing the second end  18  of the shaft  12  to slide in and out of the tubular member  50 . A plurality of holes  54  extends through the tubular member  50  for engaging with a semi-spherical member  55  mounted in the second end  18  of the shaft  12 . The semi-spherical member  55  is biased to protrude outwardly from the shaft  12  and moves into the shaft  12  with the application of a predetermnined amount of force thereon. A spring loaded means, as known in the art, can be used in mounting the semi-spherical member  55  in the shaft  12 . Pushing the semi-spherical member  55  into the shaft allows the shaft  12  to slide in and cut of the tubular member  50 , and the shaft  12  locks into the tubular member  50  when the semi-spherical member  55  engages a corresponding hole  54 . Thereby, the length of the shaft  12  can be adjusted according to the hole  54  in which the semi-spherical member  55  is set. This feature allows the golfer to adjust the length to the practice putter  10  to that of his game putter. 
     The putter  10  further comprises a means to adjust the shaft-head angle defined by the shaft  12  and the head  20 . Such means requires a locking member for locking the tubular member  50  at predetermined angles relative to the top surface  25  of the head  20 . In the embodiment shown in FIGS. 2 to  4 , one or more plates  60  protrudes outwardly from the top surface  25  of the head  20  and is positioned adjacent the tubular member  50 . A plurality of holes  62  arranged in a predetermined arch pattern extends through at least one plate  60 . A second semi-spherical member  65  is mounted in the tubular member  50  corresponding to the holes  62  on the plate  60 . The second semi-spherical member  65  is biased to protrude outwardly from the tubular member  50  and moves into the tabular member  50  with the application of a predetermined amount of force thereon. A spring loaded means, as known in the art, can be used in mounting the second semi-spherical member  65  in the tubular member  50 . Pushing the second semi-spherical member  65  Into the tubular member  50  allows the tubular member  50  to be rotated, and the tubular member  50  can be locked into the desired angle relative to the head  20  by engaging the second semi-spherical member  65  to the corresponding hole  62 . Thereby, the angle of the shaft  12  relative to the head  2 D can be adjusted according to the hole  62  in which the second semi-spherical member  65  is set. This feature allows the golfer to adjust the shaft-head angle of the practice putter  10  to that of his game putter. 
     The putter  10  of the present invention further comprises a sight line (not shown) extending along the top surface  25  orthogonal to the striking surace. The sight line assists the golfer to develop a straight putting swing when hitting a target ball. In a putting motion, the sight line should move straight. 
     The putter  10  assists the golfer develop the ideal flat, straight, sweeping putting swing. In use, the right-handed golfer holds the putter  10  by its grip  16  and swings the head  20  from right to left in order to strike a target ball. Each putter  10  has a “sweet spot” on the hitting surface  27 . This is the spot usually on the central portion  70  of the hitting surface  27  that the golfer wants to hit the golf ball with in order to produce the most accurate result. In an ideal put, the “sweet spot” makes contact with the golf ball&#39;s center of mass. On the putter  10 , the “sweet spot” is centrally located on the hitting surface and corresponds to the deepest concave portion  75  of the bottom surface  22 . To properly use the putter  10 , it is necessary to roll the head  20  across the putting surface on the freely rotating balls  30 . The balls  30  guide the head  20  to move in a straight line. Furthermore, the balls  30  assist the golfer to maintain the head  20  at the proper level above the putting surface. When held above the putting surface, the bottom portion  77  of each ball  30  protrudes approximately ¼″ to ⅜″ from the bottom surface  22 . It is necessary for the golfer to have each surface  22 . It is necessary for the golfer to have each ball  30  touch the putting surface and freely rotate in a putting swing. The bottom surface  22  is concave so that if one or more balls  30  is not touching the putting surface as the head  20  strikes the target ball, the golf ball&#39;s center of mass will miss the “sweet spot”, producing an inaccurate put. The deepest concave portion  75  of the bottom surface  22  is set approximately ¼″ to ⅜″ from the level of the non-concave portion of the bottom surface  22 . Also, the head  20  should be made of a dense and heavy material such as a metal alloy which makes the head  20  relatively heavy compared to the head of a conventional putter. As such, if the golfer does not provide any lift to the head  20  to the desired level, the balls will not support the head  20  at the desired level of ¼″ to ⅜″ above the putting surface. Instead, if no lift is provided, the weight of the shaft  12  and head  20  on the balls  30  will cause them to press into head  20  causing the head  20  to lie too close to the putting surface and also causing the balls  30  to not roll properly. Providing the right amount of lift to the head  20  to maintain it ¼″ to ⅜″ off the putting green will allow the balls  30  to roll properly during the entire putting stroke. 
     To properly utilize the putter  10  of the present invention, the golfer maintains his normal stance and putting motion. In a back stroke (when the head is swung away from the golf ball), the golfer should provide the right amount of lift to the head  20  to allow the balls  30  to maintain contact with the putting green during the entire back stroke. Then in the front stroke (when the head is swung toward the golf ball), the golfer should also provide the right amount of lift to the head  20  to allow the balls  30  to maintain contact with the putting green during the entire front stroke. If done properly, the balls  30  will guide the head to roll in a straight line during both the back stroke and the front stroke. Even though the head  20  is rolling on the balls, the shock system and the rounded bottom shape of the balls  30  help to create a fluid, free-floating swing motion. Although it is preferred that the freely rotating balls  30  maintain contact with the putting surface throughout the back stroke and front stroke, it is understood that in longer putts where the golf ball is far from the target flag, it may be necessary to momentarily lift the balls  30  above the putting surface near the end of the back stroke and for a short time into the forward stroke without loosing much of the advantages of the present putter  10 . 
     When the average golfer properly practices using the practice putter  10 , his putting accuracy should be maximized when he switches to his own game putter. Also, by removing the balls  30  by detaching the axles  37 , the golfer can use the putter  10  of the present invention as his game putter. 
     While a preferred embodiment of the invention has been described and illustrated for purposes of clarity and example, it should be understood that many changes, substitutions and modifications to the described embodiment will be apparent to those having skill in the art in light of the foregoing disclosure without departing from the scope and spirit of the present invention which is defined by the claim which will follow.