Abstract:
Golf club putter that has a raised center of gravity, to allow hitting a golf ball at an improved spot. The raised center of gravity is done by either changing the shape of the putter head, or the material layout of the putter head.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the U.S. Provisional Application No. 60/130,734, filed Apr. 20, 1999 and application Ser. No. 60/156,642, filed on Sept. 28, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present-invention relates to improved putters with heightened center-of-gravity. 
     BACKGROUND AND SUMMARY 
     An important part of golfing is putting. Accurate putting requires attention to speed/distance and line. Speed/distance is controlled by the velocity and force applied to a ball, while line defines the direction of the moving ball. The line can only be made by the golfer, but the speed can be aided by a more consistent roll. 
     A top spin roll is generally most desired because it is less likely to be affected by bumps on the green which might otherwise effect the line of the ball. Many golf putter designs have attempted to aid the golfer in producing a moving ball that has an appropriate top spin roll. 
     It is an object of the invention to define a new design that facilitates this result. 
     Another problem with accuracy in putting is caused by ground interaction. A golfer usually lines up the putter with the ball (“at address”), brings the club back (“takeaway”), and then hits the ball and follows through. The desired results are obtained when the putter is kept exactly as the golfer intended it. However, the putter is usually touching the ground at address. During takeaway, the putter may interact with the ground (“ground interaction”). The golfer aims to keep the putter slightly above the ground during the rest of the takeaway and follow through. However, sometimes the putter does touch the ground. Even the most carefully manicured course includes some irregularities in its greens. This can affect the aiming of the putter, and hence effect the line of the ball. 
     In recognition of this problem, it is an object of another aspect of the present invention to reduce the amount of interaction between the club and the green. This is preferably done by reducing the surface area of the surface of the club that interacts with the ground, using a new technique. 
     It is often desirable to strike the golf ball near the center of gravity of the ball, i.e., its equator. The equator of a golf ball is usually around 0.75 inches off the ground, since a golf ball has a diameter of 1.5 inches. Another goal of the present invention is to aid the golfer in striking the ball at a consistent location. 
     The present invention features an improved golf putter which includes a pair of ground engaging surfaces attached to downwardly extending areas called herein runners. The runners include downwardly-extending feet which extend from the bottom surface of the putter head at the head&#39;s heel and toe. Each runner has a surface area which is less than the entire area of the bottom surface of the putter. The runner also has a height which depends on the shape and mass of the putter. The height can range from ⅛-⅝ inches. 
     During a stroke, this ground engaging surface becomes the lowermost area of the putter. If this surface does come into contact with the ground, the leading edge of the putter blade (“the blade”) is raised to a level which is slightly below the ball&#39;s equator. Since any putter generally does not touch the ground during a putt, the ball will be struck with an upward blow during a putting stroke. 
     This action facilitates imparting the desirable top-spin roll to the golf ball. 
     The runners also facilitate the blade striking the ball at a location that minimizes undesirable side spin or back spin which otherwise occurs when the ball is putt. 
     The present invention defines improved structural aspects and surfaces which reduce the surface area that usually would come into contact with the ground. This thereby reduces the chance of ground interaction. 
     The base of the runners of the present invention have a reduced ground engaging surface area, thereby reducing their interaction with the ground. The runners have a smaller surface area than the head itself to minimize interaction with the ground. The combined surface area of each runner can be in the range of 0.15-0.35 in 2 . The edge of the runners are preferably formed with a shape to further minimize interaction with the ground during a putting stroke, rounded, angled, or tapered. 
     The positions of the runners also allow the user to place or “set” the putter relative to the ball in a consistent, well-defined way. During the takeaway, the head is more consistently brought back and then moved forward along a straight path which is collinear with the desired path of the ball. This facilitates consistent, accurate putting. 
     As described above, a good putt involves proper speed and direction, including consistent speed and a desired direction from a straight takeaway and straight follow through. The present invention modifies speed by raising the blade, and modifies line by reducing the surface area. 
     Another aspect of the present invention uses an insert at the blade surface that is formed of a different material than the material of the remainder of the golf club. That material may, for example, have an elasticity which is similar to that of the covering of the golf ball (e.g., rubber or plastic). The insert makes it possible to strike the golf ball with a consistent force. The insert also produces a desirable “dead hit” which further facilitates accurate putting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the present invention will now be described in detail with reference to the accompanying drawings, in which: 
     FIG. 1A is a front view of an improved putter according to the invention; 
     FIG. 1B is a side view of the putter of FIG. 1A prior to contact with a golf ball; 
     FIGS. 2A-2D are side views of the putter of FIG. 1A, respectively, prior to being swung, during swinging, immediately prior to contact with a golf ball, and immediately after contact with the golf ball; 
     FIGS. 3A-3D are side views of a putter of the prior art, respectively, prior to being swung, during swinging, immediately prior to contact with a golf ball, and immediately after contact with the golf ball; and, 
     FIGS. 4A-4C show another embodiment of the invention which includes rounded edges on the putter; 
     FIGS. 5A-5C show a rounded embodiment with a shaft that fits outside the putter neck; 
     FIGS. 6A-6C show a crooked shaft putter embodiment; 
     FIGS. 7A-7C show an embodiment including specially shaped runners; and 
     FIG. 8 shows an embodiment which is optimized for use with heavy material; 
     FIGS. 9A-9D show a number of different putter head designs; and 
     FIGS. 10A and 10B show a specific putter head design. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1A and 1B respectively show front and side views of a first embodiment of a putter  10  according to the invention. The putter  10  includes a head  12  having a front face  14 , a shaft  18  which can include a handle or other elements allowing gripping the golf club, and a pair of runners  20 ,  21 . Each runner includes a front portion  15  which faces the ball  30 , and inside  36 , outside  31 , and back  37  portions. A ground engaging surface is formed from the lowermost surfaces of the runners in the general area  24 . 
     The putter has a heel end  21  and a toe end  23 . The first runner  20  is formed on the bottom surface of the head at the toe end  23  and the heel end  21 . Blade  25  is formed on front face  14  between the runners  20  and  21 . 
     The head  12  also includes side surfaces  50 ,  52  and rear surface  55 , and a bottom surface  57 . 
     The runners  20  and  21  raise the blade  25  of the putter  20  above a ground surface  22 . 
     The surface area of the ground engaging surfaces of the runners (indicated by the bracket  24 ) which contacts the ground  22  is smaller than the surface area of the bottom surface  57  of the putter head  12 . This system minimizes interaction between the blade and the ground during putting. The minimized interactions can reduce deflections of the putter. They also promote a firm top spin roll of the ball. The runners  20  and  21  also raise the blade  25  to a level which is slightly below the equator  32  of the ball  30  which allows more consistent putting pace which can contribute to speed. This helps the blade  25  to strike the ball  30  with an upward blow during putting. The upward blow imparts a desirable top-spin roll on the ball, and causes undesirable spin which tend to cause the ball to deviate from the desired path, such as back or side spins to be minimized. 
     The height and surface area of the runners are important design parameters in the putter head design. The height of the runner is shown as the arrow  27 . This height determines the location where the ball is struck. A golfer usually raises the putter off the ground slightly during a putt. A putt begins with the bottom of the club head on the ground, but the putter is raised above the ground at the moment when it strikes the ball. The inventor found it desirable to form the runners to have a height which is below the equator of the ball. 
     The runners  20 ,  21  preferably have a height between ⅛ inch and ⅝ inches, with a height of 0.30 inches being the most preferred. 
     The total surface area of the runners is chosen to provide a stable base on which to set the putter while minimizing contact between the head and the ground. The preferred surface area is between 0.15-0.35 square inches per runner for a total of 0.3-0.7 square inches. 
     The distance separating the runners (shown by the arrow  31 ) is preferably wider than a golf ball diameter (1.5 inches). Preferably, this distance is between 1.2 and 2.5 inches. Other preferred dimensions of the putter are described herein with reference to the further embodiments. 
     Each runner preferably includes a straight segment (arrow  42 ) and a curved, tapered, or angled segment (arrow  43 ) along the front vertical portion which faces the ball. Sharp edges are less preferred, as they tend to catch on the ground during putting, thereby disrupting the swing. The back portion  37  of the runner is similar to the front portion, and includes a straight segment and a curved, tapered, or angled segment. 
     Insert  33  is shown on the front face  12 . Insert  33  may be disposed between the two runners. As will become evident from investigation of the other embodiments, the insert is optional, and many usable embodiments omit using the insert. 
     The insert  33  includes a lower edge which is located even with the blade  25 . The insert  33  is preferably formed of a material different than the material of the putter head  12 . 
     Most preferably, the insert is formed of a material having some property which is similar to the material forming the outer covering of the golf ball. The insert  33  promotes a desirable “dead hit” when the ball is struck. Such a hit reduces vibrations during impact, minimizes the chances that the ball “jumps” off the front face of the putter head following impact, and, in general, provides the user with a more comfortable feel during putting. 
     The present invention preferably uses two runners. The putter is rested on the two runners prior to putting. During putting, the putter is easily drawn backwards from the rested position, and then pushed forward in a pendulum-type motion. The path along which the putter swings is generally collinear with the desired path of the ball. Conventional putters, in contrast, have a much larger bottom surface area. This creates a greater possibility that during takeaway or follow through that there may be risk of interaction with the ground. The present design is less likely to be thrown off line because there is less surface area interaction with the ground. Since the putter starts at rest on the ground and must be moved, interactions between the uneven ground and the putter surface must take place. 
     The inventor currently contemplates forming the putter of the present invention from the metallic glasses, as described in U.S. Pat. Nos 5,288,344 and 5,368,659. 
     FIGS. 2A-2D show different positions of the putter  10  relative to a golf ball  30  during a putting stroke. Prior to the stroke (FIG. 2A) the putter  10  is set so that the runners  20  rest on the ground  22 . The runners  20  elevate the blade  25  so that it is slightly below the ball&#39;s equator. The putter  10  is drawn back (FIG. 2B) and then pushed towards the ball. The bottom surfaces of the runners  20  are preferably above the ground  22  (FIG. 2C) as the ball is struck, if a good putting stoke is made. The blade  25  then impacts the ball  30  very near the ball&#39;s equator with an upward blow (FIG.  2 D). This causes the ball to roll away from the putter with a desirable top spin (indicated by the arrow  35 ) and along a path collinear with a path defined by the putters swing. 
     FIGS. 3A-3D show an analogous sequence of steps for a putter  50  of the prior art. Prior to the stroke (FIG. 3A) the putter  50  preferably rests with its blade  55  even with or slightly above the ground  57 . The blade  55  is typically just below the ball&#39;s equator. The putter  50  is then drawn back (FIG. 3B) and then pushed towards the ball (FIG.  3 C). The blade impacts the ball with the leading edge below the equator of the ball with a downward force (FIG. 3D) to generate backspin on the ball (indicated in the figure by the arrow  59 ), causing the ball to skid. The ball may eventually exhibit a top-spin roll, although this typically occurs after the ball has skidded for some small distance and deviated from its intended course. 
     Other embodiments include additional features. 
     FIGS. 4A-4C show an embodiment that has a rounded head  400 . The hozzle  402  of the head is sized to fit a shaft  405  around it. This embodiment includes a system which has no sharp edges on the putter—every edge is at least slightly rounded. The shaft fits around the outside of the hozel as shown. 
     The putter head  400  has a lower, runner area  410 , which is wider in dimension than the upper, shaft attaching area  420 . FIG. 4B shows a cross sectional view of the FIG. 4A rear view along the line  4 B— 4 B. FIG. 4C shows the front view of the putter. The runners in this embodiment are rounded along multiple axes, to form a rounded ground engaging surface. 
     FIGS. 5A-5C show another rounded embodiment—this one having a shaft which fits around the outside of the neck of the putter. The preferred dimensions of this putter are 2.2 cm by 12.2 cm overall with a 1 cm lip forming the blade area. 
     The FIGS. 6A-6C embodiment uses a crooked shaft. 
     FIG. 7A-7C shows an embodiment with runners that are less rounded than those of previous embodiments. 
     The FIG. 8 embodiment uses a special heavy material such as brass or bronze. 
     Other embodiments are within the scope of the invention. For example, runners can be included with any type of putter design. In addition, each dimension of the putter head depends on the types of materials used to fabricate the head. These dimensions can therefore be adjusted significantly for different types of putters formed from different materials. In particular, the dimensions are likely to decrease when more dense materials are used. 
     The runners described above have ellipsoidal cross sections. Alternatively, the runners can have triangular, cylindrical, circular, or any other type of cross-sectional area. The runners preferably include both flat and curved, angled, or tapered portions in all dimensions. For instance, all surfaces of the runner can be curved (e.g., the runner has a hemispherical shape). 
     The preferred embodiment of the invention features two runners. In other embodiments the putter can have a single runner. In this case, the runner has a similar shape as described above. In still other embodiments, the putter includes more than two runners, distributed periodically or randomly along its bottom surface. 
     Preferably, the putter head and the runners are formed together in a single cast. Alternatively, the runners can be attached to the putter head using, e.g., a weld or adhesive. Runners can be made on a putter having any shape or size which falls within guidelines of the United States Golf Association (USGA). 
     The angle of the putter&#39;s shaft has minimal affect on the design of the putter head and the runners. The shaft can be imbedded directly into the putter head. 
     The raising of center of gravity for most greater top spin of the golf ball while the previous embodiments have described one technique of raising center of gravity, additional techniques are described in the second and third embodiments described herein. 
     As above, raising the height of the blade can promote contact with the golf ball as close to the equator as possible. This also raises the center of mass in the putter to promote angular momentum that produces true roll. It creates a tendency to strike the ball with a leading edge to effect more consistent strikes without flyers. It also allows placing the blade flat on the putting surface. This provides for more consistent alignment of the putter blade and promotes a more consistent stroke. 
     When the blade meets the ball, all of the force vectors are resolved onto one point intersection between ball and blade. Underspin is generated when there is a component of force (or a resolved vector) that is oriented toward the putting surface. The type of spin should be a function of the direction of acceleration in which a putter approaches the ball, and also a function of the position of the center of mass with respect to the ball. To both promote a putting stroke with an upward force vector and position the mass in such a way as to generate more overspin and less underspin, the present embodiments raise the center of mass (C.O.M.). 
     FIG. 9A-9D show cross sectional views of a golf putter head of an embodiment that raises the center of gravity without the need for runners. In one embodiment, these features can be used without ground runners, i.e., they have a bottom-most surface that is substantially flat. Each of these heads has the common feature of a center of mass which is raised to a height above the center of the putter, and preferably above the center of the golf ball. 
     FIG. 9A shows a golf club head which is substantially constant in cross-sectional area from its top area  900  to its bottom area  902 . The golf club putter head is formed of two materials: a first more dense material area  904  formed of a first material and a second less dense material area  906  formed of a less dense material, and a separator  915  between the materials. Specific preferred materials are described in detail herein. 
     The center of mass  910  is defined by the density of the materials and the position of the separator  915  between the materials. According to this system, the center of mass is at a height H that is at least 55 percent of X where X is the total distance between the bottom surface of the bottom portion  902  and the top surface of the top portion  900 . H is also approximately ¾ inch, or a little greater than ¾ inch. 
     In this embodiment, preferably the area of the head does not differ in cross section between its top and its bottom by more than 20 percent. The raised center of gravity is formed by a denser material rather than a changed cross-section. 
     In one embodiment shown in FIG. 10A, the golf club head is formed of a lower half and a upper half. The density of the material of the upper half is preferably at least 5 percent more than the lower half. 
     The density (and hence mass) of the upper half of the golf club head in both FIGS. 9A and 10A is equal to between 105 percent and 170 percent of the density of the lower half. A value of 115 to 130 percent is optimal. 
     Exemplary materials are described herein. The denser materials (Group “H” materials) used on the top half  900  have a density greater than 6-7 grams/cc. Materials include, in order of denseness, stainless steel, copper alloy, such as copper beryllium, bronze, aluminum-bronze alloys, tungsten, lead, nickel, carbon steel, liquid metal, or regular steel. 
     The less dense materials (Group “L” materials) used in the lower portion  902  preferably have a density of less than 5 grams per cubic centimeter. These include, in order, wood, polymers such as Plexiglas (™) form of acrylic, liquid metal (U.S. Pat. No. 5,288,344) polydicyclopendadeyene (DCPD), carbon and carbon materials, aluminum, titanium, aluminum alloys, titanium alloys, and stainless steel. 
     As can be seen, the upper end of the less dense materials may overlap with the lower end of the more dense materials. 
     FIG. 10B shows this embodiment being coupled with ground runners as described with reference to FIGS. 1-8. Any of the ground runners can be used. In this embodiment, both altered center of gravity by materials, and by lifting the section itself, are combined. Again, H&gt;=0.55×, and H&gt;=¾ inch, the radius of a golf ball on the ground. 
     Another alternative for a golf club head shape is shown in FIG.  9 B. In this embodiment, the golf club head is formed to have a non-uniform cross-section and formed of a homogeneous material. The golf club head  920  is formed with a top half of the golf club  922  that takes up a larger volume than the lower half  921  of the golf club head  924 . The volume of the top is greater than the volume of the bottom by at least five percent. In this way, even though a homogeneous material is used, the relationship of H&gt;=0.55× and H &gt;=¾ inch is maintained. Again, preferably the mass of the top “half” of the head is between 105 percent and 170 percent of the mass of the bottom half, and more preferably 115 percent to 130 percent. The golf club head in FIG. 9B can be formed with a striking surface in area  924  and an overhanging portion  926  which overhangs the striking surface. The golf club head can be formed of any of the materials from groups A or B described previously. The head can also be formed with runners. 
     A third embodiment, shown in FIG. 9C, forms a golf club head  930  in any of the shapes described in any of FIGS. 1-9B,  9 D or FIG.  10 . The head can be formed of multiple materials, or formed of a single material and can be of any desired cross-section. The head is conceptually divided into top and bottom halves  932  and  934 . The top half includes a strip  936  of a heavy weight material, such as lead. The heavy weight strip of material changes the weight balance of the top portion relative to the bottom portion. In this way, the top half is caused to have between 105 percent and 170 percent of the weight of the bottom half; more preferably between 115 percent and 130 percent. Again, this can be formed with runners as in FIG.  10 B. 
     Another embodiment shown in FIG. 9D forms the golf club head with a bottom portion  942  that has a larger cross-section than the top portion  944 . The material of the bottom portion  942  is a less dense material from the group L materials. The material of the top portion  944  is a more dense material e.g. selected from the group H materials. While FIG. 9D shows these materials being functionally divided at their halfway point, it should be understood that the dividing line  946  between the bottom portion  942  and the top portion  944  could be at any portion in between those two portions. 
     All such modifications are intended to be encompassed in the following claims.