Golf putter

A golf putter has a clubhead that includes a ball striking surface defined by a curved concave surface over which a coating material has been applied. The outer surface of the coating material is substantially flat. The coating material is selected according to desired functional characteristics and hardness.

FIELD OF THE INVENTION

This invention relates to golf clubs, and more specifically to a putter having an improved club head design for improved putting accuracy.

BACKGROUND OF THE INVENTION

In the game of golf, putting of the ball, either on or off the green, requires a shorter more controlled stroke or swing than other golf shots. A shorter, more controlled swing helps to assure more accuracy and controlled contact with the ball, which in turn increases accuracy of the shot and decreases the likelihood of a mis-hit. It is also often said that putting is one of the single most important aspects of the game. Certainly it is true that missed putts can add significantly to a player's score. Therefore, improvements in a player's putting game can be a significant part of lowering overall scores.

There are numerous putter designs that are intended to improve a player's putting game and to decrease their scores. One such improvement is described in U.S. Pat. No. 6,406,380, in which I am the named inventor, and which is incorporated herein by this reference. One embodiment of the putter described in the '380 patent includes a concave striking face that focuses the golf ball rebound trajectory as the ball travels toward the pin, thereby improving shot accuracy.

Despite the improvements in golf club design generally, and despite the specific improvements described my U.S. Pat. No. 6,406,380 there is an ongoing demand for golf clubs that help improve the quality of the game.

The present invention is directed to an improved golf putter design that incorporates a curved concave ball striking face that is coated with a compound having specified properties. The ball striking face of the putter, defined by the outer surface of the coating material adhered to the curved face, is substantially planar. Nonetheless, the coating material retains some elasticity that imparts a dampening effect so that the desired effects of the underlying curved surface—namely focused ball trajectory—are retained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first preferred embodiment of a golf putter clubhead1according to the invention illustrated herein is shown inFIG. 1. In the embodiment ofFIGS. 1through4, two principal body sections define putter clubhead1, a ball striking plate2and a rearward-extending tail portion3. As may be seen inFIG. 2, the ball striking plate2is generally semi-circular and includes a sole4formed on the lowermost periphery of the ball striking plate2in such a position that the plane of the sole4lies parallel to the turf5when the putter is in the normal position for striking the ball. That is, sole4is a flattened or beveled section formed on the lowermost periphery of the ball striking plate that allows for a smooth putting stroke without effecting the symmetry or concentricity of the clubhead, as described below. As visible inFIG. 2, the outer opposite edges of striking plate2along sole4may be beveled upwardly relative to the plane of turf5. Thus, sole4includes two beveled sections20,22, which preferably are beveled upwardly at an angle of about 10° relative to the plane of turf5, which is defined herein as the ground plane. The beveled sections20and22allow for variations in the way that the golfer holds the club so that the ball striking face6contacts the ball in the desired position with each stroke.

Clubhead1may of course be manufactured as either a right-handed or a left handed club. Thus, a right handed clubhead1is shown inFIGS. 1,2and4, and a left handed clubhead1is shown inFIG. 3.

Ball striking plate2has opposed front and rear surfaces. The forward-facing surface of ball striking plate2is defined as that portion of the putter that is presented to the golf ball when the clubhead actually makes contact with the golf ball, and is labeled in the figures with reference number6. This forward facing surface is sometimes therefore referred to as the ball striking surface of clubhead1. The rearward-facing surface7of the ball striking plate2is opposite the forward-facing surface.

As used herein, forward is the direction that a golf ball travels relative to the putter when the ball is stroked, and other directional terms such as rearward, upward, etc. are defined relative thereto. It will be understood that like structures in the drawings are labeled with the same reference numbers.

Tail portion3of clubhead1extends from the rearward-facing surface7of ball striking plate2. Tail portion3is preferentially cylindrical in cross sectional shape and defines a longitudinal axis8extending along the length of the tail portion generally transverse to the plane of the ball striking plate when the ball striking plate is vertical relative to the ground plane. The forward facing surface6of ball striking plate2is substantially flat and defines a plane that is substantially normal to longitudinal axis8, although as noted below in some instances the plane of the forward facing surface6may be angled to provide some measure of loft if desired. This may be done by tilting the ball striking plate2relative to the longitudinal axis8through tail portion3, or by machining the forward surface of the striking plate to provide angular loft. A neck9for attachment of a club shaft10is formed on the tail portion3and defines a neck axis11. Neck axis11is normal to and radiates from longitudinal axis8through tail portion3, and as shown inFIG. 2, is angled relative to a vertical axis by about 20°, although the angle of the shaft10may be varied according to desire. Clubhead1has a center of mass12that preferably lies on and is coincident with longitudinal axis8. Preferably, neck axis11intersects longitudinal axis8at the center of mass12of the clubhead1.

It should be noted that the length of shaft10may be varied to change the style of the club, yet while still incorporating the clubhead1described herein. For example, the shaft may be of the type used for standard putters or may be relatively longer for use with so-called belly putters and the like. Additionally, the handle grip applied to the upper end of the shaft may be of any type, such as the relatively long, “dual grip” used in pendulum type putters.

With reference toFIG. 2it may be seen that the tail portion3of the clubhead1is concentric with longitudinal axis8, and that neck axis11is coincident with and intersects longitudinal axis8. The distance from sole4to longitudinal axis8is labeled with distance line X, which for purposes herein is slightly less than the radius of a golf ball to accommodate some ground clearance between sole4and turf5during a normal swing. It will be appreciated therefore that when a golf ball is stroked by the clubhead1moving through a normal stroke with sole4moving closely over turf5, the ball striking face6makes contact with the ball at approximately an equator of the ball. The intersection of longitudinal axis8with the forward-facing surface6thus defines a ball-contacting area in which the center of mass of the clubhead is effectively concentrated and centered. Assuming that the point of contact between the ball striking face6and the ball is approximately at the intersection of the axis8and the ball striking face6, the directional control during putting is improved.

With reference toFIG. 3, it may be seen that a guide indicator or dimple14is formed or printed on the upper radial surface of striking plate2in a position such that a vertical line transverse to the ground plane bisects the dimple when the clubhead is in a position such as would normally occur when a ball is being stroked. The dimple14thus acts as a visual guide for the golfer to align the putter clubface.

In the embodiment ofFIGS. 1 through 4, the mass of ball striking plate2is relatively less than the mass of tail portion3. Therefore, it will be appreciated that the size of the semi-circle defined by ball striking plate2(FIG. 2) may be increased or decreased without materially altering the concentration of mass of the clubhead. For instance, the size of the ball striking plate may be decreased to approximately the size of a golf ball. As another example, the ball striking plate2could be sized such that it is essentially coextensive with the tail portion3.

Where desired, the total mass of the clubhead, and accordingly the swing weight of the club, could be varied without significantly affecting the clubhead balance and symmetry. This may be done by removing material, core17, concentric with the longitudinal axis8through tail portion3. Such displaced material could be left as a void or filled with a material dissimilar to the material used to form the clubhead, and of dissimilar density, to attain the desired swing weight. The balance and weight of the clubhead may also be adjusted by removing material from other locations, such as at void15formed in rearward facing surface7.

As noted above, the forward-facing surface6of ball striking plate2may be tilted slightly relative to longitudinal axis8to create loft. The degree of tilt of the forward-facing surface6may be varied according to preference, but preferably would not be more than about 5° from vertical. Although forward-facing surface6may thus be tilted relative to longitudinal axis8, the plane of the forward-facing surface of the clubhead remains substantially normal to longitudinal axis8. As used herein, the words substantially normal contemplate a loft angle of no more than about 5°.

Again, the preferred ball contacting area in the embodiment shown inFIGS. 1 through 4, which may be approximated as the point where longitudinal axis8intersects forward-facing surface6, is where the center of mass of the clubhead is effectively concentrated and centered in a normal golf stroke. Although not shown in the drawings, the forwardmost edge13of sole4, that is, that portion of sole4that lies adjacent turf5when the club is in use, may be tilted, beveled or radius slightly to facilitate a smooth putting stroke. The contour of forwardmost edge13is variable according to preference.

The ball striking surface6will now be described in detail. As noted above, and as illustrated in the drawings, the forward facing surface6defines a substantially flat or planar surface. However, it may be seen that the forward facing surface is defined by a multi-layered structure having an outermost surface (defined as ball striking surface6) that is planar, and an underlying or backing surface6′ that, as illustrated inFIGS. 1 through 4, is regularly concavely curved. More particularly, in the embodiments illustrated inFIGS. 1 through 4the forward-facing portion of backing surface6′ is formed as an arc section of a sphere having a spherical radius16having its center on the longitudinal axis8of the tail portion3. During manufacture of clubhead1, backing surface6′ is formed with the desired spherical radius, for example by milling the ball striking plate2or, if the clubhead1is cast, by forming an appropriate mold. The length of radius16determines the radial curvature of backing surface6′, and may be varied but ideally would correct for mis-hits, off the longitudinal axis8on longer putts. The radial surface thus focuses the ball rebound trajectory back to the longitudinal axis8at the center point of the radius. The length of such radius16, and thus the curvature of backing surface6′ may be varied widely according to desire. One preferred length of radius16is between about 5 to 10 feet. It will be appreciated that where radius16is in the preferred range of between about 5 to 10 feet, the radius shown in drawingFIG. 4is exaggerated for the purposes of illustration. Moreover, the radius16may be different from the preferred ranges just noted so long as the beneficial effects of the curved backing surface6′ is maintained.

After the backing surface6′ has been formed in the forward facing surface of striking plate2, a surface coating30is then applied over the curved backing surface6′. Surface coating30is preferably a polymer material such as polyurethane that may be applied over backing surface6′ as a liquid, and which bonds permanently to the backing surface. After the liquid coating30has dried and/or cured, the hardened coating30is ground, milled or otherwise flattened so that the forward facing portion of the surface is flat, as illustrated, to thereby define an outer, flat ball striking surface6. Stated another way, the coating material is ground until forward facing surface6is planar. Although in the drawings the coating30is shown extending to the periphery of backing surface6′, the coating need not be applied over the entire surface of backing surface6′. Stated another way, the ball striking surface6may be defined by a flattened portion of coating30that is applied to only a portion of the surface of backing surface6′. The ball striking surface6may optionally include face markings if desired.

It will be appreciated that the coating material30described above when coated onto the curved backing surface6′ defines a plano-convex lens, which, owing to the elasticity of the coating material30, focuses the ball trajectory as the ball rebounds off the flat portion of the lens, the planar ball striking surface6. A plano-convex lens has a planar interface on one side and a convex interface on the opposite side. In optical applications, such lenses may be used to focus, collect and collimate light along a principal axis through the lens. With respect to the present clubhead1, the rearward facing surface of the coating material30, that is, the surface that is adhered to curved backing surface6′ defines the convex portion of the plano-convex lens, and the forward facing surface of the coating material, that it, ball striking surface6, defines the planar portion of the plano-convex lens. The longitudinal axis8is analogous to the principal axis through a plano-convex lens.

The functional effect of the coating material30that defines a plano-convex lens having specified hardness is that the trajectory of a golf ball rebounding off the ball striking surface6is focused onto a point on the longitudinal axis8. The distance that the point lies from the ball position when it is struck is defined by the length of radius16.

The material used for coating30is selected for its ability to provide some elasticity, yet retain a durable, hard surface. Numerous coating products are commercially available that are suitable for use herein. Coating30is preferably a polymer such as a polyurethane, although numerous polymers having the characteristics noted herein are commercially available from a variety of suppliers. As noted, coating30must have some elasticity yet must have desired hardness and durability. One measure of these characteristics is the durometer hardness of the coating material, which often is expressed in terms of durometer A and durometer D scales. The durometer hardness of the material selected for coating30is important because the relative hardness of the coating30directly effects the manner in which a golf ball rebounds off of ball striking surface6. Preferably, the durometer hardness of the material selected for use in coating30is in the range of between about 80 durometer A to about 75 durometer D, and more preferably about 90 durometer A.

Various materials may be used to form clubhead1, including for example various grades of stainless steel, aluminum, bronze, brass or ceramics, or combinations of these materials. The clubhead may be manufactured by conventional means, including milling, casting and molding. Regardless of the material used or the manner in which the clubhead is formed, the material used for coating30must be selected so that a permanent bond is formed between the material used in ball striking plate2, and coating30.

As noted, forward facing surface6is flat and backing surface6′ is curved. When the material used for coating30has durometer hardness in the range noted above, the ball striking face define by surface6has some elasticity so that when a golf ball is stroked with clubhead1, the trajectory of the ball is influenced by the curvature of backing surface6′, even though the forward facing surface6that makes contact with the ball is flat. Stated another way, although the ball striking surface6is flat, the relative elasticity of coating30allows the beneficial ball trajectory focusing effect attributable to the curved backing surface6′, as described above, to be retained.

Although not shown in the Figures, the backing surface6′ of ball striking plate2may alternately be formed as an arc section of a cylinder prior to coating with coating30. The longitudinal axis through such cylindrical arc section would be preferably oriented normal to the plane defined by the sole4, and would be positioned such that it intersects with the longitudinal axis8through the tail portion3. The radius could be variable but again ideally would correct for mis-hits, off the longitudinal axis8on longer putts, and would focus the ball rebound trajectory back to the clubhead axis at the center point of the radius. Such radius16for a radially formed backing surface6′ that defines a cylindrical arc section might ideally be about 5 to 10 feet.

Thus, the backing surface6′ may be defined by an arc section of a sphere or an arc section of a cylinder, and in either case the backing surface6′ is defined by a regularly curved concave surface.

Certain alternative configurations and structures may be made to the foregoing embodiments without effecting the invention. For example, while the preferred cross sectional shape of tail portion3is circular, the tail portion3could be formed in other cross sectional configurations, such as triangular or square, while maintaining the center of mass of the clubhead along a longitudinal axis through the tail portion.

Turning now to the embodiment illustrated inFIGS. 5 through 7, it may be seen that a putter according to the present invention may be formed without the tail section3. With reference to those figures, the clubhead1may be formed with opposed ball striking surfaces6and24, on both sides of the shaft10. The first ball striking surface6is defined by a backing surface6′ that is formed as described above with reference toFIGS. 1 through 4so that it is a curved concave surface, for example, either a spherically radially formed surface or a cylindrical section having radius16. A coating30as detailed above is applied to backing surface6′ and after the coating has cured, the coating is ground so that forward facing surface6is flat. The opposite side of ball striking plate2is likewise defined by a curved concave backing surface24′ that is coated with a coating30that is ground to define a flat surface. The result is a clubhead1that has opposed ball striking faces6and24, each of which is flat but coated with a polymer that provides the benefits of the curved surface underlying the flat ball striking face. An ambidextrous player may use this type of a putter, as illustrated with arrow32depicting the direction of putter movement for a left handed putt, and arrow34depicting the direction of movement for a right handed putt. The swing weight of the clubhead1shown inFIGS. 5 through 7may be varied by removal of material from ball striking plate2, as illustrated with core sections26, which may be left as voids or filled with materials having a mass dissimilar from the other materials used in the clubhead.

It is understood that the above discussion and details of the preferred embodiments and drawings are exemplary of the present invention and that changes in structure and configuration of golf putters may be effected without departing from the scope of the present invention and equivalents as defined in the following claims.