DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0040] Referring to FIGS. 1 - 10 , the putter construction according to the present development is shown. Putter head 20 includes a face member 22 , a body member 24 , and a back weight member 26 , each of which are secured together as will be discussed. A shaft bore 28 is provided for attachment of putter head 20 to a club shaft.

[0041] As shown in FIGS. 2 - 4 , face member 22 has a generally flat ball-striking front portion 30 and a back portion 32 . A recessed region or back cavity 34 is formed in back portion 32 , and preferably has a generally cylindrical contour. A pair of recessed wing portions 36 are formed at opposite ends of back cavity 34 , creating a keyway that preferably has a depth less than the maximum depth of back cavity 34 . A hole 40 is formed in each wing portion 36 for receiving a threaded fastener. Preferably, back cavity 34 is substantially symmetric about line ALI, which is also generally parallel to the ground.

[0042] Turning to FIGS. 5 - 6 , in one embodiment of the present invention, an insert 42 is provided for coupling body member 24 to face member 22 . Insert 42 includes a central, generally cylindrical projecting portion 44 , along with a base portion 46 which creates a keyed portion that is adapted to be received within wing portions 36 of back cavity 34 of face member 22 . A generally cylindrical, tapered portion 45 is also provided, and serves as a further keyed region for aiding in insertion of insert member 42 into body member 24 . More particularly, the overall longitudinal geometry of insert 42 is cylindrical, such that it can rotate in at least one plane or direction within body member 24 as will be described shortly. Base portion 46 includes a pair of holes 50 , which preferably include recessed portions 51 so that the head of a screw or other fastener may be recessed therein.

[0043] The loft of the putter is defined as the angle of the face and a line perpendicular to the sole line measured to a point that is half of the distance of the face height and located on the center of the face. In order to provide adjustment of the loft, the angle of body member 24 related to face member 22 is adjusted by rotation within cylindrical back cavity 34 of face member 22 . With an insert member 42 disposed in body member 24 , and with base portion 46 disposed within wing portions 36 , the loft may be changed to a suitable amount.

[0044] More particularly, with reference to FIGS. 8 - 10 , body member 24 is generally rectangular and hollow, and includes cylindrical front portion 52 , back portion 54 , and side portions 56 , 58 . Front portion 52 receives an insert member 42 in cylindrical passage 53 . Front portion 52 further includes a slit 55 extending along the length of cylindrical passage 53 , and thus providing a loose fit of insert member 42 when placed in cylindrical passage 53 , which runs parallel to line ALI when front portion 52 contacts back cavity 34 . During setting of the desired loft, body member 24 , with an insert member 42 housed in passage 53 , is loosely coupled to face member 22 . With the insert member 42 resting in wing portions 36 , the body member 24 may be rotated with respect to face member 22 ; the body member rotates about insert member 42 , which is fixed in location and angle with respect to face member 22 . When a desired loft has been set, the insert member 42 may be tightly coupled to face member 22 using screws or other fasteners, which extend through holes 50 , 40 in insert member 42 and face member 22 , respectively. In addition, the rotation of body member 24 with respect to insert member 42 may be arrested through the use of a threaded fastener that extends through threaded hole 57 and connects opposing portions of front portion 52 separated by slit 55 . When the fastener is tightened, the separation between these portions may be decreased such that the gap provided by slit 55 is closed. In turn, the diameter of passage 53 is slightly decreased, locking insert member 42 in place.

[0045] A side flange 66 is provided on a side 56 , 58 , depending on whether the golfer is right-handed or left-handed. A shaft bore 28 for receiving a club shaft extends at least partway through flange 66 , which is oriented at an angle α with respect to a flat edge 68 of body member 24 . Preferably, angle α is between about 5° and about 85°. The desired loft may be set by rotating body member 24 with respect to face member 22 .

[0046] As shown in FIG. 9 , edge 68 is disposed opposite an edge 78 of body member 24 . Edge 78 includes straight potions 80 , 82 which are crooked with respect to each other. Preferably, straight potions 80 , 82 are disposed at an angle β between about 0° and about 30°.

[0047] Body member 24 also includes bores 70 through side walls 56 , 58 . Weight removed from side walls 56 , 58 due to the presence of bores 70 may be redistributed in putter head 20 , such as with back weight member 26 as shown in FIG. 1 . Further to this end, a hole 72 is provided in back portion 54 of body member 24 so that back weight member 26 with a similarly disposed hole 74 may be secured thereto, as with a fastener such as a screw. More than one hole 74 may be provided so that several fasteners may be used. Preferably, back weight member 26 is generally arcuate in shape, and is symmetrically disposed with respect to line CEN along the longitudinal center of body member 24 . Back weight member 26 may further include a central recessed region, so as to conform to the geometry of body member 24 .

[0048] FIG. 11 shows a top view of another putter head 100 of the present invention. FIG. 12 shows a rear view of putter head 100 . FIG. 13 shows a bottom view of the putter head 100 . Club head 100 is designed to have a high moment of inertia MOI. Putter head 100 includes a face member 110 , a body member 120 , and a weight member 130 .

[0049] Face member 110 is elongate, with the length being greater than the width. The width of face member 110 may be substantially uniform along its length (there may be an inset for seating body member 120 ). Face member 110 has a generally flat ball-striking front surface 112 , a rear surface 114 , and a bottom surface 115 . Rear surface 114 may contain holes 116 for inserting weights 117 . Preferably, there is a hole 116 and a weight 117 toward each end of rear surface 114 . Face member 110 is preferably made of aluminum.

[0050] Front surface 112 has a leading edge 113 . Leading edge 113 is preferably beveled to create a smooth transition between face surface 112 and bottom surface 115 . Beveling reduces the likelihood of snagging the club on the ground, or “grounding” the club, during a putting stroke. Bottom surface 115 may also be angled at ends thereof to further reduce the likelihood of grounding the club in the event of a toe-up or toe-down stroke.

[0051] Face member 110 has a loft angle within a range of approximately 0° to approximately 10°. As used herein, “within a range” includes the end values. Face member 110 preferably has a loft angle of approximately 4° or less with shaft 140 in the vertical position. A 4° loft angle has been determined the ideal loft angle for a putting stroke. See the inventor's U.S. patent application Ser. No. 09/156,540, now pending and which is incorporated herein by reference, for further discussion regarding putter loft angle. The presence of weight member 130 and the location of the club head center of gravity CG behind face member 110 creates a dynamic loft angle effect, which causes the ideal loft angle to be less than 4°. The loft angle preferably is approximately 3.5° or less, and more preferably is approximately 3° or less. This angle may be varied according to the needs of the individual user. For example, if the user has a 2° forward press, face member 110 will be designed with a loft angle of 2° greater, resulting in the proper dynamic loft angle during use. Likewise, if the user has a rearward press, the loft angle of face member 110 can be reduced to produce the proper dynamic loft angle.

[0052] Body member 120 is coupled to rear surface 114 and extends away from rear surface 114 in a substantially perpendicular fashion. Body member 120 has a length and a width, the length being greater than the width. In a preferred embodiment, the length of club head 100 is substantially the same as the length of face member 110 . Body member 120 is coupled to face member 110 such that face member 110 is slightly lower than body member 120 . This encourages proper contact between strike surface 112 and the ball, and further minimizes the likelihood of grounding the club during the swing. Body member 120 is preferably made of aluminum.

[0053] The illustrated embodiment of body member 120 contains a plurality of holes 122 to reduce its weight. This gives body member 120 the appearance of having rails, and helps to increase the MOI, as discussed below. In an alternative embodiment, body member 120 contains no holes.

[0054] Body member 120 contains shaft mount 124 for connecting a shaft 140 to club head 100 . Shaft mount 124 may be positioned toward a side of body member 120 as shown in the figures, or it may be formed within the rectangular frame of body member 120 . For example, shaft 140 may be coupled to body member 110 within one of holes 122 . Shaft mount 124 is positioned behind face member 110 approximately at the midpoint along the length of body member 110 . This location, which is near the club head center of gravity CG, provides for a more flowing stroke. Shaft mount 124 may be positioned a distance Ls behind strike face 112 . Distance Ls is preferably approximately 1.5 inches to approximately 2 inches. Club head 100 has a length L having a midpoint MP. Shaft mount 124 may alternatively be positioned between midpoint MP and strike face 112 , and more preferably is positioned a distance of approximately 25% of putter head length L to approximately 50% of putter head length L behind strike face 112 .

[0055] Shaft 140 may preferably by bent to give a straight, no offset appearance at address. Shaft 140 is preferably coupled to produce a 71° lie angle. Shaft 140 may be of any standard length, including a length of approximately 35 inches or more. Alternate preferable lengths for shaft 140 include approximately 37 inches and approximately 53 inches.

[0056] Face member 110 and body member 120 are coupled to form a “T-frame” shape. In addition to increasing MOI, as discussed below, the T-frame allows for improved accuracy. During the putting stroke, body member 120 provides the user with a visual alignment of the putt. Any slight misalignment of club head 100 that may likely go unnoticed with a traditional putter may be readily apparent via the T-frame design of club head 100 . By aligning elongate body member 120 with the intended ball path, the user can ensure the putter is aligned as desired. By doing so, the user is more likely to hit the intended shot.

[0057] Weight member 130 is coupled to body member 120 at the opposite end from face member 110 . This placement of weight member 130 increases the MOI of club head 100 . Inertia is a property of matter by which a body remains at rest or in uniform motion unless acted upon by some external force. MOI is a measure of the resistance of a body to angular acceleration about a given axis, and is equal to the sum of the products of each element of mass in the body and the square of the element's distance from the axis. Thus, as the distance from the axis increases, the MOI increases. By placing weight member 130 at the distal end of body member 120 relative to face member 110 , MOI can be significantly increased without substantially altering the overall weight of club head 100 . This MOI increase is greater than that possible with heel-to-toe weighting of conventional putters, due to operational weight limits.

[0058] When a club, such as a putter, strikes a ball off-center, there is a tendency for the club to rotate about a vertical axis passing through the club head center of gravity CG. This club rotation causes the shot or putt to deviate from the intended course by either a push/pull (straight ball path), slice/hook (curved ball path), or combination thereof. Increasing the MOI about this axis, such as through use of weight member 130 , increases the resistance to club head rotation and creates more accurate off-center shots.

[0059] During an ideal putting stroke, the putter head is not rotated. That is, face member 110 is kept substantially perpendicular to the intended putt path. During actual putting strokes, however, golfers frequently rotate the putter about a vertical axis, resulting in the ball being sent awry. Increasing the MOI about the vertical axis passing through club head center of gravity CG also helps prevent this unintended and undesired rotation of club head 100 .

[0060] Club head 100 has a center of gravity CG. Center of gravity CG is the point at which the entire weight of club head 100 may be considered as concentrated. This is also the point through which club head 100 will rotate if a force not passing through center of gravity CG is exerted thereon. Moving center of gravity CG away from strike face 112 increases the MOI and stability of club head 100 . Center of gravity CG is preferably located a distance LcG behind strike face 112 . Distance LcG preferably is approximately 1 inch to 4 inches. More preferably distance LcG is approximately 1.5 inches to approximately 2 inches, and most preferably distance LcG is approximately 1.7 inches. Center of gravity CG is preferably between midpoint MP and weight member 130 . Center of gravity CG is preferably located a distance of approximately 50% of length L to approximately 75% of length L behind strike face 112 . Shaft mount 124 is preferably positioned between midpoint MP and strike face 112 , and more preferably is positioned a distance of approximately 25% of length L to approximately 50% of length L behind strike face 112 . Club head 100 has a weight. Approximately 50% of the weight to approximately 75% of the weight is located on a weight member side of shaft mount 124 . This positioning of center of gravity CG and shaft mount 124 , along with the weights of face member 110 , body member 120 , and weight member 130 , give club head 100 a MOI as measured about a vertical axis passing through center of gravity CG that is preferably greater than approximately 550 kg·mm ² . More preferably, the moment of inertia is within a range of approximately 600 kg·mm ² to approximately 800 kg·mm ² , and most preferably is within a range of approximately 700 kg·mm ² to approximately 750 kg·mm ² .

[0061] An off-center hit may also tend to make club head 100 rotate about shaft mount 124 . That is, the club tends to rotate about shaft 140 . The placement of weight member 130 , however, also tends to increase the MOI about shaft mount 124 more than is possible with heel-to-toe weighting of conventional putters. The MOI of club head 100 as measured about a vertical axis passing through shaft mount 124 preferably is greater than approximately 550 kg·mm ² . More preferably, the moment of inertia is within a range of approximately 600 kg·mm ² to approximately 900 kg·mm ² , and most preferably is within a range of approximately 800 kg·mm ² to approximately 850 kg·mm ² .

[0062] Another common problem resulting in misaligned putts is rotation of the club head through a horizontal axis substantially perpendicular to face member 110 . That is, about an axis collinear with the intended path of the putt. This toe-up or toe-down misalignment frequently occurs during the putting stroke. The position of weight member 130 and its arcuate design increase the MOI about the horizontal axis. Club head 100 preferably has a MOI as measured about a longitudinal axis of body member 120 that is preferably greater than approximately 200 kg·mm ² . More preferably, the moment of inertia is within a range of approximately 200 kg·mm ² to approximately 400 kg·mm ² , and most preferably is within a range of approximately 250 kg·mm ² to approximately 300 kg·mm ² .

[0063] Weight member 130 also helps produce more accurate results for on-center shots by helping the user “swing through” the ball rather than decelerating or “slapping” the ball. Since weight member 130 is separated from strike surface 112 by body member 120 , weight member 130 will be traveling downward (i.e., working with gravity) when club head 100 strikes the ball. This results in a smoother putting stroke, and a more accurate shot.

[0064] Placing weight member 130 further towards the rear of club head 100 increases the MOI, but also has the undesired effect of increasing instability. If weight member 130 is placed too far away from face member 110 , the club head can become “tipsy.” That is, placing weight member 130 too far back may cause club head 100 , when the club is placed on a level surface, to tilt backward. Thus, club head 100 must be designed to simultaneously maximize MOI and ensure adequate stability.

[0065] One way to achieve this balance is by using the proper ratio of the weight of weight member 130 to the overall weight of club head 100 . Weight member 130 preferably comprises at least 25% of the entire weight of club head 100 . More preferably, weight member 130 comprises at least 50% or at least 75% of the entire weight of club head 100 . Weight member 130 is preferably made of steel, which has a greater density than aluminum. In a preferred embodiment, weight member 130 has a weight within a range of approximately 100 g to approximately 200 g, and more preferably within a range of approximately 125 g to approximately 170 g. The overall weight of club head 100 preferably is within a range of approximately 200 g to approximately 600 g, and more preferably within a range of approximately 300 g to approximately 500 g. Alternatively, the overall weight of club head 100 may be similar to the weight of conventional club heads.

[0066] Stability of club head 100 is also increased by weights 117 in face member 110 . Stability may also be increased by bending weight member 130 such that its ends are curved toward face member 110 , as shown in the figures. The illustrated horseshoe shape moves the center of gravity WCG of weight member 130 forward, toward face member 110 , and provides a pleasing appearance for club head 100 . Weight member 130 is symmetrically disposed about body member 120 . The ends of weight member 130 may be curved forward to any desired amount, including such that it contacts face member 110 . The ends of weight member are preferably bent such that they are a distance Lwm from strike face 112 . Distance Lwm is preferably from 0 inch to approximately 1.5 inches, and more preferably from 0 inch to approximately 1 inch. Extending the ends of weight member 130 to face member 110 gives club head 100 a mallet-like appearance, which may be desirable to some golfers. In a preferred embodiment, weight member 130 has a circular cross section. Center of gravity WCG is located behind center of gravity CG, and is a distance LWCG from strike face 112 . Distance LWCG is preferably from 0 inch to approximately 3 inches.

[0067] While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein.

[0068] Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. For example, in an alternate embodiment, the mating portions of face member 22 and body member 24 may include a series of facets along a generally cylindrical shape, instead of smooth cylindrical surfaces. Such facets may provided a more positive engagement of the components during fitting. In addition, in another embodiment, body member 24 may be secured to face member 22 without an insert member 42 . Front portion 52 of body member 24 may be provided with projections that mate with wing portions 36 in face member 22 . Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.