US 20040242342 A1
A golf putter includes a putter head having an error variability reducing insert that imparts proportional damping properties such that the distance accuracy problems of conventional golf putters are statistically reduced. Through the use of a proportional damping insert comprising at least one exterior striking layer in combination with at least one interior proportional damping layer, the golf putter increases forward distance control by decreasing the distance error consequences of putting swing force errors. The statistical advantage of an error variability reducing insert having proportional damping properties results in missed putts, on average, ending up closer to the hole as compared to conventional putter designs. The exterior striking layer can have a hardness exceeding the level required by the United States Golf Association.
1. A golf putter comprising:
a shaft including a grip at a first end; and
a putter head attached to a second end of the shaft, the putter head having an error variability reducing insert having an exterior striking surface and at least one interior proportional damping layer.
2. The golf putter of
3. The gulf putter of
4. The golf putter of
5. The golf putter of
6. The golf putter of
7. The golf putter of
8. The golf putter of
9. An error variability reducing putter insert comprising:
a striking surface; and
at least one damping layer in proximity to and behind the striking surface,
wherein the error variability reducing putter insert is adapted to attach to a putter head such that the striking surface can strike a golf ball.
10. The error variability reducing putter insert of
11. The error variability reducing insert of
12. The error variability reducing putter insert of
13. The error variability reducing putter insert of
14. The error variability reducing putter insert of
15. The error variability reducing putter insert of
16. The error variability reducing putter insert of
17. A method of constructing an error variability reducing putter comprising:
attaching a error variability reducing insert to a putter head, the error variability reducing insert comprising a striking surface and at least one damping layer, the error variability reducing insert attaching to the putter head such that the striking surface can contact a golf ball when the putter is swung and the at least one damping layer is behind the striking surface to dampen a compression impact.
18. The method of
 The present application claims priority to U.S. Provisional Application No. 60/471,053 entitled, “GOLF PUTTER WITH ERROR VARIANCE REDUCING INSERT,” filed May 16, 2003, and herein incorporated by reference in its entirety.
 The invention relates generally to a golf putter. In particular, the invention relates to a golf putter having an error-variance-reducing hitting surface that is constructed to dampen the impact force of a golf ball by specific proportions over the typical range of forces commonly used in putting the ball.
 Throughout the history of golf, various techniques have been used to enhance and alter the hitting characteristics of golf club heads. There are many different head designs, which are intended to alleviate some of the most common swing problems or are specifically tailored for situations a golfer can encounter on a golf course. In addition, a player's physical characteristics, for example, height, weight, build, stroke mechanics, stance, gender, left-handed or right-handed, along with course conditions such as grass conditions, and moisture content, are also factors in determining how an individual will hit a putter.
 Golf club heads, including inserts for at least a portion of the desired striking area, have been used at least as far back as the 1880s, when leather-faced irons were manufactured in Scotland. Golfers in the 1890s were able to purchase putters with faces composed of gutta percha. More recently, inserts composed of various materials in a variety of shapes have been put forth by the golf industry to provide golfers with purported better feel and control of the golf ball.
 Many putter heads made today have what is commonly referred to as a “face insert,” which is placed in a desired impact area on the club head face to provide a certain feel when striking a golf ball. Face inserts may be formed of polymers such as polyurethane while the remaining portion of the putter head is typically formed of a metal such as steel or bronze. Generally, a cavity having a desired shape and depth is provided in the impact area on the putter head face. The face insert is installed in the cavity by either one of two well-known methods. In one method, synthetic resin in a liquid state is poured into the cavity and is then cured so that the face insert is tightly bonded to the cavity. In another method, the face insert is preformed and glued into the cavity by using a suitable adhesive such as epoxy. In both methods, the putter head may be milled after the face insert has been installed to provide a flat face across the club head. A drawback of both of these methods is that they are time consuming and costly.
 The development of insert materials has lead artisans to try and use such materials to develop putter heads that provide better putting results. In the United States, the only constraint guiding selection of potential insert materials is the United States Golf Association (USGA) rule that the striking surface of a putter insert be fairly hard (90 durometer or more on the Shore A scale). Although one finds many suggestions encompassing a wide variety of materials and constructions to improve the feel and accuracy of ball striking, these ideas have no actual basis in research or derivation from accepted science to support claims of actual improvement in putting performance.
 The material used for face inserts in conventional putters is usually a metal or a polymer. The softer feel attributed to some of these materials is preferred by some golfers for various reasons. Most often, golfers suggest that the softer feel increases comfort and results in less vibration when striking the ball. It has been suggested that the softer feel when putting may increase putting accuracy in some way though there has been no actual basis or research to support such a claim. Alternatively, putters have been designed for a harder feel, with the idea that increased vibration from ball impact may help putting accuracy in some way.
 U.S. Pat. No. 4,793,616, issued to Fernandez describes a club head, which is constructed of a molded lightweight composite material. The design is intended to provide improved weight and mass distribution for better ball striking. As disclosed, the invention does nothing to improve compression or feel.
 U.S. Pat. No. 5,403,281 describes a shock-absorbing casing of a magnesium alloy and an elastic plate of an aluminum alloy, a titanium alloy or a ceramic material. This elastic plate is fastened to an open end of the hollow casing such that the elastic plate forms the ball striking surface of the club head. The shock absorbing elastic plate of this invention does not control compression impact or the feel associated with striking the golf ball.
 U.S. Pat. No. 5,340,107 describes a putter of silicon nitride, and construction technique for the same. The putter does not have a layered hitting area, does not control compression impact and does not control the feel of striking the golf ball.
 U.S. patents by Huggens (U.S. Pat. No. 4,156,526) and Douglass (U.S. Pat. No. 5,083,778) disclose how the shape of the insert response may reduce lateral deflection off the striking face of a putter insert. These inventions both suggest that an elliptical-shaped insert is optimal for controlling the direction of ball-rebound off the face, however, these elliptical inserts do not relate to distance control or improved feel.
 Several patents, such as Webb (U.S. Pat. No. 6,270,423), Delaney (U.S. Pat. No. 6,001,030) and Rohrer (U.S. Pat. No. 6,431,997) describe clubs with interchangeable face pads and face inserts that an individual golfer can change himself to influence the feel of the club. However, these inserts do not address distance control.
 While a variety of prior art references have been discussed and mentioned, there has yet to be introduced a golf putter hitting surface that demonstratably improves the forward distance accuracy problems associated with putting a golf ball. The history of golf putter designs, as well as patents disclosing various golf putter designs, reveals no prior mention or awareness of designing a putter head that demonstratably increases putting accuracy through the application of proportional impact damping to reduce putting distance error variability. As such, there is a present need to provide for a golf putter that applies the physics of proportional impact damping to improve distance accuracy associated with golf putting.
 The golf club of the present invention goes beyond the past and current artisanship of simply trying differing materials for ball striking components to improve the feel of the golf putter. Instead, the present invention provides a demonstratable way of increasing putting accuracy through the use of materials selected to have proportional compression damping characteristics such that the overall error variance associated with putts is reduced.
 The golf club of the present invention reduces forward, line-of-sight distance accuracy problems found in conventional golf putters. Through the use of proportional damping materials under a hard hitting surface, a golf putter provides a damping effect on ball rebound that is proportional to the ball striking force. By varying the construction techniques and selected materials, a proportional damping insert can be configured to have a specific Error Variability Reduction (EVR) profile. The EVR effect is produced by damping hard striking forces more than light striking forces, with the damping effect being proportional to the striking force. The consequence of proportional damping is an increase in forward distance control by reducing the variability of a set of distance measurements around their mean. The proportional damping insert decreases the variability of the distance measures around their mean by the damping proportion of the damping insert, for example EVR proportion=damping proportion. Consequently, missed putts will, on average, end up closer to the hole than is the case with conventional golf putters.
 In one aspect, the present invention comprises a golf putter having an EVR insert. The EVR insert comprises at least one internal proportional damping layer and a hard hitting surface. The internal proportional damping layer can comprise a foam material, such as a vinyl or urethane foam, while the hard hitting surface comprises a material sufficiently hard enough to pass the USGA hardness test. An Ultra High Molecular Weigh (UHMW) polyethylene is one example of a polymer suitable for use as the hard hitting surface. The golf putter further comprises a putter head in which the EVR insert can be fixedly or removably mounted. The golf putter further comprises a shaft attached to the putter head.
 In another aspect, the present invention comprises a putter head having an EVR insert. The putting head includes a cavity for fixedly or removably mounting the EVR insert to the putter head. In an embodiment including a removable EVR insert, a backplate can be used to retain and mount the EVR inset in the putter head.
FIG. 1 is a side perspective view of a putter in accordance with the present invention;
FIG. 2 is a top perspective view of a putter head in accordance with the present invention;
FIG. 3 is a front perspective view of a putter head in accordance with the present invention;
FIG. 4 is a top view of a putter head in accordance with the present invention;
FIG. 5 is a top sectional view of the club head;
FIG. 6 is a graph illustrating an Error Variability Reducing profile for various Error Variability Reducing Inserts of the present invention;
FIG. 7 is a front side view of an embodiment of a golf putter with a configurable EVR putter head;
FIG. 8 is a rear side view of the golf putter of FIG. 7;
FIG. 9 is a rear side view of a head cavity within the golf putter of FIG. 7;
FIG. 10 is a front perspective view of the head cavity within the golf putter of FIG. 7;
FIG. 11 is a rear perspective view of the head cavity within the golf putter of FIG. 7;
FIG. 12 is a top perspective view of an embodiment of an EVR insert assembly;
FIG. 13 is a top section view of the EVR insert assembly of FIG. 12;
FIG. 14 is a top section view of a configurable EVR putter head;
FIG. 15 is a top section view of an embodiment of an EVR insert assembly;
FIG. 16 is a rear view of an embodiment of a backplate;
FIG. 17 is a rear view of an embodiment of a backplate; and
FIG. 18 is a rear view of an embodiment of a backplate.
 Referring to FIG. 1, an embodiment of a golf putter 10 in accordance with the present invention is shown. The putter 10 includes a shaft 12 having a top end 14 and a bottom end 16. Shaft 12 can be constructed of any of the industry standard shaft materials, for example, stainless steel, graphite or other composite materials. Shaft 12 includes a hand grip 18 located at top end 14. Operably attached to bottom end 16 of shaft 12 is a putter head 20.
 As depicted in FIGS. 2, 3 and 4, head 20 includes a front side or face 22, a rear surface or heel 24, a forward surface or toe 26, a rear side 28, a bottom surface 30 and a top surface 32. Located on face 22 is a proportional EVR insert 34. Bottom surface 30 has a slightly arcuate shape from face 22 to rear side 28 for the purpose of avoiding accidental grounding of head 20 during a swing as well as to reduce dragging of head 20 on the ground surface. Top surface 32 includes an alignment groove 36 in perpendicular alignment with the plain of face 22. In the present invention, alignment groove 36 has a width 38 greater than is typical in current putter designs. Alignment groove 36 is further accentuated through the application of a highly visible coating 40. Coating 40, most typically paint, is chosen to distinguish from the color of head 20. Typical colors for coating 40 can include white, yellow and orange though other colors having similar distinguishing characteristics can be used as well. The body of head 20 can be constructed of any of the common materials currently used in golf putters such as aluminum, bronze, nickel, steel, titanium and other suitable materials.
 Referring to FIG. 5, an EVR insert 34 comprises a multi-layer configuration including an outer striking surface 42 and at least one proportional damping layer 44. Striking surface 42 can comprise a variety of materials such as stainless steel, bronze, nickel, titanium or suitable polymers. In one embodiment, an Ultra High Molecular Weight (UHMW) polymer, for example UHMW polyethylene with a molecular weight of between 3 million and 6 million can be used. In a preferred embodiment, striking surface 42 is selected to meet a minimum hardness requirement of 90 durometer or greater on the Shore A scale as dictated by rules of the United States Golf Association. Proportional damping layer 44 typically comprises a damping material and has no hardness requirement. Examples of suitable damping materials include polymers and polymeric foams. In an embodiment, a proportional damping layer 44 can comprise a vinyl or urethane foam such as those manufactured by Aero Specialty Composites of Indianapolis, Ind. or Rogers Corp. of Woodstock, Conn. Proportional damping layer 44 can also comprise a plurality of layers, each layer imparting its own damping characteristic. In one embodiment, striking surface 42 and proportional damping layer 44 have material properties that allow for quick and permanent bonding, for example through the use of thermal processes, adhesive processes, molding processes or other suitable bonding processes.
 Generally, face 22 includes a recess 46 in which EVR insert 34 is inserted and attached. Attachment of EVR insert 34 within recess 46 can be permanent through adhesive, thermal or pressing means or EVR insert 34 can be removable attachable through the use of screws or other suitable fasteners. In the case of EVR insert 34 being removably attached with in the recess 46, a user can alter the proportional damping properties of putter 10 by swapping a first EVR insert with a second EVR insert having an alternative damping proportion.
 In use, a golfer grips putter 10 using the handgrip 18. The golfer aligns himself, the putter 10 and the ball relative to the target, most commonly a golf hole. Using alignment groove 36, the golfer positions the face 22 in a perpendicular arrangement to the desired line for the putt. The golfer then swings the putter 10 with a generally parallel swing such that EVR insert 34, and more specifically the striking surface 42, contacts the ball and propels it toward the hole. While the use of putter 10 is simple to describe, putting a golf ball consistently and accurately is one of the most difficult skills to acquire when learning the sport of golf. Consistency is difficult as many variables such as putt length, body mechanics, green contours, weather conditions and course conditions make each putt different.
 Through the use of a multi-layer design including proportional damping layer 44, EVR insert 34 has a proportional damping characteristic that is proportional to the impact energy supplied by putter 10. Statistically, the use of EVR insert 34 including the proportional damping characteristic reduces overall distance variability of putts around a target as compared to typical solid metal putters or putters having hard polymer inserts that lack proportional damping qualities.
 An EVR insert 34 can be constructed to exhibit optimum proportional damping qualities at a desired range of putt distances, for example 10-20 feet. Similarly, a maximum EVR effect for EVR insert 34 can be constructed specifically for short putts, mid-range putts and longer putts. Even when putt distances are outside the design range of EVR insert 34, a damping effect will occur that reduces the effects of common swing mistakes such as those typically encountered with very short putts.
 In actual use, an EVR insert 34 can be constructed using a specifically selected proportional damping layer 44 to impart an overall damping proportion of 0.30 or other desired damping proportions. In other words, the impact energy imparted to the golf ball through the EVR insert 34 is reduced by 30% over the desired range of putt distances. A golfer with a 30% EVR putter will have to hit the ball 30% harder to hit the ball comparatively the same distance than when using a putter without any proportional damping qualities. Golfers readily adjust their swings to compensate for a required increase in impact energy as they routinely make similar adjustments to putter weight, green speeds, wet greens and other environmental variables that are experienced between golf courses.
 Referring now to FIGS. 7 and 8, an alternative embodiment of a golf putter 200 including EVR properties is depicted. Similarly to putter 10, golf putter 200 includes a shaft 202 having a top end 204 and a bottom end 206. Shaft 202 includes a handgrip 208 located at top end 204. Operably connected to shaft 202 at bottom end 206 is a configurable EVR head 210.
 As illustrated in FIGS. 7, 8, 9, 10 and 11, configurable EVR head 210 comprises a head body 212 and an EVR insert assembly 214. Head body 212 is generally defined by a top surface 216, a bottom surface 218, a front surface or toe 220, a rear surface 222, a front side 224 and a rear side 226. As shown in FIGS. 10 and 11, a head cavity 228 extends between front side 224 and rear side 226. Head cavity 228 is defined by a top cavity surface 230, a bottom cavity surface 232 and a pair of side cavity surfaces 234 a, 234 b, a front opening 236 and a rear opening 238. Front opening 236 is undersized as compared to rear opening 238 such that a front cavity surface 240 surrounds the perimeter of front opening 236. Front cavity surface 240 includes a pair of head bores 242 a, 242 b extending into head body 212 such that the head bores 242 a, 242 b do not extend to the front side 224. Head bores 242 a, 242 b can include an internal thread or other suitable attachment means.
 As illustrated in FIGS. 12 and 13, EVR insert assembly 214 comprises a striking layer 244, a proportional damping layer 246 and a backplate 248. Striking layer 244 has a striking surface 250 projecting from a flange surface 252. Striking surface 250 is sized and shaped to fit snugly within front opening 236. Proportional damping layer 246 is constructed to have a perimeter equivalent to flanged surface 252. Backplate 248 has a plate surface 254 and a pair of projecting arms 256 a, 256 b. Projecting arms 256 a, 256 b include arm flanges 257 a, 257 b and insert bores 258 a, 258 b. Projecting arms 256 a, 256 b and plate surface 254 are dimensioned to snugly accommodate the striking layer 244 and the flange surface 252 of striking layer 244. Projecting arms 256 a, 256 b are dimensioned such that the distance between insert bores 258 a, 258 b corresponds to the distance between head bores 242 a, 242 b.
 To assemble EVR head 210, EVR insert assembly 214 is positioned such that striking surface 250 fits within front opening 236 as shown in FIG. 14. When properly positioned, striking surface 250 and head body 212 form the substantially smooth and uninterrupted front side 224. When striking surface 250 is positioned within the front opening 236, flange surface 252 and arm flanges 257 a, 257 b are in contact with front cavity surface 240 such that head bore 242 a is aligned with insert bore 258 a and head bore 242 b is aligned with insert bore 258 b. Finally, a pair of fasteners 260 a, 260 b, such as a pair of screws, is directed into the insert bores 258 a, 258 b and subsequently into head bores 242 a, 242 b to operably couple the EVR insert assembly 214 and the head body 212.
 Due to the ability to attach and remove the EVR insert assembly 214 from the head body 212, it is possible for a golfer to specifically configure the golf putter 200 to have a desired EVR profile, for example High Gain EVR, Low EVR profile or High EVR profile. A golfer can replace a first EVR insert assembly with a second EVR assembly wherein the second EVR insert assembly has a selected proportional damping layer 246 different from that of the first EVR insert assembly. In another alternative embodiment, a golfer could replace EVR insert assembly 214 with EVR insert assembly 262 illustrated in FIG. 15 such that the proportional damping layer 246 is replaced with a first damping layer 264 and a second damping layer 266. In another alternative embodiment, the EVR properties of the EVR insert assembly 214 can be specifically tailored by removing mass from the plate surface 254 as shown in FIGS. 16, 17 and 18. As shown, a plurality of perforations 268, such as channels or spheres, can be fabricated as part of plate surface 254.
 In order to illustrate the effect of proportional impact damping on putt length variability, an experiment is conducted in which a golfer hits 10 twelve-foot putts with a standard hard (either metallic or polymer) striking surface. The golfer fails to make any of the putts but instead, the putts are distributed around the hole, half being long and half being short. With respect to the distribution, the average length is twelve feet, the range is 8 feet and the standard deviation is 2.74 feet as shown in Column A of Table 1 below.
 When the same 10 golf balls are putted with a proportional damping putter having a damping proportion of 0.30, the corresponding putt lengths and variability are as indicated in Column B of Table 1. Note that the measures of putt average, putt range and putt deviation are 30% less than the values displayed in Column A.
 The average length of Column B putts is only 8.4 feet, which is 3.6 feet short of the required 12 foot required putt length. However, this is not the expected result of using a proportional damping putter. Instead, golfers quickly adapt and learn to hit an EVR putter harder, just as golfers quickly learn to swing harder on slower greens as opposed to fast greens, to swing harder on wet greens as opposed to dry greens, and to swing harder with a light putter as opposed to a heavy putter.
 Column C shows the results wherein a golfer using a proportional damping putter hits the 10 twelve-foot putts 30% harder, on average, than with the standard metal or polymeric faced putter. The average 30% increase in swing force required to distribute the 30% damped putts around the 12 foot target results in an average of 3.6 feet being added to putt lengths shown in Column B to produced the distribution of putts in Column C. Note that the variability measures of the Column C putts are 30% less than the original putts in Column A. Thus, hitting putts harder as required by an EVR putter, does not reduce the accuracy gained with using the EVR putter.
 Quantitatively, putting accuracy with an EVR putter improves by ρ, on average, over putting accuracy with a comparable non-EVR putter where accuracy is measured by standard deviation, where Sc=1−ρ (SA).
 SC: Standard deviation of putts with a proportional damping putter
 SA: Standard deviation of putts with a comparably non-EVR putter
 ρ: The damping proportion.
 A second experiment was conducted as described above with putters having different damping constructions to illustrate that using different damping materials results in EVR putters with differing EVR profiles. FIG. 6 presents EVR measurements for the three EVR insert configurations used in the experiment.
 The experiment was conducted using a putting machine programmed with seven putting force levels. Each of four putters hit eight matching golf balls at each force level. The putters were identical in construction with respect to putter length, head weight and striking surface. The putting machine hit the golf balls on a moderately fast putting green with a green speed stimpmeter reading of 11.3 feet. The only variable between each of the four putters was the insert construction as described below:
 Putter 1: A putter similar to putter 10 including an insert consisting of a UHMW polyethylene striking surface meeting the USGA hardness standard.
 Putter 2: A putter similar to putter 10 including an insert with the same striking surface used in Putter 1 backed with a 0.03 inch thick layer of urethane foam (Part Number 4701-50-30031-04, produced by Rogers Corp. of Woodstock, Conn.).
 Putter 3: A putter similar to putter 200 including an insert with the same striking surface used in Putters 1 and 2 backed with a 0.03 inch thick layer of less dense urethane foam (Part Number 4701-30-25031-04, produced by Rogers Corp. of Woodstock, Conn.), and with the insert backplate cut-out in the fashion depicted in FIG. 16.
 Putter 4: A putter similar to putter 10 including an insert with the same striking surface used in Putter 1, 2 and 3 backed by a 0.03 inch thick layer of soft urethane foam (Part Number 4701-30-25031-04, produced by Rogers Corp. of Woodstock, Conn.).
 The EVR profiles displayed in FIG. 6 indicate the EVR obtained at the impact force levels required to propel a golf ball the distances indicated on the abscissa. EVR data points for the EVR putters were determined at a given impact force level by comparing the error variance (standard deviation) for a given EVR putter with the error variance (standard deviation) for the standard putter and plotting the percentage difference (error variance reduction) at that level. Best fit trend lines were drawn through the data points for each putter/insert configuration and are shown in FIG. 6 for each configuration.
 The EVR of each of the EVR inserts was determined at a given impact force level by comparing the average ball distance travel produced by the damping inserts as compared to the average ball distance travel produced by the standard non-EVR insert at that same force level. The procedure was repeated at each of the seven force levels, producing the EVR profiles for each of the four putter as shown in FIG. 6. A best-fit trend line was drawn through the data points for each insert configuration. These trend lines are also shown in FIG. 6.
 The EVR profile for Putter 2 presents a generally linear decreasing EVR, from 9% at 4.5 feet to 3.5% at 18.4 feet.
 The EVR profile for Putter 3 shows a steep rate of EVR decrease from 18% at 4.5 feet to 9% at 12 feet and then a shallower linear decrease to 4.5% for putts at 18.4 feet.
 The EVR profile of Putter 4 shows a rate of EVR decrease accelerating from 16% at 4.5 feet to 7% for putts at 18 feet.
 The results shown in FIG. 6 demonstrate the feasibility of designing putters with differing EVR profiles. The EVR profiles for Putters 2, 3 and 4 in FIG. 6 show the greatest accuracy gain for short and medium length putts. These particular EVR profiles would be most helpful to golfers who have trouble with short distance putts. More specifically, Putter 3 would be the most helpful for golfers who jerk or yip their stroke on short putts.
 In addition to the EVR profiles demonstrated with Putters 2, 3 and 4 of FIG. 6, putter inserts that that produce level or increasing EVR with increasing putt lengths can be created by layering materials with different damping characteristics.
 The present invention has been described above with reference to a preferred embodiment. However, those skilled in the art will recognize that changes and modifications may be made to the preferred embodiments without departing from the spirit and scope of the present invention.