U.S. patent application number 10/846009 was filed with the patent office on 2004-12-02 for golf putter with error variance reducing insert.
Invention is credited to Patten, Richard L..
Application Number | 20040242342 10/846009 |
Document ID | / |
Family ID | 33457209 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040242342 |
Kind Code |
A1 |
Patten, Richard L. |
December 2, 2004 |
Golf putter with error variance reducing insert
Abstract
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.
Inventors: |
Patten, Richard L.;
(Minneapolis, MN) |
Correspondence
Address: |
PATTERSON, THUENTE, SKAAR & CHRISTENSEN, P.A.
4800 IDS CENTER
80 SOUTH 8TH STREET
MINNEAPOLIS
MN
55402-2100
US
|
Family ID: |
33457209 |
Appl. No.: |
10/846009 |
Filed: |
May 14, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60471053 |
May 16, 2003 |
|
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Current U.S.
Class: |
473/313 |
Current CPC
Class: |
A63B 53/0416 20200801;
A63B 53/0487 20130101; A63B 53/0425 20200801; A63B 53/0441
20200801 |
Class at
Publication: |
473/313 |
International
Class: |
A63B 053/02 |
Claims
What is claimed:
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 claim 1, wherein the exterior striking
surface has a hardness of at least 90 durometer on the Shore A
scale.
3. The gulf putter of claim 1, wherein the error variability
reducing insert is removably mounted to a cavity in the putter head
such that the error variability reducing profile can be selectively
configured by replacing the error variability reducing insert with
a second error variability reducing insert.
4. The golf putter of claim 3, wherein the error variability
reducing insert further comprises a backplate wherein the backplate
includes means for fastening the error variability reducing insert
to the putter head.
5. The golf putter of claim 4, wherein the backplate includes at
least one perforation for varying a backplate mass such that the
error variability reducing profile is modified.
6. The golf putter of claim 1, wherein the at least one
proportional damping layer comprises a foam.
7. The golf putter of claim 6, wherein the foam is a vinyl foam or
a urethane foam.
8. The golf putter of claim 1, wherein the exterior striking
surface comprises an Ultra High Molecular Weight polymer.
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 claim 9 further
comprising a backplate such that the error variability reducing
putter insert is removably attached to the putter head.
11. The error variability reducing insert of claim 10 wherein the
backplate includes at least one perforation for varying a backplate
mass such that a damping proportion is modified.
12. The error variability reducing putter insert of claim 9,
wherein the exterior striking surface comprises an Ultra High
Molecular Weight Polymer.
13. The error variability reducing putter insert of claim 9,
wherein the at least one damping layer comprises a polymeric
foam.
14. The error variability reducing putter insert of claim 13,
wherein the polymeric foam comprises a vinyl foam or a urethane
foam.
15. The error variability reducing putter insert of claim 9,
wherein the at least one damping layer comprises a first damping
layer and a second damping layer.
16. The error variability reducing putter insert of claim 9,
wherein the striking surface has a minimum hardness of 90 durometer
on the Shore A scale.
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 claim 17 further comprising removing and
replacing the error variability reducing insert with a second error
variance reducing inset to adjust a damping profile of the putter.
Description
PRIORITY CLAIM
[0001] 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.
FIELD OF THE INVENTION
[0002] 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.
BACKGROUND OF THE INVENTION
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
SUMMARY OF THE INVENTION
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a side perspective view of a putter in accordance
with the present invention;
[0019] FIG. 2 is a top perspective view of a putter head in
accordance with the present invention;
[0020] FIG. 3 is a front perspective view of a putter head in
accordance with the present invention;
[0021] FIG. 4 is a top view of a putter head in accordance with the
present invention;
[0022] FIG. 5 is a top sectional view of the club head;
[0023] FIG. 6 is a graph illustrating an Error Variability Reducing
profile for various Error Variability Reducing Inserts of the
present invention;
[0024] FIG. 7 is a front side view of an embodiment of a golf
putter with a configurable EVR putter head;
[0025] FIG. 8 is a rear side view of the golf putter of FIG. 7;
[0026] FIG. 9 is a rear side view of a head cavity within the golf
putter of FIG. 7;
[0027] FIG. 10 is a front perspective view of the head cavity
within the golf putter of FIG. 7;
[0028] FIG. 11 is a rear perspective view of the head cavity within
the golf putter of FIG. 7;
[0029] FIG. 12 is a top perspective view of an embodiment of an EVR
insert assembly;
[0030] FIG. 13 is a top section view of the EVR insert assembly of
FIG. 12;
[0031] FIG. 14 is a top section view of a configurable EVR putter
head;
[0032] FIG. 15 is a top section view of an embodiment of an EVR
insert assembly;
[0033] FIG. 16 is a rear view of an embodiment of a backplate;
[0034] FIG. 17 is a rear view of an embodiment of a backplate;
and
[0035] FIG. 18 is a rear view of an embodiment of a backplate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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 234a, 234b, 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 242a, 242b
extending into head body 212 such that the head bores 242a, 242b do
not extend to the front side 224. Head bores 242a, 242b can include
an internal thread or other suitable attachment means.
[0046] 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 256a, 256b. Projecting arms 256a, 256b
include arm flanges 257a, 257b and insert bores 258a, 258b.
Projecting arms 256a, 256b and plate surface 254 are dimensioned to
snugly accommodate the striking layer 244 and the flange surface
252 of striking layer 244. Projecting arms 256a, 256b are
dimensioned such that the distance between insert bores 258a, 258b
corresponds to the distance between head bores 242a, 242b.
[0047] 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 257a, 257b are in contact with front cavity surface 240
such that head bore 242a is aligned with insert bore 258a and head
bore 242b is aligned with insert bore 258b. Finally, a pair of
fasteners 260a, 260b, such as a pair of screws, is directed into
the insert bores 258a, 258b and subsequently into head bores 242a,
242b to operably couple the EVR insert assembly 214 and the head
body 212.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
1TABLE 1 Column A Non- Column B Column C Proportionally
Proportionally Force-Adjusted Putt Damped Putts Damped Putts Damped
Putts 1 8 ft 5.6 ft 9.2 ft 2 9 ft 6.3 ft 9.9 ft 3 10 ft 7.0 ft 10.6
ft 4 10 ft 7.0 ft 10.6 ft 5 11 ft 7.7 ft 11.3 ft 6 13 ft 9.1 ft
12.7 ft 7 14 ft 9.8 ft 13.4 ft 8 14 ft 9.8 ft 13.4 ft 9 15 ft 10.5
ft 14.1 ft 10 16 ft 11.2 ft 14.8 ft Average 12 ft 8.4 ft 12.0 ft
Range 8 ft 5.6 ft 5.6 ft Standard Deviation 2.74 ft 1.92 ft 1.92
ft
[0053] Quantitatively, putting accuracy with an EVR putter improves
by .rho., on average, over putting accuracy with a comparable
non-EVR putter where accuracy is measured by standard deviation,
where S.sub.c=1-.rho. (S.sub.A).
[0054] S.sub.C: Standard deviation of putts with a proportional
damping putter
[0055] S.sub.A: Standard deviation of putts with a comparably
non-EVR putter
[0056] .rho.: The damping proportion.
[0057] 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.
[0058] 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:
[0059] Putter 1: A putter similar to putter 10 including an insert
consisting of a UHMW polyethylene striking surface meeting the USGA
hardness standard.
[0060] 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.).
[0061] 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.
[0062] 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.).
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
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