Disclosed is an improved putter whose head and grip weighs 320 to 360 grams and 100 to 260 grams, respectively. The total weight of the head and grip ranges from 445 to 585 grams. The grip-and-head weighting according to the present invention has the effect of improving the rolling of the ball to extend the rolling-and-running distance of the ball; and improving the stableness and directionality of the swing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a golf club, particularly a putter whose 
grip is so weighted that the most effective stroke may be assured. 
2. Description of Related Art 
A putter comprises a shaft having a head and a grip fixed to its opposite 
ends. The weights of these components of a standard putter using a steel 
shaft are as for instance, follows: 
______________________________________ 
head weight W.sub.H = 320 g 
grip weight W.sub.G = 65 g 
shaft weight W.sub.S = 115 g 
total weight W.sub.T = 500 g 
______________________________________ 
If use is made of a carbon shaft, FRP shaft or any other light-weight shaft 
weighing 30 to 80 grams, the total weight W.sub.T ranges from 415 to 465 
grams. 
As is well known, it is important in putting that a golf ball can be 
controlled to rotate and run accurately in the distance and the direction. 
To increase the rotating-and-running distance it is necessary to give an 
increased amount of kinetic energy to the ball at the time of hitting 
whereas to control the rotating-and-running direction with accuracy it is 
necessary to give a stable swing to the putter club with the front part or 
face of the head facing perpendicular to the rotating-and-running 
direction. In respect of this the club should be designed so as to permit 
players to swing it with ease. 
In an attempt to improve the rolling of balls, the head of a putter is 
designed so as to be heavier than the above standard head weight W.sub.H. 
A somewhat heavier head is used initially, or an adjustment is done by 
attaching a lead weight to the head of a putter later. The kinetic energy 
which is given to a golf ball at the time of hitting is given by the 
following equation: 
EQU E=1/2MV.sup.2 =1/2W.sub.H /g V.sup.2 ( 1) 
wherein 
M: mass of the head of a putter; 
V: velocity of the head; and 
W.sub.H : weight of the head. 
As is apparent from the equation, the kinetic energy increases with the 
weight of the head W.sub.H, and the increase of the kinetic energy will 
improve the rolling of balls. On the other hand the club cannot be swung 
with ease, and therefore, the stable stroke and the correct directionality 
are hardly attainable. 
SUMMARY OF THE INVENTION 
In view of the above one object of the present invention is to provide a 
putter which improves the rolling-and-running of balls and at the same 
time, the stableness and directionality of the stroke. 
To attain this object according to the present invention, a putter golf 
club comprising a shaft having a head and a grip fixed at its opposite 
ends is characterized in that: said head weighs 320 to 360 grams; said 
grip weighs 100 to 260 grams; and the total weight of said head and grip 
ranges from 445 to 585 grams. 
The center of gravity of said grip may be located 100 to 150 millimeters 
apart from the end of said grip. 
The grip weighing 100 to 260 grams, is heavier than the grip of a 
conventional club, which grip weighs 65 grams. Accordingly the center of 
gravity of the club gets closer to the end of the grip with the result 
that the club can be swung more easily than the conventional club, 
increasing the speed of the head in swinging and accordingly increasing 
the kinetic energy of the golf ball to improve the rolling of the ball. 
The increased easiness with which the club can be swung has the effect of 
improving the stableness and directionality of the stroke. 
If the center of gravity of the grip is 100 to 150 millimeters apart from 
the end of the grip, the center of gravity of the grip is positioned at 
the middle of the grip, thus putting the center of gravity of the grip in 
both hands when the grip is held in hands. This permits the grip and hands 
to combine together so as to form a whole, thus facilitating the swinging 
of the club. 
Other objects and advantages of the present invention will be understood 
from the following description of grip-weighted putters according to 
preferred embodiments of the present invention referring accompanied 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a weight-distribution diagram which shows the domain (hatched 
area) of possible combinations (W.sub.H +W.sub.G) of head weight W.sub.H 
and grip weight W.sub.G in designing putters according to the present 
invention. Any putters whose head-and-grip weights fall within the hatched 
area are found to have the effect of improving the rolling of golf balls 
and of increasing the stableness of the stroke and improving the 
directionality of the stroke. This finding is based on the following 
theoretical analysis and experimental data. 
The following physical quantities are selected for determining conditions 
in which strokes are given to putters. 
(1) The amount of energy E to be given to a golf ball: 
EQU E=1/2M.sub.H V.sub.H.sup.2 =1/2W.sub.H /g.multidot.V.sub.H.sup.2(1) 
where 
M.sub.H : mass of the head of a putter; 
V.sub.H : velocity of the head; 
W.sub.H : weight of the head; and 
g: acceleration of gravity. 
(2) The speed of the head: 
As seen from FIG. 2, a putter club 5 comprises a shaft 3 having a head 2 
and a grip 1 fixed to its opposite ends. The center point of swing O is 
located on the line extending upwards from the end C of the grip 1; the 
center of gravity of the putter club 5 is indicated at G; and the center 
of gravity of the head 2 is indicated at H. The end C of the grip 1 is 
connected to the center point of swing O to form a pendulum. When the club 
is swung about its center point O, the speed V.sub.H of the head 2 is 
given by the following equation: 
EQU I.sub.O .theta.=-L'.multidot.W.sub.T .multidot.sin .theta. (1) 
where 
I.sub.O : inertia moment of the club 5 about the center point of swing O; 
L': distance from O to G; 
W.sub.T : total weight of the club; 
.theta.: swing angle of the pendulum; and 
.theta.: angular acceleration of pendulum swing. 
The general solution of Equation (2) is given by: 
##EQU1## 
where .omega.=.theta.: angular acceleration of pendulum swing; and 
.theta..sub.S : initial angle formed between the vertical line and the 
starting line of the pendulum. 
The head speed V.sub.H is given by: 
##EQU2## 
where L: distance from O to H; and 
L'=OG=OC+CG=L.sub.O +L.sub.G 
The following values which are presumably actual values for an ordinary 
putting, are added to Equation (4) as substitutes for the corresponding 
variables. 
EQU L.sub.O =20 cm 
EQU .theta.=0.degree. 
EQU .theta..sub.S =40.degree. 
EQU L'=L.sub.O +L.sub.G =20 cm+L.sub.G 
EQU L=l (C to H length)+L.sub.O =34 inch+20 cm=106.36 cm 
##EQU3## 
The units of these variables are: 
W.sub.T : (kg.multidot.f) 
L.sub.G : (cm) 
I.sub.O : (kg.multidot.cm.sup.2) 
Given values of these variables are added to substitute for corresponding 
variables in Equation (5) to determine head speeds V.sub.H. I.sub.O is 
determined by: 
##EQU4## 
where I.sub.G : inertia moment about the center of gravity of the putter; 
and 
M.sub.T : total mass of the putter. 
The inertia moment I.sub.C about the grip end C is given by: 
EQU I.sub.C =I.sub.G +W.sub.T /g L.sub.G.sup.2 (7) 
The easiness for a player to swing a putter, i.e. the feeling of swinging 
will be greatly influenced by this inertia moment I.sub.C. 
A conventional putter (referred to as "MODEL A") and putters whose heads 
and grips are weighted according to the present invention (referred to as 
models "B", "C", "D" and "E") were prepared, and the head speeds V.sub.H, 
kinetic energies and inertia moments I.sub.C of these putter models were 
determined according to the above equations. The results are given in the 
following Tables 1 and 2. 
TABLE 1 
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Model No. 
W.sub.H (g) 
W.sub.G (g) 
W.sub.S (g) 
W.sub.T (g) 
I.sub.G (kg .multidot. cm.sup.2) 
L.sub.G (mm) 
I.sub.C kg .multidot. cm.sup.2 
__________________________________________________________________________ 
A 320 65 115 500 478.7 649.9 
2590.6 
B 320 125 115 560 601.1 605.9 
2656.9 
(A + 60) (A + 60) 
C 320 265 115 700 886.9 503.2 
2659.4 
(A + 200 (A + 200 
D 360 100 115 575 569.5 639.3 
2919.6 
(A + 40) 
(A + 35) (A + 75) 
E 360 225 115 700 843.8 550.9 
2968.2 
(A + 40) 
(A + 160 (A + 200 
__________________________________________________________________________ 
A: conventional standard putter club 
B.about.E: A + a (weight added) 
W.sub.H : head weight 
W.sub.G : grip weight 
W.sub.T : total weight of putter club 
I.sub.G : inertia moment about the center of gravity of the club 
L.sub.G : distance from grip end to center of gravity of the club 
I.sub.C : inertia moment about the grip end 
W.sub.S : shaft weight 
TABLE 2 
______________________________________ 
Model V.sub.H V.sub.H ratio 
E E ratio 
No. (cm/S) to A (kg .multidot. cm.sup.2 /S.sup.2) 
to A 
______________________________________ 
A 232 100% 8612 100% 
B 235 101.3 8836 102.6 
C 242 104.3 9370 108.8 
D 233 100.4 9772 113.5 
E 239 103.0 10280 119.4 
______________________________________ 
V.sub.H : head speed 
E: kinetic energy 
As regards models A to E, the graphs of FIGS. 3, 4 and 5 show how the head 
speed ratio (V.sub.H of each of models B to E/V.sub.H of model A) varies 
with grip weight; how the energy increasing ratio (energy E each of models 
B to E/energy E of model A) varies with grip weight; and how the inertia 
moment I.sub.C varies with grip weight. As seen from FIG. 4, the energy E 
increases with the increase of the grip weight W.sub.G, and the energy E 
increases greatly when extra weight is added to the head. Also, as seen 
from FIG. 5, the inertia moment I.sub.C is independent from the increase 
or decrease of the grip weight W.sub.G, but the inertia moment is greatly 
influenced by increasing or decreasing the head weight W.sub.H. 
FIG. 6 shows data pertaining to numerous combinations of different grip 
weights and head weights, which are provided by adding extra weights of 50 
g, 62.5 g, 75 g, 87.5 g, 100 g, 150 g and 200 g to the grip weight of 
model A and by adding extra weights of 12.5 g, 25 g, 37.5 g and so forth 
to the head weight of model A. The shaft of model A was made of steel, and 
it weighed 115 g. In FIG. 6 points A, B, C, D and E indicate the head 
weights W.sub.H and grip weights W.sub.G of model A to E given in Table 1. 
Putters according to the present invention fall within the domain defined 
by thick line connecting points B, D, E and C. Point A remains out of the 
specific domain, clearly indicating in the diagram, the difference between 
the conventional putter A and putters according to the present invention. 
The graph of the V.sub.H ratio in FIG. 6 shows that the increase of the 
grip weight W.sub.G is more effective to increase the head speed V.sub.H 
than the increase of the head weight W.sub.H. Also, it shows that the 
increase of the head weight W.sub.H is more effective to increase the 
energy E than the increase of the grip weight W.sub.G. The increase of the 
head weight W.sub.H, however, will permit a great increase of inertia 
moment I.sub.C with the result that the stableness and directionality of 
swinging is lowered. A compromise between the grip weight and the head 
weight of a putter according to the present invention was made in 
consideration of these factors, and most appropriate shares between the 
grip weight W.sub.G and the head weight W.sub.H are found in the domains 
defined by thick lines in FIGS. 1 and 6. 
In determining such domains of most appropriate grip-and-head weight shares 
tens of golf players including professional players tried a variety of 
grip-weighted putters according to the present invention, and their 
evaluations of these grip-weighted putters were collected. 
Specifically four grip-weighted putters were tested, and their grips 
weighed 115 g, 165 g, 215 g and 265 g. These are heavier than the grip of 
the conventional standard putter model A (65 g) by extra weight of 50 g, 
100 g, 150 g and 200 g respectively. The weighting distribution along the 
grip length was so determined that the center of gravity of each grip was 
100 to 150 millimeters apart from the grip end C, that is, around the 
midpoint of the grip length. 
Almost all golf players (94%) said that the grip-weighted putters were easy 
to swing. One half or more of the golf players made a favorable comment on 
the putters whose grips had extra weight of 100 g and 150 g. They said 
that the putters whose grips had extra weights of 50 g were hardly 
distinguishable from the conventional standard putter, and that the 
putters whose grips had extra weight of 200 g were too heavy, and they are 
anxious about a long- distance putting. 
From this it is apparent that an appropriate grip-weighting has the effect 
of stabilizing the stroke and facilitating the swing of the club. The most 
appropriate grip-weighting cannot be determined to be one particular 
physical quantity. As a matter of fact, the most appropriate 
grip-weighting depends on individuals, specifically their statues, weights 
and other physical factors, such as their putting postures. FIGS. 7a, 7b 
and 7c show three different putting postures, which are hereinafter called 
"shoulder type", "arm type" and "tap type" respectively. The shoulder type 
of putting is very close to the pendulum swinging described above, 
permitting the head of the club to swing large amplitude, compared with 
the grip of the club. The majority of players of this type said, "The head 
runs, and the ball rolls well." In the arm type of putting the hands and 
the head move as a whole, and therefore, there is only a small difference 
between the head move and the grip move. The majority of players of this 
type did not feel that: the head runs, and the ball rolls well. Finally, 
the tap type of putting permits only little move of the grip, and 
therefore, the grip-weighting will cause little or no advantageous effect. 
In general, there are few golf players of perfect shoulder type or perfect 
arm type. Most golf players take the posture intermediate between these 
putting types. Few people take the posture of tap type. 
FIGS. 8a and 8b show the test results. A variety of evaluations appear to 
be attributable to individual difference, but putters whose grips have 
extra weight of 100 g or 150 g won popularity. 
The above description pertains standard steel-shaft putters (shaft weighing 
115 g) which were modified by weighting their grips and heads as described 
above. It, however, should by noted that Equations (1) to (6) can hold for 
putters using carbon black or any other light-weight shaft and that the 
same advantage as the above described examples can be provided by 
weighting their grips according to the present invention. 
As may be understood from the above, the weighting of the grip and head of 
a putter according to the present invention has the effects of: 
(1) increasing the head speed in the stroke and accordingly increasing the 
kinetic energy of the golf ball; improving the rolling of the ball; and 
extending the rolling-and running distance; 
(2) shortening the distance from the grip end to the center of gravity of 
the club to facilitate the swing, and improve the stableness and 
directionality of the swing; and 
(3) positioning the center of gravity of the grip at the intermediate point 
of the grip length, thereby permitting both hands and the grip to be 
combined into an integral form, and accordingly facilitating the swing.