U.S. patent number RE34,420 [Application Number 07/616,649] was granted by the patent office on 1993-10-26 for sports racquet.
Invention is credited to James P. Darling.
United States Patent |
RE34,420 |
Darling |
October 26, 1993 |
Sports racquet
Abstract
An improved sports racquet is provided having elements placed
between the outer edge of the frame and the strings. The elements
prevent the strings from touching the outer edge of the frame and
rotate in response to a force applied in a direction generally
perpendicular to the strings, thereby expanding the sweet spot,
providing improved playability of the racquet, and significantly
reducing the .[.fibration.]. .Iadd.vibration .Iaddend.that is
transferred to the player's arm. The elements are preferably
spherical in shape and may be comprised of various materials,
including acetal, plastic and metal. The elements preferably rest
in receptacles in the racquet frame, which may be integral with the
frame or separate pieces, such as sleeves or grommets, that are
connected to the frame. The receptacles are preferably designed to
have a surface with substantially the same curvature as the bottom
surface of the elements.
Inventors: |
Darling; James P. (Seal Beach,
CA) |
Family
ID: |
27087822 |
Appl.
No.: |
07/616,649 |
Filed: |
November 21, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
876982 |
Jun 19, 1986 |
04786055 |
Nov 22, 1988 |
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Current U.S.
Class: |
473/522 |
Current CPC
Class: |
A63B
49/028 (20151001); A63B 60/54 (20151001); A63B
49/025 (20151001) |
Current International
Class: |
A63B
49/00 (20060101); A63B 59/00 (20060101); A63B
051/10 () |
Field of
Search: |
;273/73R,73C,73D,73E,73G,73H |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Millin V.
Assistant Examiner: Stoll; William E.
Attorney, Agent or Firm: Poms, Smith, Lande & Rose
Claims
I claim:
1. A sports racquet comprising:
(a) a handle
(b) a frame attached to or integral with said handle, said frame
having an inner perimeter and an outer perimeter, and having a
plurality of spaced frame passages disposed in the frame and
extending between the inner perimeter and the outer perimeter
thereof for receiving strings;
(c) strings disposed within said frame in a generally
cross-networked array to form a playing surface; said strings
extending through said frame passages; and
(d) a plurality of elements contacting and resting on the outer
perimeter of said frame, the surface of said elements that contacts
the outer perimeter of said frame being convex, such that the
location of each element with respect to the frame is fixed, each
element having a passage extending through said element for
receiving said strings, .Iadd.each element having a bottom portion
on its outer surface that is closest to the center of said playing
surface and a top portion on its outer surface that is further from
the center of said playing surface, each element having a
rotational axis that is generally parallel to said playing surface
and generally orthogonal to the string received in said element,
.Iaddend.each of said elements being aligned with one of said frame
passages such that each of said strings passes through said frame
passage and said element passage so that said strings are prevented
from contacting the frame, said elements being positioned such
that.Iadd., when a sufficient force is applied to said playing
surface in a direction generally perpendicular to said playing
surface, .Iaddend.the axis of said element passage moves, but the
location of said element with respect to the frame does not change,
.[.when a sufficient force is applied to said playing surface in a
direction generally perpendicular to said playing surface.].
.Iadd.the top portion of said element rotating about the rotational
axis of said element toward a direction opposite to the direction
of application of the force.Iaddend..
2. The sports racquet of claim 1 wherein said elements have a
substantially spherical shape.
3. The sports racquet of claim 2 wherein said elements are about
one eighth inch to about one half inch in diameter.
4. The sports racquet of claim 1 wherein said elements have a
substantially hemispherical shape.
5. The sports racquet of claim 4 wherein the spherical portion of
said elements has a radius of about one sixteenth inch to about one
quarter inch.
6. The sports racquet of claim 1 wherein said elements have a
substantially .[.elliptical.]. .Iadd.ellipsoidal .Iaddend.shape,
each of said elements being aligned such that its major axis
extends along the outer perimeter of said frame along a line that
is parallel to a line tangent to the outer perimeter of said frame
at the point of contact between the element and the frame
.Iadd.generally parallel to said playing surface and generally
orthogonal to the string received in said element.Iaddend..
7. The sports racquet of claim 1 wherein said elements have a
hardness ranging from about R-85 to about R-120 on the Rockwell
hardness scale.
8. The sports racquet of claim 1 wherein said elements are made of
plastics or metals or a composite of both.
9. The sports racquet of claim 1 wherein the passage through said
element is linear.
10. The sports racquet of claim 1 wherein the outer perimeter of
the frame has a plurality of concave surfaces located at the outer
end of each frame passage to matingly receive the convex surface of
each element.
11. The sports racquet of claim 10 wherein a sleeve extends from
said element toward the inner perimeter of said frame.
12. The sports racquet of claim 1 wherein the portion of said frame
passages on the inside perimeter of said frame are of sufficient
diameter such that said strings do not contact the frame when said
sufficient force is applied to said playing surface.
13. A sports racquet comprising:
(a) a handle
(b) a frame attached to or integral with said handle, said frame
having an inner perimeter and an outer perimeter, and having a
plurality of spaced frame passages disposed in the frame and
extending between the inner perimeter and the outer perimeter
thereof for receiving strings;
(c) strings disposed within said frame in a generally
cross-networked array to form a playing surface; said strings
extending through said frame passages; and
(d) a plurality of elements contacting and resting on the outer
perimeter of said frame, such that the location of each element
with respect to the frame is fixed, each element having a passage
extending through said element for receiving said strings,
.Iadd.each element having a bottom portion on its outer surface
that is closet to the center of said playing surface and a top
portion on its outer surface that is further from the center of
said playing surface, each element having a rotational axis that is
generally parallel to said playing surface and generally orthogonal
to the string received in said element, .Iaddend.each of said
elements being aligned with one of said frame passages such that
each of said strings passes through said frame passage and said
element passage so that said strings are prevented from contacting
the frame, said elements having a cylinder integral therewith
extending from said elements, said cylinder having an internal
passage along its major axis that is aligned with said element
passage, said elements being positioned such that, .Iadd.when a
sufficient force is applied to said playing surface in a direction
generally perpendicular to said playing surface, .Iaddend.the axis
of said element passage moves, but the location of said element
with respect to the frame does not change, .[.when a sufficient
force is applied to said playing surface in a direction generally
perpendicular to said playing surface.]. .Iadd.the top portion of
said element rotating about the rotational axis of said element
toward a direction opposite to the direction of application of the
force.Iaddend..
14. A sports racquet comprising:
(a) a handle;
(b) a frame attached to or integral with said handle, ssaid frame
having an inner perimeter and an outer perimeter, and having a
plurality of spaced frame passages disposed in the frame and
extending between the inner perimeter and the outer perimeter
thereof for receiving strings;
(c) strings disposed within said frame in a generally
cross-networked array to form a playing surface; said strings
extending through said frame passages; and
(d) a plurality of elements contacting and resting on the outer
perimeter of said frame such that the location of each element with
respect to the frame is fixed, each element having a non-linear
passage extending through said element for receiving said strings,
.Iadd.each element having a bottom portion on its outer surface
that is closet to the center of said playing surface and a top
portion on its outer surface that is further from the center of
said playing surface, each element having a rotational axis that is
generally parallel to said playing surface and generally orthogonal
to the string received in said element, .Iaddend.each of said
elements being aligned with one of said frame passages such that
each of said strings passes through said frame passage and said
element passage so that said strings are prevented from contacting
the frame, said elements being positioned such that, .Iadd.when a
sufficient force is applied to said playing surface in a direction
generally perpendicular to said playing surface, .Iaddend.the axis
of said element passage moves, but the location of said element
with respect to the frame does not change, .[.when a sufficient
force is applied to said playing surface in a direction generally
perpendicular to said playing surface.]. .Iadd.the top portion of
said elements rotating about the rotational axis of said element
toward a direction opposite to the direction of application of the
force.Iaddend..
15. A sports racquet comprising:
(a) a handle
(b) a frame attached to or integral with said handle, said frame
having an inner perimeter and an outer perimeter, and having a
plurality of spaced frame passages disposed in the frame and
extending between the inner perimeter and the outer perimeter
thereof for receiving strings;
(c) strings disposed within said frame in a generally
cross-networked array to form a playing surface; said strings
extending through said frame passages; and
(d) a plurality of elements contacting and resting on the outer
perimeter of said frame such that the location of each element with
respect to the frame is fixed, each element having a passage
extending through said element for receiving said strings,
.Iadd.each element having a bottom portion on its outer surface
that is closet to the center of said playing surface and a top
portion on its outer surface that is further from the center of
said playing surface, each element having a rotational axis that is
generally parallel to said playing surface and generally orthogonal
to the string received in said element, .Iaddend.each of said
elements being aligned with one of said frame passages such that
each of said strings passes through said frame passage and said
element passage so that said strings are prevented from contacting
the frame, each of said spaced passages being on the same axis as
the string that passes through that particular passage, said
elements being positioned such that .Iadd.when a sufficient force
is applied to said playing surface in a direction generally
perpendicular to said playing surface, .Iaddend.the axis of said
element passage moves, but the location of said element with
respect to the frame does not change, .[.when a sufficient force is
applied to said playing surface in a direction generally
perpendicular to said playing surface.]. .Iadd.the top portion of
said element rotating about the rotational axis of said element
toward a direction opposite to the direction of application of the
force.Iaddend..
16. A sports racquet comprising:
(a) a handle
(b) a frame attached to or integral with said handle, said frame
having an inner perimeter and an outer perimeter, and having a
plurality of spaced frame passages disposed in the frame and
extending between the inner perimeter and the outer perimeter
thereof for receiving strings and having a receptacle portion;
(c) strings disposed within said frame in a generally
cross-networked array to form a playing surface, said strings
extending through said frame passages; and
(d) a plurality of spherical elements contacting and resting on the
outer perimeter of said frame such that the location of each
element with respect to the frame is fixed, each element having a
passage extending through said element for receiving said strings
each of said elements contacting the receptacle portion of said
frame passages such that each of said strings passes through said
frame passage and said element passage, so that said strings are
prevented from contacting said frame, said elements being
positioned such that said elements rotate when a sufficient force
is applied to said playing surface in a direction generally
perpendicular to said playing surface. .Iadd.
17. In a sports racquet comprising a handle; a frame attached to or
integral with the handle; the frame having an inner perimeter and
an outer perimeter, and having a plurality of spaced frame passages
disposed in the frame and extending between the inner perimeter and
the outer perimeter for receiving strings; strings disposed within
the frame in a generally cross-networked array to form a playing
surface; the strings extending through the frame passages; wherein
the improvement comprises the provision of:
(a) a plurality of elements contacting and resting on the outer
perimeter of the frame;
(b) receptacle means in the outer perimeter of the frame for fixing
the location of each element with respect to the frame;
(c) each element having passageway means extending through the
element for receiving a portion of the strings, each element having
a bottom portion on its outer surface that is closest to the center
of said playing surface and a top portion on its outer surface that
is further from the center of said playing surface, each element
having a rotational axis that is generally parallel to said playing
surface and generally orthogonal to the string received in said
element;
(d) each element having alignment means for aligning the element
with the frame passages such that each of the strings passes
through the frame passage and the passageway to prevent the strings
from contacting the frame;
(e) the receptacle means positioning the elements such that when a
sufficient force is applied to the playing surface in a direction
generally perpendicular to the playing surface, the top portion of
said element rotating about the rotational axis of said element
toward a direction opposite to the direction of application of the
force. .Iaddend. .Iadd.
18. The improved sports racquet of claim 17 at least a first
portion of each element has a curvilinear shape. .Iaddend.
.Iadd.19. In a frame for a sports racquet the frame having an inner
perimeter and an outer perimeter, and having a plurality of spaced
frame passages disposed in the frame and extending between the
inner perimeter and the outer perimeter; strings disposed within
the frame in a generally cross-networked array to form a playing
surface; the strings extending through the frame passages; wherein
the improvement comprises the provision of:
a plurality of elements contacting and resting on the outer
perimeter of the frame, each element having at least one element
passage extending through the element for receiving the strings,
each element passage having an axis, each of the elements having at
least one bearing portion, which is aligned with one of the frame
passages such that each of the strings passes through the frame
passage and the element passage so that the strings are prevented
from contacting the frame, receptacles in the outer perimeter for
receiving the elements, the receptacles having curvilinear surfaces
corresponding to the shape of a seating portion for receiving the
bearing portion, each element having a bottom portion on its outer
surface that is closest to the center of said playing surface and a
top portion on its outer surface that is further from the center of
said playing surface, each element having a rotational axis that is
generally parallel to said playing surface and generally orthogonal
to the string received in said element, the elements being
positioned such that, when a sufficient force is applied to the
playing surface in a direction generally perpendicular to the
playing surface, the axis of the element passage moves, but the
location of the element with respect to the frame does not change,
the top portion of said element rotating about the rotational axis
of said element toward a direction opposite to the direction of
application of the force. .Iaddend. .Iadd.20. In a frame for a
sports racquet the frame having an inner perimeter and an outer
perimeter, and having a plurality of spaced frame passages disposed
in the frame and extending between the inner perimeter and the
outer perimeter; strings disposed within the frame in a generally
cross-networked array to form a playing surface; the strings
extending through the frame passages; wherein the improvement
comprises the provision of:
a plurality of elements contacting and resting on the outer
perimeter of the frame, each element having at least one element
passage extending through the element for receiving the strings,
each element passage having an axis; each of the elements having at
least one bearing portion, which is aligned with one of the frame
passages such that each of the strings passes through the frame
passage and the element passage so that the strings are prevented
from contacting the frame, receptacles in the outer perimeter for
receiving the elements, the receptacles having curvilinear seating
surfaces for receiving a bearing portion, the elements being
positioned such that the axis of the element passage moves when a
sufficient force is applied to the playing surface in a direction
generally perpendicular to the playing surface. .Iaddend. .Iadd.21.
The sports racquet of claim 1 wherein the outer perimeter of said
frame has a plurality of curvilinear, concave receptacles for
receiving the convex element, each element having an outer surface
and each receptacle having an inner surface contacting the
element's outer surface, the element's outer surface sliding along
the receptacle's inner surface when the axis of said element
passage moves. .Iaddend. .Iadd.22. The sports racquet of claim 10
wherein the convex surface of each element extends along the entire
surface of each element facing the outer perimeter of said frame,
said concave surfaces at the outer end of each frame passage
extending substantially around the concave surface. .Iaddend.
.Iadd.23. In a sports racquet comprising a handle; a frame attached
to or integral with the handle; the frame having an inner perimeter
and an outer perimeter, and having a plurality of spaced frame
passages disposed in the frame and extending between the inner
perimeter and the outer perimeter for receiving strings; strings
disposed within the frame in a generally cross-networked array to
form a playing surface; the strings extending through the frame
passages; wherein the improvement comprises the provision of:
(a) a plurality of elements contacting and resting on the outer
perimeter of the frame;
(b) at least one receptacle in the outer perimeter of the
frame;
)c) each element having at least one passageway extending through
the element for receiving a portion of the strings;
(d) each element having a bottom portion on its outer surface that
is closest to the center of said playing surface and a top portion
on its outer surface that is further from the center of said
playing surface, each element having a rotational axis that is
generally parallel to said playing surface and generally orthogonal
to the string received in said element;
(e) each element being aligned with the frame passages such that
each of the strings passes through the frame passage and the
passageway to prevent the strings from contacting the frame;
(f) the receptacle positioning the elements such that when a
sufficient force is applied to the playing surface in a direction
generally perpendicular to the playing surface, the top portion of
said element rotating about the rotational axis of said element
toward a direction opposite to the direction of application of the
force. .Iaddend.
Description
.Iadd.The application is a reissue of 06/876982 filed Jun. 19, 1986
patent No. 4,786,055. .Iaddend.
BACKGROUND OF THE INVENTION
Racquet sports such as tennis, racquetball and squash have become
extremely popular throughout the world over the past few decades.
All three of these sports are played with a racquet generally
having a handle, a frame and strings interwoven through the frame
to form a playing surface. The players direct a ball, different for
each sport, to a desired location by striking the ball with the
playing surface of the racquet formed by the strings.
The power and control of a given racquet are dependent on many
factors, including the size, weight and shape of the racquet, the
materials from which the racquet and strings are made, and the
tension of the strings in the racquet frame. It is naturally
desirable to optimize both power and control, but one problem with
racquet development is that racquet and string configurations which
optimize power often sacrifice control, and vice-versa.
Generally speaking, there is a particular area on every racquet,
usually near and surrounding the center, in which it is desirable
to hit the ball for maximum power and control. This area is known
as the "sweet spot." The location and shape of the sweet spot
varies with racquet shape and design, but is desirable on all
racquets to have a sweet spot that is as large as possible.
Another problem with sports racquets generally is that the force of
the ball striking the strings causes a vibration in the racquet
frame, particularly when the ball strikes the playing surface
outside of the sweet spot. This vibration is transferred from the
racquet frame to the arm of the person using the racquet. Extended
play often causes serious health problems, particularly to the
elbow of the playing arm because of the vibration just described.
Among tennis players, this condition is commonly known as "tennis
elbow."
Various attempts have been made to both improve playability of
sports racquets and lessen the vibration that is transferred to the
player's arm upon contact of the racquet with the ball,
particularly when the ball strikes outside of the sweet spot. For
example, materials have been placed between the outer edge of the
racquet frame and the strings to dampen vibration. These
arrangements are not particularly effective, however, because these
materials are in a fixed position relative to the frame and the
strings when the racquet is being used. Thus, vibration is
transferred directly from the strings, through the intermediate
materials, to the racquet frame, and then to the player's arm.
Designs have also been developed that permit the tension of each
string to be adjusted individually, purportedly allowing the
playability of a racquet to be tailored to each player. This
design, however, has the disadvantage of being cumbersome to
implement, since the precise effect of adjusting each string is
difficult to determine, and because each string must be constantly
adjusted to maintain the desired tension profile. Additionally,
racquet stringers are adverse to using many individual strings to
string a racquet, since the usual procedure is to weave a single
string through the racquet frame to form the playing surface.
What is needed, therefore, .[.an.]. .Iadd.is .Iaddend.an
inexpensive and simple design for a sports racquet with an expanded
sweet spot that provides improved power and control and lessens the
vibration to the player's arm caused by impact of the strings with
the ball. The racquet of the present invention satisfies these
needs and provides other related advantages.
SUMMARY OF THE INVENTION
The present invention resides in an improved sports racquet having
elements spaced between the strings and the outer edge of the
racquet frame. These elements isolate the strings from the frame
and move in response to a force applied to the strings from a
generally perpendicular direction. The improved racquet exhibits
substantially improved playability, primarily because of an
increase in the area of the sweet spot, and significantly reduces
the amount of vibration from impact of the ball on the strings that
is transferred to the player's arm. The elements of the present
invention can be used with any sports racquet having strings,
including but not limited to tennis, racquetball and squash, and
may either be placed on racquets before initial sale or added to
racquets already in the hands of the public.
More specifically, the sports racquet of the present invention is
of a conventional type having a handle and a generally circular or
oval frame attached thereto. A playing surface is formed in the
area within the frame by taking a single string and passing it
alternately through spaced passages running from the outer
perimeter to the inner perimeter of the frame. A plurality of
strings may also be used. For convenience, the playing surface will
be referred to as "the strings," irrespective of whether one string
or a plurality of strings forms the playing surface.
In a conventional racquet, the strings pass through a spaced
passage in the frame from the inside to the outside, and then back
through one of the immediately adjacent spaced passages from the
outside to the inside. Thus, the strings rest directly on the outer
perimeter of the frame between the adjacent spaced passages. In the
racquet of the present invention, elements having passages therein
are placed on the outer perimeter of the frame, having their
passages aligned with the respective passages in the frame. The
strings run through each spaced passage in the frame, through an
element, then through another element and back through the
frame.
The elements of the present invention are preferably spherical in
shape, but may be of any shape having a curvilinear surface in
contact with the racquet frame, such as .[.elliptical.].
.Iadd.ellipsoidal .Iaddend.or hemispherical. The elements fit into
correspondingly shaped receptacles in the frame and rotate within
those receptacles in response to a force applied to the playing
surface. The receptacles may be formed integrally into the frame,
or may be separate sleeves or a .[.continous.]. .Iadd.continuous
.Iaddend.grommet having a curvilinear surface therein for receiving
said elements. Preferably, the sleeves or grommets should be made
of materials having hardness properties similar to those of the
elements so that the separate receptacles and the elements will
wear evenly over time from the rotation of the elements within the
receptacles.
A sleeve may also extend inward from the element. Varying the
length of the sleeve changes the action on the strings by changing
the rotation of the elements, the striking force being the
same.
The elements and receptacles may be made of materials of varying
hardness, including but not limited to plastics, acetal or metal,
or a composite thereof. The passage running through each element
may be radial or curved, and may be drilled by conventional
means.
In the case of spherical elements, the elements may be from one
eighth inch to one half inch in diameter. Generally, the smaller
the element, the greater the rotation that will occur in response
to a given force applied to the playing surface.
When the racquet of the present invention is in use, the ball
strikes the playing surface and some of the elements rotate in
their receptacles, depending on the location in which the ball
strikes the playing surface. Without being limited to any
particular theory, it is surmised that the rotation of the elements
allows the strings to move further in response to a given force,
thereby providing greater power and control. Moreover, the elements
are believed to rotate to a greater degree as the location of the
application of the force moves closer to the edge of the frame,
thereby expanding the area of the sweet spot.
Additionally, the elements serve to isolate the strings from the
frame and, by rotating in response to a force striking the playing
surface, to dissipate the vibration caused by this force striking
the playing surface.
Other features and advantages of the present invention will become
apparent from the following detailed description, which, taken in
conjunction with the accompanying drawings, illustrates, by way of
example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of the sports racket of the present
invention.
FIG. 2 is a side view of the sports racquet of the present
invention.
FIG. 3 is an enlarged view taken along the line III--III of FIG.
1.
FIG. 4 is a sectional view taken along the line IV--IV of FIG.
3.
FIG. 5 is a sectional view taken along the line V--V of FIG. 3.
FIG. 6 is a sectional view taken along the line V--V of FIG. 3,
showing the position of a string and an element of the racquet of
the present invention after the playing surface is struck with a
ball.
FIG. 7 is a sectional view of an alternative embodiment of the
present invention showing an element with a non-radial passage.
FIG. 8 is a sectional view of an alternative embodiment of the
present invention showing a hemispherical element.
FIG. 9 is a sectional view of an alternative embodiment of the
present invention showing an .[.eliptical.]. .Iadd.ellipsoidal
.Iaddend.element.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is embodied in elements that are placed
between the strings and the frame of a conventional sports racquet.
The elements rotate in response to a force striking the playing
surface of the racquet, thereby increasing the area of the sweet
spot and thus improving playability of the racquet, as well as
dissipating the vibration caused by a ball striking the playing
surface. Moreover, the elements of the present invention are
inexpensive to produce and simple to install, providing an
inexpensive and easy way to improve the playability of any sports
racquet and lessen the vibration that is transferred to the
player's arm.
Referring now to the drawings, FIG. 1 shows a tennis racquet 10
having a frame 12 and a handle 14. The handle 14 is connected to
the frame 12 by means of a neck 16. Strings 18 are interwoven
transversely and longitudinally within frame 12, thereby creating
playing surface 20. The playing surface 20 may be comprised of one
string or a plurality of strings, but in both cases will be
referred to as "strings."
As shown in FIG. 2, the perimeter of frame 12 contains a plurality
of spaced passages 22 running from the outside perimeter of frame
12 to the inside perimeter of frame 12. As seen in FIGS. 3 and 4,
an element 24 rests in each spaced passage 22. Each element has a
radial passage 25. The strings 26 and 28 pass from the inner
perimeter of frame 12, through one of the passages 22, through
radial passage 25 in element 24, and then back through another
radial passage 25 in element 24, and on through the outer perimeter
of frame 12 through another passage 22 to the inner perimeter of
frame 22.
Passages 22 have curvilinear shaped receptacles 30 on the outer
perimeter of the frame into which elements 24 are correspondingly
fit. As shown in FIG. 4, the elements 24 are offset in receptacles
30 so that when there is tension on strings 26 and 28, tending to
pull elements 24 to the inner surface of apertures 22, the spacing
between the strings 26 and 28 will be even. This is desirable for
aesthetic purposes, but elements 24 need not necessarily be offset
in receptacles 30, since the sports racquet will function
satisfactorily even if the strings are unevenly spaced.
Preferably, passage 22 where it contacts the inner perimeter of the
frame is wide enough so that string 32 does not contact the inner
perimeter of the frame during play, as shown in FIGS. 5 and 6.
Additionally, it is preferable that each passage lie on the same
axis as the string that passes through that particular passage.
FIGS. 5 and 6 show the rotation of elements 24 in receptacles 30.
FIG. 5 shows element 24, through which string 32 passes, in a
resting position. In FIG. 6, a ball 34 has struck the playing
surface 20, including string 32, at a substantially right angle. As
string 32 moves in response to being struck by ball 34, element 24
rotates in receptacle 30, thereby permitting greater movement of
string 32. As seen in FIG. 6, the passage 25 in element 24 is on a
different axis after being struck by ball 34 than its stationary
axis as shown in FIG. 5.
Since receptacles 30 are curvilinear, elements 24 can be of varying
sizes for use with the same receptacle to vary the action on
strings 18 passing through elements 24. Elements 24 of varying size
will still have a spherical surface that will contact receptacles
30, thereby permitting rotation of elements 24. Moreover, varying
the size of elements 24 will alter the action on strings 18, as a
given force will produce different angles of rotation depending on
the size of elements 24.
FIG. 7 shows an alternative embodiment in which the passage 25 of
elements 24 is curved rather than radical and in which element 24
rests in a separate sleeve or grommet 38 with a formed receptacle
30, rather than resting in an integrally formed receptacle 30 in
the frame 12 as depicted in FIG. 4. With a curved passage 25, the
tension on string 36 running through passage 25 does not change the
natural position in which element 24 rests, unlike the elements 24
shown in FIG. 4, whose radial passages rest at an angle with
respect to strings 26 and 28 because of the tension on strings 26
and 28. Thus, in the embodiment shown in FIG. 7, there is no need
to offset elements 24 in grommet 38, and grommet 38 may be
symmetrically shaped, Additionally, sleeve 40 is integral to
element 24, and may be of varying length to provide for different
action on strings 18.
FIG. 8 shows another alternative embodiment in which element 42 is
hemi-spherical rather than spherical as are elements 24 in the
preferred embodiment shown in FIGS. 1-6. Similarly, FIG. 9 shows
another alternative embodiment in which element 44 is
.[.elliptical.]. .Iadd.ellipsoidal .Iaddend.. These alternative
embodiments are provided by means of illustration only, and the
invention is not to be limited to any particular shaped element.
Any shape of element capable of movement in response to a force
applied to the playing surface 20 is within the scope of the
present invention.
The elements of the present invention are preferably comprised of
plastic materials such as acetal, which is a generic name for
polyoxymethylene type acetal resin made by the polymerization of
formaldehyde. Such materials generally have a hardness ranging from
about R85 to R120 on the Rockwell hardness scale. The elements may
also be comprised of metals, or a composite of plastic and
metal.
The passages 25 in elements 24 may be formed by conventional
drilling means or injection .[.moulding.]. .Iadd.molding
.Iaddend.methods. Similarly, the racquet of the present invention
may be strung on a conventional stringing machine, the only
difference being that the strings are inserted through passages 25
in elements 24 during stringing. Thus, the elements of the present
invention may be included as original equipment on sports racquet,
or may be added to sports racquets in the hands of the public when
such racquets are restrung.
The foregoing description demonstrates that the sports racquet of
the present invention provides significant advantages over those
previously known in the art. The elements of the present invention
are inexpensive and simple to construct, yet when added to a
conventional sports racquet, they greatly increase playability of
the racquet and reduce the vibration that is transferred from the
racquet to the player's arm, particularly when a ball strikes the
racquet off-center.
It should be apparent to those skilled in the art that other sports
racquets might be constructed without departing from the spirit and
scope of the present invention. Thus, the foregoing description is
meant for illustrative purposes only. The present invention is not
intended to be limited in any way, except as by the appended
claims.
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