Note: Descriptions are shown in the official language in which they were submitted.
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BADMINTON RACKET
BACKGROUND OF THE INVENTION
Field Of The Invention
:
This invention relates to badminton rackets, and, more
particularly, to a badminton racket which is lighter than prior
badmin~on rackets and which has a balance point or center of
gravity closer to the head end of the racket than to the handle
end.
Description Of The Prior Art
Badminton rackets conventionally have a length of about
26 inches and a weight of about 100 grams. The balance point or
center of gravity of those rackets li2~ closer to the handle end
of the racket than the head end. Accordingly, the prior
badminton rackets are "head light." They typically include lead
or other weight in the handle to increase the weight of the
racket and to produce the "head light" characteristic.
Representative competitive badminton rackets have the
following physical properties:
Weight Length . Balance Iend
(Gram~l ~Lrçhç~l ~Inches) loz. in.2L
g5 to 115 . 25.98 to 26.~3 11.34 to 12.60 7~7 to 826
"Balance" is the distance of the balance point or center of
gravity from the handle end of the racket. "Iend" is the momenk
of inertia about an axis at the end of the handle which extends
perpendicularly to the handle and is a measure of the ability of
the racket to resist rotation about the axis.
Frolow Reissue U.S. Patent No. 31,419 describes a
tennis racket which weighs less than conventional tennis
rackets. Weight, removed from the handle end and added to th~
head end, makes the racket "head heavy," i.e., the balance point
or center of gravity lies closer to the head end of the racket
than the handle end. Frolow does not describe a badminton
racket, which is distinctly different than a tennis racket in
shape, weight, and other physical characteristics.
Strauch et al. U.S. Patent No. 5,062,634 describes a
"head heavy" squash racket. The racket is light and has a
balance point or center of gravity closer to the head than the
handle. Strauch et al. do not describe a badminton rackst which
has distinctly di~ferent physical characteristics than a squash
racket.
SUMMARY OF ~HE_INVENTION
The invention provides a badminton racket which is
significantly lighter than prior badminton rackets and which is
"head heavy." The w~ight o~ the racket is within the range of
about 7S to 85 grams, and praferably within the range o abou~
80 to 85 grams. The length of the racket i8 about 26 inches,
and the balance point or center of gravi~y is about 13.4 to 15.2
,, ~ . , ' ' .:
. , .
inches from the handle end. The moment of inertia abou~ an axis
at the end of the handle is within the range of about 700 to 780
oz. in.2, and pre~erably within the range of abou~ 730 to 765
oz. in.2, and the center of percussion is about 18.7 to 20.s
inches from the handle end of the racket.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more comp~ete understanding of this invPntion one
should now re~er to the embodiment illustrated in greater detail
in the accompanying drawings and described below by way of an
example of the invention. In the drawings:
FIG. 1 is a plan view of a badminton racket frame
formed in accordance with ~he lnvention:
FIG. 2 is a side elevational view of the racket frame;
FIG. 3 is a sectional view taken along the line 3-3 of
FIG. 1.;
FIG. 4 is a sectional view taken along ~he line 4-4 of
FIG. l;
FIG. 5 is a sectional view taken along the line 5-5 of
FIG. 1;
FIG. 6 is a sectional view taken along the line 6-6 of
FIG. l;
FIG. 7 is a sectional view taken along the line 7 7 of
FIG. l;
FIG. 8 is a sectional view taken along the line 8-8 of
FIG. l;
-- 3 --
~3J) ~ j J ,~
FIG. 9 is a sectional view taken along the line g~g o~
FIG. 1;
FIG. 10 is a sectional view taken alony the line 10-10
of FIG. 1:
FIG. 11 is a sectional view taken along the line 11-11
of FIG. 1;
FIG. 12 is a sectional view taken along the line 12-12
of FIG. l;
FIG. 13 is a sectional view taken along the line 13-13
of FIG. l; and
FIG. 14 is a sectional view taken along the line 14-14
of FIG. 1.
While the following disclosure describes the invention
in connection with one embodiment, one should understand that
the` invention is not limited to this embodiment. Furthermore,
one should understand ~hat the drawings are not to scale and
that graphic symbols, diagrammatic representations, and
fragmentary views, in part, illustrate the embodiment. In
certain instances, the disclo~ure may not include details which
are not necessary gor an understanding of th~ present
invention.
DETAILED DESCRIPTION OF
THE DRAWINGS AND_EMBODI~EN~S
Referring to FIGS. 1 and 2, the numeral 20 designates a
badminton racket of the present invention. ~his racket has a
frame 21 which includeæ a hoop-shaped head portion 22 at one
,~ . . . . . . .
i7J ~ ~3 3 ~ J
end, a generally T-shaped throat portion 23, and an elongated
shaft portion 24 at the other, opposite end. The shaft portion
terminates in a handle portion 25.
The head portion ~upports conventional string 26 with
longitudinal and transverse portions which provide a
conventional strung surface. The outer surface of the head
portion 22 has a groove 27 (See FIGS. 3 and 4) to accommodate
the cross-over portions of the strings; and drilled openings 28
in the head portion 22, through which the string extends, help
define a pattern for the string.
The racket has a conventional butt cap 29 mounted on
the butt end 30 of the handle portion 25. It also includes a
flexible strip of leather or synthetic material 31 (See FIG. 14)
spirally wound around the handle portion to provide a hand
grip. Finally, it include~ a bumper guard 32 which lies in the
groove 27 and includes eyelets sized to fit into the openings
28. The guard 32 i~ a nylon member, or a member made out o~ any
other suitable material. The racket string 26 extends through
its eyelets and secures it in place (Sea FI~S. 1-3~.
Preferably, the frame comprises molded graphite fibers
and resin, although other materials may also form the frame,
e.q., aluminum, graphite rein~orced aluminum, polymers, fiber
reinforced metal~, etc. The frame's shape and cross section
make it lighter than conventional badminton rac~et frames and
head heavy.
The particular racket iIlustrated in FIGS. 1 and 2 has
~ ,
`a weight within the range of about 75 to 85 grams, and
preferably within the range of about 80 to 85 grams. The
overall length L of the racket i5 26 inches, and the balance
point or center of gravity is 13.4 to 15.2 inches from the butt
end 30 of the racket. The end moment of inertia of the racket
about an axis G-G is from 700 to 780 oz. in.2, and preferably
from 730 to 765 oz. in.2. ~he axi~ G-G extends
perpendicularly to the handle portion 25 at the butt end 30.
The moment o~ inertia about an axis Y-Y, lying perpendicularly
of the axis G-G along the center of the racket and extending
through the center of gravity, is from 9 to 12 oz. in.2. The
moment of inertia about an axis X-X, extending through the
balance point or center of gravity and lying parallel to the
axis G-G is from 160 to 220 oz. in.2.
The center of percussion of a racket is the point at
which a ball striking a freely suspended racket will cause the
racket to rotate about the axis G-G without moving the axis
G-G. Prior badminton rackets generally have a center of
percussion less than 18.54 inches from an axis at tha butt end
30. The racket illustrated in FIGS. 1 and 2 has its center of
percussion at 18.90 inches from the butt end 30 when measuring
the center of percussion with respect to the axis G-G at the
butt end. Whan measuring the center of percu~sion with respect
to an axis which lies parallel to the axis G-G but 3 inches from
the butt end 30, ths center of percussion is 17.4 inches from
that axis toward the head end 33.
., .. . , . ~ .
2 ~ 3$
The following parameters ~urther define the
configuration o~ the racket of the present invenkion which
includes a generally oval head. The longitudinal dimension A of
the strung surface, which is the inside dimension of the head
portion, is 9.32 inches. This dimension may be w.ithin the range
of 9.3 to 11.0 inches. The transverse dimension B of the strung
surface is 7.24 inches. This dimension may be within the range
of 7.0 to 8.6 inches. The length D of the handle portion 25 is
5.16 inches.
FIGS. 3-14 illustrate the height H and width W of the
cross section of the ~rame at Sections 3-3 through 12~12,
respectively. The height and width o~ the cross sections vary
along the length of the framQ a~ shown in FI~. 2. The height H
and width W of the crsss section~ of one exampl~ o~` the racket
appear below in Table I.
TABLE I
Cross H~ight Width
Section (inçh~ flnchL
3-3 0.433 O.lg5
4-4 g.494 0.235
5-5 0.542 0.268
6-6 0.551
7-7 0.486 0~41
8-8 0.315 (Diameter)
9-9 0.394 ~Diameter~ -
lQ-10 0.504 0.512
ll_11 0.906 0.92~
12-12 0.827 ~.g46
The height and width o~ sections 13-13 and 14-14 varies bàsed on
the size handle of the rack t, The height of the ~rame at ~hese
sec~ions varies between 0O827 to 1.0~3 inches and the width
varies between 0.906 to 1.000 inches. ~s shown in FIGS. 3-12,
the racke~ frame is hollo~u
- 7 -
.
. ;
- one forms the racket Or the present invention using
conventional fabrication methods. They include forming the
frame by laying graphite fibers and resin around an elongated
inflatable bladder, arranging the bladder in the shape of the
frame, curing the resin under heat and pressure, and de~lating
the bladder and removing it to provide a hollow frame.
Subsequent steps include the assembly of the frame and the guard
and handle components and the stringing of the racket.
While the above description and the drawings illustrate
one embodiment, one should understand, o~ course, that the
invention is not limited to this embodiment. Those skilled in
the art to which the inventio~ pertains may make modifications
and other embodiments employing the principles of this invention
particularly upon considering the foregoing teachings. For
~xample, rather than having the bumper guard described above,
the badminton racket of the present invention may include a
frame with a thicker portion at the head end 33 to increase the
weight on the head side of the racket and help provide the "head
heavy" feature.
The applicant, thsre~ore, by the appended claims,
intends to cover any modifications and other embodiments as
incorporate those features which constitute the essentia~
~eature~ of thi~ invention.
I claim:
