Note: Descriptions are shown in the official language in which they were submitted.
l. 2 ~ 1~22~
GAMES RACKET
This disclosure relates to games rackets,
particularly those incorporating a single shaft such
as a badminton racket. Such a racket consists
essentially of a head containing the strings attached
to a handle by means of a single shaft. The overall
stiffness of the shaft and the distribution of that
stiffness along the length of the shaft affects the
playing properties of the racket. This is because
the bending and recovery of the shaft immediately prior
to and during the action of striking the shuttlecock
can influence the head speed of the racket as it strikes
the shuttlecock, so that this can add to the overall
speed of the racket head so leading to increased speed
applied to the shuttlecock. Also, improved "feel"
can be provided to the player by this means which is
desirable for the efficient striking of the shuttlecock
and satisfaction to the player.
Increasing the flexibility of the shaft (measured
in terms of the increased deflection of the tip of
the racket when loaded at this point with the handle
rigidly clamped) generally is desirable, but this often
leads to shafts of poor durability. Also, this can
be disadvantageous in that whilst increased flexibility
in a plane through the axis of the shaft perpendicular
to the plane of the strings is desirable, it is
undesirable for flexibility to be increased in a plane
through the axis of the shaft parallel to the plane
of the strings, because this can lead to less chance
of contact with the shuttlecock being made in the centre
of the racket head.
According to the present invention a games racket
comprises a head defining interlaced strings, a shaft
and a handle, the shaft connected at a first end to
the head and at a second opposite end to the handle,
the handle having a central longitudinal axis wherein
the shaft is attached within the handle substantially
along said central axis by an anchorage means which
~1~0220
2.
substantially rigidly anchors the shaft in a direction
in the plane of the interlaced strings whilst permitting
under playing conditions elasticity to anchorage of
the shaft in a perpendicular direction to the plane
of interlaced strings so that the shaft is capable
of pivoting in said perpendicular direction about the
point where it enters said handle.
The invention relates to a method for attaching
a shaft to a handle of a racket whereby its flexibllity
is apparently increased in a direction in a plane
through its axis perpendicular to the plane of the
strings, whilst not increasing its flexibility in a
plane through its axis parallel to the plane of the
strings. This is achieved by a special way in which
the shaft of the racket is anchored in the handle in
which the anchorage allows a degree of elastic movement
in one plane, but not in another. The elastic movement
allows the shaft of the racket to rotate about a pivot
where the shaft enters the handle so that this
rotational movement is additive to flexure of the shaft
under load. In other words, the deflection of the
tip of the racket incorporating this anchorage system
is the sum of the deflection, due to the bending of
the shaft, and that due to rotation of the shaft about
its pivot point as allowed by the elasticity of the
anchorage system. The anchorage system, however, is
substantially rigid in the perpendicular plane, so
that the deflection of the tip of the racket is solely
due to flexure of the shaft in this direccion. See
Figures 1 to 4, in which:
Figure 1 is a schematic side view, i.e. in the
plane of the strings, of a racket 10
in which a head portion 11 is attached
to a shaft 12 which is attached to a
handle 13 by means of an anchorage means
l~a, positioned towards the butt end
of the handle and an elastomeric grommet
15 at the point where the shaft enters
~
;, . . . .",
2l~n22a
3.
the handle. The anchorage means
comprises a spring 14a which can move
elastically in direction AA';
Figure 2 is a schematic front view of the same
racket shown in Figure 1 and illustrates
the anchorage means 146 which cannot
move in direction BB';
Figure 3 illustrates schematically what happens
when the racket head portion 11 is
subjected to a load "L" as shown in
Figure 1 such as from striking a
shuttlecock. The spring 14a allows
the shaft to move a distance "w" and
the elastomeric grommet 15 allows the
shaft to pivot thus giving a total
deflection "w+d";
Figure 4 illustrates schematically what happens
when the racket head portion 11 is
subjected to a load "L" applied parallel
to the plane of the head as shown in
Figure 2. The substantially rigid
anchorage in this plane prevents the
end of the shaft from moving and the
total deflection of the head portion
is limited to "d", the result of pivotal
movement about the grommet 15;
Figure 5 is a sectional schematic view, which
would be in a plane perpendicular to
the plane of the strings, of part of
a games racket in which the shaft 16
is bonded into an anchorage means 17
consisting of a spring element 17 made
of an elastomeric composition. The
spring element 17 is provided with
spigots 18, pairs of which engage into
one of several pairs of holes 19
provided in the handle 20. The spring
element 17 is designed so that in the
~'.' ' ' ' A ' ~ '
211022~
4.
direction A-A' it is elastic but in
the direction B-B' it is substantially
rigid; and
Figure 6 is a sectional view through the handle
20 of Figure 5 with the spring element
anchorage means shown as an end view.
Figures 5 and 6 also show how longitudinal
location of the shaft 16 is arranged by spigots 18
in the spring element 17 locating with pairs of holes
19 in the hollow handle 20. The position of the
anchorage of the spring element can be adjusted
longitudinally by moving the spigots into different
pairs of holes and this can be arranged by increasing
or decreasing the length of the shaft to provide an
overall acceptable racket length. It will be
appreciated that the apparent flexibility of the shaft
in the plane through the shaft perpendicular to the
strings can be significantly modified by this means.
It will be appreciated that the qualities of pivot
point 21 are also an important factor. This may be
made from the same material as that of the handle,
or it may be formed of separate material which may
itself have elastic properties. Preferably the pivotal
point is flexible to prevent rattling during use of
the racket, e.g. it may be of an elastomeric material
in the form of a grommet.
The spring element may be of various
configurations provided that the requirements of rigid
location of the shaft in rotational sense and a
longitudinal sense are achieved and lateral flexibility
is only allowed in the desired plane. The material
from which the spring element is made may be metal,
rubber or plastic or a combination of these, or of
other suitable material, the difference in rigidity
properties (hardness and resilience) being due to the
compositions/conformations of the materials from which
the elements are formed.
