Games using tangible projectile – Player held and powered – nonmechanical projector – per se,... – Racket or paddle; accessory therefor
Reexamination Certificate
1998-06-05
2001-01-30
Chiu, Raleigh W. (Department: 3711)
Games using tangible projectile
Player held and powered, nonmechanical projector, per se,...
Racket or paddle; accessory therefor
C473S539000, C473S540000
Reexamination Certificate
active
06179735
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to improvements in sporting racquets and, more particularly, but not exclusively, to improvements in methods of stringing racquets, sporting racquets with improved stringing and tools and machines for stringing and improving the stringing of sporting racquets.
BACKGROUND OF THE INVENTION
Currently available sporting racquets, for example tennis racquets, are continuously strung by passing a length of stringing material through holes in a frame, pulling the length of stringing material to a predetermined pressure and tying it off under pressure against itself. The pressure is retained within the length of stringing material. Conventionally, a single length of stringing material forms strings which run length-wise in the racquet head and a separate single length of stringing material forms strings which run cross-wise.
Because of this stringing method, the tension of each string in the racquet (the term “string” being used herein to mean one string “span” from one side of the racquet head to the other, and not the total length of stringing material) is substantially similar across the entire racquet face (the term “racquet face” being used herein to mean the strung area of the racquet head) . The “elastic quality” of a tensioned string depends upon the tension applied and the length of the string. The amount of “elastic bend back” experienced by a relatively long string in a conventional racquet head when an object is struck will be greater than that available to the shorter strings in the racquet because all the strings are at substantially similar tension i.e., the elastic properties vary in dependence on the length of the string. This can have a deleterious effect on shot playing. For example, it is well known that in tennis it is desirable to strike the ball at the centre area of the racquet face, to ensure that the ball travels in the desired direction with the desired power. At the centre area of the face of a conventionally strung tennis racquet the strings will have similar elastic properties, by virtue of the fact that the length differences between strings are at a minimum. This centre area is generally known as the “sweet spot”.
At the outer area of the racquet face the shorter and longer strings will have different elastic properties. It is well known that control and power applied by the outer area of the racquet face of a conventional tennis racquet is extremely unreliable. Hence the desirability of striking a ball with the centre of the racquet face.
Even towards the centre of the racquet face in the so-called “sweet spot”, the elastic properties of the strings vary somewhat.
In presently available sporting racquets, therefore, a perfect sweet spot does not exist and the nearest approximation to a sweet spot is located in a small area, generally towards the centre of the racquet face.
SUMMARY OF THE INVENTION
From a first aspect, the present invention provides a method of stringing a racquet, comprising the steps of independently tensioning at least a plurality of strings in the racquet and applying means for maintaining the independent tensioning.
By “independently tensioning” is meant the application of tension independently to each string of at least the plurality of strings.
The plurality of strings are preferably independently tensioned to different tensions (differentially tensioning) and the resultant differential pressures between strings maintained.
Preferably, all strings in the racquet will be independently tensioned, although embodiments are envisaged where some of the strings may be strung by prior art methods and the others independently tensioned.
In at least preferred embodiments, the ability to independently tension strings to different tensions and maintain the resultant differential pressures between strings can result in vast improvements in racquet quality. It is possible to provide a racquet face where the elastic quality is substantially even over the entire face. In other words, it is possible to provide a racquet which has a “sweet spot” across substantially the entire racquet face.
The ability to individually control tension also allows “zoning” of the racquet face. Different areas of the racquet face may display different qualities.
It is also possible to use different gauge and/or material strings in different areas of the racquet face to assist variation or provide further variation in racquet characteristics.
A “sweet spot” over the entire area of a racquet will generally be achieved by having the tension in the longest strings the greatest, stepping down the tension for shorter strings. For example, where the tension in the longest strings (the base tension) is 28 kg, then the tension in the shorter strings is set lower, say 26, 24, 22, 18 etc., depending upon their relative length with respect to the length of the longest string. We have found that stepping down, or providing differential tensions between the strings in this manner provides the best method of obtaining even elastic quality over the entire surface of the racquet.
From a second aspect, the present invention provides a method of stringing a racquet, comprising the step of tensioning at least a plurality of strings in the racquet in accordance with the following formula:
T
s
=
(
L
s
L
L
)
P
T
L
wherein,
T
S
is the tension to be applied to the particular string being tensioned, L
S
is the length of the particular string being tensioned, L
L
is the length of the longest string in the racquet, T
L
is the tension of the longest string in the racquet which is preset as the standard or base tension and P is in the range 1.7 to 2.3 inclusive.
In one preferred embodiment, P=2.
We have found that tensioning strings in accordance with this formula leads to elastic quality of the strings so tensioned being substantially similar. Where all the strings on a racquet are tensioned in this manner, this, in at least preferred embodiments, leads to a “sweet spot” over substantially the entire face of the racquet.
P2.3 has also been used with good effect. P in the range 1.7 and 2.3 may be used to provide racquets of good quality, in at least preferred embodiments.
The length of each string L, is preferably measured between the inside faces of the racquet frame, in each case.
It will be appreciated that other formulas may be devised and applied to provide racquets with different characteristics.
From a third aspect, the present invention provides a method of stringing a racquet, comprising the step of applying tension to at least a plurality of strings in the racquet so that the elastic quality of a plurality of the shorter strings substantially matches the elastic quality of a plurality of the longer strings.
As discussed above, where the elastic quality of shorter and longer strings in a racquet substantially matches, then the elastic bend back response of the racquet will be substantially even across the face of the racquet, providing more precise control/power characteristics over the racquet face than available in conventional, prior art racquets.
From a fourth aspect, the present invention provides a method of stringing a racquet, comprising the step of tensioning at least a plurality of the strings to a predetermined level so that at least a plurality of strings retain different, pre-calculated tensions, in order to provide predetermined elastic qualities for the strings, whereby to produce racquets having predetermined qualities.
Preferably, the pre-calculated tensions are calculated to provide predetermined racquet characteristics, i.e., power, spin and direction of shot provided by racquet. As discussed above, it is possible to individually tension the racquet strings to tensions which are calculated to provide a sweet-spot over the entire racquet face.
As also discussed above, any characteristic may be applied in accordance with this method. For example, different areas of the racquet may have different qualities i.e., some may be more useful for applying spin, some more useful for applying power and
Chiu Raleigh W.
Kelly Bauersfeld Lowry & Kelley LLP
LandOfFree
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