| US3647211A | 1972-03-07 | |||
| US2171223A | 1939-08-29 | |||
| NL8501679A | 1987-01-02 | |||
| GB2137511A | 1984-10-10 | |||
| BE905311A | 1986-12-16 |
| 1. | Tennis racket consisting of a head portion (1) which supports stringing (2), a handle (3) and an intermediate portion (5) which is arranged between said handle and said head and which is provided with a heartshaped portion (6) connected to said head, which heartshaped portion (6) has at least one zone (7) of which the crosssectional height is less than the thickness of the handle (3) and less than the maximum crosssectional height of said head portion (1), char¬ acterized in that the crosssectional height of the head (1) decreases continuously from a point located at an interval from the heartshaped portion (6) towards said heartshaped portion (6) and towards the top of the head. |
| 2. | Tennis racket as claimed in claim 1, character¬ ized in that the head portion (1) has a convexly curved form. *****. |
The invention relates to a tennis racket consisting of a head portion which supports stringing, a handle and an intermediate portion which is arranged between the handle and the hea.d and which is provided with a heart-shaped portion connected to the head, which heart-shaped portion has at least one zone of which the cross-sectional height is less than the thickness of the handle and less than the maximum cross-sec¬ tional height of the head portion.
A tennis racket of the kind is known from DE-U-870- 7166.
A tennis racket has to satisfy many requirements. One of these requirements is that when a tennis ball is struck the deviation of the head from a position in the length direc¬ tion of the longitudinal axis must be restricted. If the rac- ket fails to satisfy this requirement, it will not be possible to strike the ball in a controlled way or place it accurately. Another demand is that vibrations resulting from the natural resonant frequency of the head are transmitted as little as possible to the handle. Otherwise, there arises a danger of causing "tennis elbow".
The invention has for its object to produce a tennis racket that meets the above-stated requirements.
This is achieved according to the invention through the cross-sectional height of the head decreasing continuously from a point located at an interval from the heart-shaped portion towards the heart-shaped portion and towards the top of the head.
As a result of adopting this arrangement, the dis¬ tribution of flexural stiffness over the head is optimized. The flexural stiffness reduces towards both the top of the racket and towards the handle, whereby the transmission of vibrations to the handle is minimized through the narrower
cross-section in the heart-shaped portion. It is recommended that the head has a convexly curved form.
The invention will be elucidated by reference to the drawings. Figure 1 shows a perspective view of the tennis racket according to the invention, and
Figure 2 shows a cross-sectional view of the tennis racket of figure 1.
The head portion 1 comprises a stringing 2 in the usual fashion. The handle 3 is covered using a wound covering 4 and is connected to the head portion 1 via the intermediate portion 5, which comprises a heart-shaped portion 6. The in¬ termediate portion 5 contains a zone 7 which has a cross-sec¬ tional height less than the thickness of the handle 4 and less than the greatest cross-sectional height of the head portion.
The head portion has a profile which tapers from a region 8 towards the top portion 9 and towards the heart-shap¬ ed portion 6. Consequently, when the ball is struck by the end portion 9 the transmission of vibrations to the handle 3 is minimized, since a region 8 has a relatively high flexural stiffness.
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