GB1582036A - Racket - Google Patents

Description

(54) RACKET (71) I, GUNNAV PER MAGNUMS GÖVANSSON, a Swedish Subject of Folkungagatan 136, S-11630 Stockholm, Sweden, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a racket having its head built up by crossing strings fastened to a frame, for example a tennis racket.

A conventional tennis racket has both surfaces of the head built up by the strings substantially plane and topped strokes in which the racket is caused to move upwards at the same time as it is moved towards the ball give to the ball a rotary motion called overspin around a substantially horizontal axis through the centre of the ball. At such strokes the ball tends to slide uncontrollably on the substantially plane surface of the racket head.

According to the present invention I provide a racket with its head built up by crossing strings fastened to a frame, wherein at least a portion of each of the two playing surfaces of the said head has a concave profile as hereinafter defined in at least one and the same dimension of the said head.

By the term concave profile is herein meant a surface having a curvature that presents a hollow to the point of observation; incurvated.

The invention will be more fully understood from the following description given by way of example only with reference to the figures of the accompanying drawing in which: Figure 1 is an elevation of one embodiment of a racket of the invention.

Figure 2 is a cross section much enlarged taken on the section station 11-11 of Figure 1.

Figure 3 is a view in oblique perspective of, again much enlarged, a crossing point between two strings of the racket of Figure 1 spaced apart by a distance piece.

Referring now to the figures of the drawing a tennis racket is seen to comprise a handle 1 that is joined to a frame 2 having crossing strings 3 and 4 that are fastened for the formation of two substantially identical playing surfaces one at each side of the racket. Distance pieces 5 have been mounted between the strings 3 and 4 at certain crossing points as illustrated in Figure 3. The cross section of Figure 2 shows in an exaggerated manner that the distance pieces 51, 52, 53, 54 have an increasing thickness tl, t2, t3, t4, from the centre of the racket head outward towards the racket frame 2 viewed in the transverse (XX) dimension of the racket head. However, in this embodiment the distance pieces 5 mounted along one and the same string 3 in the longitudinal dimension (YY) have the same thickness.

By means of the distance pieces 5 designed and placed as shown both playing surfaces of the racket head receive substantially identical concave profiles P1, P2, P3, P4 (shown by dashed lines in Figure 2) in the transverse direction including a substantial plane centre portion which laterally towards the racket frame is transformed into slightly inclined portions which in turn are transformed into plane portions adjacent to the frame. The latter plane portions may be obtained by using distance pieces having constant thickness or by excluding the distance pieces in the portions adjacent to the frame. In the same way the plane centre portion can be obtained by using very thin distance pieces having constant thickness or as illustrated in Figure 3 by excluding the distance pieces in that portion.However, the use of thin distance pieces gives the positive effect that the tendency of the strings to be displaced relatively to each other is reduced when the ball and the strings connect.

One effect of providing both playing surfaces of the racket head with a concave portion according to the embodiment described is that even if the player makes a slight misjudgement of a topped or sliced stroke the ball does not tend to slide along the surface in an uncontrollable way. Further. the use of distance pieces results in a considerable better grip between the ball and the racket head as said pieces form impressions in the ball when it hits the racket head.

In order to improve the springing characteristic of the racket head the distance pieces are made of a flexible material and preferably the distance pieces placed closer to the racket frame are made of a more flexible material than the distance pieces placed closer to the centre of the racket head. By selecting the material of the distance pieces so that it render a high friction against the strings the advantage is also obtained that the tendency of the strings to be displaced relatively to each other, when the ball and the strings connect, is reduced. For instance the distance pieces can be made of so called friction rubber. Further, the distance pieces are manufactured with such thicknesses that any desired profile can be obtained.

In the above described embodiment the main surfaces of the racket head have a concave profile only in the transverse dimension (XX). However, a corresponding profile may naturally also be obtained in the longitudinal dimension (YY) by inserting distance pieces along the longitudinal strings 3 which distance pieces have an increasing thickness from the centre of the racket head outward towards the frame.

Further, the plane centre portion may be eliminated by using also in said portion distance pieces having a decreasing thickness towards the centre of the racket head.

In that case the concavity will begin at the centre of the racket head. Further, distance pieces having an increasing thickness from the centre of the racket head and towards the frame can be inserted in all the crossing points between the strings which will result in a concavity of pyramidal form. The distance pieces can also be so selected that the slopes defining the concavity can have different distances in different directions.

It is preferred to use distance pieces for obtaining the desired concavity as then identical concavities are obtained on each side of the racket head. However, there are clearly other possibilities such as the use of relatively thick strings that are ground down to give the desired concave profile.

WHAT I CLAIM IS:- 1. A racket with its head built up by crossing strings fastened to a frame, wherein at least a portion of each of the two playing surfaces of the said head has a concave profile as hereinbefore defined in at least one and the same dimension of the said head.

2. The racket according to claim 1, wherein each of said surfaces of the head has a portion with a concave profile in the transverse direction of the head.

3. The racket according to claim 2, wherein said concave profile comprises a substantially plane portion at its centre.

4. The racket according to claim 2, wherein said concave profile is transformed into a plane portion adjacent to the frame.

5. The racket according to any preceding claim, wherein distance pieces of different thicknesses are arranged between the strings at at least some crossing points therebetween for obtaining said concave profile.

6. The racket according to claim 5, wherein said distance pieces are flexible.

7. The racket according to claim 6, wherein distance pieces placed closer to the frame are more flexible than distance pieces placed closer to the centre of the head.

8. The racket according to claim 5, wherein the material of said distance pieces give a high friction against the racket strings.

9. A racket constructed and arranged substantially as herein described and as shown in the figures of the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. impressions in the ball when it hits the racket head. In order to improve the springing characteristic of the racket head the distance pieces are made of a flexible material and preferably the distance pieces placed closer to the racket frame are made of a more flexible material than the distance pieces placed closer to the centre of the racket head. By selecting the material of the distance pieces so that it render a high friction against the strings the advantage is also obtained that the tendency of the strings to be displaced relatively to each other, when the ball and the strings connect, is reduced. For instance the distance pieces can be made of so called friction rubber. Further, the distance pieces are manufactured with such thicknesses that any desired profile can be obtained. In the above described embodiment the main surfaces of the racket head have a concave profile only in the transverse dimension (XX). However, a corresponding profile may naturally also be obtained in the longitudinal dimension (YY) by inserting distance pieces along the longitudinal strings 3 which distance pieces have an increasing thickness from the centre of the racket head outward towards the frame. Further, the plane centre portion may be eliminated by using also in said portion distance pieces having a decreasing thickness towards the centre of the racket head. In that case the concavity will begin at the centre of the racket head. Further, distance pieces having an increasing thickness from the centre of the racket head and towards the frame can be inserted in all the crossing points between the strings which will result in a concavity of pyramidal form. The distance pieces can also be so selected that the slopes defining the concavity can have different distances in different directions. It is preferred to use distance pieces for obtaining the desired concavity as then identical concavities are obtained on each side of the racket head. However, there are clearly other possibilities such as the use of relatively thick strings that are ground down to give the desired concave profile. WHAT I CLAIM IS:-

1. A racket with its head built up by crossing strings fastened to a frame, wherein at least a portion of each of the two playing surfaces of the said head has a concave profile as hereinbefore defined in at least one and the same dimension of the said head.

2. The racket according to claim 1, wherein each of said surfaces of the head has a portion with a concave profile in the transverse direction of the head.

3. The racket according to claim 2, wherein said concave profile comprises a substantially plane portion at its centre.

4. The racket according to claim 2, wherein said concave profile is transformed into a plane portion adjacent to the frame.

5. The racket according to any preceding claim, wherein distance pieces of different thicknesses are arranged between the strings at at least some crossing points therebetween for obtaining said concave profile.

6. The racket according to claim 5, wherein said distance pieces are flexible.

7. The racket according to claim 6, wherein distance pieces placed closer to the frame are more flexible than distance pieces placed closer to the centre of the head.

8. The racket according to claim 5, wherein the material of said distance pieces give a high friction against the racket strings.

9. A racket constructed and arranged substantially as herein described and as shown in the figures of the accompanying drawing.