GB2186804A - A racket - Google Patents

Abstract

In a racket for a game such as tennis, squash or badminton having an oval head holding a latticework face of strings in tension, at least one, at least part circumferentially extending, inwardly opening, recess (8) is formed in the inner peripheral surface (4a) of the head for providing an enlarged string span, to reduce the vibration effect on striking an object such as a ball and to reduce the pneumatic resistance on swinging the racket. A vibration attenuator (9) of elastic material may be inserted in the recess (8). String protectors (7) may be inserted into stringing holes (5). <IMAGE>

Description

SPECIFICATION A racket This invention relates to a racket for a game such as tennis, squash or badminton and more particularly relates to a racket having a face formed by a latticework of strings held in tension by a substantially oval head.

Recent development of rackets such as ten- nis rackets covers a wide variety of types from wooden tennis rackets through metal tennis rackets to FRP rackets. Concurrently, a wide variety of materials has been used for strings providing the face of a racket.

Most conventional tennis rackets have a general construction in which a head connection to a grip via a yoke has a substantially oval shape rim defining a face formed by a latticework of strings held in tension by the head. The head includes a pair of longitudinally opposed centre zones located astride the major axis of the oval, a pair of laterally opposed centre zones located astride the minor axis of the oval, and four intermediate zones each interspacing two adjacent centre zones.

The head also has an inner peripheral surface and an outer peripheral surface, both perpendicularly intersecting the plane of the face of the racket. The head is provided with a first group of through holes each of which extends parallel to the major axis of the oval and opens through the inner and outer peripheral surfaces of the head. A second group of through holes is provided in the head, each of which extends parallel to the minor axis of the oval and opens through the inner and outer peripheral surfaces of the head. Each string is held in tension by the head in an arrangement such that, on the outer peripheral surface of the head, the string runs in the circumferential direction astride the section of the outer peripheral surface between adjacent through holes of a same group.A tubular string protector is inserted into each through hole for protection of the associated string against vibration caused by striking balls.

When a string vibrates in a direction perpendicular to the face of the racket on striking a ball, its node of vibration is located at the inner end of the through hole through which the string passes. As a consequence, the string span is fixed by the dimension of the inner peripheral surface of the head. This restricts enlargement in effective surface area of the face of the racket thereby seriously impairing the feel of the racket in the hand on striking a ball.

For reduced vibration, it has been proposed that the string protectors project further from the inner peripheral surface of the head, in particular in the longitudinal and lateral central zones. Presence of such long projections not only mars design of the racket but also increases pneumatic resistance on swinging of the racket, thereby causing an uncomfortable feel in the hand.

Vibrations of the string when striking a ball are transmitted to the player's hand via the head, the yoke and the grip and often cause fatigue of the wrist. In order to reduce such string vibrations, it has been proposed to wind a rubber strip or strap directly onto each string of the racket. Attachment of such rubber strips greatly mars design of the racket and often causes increased pneumatic resistance when the racket is swung, together with the production of unpleasant noises.

There is thus a need for a generally improved racket for a game such as tennis, squash or badminton with an enlarged string span, reduced string vibration when striking an object such as a tennis ball and less pneumatic resistance when swung.

According to the present invention there is provided a racket for a game such as tennis, squash or badminton, including a head having a pair of longitudinally opposed centre zones and a pair of laterally opposed centre zones, and a latticework formed by strings held in tension by said head between a peripheral portion of said head, wherein said head is provided with at least one, at least part circumferentially extending, inwardly opening, recess formed at least locally in an inner peripheral surface of the pheripheral portion, through which at least one recess at least some of the strings pass into the peripheral portion of the head, said at least one recess being operative to increase the string span available for vibration on striking an object such as a ball and thereby to reduce the vibration effect.

Preferably the racket includes a vibration attenuator, made of an elastic material, inserted in said circumferentially extending recess or recesses, through which vibration attenuator at least some of the strings pass into the head peripheral portion.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a plan view from above of one example of a racket to which the present invention is advantageously applied.

Figure 2 is a sectional view taken along a line ll-ll in Fig. 1, showing one embodiment of the present invention, Figure 3 is a fragmentary, perspective view of the racket part shown in Fig. 2, Figure 4 is a sectional view taken along the minor axis X-X in Fig. 1, showing the mechanism of string vibration on the racket shown in Figs. 2 and 3, Figure 5 is a fragmentary, perspective view of similar to that of Fig. 2, showing another embodiment of the present invention, Figure 6 is a sectional view, taken perpendicular to the face, of one example of a conven tional tennis racket, and Figure 7 is a sectional view, taken along the minor axis of the oval head, of the conventional tennis racket of Fig. 6, showing the mechanism of string vibration.

In the preferred embodiment of the present invention, at least one, at least part circumferentially extending recess is formed in the inner peripheral surface of a peripheral portion of a head 4 of a racket frame 1 in longitudinal centre zones 4B and lateral centre zones 4A astride the major and minor axes Y and X of the oval shape head 4 shown in Fig. 1, However, the recess or recesses may be formed in intermediate zones 4C and 4D also.

In the first embodiment of the present invention shown in Figs. 2 and 3, the racket frame 1 has a foam resin core 2 and a FRP shell 3 totally covering the core 2. The head 4 also has an inner peripheral surface 4a and an outer peripheral surface 4b, both perpendicularly intersecting the plane of the face of the racket. The head 4 is provided with through holes 5, a first group of which extend parallel to the major axis of the oval and a second group of which extend parallel to the minor axis of the oval. A part circumferential recess 6 is formed in the outer peripheral surface 4b of the head 4 connecting two adjacent through holes 5 and each string G is located in tension in the circumferential recess 6 astride the section or portion of the outer peripheral surface 4b lying between the two adjacent through holes 5.A string protector 7, which is made up of a flange section 7a and a tubular section 7b, is inserted into the through holes 5 between the holes and the strings for protection of the associated string G against vibration caused by a ball striking the racket strings.

In accordance with the present invention, at least one, at least part circumferentially extending, inwardly opening, recess 8 is at least locally formed in the inner peripheral surface 4a of the head 4 as shown in Figs. 2 and 3.

In this embodiment, such circumferential recesses 8 are provided in the longitudinal and lateral centre zones 4B and 4A. As stated already, the node (P) of string vibration is located at the inner end of the through hole 5 that the string G passes through. The length of the string protector 7 projecting from the inner end of the hole 5 is (I).

The construction shown in Figs. 2 and 3 of the present invention will now be compared with the conventional construction shown in Figs. 6 and 7. Like elements are indicated by like reference numerals in both pairs of draw ings. It will be clearly seen that the node (P) of string vibration in Fig. 2 is located closer to the outer peripheral surface 4b than the node (Pc) of string vibration in Fig. 6. As a consequence, the vibrating string span (L) in Fig. 4 is clearly larger than the vibrating string span (Lc) in Fig. 7, thereby improving the feel of the racket when striking a ball or like object, and reducing the vibration effect.

The projecting length (I) of the tubular section 7b in Fig. 2 is equal to the projecting length (Ic) in Fig. 6. Due to presence of the circumferential recess 8 in the inner peripheral surface 4a, however, the substantial degree of intrusion of the string protector 7 into the region of the face in Fig. 2 is smaller than that in Fig. 6. As a consequence, the design is less marred and the pneumatic resistance on swinging is less in the construction shown in Fig. 2 than the conventional construction shown in Fig. 6.

Such circumferential recesses are easily formed during heat moulding of the racket frame. For example, circumferential projections are formed on the inner walls of the mould at positions corresponding to the positions of the circumferential recesses to be made in the moulded racket frame.

In a preferred embodiment of the present invention as shown in Fig. 5, a vibration attenuator 9 made of an elastic material such as rubber and plastics may be securely inserted into the circumferential recess 8.as a substitute for the conventional rubber strap or strip.

The vibration attenuator 9 is provided with through holes 10 at positions in line with the through holes 5 in the head 4. Absence of any significant projection on the inner peripheral surface 4a greatly improves the design and reduces pneumatic resistance on swinging of the racket. The elastic material for the vibration attenuator 9 should preferably have a Shore D hardness in a range from 20 to 50 and a Shore A hardness in a range from 60 to 90.

Claims (5)

1. A racket for a game such as tennis, squash or badminton, including a head having a pair of longitudinally opposed centre zones and a pair of laterally opposed centre zones, and a latticework formed by strings held in tension by said head between a peripheral portion of said head, wherein said head is provided with at least one, at least part circumferentially extending, inwardly opening, recess formed at least locally in an inner peripheral surface of the pheripheral portion, through which at least one recess at least some of the strings pass into the peripheral portion of the head, said at least one recess being operative to increase the string span available for vibration on striking an object such as a ball and thereby to reduce the vibration effect.

2. A racket according to claim 1, having a plurality of said at least part circumferentially extending, inwardly opening recesses, formed in said longitudinally opposed centre zones and in said laterally opposed centre zones.

3. A racket according to claim 1 or 2, in cluding a vibration attenuator, made of an elastic material, inserted in said circumferenti ally extending recesses or recesses, through which vibration attenuator at least some of the strings pass into the head peripheral portion.

4. A racket according to claim 3, wherein the or each vibration attenuator is in the form of a strip of elastic material having a Shore D hardness in the range of from 20 to 50 and a Shore A hardness in the range of from 60 to 90.

5. A racket for a game such as tennis, squash or badminton, substantially as hereinbefore described, with reference to Figs. 1 to 4 or Figs. 5 of the accompanying drawings.