Abstract:
A tennis racquet frame including a handle, a rim and arms connecting the handle and the rim and wherein each arm includes two fingers extending one above and one below the rim when the racquet frame is laid flat on a support surface.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a tennis racquet frame, its method of manufacture, and a racquet comprising such a frame. 
     2. Description of the Related Art 
     In the conventional way, a tennis racquet frame comprises a handle, a rim, and two diverging arms connecting this handle to this rim. In the case of a conventional composite racquet, a “preform” combining the handle, arms and most of the rim is made first. Then a connecting region, also known as the “yoke”, is made, forming the bridge of the racquet, and the whole assembly is placed in a mould. 
     SUMMARY OF THE INVENTION 
     Against this background, it is an object of the invention to provide a tennis racquet frame that offers an alternative to the known solutions. It is particularly intended to provide such a frame in which the structure is more modular than is the structure of prior art racquets. 
     For this purpose the invention relates to a tennis racquet frame comprising a handle, a rim and arms connecting this handle and this rim, said frame being characterized in that each arm comprises two fingers extending one above and one below the rim when the racquet frame is laid flat. 
     Other features are as follows:
         each arm comprises a base continuing on from the handle, from which there extend the two fingers;   the two fingers comprise a free region in which they define a void, and a region of mechanical connection to the rim;   the free end of the mechanical connection region of each finger defines a straight line forming, with a central transverse straight line of the rim, an angle of between −60° and +30°;   the mechanical connection region occupies an angular sector of between 10 and 90°, preferably between 30 and 60°;   the two fingers of each arm are moulded integrally with the rim;   the two fingers and the rim are formed by a single tubular member;   the two fingers are formed from a first tubular member, while the rim is made from a second tubular member;   the rim is fixed permanently to the two fingers of each arm, particularly by welding or adhesive bonding;   the two fingers of each arm are fixed removably to the rim, particularly by snap-fastening or screw-fastening;   this frame is made in one material, particularly a carbon-based composite material;   the handle and the two arms are made of one material, while the rim is made of another material.       

     The invention also relates to a method of manufacturing the above racquet frame, in which a preform combining the handle and the two arms on the one hand, and a preform of the rim on the other, are produced, these two performs are then both placed in the same mould, and the final racquet frame is formed. 
     The invention also relates to a method of manufacturing the above racquet frame, in which a first element formed of the handle and of the arms on the one hand, and a second element forming the rim on the other, are produced, and these two elements are fixed to each other. 
     Lastly, the invention relates to a tennis racquet comprising a frame as above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described below with reference to the accompanying drawings, which are given purely by way of non-restrictive examples. In the drawings: 
         FIGS. 1 to 3  are perspective, front and side views, respectively, of a tennis racquet frame in a first variant of the invention; 
         FIGS. 2A and 2B  are front views, similar to  FIG. 2 , showing two alternative embodiments of the racquet frame of the invention; 
         FIG. 3A  is an enlarged view from  FIG. 3 ; 
         FIG. 4  is a cross section on the plane marked IV-IV in  FIG. 3 ; 
         FIG. 5  is a cross section on the plane marked V-V in  FIG. 4 ; 
         FIG. 6  is a front view showing in schematic form a step of manufacturing a tennis racquet frame in a first variant of the invention; 
         FIGS. 7 and 8  are a longitudinal cross section and transverse cross section, respectively, similar to  FIGS. 4 and 5 , showing the racquet frame in this first variant; and 
         FIG. 9  is a schematic view, similar to  FIG. 6 , of another variant of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The tennis racquet frame shown in  FIGS. 1 to 3  comprises in the usual way a handle  2 , shown partially, and a rim  4 , in which strings (not shown) may be strung. There are also two connecting arms  6  which diverge, with reference to the front view,  FIG. 2 , from the handle  2  to the rim  4 . As can be seen in  FIGS. 3 and 3A , which are side views, each arm  6  is roughly Y-shaped in the sense that it has a base  8  continuing on from the handle  2 , and two fingers  10   1  and  10   2  that extend between this base  8  and the rim  4 . 
     These fingers  10   1  and  10   2  are separated from each other and roughly parallel. At the end nearest the base  8 , these fingers initially define a void marked E. The fingers then pass over the rim  4 , one above and one below it, when the racquet is laid flat. 
     To facilitate the reading of the description, certain geometrical definitions of the racquet frame will now be given with reference to  FIGS. 2 ,  2 A and  2 B. In these figures A is the main axis of the racquet, corresponding to that of the handle and therefore vertical when the racquet is stood on the end of this handle. D is the central transverse straight line perpendicular to the above-mentioned axis A: it passes through the widest part of the rim  4 . Finally, C is the centre of the racquet, corresponding to the intersection between this main axis A and this central transverse straight line D. 
       FIGS. 1 and 2  show the base  8 , a first region  10 ′ in which the fingers define the abovementioned void E, and a mechanical connection region  10 ″ in which these fingers are attached to the rim. In the example illustrated, this connection region  10 ″ extends approximately as far as a central region of the rim, defined by the abovementioned straight line D. In other words the free ends E 1  and E 2  of these fingers lie on this straight line D. 
     However, in a variant, this mechanical connection region  10 ″ may extend past the straight line D, or on the contrary end short of it. Thus, in  FIG. 2A , the free ends E′ 1  and E′ 2  of the two fingers  10   1  and  10   2  extend past the straight line D, that is towards the tip of the racquet. The angle β 1  formed by the abovementioned straight line D and the straight line D 1  connecting the centre C and the end E′ 1  thus has a value of as much as +30°. 
     On the other hand, in  FIG. 2B , the ends E″ 1  and E″ 2  are situated between the handle  2  and the straight line D. In this situation the angle β 2  formed by this straight line D and the straight line D 2  connecting the centre C and the end E″ 2  may be as much as −60°. By definition, in these  FIGS. 2A and 2B , the value of the angle β is negative when the free ends of the fingers are towards the handle, and positive when they are placed towards the tip of the racquet. 
     Referring again to  FIG. 2 , α is the angular sector occupied by the mechanical connection region  10 ″. This sector is defined by the free end E 1  and E 2  of each finger which is located on the transverse straight line D in this  FIG. 2 , and by the straight line D′ connecting the centre C and the point of transition T between the free region  10 ′ and the mechanical connection region  10 ″. In this situation, α is advantageously between 10 and 90°, preferably between 30 and 60°. 
     To manufacture the frame described above, a preform comprising the handle  2 , the arms  6  and most of the rim  4  is first made in the usual way. This assembly is then placed in a mould and a bridge  12  is inserted, so as to form the complete rim, in accordance with a routine operation. Lastly, the racquet is moulded finally by blow moulding. 
       FIG. 4  is a longitudinal cross section through the racquet, taken in the region of the free end of the fingers  10   1  and  10   2 . As this figure shows, a single tube  14  forms the fingers  10   1  and  10   2  of each arm, and the rim  4 . This is also shown in  FIG. 5 , which is a transverse cross section through the rim and through the two fingers  10   1  and  10   2  situated on either side of the latter. 
     It will be seen that in this first illustrative embodiment, certain parts of the racquet frame may be made of one material, while other parts of the frame are made of a different material. For example, the material of the rim  4  may differ from the material both of the handle  2  and of the arms  6 . 
       FIGS. 6 to 8  show a first variant of the invention. Here, two preforms are made, both using the same mouldable material, or two compatible mouldable materials. The first of these preforms  100 , which is Y-shaped, includes the handle  102  as well as the two arms  106 , each of which comprises two fingers  110   1  and  110   2 , as before. Furthermore, the second  101  of these preforms will form a rim  104 . 
     Once these preforms are made, by any appropriate conventional technique, they are placed in a single mould and joined together for example by putting into the mould, before the blow-moulding operation, preimpregnated carbon fingers or “tapes” along the mechanical join region. The differences between this second embodiment and that described with reference to  FIGS. 1 to 5  are more particularly highlighted in  FIGS. 7 and 8 , which are cross sections similar to those of  FIGS. 4 and 5 . 
     These figures thus show that the rim  104  and the fingers  110   1  and  110   2  of each arm  106  are not formed by a single tube, as in the first embodiment. Instead, two tubes  114   1  and  114   2  belonging to the first preform  100 , may be seen to define the two fingers  110   1  and  110   2 . There is also a central tube  114   3 , belonging to the second preform  101 , which defines the rim  104 . 
     This second embodiment has advantages in terms of modularity since it makes it possible to produce very conveniently a racquet frame formed of different materials and thus makes it possible easily to modify the mechanical behaviour of the racquet. 
       FIG. 9  shows a third embodiment of the invention, in which two elements  200  and  201  which are to form the final racquet frame may be seen. However, unlike the preforms  100  and  101 , the elements  200  and  201  are “final”, in the sense that they will not go through a subsequent moulding operation. 
     The first element  200 , similar in its geometry to the preform  100 , combines the handle  202  and the two arms  206 , each of which is formed of two fingers  210   1  and  210   2 . The second element  201 , which is similar in its geometry to the preform  101 , also forms the rim  204 . To make the final frame, the element  201  is attached to the element  200  by any appropriate fixing means. 
     First and foremost this may be a permanent fixing. A non-restrictive example that may be cited is adhesively bonding or welding together these two elements  200  or  201 . 
     Alternatively the element  201  may be fixed removably to the element  200 . For this purpose it may for example be snap-fastened or screw-fastened. 
     The embodiment illustrated with reference to  FIG. 9  has the particular advantage of allowing the use of elements made from different materials. Thus, the Y-shaped element  200  can be made of a composite material, while the element  201  is then made of another composite material, or of a metal. The element  200  may however be made of a metallic material, while the element  201  is in this case made of another metallic material or a composite material.