Abstract:
The invention refers to a novel ball game racket, especially a tennis racket with a racket head formed by a tension frame with stringing, and with a handle unit formed by a handle shaft or a racket neck joining the tension frame for example via a heart piece, and attenuating means in at least one area of the racket frame.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention refers to a ball game racket, especially a tennis racket, including a racket head formed by a tension frame with stringing and by a handle element connected to the tension frame, for example, by means of a core, and formed by a handle shaft, or a racket neck and a handle, as well attenuating means on at least one area of the racket frame.  
         [0002]     Ball game rackets, especially designed as tennis rackets, are known in most different varieties.  
         [0003]     Furthermore, hydraulic mediums, or liquids, are known to have a viscosity which can be altered by an electric, or electromagnetic field, in a controlled manner; the use of such liquids has been in connection with ski bindings (DE 195 17 417 A1).  
         [0004]     It is one object of this invention to provide a ball game racket, the characteristics of which can be altered dynamically, for example, by using the racket dependent on forces exerted upon the racket.  
       SUMMARY OF THE INVENTION  
       [0005]     The invention includes attenuating means with an attenuation fluid, the viscosity of which is controllable by an electric, and/or a magnetic field, and electric control means for altering the viscosity of the attenuation liquid.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     In the following, this invention is explained in connection with embodiments by referring to the drawings. The drawings show:  
         [0007]      FIG. 1 , in a simplified representation and in plan view, a ball game racket according to the invention designed as a tennis racket;  
         [0008]      FIG. 2  is a cross-section along line I-I of  FIG. 1  through the racket head or the tension frame;  
         [0009]      FIG. 3  is a basic representation of a circuit for adjusting the stiffness of the racket head tensioning; and  
         [0010]      FIG. 4  is a cross-sectional view along lines  2 - 2  or  3 - 3  of  FIG. 1 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     The tennis racket shown in the figures and generally marked by  1  includes a tension frame  2  forming the racket head, stringing  3  which has a plurality of crossing string lengths  4 ′, or strings  4 , and a racket neck, or racket handle shaft  6 , joining the tension frame, or its profile  2 ′ ( FIG. 2 ), across a core  5 ; the racket handle  7  joins the racket neck.  
         [0012]     The tension frame profile  2 ′, the core  5  which is formed by two diverging webs, or arms  5 ′, starting at the handle shaft  6 , as well the handle shaft  6 , form a one-piece racket frame, which according to the shown embodiment is designed as a hollow profile entirely closed from outside, or as a closed hollow frame made of suitable material, such as fiber reinforced plastic material forming a hollow profile which across its entire extension is closed outwardly.  
         [0013]     As shown in  FIG. 2 , the tension frame  2 , or the tension frame profile  2 ′, in view of the stringing  3 , is provided with an outer support profile  8  arranged outside thereof, which support profile, in the shown embodiment, embraces the tension frame profile  2 ′ over its entire length between the arms  5 ′ of the core  5 . The support profile  8  is formed symmetrically in view of a center plane, which also is the stringing plane BE, and basically comprises a hood- or wing-type profile section  9 , which is open towards the stringing  3 ; the profile section  9  with its both edges  9 ′ rests sealingly upon the frame profile  2 ′ formed by the closed hollow profile.  
         [0014]     The wing-type curved profile section  9  within the area of the stringing plane BE is formed concavely on its outer surface opposite to the stringing  3 , and forms a groove-type recess  10  embracing the racket head or tension frame  2  at the outside area. At both sides of said recess  10 , the profile section  9  within the cross-section of  FIG. 2  is curved in a substantially convex manner at its outer surface so that on both sides of the stringing plane BE, two sections are provided which in cross-section of  FIG. 2  form a concave recess  11 , at the inner side facing the stringing which recess also extends across the entire length of the supporting profile  8  parallel to recess  10 . In addition, the supporting profile  9  has sleeves or eyelets formed thereon, which extend beyond that side of the profile section  9  facing the frame  2 ′, and which are passed through bores  13  and  14  of the frame profile  2 ′. The eyelets  12  themselves have bores  15  through which the strings  3 ′ are passed in a manner known in the field of stringing tennis rackets so that the corresponding string  4  extends outwardly in an assumed direction through the bore  15  of an eyelet  12 , then extends within the recess  10  along the outer surface of the tension frame, and finally extends through a further eyelet  12 , or its bore  15 , back again to the interior, etc. With eyelets  12 , the supporting profile  8  to a certain extent is movable in the direction of the axis of the eyelets  12  in view of the frame profile  2 ′. The supporting profile  8  is preferably made of fiber reinforced plastics material in such a manner that it, or alternatively the profile section  9  thereof, acts as a blade spring, and with a racket with stringing exerts the springy force onto the strings  4  required for the stringing.  
         [0015]     With the shown embodiment, the frame profile  2 ′, at the outer surface facing the profile section  9 , is provided with a channel-type recess  16  at both sides of the stringing plane BE and distant thereof; one recess each is arranged opposite a recess  11 . Within the spaces formed by said recesses  11  and  16 , attenuating elements  17  are provided, which are in contact with the frame profile and the profile section  9 . With the shown embodiment, said attenuating elements  17  are formed by elastic hoses closed at both ends and extending across the major length of the racket head between the webs  5 ′, namely parallel to plane BE. The hoses  18  each are made of permanent elastic material, for example, of elastic plastics material, and are provided with a plurality of sections  18 ′ which are reduced in cross-section and accordingly are operating as nozzles so that in longitudinal direction each attenuating element  17  is followed by a hose section  18 ″ with a large inner cross-section and a hose section  18 ′ with reduced cross-section in an alternating manner. The attenuating elements  17 , or the hoses thereof, are filled with liquid attenuation means, with a hydraulic medium, or a liquid, the viscosity of which can be altered by an electric and/or a magnetic field.  
         [0016]     Liquids or media (dispersions/suspensions), the viscosity of which can be altered by means of an electric or a magnetic field, and which can also be described as electro-rheological resp. magneto-rheological liquids, are known per se and for example are distributed by Fludicon GmbH, Landwehrstraβe 50, 64293 Darmstadt, Germany. Furthermore, other suitable liquids or media are described among others within EP 0 845 790 A1 and U.S. Pat. No. 4,992,190, EP 0 406 692, JP 41 98 297 and U.S. Pat. No. 5,354,488.  
         [0017]     The hose sections  18 ′ are provided with electrodes  19 , which when applying an electrical voltage generate an electrical field in the corresponding hose section  18 ′. The electrodes  19  at the hose sections  18 ′ are connected with triggering electronic means  20  which are dependent on the signal of one or several sensors  21  and control the voltage applied between the electrodes  19 , and thus the viscosity of the attenuating liquid flowing through the hose section  18 ′, so that by means of the triggering electronic means  20 , the throttle effect within sections  18 ′ is controlled dependent on the signal of at least one sensor  21 .  
         [0018]     In detail, the construction shown is designed so that when a ball hits an area of the racket surface and in view of the increased mechanical tension within the strings  4  at this location, the supporting profile  8  under elastic deformation of the profile section  9  is moved towards the frame profile  2 ′ and in this way attenuating liquid is displaced from that part of the attenuating elements  17 , as shown in  FIG. 3  by arrows K. The displaced attenuating liquid then is distributed across the remaining length of the corresponding attenuating element by elastically deforming the corresponding hose  18 , and flows through a hose section  18 ′ acting as a throttle. Depending on the voltage applied to the electrodes  19  and the change effected thereby, the viscosity of the attenuating liquid acts upon the corresponding hose section  18 ′ more or less as a throttle so that the characteristics of the tennis racket  1  can be dynamically controlled dependent on the signal of the at least one sensor  21 .  
         [0019]     Preferably, several sensors  21  are provided, for example, in such a way that when a ball hits an are of the racket surface in this area, or in other areas of the racket surface, the attenuation effect on the racket is increased by increasing the viscosity of the attentuating liquid, or vice versa the attenuation effect is reduced by reducing the viscosity of the attenuating liquid.  
         [0020]     The sensor(s)  21  preferably are sensors operating according to the piezo effect, which are dependent on the deformation of the frame profile  2 ′ or the support profile  8  produces an electric signal. Said sensors then are provided accordingly, at the frame profile  2 ′, or at a support profile  8 . Contrary thereto, the sensor(s)  21  can be designed so that the deformation of the support profile  8 , relative to the tension frame profile  2 ′, can be determined and a signal can be delivered, which is dependent therefrom. Other types of sensors  21  can be used, too.  
         [0021]     The sensor(s)  21 , moreover, can be arranged on the racket handle, or between the racket handle  7  and the racket head in such a manner that the signal generated by said sensors is dependent on the deformation or torsion of the racket frame or the racket core  5 .  
         [0022]     Basically, it is possible to trigger the pairs of electrodes  19  provided on the hose sections  18 ′ individually or in groups by the control means  20 , namely by signals of one or several sensors, for example by using available triggering patterns determined within the electronic means  20  or the memories thereof.  
         [0023]     Furthermore, it is possible to provide adjustment means instead of the sensor  21  or in addition thereto, by means of which the attenuating action or stiffness of the damping elements  17  can be adjusted manually.  
         [0024]     The electronic means  20 , the required voltage supply, in the form of at least one battery, preferably a reloadable battery, and the adjustment means  22  and also the indication means  23 , giving information concerning the condition of the system can be arranged, within the racket handle  7 .  
         [0025]     Above, there has been described that influencing the viscosity of the attenuating liquid is performed by means of an electric field. Basically, there is also the possibility to use a magnetic field instead of an electric field for acting upon the attenuating liquid. In this case, for example, at the hose sections  18 ′ instead of electrodes  19  at least one magnetic coil each is used, which embraces the corresponding section  18 ′ and which is triggered by the control means  20 .  
         [0026]     Above, there has also been described that the attenuating elements  17  are hoses. Generally, there is the possibility to provide individual, closed, for example cushion-type elements which are filled with an attenuating liquid the viscosity of which is controlled by means of an electric or a magnetic field.  
         [0027]     Contrary to the described structure, there is also the possibility to provide chambers or closed spaces for receiving the liquid altering the viscosity within the racket or racket head frame in such a manner that any deformation of the racket frame or racket head frame results in a flow of said liquid. By altering the viscosity of the liquid the flow thereof can be promoted in a controlled manner or can be reduced so that then the deformability of the racket head frame or the racket frame altogether can be controlled.  
         [0028]      FIG. 4  shows again the tension frame profile  2 ′ and one of the strings  4 , which reaches through the tension frame profile and abuts against a string supporting element  24  (Osenband) at the periphery of the tension frame  2 . A two-piece sensor  21  is arranged inbetween the string supporting elemetns  24  and the tension frame  2 . This string  4  runs in between a tension frame area A neighbored the core  5  or core element  5 ″ and a tension frame area B which is opposite the tension frame area A in the driection of the longitidunal axis of the handle element  7 .  
         [0029]     A sensor  21  is provided at each of these areas A, as is shown in  FIG. 4 . The attenuating elements are each formed by a hose-type or cushion-type element with a closed interior for the attenuating liquid provided on the side areas of the tension frame in between the areas A and B, meaning on the tension frame areas C and D between the frame profile  2 ′ and the support profile B, as shown in  FIG. 2 .  
         [0030]     The invention has been described in connection with various embodiments. The expert realizes that numerous further alterations and revisions will be possible without leaving the scope of invention.  
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           1  tennis racket  
           2  tension frame  
           2 ′ tension frame profile  
           3  stringing  
           4  string  
           4 ′ string length  
           5  core  
           5 ′ arm  
           6  handle shaft  
           7  racket handle  
           8  support profile  
           9  profile section  
           10 ,  11  recess  
           12  eyelet  
           13 ,  14  bore  
           15  bore  
           16  recess  
           17  attenuating element  
           18  hose  
           18 ′,  18 ″ hose section  
           19  electrode  
           20  control electronic means  
           21  pressure sensor  
           22  adjustment device  
           23  indication