Abstract:
A device and method for determining whether or not the string face of a racket is held in a vertical plane as the racket is swung. At least one sensor is attached to a racket. The sensors detect when the string face of the racket is in a vertical plane and when the string face deviates from that vertical plane. An indicator is also attached to the racket, wherein the indicator produces a perceivable indication to the user of the racket wher activated. A logic circuit is used to connect the sensors to the indicator. When the sensors detect that the string face of the racket has wandered from the vertical plane, the indicator is activated and the player holding the racket is informed of the lapse in form. By repeatedly swinging the racket and trying to avoid activating the indicator, a player can train to have a proper level swing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to rackets that are used in sports activities such as tennis, squash, badminton and the like. More particularly, the present invention relates to electronic devices that are integrated into such rackets, or attachable to such rackets, that help a person train to properly use those rackets.  
           [0003]    2. Description of the Prior Art  
           [0004]    There are many sports that are played with a racket. One of the most popular of these sports is tennis. In the game of tennis, the racket includes an oblong head section supported by a handle. A string is strung back and forth through the head section of the racket, thereby producing a mesh structure that is known as the string face of the racket. The string face of the racket is the surface of the racket that is used in the game to contact the ball.  
           [0005]    The string face of the racket extends in a single plane. During play, it is the orientation of the plane of the string face that mostly determines the direction of a ball or other projectile struck by the racket.  
           [0006]    In the game of tennis, players are taught to hold the tennis racket in their hands so that the plane of the string face extends vertically. This vertical orientation of the string face should be maintained as the racket is swung and contacts the tennis ball. Presently, a determination of whether or not a racket&#39;s string face is held vertically as it contacts a ball can only be determined from the trajectory of the ball after the ball leaves the string face. If a ball, having a level trajectory prior to striking the string face of the racket, has either an ascending or descending trajectory after impacting the string face, then it can be determined that the string face was not vertical at the time of impact. Accordingly, the ability of a person to practice holding a racket vertically when swinging the racket could formally be done only by actually striking a ball. Consequently, practice time was limited to the time a player actually spends on a court striking balls.  
           [0007]    A need therefore exists for a device that can help a person determine if they are holding the string face of a racket vertically during a swing without having to strike a ball. As such, a person can practice their racket swing in any location and at any time. This need is met by the present invention as described and claimed below.  
         SUMMARY Of THE INVENTION  
         [0008]    The present invention is a device and method for determining whether or not the string face of a racket is held in a vertical plane as the racket is swung. At least one sensor is attached to a racket, either retroactively, or at the time of the racket&#39;s manufacture. The sensors detect when the string face of the racket is in a vertical plane and when the string face deviates from that vertical plane. An indicator is also attached to the racket, wherein the indicator produces a perceivable indication to the user of the racket when activated. A logic circuit is used to connect the sensors to the indicator. When the sensors detect that the string face of the racket has wandered from the vertical plane, the indicator is activated and the player holding the racket is informed of the lapse in form. By repeatedly swinging the racket and trying to avoid activating the indicator, a player can train to have a proper level swing.  
           [0009]    Other sensors may be present that detect when the racket has contacted a ball or when the racket is being used to serve a ball. These sensors, either activate or deactivate the normal functioning of the indicator to prevent the indicator from producing false error indications. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    For a better understanding of the present invention, reference is made to the following description of exemplary embodiments thereof, considered in conjunction with the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 is a side view of a first exemplary embodiment of a tennis racket in accordance with the present invention;  
         [0012]    [0012]FIG. 2 is a schematic block diagram illustrating the electronic components of a simple version of the present invention; and  
         [0013]    [0013]FIG. 3 is a schematic block diagram illustrating the electronic components of a complex version of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    Although the present invention device can be used in association with any strung racket, such as a racquetball racket, a squash racket, a badminton racket or the like, the present invention device is particularly well suited for use as a tennis racket. Accordingly, the exemplary embodiment of the present invention will be described as a tennis racket in order to set forth the best mode contemplated for the invention. However, it will be understood that any other type of racket can be substituted for the tennis racket described.  
         [0015]    Referring to FIG. 1, a tennis racket  10  is shown in accordance with the present invention. The tennis racket  10  has a handle  12 , an enlarged head  14  and a neck region  16  where there is a transition between the handle  12  and the enlarged head  14 . A string face  20  is strung within the confines of the enlarged head  14 , wherein the string face  20  lays in a flat plane.  
         [0016]    The tennis racket  10  has an imaginary centerline  22  that extends down the center of the racket  10 . The handle  12  of the racket  10 , the enlarged head  14  of the racket  10  and its string face  20  are all symmetrically disposed around the centerline  22 .  
         [0017]    In the game of tennis, it is desirable to keep the string face  20  of the racket  10  in a vertical plane during many types of swings. It is especially important to hold the string face  20  of the racket  10  vertically during a swing at the point of contact with a tennis ball. Using the imaginary centerline  22  of the tennis racket  10  as a reference, it can be seen that when the string face  20  of the racket  10  is vertical, the string face  20  extends vertically both above and below the centerline  22 . However, when the string face  20  of the racket  10  is not vertical, it means that the racket  10  has been turned about the centerline  22  in one of the directions of rotation arrows  24 . As such, the string face  20  of the racket  10  extends above and below the centerline  22  at complementary angles.  
         [0018]    An electronic assembly  30  is affixed to the racket  10  in the neck region  16  of the racket  10 . The electronic assembly  30  contains at least one sensor that detects when the string face  20  of the racket  10  is in a vertical plane and when it is not. If the string face  20  of the tennis racket  10  is sensed to be not vertical, the electronic assembly  30  produces an audible tone that can be heard by the player holding the racket  10 . As such, by listening to the audible signal, a player can tell if the string face  20  of the racket  10  is being held vertically during a swing. By adjusting the racket  10  in response to the audible signals, a player can correct his/her swing so that the swing keeps the string face  20  of the racket  10  vertical.  
         [0019]    Furthermore, the audible signals generated by the racket  10  can be produced during any swing, whether or not the swing produces contact with a ball. Consequently, a person can practice swinging the racket  10  without having to strike a ball and the racket  10  will provide an indication as to whether or not the racket string face  20  was held vertically throughout the swing. A tennis swing can therefore be practiced at any time, in a confined space, without need of a ball.  
         [0020]    From the embodiment of FIG. 1, it can be seen that the electronic assembly  30  is preferably positioned in the neck section  16  of the racket  10 , in between the handle  12  and the enlarged head  14 . The electronic assembly  30  can be manufactured as part of the racket  10 , or can be retroactively added to the racket  10 . On the exterior of the electronic assembly  30  is a speaker port  32  and an on/off switch  34 . Optional adjustment controls  36  can be present depending upon the embodiment of the present invention used.  
         [0021]    Referring to FIG. 2, a schematic for a simple embodiment of the present invention is shown. In this embodiment, audible tones are broadcast aloud by a speaker  40 . A tone generator  42  produces the tones broadcast by the speaker  40 . The tone generator  42  is capable of producing a plurality of distinct tones that are readily discernable by a person holding the tennis racket. A volume control  44  is provided, so that a player can adjust the volume of the tones according to the needs of the tennis player in light of the surrounding ambient noise.  
         [0022]    Within the electronic assembly  30  are sensors  46 . The sensors  46  are oriented with respect to the tennis racket so that the sensors  46  detect when the string face  20  (FIG. 1) of the racket is tilted out of a vertical plane. In the embodiment of FIG. 2, multiple sensors  46  are used. Each sensor  46  has a different degree of sensitivity. Accordingly, if the string face of the racket is tilted only slightly out of the vertical, only one of the sensors  46  will detect the deviation. However, as the degree of deviation from the vertical increases, subsequent sensors  46  will detect the increasing deviation.  
         [0023]    The sensors are coupled to a logic circuit  48 . The logic circuit  48  directs the tone generator  42 , thereby instructing the tone generator  42  to produce a tone. Depending upon the degree of deviation from vertical and the number of sensors  46  activated, the logic circuit  48  instructs the tone generator  42  to produce different tones. For example, if the string face  20  (FIG. 1) is titled only a few degrees from vertical, only one highly sensitive sensor may detect the deviation. The sensor signal is read by the logic circuit  48  and activates the tone generator  42  to produce a first tone. If the angle of deviation from vertical increases, a medium sensitivity sensor detects the angle and the logic circuit  48  activates the tone generator  42  to produce a second tone. In the same manner, the tone generated is changed as the string face experiences different angles of inclination and different combinations of the sensors  46  are activated.  
         [0024]    Accordingly, when the string face  20  (FIG. 1) of the tennis racket is vertical, no audible indication is produced. However, as the string face of the racket is tilted out of the vertical, an audible tone is produced that varies with the angle of inclination experienced by the string face. Accordingly, as a tennis player swings the tennis racket, the player will be able to hear when the string face of the racket moves out of the vertical plane. By the tone generated, the tennis player will also be able to hear a signal that tells the player how far from the vertical the string face was moved. Furthermore, by listening to the generated tones and adjusting the racket during the swing, a player can practice perfecting their swing so that there is little deviation of the string face during the swing.  
         [0025]    In the embodiment of FIG. 2, a plurality of different sensors  46  are used to detect various degrees of deviation of the string face from the vertical plane. The use of multiple sensors  46  is merely exemplary and it should be understood that only a single sensor need be used. Single tilt sensors do exist that produce an analog output that is dependent upon the angle of inclination experienced. Any such sensor can be used. Similarly, a simple tilt senor that produces only one signal when tilted beyond a threshold angle of inclination can also be used in an inexpensive, simple embodiment of the present invention.  
         [0026]    In the game of tennis, there are times when the string face of the racket is purposely moved out of the vertical plane, for example, during an overhead lob or an overhead serve. Also, due to differences in the ability and size of people who play tennis, not everyone does have, or should have, a perfectly level swing throughout their entire swing. Rather, they have swings that hold the string face level primarily just before, during and immediately after contact with the ball.  
         [0027]    Referring to FIG. 3, a schematic of a more complex embodiment of the present invention is shown. Since the schematic of FIG. 3 shares many components with the schematic of FIG. 2, like parts share the same reference numbers in order to reduce confusion. In the embodiment of FIG. 3, there is at least one sensor  46  that detects when the string face of the racket is turned out of a vertical plane. The sensors  46  are read by a logic circuit  48 , that directs a tone generator  42  to create tones. This method of operation is the same as was previously described with regard to the embodiment of FIG. 2. What differs about the embodiment of FIG. 3, is the addition of two more sensors. One sensor is a handle orientation sensor  52 . The handle orientation sensor  52  detects when the handle  12  (FIG. 1) of the racket is held vertically up, as during the height of a serve, or vertically down, as during a lob shot. In such orientations, the handle orientation sensor  52  produces a signal that instructs the logic circuit  48  to not activate the tone generator  42  regardless of the angle of inclination of the racket&#39;s string face. Accordingly, a tennis player will not have to be distracted with tones during a serve.  
         [0028]    In the embodiment of FIG. 3, an impact sensor  50  is also present. The impact sensor  50  is an accelerometer that can sense the impact of when the string face of the racket comes in contact with a ball. The logic circuit  48  can be configured so that it is capable of activating the tone generator  42  only during and immediately following the impact sensor  50  detecting contact with the ball. Accordingly, the tone generator  42  will only generate a tone as the string face of the racket contacts a ball. If the string face of the racket is vertical at the time of impact, then no tone is generated. If the string face of the racket is not vertical at the time of impact, taken a tone is generated that informs the player of the error. This method of operation enables the present invention to help tennis players who do not have a level swing and are not inclined to change their swing.  
         [0029]    It will be understood that the embodiments of the present invention described and illustrated are merely exemplary and that a person skilled in the art can make numerous modifications and variations to the shown embodiments. For example, the electronic assembly can be contained within the handle of the racket, rather than in the neck region of the racket. The electronic assembly can be either manufactured as part of the racket or selectively attached to an existing racket. All such alternate embodiments are intended to be included in the present invention as claimed below.