Patent Abstract:
The spin improvement string pliers is a pivotally secured together plier device used to manually restructure and roughen the surface of a synthetic string on a strung tennis racquet by means of plastic deformation. The line grids on the pliers depress the string, leaving a series of indentations on the string surface that increases the friction between the string and the ball so that the tennis player can more easily generate top or under spin on a tennis ball or a racket ball.

Full Description:
FIELD OF INVENTION 
     The present invention relates to a pivotally secured together plier device used to manually restructure and roughen the surface of a synthetic tennis string on a strung tennis racquet. The roughened string surface increases the friction between the string and the tennis ball and thus the player can more easily generate spin on a tennis ball or a racket ball while striking the ball. 
     BACKGROUND OF THE INVENTION 
     Many tennis players try many different techniques to generate spin when they hit the tennis balls. The spin is generated by friction between the string and the ball. Thus, the rougher the string surface is, the easier it is for the player to generate spin. However, most strings, especially the new synthetic strings, are cylindrical in shape and have a smooth surface, making it difficult for players to generate a high speed spin on the tennis balls. 
     Most strings are made of synthetic fiber and some of them are made of natural gut. Some string manufacturers provide Octagon or Hexagon shaped strings to increase the friction between the string and ball. It may be effective on the main string, but it does not make any difference on the cross string because of the direction of the racquet swing movement. In addition, after some time, the sharp edge of the Octagon and Hexagon will be worn away by wear and tear between the string and ball. Some strings come with a series of small dents on the surface to increase the roughness of the string surface. This is effective when it is new, however, after some time, the small dents will be worn off and the string surface becomes smooth again. 
     Even though the above mentioned non-cylindrical strings are commercially available, they can be expensive and/or lose some other good quality characteristics compared to traditional cylindrical shaped strings. Cylindrical shaped strings are still the most commonly used strings. 
     BRIEF SUMMARY OF THE INVENTION 
     The primary objective of this invention is to provide a plier device to mechanically and permanently restructure the surface of a tennis racquet string, section by section on a strung tennis racquet, by means of mechanical deformation on a string. 
     In accordance with the present invention, there is provided a plier device comprising a pair of handle levers including a middle portion pivotally secured together with a pivot shaft. Each lever has a handle on one end and a jaw on the other. The plier device is made of steel or another hard material. Both upper jaw and bottom jaw have an elevated pattern of closely adjacent line grids. The end of the bottom jaw has an “L” shaped string locker design with a slot in the middle, which allows the bottom jaw to slide beneath a string by rotating the plier handles. Once the upper jaw is above the string and bottom jaw is beneath the string, close the pliers. A series of elevated line grids will then press and reform the string surface and leave a series of indentations on the string without damaging other characteristics of the string. The roughened string surface increases friction between the string and ball, making it easier for the players to generate spin. After some time, if the indentations on the string are removed because of wear and tear, the pliers can be used again to roughen the string. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the string pliers in accordance with the present invention. 
         FIG. 2  is another exploded view of the string pliers in accordance with the present invention. 
         FIG. 3  is a close up exploded view of the bottom jaw when the pliers are open. 
         FIG. 4  is a close up exploded view of the upper jaw when the pliers are open. 
         FIG. 5  is a front view of the string pliers when they are closed. 
         FIG. 6  is a front view of the string pliers when they are open. 
         FIG. 7  is an exploded view of step  1  of how to use the string pliers on a strung racquet. 
         FIG. 8  is an exploded view of step  2  of how to use the string pliers on a strung racquet. 
         FIG. 9  is an exploded close up view of step  1  of how to use the string pliers on a strung racquet. 
         FIG. 10  is an exploded close up view of step  2  of how to use the string pliers on a strung racquet. 
         FIG. 11  is a close up front view of the tennis string before string pliers are used. 
         FIG. 12  is a close up back view of string before string pliers are used. 
         FIG. 13  is a close up front view of string after string pliers are used. 
         FIG. 14  is a close up back view of string after string pliers are used. 
         FIG. 15  is an exploded view of the two combined string pliers in accordance with the present invention. 
         FIG. 16  is another exploded view of the two combined string pliers in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1  and  FIG. 2 , the tool of the present invention can be seen to include two plier handles  10 - 10  which pivot about pivot pin  11 . One of the handles  10 - 10  is rigidly connected to upper jaw  22  and the other handle is rigidly connected to lower jaw  21 . When handles  10 - 10  are spread apart, the jaws open, as shown in  FIG. 1 ,  FIG. 2  and  FIG. 6 , and when the handles  10 - 10  are closed, the jaws close, as indicated in  FIG. 5 . Upper jaw  22  and lower jaw  21  contain an elevated pattern of adjacent line grids  18  and  19 , as indicated in  FIG. 3  and  FIG. 4 . The line grids  18  and  19  can come with different shapes, a rectangular block, a pyramid, a triangle or a half cylinder. 
     The upper jaw  22  and lower jaw  21  are shown in greater detail in  FIG. 3  and  FIG. 4 . The upper jaw  22  has an elevated L shaped jaw tip  25  at the end. An elevated pattern of elements  18  is on the top of elevated L shaped jaw tip  25 . Right beneath the elevated L shaped jaw tip  25  on the upper jaw  22 , a recessed indentation  24  is located on the lower jaw  21 . The indentation  24  is about ⅛″-½″ wide and 3/16″ to 5/16″ deep. An elevated pattern of line grids  19  is on the top of the recessed indentation  24 , as indicated in  FIG. 3 . The recessed indentation  24  is to lock the string in place once the lower jaw  21  slides beneath the string. Upon closure of the upper jaw  22  and the lower jaw  21 , a gap  12  is formed between line grids on the upper jaw  22  and the lower jaw  21 , as indicated in  FIG. 5 . The formed gap  12  is about 1/32″ which prevents the string from being cut by the elevated line grids  18  and  19  on the upper jaw  22  and lower jaw  21  respectively. 
     The lower jaw  21  has 2 elevated L shaped string lockers  23  at the end, which are extruded from upper jaw  22 , as indicated on  FIG. 5 . Between these two L shaped string lockers  23 , at the end of lower jaw  21 , a slot  16  about ⅛″ in width and ½″ in depth is located in the center. 
     In  FIG. 3  and  FIG. 4 , it can be seen that the center lines of the elevated pattern line grids  18  and  19  are not parallel to the center lines of the upper jaw  21  and lower jaw  22 . Instead, these two lines form an angle A 1 . Angle A 1  indicated in  FIG. 3  and  FIG. 4  may vary from about 15° to about 30°, or more preferably from about 20° to 25°. This feature allows the string pliers to make indentation marks on the strings that are not vertical or parallel to the center line of the main or cross strings. This design makes it easier for tennis players to generate spin on the balls. 
     In  FIG. 5 , it can be seen that the center line of upper jaw  22  and bottom jaw  21  is not parallel to the center line of the handles  10  of the pliers. Instead, it forms an angle A 2 . This feature makes the tool of the present invention much easier to operate than if it had the center line of upper jaw  22  and lower jaw  21  in direct alignment with the center line of the plier handles  10 . Angle A 2  indicated in  FIG. 5  may vary from about 15° to about 35°, or more preferably from about 20° to 25°. 
     The manner in which the tool of the present invention is used to deform and roughen the surface of the string on a strung racquet is shown in  FIG. 7-12 . In  FIG. 7 , the player intends to make a series of indentations on a cross string  14  on a strung racquet  13 . The player first puts the elevated L shaped string lockers  23  located at the end of lower jaw  21  under the cross string  14 , while the main string  15  is inserted in the slot  16  located in the center of lower jaw  21 . The L shaped string lockers  23  and the slot  16  lock both the main string  15  and the cross string  14  in place. This step is shown in greater detail in  FIG. 9 . The player then pushes down the plier handles  10 , so the plier pivots about the cross string  14 , As a result, the main string  15  is pushed down by the slot  16  and the lower jaw  21  is pushed under the cross string  14 . Cross string  14  is then pushed on the recessed indentation  24  on lower jaw  21 , and indentation  24  locks the cross string  14  in place, as indicated in  FIG. 8  and  FIG. 10 . Finally, the player can close the pliers and leave a series of indentations on the cross string  14 , as indicated in  FIG. 11-14 .  FIG. 11  and  FIG. 12  show the front and the back of cross string  14  before the pliers are used.  FIG. 13  and  FIG. 14  show the front and the back of cross string  14  after the pliers are used to depress the cross string  14 . After the string is pressed, the pliers can then be opened and rotated upward to release the cross string  14  and main string  15 . 
     The same manner can be repeated to put a series of indentations on the rest of the cross string  14  and the main string  15 . The player needs to turn over the racquet and work on the other side of the racquet to complete roughening the string surface. It is not necessary to roughen all the strings on the racquet, it is sufficient to roughen the string in the “sweet spot”, where the string makes contact with the balls most often. This covers about ½ the racquet area, in the center. 
     Referring to  FIG. 15  and  FIG. 16 , the pliers can be further modified so twice as much string can be depressed by the pliers at one time. The modification in general is to combine two upper jaws  22  and two lower jaws  21  together, and separate each pair of upper jaw  22  and lower jaw  21  with a long slot  26 . The slot  26  is about ⅛″ wide and 1″ in depth. When cross string  14  is being depressed, both slots  24  allow 2 main strings  15  to be inserted and slot  26  allows one main string  15  to be inserted. Slots  24  push down two main strings  15 , while slot  26  does not push down the main string  15 . 
     The tool of the present invention is made from any suitable common metal such as steel alloy, aluminum alloy, and the like. The handles  10 - 10  of the tool may preferably be covered with an insulator such as plastic, or the like. 
     Although a preferred embodiment of the invention has been disclosed for the purpose of illustration, it will be understood that various changes, modifications, and substitutions may be incorporated in such embodiment within the scope of the invention without departing from the spirit of this invention.

Technology Classification (CPC): 1