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The present invention relates to sports racquets used in playing games such as tennis, racquetball, and other similar games, and more particularly to a novel means of converting a conventional racquet frame have a single plane of playing surface strings into a “double-strung” racquet having two generally parallel planes of playing surface strings.
The conventional racquets used today to play games such as tennis, racquetball, and other racquet similar games, consist of a frame that contains a handle used by the player to hold the racquet and an elliptical or oval shaped head section of the frame used to support the playing surface. The playing surface is formed by the opposite sides of a single set of interwoven strings in tension that pass through holes in the opposing sides of the frame forming a single plane playing surface that spans the opening bounded by the head of the frame. Conventional racquets are therefore “single-strung” with a single plane playing surface consisting of strings in tension passing through a single set of holes in the head of the frame.
Previous proposals have replaced the single plane of interwoven strings that form the playing surface with two generally parallel planes of interwoven strings separated by various distances up to the thickness of the head frame portion of the racquet. A racquet “double-strung” with two separate playing surfaces possesses advantages over the “single-strung” racquet. Some of these advantages are the subject of U.S. Pat. No. 4,049,269 and U.S. Pat. No. 4,204,680. Additional advantages are the ability to incorporate different string types and different string tension values for each of the two separate planes of strings. By so doing, the playing characteristics of each plane can be varied so as to best suit the individual players forehand play that utilizes one of the two planes of strings, and the players backhand play that utilizes the other plane of strings. One playing plane of strings can also be optimized for power while the other is optimized for control. Since the two planes can be made to have different characterizes and harmonics, a dampening of the vibration transmitted to the player's hand and arm upon the racquet coming in contact with the ball or other playing object can also be achieved.
None of the embodiments to date of a “double-strung” racquet utilize a conventional “single-strung” racquet frame. Instead, all embodiments to date of a “double-strung” racquet have incorporated a racquet frame and racquet frame head specifically designed to accommodate the two separate planes of interwoven strings.
Examples of such prior art include U.S. Pat. No. 4,049,269 wherein the racquet head is comprised of a structural marginal frame with an elongated member containing a plurality of stringing receiving apertures; U.S. Pat. Nos. 4,204,680 and 4,320,900 wherein the racquet head contains a “D” channel around the outer periphery with holes perpendicular to the string planes; U.S. Pat. No. 5,322,279 wherein the racquet head contains an outwardly facing stringing groove and a series of stringing holes for each of the two string planes; U.S. Pat. No. 5,423,532 wherein the racquet head contains two rows of holes around the outside peripheral edge of the frame; and U.S. Pat. Nos. 5,743,822 and 6,254,499 wherein the outside peripheral edge of the racquet head contains a continuous side groove and slots about which the string is anchored.
Furthermore, in addition to requiring a non-conventional frame that is specifically designed to accommodate the two separate planes of interwoven strings, the previous attempts to provide a “double-strung” racquet use channels, grooves, or double rows of holes drilled or built into the frame head that affect its structural integrity. It is therefore best to have a method of double stringing a sports racquet that utilizes an unmodified conventional frame so that any racquet can be converted to a “double-strung” racquet without the structural integrity of the frame being adversely affected. This method also provides the ability to convert any racquet frame back and forth between a “single-strung” and “double-strung” configuration.
The present invention is an improved method of “double-stringing” a sports racquet so as to have two generally parallel planes of playing surface strings. The requirement of the above prior art to have a specialized racquet frame with a head specifically designed to accept the two string playing surfaces, is eliminated. Thus, by using any conventional frame without additional holes, groves, or channels, the structural integrality and strength of the frame is not compromised. In addition, since no special frame is required, with the present invention, any sports racquet frame can be converted to a “double-strung” configuration and then converted back to a “single-string” configuration, as desired.
Rather than requiring a specifically designed or modified sports racquet frame, the present invention uses a conversion and playing surface separation ring (hereinafter “conversion ring”) to “double-string” any conventional sports racquet. The conversion ring itself can be made of any rigid or semi-rigid material such as wood, plastic, metal, rubber or composite material. The shape of the ring approximates the shape of the racquet head, but is of a smaller overall dimension. This smaller dimension permits the conversion ring to fit within the racquet head and leaves a small area between the inside dimension of the racquet head frame and the outside dimension of the conversion ring. The racquet is then strung in a convention manner with one set of interwoven strings on each side of the conversion ring. The width or thickness of the vertical surface of the conversion ring determines the separation between the two parallel planes of strings. The space between the frame head and the conversion ring permits the strings that pass over each side of the conversion ring to converge into the single ring of opposing holes in the conventional racquet frame head.
A further embodiment of this invention has a modified shape such that the top vertical edge of the conversion ring that corresponds to the head of the racquet frame and the bottom vertical edge of the conversion ring that corresponds to the throat of the racquet frame are a further distance from the racquet frame than the other vertical edges of the conversion ring to permit the mounting posts and brackets of a sports racquet stringing machine to hold the racquet frame during stringing without interference from the conversion ring.
FIG. 1 is a front view of a conventional sports racquet strung with a single playing field of interwoven horizontal and vertical strings.
FIG. 2 is a cross-sectional view of the head portion of a “single-strung” conventional sports racquet frame.
FIG. 3 is a front view of the present invention conversion ring.
FIG. 4 is a front view of a conventional sports racquet with the present invention conversion ring in place within the head portion of the racquet frame.
FIG. 5 is a front view of a conventional sports racquet that is “double-strung” using the present invention conversion ring.
FIG. 6 is a cross-sectional view of the head portion of a “double-strung” conventional sports racquet frame using the present invention conversion ring.
FIG. 7 is a front view of the present invention conversion ring with modified shape to assist in mounting the sports racquet frame and conversion ring during the stringing process using the mounting posts and brackets common to many sports racquet stringing machines.
FIG. 8 is an angled view of the same modified conversion ring depicted in FIG. 7.
FIG. 9 is a front view of a conventional sports racquet that is “double-strung” using the present invention conversion ring with protrusions added to increase the structural strength of the head frame.
A detailed description of the invention is now provided, with reference to FIGS. 1-9.
Referring to FIG. 1, the conventional sports racquet used today in playing tennis, racquetball, and other similar games, is comprised of a frame 10, constructed of wood, metal, fiberglass, carbon fiber, graphite, or other suitable materials; a head portion 11; a pair of converging throat frame members 12 and 13; and a handle 14 with a covering that assists the player in gripping the racquet. The head 11 portion of the frame is generally elliptical or oval in shape. The head 11 portion supports tensioned strings that are strung in an interwoven pattern of horizontal 15 and vertical 16 string segments. Together, the plurality of these horizontal 15 and vertical 16 strings comprise the single playing plane 17. The interwoven strings pass from the inside diameters 8 to the outside diameter 19 of the head 11 frame through a series of opposing holes in the frame. The interwoven strings then pass back through the frame from the outside 19 diameter to the inside diameter 18 at the adjacent hole until the playing plane 17 is complete.
FIG. 2 is a cross section of the head 11 portion showing a general example of the opposing holes 20 and 21 through which a horizontal string 15 passes from the inside diameter 18 to the outside diameter 19 of the head 11 portion of the frame. The plurality of these horizontal 15 strings together with the plurality vertical strings comprising the single playing plane 17 of a conventional sports racquet.
FIG. 3 depicts the preferred embodiment of the present invention. It consists of conversion ring 30 that can be made out of any rigid or semi-rigid material such as wood, plastic, metal, rubber, or composite material. The conversion ring has a horizontal surface 31 and a vertical surface (not depicted in FIG. 3) which is determined by the thickness of the ring itself. There is also an inside diameter 32 and an outside diameter 33.
FIG. 4 shows the conversion ring 30 in position within the head 11 portion of the sports racquet frame 10. The outside diameter 33 of the conversion ring 30 is smaller than the inside diameter 18 of the head portion 11 of the frame. While the ring can be of any circular, rectangular, polygonal, oval or elliptical shape, the preferred embodiment is for the conversion ring 30 to be of generally the same shape as the head portion of the racquet frame with which it is to be used so as to yield a uniform or nearly uniform space 40 between the head portion 11 of the frame and the conversion ring 30 when they are placed in generally the same horizontal plane with the conversion ring 30 within the opening of the head portion 11.
With the conversion ring 30 in the position as depicted in FIG. 4, the sports racquet frame 10 can then be strung in any conventional manner twice, once on each side of the conversion ring. This space 40 between the head portion 111 of the frame and the conversion ring 30, permits the strings that pass over each side of the conversion ring to converge into the same single hole used for conventional “single-stringing”. As illustrated in FIG. 5, this “double-stringing” produces two separate playing planes 17 instead of the conventional single playing plane 17. One on the forward facing side of the conversion ring 30 as it is depicted in FIG. 5, the forward facing playing field 50; and one on the rearward facing side of the conversion ring 30; the rearward facing playing field 51.
FIG. 6 is a cross section of the head 11 portion “double-strung” with the conversion ring 30 in place. The forward facing playing field 50 and the rearward facing playing field 51 are in parallel planes to each other separated by a distance 60 determined by the thickness or vertical dimension 61 of the conversion ring 30. This vertical dimension 61 and resultant separation between the two planes can differ from conversion ring to conversion ring so to produce the desired playing characteristics for the racquet. Similarly, different materials can be used in the conversion ring 30 to alter the playing characteristics and the dampening affect the ring has on the vibration of the strings and racquet frame.
In addition, the conversion ring 30 permits each of the two playing fields to be strung with different types of strings and at different tensions. Since it is normal when playing tennis and other similar games to use one side of the racquet frame to hit the ball or other playing object for forehand strokes and the reverse side of the racquet for backhand strokes, the present invention also enables the played to alter the playing characteristics of the playing field on each side of the racquet so as to have one playing field best suited to the player's forehand and the other playing field best suited to the player's backhand.
FIG. 6 also shows that by using the conversion ring 30, the two strings making up the two separate playing fields (50 and 51), can pass through the same opposing holes 20 and 21, in the racquet head 11 portion of the frame, used for conventional “single-stringing”. And, since no alteration to the racquet frame itself is required, the present invention permits the conversion of any conventional racquet frame into a “dual-strung” racquet. Similarly, a racquet “dual-strung” using the present invention, can also be easily converted back to its “single-strung” configuration.
A further embodiment of the invention is depicted in FIG. 7 and FIG. 8. In FIG. 7, the conversion ring 30 in modified in shape so that the top vertical edge 70 of the ring and the bottom vertical edge 71 of the conversion ring are a further distance from the head portion of the frame. This added distance, and resulting space between the conversion ring and the head portion of the frame, permits the mounting posts and brackets common to many sports racquet stringing machines to easily pass between the frame and the conversion ring without interference so as to securely hold the racquet frame during the stringing process. FIG. 8 is an angled view of the same modified conversion ring depicted in FIG. 7. FIG. 8 also shows the thickness or vertical dimension 61 of the conversion ring that separates the two playing fields. As described above, this dimension can be varied to produce different playing characteristics.
Another embodiment of the invention is depicted in FIG. 9. In FIG. 9 the conversion ring 30 is constructed so as to have one or more protrusions 90 on the outside diameter 33 of the conversion ring. These protrusions 90 are of such a dimension so as to make the conversion ring 30 come into contact with the frame head 11 portion of the frame at those locations. By so doing, the structure of the conversion ring 30 helps counteract the inward forces placed on the head 11 portion of the frame by the tension of the strings. And, since the protrusions are located between the holes in the head 11 portion of the frame, they do not interfere with the strings of either playing surface or the stringing process.
In addition to the above embodiments of the conversion ring, said conversion ring can also have distinctive marks, colors and/or labeling on each of its two horizontal surfaces thereby distinguishing one side on the conversion ring from the other side of the conversion ring. Since the playing surface on each side of the conversion ring can be made to have different playing characteristics due to different strings and string tensions, such marking or coloring on the conversion ring will enable the user of the racquet to visually differentiate between the two playing surfaces.
The foregoing represents a preferred embodiment of the invention. Variations and modifications will be apparent to persons skilled in the art, without departing from the inventive concepts disclosed herein. All such modifications and variations are intended to be within the skill of the art, as defined in the following claims.