Racquet having articulating grommet assemblies

A sports racquet including a frame, at least one grommet assembly. The frame includes a head portion coupled to a handle portion. The head portion includes a hoop having inner and outer peripheral walls. At least a first set of concave recesses and channels are formed into the outer peripheral wall. The hoop includes first, second and third groups of string openings. The second and third groups of string openings are aligned with the first set of concave recesses. The second group of string openings extends through the outer peripheral wall at the first set of concave recesses. The grommet assembly engages the outer peripheral wall. The grommet assembly includes at least three pivotable elements interconnected by torque transmitting arms, each pivotable element including a string passage. The pivotable elements and the torque transmitting arms are pivotable about an axis parallel to a string bed plane.

FIELD OF THE INVENTION

The present invention relates generally to a sports racquet. In particular, the present invention relates to racquet including a head portion having at least one articulating grommet assembly.

BACKGROUND OF THE INVENTION

Sport racquets, such as tennis, racquetball, squash and badminton racquets, are well known and typically include a frame having a head portion coupled to a handle portion. The head portion supports a string bed having a plurality of main string segments interwoven with a plurality of cross string segments. Many racquets also include a throat portion positioned between and connecting the handle portion to the head portion. The typical string bed of a sports racquet includes a central region, that provides the most responsiveness, the greatest power and the best “feel” to the player, upon impact with a ball, and a peripheral region. The central region, commonly referred to as the “sweet spot,” is typically defined as the area of the string bed that produces higher coefficient of restitution (“COR”) values. A higher COR generally directly corresponds to greater power and greater responsiveness.

Generally speaking, the size of the sweet spot of a racquet will increase with increased string segment length. The longer string segments enable the string bed to deflect more when impacting a ball and provide a longer “dwell time” between the string bed and the ball upon impact. The increased “dwell time” improves not only the responsiveness of a racquet, but also its control, including the ability to impart spin on the ball.

Some existing racquets incorporate a larger sized hoop portion supporting a larger sized string bed (i.e., a larger head size) in an effort to increase the size of the string bed and the sweet spot. However, as the head size of a racquet increases, so does the polar moment of inertia of the racquet. A racquet with a higher polar moment of inertia can be more difficult to maneuver, particularly at the net or upon return of serve, than a racquet with a lower moment of inertia. Additionally, some users find large head racquets to be more difficult to swing than racquets with normal sized heads.

Other racquets have incorporated different head shapes in an effort to increase the length of certain main or cross string segments, without increasing the size of all of the main and cross-string segments. Although such designs can provide a more targeted approach to increasing the performance of the racquet, such designs can also result in an undesirable increase in the polar moment of inertia of the racquet. Further, such designs may also result in a head size that has an undesirable appearance, or an appearance that is markedly different from the look and design of traditional sport racquet designs.

Thus, there is a continuing need for a racquet having a string bed with an enlarged sweet spot and providing an increased “dwell time,” without negatively effecting the overall performance of the racquet. It would be advantageous to provide a racquet with an enlarged sweet spot and an increased “dwell time” without increasing the polar moment of inertia of the racquet head and without negatively affecting the maneuverability of the racquet. It would also be advantageous to provide a means for targeting certain main and/or cross string segments in an effort to optimize the performance of a particular racquet design, without increasing the polar moment of inertia of the racquet head and without negatively affecting the maneuverability of the racquet. There is also a need for a racquet having a string bed with an enlarged sweet spot that is not a radical departure in look and design from traditional sport racquet designs.

SUMMARY OF THE INVENTION

The present invention provides a sports racquet for impacting a game ball. The sports racquet includes a frame, at least one grommet assembly and a string bed. The frame includes a head portion coupled to a handle portion. The head portion includes a hoop having inner and outer peripheral walls, at least a first set of concave recesses and a first set of channels formed into the outer peripheral wall. The first set of concave recesses are spaced apart by and interconnected with the first set of channels. The hoop includes first, second and third groups of string openings. The first group of string openings is generally circular and extends through the inner and outer peripheral walls. The second group of string openings extends through the outer peripheral wall at the at least first set of concave recesses. The third group of string openings extends through the inner peripheral wall at locations corresponding to the second group of string openings. The grommet assembly engages the outer peripheral wall. The grommet assembly includes at least three pivotable elements interconnected by torque transmitting arms. Each pivotable element includes a string passage. The string bed is formed of a plurality of cross string segments and a plurality of main string segments, and defines a string bed plane. Each string passage has a cross string segment or a main string segment extending therethrough, whereby upon impact with the ball, one or more cross or main string segments deflect thereby causing a first group of one or more pivotable elements supporting the deflecting cross or main string segments to pivot. The pivotable elements and the torque transmitting arms positioned adjacent to the first group of pivotable elements are pivotable in response to rotation of the first group of pivotable elements.

According to a principal aspect of a preferred form of the invention, a sports racquet for impacting a game ball includes a frame, at least one grommet assembly and a string bed. The frame includes a head portion coupled to a handle portion. The head portion includes a hoop having inner and outer peripheral walls, at least a first set of concave recesses and a first set of channels formed into the outer peripheral wall. The first set of concave recesses are spaced apart by and interconnected with the first set of channels. The hoop includes first, second and third groups of string openings. The first group of string openings is generally circular and extends through the inner and outer peripheral walls. The second group of string openings extends through the outer peripheral wall at the at least first set of concave recesses. The third group of string openings extends through the inner peripheral wall at locations corresponding to the second group of string openings. The grommet assembly engages the outer peripheral wall. The grommet assembly includes at least three pivotable elements interconnected by torque transmitting arms. Each pivotable element includes a string passage. The string bed is formed of a plurality of cross string segments and a plurality of main string segments, and defines a string bed plane. Each string passage has either a cross string segment or a main string segment extending therethrough. The cross or main string segment extending through one of the pivotable elements is deflectable upon impact with the game ball. The deflection of the cross or main string causes the pivotable element supporting the one deflecting cross or main string segment to rotate about an axis parallel to the string bed and to produce a torque on the pivotable elements positioned on opposite sides of the one pivotable element through the torque transmitting arms.

According to another preferred aspect of the invention, a sports racquet for impacting a game ball includes a frame, at least one grommet assembly and a string bed. The frame includes a head portion coupled to a handle portion. The head portion includes a hoop having inner and outer peripheral walls, at least a first set of concave recesses and a first set of channels formed into the outer peripheral wall. The first set of concave recesses are spaced apart by and interconnected with the first set of channels. The at least one grommet assembly engages the outer peripheral wall. The grommet assembly includes at least three pivotable elements interconnected by torque transmitting arms. Each pivotable element includes a string passage. The string bed is formed of a plurality of cross string segments and a plurality of main string segments, and defines a string bed plane. Each string passage has one of the cross string segments and main string segments extending therethrough. Each pivotable element has a first cross-sectional area measured about a first plane that is orthogonal to the string bed and parallel to the string segment extending through the pivotable element. Each torque transmitting arm has a second cross-sectional area measured about a second plane parallel to the first plane. The first cross-sectional area is greater than the second cross-sectional area.

This invention will become more fully understood from the following detailed description, taken in conjunction with the accompanying drawings described herein below, and wherein like reference numerals refer to like parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, a sports racquet is indicated generally at10. The racquet10ofFIG. 1is configured as a tennis racquet, however, the invention can also be formed as other types of sports racquets, such as, for example, a racquetball racquet, a squash racquet, or a badminton racquet. The racquet10includes a frame12and a string bed14. The frame12is a tubular structure having a longitudinal axis16and including a head portion18, a handle portion20, and a throat portion22coupling the head and handle portions18and20. The frame12is formed of a lightweight, durable material, preferably a carbon-fiber composite material. As used herein, the term “composite material” refers to a plurality of fibers impregnated (or permeated throughout) with a resin. The fibers can be co-axially aligned in sheets or layers, braided or weaved in sheets or layers, and/or chopped and randomly dispersed in one or more layers. The composite material may be formed of a single layer or multiple layers comprising a matrix of fibers impregnated with resin. In particularly preferred embodiments, the number layers can range from 3 to 8. In multiple layer constructions, the fibers can be aligned in different directions with respect to the longitudinal axis24, and/or in braids or weaves from layer to layer. The fibers are formed of a high tensile strength material such as graphite. Alternatively, the fibers can be formed of other materials such as, for example, glass, carbon, boron, basalt, carrot, Kevlar®, Spectra®, poly-para-phenylene-2, 6-benzobisoxazole (PBO), hemp and combinations thereof. In one set of preferred embodiments, the resin is preferably a thermosetting resin such as epoxy or polyester resins. In other sets of preferred embodiments, the resin can be a thermoplastic resin. The composite material is typically wrapped about a mandrel and/or a comparable structure, and cured under heat and/or pressure. While curing, the resin is configured to flow and fully disperse and impregnate the matrix of fibers.

Alternatively, the frame12can be formed of other materials including metallic alloys, other composite materials, wood, or combinations thereof. The head portion18forms a distal region24, first and second side regions26and28, and a proximal region30, which collectively define a string bed area32for receiving and supporting the string bed14. In one preferred embodiment, the proximal region30includes a yoke34.

The yoke34is an elongate tubular structural member which extends from the first side region26to the second side region28of the head portion18. In one preferred embodiment, the yoke34is integrally formed with the frame12defining the proximal region30. In alternative preferred embodiments, the yoke34can be connected through use of adhesives, fasteners, bonding and combinations thereof. In another embodiment, the yoke34can separated from the frame12by vibration absorbing material, such as, for example, an elastomer. The yoke34is formed of a lightweight, durable material, preferably a carbon-fiber composite material. Alternatively, the yoke34can be formed of other materials, such as, for example, metallic alloys, other composite materials including basalt fibers, and combinations thereof. The yoke34provides structural support to the frame12, as well as a means for defining the lower portion of the string bed area32and a support for engaging, routing or directing the main string segments. In another alternative preferred embodiment, the frame12of the racquet10can be formed without a yoke.

In a preferred embodiment, the first and second side regions26and28downwardly extend from the head portion18to form first and second throat tubes36and38of the throat portion22. The first and second throat tubes36and38converge further downwardly extend to form the handle portion20. The handle portion20includes a pallet (not shown), a grip40and a butt cap42. In alternative preferred embodiments, the handle portion20can be a tubular structure that does not include an extension of the first and second throat tubes. In this alternative preferred embodiment, the handle portion can be a tubular structure separate from either the throat portion or the head portion of the frame and attached to the throat portion through use of conventional fasteners, molding techniques, bonding techniques, adhesives or combinations thereof.

In another preferred embodiment, the head portion18is directly connected to one or both of the throat portion22and the yoke34through the use of conventional fasteners, adhesives, mechanical bonding, thermal bonding, or other combinations thereof. Alternatively, the head portion18can be separated from one or both of the throat portion and the yoke by a vibration and shock absorbing material, such as an elastomer. In yet another alternative preferred embodiment, the head portion18is integrally formed with one or both of the throat portion22and the yoke16.

The string bed14is formed by a plurality of main string segments44interwoven with a plurality of cross string segments46. The main and cross string segments44and46can be formed from one continuous piece of racquet string, or from two or more pieces of racquet string.

The head portion18of the racquet10is preferably a tubular structure shaped to define a hoop48. The hoop48can be any closed curved shape including, for example, a generally oval shape, a generally tear-drop shape, a generally pear shape, a generally circular shape and combinations thereof. The hoop48includes an outer peripheral wall50and an inner peripheral wall52. In a preferred embodiment, the hoop48includes first, second and third groups of string openings54,56and58in the outer and inner peripheral walls50and52, respectively.

Referring to FIGS.2and4-6, at least a first set of concave recesses60and a first set of channels62are formed into the outer peripheral wall50of the hoop48. The first set of concave recesses60are spaced apart and interconnected by the first set of channels62. The concave recesses60and the channels62are configured to receive and operably engage an articulating grommet assembly64. In a preferred embodiment, the concave recesses60are generally hemispherical recesses. In alternative preferred embodiments, the concave recesses can take other curved shapes such as semi-circular or semi-cylindrical. In one preferred embodiment, the concave recesses60have a depth of within the range of 2 to 8 millimeters. In a more preferred embodiment, the depth of the concave recesses is within the range of 5 to 6 millimeters. The channels62extend between the concave recesses62and preferably have a semi-cylindrical shape. Other shapes can also be used. The depth of the channels62are preferably within the range of 1 to 4 mm. In a particularly preferred embodiment, the depth of the channels62is within the range of 2 to 3 mm.

The outer surface of the outer peripheral wall50at the locations of the concave recesses60and the channels62are preferably substantially the same as the remaining outer surfaces of the outer peripheral wall50. Accordingly, the surfaces of the outer peripheral wall50at the concave recesses60and the channels62preferably receive similar surface treatments including sanding, paint layers, clear coats, etc. as the other surfaces of the outer peripheral wall. The painted and coated outer surfaces of the outer peripheral wall50are generally very smooth which significantly reduces the coefficient of friction of the surface and facilitates the articulation or relative movement of the articulating grommet assembly64with respect to the hoop48of the racquet10upon impact of a game ball (such as a tennis ball) with the string bed14.

InFIGS. 1,2,4and5, a portion of the hoop48is shown with thirteen concave recesses60connected by a set of twelve channels62. In alternative preferred embodiments, the set of concave recesses60formed into a portion or section of the hoop48can be three or more, and the set of channels62can number two or more. In one particularly preferred embodiment, the set of concave recesses60number eight and the set of channels62number seven.

The first set of string openings54are generally circular shaped openings extending through the inner and outer peripheral walls and are configured for receiving racquet string segments and/or portions of a grommet. The first set of string openings54preferably have a diameter of approximately 3 millimeters. In other embodiments, the first set of string openings can be formed of a larger diameter. The second set of string openings56extend through the outer peripheral wall50and are preferably positioned at the location of the concave recesses60. The third set of string openings58extend through the inner peripheral wall52and are generally aligned with the second set of string openings56to facilitate the passage or stringing of string segments44or46. In a preferred embodiment, the second and third set of string openings56and58are formed as through-wall slots. The length (or major dimension) of the third set of string openings58is preferably greater than the length (or major dimension) of the second set of string openings56. In a particularly preferred embodiment, the second set of string openings56have a length of 5 millimeters or greater, and the third set of string openings58have a length of 10 millimeters or greater. In alternative preferred embodiments, other lengths can be used for the second and third sets of string openings. In alternative preferred embodiments, the second and third set of string openings56and58can be formed in other shapes, such as, for example, circular, elliptical, rectangular, polygonal, irregular or combinations thereof.

Referring toFIGS. 1-6, the articulating grommet assembly64is shown. The articulating grommet assembly64is formed of at least three pivotable elements66connected by a plurality of torque transmitting arms68. Each pivotable element66includes a rounded base70and a protective barrel72extending from the base70. A string passage74is formed through each pivotable element66from the base70through the protective barrel72. A string receiving groove76is preferably formed into an outer surface of the rounded base70and the torque transmitting arms68of the grommet assembly for routing string segments from one string passage74to another.

The articulating grommet assembly64is formed of a lightweight, durable and resilient material, preferably, a thermoplastic nylon, such as nylon11. Alternatively, the articulating grommet assembly can be formed of other materials, such as, for example, a composite material, a urethane, a polyamide, a rubber, wood, aluminum, other metals, other thermoplastic materials and combinations thereof. In a preferred embodiment, the articulating grommet assembly64is formed of a generally rigid material such that rotation of one or more adjacent pivotable elements66about an axis80causes the pivotable elements66positioned on either side of the original one or more adjacent pivotable elements to receive a torque from the torque transmitting arms68.

In a preferred embodiment, the rounded base70is generally hemispherical having a radius of within the range of 2 to 4 millimeter from the pivot axis80of the pivotable element66. In a particularly preferred embodiment, the radius of the rounded base70is approximately 2.5 mm. In alternative preferred embodiments, the rounded base70can be formed in other shapes, such as for example, cylindrical, semi-cylindrical, ovoidal, other curved or bulbous shapes and combinations thereof. The protective barrel72provides a protective passageway for one of the string segments44or46through the second and third sets of openings56and58in the inner and outer peripheral walls52and50of the hoop48. The protective barrel72preferably has a length within the range of 7 to 13 mm. In a particularly preferred embodiment, the length of the barrel72can be within the range of 9 to 10 mm. The protective barrel72is preferably tubular or cylindrical having an outer diameter and an inner diameter. In one preferred embodiment, the protective barrel has an outer diameter of approximately 2.8 mm and an inside diameter of approximately 1.6 mm (the inside diameter forming part of the string passage74as it extends through the barrel72). In alternative preferred embodiments, other inner and outer diameter sizes can be used. In still other preferred embodiments, the outer shape of the barrel can take other non-cylindrical shapes. The string passage74extending through the base70and barrel72of the pivotable element66preferably has a diameter of approximately 1.6 mm. Other diameter sizes can are also contemplated. The string receiving grooves76formed into the outer surface of the rounded base70and the torque transmitting arms68of the grommet assembly64preferably have approximately 1.5 to 2.0 mm. The articulating grommet assembly64thereby preferably completely isolates the string segments44and/or46engaging the grommet assembly64from directly contacting the hoop48. As a result, the string segments44and46engaging the grommet assembly64are protected from wear and abrasion with sharp or rough surfaces of the hoop48. The string receiving grooves76and string passages74also facilitate stringing of the racquets10.

Each pivotable element66has a first cross-sectional area measured about a first plane that is orthogonal to the string bed14and parallel to the string segment extending through the pivotable element66. Each torque transmitting arm68has a second cross-sectional area measured about a second plane parallel to the first plane. The first cross-sectional area is greater than the second cross-sectional area.

The articulating grommet assemblies are preferably inserted into the corresponding locations of the hoop48(the corresponding locations of the set of concave recesses60and channels62) and further secured by the racquet string segments44and46extending through the articulating grommet assemblies64. In alternative preferred embodiments, the articulating grommet assemblies can be press-fit to the hoop48. In this configuration, at least one point on the grommet assembly remains substantially fixed in relation to the hoop48. In alternative preferred embodiments, the articulating grommet assemblies can be fixedly coupled to the hoop48through other means, such as, for example, other press-fit connections, conventional fasteners, adhesives, bonding and combinations thereof.

The articulating grommet assembly64ofFIGS. 1,2,4and5includes thirteen pivotable elements66connected by twelve torque transmitting arms68. In alternative preferred embodiments, the articulating grommet assemblies64can include three or more pivotable elements66connected by two or more torque transmitting arms68. The number of pivotable elements66can be varied to tailor the racquet design to best meet a user's needs.

Referring toFIGS. 7-9, the operation of an individual pivotable element66of the articulating grommet assembly64is shown.FIG. 7shows a transverse cross-sectional view of the hoop48of the racquet10taken about a plane that is orthogonal to the plane defined by the string bed14and that is parallel to the extension of the cross string segment48of the string bed14. When a game ball82(such as a tennis ball) impacts the string bed14(or a cross string segment48) during play, the impact causes the string to deflect in response to the impact. The deflection of the string segment48extends to the articulating grommet assembly64. The rounded base70of the pivotable element66rotates or articulates about the pivot axis80relative to the outer peripheral surface50forming the concave recess60of the hoop14. Referring toFIGS. 7-9, the second and third string openings56and58are slotted to provide space for the string segment48and the protective barrel72to rotate, pivot or articulate about the axis80and move within and relative to the hoop14without binding or being otherwise inhibited by the inner and outer peripheral walls52and50of the hoop14.

This rotation, pivoting or articulation enables to the string segment48to deflect further than it otherwise would without the rotation. This articulation or rotational movement provides an effect that is similar to that of a racquet having a longer effective string length. The rotation or articulation of the pivotable element66of the grommet assembly64relative to the hoop48enables the string bed14to deflect further upon impact with the ball and thereby provide more responsiveness and greater power transfer to the ball. Further, the increased deflection of the string bed14increases the “dwell time,” or the duration of contact between the ball and the string bed14of the racquet10upon contact, enabling the user to impart spin more easily to the ball and to achieve better overall control of the ball during play.

The unique construction of the articulating grommet assembly64with the three or more pivotable elements66connected by a plurality of torque transmitting arms68provides the additional benefit of enabling the torque or rotation of one or more pivotable elements66to be transmitted to other adjacent string segments44or46. Referring toFIGS. 5 and 7, when the ball82impacts the string bed14, the diameter of the ball causes the ball to impact two or more cross string segments46and/or two or more main string segments44(generally two to five string segments). The present invention enables the force of impact on the string bed14to allow for the affected pivotable elements66to rotate in response to the impact with the game ball82but also the pivotable elements of string segments46or44adjacent to the impact site also receive the torque or rotational moments due to the torque transmitting arms68connecting the pivotable66. Rotation of two or more pivotable elements66due to an impact with the game ball creates a torque on the adjacent pivotable elements due to the torque transmitting arms68direct connection to the adjacent pivotable elements. This transmission of torque can allow for the adjacent pivotable elements66to also move, rotate, articulate or pivot with respect to the hoop48in response to the impact. In other words, the pivotable elements66are pivotable about the pivot axis80, which is parallel to the string bed plane. Deflection of one of the cross or main string segments46or44extending through one of the pivotable elements due to impact with the game ball causes the one pivotable element66to rotate about the axis80and to produce a torque on the pivotable elements66positioned on opposite sides of (or directly adjacent to) the one pivotable element66through the torque transmitting arms68. The torque being the moment of a force or a system of forces urging, or causing, rotation of such adjacent pivotable elements.

The result of such movement can allow for further deflection of the string bed14at and around the impact site, increased dwell time between the ball82and the string bed14, and an enlarged sweet spot. The torque transmitting arms68enable the string bed14and the racquet as a whole to be more responsive, perform better and possess an enlarged sweet spot.

Referring toFIG. 7, each pivotable element66has a first cross-sectional area when taken about a first plane orthogonal to the string bed and parallel to the string segment46extending therethrough. Referring toFIG. 3, each torque transmitting arm68has a second cross-sectional area when taken about a second plane that is parallel to the first plane. The first cross-sectional area is greater than the second cross-sectional area.

Referring toFIGS. 13-15, the enlarged sweet spot obtained through incorporation of the present invention into a racquet is demonstrated.FIGS. 13-15show the results of coefficient of restitution (“COR”) tests performed on three separate racquets. Each of the three racquets have similar head and hoops shapes and sizes. All three racquets have a hoop or head size of approximately 110 square inches. The head or hoop shapes of the three racquets are conventional, traditional generally ovoidal head shapes.

FIGS. 13-15illustrate mappings of the areas of various COR values for a racquet of the present invention and for two representative prior art racquets. The COR is the ratio of the rebound velocity of a ball, such as, for example, a tennis ball, to the incoming velocity of the ball. The COR values ofFIGS. 13-15were measured by using an incoming velocity of 90 feet per second, +/−5 feet per second. Each mapping reflects the COR values resulting from the impacts of the ball with the string bed at numerous, distributed locations about the string bed. The racquet is supported in the test apparatus only at the handle. In particular, the test apparatus secures the proximal end of the handle (approximately the proximal 6 inches of the handle). The attachment of the test apparatus to the racquet restricts the proximal end of the handle from moving or twisting along the x, y or z axes. Each racquet ofFIGS. 13-15possessed a string tension of 55 lbs tension, measured in a strung condition generally at the center of the string bed.

FIG. 13illustrates the areas of COR for a racquet having substantially the same frame as the racquet ofFIG. 15, but without the articulating grommet assemblies64of the present invention. The racquet ofFIG. 13is a racquet model produced by Wilson Sporting Goods Co. of Chicago, Ill., and serves as a control racquet. The numerical values of the COR areas for the racquet mapped inFIG. 13are provided in Table 1. The maximum COR reading for the racquet ofFIG. 13was 0.35 with an area of 0.35 COR of 3.14 square inches.

FIG. 14illustrates the areas of COR for a representative prior art racquet. The racquet is a Prince® racquet, Model Blue EX03′ produced by Prince Tennis of Bordentown, N.J. The racquet has generally the same shape, approximately the same head size, and a similar swing weight as the racquets of FIGS.13and15, and was selected as a representative prior art racquet. The numerical values of the COR areas for the racquet mapped inFIG. 14are provided in Table 1. The maximum COR reading for the racquet ofFIG. 14was 0.35 with an area of 0.35 COR of 3.02 square inches.

FIG. 15illustrates the enlarged areas of COR for a racquet built in accordance with a preferred embodiment of the present invention. The racquet ofFIG. 15includes two articulating grommet assemblies64and corresponding sets of concave recesses60and channels62generally positioned at the 3 and 9 o'clock locations about the hoop48. Each articulating grommet assembly of the racquet ofFIG. 15includes eight pivotable elements66(and eight corresponding concave recesses60) and seven torque transmitting arms68connecting the eight pivotable elements66. Accordingly, the articulating grommet assemblies of the racquet ofFIG. 15actively engage and effect eight separate cross string segments48of the racquet. The numerical values of the COR areas for the racquet mapped inFIG. 15are also provided in Table 1. The maximum COR reading for the racquet ofFIG. 15was 0.40 with an area of 0.40 COR of 1.27 square inches, and an area of 0.35 COR or greater of 7.78 square inches.

InFIGS. 13-15, the line labeled 0.45 represents the border of the area on the strings where the COR was 0.45 or greater. The line indicated as 0.40 represents the border of the area on the strings where the COR was 0.40 or greater. Similarly, the other lines inFIGS. 13-15represent borders for the areas on the strings for various values of COR. The “sweet spot” of the racquet is generally defined as the area of the string bed having one of the three following COR values: 2.5 or greater, 3.0 or greater, or 3.5 or greater. The numbers on the horizontal and vertical axes ofFIGS. 13-15represent the distance from the center of the strung surface. For example, the center of the strung surface is indicated as 0.00. Two inches to the right of center of the strung surface is indicated as 2.00, 2 inches to the left of the center is indicated as −2.00, etc.

Table 1 below summarizes the COR data provided onFIGS. 13-15.

A comparison ofFIGS. 13-15and the data of Table 1 indicates that the racquet made in accordance with the invention has a significantly greater “sweet spot” than either of the prior art racquets ofFIGS. 13 and 14. The racquet ofFIG. 15of the present invention has greater area within most of the border lines for various CORs, and achieves a higher level of COR (0.40). In the 0.35 COR area, the improvement in the sweet spot area is dramatic with increases over 140%

The incorporation of the present invention significantly improves the racquet's performance by increasing the effective length of the applicable string segments. The articulating grommet assemblies provide an effect that is similar to the effect achieved with longer racquet string segments or a larger hoop or string bed. The present invention provides this significant advantage without requiring an increase in the size of the head portion and the corresponding undesirable increase in the polar moment of inertia of the racquet.

Referring toFIGS. 10-12, in preferred embodiments of the present invention, the articulating racquet assemblies64can be positioned in one or more various positions about the hoop48thereby improving the performance of various regions of the string bed of the racquet10. InFIG. 10, two articulating grommet assemblies are shown positioned at the 3 and 9 o'clock positions. InFIG. 11, the articulating grommet assemblies64are positioned at the 12 and 6 o'clock positions about the hoop48of the racquet thereby primarily effecting the main string segments44of the string bed14. InFIG. 12, the articulating grommet assemblies are shown positioned at the 2, 4, 8 and 10 o'clock positions about the hoop48of the racquet10. This configuration serves to improve the performance of the string bed that generally provides the lowest level of performance. In other preferred embodiments, one or more articulating grommet assemblies can be positioned in other locations and other numbers about the hoop. The present invention allows for a wide range of potential arrangements and configurations of the articulating grommet assemblies on or about the hoop of a racquet, thereby maximizing the flexibility of the racquet design and allowing the racquet to be customized or tailored to meet the needs of a particular player or type of player.

While the preferred embodiments of the present invention have been described and illustrated, numerous departures therefrom can be contemplated by persons skilled in the art. Therefore, the present invention is not limited to the foregoing description but only by the scope and spirit of the appended claims.