Racquet strung with bypass string pattern

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to sports racquets, such as tennis rackets, badminton racquets, squash racquets and racquetball racquets used for hitting a projectile such as a ball, and more particularly to a method of stringing a sports racquet used for hitting a projectile.

BACKGROUND OF THE INVENTION

In the most conventional sort of strung sports racquets, the striking area is defined by a head frame that is roughly oval in shape. “Racquet,” as used herein, encompasses racquetball racquets, tennis rackets, badminton racquets, squash racquets and any other sports implement that has a head which is strung with string or netting and which is designed to intercept and return a projectile. Holes are made through the frame, typically in the plane of the strung area, for the passage of string therethrough. Racquets are generally strung such that one string weaves through the holes that are positioned on opposite sides of the frame in a consecutive fashion, forming multiple string segments. As a result, two directly connected segments of the string are situated adjacent each other in the strung racquet.

As the ball impacts a string, a tensile force is placed on the string which will have a tendency to pull the string through the string hole, and this tensile force is communicated to the adjacent string segment of the string. If the adjacent string segment is not also impacted, there would be a tendency of the adjacent strung segment to relieve some of the tensile force by lengthening. However, when two adjacent string segments are impacted at the same time, there is no opportunity for one string segment to relieve the stress placed on the other. Instead, tensile force is exerted on both string segments toward the projectile but in opposite directions on the string of which the string segments are a part, tending to pull the string apart. This acute stress shortens the life of the string and causes string failure. Further, where a large component of a ball's momentum is absorbed by a single string segment, other segments adjacent on the continuous string to the impacted segment can contribute to the impacted strings elongation and resiliency, thereby contributing a more lively feeling to play. But where two or more segments that are adjacent each other on the continuous string absorb substantial portions of a ball's impact, they are less available in permitting each other to yield or deflect. This results in a more wooden or board-like feel to play.

Thus, it is desirable to improve the life of strings of a sports racquet and to reduce the amount of stress the ball exerts at impact on each of the connected string segments, and it is desirable to enhance liveliness and resiliency in the behavior of impacted string segments.

SUMMARY OF THE INVENTION

One aspect of the invention is a method used to string a sports racquet for hitting a projectile and the string racquet produced thereby. The method includes the step of drawing a string from a first side of a racquet frame toward a second side opposite the first side to form a first string segment. The string is strung through a string anchoring point at a first location on the second side and drawn from the first location on the second side to a second location on the second side. The string is then strung through a string anchoring point at the second location and passed back to the first side of the frame. The second side is spaced from the first side a predetermined distance that is preselected such that the projectile cannot substantially impact both the first and second string segments when the racquet hits the projectile.

Another method for stringing a sports racquet includes the step of drawing a string from a first side of the racquet frame toward a second side opposite the first side to form a first string segment. The string is strung through a first string hole at a first location on the second side. The string is drawn from the first location on the second side to a second location on the second side spaced from the first location. The string is then strung through a second string hole at the second location. The string is then passed back to the first side of the frame with at least two other string holes on the frame interposed between the first and second string holes. The result is a string racquet in which string segments that are adjacent each other on the string occupy positions in the string that are substantially parallel to each other but which are spaced apart by at least two other, and in some embodiments three or more, string segments.

Another aspect of the invention is directed to a string anchoring system for a sports racquet. The string anchoring system preferably includes a bumper having an outer surface, an inner surface and a plurality of anchoring points formed therethrough. The bumper surrounds an outer edge of a frame of the sports racquet and the anchoring points are adapted to guide a string through the frame of the sports racquet. A first string path is formed in the outer surface of the bumper between a first and second location and a second string path is formed in the outer surface of the bumper between a third and fourth location. The third, first, fourth and second locations are linearly arranged along the outer surface such that the fourth location is between the first and second locations. The second string path is displaced from the first string path such that the first and second string paths are adapted to receive string portions wherein the string portions disposed in the string paths do not saw at each other. In a preferred embodiment, the string anchoring system defines three such overlapping string paths, which however are routed so as to substantially avoid each other. Alternatively, the string paths may be formed by an external top surface of the racquet frame itself rather than in a bumper.

The present invention is applicable to shafted as well as nonshafted racquets and to racquets of conventional string designs as well as “longstring” designs (see, e.g., U.S. Pat. No. 5,919,104 assigned to the assignee hereof). The present invention enhances string life as well as resiliency in play in that a ball cannot impart as much energy into two string-adjacent string segments at the same time. Therefore, these string-adjacent string segments (i.e., having the relation to each other shown in

FIG. 2

) are more able to contribute to the resiliency and deflection of those string segments taking most of the force.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the invention and their advantages may be discerned from the following description when taken in conjunction with the drawings, in which like characters number like parts and in which:

FIG. 1

is a front view of the sports racquet of the present invention, a portion of a handle being cut away to show internal detail;

FIG. 2

is a side elevation view of a string used to string the sports racquet;

FIG. 3

is a perspective view of a conventional bumper molding according to the prior art;

FIG. 4

is a top view of the bumper that is disposed on a racquet as illustrated in

FIG. 1

;

FIG. 5

is a cross sectional view taken substantially along line

5

—

5

of

FIG. 4

, and illustrating a bypass string pattern according to the present invention;

FIG. 6

is a side view of a racquetball before and during an impact on a racquetball racquet string bed;

FIG. 7

is a top view of the bumper illustrated in

FIG. 4

with a string drawn through the bumper;

FIG. 8

is a top view of the bumper strung with an alternative string pattern;

FIG. 9

is a top view of the bumper strung with an alternative string pattern;

FIG. 10

is a top view of the bumper with an alternative bypass string pattern in which only one hole is bypassed;

FIG. 11

is a schematic front view of a racquet strung by the bypass string pattern of the present invention; and

FIG. 12

is a schematic front view of a racquet strung using another form of the bypass string pattern.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT

FIG. 1

illustrates a sports racquet

10

strung by the bypass string pattern of the present invention. The sports racquet

12

includes a handle

14

and a frame

16

extending from the handle

14

. While a nonshafted racquetball racquet

12

is illustrated, the present invention has equal application to shafted racquets such as those used for tennis, squash and badminton. The handle or stem

14

preferably is formed as a hollow chamber with a transverse anchoring pin

13

positioned therein (see also

FIG. 12

) for supporting the main string or “longstring” segments of the strung racquet. While the present invention has been illustrated using a “longstring” racquet, it has equal application to other racquets which do not extend the longitudinal string segments into a handle or stem. The frame

16

defines a head

22

and a narrow throat

24

that leads to the handle

14

. The frame

16

includes opposed sides between which is strung a string bed

30

. The string bed

30

is the portion of the racquet that is meant to contact a projectile, such as a ball or shuttlecock. The opposed sides of the frame include a first side

18

located at the throat

24

and a second side

20

opposite the first side

18

located at the top of the frame

16

. The frame also includes lateral side portions

19

and

21

.

The handle

14

and the frame

16

may be formed of any of several strong materials. Preferably, the handle and frame are formed from a laminated composite of resin-impregnated carbon fiber sheets.

The racquet

10

includes a plurality of string segments. A string

31

of the sort used to string the sports racquet is illustrated in FIG.

2

. The string

31

includes a plurality of segments

32

that are adjacent to each other on the string. In use, the string segments are positioned within the string bed

30

of the racquet

12

. The string

31

forms horizontal segments

32

and vertical segments

34

. The horizontal segments

32

are cross strings that extend between lateral sides

19

and

21

. The vertical segments

34

include a plurality of main strings that are disposed at the center of the racquet

12

. The main string vertical segments extend from the second side

20

of the frame

16

through the throat

24

of the frame

16

, and around an anchoring pin

13

positioned in the handle as illustrated by commonly owned U.S. Pat. No. 5,919,104 to Mortvedt et al. The remainder of the vertical string segments extend from the first side

18

to the second side

20

of the frame

16

(see FIG.

12

).

The frame

16

is comprised of a tubular support member

40

whose cross section is roughly oval in shape. The tubular support member

40

of the frame

16

includes a plurality of anchoring points or holes

42

(see

FIG. 5

) positioned around the head

22

of the frame

16

for receiving the racquet string.

Bumpers are generally positioned around the top outer edge of the racquet.

FIG. 3

illustrates a conventional prior art bumper which is normally laced to the bow or the top end of the racquetball racquets. The bumper is intended to protect the frame and the string segments of the racquet from court abrasions. In conventional designs using frames with string holes, the bumper provides grommets

100

that direct and protect strings as they penetrate through string holes in the frame.

General Electric developed a plastic, during the early 1970's, for better impact and abrasion resistance. The generic “polycarbonate” was given the trademark LEXAN®. Current variations on this resin are manufactured by GE, Dow, Mobay, Polymer Resources, and Shuman.

This material was tested as a bumper in the present invention and appears to provide superior impact and abrasion resistance performance. Other materials may also be effective, such as other amorphous polyesters, or polyamides. Generally, any polymer which meets a criterion of greater than 10 ft-lbs./inch of notch according to the ASTM D256A testing standard (Izod impact, ⅛″ specimen) can be substituted. The benefits of using polycarbonate include better abrasion resistance, thus longer lasting string protection; better impact resistance, thus longer racquet service life; behavior as a structural adjunct for impact protection, therefore materials in the racquet structure dedicated to this purpose may be removed, or rededicated to stiffening the bow region; and easier racquet installation than is the case with conventional bumpers.

In the illustrated embodiment of

FIG. 1

, a bumper

50

surrounds the outer edge

26

of the top of frame

16

. The bumper

50

provides a string anchoring system that guides the string while stringing the racquet. The bumper

50

is fit onto the outer surface of the tubular support member

40

of the frame

16

and centered at the top of the racquet. The bumper

50

may be bent around the periphery of the frame

16

from a piece of straight stock or may be custom molded. Preferably, the bumper

50

is stretched onto the tubular support member

40

of the frame

16

so that the bumper

50

is under tension.

A bumper

50

according to the invention includes an outer surface

62

(

FIG. 4

) and an inner surface

64

(

FIG. 5

) with a plurality of anchoring points or holes

52

therethrough. The bumper

50

also includes an outer edge

68

along each side of the outer surface

62

. The plurality of anchoring points or holes

52

are spaced apart such that the bumper holes

52

align with the holes

42

in the tubular support member

40

of the frame

16

.

The bumper

50

includes a plurality of spaced apart projections

72

that are aligned in a row along the edges

68

of the bumper

50

. The projections

72

provide additional protection for the frame

16

from court abrasions.

FIG. 5

illustrates a cross-section of the bumper

50

installed on the tubular support member

40

of the racquet frame

16

. The inner surface

64

of the bumper includes a plurality of downwardly extending grommets

70

wherein one grommet

70

extends from each of the holes

52

disposed in the bumper

50

. The bumper

50

is positioned around the outer edge

26

of the frame

16

such that the downwardly extending grommets

70

of the inner surface

64

are inserted through the holes

42

in the frame

16

. As a result, the inner surface

64

of the bumper

50

is positioned adjacent to the outer edge

26

of the frame

16

.

The downwardly extending grommets

70

of the bumper

50

guide the racquet strings through the holes

42

in the tubular support member

40

of the frame

16

. The downwardly extending grommets

70

facilitate the process of stringing the racquet. Once the racquet is strung, the downwardly extending grommets

70

provide support for the newly formed string segments of the racquet. Preferably, the grommets

70

are flexible so as not to inhibit string deflection to any substantial degree.

As shown in

FIGS. 4 and 5

, the bumper

50

directs the string to bypass at least two holes

42

in the frame

16

. The bypass pattern enables string segments that are adjacent each other on the string to be displaced from each other by relatively large distances in the strung racquet. In the illustrated embodiment, the bumper

50

includes a first string path

82

, that guides the string from a string anchoring point at a first location

1

HL to a string anchoring point at a second location

3

HR. A second string path

83

guides the string from an anchoring point at a third location

2

HL to an anchoring point at a fourth location

2

HR. A third string path

84

guides the string from an anchoring point at a fifth location

3

HL to an anchoring point at a sixth location

1

HR.

The first, second, third, fourth, fifth and sixth locations are linearly arranged along the outer surface of the bumper in an order denoted by there identifying characters—the character number indicating relative proximity to the centerline C, with “L” and “R” denoting “left” and “right”. Thus, location

2

HL is the second location or hole to the left of the center line C.

The third location

2

HL is located to one side of the first location

1

HL remote from the second location

3

HR and the fourth location

2

HR is located between the first location

1

HL and the second location

3

HR. The fifth location

3

HL is located to one side of the third location

2

HL remote from the first location

1

HL and the sixth location

1

HR is located between the first location

1

HL and the second location

3

HR.

The second location

3

HR is positioned a predetermined distance from the first location

1

HL, the fourth location

2

HR is positioned a predetermined distance from the third location

2

HL and the sixth location

1

HR is positioned a predetermined distance from the fifth location

3

HL. The distance between locations is predetermined according to a formula discussed below. A raised rim

80

forms the outer edge of the first and third string paths

82

and

84

, respectively, thereby confining the strings in the string paths of the bumper

50

and providing the strings some protection from impact.

As shown in

FIG. 4

, the first string path

82

starts left of the center C of the bumper

50

at an anchoring point or hole at a first location

1

HL. The first string path

82

takes the form of a channel extends along the raised rim

80

of the bumper to an anchoring point or hole at a second location

3

HR. The first string path

82

guides a portion of the string between the spaced apart anchoring points at locations

1

HL and

3

HR. The string path positions the string segments such that adjacent string segments on the string are parallel but spaced apart from each other in the string bed of the racquet.

The second string path

83

, illustrated in

FIG. 4

, starts at an anchoring point or hole at a third location

2

HL. A center section of the second string path

83

is positioned outward or topographically above that of the first string path

82

. The second string path

83

consists of a beginning channel or trench

83

a

which extends rightward from string hole

2

HL, and terminates in an ending channel or trench

83

c

which extends leftward from string hole

2

HR. A center section

83

b

of the second string path

83

is shown in dotted line, and bridges and connects portions

83

a

and

83

c

. The center portion

83

b

is topographically above, or elevated with respect to, the channels making up string paths

82

and

84

. When a string is disposed in the string paths, the string portions within the first and second string paths do not saw each other.

The second string path

83

extends from anchoring point or hole at the third location

2

HL to an anchoring point or hole at the fourth location

2

HR that is positioned to the right of the center C of the bumper

50

. The second string path

83

also displaces the string such that adjacent string segments on the string are parallel and spaced apart from each other in the string bed of the racquet. The anchoring points or holes at the third and fourth locations

2

HL and

2

HR are positioned the same distance from each other as the anchoring points or holes at the first and second locations

1

HL and

3

HR.

The bumper

50

also includes a third string path

84

, that also takes the form of a channel and is substantially parallel to the first and second string paths

82

and

83

, respectively. The third string path

84

is positioned such that when the string is disposed in the first, second and third string paths the string portions within the string paths do not saw at each other. As shown in

FIG. 4

, the third string path

84

guides the string from the anchoring point or hole at a fifth location

3

HL along the raised rim

80

of the bumper to the anchoring point or hole at a sixth location

1

HR. The holes at the fifth and sixth locations

3

HL and

1

HR, respectively, are also positioned the same distance from each other as first and second locations

1

HL and

3

HR and the third and fourth locations

2

HL and

2

HR. As a result, the third string path also displaces the string such that adjacent string segments on the string are parallel and spaced apart from each other in the string bed of the racquet.

Alternatively, the string may be guided by first, second and third string paths that are formed within the outer face of the outer edge of the racquet itself rather than the outer surface of a bumper.

As illustrated in

FIGS. 4 and 5

, the string paths guide the string a predetermined distance which causes the string to bypass intermediate anchoring points in the frame of the racquet. The predetermined distance is preselected such that when the racquet hits a projectile, such as a racquet ball, the racquet ball cannot substantially impact adjacent string segments.

The predetermined distance, x, is based on the formula

x=f

(π

r

)

where r is the radius of the racquet ball. As shown in

FIG. 6

, the racquetball

90

substantially flattens as it impacts a racquet. As a result, the width of the surface that the racquetball contacts in the string bed approaches one-half of the circumference of the racquetball. This circumferential distance is πr, where r is the radius of the projectile. It is desirable that the spacing between connected string segments be at least

(\frac{π r}{2}),

where r is equal to the radius of the racquetball, so that the ball does not substantially impact two string segments, adjacent each other on the string, at the same time. As a result, the string paths extend about 1.8 inches, and preferably the string paths extend approximately 2 inches between connected anchoring points.

FIG. 7

is a top view of the bumper

50

with the racquet string installed therein. As described above, the first string path

82

, the second string path

83

and the third string path

84

guide the string to spaced apart anchoring points thereby bypassing adjacent anchoring points. FIG.

8

and

FIG. 9

illustrate alternative string patterns where only two overlapping string paths are occupied by a string.

FIG. 8

illustrates a string strung through the second string path

83

and the third string path

84

.

FIG. 9

illustrates a string strung through the first string path

82

and the second string path

83

.

FIG. 10

illustrates an alternative bypass pattern that includes two string paths. The string paths in the alternative bypass pattern guide the string to bypass only one string hole. In the illustrated alternative embodiment, the bumper

150

includes a first string path

182

defined between hole

1

HL and hole

2

HR, with hole

1

HR therebetween. The bumper also includes a second string path

183

defined between hole

2

HL and hole

1

HR, with hole

1

HL therebetween. The centerline C is between holes

1

HL and

1

HR.

FIG. 11

illustrates a racquet strung with a bypass pattern according to a preferred embodiment of the present invention. In the illustrated embodiment, the main strings of the racquet are strung by starting at the head of the racquet on the left side at hole

1

HL. The short side of the racquet is strung first by feeding a string through the hole

1

HL down to the first side of the racquet thereby forming a string segment. The string is wrapped around groove G

4

that is disposed in the anchoring pin

13

. The string is fed up through the right side of the racquet to hole

4

HR thereby forming another string segment. The string is clamped at hole

1

HL near the head of the racquet. The string is also tensioned at hole

4

HR and then it is clamped near the head of the racquet. The remainder of the short side of the racquet is strung by feeding the string through adjacent hole

5

HR and bringing the string down to hole

1

TR in the throat of the frame forming a string segment. The string is then drawn over to hole

2

TR and back up to hole

6

HR at the head of the frame forming a string segment. At each hole, the string is tensioned and clamped before it is drawn to the next hole. From hole

6

HR, the string skips hole

7

HR and is drawn through hole

8

HR. The string is brought down from hole

8

HR at the head to hole

3

TR located in the throat forming a string segment. The string is tensioned and clamped and brought to adjacent hole

2

TR. The string is tied off at hole

2

TR.

The long side of the racquet is strung by placing the string from hole

1

HL in the first string path

82

which guides the string to hole

3

HR. The string is drawn through hole

3

HR down to the first side of the racquet thereby forming a string segment. The string is wrapped around groove G

3

that is disposed in the anchoring pin

13

. The string is fed up the left side of the handle towards the head and hole

2

HL forming a string segment. Next, the string is fed through hole

2

HL and then positioned in the second string path

83

. The second string path

83

guides the string to hole

2

HR. The string is fed through hole

2

HR and drawn to the first side of the racquet forming a string segment. The string is wrapped around groove G

2

that is disposed in the anchoring pin and brought up the left side of the handle to the head of the racquet forming a string segment. The string is brought through hole

3

HL, tensioned and clamped near the head of the racquet. The string is positioned in the third string path

84

and guided to hole

1

HR. The string is fed down through hole

1

HR towards the first side of the racquet forming a string segment. The string is wrapped around groove G

1

that is disposed in the anchoring pin. The string is brought back to the second side or head of the racquet to form a string segment. The string is then drawn through hole

4

HL, tensioned and clamped.

The remaining main strings on the long side of the racquet are strung by guiding the string from hole

4

HL to adjacent hole

5

HL. The string is brought down through hole

5

HL to hole

1

TL in the throat of the left side of the racquet thereby forming a string segment. The string is tensioned and clamped. The string is drawn through adjacent hole

2

TL and up through hole

6

HL forming a string segment. The string is again tensioned and clamped. The string is guided past hole

7

HL and drawn through hole

8

HL. The string is fed down to hole

3

TL to form the last vertical string segment, tensioned and clamped.

The cross strings of the racquet are formed by feeding the string up to hole

4

TL and under the first main string segment. The string is then weaved through the vertical string segments across the racquet to hole

4

TR. The string is tensioned and clamped near hole

4

TR. The string is fed down and through hole

3

TR. The string is then weaved across the vertical string segments of the racquet to hole

3

TL on the left side of the racquet. The string is brought up the frame of the racquet and drawn through hole

5

TL. The string is weaved across the vertical string segments back to the right side of the racquet and through hole

5

TR. The string is tensioned and clamped near hole

5

TR. The remaining cross strings are formed in an identical fashion by bringing the string through a hole on the right side of the racquet, weaving the string across the racquet and drawing the string through a hole on the left side of the racquet.

FIG. 12

schematically illustrates a bypass string pattern used on the cross strings. As starting at location

301

on the left side of racquet

350

, string is passed to right side location

302

. Right side locations

304

,

306

and

308

are skipped and location

310

is used to pass this string back through the bed to left location

309

. The string is then routed downward past consecutive left locations

307

and

305

to location

303

, to begin another stringing cycle. The stringing pattern results in string-adjacent cross string segments which are three segments apart from each in the string bed.

While a bypass string pattern skipping two holes is illustrated and described, the bypass string pattern could include skipping any larger desired number of holes, such as three or a mixture thereof to string the racquet. The bypass string pattern may also be implemented on racquets that are strung in a different order than the illustrated embodiment.

The string paths disposed in the bumper simplify the process of stringing the racquet and provide a guide for the bypass string pattern. The bypass pattern enables the user to position adjacent string segments a distance apart from each other in the string bed. As a result, in use, a ball will not substantially impact both of two directly connected main string segments at the same time. Adjacent string segments are able to relieve some of the stress placed in the string segments that are impacted by the ball. The main string segments are able to move independent of each other resulting in a livelier ball response and a longer string life.

Therefore, while the invention has been described with respect to the illustrated embodiment, it is not limited thereto, but only by the scope and spirit of the appended claims.

Number	Name	Date	Kind
4118029	Septier	Oct 1978	A
4162791	Seehase	Jul 1979	A
4765621	Game	Aug 1988	A
5054779	Marrello	Oct 1991	A
5232219	Tseng	Aug 1993	A
5255912	Tseng	Oct 1993	A
5263709	Tseng	Nov 1993	A
5342044	You	Aug 1994	A
5383662	Gabrielidis	Jan 1995	A
5435550	You	Jul 1995	A
H1710	Davis	Feb 1998	H
5919104	Mortvedt et al.	Jul 1999	A
5993337	Janes et al.	Nov 1999	A
6050909	Severa et al.	Apr 2000	A
6062994	Grimes et al.	May 2000	A
6432005	Lin	Aug 2002	B1

Racquet strung with bypass string pattern

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

US Referenced Citations (16)