RACKET
20210268340 · 2021-09-02
Assignee
Inventors
Cpc classification
A63B51/001
HUMAN NECESSITIES
International classification
Abstract
A face of a racket includes a plurality of first longitudinal threads, a plurality of second longitudinal threads, and a plurality of transverse threads. The first longitudinal threads and the second longitudinal threads are arranged alternately from a center of the face toward outside in a width direction of the racket. A material of each first longitudinal thread is different from a material of each second longitudinal thread. A tension of the first longitudinal thread may be different from a tension of the second longitudinal thread. Preferably, a ratio (N1/N2) of a number N1 of the first longitudinal threads to a number N2 of the second longitudinal threads is greater than or equal to 2/8, but less than or equal to 8/2.
Claims
1. A racket comprising: a head; and a face whose contour is formed by the head, wherein the face includes a plurality of first longitudinal threads, a plurality of second longitudinal threads, and a plurality of transverse threads, and specifications of each first longitudinal thread are different from specifications of each second longitudinal thread.
2. The racket according to claim 1, wherein a material of the first longitudinal thread is different from a material of the second longitudinal thread.
3. The racket according to claim 2, wherein the material of the first longitudinal thread is a resin composition whose base material is a polyester, and the material of the second longitudinal thread is a resin composition whose base material is a nylon.
4. The racket according to claim 2, wherein the material of the first longitudinal thread is a resin composition whose base material is a polyester, and the material of the second longitudinal thread is natural gut.
5. The racket according to claim 2, wherein the material of the first longitudinal thread is a resin composition whose base material is a nylon, and the material of the second longitudinal thread is natural gut.
6. The racket according to claim 1, wherein an elongation rate E1 of the first longitudinal thread is different from an elongation rate E2 of the second longitudinal thread.
7. The racket according to claim 6, wherein a ratio (E1/E2) of the elongation rate E1 of the first longitudinal thread to the elongation rate E2 of the second longitudinal thread is less than or equal to 48/52, or is greater than or equal to 52/48.
8. The racket according to claim 1, wherein a tension T1 of the first longitudinal thread is different from a tension T2 of the second longitudinal thread.
9. The racket according to claim 8, wherein a ratio (T1/T2) of the tension T1 of the first longitudinal thread to the tension T2 of the second longitudinal thread is less than or equal to 48/52, or is greater than or equal to 52/48.
10. The racket according to claim 1, wherein a ratio (N1/N2) of a number N1 of the first longitudinal threads to a number N2 of the second longitudinal threads is greater than or equal to 2/8, but less than or equal to 8/2.
11. The racket according to claim 1, wherein each of the first longitudinal threads is adjacent to one or two of the second longitudinal threads, and each of the second longitudinal threads is adjacent to one or two of the first longitudinal threads.
12. The racket according to claim 11, wherein the first longitudinal threads and the second longitudinal threads are arranged alternately from a center of the face toward outside in a width direction of the racket.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
[0027]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Hereinafter, the present invention is described in detail based on preferred embodiments with appropriate reference to the accompanying drawings.
[0029]
[0030] The frame 4 includes a head 14, two throats 16, and a shaft 18. The head 14 forms the contour of the face 12. The front shape of the head 14 is substantially an ellipse. The major axis direction of the ellipse coincides with the axial direction Y of the tennis racket 2. The minor axis direction of the ellipse coincides with the width direction X of the tennis racket 2. One end of each throat 16 is continuous with the head 14. At the vicinity of the other end thereof, the throat 16 merges with the other throat 16. The throats 16 extend from the head 14 to the shaft 18. The shaft 18 extends from the location where the two throats 16 merge together. The shaft 18 is formed so as to be continuous with, and integrated with, the throats 16. A portion of the head 14, the portion being positioned between the two throats 16, is a yoke 20.
[0031] The frame 4 is hollow. The material of the frame 4 is a fiber reinforced resin. In the present embodiment, the matrix resin of the fiber reinforced resin is a thermosetting resin. The thermosetting resin is typically an epoxy resin. The fibers of the fiber reinforced resin are typically carbon fibers. The fibers are filament fibers.
[0032] As shown in
[0033] The head 14 further includes a plurality of holes 24. Each hole 24 extends through the head 14. The plurality of holes 24 are arranged over substantially the entire periphery of the head 14.
[0034] The grip 6 is formed by a tape wound around the shaft 18. The grip 6 suppresses a slip between a hand of a player and the tennis racket 2 when the tennis racket 2 is swung. The end cap 8 is attached to the end of the grip 6.
[0035] As shown in
[0036] The material of the grommet 10 is typically a synthetic resin that is softer than the frame 4. The racket 2 may include a plurality of grommets 10. Each grommet 10 may be spaced apart from its adjacent grommet(s) 10. The number of pipes 28 of each grommet 10 may be one.
[0037] The grommet 10 is attached to the head 14. In a state where the grommet 10 is attached to the head 14, the base 26 is accommodated in the grommet groove 22. The base 26 may partly protrude from the grommet groove 22. In the state where the grommet 10 is attached to the head 14, the pipes 28 extend through the respective holes 24. Each pipe 28 is passed through a corresponding one of the holes 24.
[0038]
String
[0039] The tennis racket 2 includes a first main string.
[0040] The tennis racket 2 includes a second main string.
[0041] The tennis racket 2 includes a cross string.
[0042]
[Specifications of Longitudinal Threads]
[0043] The specifications of each first longitudinal thread 30a are different from the specifications of each second longitudinal thread 30b. Therefore, the tennis racket 2 can have both the advantages of the first longitudinal thread 30a and the advantages of the second longitudinal thread 30b.
[1. Difference in Material]
[0044] A typical difference in specifications between the first longitudinal thread 30a and the second longitudinal thread 30b is a difference in material. One example difference in material is that the first longitudinal thread 30a is formed by using a resin composition and the second longitudinal thread 30b is formed by using a different resin composition. Examples of such a difference in resin composition include a difference in base material polymer, a difference in additive agent, and a difference in additive agent amount. Another example difference in material is that one longitudinal thread is formed by using a resin composition and the other longitudinal thread is made of natural gut.
[1.1 Polyester and Nylon]
[0045] The material of the first longitudinal thread 30a may be a resin composition whose base material is a polyester, and the material of the second longitudinal thread 30b may be a resin composition whose base material is a nylon. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is small. The first longitudinal thread 30a can contribute to spin performance and control performance On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is great. The second longitudinal thread 30b can contribute to rebound performance and hitting feeling. The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. Alternatively, the material of the second longitudinal thread 30b may be a resin composition whose base material is a polyester, and the material of the first longitudinal thread 30a may be a resin composition whose base material is a nylon.
[1.2 Polyester and Natural Gut]
[0046] The material of the first longitudinal thread 30a may be a resin composition whose base material is a polyester, and the material of the second longitudinal thread 30b may be natural gut. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is small. The first longitudinal thread 30a can contribute to spin performance and control performance On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is great. The second longitudinal thread 30b can contribute to rebound performance and hitting feeling. The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. Alternatively, the material of the second longitudinal thread 30b may be a resin composition whose base material is a polyester, and the material of the first longitudinal thread 30a may be natural gut.
[1.3 Nylon and Natural Gut]
[0047] The material of the first longitudinal thread 30a may be a resin composition whose base material is a nylon, and the material of the second longitudinal thread 30b may be natural gut. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is relatively small. The first longitudinal thread 30a can contribute to spin performance and control performance On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is relatively great. The second longitudinal thread 30b can contribute to rebound performance and hitting feeling. The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. Alternatively, the material of the second longitudinal thread 30b may be a resin composition whose base material is a nylon, and the material of the first longitudinal thread 30a may be natural gut.
[1.4 Grade]
[0048] The grade of the base material of the first longitudinal thread 30a may be different from the grade of the base material of the second longitudinal thread 30b. For example, the material of the first longitudinal thread 30a may be a resin composition whose base material is a polyester, and the material of the second longitudinal thread 30b may be a resin composition whose base material is a different polyester. The polyester of the first longitudinal thread 30a and the polyester of the second longitudinal thread 30b may be different from each other in terms of, for example, the raw material, components, molecular weight, crystallization degree, thermal history, and/or machining history. The material of the first longitudinal thread 30a may be a resin composition whose base material is a nylon, and the material of the second longitudinal thread 30b may be a resin composition whose base material is a different nylon. The nylon of the first longitudinal thread 30a and the nylon of the second longitudinal thread 30b may be different from each other in terms of, for example, the raw material, components, molecular weight, crystallization degree, thermal history, and/or machining history.
[2. Elongation Rate]
[0049] Each of the above-described differences in material would result in a difference in elongation rate. An elongation rate E1 of the first longitudinal thread 30a and an elongation rate E2 of the second longitudinal thread 30b are elongation rates when these threads are tensioned to a stress of 200 MPa. These elongation rates are measured by a tensile test machine. The test machine includes a pair of chucks. A string is wound around each chuck. Test conditions are as indicated below.
Test machine: SHIMADZU AG-Xplus 5 kN
Chuck: SHIMADZU 5 kN air capstan type, 343-23325-30
Inter-chuck distance: 210 mm
Inter-gauge mark distance: 150 mm
Tensile speed: 1 mm/sec
Plotting interval: 100 msec
Ambient temperature: 25° C.
The measurement is performed three times for each string, and the median value is used as a representative value.
[2.1 E1<E2]
[0050] The elongation rate E1 of the first longitudinal thread 30a may be less than the elongation rate E2 of the second longitudinal thread 30b. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is small. The first longitudinal thread 30a can contribute to spin performance and control performance On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is great. The second longitudinal thread 30b can contribute to rebound performance and hitting feeling. The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. In light of this, a ratio (E1/E2) is preferably less than or equal to 48/52, more preferably less than or equal to 45/55, and particularly preferably less than or equal to 43/57.
[2.2 E1>E2]
[0051] The elongation rate E1 of the first longitudinal thread 30a may be greater than the elongation rate E2 of the second longitudinal thread 30b. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is great. The first longitudinal thread 30a can contribute to rebound performance and hitting feeling. On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is small. The second longitudinal thread 30b can contribute to spin performance and control performance The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. In light of this, the ratio (E1/E2) is preferably greater than or equal to 52/48, more preferably greater than or equal to 55/45, and particularly preferably greater than or equal to 57/43.
[3. Difference in Tension]
[0052] Another example difference in specifications between the first longitudinal thread 30a and the second longitudinal thread 30b is a difference in tension. The strings are tensioned, and in the tensioned state, the strings are stretched on the head 14. A worker can adjust a tension T1 of the first longitudinal thread 30a and a tension T2 of the second longitudinal thread 30b. The first main string 34 and the second main string 40 are not integrated together. Therefore, decrease in the tension of the first longitudinal thread 30a does not cause increase in the tension of the second longitudinal thread 30b. Also, decrease in the tension of the second longitudinal thread 30b does not cause increase in the tension of the first longitudinal thread 30a. Even when the tennis racket 2 is used repeatedly, a difference in tension between the first longitudinal thread 30a and the second longitudinal thread 30b can be kept.
[3.1 T1>T2]
[0053] The tension T1 of the first longitudinal thread 30a when it is stretched on the head 14 may be greater than the tension T2 of the second longitudinal thread 30b when it is stretched on the head 14. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is small. The first longitudinal thread 30a can contribute to spin performance and control performance On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is great. The second longitudinal thread 30b can contribute to rebound performance and hitting feeling. The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. In light of this, the ratio (T1/T2) is preferably greater than or equal to 52/48, more preferably greater than or equal to 55/45, and particularly preferably greater than or equal to 57/43.
[3.2 T1<T2]
[0054] The tension T1 of the first longitudinal thread 30a when it is stretched on the head 14 may be less than the tension T2 of the second longitudinal thread 30b when it is stretched on the head 14. In this case, the amount of deformation of the first longitudinal thread 30a upon impact with a ball is great. The first longitudinal thread 30a can contribute to rebound performance and hitting feeling. On the other hand, in this case, the amount of deformation of the second longitudinal thread 30b upon impact with a ball is small. The second longitudinal thread 30b can contribute to spin performance and control performance The tennis racket 2 thus configured is well-balanced in spin performance, control performance, rebound performance, and hitting feeling. In light of this, the ratio (T1/T2) is preferably less than or equal to 48/52, more preferably less than or equal to 45/55, and particularly preferably less than or equal to 43/57.
[0055] The material of the first longitudinal thread 30a may be different from the material of the second longitudinal thread 30b, and in addition thereto, the tension T1 of the first longitudinal thread 30a may be different from the tension T2 of the second longitudinal thread 30b.
[Other Examples of Difference in Specifications]
[0056] The thickness of the first longitudinal thread 30a may be different from the thickness of the second longitudinal thread 30b. The sectional shape of the first longitudinal thread 30a may be different from the sectional shape of the second longitudinal thread 30b. The surface roughness of the first longitudinal thread 30a may be different from the surface roughness of the second longitudinal thread 30b.
[N1/N2]
[0057] On the face 12, the ratio of the number (N1) of first longitudinal threads 30a to the number (N2) of second longitudinal threads 30b (i.e., N1/N2) is preferably greater than or equal to 2/8, but less than or equal to 8/2. The tennis racket 2 having the ratio (N1/N2) of greater than or equal to 2/8 sufficiently exerts the advantages derived from the first longitudinal threads 30a. In light of this, the ratio (N1/N2) is more preferably greater than or equal to 3/7, and particularly preferably greater than or equal to 4/6. The tennis racket 2 having the ratio (N1/N2) of less than or equal to 8/2 sufficiently exerts the advantages derived from the second longitudinal threads 30b. In light of this, the ratio (N1/N2) is more preferably less than or equal to 7/3, and particularly preferably less than or equal to 6/4. In the embodiment shown in
[Arrangement]
[0058] Each first longitudinal thread 30a is preferably adjacent to one or two second longitudinal threads 30b. Each second longitudinal thread 30b is preferably adjacent to one or two first longitudinal threads 30a. The tennis racket 2 thus configured can have both the advantages of the first longitudinal threads 30a and the advantages of the second longitudinal threads 30b. When the first and second longitudinal threads are thus adjacent to each other, no other longitudinal thread is present between these longitudinal threads.
[0059] As previously described, in the embodiment shown in
[0060] In the embodiment shown in
[Specifications of Transverse Thread]
[0061] The specifications of each transverse thread 32 may be the same as the specifications of each first longitudinal thread 30a. The specifications of each transverse thread 32 may be the same as the specifications of each second longitudinal thread 30b. The specifications of the transverse thread 32 may be different from both the specifications of the first longitudinal thread 30a and the specifications of the second longitudinal thread 30b. The tennis racket 2 may include two types of transverse threads 32 having different specifications from each other.
EXAMPLES
Example 1
[0062] A tennis racket having the structure as shown in
Examples 2 to 8 and Comparative Examples 1 to 6
[0063] Tennis rackets of Examples 2 to 8 and Comparative Examples 1 to 6 were obtained in the same manner as Example 1, except that the specifications of the threads were varied as shown in Tables 1 to 3 below.
[Evaluation]
[0064] Players did a rally by using each tennis racket. The players evaluated the rebound performance (flight), spin performance, hitting feeling, and control performance of each racket. The evaluation results are shown in Tables 1 to 3 below. In Tables 1 to 3, the greater the numerical value, the higher the evaluation.
TABLE-US-00001 TABLE 1 Evaluation Results. Example 1 Example 2 Example 3 Example 4 First longitudinal thread Material polyester polyester polyester nylon Tension (lbf) 50 50 50 50 Second longitudinal thread Material nylon nylon natural natural Tension (lbf) 50 50 50 50 Transverse thread Material polyester nylon polyester nylon Tension (lbf) 50 50 50 50 Rebound 6 8 7 10 Spin 8 7 8 3 Hitting feeling 6 8 7 10 Control 8 7 8 5 Overall Evaluation 7.0 7.5 7.5 7.0
TABLE-US-00002 TABLE 2 Evaluation Results. Comparative Example 1 Example 5 Example 6 Example 7 Example 8 First longitudinal thread Material polyester polyester polyester polyester polyester Tension (lbf) 50 55 60 60 60 Second longitudinal thread Material polyester polyester polyester nylon nylon Tension (lbf) 50 45 40 40 40 Transverse thread Material polyester polyester polyester polyester nylon Tension (lbf) 50 50 50 50 50 Rebound 4 6 5 7 8 Spin 7 9 10 8 7 Hitting feeling 4 5 5 7 8 Control 8 8 9 8 7 Overall Evaluation 5.8 7.0 7.3 7.5 7.5
TABLE-US-00003 TABLE 3 Evaluation Results. Comparative Comparative Comparative Comparative Comparative Example 2 Example 3 Example 4 Example 5 Example 6 First longitudinal thread Material polyester nylon nylon polyester polyester Tension (lbf) 50 50 50 60 40 Second longitudinal thread Material polyester nylon nylon polyester polyester Tension (lbf) 50 50 50 60 40 Transverse thread Material nylon polyester nylon polyester polyester Tension (lbf) 50 50 50 50 50 Rebound 6 7 9 2 6 Spin 6 5 3 8 6 Hitting feeling 6 8 9 2 5 Control 7 6 4 7 6 Overall Evaluation 6.3 6.5 6.3 4.8 5.8
[0065] It is clear from Tables 1 to 3 that the tennis racket in each Example is well-balanced in various performances. These evaluation results clearly indicate that the present invention is superior.
[0066] The racket according to the present invention can be used in various sports, such as soft tennis, squash, and badminton.
[0067] The above descriptions are merely illustrative examples, and various modifications can be made without departing from the principles of the present invention.