Racket frame and racket

Abstract

A racket frame (100) has a face part (1) and a grip part (3) arranged in a first direction (A). The face part (1) includes a first portion (11) having a first end portion (1a) located on the opposite side of the grip part (3) in the first direction (A), and a second portion (12) having a second end portion (1b) located on the side of the grip part (3) in the first direction (A) and arranged at a distance from the first portion (11). A plurality of first through holes (21) extending in the first direction (A) and arranged at a distance from each other in a second direction (B) orthogonal to the first direction (A) are formed in the first portion (11). The plurality of first through holes (21) have a first hole (22a) closest to the center of the first portion (11) in the second direction (B) and a second hole (23a) located on the opposite side of the center with respect to the first hole (22a). In a third direction (C) intersecting the first direction (A) and the second direction (B), the width of the first hole (22a) is wider than the width of the second hole (23a).

Description

TECHNICAL FIELD

[0001] The present application relates to a racket frame and a racket. BACKGROUND

[0002] As an evaluation index of performance of a racket frame and a racket, there are spin performance and rebound performance. A racket frame for tennis with good rebound performance and spin performance is disclosed in Japanese Patent Laid-Open No. 2017-121431.

[0003] In addition, in the past, a racket frame has been known in which, when the face portion is observed in plan view, a part of the face portion is designed as a first region in which the spin performance is relatively improved, and another part of the face portion is designed as a second region in which the rebound performance is relatively improved. In the first region, the string is designed to easily move in the direction along the hitting surface at the time of hitting the ball. In the second region, the string is designed to be difficult to move in the direction along the hitting surface at the time of hitting the ball, as compared with the first region.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Laid-Open No. 2017-121431 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The main object of the present disclosure is to provide a racket frame and a racket in which the spin performance of a part of the face portion is further improved, as compared with the conventional racket frame and the racket.

[0009] TECHNICAL SOLUTION

[0010] The racket frame of the present disclosure includes a face portion and a grip portion arranged in a first direction A. The face portion includes a first portion having a first end portion located on the opposite side of the grip portion in the first direction A, and a second portion having a second end portion located on the side of the grip portion in the first direction A and arranged at an interval from the first portion. A plurality of first through holes extending in the first direction A and arranged at an interval from each other in a second direction B orthogonal to the first direction A are formed in the first portion. The plurality of first through holes have a first hole closest to the center of the first portion in the second direction B, and a second hole located on the opposite side of the center with respect to the first hole. In a third direction C intersecting the first direction A and the second direction B, the width of the first hole is wider than the width of the second hole.

[0011] EFFECT OF THE INVENTION

[0012] According to the present application, it is possible to provide a racket frame and a racket in which the spin performance of a part of the face is further improved compared to conventional racket frames and rackets. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a plan view showing a racket frame of the present embodiment.

[0014] Figure 2 is a side view of a string protector fixed to the first end portion of the face of the racket shown in Figure 1

[0015] Figure 3 is a perspective view of the string protector shown in Figure 2

[0016] Figure 4 is a perspective view of the string protector shown in Figure 3 Figure 2

[0017] Figure 5 is a plan view showing a racket of the present embodiment.

[0018] Figure 6 is a view for explaining the relationship between the racket frame and the strings in the racket shown in Figure 5

[0019] Figure 7 is a side view of a string protector fixed to the first end portion of the face of the racket shown in Figure 5

[0020] Figure 8 is a graph showing a comparison of the spin performance of each of Test Sample 1 and Test Sample 2.

[0021] Figure 9 is a graph showing a comparison of the spin performance of each of Test Sample 2 and Test Sample 3.

[0022] Figure 10 is a photograph showing an experimental system for measuring the deformation amount generated in each of the third and fourth main string portions.

[0023] Figure 11 is a graph showing the deformation amount generated in each of the third and fourth main string portions during the period from the start of applying pressure to the third and fourth main string portions to the end thereof in the experimental system shown in Figure 10 DETAILED DESCRIPTION

[0024] ​​​​​​​Hereinafter, an embodiment of the present application will be described. In addition, in the drawings below, the same reference numerals are applied to the same or equivalent portions, and the description thereof will not be repeated.

[0025] Structure of racket frame

[0026] As shown in Figure 1 , the racket frame 100 of the present embodiment has a face part 1, a shaft part 2, and a grip part 3. The face part 1, the shaft part 2, and the grip part 3 are arranged in a first direction A. The shaft part 2 is arranged between the face part 1 and the grip part 3 in the first direction A.

[0027] The material for the racket frame is, for example, CFRP (Carbon Fiber Reinforced Plastic). However, the material for the racket frame is not limited thereto. For example, GFRP (Glass Fiber Reinforced Plastic) or the like can be used.

[0028] The face part 1 has an elliptical ring shape in plan view. The long side direction of the face part 1 in plan view is along the first direction A. The short side direction in plan view is along a second direction B orthogonal to the first direction A. A third direction C orthogonal to the first direction A and the second direction B is a direction of hitting a ball by the racket 110.

[0029] The face part 1 has a first end part la and a second end part lb in the first direction A. The first end part la is an end part of the face part 1 located on the opposite side to the grip part 3 in the first direction A. The second end part lb is an end part of the face part 1 located on the grip part 3 side in the first direction A.

[0030] The face part 1 includes a first portion 11 having the first end part la and a second portion 12 having the second end part lb. The first portion 11 extends along the second direction B with the first end part la as a center. The second portion 12 extends along the second direction B with the second end part lb as a center. The second portion 12 is arranged apart from the first portion 11 in the first direction A.

[0031] The face part 1 further includes a third portion 13 and a fourth portion 14. The third portion 13 is arranged between the first portion 11 and the second portion 12, and connects one end of the first portion 11 and one end of the second portion 12. The fourth portion 14 is arranged between the first portion 11 and the second portion 12, and connects the other end of the first portion 11 and the other end of the second portion 12. The fourth portion 14 is arranged apart from the third portion 13 in the second direction B.

[0032] The first portion 11, the second portion 12, the third portion 13, and the fourth portion 14 of the face 1 each have an inner periphery 1c and an outer periphery 1d. Multiple through holes for the string to pass through are formed in the face 1. The multiple through holes open at the inner periphery 1c and the outer periphery 1d, respectively. The multiple through holes include multiple first through holes 21, multiple second through holes 24, multiple third through holes 25, and multiple fourth through holes 26, as shown below.

[0033] A plurality of first through holes 21 are formed in the first part 11. Each of the plurality of first through holes 21 extends along a first direction A and is arranged at intervals from each other in a second direction B. The detailed structure of the plurality of first through holes 21 is described later.

[0034] A plurality of second through holes 24 are formed in the second part 12. Each of the plurality of second through holes 24 is arranged at intervals from each other in the second direction B. The spacing between two adjacent second through holes 24 in the second direction B gradually widens, for example, as it moves away from the center line CL passing through the first end 1a and the second end 1b.

[0035] A plurality of third through holes 25 are formed in the third part 13. Each of the plurality of third through holes 25 is arranged at intervals from each other in the first direction A.

[0036] A plurality of fourth through holes 26 are formed in the fourth part 14. Each of the plurality of fourth through holes 26 is arranged at intervals from each other in the first direction A.

[0037] The shaft portion 2 has a first branch member 2A and a second branch member 2B. The grip portion 3 has a grip member 3A and a handle 3B. The first branch member 2A and the second branch member 2B branch off from the grip member 3A. The handle 3B is formed to cover the grip member 3A. The handle 3B is made of polyurethane, for example.

[0038] Below, refer to Figures 2-5 The multiple first through holes 21 will be described in detail. The multiple first through holes 21 are holes in the racket 110 through which the main string portion 201 of the string 200 passes.

[0039] like Figures 2-5 As shown, the racket frame 100 also includes, for example, a grommets 15 mounted on the first part 11. Figure 3 As shown, the sling 15 has a sling body 15a and a plurality of protrusions 15b. Each of the plurality of protrusions 15b protrudes relative to the sling body 15a toward the second portion 12 in a first direction A. Figures 2-5As shown, each of the plurality of first through holes 21 is formed in a plurality of protrusions 15b of the loop 15. The loop 15 protects the main string portion 201 of the string 200. Preferably, the loop 15 is separately disposed from the racket face 1. The material constituting the loop 15 is, for example, nylon resin.

[0040] like Figure 2 , Figure 3 As shown, a plurality of through holes 11a are formed in the first part 11 for inserting a plurality of protrusions 15b. Each of the plurality of through holes 11a can be inserted into each of the plurality of protrusions 15b, and can include any structure. When viewed from the first direction A, the planar shape of each of the plurality of through holes 11a is, for example, circular.

[0041] like Figure 2 As shown, each of the plurality of first through holes 21 is symmetrically arranged with respect to the center line CL (imaginary line) passing through the first end 1a and the second end 1b. The plurality of first through holes 21 includes a first hole 22a, a second hole 23a, a third hole 23b, a fourth hole 22b, a fifth hole 22c, and a sixth hole 23c, respectively disposed on one side and the other side of the second direction B with respect to the center line CL. The first hole 22a, the second hole 23a, the third hole 23b, the fourth hole 22b, the fifth hole 22c, and the sixth hole 23c are arranged to be sequentially further away from the center line CL of the first portion 11 in the order described above. Furthermore, the center line CL passes through the central axis of the grip portion 3.

[0042] The first hole 22a is located in the second direction B at the position closest to the center line CL among the plurality of first through holes 21.

[0043] The second hole 23a is disposed on the side opposite to the center line CL, relative to the first hole 22a. The second hole 23a is adjacent to the first hole 22a. The second hole 23a is disposed in the second direction B, near the center line CL of the first portion 11, among a plurality of first through holes 21.

[0044] The third hole 23b is disposed on the opposite side of the first hole 22a relative to the second hole 23a. The third hole 23b is adjacent to the second hole 23a. The third hole 23b is disposed in the second direction B at a position close to the center line CL of the first part 11.

[0045] The fourth hole 22b is positioned opposite to the second hole 23a relative to the third hole 23b. The fourth hole 22b is adjacent to the third hole 23b. The fourth hole 22b is positioned in the second direction B at a position close to the center line CL of the first part 11.

[0046] The fifth hole 22c is disposed on the side opposite the fourth hole 22b with respect to the third hole 23b. The fifth hole 22c is adjacent to the fourth hole 22b. The fourth hole 22b is disposed at a position closer to the center line CL of the first portion 11 in the second direction B.

[0047] The sixth hole 23c is disposed on the side opposite the fifth hole 22c with respect to the fourth hole 22b. The sixth hole 23c is adjacent to the fifth hole 22c. The sixth hole 23c is disposed at a position closer to the center line CL of the first portion 11 in the second direction B.

[0048] As shown in Figure 2 and Figure 3 , each of the first hole 22a and the fourth hole 22b has an elliptical shape longer in the third direction C when viewed from the first direction A. The long side direction of each of the first hole 22a and the fourth hole 22b is along the third direction C when viewed from the first direction A. The short side direction of each of the first hole 22a and the fourth hole 22b is along the second direction B when viewed from the first direction A. The fifth hole 22c has a circular shape, for example, when viewed from the first direction A.

[0049] As shown in Figure 2 and Figure 3 , each of the second hole 23a, the third hole 23b, and the sixth hole 23c has a circular shape, for example, when viewed from the first direction A.

[0050] As shown in Figure 2 , the width W1 of the first hole 22a is wider than the width W2 of the second hole 23a in the third direction C. The width of the first hole 22a may also be equal to the width of the second hole 23a, for example, in the second direction B.

[0051] As shown in Figure 2 , the width W3 of the third hole 23b is narrower than the width W4 of the fourth hole 22b in the third direction C. The width of the third hole 23b may also be equal to the width of the fourth hole 22b, for example, in the second direction B.

[0052] As shown in Figure 2 , the width W5 of the fifth hole 22c may be wider than the width W6 of the sixth hole 23c in the third direction C, and the width of the fifth hole 22c may be wider than the width of the sixth hole 23c, for example, in the second direction B.

[0053] The widths of each of the plurality of first through holes 21 may also be equal to each other, for example, in the second direction B.

[0054] In addition, the planar shape of each of the plurality of first through holes 21 viewed from the first direction A can achieve the above-described size relationship of the widths, and is not particularly limited. The planar shape of the fifth hole 22c viewed from the first direction A can also be an elliptical shape. In this case, the long side direction of the fifth hole 22c viewed from the first direction A is along the third direction C. The short side direction of the fifth hole 22c viewed from the first direction A is along the second direction B.

[0055] In the third direction C, the width of each of the first hole 22a, the fourth hole 22b, and the fifth hole 22c can also be wider than the width of each of the plurality of second through holes 24.

[0056] As shown in Figure 5 , Figure 7 , the width in the third direction C and the width in the second direction B of each of the plurality of first through holes 21 are equal to or greater than the outer diameter of the chord 200, but are preferably wider than the outer diameter of the chord 200. The width in the third direction C and the width in the second direction B of each of the plurality of first through holes 21 are narrower than the width in the third direction C and the width in the second direction B of each of the plurality of insertion through holes 11a.

[0057] As shown in Figure 2 , the distance L1 between two first holes 22a adjacent to each other in the second direction B sandwiching the center line CL is shorter than the distance L2 between the first hole 22a and the second hole 23a. In other words, in the second direction B, the distance L1 / 2 between the center line CL and the first hole 22a is shorter than half the distance L2 between the first hole 22a and the second hole 23a.

[0058] As shown in Figure 2 , in the second direction B, the distance L3 between the second hole 23a and the third hole 23b is shorter than the distance L2 between the first hole 22a and the second hole 23a. In the second direction B, the distance L4 between the third hole 23b and the fourth hole 22b is longer than the distance L3 between the second hole 23a and the third hole 23b. In the second direction B, the distance L5 between the fourth hole 22b and the fifth hole 22c is shorter than the distance L4 between the third hole 23b and the fourth hole 22b. In the second direction B, the distance L6 between the fifth hole 22c and the sixth hole 23c is longer than the distance L5 between the fourth hole 22b and the fifth hole 22c. In addition, the above-described distances L1 to L6 are distances between the centers in the second direction B of the respective holes.

[0059] <Structure of racket>

[0060] Next, the racket 110 of the present embodiment will be described with reference to Figures 5-7 . As shown in Figures 5-7As shown, the racket 110 includes the racket frame 100 and the string 200 stretched on the face portion 1 of the racket frame 100.

[0061] As shown, the string 200 passes through the plurality of first through-holes 21, the plurality of second through-holes 24, the plurality of third through-holes 25, and the plurality of fourth through-holes 26, respectively. Figure 6

[0062] The plurality of main string portions 201 extend along the first direction A between the plurality of first through-holes 21 and the plurality of second through-holes 24. The plurality of cross string portions 204 extend along the second direction B between the plurality of third through-holes 25 and the plurality of fourth through-holes 26.

[0063] The plurality of return portions 202 are configured at positions more outward than the plurality of first through-holes 21. The plurality of return portions 202 have: a first return portion 202a configured between the first hole 22a and the second hole 23a; a second return portion 202b configured between the third hole 23b and the fourth hole 22b; and a third return portion 202c configured between the fifth hole 22c and the sixth hole 23c.

[0064] In other words, the string 200 returns at positions more outward than the first hole 22a and the second hole 23a between the first hole 22a and the second hole 23a. The main string portion 201 extending from the first hole 22a along the first direction A and the main string portion 201 extending from the second hole 23a along the first direction A are connected via the first return portion 202a.

[0065] The string 200 returns at positions more outward than the third hole 23b and the fourth hole 22b between the third hole 23b and the fourth hole 22b. The main string portion 201 extending from the third hole 23b along the first direction A and the main string portion 201 extending from the fourth hole 22b along the first direction A are connected via the second return portion 202b.

[0066] The string 200 returns at positions more outward than the fifth hole 22c and the sixth hole 23c between the fifth hole 22c and the sixth hole 23c. The main string portion 201 extending from the fifth hole 22c along the first direction A and the main string portion 201 extending from the sixth hole 23c along the first direction A are connected via the third return portion 202c.

[0067] As shown, the string 200 passes through the plurality of first through-holes 21, the plurality of second through-holes 24, the plurality of third through-holes 25, and the plurality of fourth through-holes 26, respectively. Figure 6 and Figure 7 ​As shown, the plurality of turning portions 203 are positioned further outward than the plurality of second through holes 24. The plurality of turning portions 203 have: a fourth turning portion 203a disposed between the first turning portion 202a and the second turning portion 202b; and a fifth turning portion 203b disposed between the second turning portion 202b and the third turning portion 202c.

[0068] The main chord portion 201 extending from the second hole 23a along the first direction A and the main chord portion 201 extending from the third hole 23b along the first direction A are connected via the fourth fold-back portion 203a. The main chord portion 201 extending from the fourth hole 22b along the first direction A and the main chord portion 201 extending from the fifth hole 22c along the first direction A are connected via the fifth fold-back portion 203b.

[0069] The string 200 passes through two of the multiple second through holes 24 between the second hole 23a and the third hole 23b. The string 200 passes through two of the multiple second through holes 24 (the second through holes of the first group) arranged in the second direction B near the center line CL between the second hole 23a and the third hole 23b, and has the aforementioned fourth foldback portion 203a.

[0070] The string 200 passes through two of the multiple second through holes 24 between the fourth hole 22b and the fifth hole 22c. The string 200 passes through two of the multiple second through holes 24 between the fourth hole 22b and the fifth hole 22c, which are located further away from the center line CL than the second through holes of the first group (the second through holes of the second group), and has the fifth foldback portion 203b.

[0071] For example, a knot is configured in the fifth hole 22c for two strings that are connected to each other and connected in series.

[0072] like Figure 7 As shown, in the second direction B, the distance L12 between the main chord portion 201 passing through the first hole 22a and the main chord portion 201 passing through the second hole 23a is longer than the distance L11 between the main chord portions 201 passing through each of the first holes 22a.

[0073] In the second direction B, the distance L12 between the main chord portion 201 passing through the first hole 22a and the main chord portion 201 passing through the second hole 23a is longer than the distance L13 between the main chord portion 201 passing through the second hole 23a and the main chord portion 201 passing through the third hole 23b.

[0074] In the second direction B, the distance L13 between the main chord portion 201 passing through the second hole 23a and the main chord portion 201 passing through the third hole 23b is shorter than the distance L14 between the main chord portion 201 passing through the third hole 23b and the main chord portion 201 passing through the fourth hole 22b.

[0075] In the second direction B, the distance L14 between the main chord portion 201 passing through the third hole 23b and the main chord portion 201 passing through the fourth hole 22b is longer than the distance L15 between the main chord portion 201 passing through the fourth hole 22b and the main chord portion 201 passing through the fifth hole 22c.

[0076] In the second direction B, the distance L15 between the main chord 201 passing through the fourth hole 22b and the main chord 201 passing through the fifth hole 22c is shorter than the distance L16 between the main chord 201 passing through the fifth hole 22c and the main chord 201 passing through the sixth hole 23c.

[0077] like Figure 5 As shown, a first region R1 and a second region R2 are formed on the racket face 1 of the racket 110. The first region R1 is located in the second direction B, closer to the first portion 11 than the center of the racket face 1. The second region R2 includes the center of the racket face 1 in the second direction B. Compared to the second region R2, the first region R1 is closer to the first portion 11. Therefore, compared to the spin and rebound performance when hitting the ball in the second region R2, the spin and rebound performance when hitting the ball in the first region R1 are more easily affected by the structure of the multiple first through holes 21.

[0078] There are no particular restrictions on the method of setting the main string 201 to the racket face 1 of the racket frame 100. Below, an example of the method for setting the main string 201 will be explained.

[0079] For example, Figure 6 As indicated by the arrows, the string 200 first passes from the outside to the inside through the hole closest to the center line CL among the plurality of second through holes 24. Next, the string 200 passes from the inside to the outside through the first hole 22a (see reference). Figure 2 and Figure 7 Then it folds back at the outer side (first folding part 202a), and passes through the second hole 23a from the outside to the inside (see reference). Figure 2 and Figure 7 ).

[0080] Next, after the string 200 passes through the second hole near the center line CL among the plurality of second through holes 24 from the inside to the outside, it folds back at the outside (fourth fold-back portion 203a) and passes through the third hole near the center line CL among the plurality of second through holes 24 from the outside to the inside. Then, the string 200 passes through the third hole 23b from the inside to the outside (see...). Figure 2 and Figure 7 After that, it folds back at the outer side (second folding-back portion 202b) and passes through the fourth hole 22b from the outside towards the inside (see reference). Figure 2 and Figure 7 ).

[0081] Next, after the string 200 passes through the fourth hole from the inside toward the outside of the plurality of second through holes 24, which is close to the center line CL, it is turned back at the outside (fifth turn-back portion 203b) and passes through the fifth hole from the outside toward the inside of the plurality of second through holes 24. Next, after the string 200 passes through the fifth hole 22c (refer to Figure 2 and Figure 7 ) from the inside toward the outside, it is turned back at the outside (third turn-back portion 202c) and passes through the sixth hole 23c (refer to Figure 2 and Figure 7 ) from the outside toward the inside.

[0082] Next, the string 200 passes through the sixth hole from the inside toward the outside of the plurality of second through holes 24, which is close to the center line CL. In this way, the string 200 passes through the plurality of first through holes 21 and the plurality of second through holes 24 in such a manner that the first turn-back portion 202a, the fourth turn-back portion 203a, the second turn-back portion 202b, the fifth turn-back portion 203b, and the third turn-back portion 202c are sequentially formed, thereby enabling the plurality of main string portions 201 to be formed.

[0083] In addition, the string 200 can be stretched in the first direction A in reverse to the above-described stretching method. The prepared string 200 can first pass through the first hole 22a from the outside toward the inside, and then pass through the hole from the inside toward the outside of the plurality of second through holes 24, which is closest to the center line CL.

[0084] Next, an embodiment of the racket frame 100 and the racket 110 of the present embodiment will be described.

[0085] Example 1

[0086] In the present example, the spin performance of the racket frames of samples 1 to 3, in which the structures of the plurality of first through holes are different from each other, were evaluated.

[0087] (Samples 1 to 3)

[0088] As a comparative example, the racket frame of sample 1 was formed so that the intervals of the second direction B of each of the plurality of first through holes were equal to each other, and the widths of the third direction C of each of the plurality of first through holes were equal to each other.

[0089] The racket frame of sample 2 was formed so that the intervals of the second direction B of each of the plurality of first through holes were equal to each other, but the distance between the two first holes sandwiching the center line CL in the second direction B was shorter than the distance between the first hole and the second hole.

[0090] The sample 3 is a racket frame 100. That is, the sample 1 differs from the sample 3 only in that the intervals of the second directions B of the plurality of first through holes are equal to each other and the widths of the third directions C of the plurality of first through holes are equal to each other. The sample 2 differs from the sample 3 only in that the intervals of the second directions B of the plurality of first through holes are equal to each other. The sample 2 differs from the sample 1 only in that the distance between the two first holes adjacent to the center line CL in the second direction B is shorter than the distance between the first hole and the second hole.

[0091] In the sample 3, in the second direction B, the distance between the principal chord passing through the first hole and the principal chord passing through the second hole is longer than the distance between the principal chord passing through the second hole and the principal chord passing through the third hole.

[0092] (Evaluation method)

[0093] A tennis ball emitted from a tennis ball launcher collides with the above-mentioned first region of the racket whose grip portion is fixed to a jig, and the number of rotations of the spin of the tennis ball bounced back by the collision is measured. The tennis ball launcher emits the tennis ball in such a manner that the center of the tennis ball overlaps the above-mentioned center line. The direction in which the tennis ball launcher emits the tennis ball is set so as to be orthogonal to the above-mentioned center line of the racket, and the inclination angle of the emission direction with respect to the above-mentioned second direction B of the racket is 15 degrees or 30 degrees. A hard tennis ball is used as the tennis ball. A high-speed camera is used in the measurement of the number of rotations of the spin.

[0094] (Evaluation results)

[0095] Figure 8 is a graph in which the evaluation results of the sample 1 and the sample 2 are compared. Figure 9 is a graph in which the evaluation results of the sample 2 and the sample 3 are compared.

[0096] As shown in Figure 8 , the number of rotations of the spin of the tennis ball bounced back from the sample 2 is greater than that of the tennis ball bounced back from the sample 1 regardless of the above-mentioned inclination angle. The number of rotations of the spin of the tennis ball bounced back from the sample 2 is 17% greater than that of the tennis ball bounced back from the sample 1 when the above-mentioned inclination angle is 15 degrees. The number of rotations of the spin of the tennis ball bounced back from the sample 2 is 6% greater than that of the tennis ball bounced back from the sample 1 when the above-mentioned inclination angle is 30 degrees.

[0097] Generally, the spin is more likely to occur when the above-mentioned inclination angle is 30 degrees than when the above-mentioned inclination angle is 15 degrees. That is, it is confirmed that even the sample 1, under the condition of the above-mentioned inclination angle of 30 degrees in which the spin is more likely to occur, the spin performance of the sample 2 is higher than that of the sample 1.

[0098] As shown in Figure 9As shown, even under the aforementioned hitting condition with an inclination angle of 30 degrees, which easily generates spin, the number of spins of the tennis ball rebounding from sample 3 is greater than that of the tennis ball rebounding from sample 2. Under the aforementioned hitting condition with an inclination angle of 30 degrees, the number of spins of the tennis ball rebounding from sample 3 is 7% greater than that of the tennis ball rebounding from sample 2.

[0099] That is, it was confirmed that even under the aforementioned hitting condition with a tilt angle of 30 degrees, which easily generates spin, the spin performance of sample 3 is higher than that of sample 2. Furthermore, these results confirm that the spin performance of sample 3 is higher than that of sample 1.

[0100] <Example 2>

[0101] In this embodiment, the deformation characteristics of the first region of the racket of the above-mentioned sample 3 were evaluated.

[0102] (Evaluation Method)

[0103] First, in sample 3, from the third hole 23b and the fourth hole 22b (refer to...) Figure 2 and Figure 7 Each of the two main chord portions 201 extending along the first direction A is equipped with a strain sensor. The strain sensor in each main chord portion 201 is positioned between the portion where each of the third hole 23b and the fourth hole 22b intersects with the cross chord portion 204 closest to the first end 1a in the second direction B. Furthermore, as described above, each main chord portion 201 is composed of a single chord and is folded back by the second fold-back portion 202b.

[0104] Next, as Figure 10 As shown, in the first region of the specimen 3, which is fixed in the third direction C, a hemispherical indenter with an outer diameter equal to that of a tennis ball is pressed along the third direction C to evaluate the changes in deformation from the start to the end of the pressing. The indenter is positioned such that its top overlaps with the midpoint of the second direction B of the two main chord portions 201 in the first region along the third direction C. That is, the two main chord portions 201 are pressed by the indenter under the same conditions.

[0105] Figure 11 This is a chart representing the above evaluation results. Figure 11 The horizontal axis represents the time from the start of the encounter to the end (in milliseconds). Figure 11 The vertical axis represents the amount of deformation. Figure 11 In the diagram, line segment D represents the deformation of the main chord portion 201 extending from the third hole 23b along the first direction A. Figure 11 The line segment E in the figure represents the deformation of the main chord 201 extending from the fourth hole 22b along the first direction A.

[0106] As Figure 11 shown, it is confirmed that there is a time difference Δt between the main chord portion 201 extending from the fourth hole 22b and the main chord portion 201 extending from the third hole 23b before the deformation is started. The width W4 of the third direction C of the fourth hole 22b is wider than the width W3 of the third direction C of the third hole 23b. Therefore, the main chord portion 201 extending from the fourth hole 22b is more easily moved in the third direction C than the main chord portion 201 extending from the third hole 23b. Since the two main chord portions 201 start to be deformed after being moved in the third direction C, respectively, the above-mentioned time difference Δt is considered to be generated due to the difference in the easiness of the movement in the third direction C between the two main chord portions 201.

[0107] Further, as Figure 11 shown, it is confirmed that there is a maximum deformation amount difference ΔST between the main chord portion 201 extending from the fourth hole 22b and the main chord portion 201 extending from the third hole 23b. Further, before the deformation amount of each main chord portion 201 reaches the maximum, the deformation amount of the main chord portion 201 extending from the fourth hole 22b is always less than that of the main chord portion 201 extending from the third hole 23b. The movement of each main chord portion 201 in the third direction C is realized by a part of the force applied to each main chord portion 201, and the deformation of each main chord portion 201 is realized by the remaining part of the force applied to each main chord portion 201. Therefore, the deformation amount difference at the prescribed time and the above-mentioned maximum deformation amount difference ΔST are also considered to be generated due to the difference in the easiness of the movement in the third direction C between the two main chord portions 201.

[0108] The above-mentioned time difference Δt is formed between the two main chord portions 201 connected via the second return portion 202b, so that the two main chord portions 201 are easily moved in the first direction A within the time from being pressed in the third direction C to the time at the above-mentioned time difference Δt. Further, the deformation amount difference at the prescribed time and the above-mentioned maximum deformation amount difference ΔST are formed between the two main chord portions 201 connected via the second return portion 202b, so that the two main chord portions 201 are easily moved in the first direction A within the time from being pressed in the third direction C to no longer being pressed.

[0109] As a result, for example, the main cord portion 201 extending from the fourth hole 22b is stretched to the side of the main cord portion 201 extending from the third hole 23b, and easily moves to the first portion 11 side in the first direction A. When the two main cord portions 201 move as described above, a tennis ball colliding with the two main cord portions 201 in the above-described first region easily generates spin. This effect can be achieved not only between the two main cord portions 201 extending from each of the third hole 23b and the fourth hole 22b, but also between the two main cord portions 201 extending from each of the first hole 22a and the second hole 23a, and between the two main cord portions 201 extending from each of the fifth hole 22c and the sixth hole 23c.

[0110] The inventors believe that, according to the above reasons examined from the evaluation results of the present embodiment 2, the spin performance of the present embodiment 1 is improved by 7% compared to the case where the interval in the second direction B and the width in the third direction C of each first through-hole are equal to each other (sample 1 of the present embodiment 1) and the case where the interval in the second direction B of each first through-hole is different from each other but the width in the third direction C of each first through-hole is equal to each other (sample 2 of the present embodiment 1). Figure 9

[0111] <Effects>

[0112] Next, based on the above-described embodiment 1 and embodiment 2, the effects of the racket frame and the racket of the present embodiment are described.

[0113] The racket frame 100 includes the face portion 1 and the grip portion 3 arranged in the first direction A. The face portion 1 includes the first portion 11 having the first end portion 1a located on the opposite side to the grip portion 3 in the first direction A, and the second portion having the second end portion 1b located on the grip portion 3 side in the first direction A and arranged at an interval from the first portion 11. A plurality of first through-holes 21 extending in the first direction A and arranged at an interval from each other in a second direction B orthogonal to the first direction A are formed in the first portion 11. The plurality of first through-holes 21 have a first hole 22a closest to the center of the first portion 11 in the second direction B, and a second hole 23a located on the opposite side to the center with respect to the first hole 22a. In a third direction C intersecting the first direction A and the second direction B, the width of the first hole 22a is wider than the width of the second hole 23a.

[0114] As described in the above-described embodiment 1, the inventors found that, in the racket frame 100 including the above-described structure (sample 3 of the above-described embodiments 1 and 2), the spin performance was improved by 7% compared to the case where the interval in the second direction B and the width in the third direction C of each first through-hole are equal to each other (sample 1 of the above-described embodiment 1) and the case where the interval in the second direction B of each first through-hole is different from each other but the width in the third direction C of each first through-hole is equal to each other (sample 2 of the above-described embodiment 1).

[0115] ​In the racket frame 100 described above, in the second direction B, the distance L1 / 2 between the center line CL and the first hole 22a is shorter than half the distance L2 between the first hole 22a and the second hole 23a. That is, the distance L1 is shorter than the distance L2.

[0116] The present inventors found that, as described in the above-described Example 1, in the case where the distance L1 / 2 between the center line CL and the first hole 22a in the second direction B is shorter than half the distance L2 between the first hole 22a and the second hole 23a (Sample 2 in the above-described Example 1), the spin performance is improved by 6% compared to the case where the distance L1 / 2 between the center line CL and the first hole 22a in the second direction B is equal to half the distance L2 between the first hole 22a and the second hole 23a (Sample 1 in the above-described Example 1).

[0117] In this regard, the longer the distance between two main cord portions 201 adjacent in the second direction B in the above-described first region R1, the more easily the relative positional relationship between the two main cord portions 201 and a tennis ball when the tennis ball is hit in the above-described first region R1 differs, and the more easily the force applied to the two main cord portions 201 when the tennis ball is hit differs. The longer the distance in the second direction B between the two main cord portions 201 connected via the turnaround portion 202, the greater the difference in the above-described force between the two main cord portions 201, and the more easily the two main cord portions 201 move toward one side in the first direction A. As a result, the tennis ball colliding with the two main cord portions 201 easily generates spin. That is, the longer the distance L2, the more easily the tennis ball colliding with the main cord portion 201 passing through the first hole 22a and the main cord portion 201 passing through the second hole 23a generates spin.

[0118] On the other hand, the main cord portion 201 passing through each first hole 22a is not connected via the turnaround portion 202, and even if the distance L1 described above becomes longer, the main cord portion 201 passing through each first hole 22a does not easily move in the first direction A. If the distance L1 described above is shorter than the distance L2 described above, the distance L2 described above can correspondingly become longer. That is, if the distance L1 described above is shorter than the distance L2 described above, the spin performance of the racket frame 100 can be effectively improved.

[0119] In the racket frame 100 described above, the plurality of first through-holes 21 further have a third hole 23b located on the opposite side from the first hole 22a with respect to the second hole 23a and a fourth hole 22b located on the opposite side from the first hole 22a with respect to the third hole 23b. In the third direction C, the width W4 of the fourth hole 22b is wider than the width W3 of the third hole 23b.

[0120] In such a racket frame 100, in the first region R1, a higher spin performance can be exerted when hitting a ball by the two main string portions 201 extending from each of the first hole 22a and the second hole 23a, when hitting a ball by the two main string portions 201 extending from each of the third hole 23b and the fourth hole 22b, and when hitting a ball by the four main string portions 201 extending from each of the first hole 22a to the fourth hole 22b. Therefore, in the above-described racket frame 100, the above-described first width W1 is wider than the above-described second width W2, but compared with the structure in which the above-described fourth width W4 is equal to the above-described third width W3, the region in which a higher spin performance can be exerted is wider.

[0121] In the above-described racket frame 100, in the second direction B, the distance L3 between the second hole 23a and the third hole 23b is shorter than the distance L2 between the first hole 22a and the second hole 23a and the distance L4 between the third hole 23b and the fourth hole 22b.

[0122] If the above-described distance L3 is shorter than the above-described distance L2 and the above-described distance L4, a spin performance of the racket frame 100 can be effectively improved for the same reason as in the case in which the above-described distance L1 is shorter than the above-described distance L2.

[0123] The racket 110 includes: a racket frame 100; and a string 200, the string 200 being strung on the face portion 1 and including a plurality of main string portions extending in the first direction A between the first portion 11 and the second portion 12. The string 200 passes through a plurality of first through holes 21 and is turned back (a first turn-back portion 202a) at a position more outward than the first hole 22a and the second hole 23a between the first hole 22a and the second hole 23a.

[0124] The above-described racket 110 includes the racket frame 100 and can exert the same effects as the racket frame 100.

[0125] In the above-described racket 110, in the second direction B, the distance between the main string portion passing through the first hole 22a and the main string portion passing through the second hole 23a is longer than the distance between the main string portion passing through the second hole 23a and the main string portion passing through the third hole 23b.

[0126] It should be considered that the embodiments disclosed this time are illustrative in all respects and are not limitative. The scope of the present application is indicated by the claims rather than the above-described embodiments, and is intended to include all modifications equivalent in meaning and scope to the claims.

[0127] Explanation of Symbols

[0128] 1 racket, 1a first end portion, 1b second end portion, 1c inner circumference, 1d outer circumference, 2 shaft portion, 2A first branch member, 2B second branch member, 3 grip portion, 3A grip member, 3B handle, 11 first portion, 11a insertion through hole, 12 second portion, 13 third portion, 14 fourth portion, 15 grommet, 15a grommet body, 15b protrusion, 21 first through hole, 22a first hole, 22b fourth hole, 22c fifth hole, 23a second hole, 23b third hole, 23c sixth hole, 24 second through hole, 25 third through hole, 26 fourth through hole, 100 racket frame, 110 racket, 200 string, 201 main string portion, 202, 203 return portion, 202a first return portion, 202b second return portion, 202c third return portion, 203a fourth return portion, 203b fifth return portion, 204 cross string portion.

Claims

1. A racket frame, The racket frame includes a racket face and a grip portion arranged along a first direction. The clapping surface includes a first portion and a second portion. The first portion has a first end located on the side opposite to the grip portion in the first direction. The second portion has a second end located on the side of the grip portion in the first direction. The second portion is configured to be spaced apart from the first portion. The first portion has a plurality of first through holes that extend along the first direction and are spaced apart from each other in a second direction orthogonal to the first direction. The plurality of first through holes have two first holes located at the point closest to the center line passing through the first end and the second end, and two second holes located on either side of the two first holes in the second direction. In a third direction intersecting the first and second directions, the width of each of the two first holes is wider than the width of each of the two second holes. In the second direction, the distance between the centerline and each of the two first holes is shorter than half the shortest distance between the two first holes and the two second holes.

2. The racket frame as described in claim 1, characterized in that, The second portion has a plurality of second through holes that extend along the first direction and are spaced apart from each other in the second direction. In the third direction, the width of each of the two first holes is wider than the width of each of the plurality of second through holes.

3. A racket frame, The racket frame includes a racket face and a grip portion arranged along a first direction. The clapping surface includes a first portion and a second portion. The first portion has a first end located on the side opposite to the grip portion in the first direction. The second portion has a second end located on the side of the grip portion in the first direction. The second portion is configured to be spaced apart from the first portion. The first portion has a plurality of first through holes that extend along the first direction and are spaced apart from each other in a second direction orthogonal to the first direction. The plurality of first through holes have two first holes located at the point closest to the center line passing through the first end and the second end, and two second holes located on either side of the two first holes in the second direction. In a third direction intersecting the first and second directions, the width of each of the two first holes is wider than the width of each of the two second holes. The plurality of first through holes further comprises: two third holes located on the opposite side of the two first holes relative to the two second holes; and two fourth holes located on the opposite side of the two first holes relative to the two third holes. In the third direction, the width of each of the two fourth holes is wider than the width of each of the two third holes. In the second direction, the distance between the two second holes and the two third holes is shorter than the shortest distance between the two first holes and the two second holes, and the shortest distance between the two third holes and the two fourth holes.

4. The racket frame as described in claim 3, characterized in that, The second portion has a plurality of second through holes that extend along the first direction and are spaced apart from each other in the second direction. In the third direction, the width of each of the two first holes is wider than the width of each of the plurality of second through holes.

5. A racket frame, The racket frame includes a racket face and a grip portion arranged along a first direction. The clapping surface includes a first portion and a second portion. The first portion has a first end located on the side opposite to the grip portion in the first direction. The second portion has a second end located on the side of the grip portion in the first direction. The second portion is configured to be spaced apart from the first portion. The first portion has a plurality of first through holes that extend along the first direction and are spaced apart from each other in a second direction orthogonal to the first direction. The plurality of first through holes have two first holes located at the point closest to the center line passing through the first end and the second end, and two second holes located on either side of the two first holes in the second direction. In a third direction intersecting the first and second directions, the width of each of the two first holes is wider than the width of each of the two second holes. The second portion has a plurality of second through holes that extend along the first direction and are spaced apart from each other in the second direction. In the third direction, the width of each of the two first holes is wider than the width of each of the plurality of second through holes.

6. A racket, comprising: The racket frame according to any one of claims 1 to 5; as well as A string, which is stretched on the racket face, and includes a plurality of main string portions extending along the first direction between the first portion and the second portion. The string passes through a plurality of the first through holes and folds back between the first hole and the second hole on one or the other side of the second direction relative to the center line at a position further outward than the first hole and the second hole.

7. A racket, comprising: The racket frame as described in claim 3; as well as A string, which is stretched on the racket face, and includes a plurality of main string portions extending along the first direction between the first portion and the second portion. The string passes through a plurality of the first through holes, and between the first hole and the second hole on one or the other side of the second direction relative to the center line, it folds back at a position further outward than the first hole and the second hole. The string passes through two of a plurality of second through holes between the second hole and the third hole, which are located on one side or the other side of the second direction relative to the center line.

8. A racket, comprising: A face-tapping device, wherein the face-tapping surfaces are arranged along a first direction; Holding part; as well as The string has multiple main string sections, which are stretched on the racket face and extend along the first direction between a first section and a second section. The clapping surface includes a first portion and a second portion. The first portion has a first end located on the side opposite to the grip portion in the first direction. The second portion has a second end located on the side of the grip portion in the first direction. The second portion is configured to be spaced apart from the first portion. The first portion has a plurality of first through holes that extend along the first direction and are spaced apart from each other in a second direction orthogonal to the first direction. The plurality of first through holes have: two first holes located at the portion closest to the center line passing through the first end and the second end; and two second holes located on either side of the two first holes in the second direction; Two third holes located on the opposite side of the two first holes relative to the two second holes; and two fourth holes located on the opposite side of the two first holes relative to the two third holes. In a third direction intersecting the first and second directions, the width of each of the two first holes is wider than the width of each of the two second holes. The string passes through multiple of the first through holes. In the second direction, the shortest distance between the main chord portion passing through each of the two first holes and the main chord portion passing through each of the two second holes is longer than the shortest distance between the main chord portion passing through each of the two second holes and the main chord portion passing through each of the two third holes.

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