JP2726229B2 - racket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket which is used by stretching a gut such as a tennis racket, a badminton racket, and a squash racket, and more particularly to a rebound when hit at a part other than the center of the gut surface of the racket. And a reduction in impact, and an improvement in controllability when a ball is hit at the center of the gut surface.

[0002]

2. Description of the Related Art In general, in a racket such as a tennis racket, a gut pattern (gut pattern) is such that the closer the center of a gut-stretched surface (gut surface), the closer the gap between adjacent guts (actual). See No. 61-4665),
At any position on the gut surface, the force (surface pressure) required to apply a constant displacement in a direction perpendicular to the gut surface (out-of-plane direction) is set substantially constant.

[0003]

In the case where the surface pressure distribution on the gut surface is substantially constant, portions other than the central portion of the gut surface have substantially the same surface pressure as the central portion of the gut surface. If the ball is hit at a part other than the part, the resilience function is poor, and the impact is easily transmitted to the player's hand holding the racket, which makes the player feel uncomfortable. Also, here, if the tension of the gut is lowered to reduce the impact transmitted to the hand when hitting at a part other than the center of the gut surface, the surface pressure distribution on the gut surface is almost constant, The surface pressure at the center of the surface is also reduced.

When the surface pressure of the gut surface is substantially constant,
Since the surface pressure near the central portion of the gut surface is not sufficient, desired controllability cannot be obtained when the ball is hit at the central portion of the gut surface. Also, here, in order to improve the control performance at the center of the gut surface, if the tension of the gut is increased, the surface pressure distribution on the gut surface is almost constant,
The surface pressure of the portion other than the central portion of the gut surface also increases, and the impact transmitted to the player's hand when hitting the ball at a portion other than the central portion of the gut surface increases.
As described above, there is no racket that satisfies both the control performance when hitting near the center of the gut surface and the resilience performance and hit feeling when hitting other than the center.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems in the conventional racket, and has an improved rebound function when hitting at a portion other than the center of the gut surface. The purpose of the present invention is to improve control performance and shot feeling when hit at the center of the surface.

[0006]

Therefore, according to the present invention, a first boundary line is set on both sides in the longitudinal direction from the center point of the gut surface at a position of 2/15 of the total length in the longitudinal direction, and The central portion of the gut surface sandwiched between the one boundary line is defined as a first region in the long axis direction, and the second portion is located at a position ／ of the total length in the long axis direction from the center point.
A boundary line is set, a region sandwiched between the first boundary line and the second boundary line is defined as a second region in the major axis direction, and an intersection of a major axis gut and a minor axis gat in the first major axis direction region The ratio between the average value of the length of the mesh formed in the long axis direction and the average value of the length of the mesh in the second long axis direction in the long axis direction is set to 0.3 to 0.6. A third boundary line is set at one-fifth of the total length in the short axis direction on both sides in the short axis direction from the center point of the gut surface, and a central portion of the gut surface sandwiched between the third boundary lines Is defined as the first region in the short axis direction, a fourth boundary line is set at a position 2/5 of the total length in the short axis direction from the center point, and the region sandwiched between the third boundary line and the fourth boundary line is defined as a short region. An axial second region, an average value of the short-axis direction lengths of the meshes in the short-axis first region, and a short-axis direction mesh length in the short-axis second region. The ratio of the difference between the average value 0.3 to 0.6
The racket is characterized in that it is set to:

[0007] The racket of the present invention having the above structure is
Because the surface pressure increases as you approach the center of the gut surface and decreases as you approach the periphery, when hitting at a part other than the center of the gut surface, the deformation of the gut compared to the center of the gut surface Large amount and good resilience make it difficult for unpleasant impact to be transmitted to the player.

Further, in the racket of the present invention, when the ball is hit near the central portion of the gut surface, the surface pressure at the central portion is higher than that at the peripheral portion and the rigidity is sufficient, so that good controllability can be obtained. .

[0009]

As a result of various experiments and studies, the present inventor has found that vibration when hitting the ball at a position other than the center of the gut surface is reduced, and good controllability is obtained when the ball is hit at the center of the gut surface. I found a gut pattern that I can do.

FIG. 1 and FIG. 2 show a racket according to the present invention having the above-mentioned gut pattern. This racket 1
Then, the gut J in the short axis X direction and the gut K in the long axis Y direction are inserted into a plurality of gut holes provided in the gut extension 2a of the frame 2.
To form the gut surface 4. This gut surface 4
In the above, the adjacent long-axis gut K and the short-axis direction gut J form a plurality of rectangular meshes M having a length of 1 in the long axis Y and a length of m in the short axis.

As shown in FIG. 1, the center point O of the
2/1 of the total length L in the long axis Y direction on both sides in the long axis Y direction
The first boundary lines P1 and P1 are set at the position 5 and the central portion 4a of the racket sandwiched between the first boundary lines P1 and P1 is defined as a first region A1 in the long axis direction. Also, the second boundary lines P2 and P2 are set at a position ２ of the total length L in the major axis Y direction from the center point O, and the region between the first boundary line P1 and the second boundary line P2 is defined as the major axis. The direction is defined as a second region A2. Then, the average value l ₁ of the length of the mesh M in the major axis direction Y in the major axis direction first region A1.
And the major axis Y of the mesh M in the major axis direction second region A2.
The ratio of the length in the direction to the average value l ₂ (l ₁ / l ₂ ) is set to 0.3 or more and 0.6 or less. That is, in the racket 1 according to the present invention, 0.3 ≦ l ₁ / l ₂ ≦ 0.6.

As shown in FIG. 2, third boundary lines P3 and P3 are formed on both sides in the short axis X direction from the center point O of the gut surface 4 at １ ／ of the total length W in the short axis X direction. Set the third
The central portion 4a of the racket sandwiched between the boundary lines P3 and P3 is defined as a first short-axis direction region B1. Also, from the center point O to the short axis X
The fourth boundary lines P4 and P4 are set at a position 2/5 of the total length W in the direction, and an area between the third boundary line P3 and the fourth boundary line P4 is defined as a second short-axis direction area B2. The average value m ₁ of the length of the mesh M in the short axis direction first region B1 in the short axis X direction is the average value m ₁ of the length of the mesh M in the short axis direction second region B2 in the short axis X direction. the ratio of ₂ (m ₁ / m ₂₎ 0.3
The value is set to not less than 0.6 and not more than 0.6. That is, in the racket 1 according to the present invention, 0.3 ≦ m ₁ / m ₂ ≦ 0.6.

Further, the racket 1 has a gut surface 4
The length l of the mesh M in the long-axis direction and the length m of the short-axis walking gradually increase from the central portion 4a including the sweet spot to the peripheral portion 4b of the gut surface 4 near the gut extension 2a. It is set to be.

In the racket 1 of the present invention having such a gut pattern, the surface pressure increases as the position approaches the central portion 4a of the gut surface 4, and decreases as the position approaches the peripheral portion 4b. Therefore, in the racket 1, when a ball is hit at a portion other than the central portion of the gut surface, since the surface pressure at this portion is lower than that at the central portion of the gut surface, the amount of change in gut J and K is large, and As is clear, the resilience is good, and an unpleasant impact is hardly transmitted to the player, so that a good shot feeling can be obtained.

In the racket 1, when the ball is hit with a sweet spot, the surface pressure of the central portion 4a is higher than that of the peripheral portion and the rigidity is sufficient, so that good controllability is obtained.

FIGS. 3 and 4 show a first embodiment of the present invention. The racket 1A according to the first embodiment is a tennis racket which is used by stretching a gut on the gut extension 2a of the frame 2.

In the first embodiment, the gut extending portions 2a of the frame 2 are provided with guts J ₁ , J ₂ ,... J ₁₇ , J ₁₈ in the short axis X direction.
The horizontal for string holes _{a 1, a 2 ... a 17} , a 18 and _{b 1, b 2 ... b 17} , b 18 are provided for tensioning the. Here, the horizontal gut holes a ₁ , a ₂ ... A ₁₇ and a ₁₈ and the horizontal gut holes b ₁ , b ₂ .
_17, Gut J ₁ face each other in the direction of the minor axis X in holes denoted by the same subscript of _{b 18, J 2 ... J 17} , J 18 is inserted.

In the gut extending portion 2a of the frame 2, vertical gut holes c ₁ , c ₂ for extending guts K ₁ , K ₂ ,... K ₁₅ , K ₁₆ in the long axis Y direction. c ₁₅ , c ₁₆ and d ₁ , d ₂ ... d ₁₅ , d ₁₆ are provided. Here, vertical gut holes c ₁ , c ₂ ... C ₁₅ and c ₁₆ and vertical gut holes d ₁ , d ₂ .
_15, gut K ₁ hole denoted by the same subscript are opposed to each other in the axial direction one of the _{d 16, K 2 ... K 15} , K 16 is inserted.

The stretched guts J ₁ , J ₂ ... J ₁₇ , J ₁₈ ,
The total length W in the short axis X direction of the gut surface 4 formed by K ₁ , K ₂ ... K ₁₅ , K ₁₆ is 240 mm, and the total length L in the long axis Y direction is 32.
0 mm.

[0020] In this racket 1A, the top portion 2b of the front end portion 4c and the spacing of the gut J ₁ GATT surface 4, the distance between adjacent of the short axis direction gut _{J 1, J 2 ... J 17} , J 18 and, gut J ₁₈ and the horizontal for string holes a ₁ so that the distance between the end portion 4d of the yoke portion 2c side of the gut surface 4 is each distance shown in table _{1, a 2 ... a 17,} a 18 and b _1, b ₂ ... b ₁₇ , b
₁₈ are arranged.

[0021]

[Table 1]

In this racket 1A, the gut surface 4
Left end portion 4f and the distance between the gut K ₁ of gut K ₁ of the adjacent longitudinally, K ₂ ... K _15, the distance between K _16, gut K ₁₆
The vertical gut holes c ₁ , c ₂ ... C ₁₅ , c so that the distance between the gut surface 4 and the right end 4 e of the gut surface 4 is the distance shown in Table 2 below.
₁₆ and d ₁ , d ₂ ... D ₁₅ , d ₁₆ are arranged.

[0023]

[Table 2]

For this reason, in the first embodiment, the first boundary lines P1, P1 are set at 2 / 15L on both sides in the long axis Y direction from the center point O of the gut surface 4, and the first boundary lines P1, P1 Is defined as a first region A1 in the major axis direction, and the second boundary line P is located at a distance of 2 / 5L from the center point O on both sides in the major axis Y direction.
2, P2 is set, and a region sandwiched between the first boundary line P1 and the second boundary line P2 is defined as a second region A2 in the long axis direction. The average length l ₁ and the mesh M in the second region A2 in the long axis direction
The ratio (l ₁ / l ₂ ) to the average value l ₂ of the length in the major axis Y direction is 0.512.

Further, third boundary lines P3 and P3 are set at 1/5 W from the center point O of the gut surface 4 to both sides in the direction of the short axis X, and a portion sandwiched between the third boundary lines P3 and P3 Is defined as the first region B1 in the minor axis direction, and the fourth boundary lines P4 and P4 are set at 2/5 W from the center point O to both sides in the minor axis X direction.
Assuming that a region sandwiched between the boundary line P3 and the fourth boundary line P4 is a short-axis second region B2, an average value m ₁ of the length of the mesh M in the short-axis X direction in the short-axis first region B1; The ratio (m ₁ / m ₂ ) of the length of the mesh M in the minor axis X direction in the minor axis direction second region B2 to the average value m ₂ is 0.59.

Further, in the first embodiment, the length l of the mesh M in the major axis direction increases from the central portion 4a toward the peripheral portion 4b.
And the length m in the short axis direction is set to be gradually increased.

Since the racket 1A of the first embodiment has the gut pattern as described above, the center portion 4 of the gut surface 4 is formed.
a is high, while the surface pressure of the peripheral portion 4b is low. FIG.
Racket 1A of the first embodiment measured with the measuring device of (A)
6 and 7 are shown in FIGS.

In FIG. 5 (A), reference numeral 10 denotes a universal compression / tensile testing machine, in which a column-shaped jig 12 having a diameter of 22 mm is attached to the end of a load frame 11 which moves vertically.
The racket 1A has eight gut-stretched portions 2a of the frame 2 fixed on a fixed base 13.

The load frame 11 is moved downward in the figure, the jig 12 is pressed against the gut surface 4, and the reaction force value of the gut surface 4 is detected by the load cell 14. The detected reaction force value and the displacement of the jig 12 from the state where the jig 12 is brought into contact with the gut surface 4 with a reaction force of 0 are input to the XY printer 16 via the controller 15, and as shown in FIG. , The horizontal axis represents the displacement, and the vertical axis represents the reaction force.

FIG. 6 shows the surface pressure (the reaction force when the gut surface 4 is displaced by 5 mm) when the distance from the top portion 4c is varied on the long axis Y. At this time, the warp yarn 5
51b and weft 441b. FIG. 7 shows the surface pressure when the distance from the right end 4e of the gut surface 4 is varied on the short axis.

As is clear from FIG. 6, in the racket 1A of the first embodiment, the surface pressure is about 17.8 kg at the central part 4a of the gut surface 4, whereas the tip part 4c on the top part 2b side. The weight is about 15.8 kg on the side and grip side.

As described above, in the racket 1A of the first embodiment, the surface pressure increases as the position approaches the central portion 4a of the gut surface, and decreases as the position approaches the peripheral portion 4b. Therefore, even if the racket 1A is hit at a position other than the central portion of the gut surface, the surface pressure is lower than that of the central portion of the gut surface. A good impact is hardly transmitted to the player, and a good shot feeling can be obtained.

FIGS. 8 and 9 show a second embodiment of the present invention. This racket 1B has a total length W in the short axis X direction of the gut surface 4 of 240 mm and a total length L in the long axis X direction of 325.
mm. In racquet 1B of the second embodiment, the top portion 2b of the gut surface 4 tip 4c and spacing of the gut J _1,
The distances shown in Table 3 are the distance between the adjacent short-axis guts J ₁ , J ₂ ... J ₁₅ and J ₁₆ and the distance between the gut J ₁₆ and the end 4 d of the gut surface 4 on the yoke portion 2 c side. the horizontal for string holes a _1, a ₂ ... a ₁₅ as, a ₁₆ and _{b 1, b 2 ... b 15} , b
₁₆ are arranged.

[0034]

[Table 3]

In this racket 1B, the gut surface 4
The left end portion 4f and the distance between the gut K _1, gut K ₁ of the adjacent longitudinally, K ₂ ... distance between K _13, K _14, gut K ₁₄
The vertical gut holes c ₁ , c ₂ ... C ₁₅ , c such that the distance between the gut surface 4 and the right end 4 e of the gut surface 4 is the distance shown in Table 4 below.
₁₆ and d ₁ , d ₂ ... D ₁₃ , d ₁₄ are arranged.

[0036]

[Table 4]

Therefore, in the second embodiment, similarly to the first embodiment, the first boundary lines P1, P1, P1 and P2 are located at 2 / 15L on both sides in the long axis Y direction from the center point O of the gut surface 4. The second boundary lines P2 and P2 are set at 2 / 5L on both sides in the major axis Y direction from the center point O, and the region sandwiched between the first boundary lines P1 and P1 is defined as the first region A1 in the major axis direction and the first region A1. Boundary line P1 and second
Assuming that the region sandwiched by the boundary line P2 is the second long-axis direction region A2, the average value l ₁ of the length of the mesh M in the long-axis direction Y in the first long-axis direction region A1 and the second length in the long-axis direction The ratio (l ₁ / l ₂ ) of the length of the mesh M in the major axis Y direction in the region A2 to the average value l ₂ is 0.424.

In the second embodiment, the third boundary lines P3 and P3 are located at 1/5 W from the center point O of the gut surface 4 to both sides in the short axis X direction, and both sides in the short axis X direction from the center point O. To 2/5
A fourth boundary line P4, P4 is set at the position of W, and a region sandwiched between the third boundary lines P3, P3 is a first region in the minor axis direction, a third region.
Assuming that a region sandwiched between the boundary line P3 and the fourth boundary line P4 is a short-axis second region B2, an average value m ₁ of the length of the mesh M in the short-axis X direction in the short-axis first region B1; The ratio (m ₁ / m ₂ ) of the average length m ₂ of the length of the mesh M in the short axis X direction in the second short axis direction region B2 is 0.44.

Further, in the first embodiment, the length l of the mesh M in the major axis direction increases from the central portion 4a toward the peripheral portion 4b.
And the length m in the short axis direction is set to be gradually increased.

By setting the racket 1A of the second embodiment in a gut pattern as described above, the surface pressure of the central portion 4a including the sweet spot is high, while the surface pressure of the peripheral portion 4b is low.

The results of measuring the surface pressure of the racket 1B of the second embodiment with the apparatus shown in FIG. 5A are as shown in FIGS.

As is clear from FIG. 6, the racket 1B of the second embodiment has a surface pressure of about 17.0 kg at the central part 4a of the gut surface 4, whereas the top part 2b and the grip The surface pressure on the part side is about 14.5 kg,
The surface pressure increases as it approaches the central portion 4a of the gut surface 4,
The surface pressure decreases as it approaches the periphery. Therefore, in the racket 1B, even when the ball is hit without the sweet spot, the surface pressure is low and the amount of deformation of the guts J and K is large, so that resilience is good and an unpleasant impact is hardly transmitted to the player, and a good shot feeling can be obtained.

[0043]

[Experimental Examples] Experiments were performed to confirm the effects of the present invention. As a comparative example, a conventional racket 1C shown in FIG.
(Dunlop DP-80 manufactured by Sumitomo Rubber Industries, Ltd.) was prepared.

The racket 1C has guts J ₁ , J ₂ ... J ₁₈ , J ₁₉ in the short-axis X direction and guts K ₁ , K ₂ .
K ₁₅ and K ₁₆ are stretched, and the total length W in the short axis X direction of the gut surface 4 is 240 mm, and the total length L in the long axis X direction is 320 m.
m.

[0045] In this racket 1C, top portion 2b of the front end portion 4a and the spacing of the gut J ₁ GATT surface 4, the distance between adjacent of the short axis direction gut _{J 1, J 2 ... J 18} , J 19 and, is set to a distance shown in Table 5 the distance between the end portion 4b of the yoke portion 2c side of the GATT J ₁₉ and gut surface 4.

[0046]

[Table 5]

In this racket 1C, the gut surface 4
Left end portions 4c and the distance between the gut K ₁ of gut K ₁ of the adjacent longitudinally, K ₂ ... K _15, the distance between K _16, gut K ₁₆
And the distance between the right end 4d of the gut surface 4 is set to the distance shown in Table 6 below.

[0048]

[Table 6]

In this comparative example, the first boundary lines P1, P1 are located on both sides in the major axis Y direction from the center point O of the gut surface 4 at the position of 2 / 15L, and two boundaries are located on both sides in the major axis Y direction from the center point O. /
The second boundary lines P2 and P2 are set at the position of 15L, and the region between the first boundary lines P1 and P1 is defined as the first region A in the long axis direction.
1. Assuming that the region sandwiched between the first boundary line P1 and the second boundary line P2 is the second region A2 in the long axis direction, the first region A1 in the long axis direction
The ratio (l ₁ / l) of the average value l ₁ of the length of the mesh M in the major axis Y direction in the second direction A to the average value l ₂ of the length of the mesh M in the major axis Y direction in the second major axis direction region A2 ₂ ) is 0.63.

The third boundary lines P3 and P3 are located at 1 / 5W from the center point O of the gut surface 4 to both sides in the short axis X direction, and are located at 2 / 5W from the center point O to both sides in the short axis X direction. Are set as the fourth boundary lines P4 and P4, and the region sandwiched between the third boundary lines P3 and P3 is the first region in the short-axis direction, and the third boundary line P3 and the fourth boundary line P4.
Assuming that the region sandwiched by the boundary line P4 is the second short-axis direction region B2, the average value m ₁ of the length of the mesh M in the short-axis direction X in the first short-axis direction region B1 and the second value in the short-axis direction second region B1. the ratio between the average value _{m 2} of the minor axis X direction length of the mesh M in the area B2 _(m 1 / _{m 2)} is 0.74.

FIG. 5 shows the surface pressure of the racket 1C of the comparative example.
The results measured with the device shown in FIG.
As shown in FIG. As shown in FIGS. 11 and 12, in the racket 1C of the comparative example, the central portion 4 of the
a and the peripheral portion 4b have substantially the same surface pressure, and have a uniform surface pressure distribution.

In the present experiment, 17 top-level amateur players used the rackets 1A and 1B of the embodiment (first and second embodiments) and the racket 1C of the comparative example, and Hitting 20 to 30 balls in each of the peripheral portions of the gut surface, and three stages of "normal", "good", and "bad" in resilience, controllability, impact at the time of hitting, shot feeling and spin performance Was evaluated.

The racket 1 of the first and second embodiments
Table 7 shows the weights of the rackets 1A and 1B and the racket 1C of the comparative example, the distance (balance) of the center of gravity from the grip end, and the moment of inertia around the grip end in the swing direction. In addition, gut uses nylon gut,
The warp was stretched with 551b and the weft was stretched with 441b.

[0054]

[Table 7]

The following Tables 8 and 9 show the number of persons who performed each evaluation for each item. First, from Table 8, it can be confirmed that the racket of the example has better controllability and shot feeling when hit at the center of the gut surface than the racket of the comparative example. From Table 9, it can be seen that the racket of the example had better resilience, less impact at the time of hitting, and a better hit feeling when hit at the periphery of the gut surface as compared with the racket of the comparative example. It can be confirmed that there is.

[0056]

[Table 8]

[0057]

[Table 9]

A rebound test was conducted on the racket 1A of the first embodiment, the racket 1B of the second embodiment, and the racket 1C of the comparative example. In this rebound test, as shown in FIG. 13, the tennis ball 20 for the rigid type having the initial velocity V ₀ collides against the gut surface 4 of the rackets 1A and 1B of the first and second embodiments and the racket 1C of the comparative example. The speed Vr of the rebounded tennis ball 20 was measured. In this case, the coefficient of restitution is represented by the following equation (1).

(Rebound coefficient) = Vr / V ₀ (1)

The results of the repulsion test are as shown in FIG. As is clear from FIG. 14, the rackets 1A and 1B of the first and second embodiments of the present invention have almost the same resilience performance as the racket 1C of the comparative example when hit near the center of the gut surface. However, the resilience performance when hitting around the gut surface is the racket 1A of the first and second embodiments,
In 1B, it can be confirmed that the resilience is improved.

[0061]

As is clear from the above description, in the racket according to the present invention, the first boundary line is located on both sides in the longitudinal direction from the center point of the gut surface and at a position of 2/15 of the total length in the longitudinal direction. And the central portion of the racket sandwiched between the first boundary lines is defined as a first region in the long axis direction, and a second boundary line is set at a position ２ of the total length in the long axis direction from the center point. When the region sandwiched between the first boundary line and the second boundary line is the second region in the major axis direction, a mesh formed by the intersection of the major axis gut and the minor axis gut in the major axis first region. The ratio between the average value of the length in the major axis direction and the average value of the length of the mesh in the major axis direction in the second region in the major axis direction is 0.3 to 0.6.
Further, in the racket of the present invention, the third position is set at one-fifth of the total length in the short axis direction on both sides in the short axis direction from the center point of the gut surface.
A boundary line is set, and the central portion of the racket sandwiched between the third boundary lines is defined as a first region in the short axis direction, and a fourth boundary line is located at a position ２ of the total length in the short axis direction from the center point. Set, third
When a region sandwiched between the boundary line and the fourth boundary line is defined as a short-axis direction second region, the average value of the short-axis direction length of the mesh in the short-axis direction first region and the short-axis direction second region Is 0.3 to 0.6 with respect to the average value of the length of the mesh in the minor axis direction. Therefore, in the racket of the present invention, the surface pressure increases as the position approaches the center of the gut surface, while the surface pressure decreases as the position approaches the peripheral portion. Since the surface pressure is low, the amount of deformation of the gut is large and the resilience is good, so that an unpleasant impact is hardly transmitted to the player and a good shot feeling can be obtained. Further, since the racket of the present invention has the surface pressure distribution as described above, the rigidity of the sweet spot portion is sufficient, and good controllability can be obtained when the ball is hit at the center of the gut surface.

[Brief description of the drawings]

FIG. 1 is a partial front view showing a racket of the present invention.

FIG. 2 is a partial front view showing a racket of the present invention.

FIG. 3 is a partial front view showing the racket of the first embodiment.

FIG. 4 is a partial front view showing the racket of the first embodiment.

FIG. 5 (A) is a schematic view showing a surface pressure measuring device,
(B) is a schematic diagram showing an output of the XY recorder.

FIG. 6 is a graph showing a relationship between a distance from a top portion and a surface pressure in the first and second embodiments.

FIG. 7 is a graph showing the relationship between the distance from the right end and the surface pressure in the first and second embodiments.

FIG. 8 is a partial front view showing the racket of the second embodiment.

FIG. 9 is a partial front view showing the racket of the second embodiment.

FIG. 10 is a partial front view showing a racket of a comparative example.

FIG. 11 is a graph showing a relationship between a distance from a top portion and a surface pressure in a comparative example.

FIG. 12 is a graph showing a relationship between a distance from a right end portion and a surface pressure in a comparative example.

FIG. 13 is a schematic view showing a method of a repulsion test.

FIG. 14 is a diagram showing the results of a repulsion test.

[Explanation of symbols]

 1, 1A, 1B, 1C Racket 2 Frame 2a Gut extension A1 Long axis first area A2 Long axis second area B1 Short axis first area B2 Short axis second area J, K Gut M Mesh P Boundary line X short axis Y long axis

Claims (1)

(57) [Claims] 1. A total length (L) in the major axis (Y) direction of two sides on both sides in the major axis (Y) direction from the center point (O) of the gut surface (4).
The first boundary line (P1) is set at the position of / 15, and the central portion (4) of the gut surface (4) sandwiched between the first boundary lines (P1) is set.
a) is the first region (A1) in the long axis direction, and the center point is
A second boundary (P2) is set at a position ２ of the total length (W) in the major axis (X) direction from (O), and is sandwiched between the first boundary (P1) and the second boundary (P2). The region defined as the second region (A2) in the long axis direction is a mesh formed by the intersection of the gut (K) in the long axis direction and the gut (J) in the short axis direction in the first region (A1) in the long axis direction. (M) the average value of the length in the major axis direction (l ₁ );
The ratio (l ₁ / l ₂ ) of the mesh (M) to the average value (l ₂ ) of the length in the long axis direction of the mesh (M) in the second region (A2) in the long axis direction is set to 0.1.
3 to 0.6, and at one-fifth of the total length (W) in the minor axis (X) direction on both sides in the minor axis (X) direction from the center point (O) of the gut surface (4) A third boundary line (P3) is set at the center, and a central portion (4a) of the gut surface (4) sandwiched by the third boundary line (P3) is placed in the short-axis direction first.
In addition to the area (B1), a fourth boundary (P4) is set at a position ２ of the total length (W) in the direction of the short axis (X) from the center point (O), and a third boundary (P3) And a region sandwiched between the fourth boundary line (P4) and the second region (B2) in the minor axis direction, and the length of the mesh (M) in the minor axis (X) direction in the minor region first region (B1). the mean value (m ₁₎ and the ratio of the minor axis (X) direction of the length of the mean value of the mesh (M) in the minor axis direction second region _{(B2) (m 2) (} m 1 / m 2 ) From 0.3 to
A racket characterized by being set to 0.6.