Racket

This application claims priority to and the benefit of Japanese Patent Application No. 2024-075191, filed on May 7, 2024, the entire disclosure of which is incorporated herein by reference.

The present specification discloses a racket for use in, for example, tennis.

A tennis racket includes a frame, a main string, and a cross string. A tennis racket is required to have good spin performance, control performance, feel at impact, etc. Japanese Laid-Open Patent Application Publication No. 2021-133084 discloses a tennis racket including a first main string and a second main string. The second main string has specifications different from the specifications of the first main string.

In recent tennis competitions, players often make swings in a manner to impart high-speed spin to a ball. Spin performance of a tennis racket is important. Spin performance of a racket is important also in other racket sports different from tennis. It is an intention of the applicant of the present application to provide a racket having excellent spin performance.

The present specification discloses a racket including: a head including a top and a bottom; and a face whose contour is formed by the head. The face includes a plain weave structure including a plurality of longitudinal threads, a plurality of high-tension transverse threads, and a plurality of low-tension transverse threads. The plain weave structure includes one or more spin facilitating zones. Each spin facilitating zone includes: (1) a first high-tension transverse thread; (2) a second high-tension transverse thread; and (3) an odd number of low-tension transverse threads positioned between the first high-tension transverse thread and the second high-tension transverse thread. The spin facilitating zone includes no other high-tension transverse thread positioned between the first high-tension transverse thread and the second high-tension transverse thread.

Hereinafter, preferred embodiments are described in detail with reference to the drawings as necessary.

each show a tennis racket. The tennis racketincludes a frame, a grip, an end cap, a grommet, and a face. The tennis racketcan be used in regulation-ball tennis. In, an arrow X represents the width direction of the tennis racket; an arrow Y represents the axial direction of the tennis racket; and an arrow Z represents the thickness direction of the tennis racket. In, reference character CL indicates a center line of the tennis racket, the center line passing through the center of the tennis racketin the width direction X.

The frameincludes a head, two throats, and a shaft. The headforms the contour of the face. In the present embodiment, the front view shape of the headis substantially an ellipse. The major axis direction of the ellipse coincides with the axial direction Y of the tennis racket. The minor axis direction of the ellipse coincides with the width direction X of the tennis racket. The headincludes a topand a bottom. In, reference sign Pc indicates the center point of the head. The distance from the center point Pc to the bottomis equal to the distance from the center point Pc to the top.

One end of each throatis continuous with the head. Each throat, at the vicinity of the other end thereof, merges with the other throat. The throatsextend from the headto the shaft. The shaftextends from the location where the two throatsmerge together. The shaftis formed so as to be continuous with, and integrated with, the throats. A portion of the head, the portion being positioned between the two throats, is a yoke.

The frameis hollow. The material of the frameis 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.

As shown in, the headincludes a grommet groove. The grommet grooveis recessed from the outer peripheral surface of the head. As shown in, the grommet grooveis formed over substantially the entire periphery of the head, except the yoke.

As shown in, the headincludes a plurality of holes. Each holeextends through the head. The plurality of holesare arranged over substantially the entire periphery of the head.

The gripis formed by a tape wound around the shaft. The gripsuppresses slip between a hand of a player and the tennis racketwhen the tennis racketis swung by the player. The end capis attached to the end of the grip.

As shown in, the grommetincludes a baseand a plurality of pipes. The baseis belt-shaped. Each pipeis formed so as to be integrated with the base. Each piperises from the base.

The material of the grommetis typically a synthetic resin that is softer than the frame. The racketmay include a plurality of grommets. Each grommetmay be spaced apart from its adjacent grommet(s). The number of pipesof each grommetmay be one.

The grommetis attached to the head. In a state where the grommetis attached to the head, the baseis accommodated in the grommet groove. The basemay partly protrude from the grommet groove. In the state where the grommetis attached to the head, the pipesextend through the respective holes. Each pipeis passed through a corresponding one of the holes.

shows part of the face. The faceincludes a plurality of longitudinal threads, a plurality of high-tension transverse threads, and a plurality of low-tension transverse threads. A tension Tof the low-tension transverse threadsis less than a tension Tof the high-tension transverse threads. Each longitudinal threadis stretched on the headin the axial direction Y. Each longitudinal threadcrosses the plurality of transverse threads (i.e., the transverse threadsand the transverse threads). Each high-tension transverse threadis stretched on the headin the width direction X. Each high-tension transverse threadcrosses the plurality of longitudinal threads. Each low-tension transverse threadis stretched on the headin the width direction X. Each low-tension transverse threadcrosses the plurality of longitudinal threads. The facegenerally extends along an X-Y plane.

The tennis racketincludes a main string. The main stringis shown in. The main stringis stretched on the headin a zigzag manner. The main stringis passed through the plurality of holes(see). In other words, the main stringis passed through the plurality of pipes. The plurality of longitudinal threadsare formed by the main string. In the present embodiment, sixteen longitudinal threadsare formed by one main string. These longitudinal threadsare arranged symmetrically with respect to the center of the headin the width direction. The tennis racketmay include a plurality of main strings.

The tennis racketincludes a high-tension cross string. The high-tension cross stringis shown in. The high-tension cross stringis stretched on the headin a zigzag manner. The high-tension cross stringis passed through the plurality of holes(see). In other words, the cross string is passed through the plurality of pipes. The plurality of high-tension transverse threadsare formed by the high-tension cross string. In the present embodiment, ten high-tension transverse threadsare formed by one high-tension cross string. The tennis racketmay include a plurality of high-tension cross strings. The high-tension cross stringmay be integrated with the main string(see).

The tennis racketincludes a low-tension cross string. The low-tension cross stringis shown in. In, the low-tension cross stringis illustrated as a dotted line to distinguish it from the high-tension cross string. The low-tension cross stringis stretched on the headin a zigzag manner. The low-tension cross stringis passed through the plurality of holes(see). In other words, the cross string is passed through the plurality of pipes. The plurality of low-tension transverse threadsare formed by the low-tension cross string. In the present embodiment, nine low-tension transverse threadsare formed by one low-tension cross string. The tennis racketmay include a plurality of low-tension cross strings.

shows the high-tension cross stringand the low-tension cross string. As previously described, in the present embodiment, ten high-tension transverse threadsare formed by the high-tension cross string, and nine low-tension transverse threadsare formed by the low-tension cross string. Therefore, the number of transverse threads is nineteen. The holesthrough which the high-tension cross stringis passed are selected, and also, the holesthrough which the low-tension cross stringis passed are selected. Accordingly, in the face, the low-tension transverse threadsdo not overlap the high-tension transverse threads. In the present embodiment, the high-tension transverse threadsand the low-tension transverse threadsare arranged alternately from the toptoward the bottom.

In, reference signseach indicate a spin facilitating zone. In the present embodiment, the number of spin facilitating zonesis nine. Each spin facilitating zoneincludes two high-tension transverse threadsand one low-tension transverse threadpositioned between these two high-tension transverse threads. The high-tension transverse threadpositioned between two spin facilitating zonesthat are adjacent to each other belongs to one of these spin facilitating zones, and belongs also to the other spin facilitating zone.

shows the headand the face. The faceis formed by the plurality of longitudinal threads, the plurality of high-tension transverse threads, and the plurality of low-tension transverse threads. The faceincludes a plain weave structure. With reference toin addition to, it is clear that in the plain weave structure, each longitudinal threadcrosses the plurality of transverse threads in a manner to pass their front side and reverse side alternately. When the longitudinal threadpasses the front side of one of two transverse threads that are adjacent to each other, the longitudinal threadpasses the reverse side of the other one of the two transverse threads. On the other hand, when the longitudinal threadpasses the reverse side of one of two transverse threads that are adjacent to each other, the longitudinal threadpasses the front side of the other one of the two transverse threads. In the plain weave structure, each transverse thread crosses the plurality of longitudinal threadsin a manner to pass their front side and reverse side alternately. When the transverse thread passes the front side of one of two longitudinal threadsthat are adjacent to each other, the transverse thread passes the reverse side of the other one of the two longitudinal threads. On the other hand, when the transverse thread passes the reverse side of one of two longitudinal threadsthat are adjacent to each other, the transverse thread passes the front side of the other one of the two longitudinal threads. The tennis racketincluding the plain weave structure can conform to the rules of the International Tennis Federation.

shows part of a cross section taken along line X-X in.shows one high-tension transverse threadand five longitudinal threads.shows the cross section of each longitudinal thread. Since the facehas the plain weave structure, the high-tension transverse threadcrosses the plurality of longitudinal threadsin a manner to pass their front side and reverse side alternately. The longitudinal threadsrestrain the high-tension transverse thread. The high-tension transverse threadrestrains the longitudinal threads.

shows part of a cross section taken along line XI-XI in.shows one low-tension transverse threadand five longitudinal threads.shows the cross section of each longitudinal thread. Since the facehas the plain weave structure, the low-tension transverse threadcrosses the plurality of longitudinal threadsin a manner to pass their front side and reverse side alternately. The longitudinal threadsrestrain the low-tension transverse thread. The low-tension transverse threadrestrains the longitudinal threads.

It is clear from comparison withthat the low-tension transverse threadinis bent to a greater degree than the high-tension transverse threadin. This bending occurs as a result of receiving force from the longitudinal threads. Due to the tension Tof the low-tension transverse threadbeing less than the tension Tof the high-tension transverse thread, the low-tension transverse threadis bent to a greater degree than the high-tension transverse thread. The restraining force of the low-tension transverse threadto restrain the longitudinal threadsis less than the restraining force of the high-tension transverse threadto restrain the longitudinal threads.

shows part of a cross section taken along line XII-XII in.shows a first longitudinal thread, four high-tension transverse threads, and three low-tension transverse threads.shows the cross section of each transverse thread. Since the facehas the plain weave structure, the first longitudinal threadcrosses the transverse threads in a manner to pass their front side and reverse side alternately. In a case where it is assumed that the right side inis the front side of the face(hereinafter, “the face side”), the left side inis the reverse side of the face(hereinafter, “the back side”).

shows a spin facilitating zone(see also). The spin facilitating zoneincludes a first high-tension transverse threadand a second high-tension transverse thread. The spin facilitating zonefurther includes a first low-tension transverse thread. The first low-tension transverse threadis positioned between the first high-tension transverse threadand the second high-tension transverse thread. Between the first high-tension transverse threadand the second high-tension transverse thread, no other high-tension transverse threadis present.

The first high-tension transverse threadis positioned on the face side with respect to the first longitudinal thread. The second high-tension transverse threadis also positioned on the face side with respect to the first longitudinal thread. The first low-tension transverse threadis positioned on the back side with respect to the first longitudinal thread. In the spin facilitating zone, the first longitudinal threadis exposed to the face side. Since the restraining force of the first low-tension transverse threadto restrain the first longitudinal threadis small, the degree of bending of the first longitudinal threadin the spin facilitating zoneis small.

When hitting a drive shot, a tennis player swings the racketsuch that the facemoves mainly in the width direction X. When the first longitudinal threadcollides with a tennis ball, force in the width direction X is exerted on the first longitudinal thread. As mentioned above, the restraining force of the first low-tension transverse threadto restrain the first longitudinal threadis small. Accordingly, when the tennis ballcollides with the face side of the face, the first longitudinal threadin the spin facilitating zonereceives the force from the tennis ball, and consequently, the first longitudinal threadis sufficiently deformed in the width direction X. The first longitudinal threadis restored after the deformation. The restoration imparts overspin to the tennis ball. This tennis rackethas excellent spin performance.

The degree of bending of the first high-tension transverse threadand the degree of bending of the second high-tension transverse threadare small (see). Therefore, these high-tension transverse threadsare less likely to hinder the deformation of the first longitudinal thread

shows part of a cross section taken along line XIII-XIII in. Similar to,shows the spin facilitating zone. The spin facilitating zoneincludes a first high-tension transverse threadand a second high-tension transverse thread. The spin facilitating zonefurther includes a first low-tension transverse thread. The first low-tension transverse threadis positioned between the first high-tension transverse threadand the second high-tension transverse thread. Between the first high-tension transverse threadand the second high-tension transverse thread, no other high-tension transverse threadis present.further shows a second longitudinal thread. The second longitudinal threadis positioned adjacently to the first longitudinal threadshown in(see also).

The first high-tension transverse threadis positioned on the back side with respect to the second longitudinal thread. The second high-tension transverse threadis also positioned on the back side with respect to the second longitudinal thread. The first low-tension transverse threadis positioned on the face side with respect to the second longitudinal thread. In the spin facilitating zone, the second longitudinal threadis exposed to the back side. Since the restraining force of the first low-tension transverse threadto restrain the second longitudinal threadis small, the degree of bending of the second longitudinal threadin the spin facilitating zoneis small.

As mentioned above, the restraining force of the first low-tension transverse threadto restrain the second longitudinal threadis small. Accordingly, when the tennis ballcollides with the back side of the face, the second longitudinal threadin the spin facilitating zonereceives the force from the tennis ball, and consequently, the second longitudinal threadis sufficiently deformed in the width direction X. The second longitudinal threadis restored after the deformation. The restoration imparts overspin to the tennis ball. This tennis rackethas excellent spin performance.

The degree of bending of the first high-tension transverse threadand the degree of bending of the second high-tension transverse threadare small (see). Therefore, these high-tension transverse threadsare less likely to hinder the deformation of the second longitudinal thread

In the spin facilitating zone, the plurality of longitudinal threadsexposed to the face side and the plurality of longitudinal threadsexposed to the back side are arranged alternately in the width direction X. The spin facilitating zonefacilitates spin in a case where the tennis ballcollides with the face side of the face, and also facilitates spin in a case where the tennis ballcollides with the back side of the face.

Each of the spin facilitating zonesshown infacilitates spin in a case where the tennis ballcollides with the face side of the face, and also facilitates spin in a case where the tennis ballcollides with the back side of the face.

The high-tension transverse threadswhose tension Tis high can contribute to the control performance of the tennis racket. The low-tension transverse threadswhose tension Tis low can contribute to high launch speed of the tennis ball. Further, the low-tension transverse threadscan contribute also to a soft feel at impact of the tennis racket.

In light of spin performance, control performance, launch speed, and feel at impact, a tension difference (T−T) is preferably greater than or equal to 10 pounds, more preferably greater than or equal to 15 pounds, and particularly preferably greater than or equal to 20 pounds. In light of the durability of the face, the difference (T−T) is preferably less than or equal to 50 pounds, more preferably less than or equal to 40 pounds, and particularly preferably less than or equal to 35 pounds.

In light of spin performance, control performance, launch speed, and feel at impact, a tension ratio (T/T) is preferably greater than or equal to 1.2, more preferably greater than or equal to 1.3, and particularly preferably greater than or equal to 1.4. In light of the durability of the face, the ratio (T/T) is preferably less than or equal to 3.0, more preferably less than or equal to 2.7, and particularly preferably less than or equal to 2.5.

In light of control performance, the tension Tof the high-tension transverse threadsis preferably greater than or equal to 40 pounds, more preferably greater than or equal to 45 pounds, and particularly preferably greater than or equal to 50 pounds. In light of launch speed and feel at impact, the tension Tof the low-tension transverse threadsis preferably less than or equal to 50 pounds, more preferably less than or equal to 45 pounds, and particularly preferably less than or equal to 40 pounds.

When stretching the high-tension cross stringon the head, the tension Tof the high-tension transverse threadscan be adjusted. When stretching the low-tension cross stringon the head, the tension Tof the low-tension transverse threadscan be adjusted. The high-tension cross stringis not integrated with the low-tension cross string. Therefore, a decrease in the tension Tof the high-tension transverse threadswill not cause an increase in the tension Tof the low-tension transverse threads. Further, an increase in the tension Tof the low-tension transverse threadswill not cause a decrease in the tension Tof the high-tension transverse threads.

A tension Tof the longitudinal threadsmay be greater than the tension Tof the high-tension transverse threads. The tension Tof the longitudinal threadsmay be equal to the tension Tof the high-tension transverse threads. The tension Tof the longitudinal threadsmay be less than the tension Tof the high-tension transverse threadsand greater than the tension Tof the low-tension transverse threads. The tension Tof the longitudinal threadsmay be equal to the tension Tof the low-tension transverse threads. The tension Tof the longitudinal threadsmay be less than the tension Tof the low-tension transverse threads.

In a case where the tension Tof the longitudinal threadsis equal to the tension Tof the high-tension transverse threads, the plurality of longitudinal threadsand the plurality of high-tension transverse threadsmay be formed by one string. In a case where the tension Tof the longitudinal threadsis equal to the tension Tof the low-tension transverse threads, the plurality of longitudinal threadsand the plurality of low-tension transverse threadsmay be formed by one string.

Preferably, the tension Tof the longitudinal threadsis greater than the tension Tof the low-tension transverse threads. In light of spin performance, control performance, launch speed, and feel at impact, a tension difference (T−T) is preferably greater than or equal to 5 pounds, more preferably greater than or equal to 10 pounds, and particularly preferably greater than or equal to 15 pounds. In light of the durability of the face, the difference (T−T) is preferably less than or equal to 45 pounds, more preferably less than or equal to 35 pounds, and particularly preferably less than or equal to 30 pounds.

In light of spin performance, control performance, launch speed, and feel at impact, a tension ratio (T/T) is preferably greater than or equal to 1.1, more preferably greater than or equal to 1.2, and particularly preferably greater than or equal to 1.3. In light of the durability of the face, the ratio (T/T) is preferably less than or equal to 3.0, more preferably less than or equal to 2.7, and particularly preferably less than or equal to 2.5.

In the present embodiment, in each spin facilitating zone, the number of low-tension transverse threadspositioned between the first high-tension transverse threadand the second high-tension transverse threadis one. Alternatively, the number of low-tension transverse threadspositioned between the first high-tension transverse threadand the second high-tension transverse threadin each spin facilitating zonemay be an odd number different from one. Specifically, it may be three or five. Ideally, it is one.

Preferably, the material of each string is a synthetic resin or a natural material. Preferable examples of the synthetic resin include nylon and polyester. The natural material is preferably natural gut. The material of the high-tension cross stringmay be the same as or different from the material of the main string. The material of the low-tension cross stringmay be the same as or different from the material of the main string. The material of the low-tension cross stringmay be the same as or different from the material of the high-tension cross string.

shows part of a tennis racketaccording to another embodiment.shows a head, a plurality of high-tension transverse threads, and a plurality of low-tension transverse threads. Each high-tension transverse threadis illustrated as a solid line, and each low-tension transverse threadis illustrated as a dotted line. Similar to the tennis racketshown in, the tennis racketincludes a plurality of longitudinal threads. The illustration of the longitudinal threads is omitted in. Similar to the tennis racketshown in, the tennis racketincludes a grip, an end cap, a grommet, throats, a shaft, etc.

The tennis racketincludes three spin facilitating zones. Each spin facilitating zoneincludes two high-tension transverse threadsand one low-tension transverse threadpositioned between these two high-tension transverse threads. Each spin facilitating zoneis positioned on the top side with respect to the center point Pc. Similar to the spin facilitating zonesshown in, each spin facilitating zonefacilitates spin in a case where the tennis ballcollides with the face side of the face, and also facilitates spin in a case where the tennis ballcollides with the back side of the face.