Sumitomo Rubber Industries Limited

Sri Sports Limited

A School Corporation Kansai University

Bycen Co., Ltd.

Keiji Moriyama

Satoshi Iwami

Akira Kato

Kazunari Yoshida

Kazushige Sugimoto

Tadahiro Ebisuno

Masatoshi Yokota

Takeshi Asakura

Keiji Ohama

Kuniyasu Horiuchi

Takashi Sasaki

Yoshinori Sano

Mikio Yamada

Takahiro Sajima

Kazuhiko Isogawa

Seiichiro Endo

Tsutomu Hirau

Hidenori Hiraoka

Masaaki Kikuchi

Kazuya Kamino

Masaya Tsunoda

Masahide Onuki

Kiyoto Maruoka

Hiroaki Tanaka

Kazuo Hochi

Kengo Oka

Masanori Yabu

Hirotaka Nakamura

Kazuhisa Fushihara

Yoshikazu Yabuki

Akihiko Hamada

Hyoungchol Kim

Akihiro Nakahara

Yoshimasa Koizumi

Yoshiyuki Okido

Takumi Nishino

Yasushi Chida

Yoshiyuki Mimoto

Takuzo Iwatsubo

Hiroyuki Tsujinaka

Noritake Araki

Kinuko Tsujinaka, Legal Representative

Minoru Tsujinaka, Legal Representative

Hiroyuki Tsujinaka, Deceased

A cross-sectional shape of each of dimplesof a golf ballis a wave-like curve. The wave-like curve has two first curves, two second curves, two third curves, and one fourth curve. Each first curveand each third curveare upwardly convex. Each second curveand the fourth curveare downwardly convex. Each first curveis connoted to a landat an edge Ed. Each second curveis connected to the first curveat a first inflexion point. Each third curveis connected to the second curveat a second inflexion point. The fourth curveis connected to the third curvesat third inflexion points. In the wave-like curve, the upwardly convex curvesandand the downwardly convex curvesandare alternately arranged.

Golf ball

A swing analysis apparatusfor a golf club includes a club cameracontinuously photographing a behavior of a golf club, a ball cameracontinuously photographing a behavior of a golf ball, and an information processor. The club camerais positioned in front of a golf player. A straight line C passes through a center of a lens of the club cameraand a center of the golf ball. An angle &#x3b8;c between the straight line C and a vertical line Z is 10 degrees or greater and 20 degrees or less. The information processormeasures a synchronized club behavior value from synchronized club image data. The information processormeasures a synchronized ball behavior value from synchronized ball image data. The information processorstores the synchronized club behavior value and the synchronized ball behavior value.

Golf swing analysis apparatus

A plurality of golf clubs having mutually different flex point rates of a shaft is prepared. A subject hits a golf ball with one reference club included in the golf clubs. A face angle of the golf club immediately before hitting is measured by an apparatus. A recommended flex point rate P is calculated by substituting, into the following mathematical expression, the face angle Q and the flex point rate R of the reference club:=0.8648&#xb7;5.033A golf club having a shaft whose difference between the flex point rate and the recommended flex point rate P is within a predetermined range is selected as a recommended club. The subject hits a golf ball with the recommended club. The apparatusmeasures a speed, a launch angle, a backspin speed, a sidespin speed, and a deflection angle of the golf ball.

Method for selecting golf club

Golf ballhas a land and numerous dimpleson the surface thereof. This dimplehas first curved faceand second curved face. The first curved faceis continuous with landat the edge Ed. The second curved faceis continuous with the first curved faceat the boundary point Pb. The first curved facehas ring-shape. The first curved faceis projecting upwards. The second curved facehas a bowl-shape. The second curved faceis projecting downwards. The second curved facehas a curvature radius Rof equal to or greater than 10 mm. The proportion Pof the depth dof the boundary point Pb to the depth de of the dimpleis 1% or greater and 10% or less. The mean diameter of the dimpleis equal to or greater than 4.0 mm. The proportion Pof the number of the dimpleshaving a diameter of equal to or greater than 4.3 mm to total number of the dimplesis equal to or greater than 30%.

A swing analysis method of the present invention includes steps of: preparing a radio type acceleration measuring devicecapable of measuring respective accelerations in three axis directions; mounting the acceleration measuring deviceto a golf player's body t; receiving measured data from the acceleration measuring deviceduring a swing through radio communication; and analyzing a golf swing based on the acceleration data. Preferably, the acceleration measuring device is attached to each of two or more portions of the tester t. Preferably, an attached position of the acceleration measuring device is any part selected from the group consisting of a head, a neck, a shoulder, a back, a waist and a wrist. Preferably, a weight of the acceleration measuring device is equal to or more than 10 g.

Golf swing analysis method using attachable acceleration sensors

According to the present invention, a torque applied from a golf player to a golf club during a swing is analyzed in a time-series manner. A DLT method is suitable as a determination procedure. Preferably, a link model is used in this analysis. Preferably, the three-dimensional coordinate of the mark provided at a position that corresponds to the link model is determined by a DLT method. Preferable analysis method includes: modeling using a golf club, and at least a part of a golf player who grips a grip member of the golf club to provide a link model in which the golf club is connected with the golf player via a joint; and analyzing the torque that acts on the joint is analyzed during the swing in a time-series manner. This joint is positioned in the vicinity of the grip member. This analysis can be applied to a method of diagnosing a swing, a method of selecting a golf club, and a method of designing a golf club.

Analysis method of golf club

The present invention provides a multi-piece solid golf ball, which is superior in flight distance, spin performance and shot feel. The present invention relates to a multi-piece solid golf ball comprising a core consisting of a center and an intermediate layer, and a cover, wherein the center has surface hardness (D) higher than central point hardness by not less than 15, the intermediate layer and cover are formed from thermoplastic resin as a main component and have a thickness of not less than 0.3 to less than 1.0 mm, the cover has a hardness (F) of not less than 35 to less than 55, a hardness of the intermediate layer is higher than D and F, and a difference (A&#x2212;B) between a deformation amount of the core (A) and that of the golf ball (B) is within the range of not less than 0.15 to less than 0.35 mm.

Multi-piece solid golf ball

Three moments of inertia M, M, and M(g&#xb7;cm) about three axes defined in a golf putter are defined in a manner to provide a weight balance satisfying the expressions{(M&#x2212;M)&#x3c;12000} and {M&#x3e;M&#x3e;M

Golf putter and method of designing the same

A golf club comprises a club shaft having a tip end and a butt end, a golf club head being attached to the tip end of the club shaft, and a golf grip being attached to a region of the club shaft extending from the butt end toward the tip end of the club shaft, the golf grip having an upper end by the side of the butt end of said club shaft, wherein the golf club has a club entire length in the range of from 46 to 48 inch, the golf club has a swing weight of from Cto Dbased on 14-inch balance method, and the golf club has a moment of inertia in the range of from 2850 to 3000 kg&#xb7;cmat the position of the upper end of the golf grip.

Golf club

A method of producing a golf ball with uniform thickness by, eliminating defective air between the cover and the core, an insufficient thickness of the cover and an uneven thickness of the cover wherein in the step of heat and compression molding to cover the core or an intermediate layer with shells molded from a cover material mainly composed of a thermoplastic resin, if the mold has a temperature of T&#xb0; C. and the half shells start to flow at a temperature of T&#xb0; C., Tminus Tis set within a range of &#x2212;3&#xb0; C. to +10&#xb0; C.

Method of producing a golf ball

There is provided a method of producing a golf ball, capable of forming a cover to have a uniform thickness to produce a golf ball excellent in resistance to abrasion. The method includes a step to subject a cover material mainly composed of a thermoplastic resin to heat and compression molding to form a half shell, and a step to allow two such half shells to be arranged on a core or an intermediate layer, joined together, and heat and compression molded to mold the cover to have a thickness of 0.3 to 1.5 mm.

A golf ball is provided which contains a core and a cover. In the forming of the cover, two half shells made from a thermoplastic resinous composition are used to cover the core, the composite is put in a spherical mold, then, the mold is clamped. Thereafter, the thermoplastic resin where it is heated and pressurized at a pressure of 5 kgf/cmto 50 kgf/cm, and the excess thermoplastic resin composition flows out of the spherical cavity. Subsequently, the thermoplastic resin composition is heated in the spherical cavity and is pressurized at a pressure of 70 kgf/cmor more whereby the cover is formed. The total volume of the two half shells is 105% to 120% of the volume of the cover.

Golf ball manufacturing method

The invention provides a multi-piece solid golf ball having soft, good shot feel, excellent flight performance, high rebound characteristics and high launch angle, when hit by golfers who swing a golf club at high or low head speed using all golf clubs, namely, a driver to an iron club, a putter. The multi-piece solid golf ball has a core having an inner core and an outer core covering the inner core, and at least one layer covering the core; the inner core has a diameter of 30 to 40.4 mm and surface hardness of 60 to 85 JIS-C, and center JIS-C hardness of the inner core lower than the surface hardness by 5 to 30; the outer core has a thickness of 0.2 to 1.3 mm, and a surface JIS-C hardness of the outer core lower than the surface hardness of the inner core by 2 to 30.

Half shellhas a bowl-like shape, and is composed of a thermoplastic resin composition. The half shellhas a top partand a side part. The thickness Tt of the top partis less than the thickness Ts of the side part. The difference (Ts&#x2212;Tt) between both thicknesses is 0.02 mm or greater and 0.30 mm or less. Two half shellsand a core covered by the half shellsare placed into a mold comprising an upper portion and a lower portion both of which having a semi hemispherical cavity. Upon clamping, the thermoplastic resin composition is compressed while being heated, resulting in outflow of the excess thermoplastic resin composition from the cavity. A cover is formed having the nominal thickness of 0.3 mm or greater and 1.0 mm or less with remained thermoplastic resin composition.

Process for producing golf ball

A golf ball has a large number of dimples (A to D) on a surface thereof. A surface area occupation ratio Y of the dimples is 0.80 to 0.90. A total volume V of the dimples is 300 mmto 700 mm. A mean volume Va to be a value obtained by dividing the total volume V by a total number N of the dimples is 1.30 mmor more. A mean curvature R to be a mean value of a curvature r in the sectional shape of the dimple is 16 mm or more. A mean occupation ratio y to be a value obtained by dividing the surface area occupation ratio Y by the total number N of the dimples is 0.0022 or more. A sum X of a contour length x of the dimple and the surface area occupation ratio Y satisfy a relationship indicated by an expression (I):.&#x2003;&#x2003;(I)

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Kobe, Japan

Keiji Moriyama