Games using tangible projectile – Golf – Ball
Reexamination Certificate
1999-10-28
2001-04-17
Passaniti, Sebastiano (Department: 3711)
Games using tangible projectile
Golf
Ball
Reexamination Certificate
active
06217463
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-layer solid golf ball comprising at least a core, an inner layer cover, and an outer layer cover. More particularly, it relates to a golf ball in which convex ribs are formed on the inner surface of the outer layer cover such that the convex ribs intrude into the inner layer cover.
2. Related Art
Various techniques have been studied and proposed for increasing travel distance of a golf ball and providing a player with an excellent feel upon hitting the golf ball (hereinafter may be called “hit feel”). Especially in a golf ball having a solid core and a cover, the hardness and size (diameter and thickness) of the core and the hardness and size of the cover are adjusted for such purposes.
For example, U.S. Pat. No. 5,439,227 discloses a three-piece golf ball which has a solid core, an inner layer cover, and an outer layer cover and in which the outer layer cover is made harder than the inner layer cover. Also, U.S. Pat. No. 5,490,674 discloses a three-piece golf ball which has inner and outer solid cores covered with a cover and in which the inner solid core is made harder than the outer solid core.
In the above-described golf balls, the boundary surface of each layer is generally a smooth spherical surface having neither projections nor depressions. However, U.S. Pat. Nos. 2,376,085 and 5,692,973 disclose a golf ball which has on its solid core projections for preventing eccentricity of the solid core, which eccentricity could otherwise arise when a cover is formed around the core through injection molding.
The projections on the solid core of the above-described golf ball are designed to substitute support pins used in an injection molding process, and the effect obtained by the shape of the support-pin-shaped projections is not utilized to improve the performance of the golf ball. In other words, the inventions of U.S. Pat. Nos. 2,376,085 and 5,692,973 relate to a technique for preventing eccentricity of the solid core and preventing mixture of a different material into the cover. According to the technique, by employment of the same material as used for the cover, projections are formed on the core surface such that the cover has a uniform thickness, and the projections and the cover are thus united. As described above, the projections are not designed to improve the performance of the golf ball.
Also, Japanese Patent Application Laid-Open (kokai) No. 9-285565 discloses a two-piece golf ball which has projections and depressions between a solid core and a cover, between two adjacent layers of a multi-layer solid core, or between two adjacent layers of a multi-layer cover. The two-piece golf ball provides a player with different hit feels, depending on the direction of an external force acting on the golf ball during hitting.
The two-piece golf ball has improved in terms of hit feel provided to a player. However, the travel performance and durability are not satisfactory, and there is room for further improvement.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a golf ball in which convex ribs are formed on the inner surface of an outer layer cover such that the convex ribs intrude into an inner layer cover, which has an improved travel performance and controllability, as compared with a conventional golf ball, and which provides a player with an improved hit feel as compared with a conventional golf ball.
In order to achieve the above object, the present inventors have conducted earnest studies, taking notice that when the effect of the configuration at a boundary between the inner layer cover and the outer layer cover of a golf ball; i.e. the cross-sectional, two-dimensional moment of a member that constitutes each of the convex ribs is increased, the bending strength of the member can be increased with no corresponding increase in hardness.
As a result, the present inventors found the following. When convex ribs are formed on the inner surface of the outer layer cover such that the convex ribs intrude into the inner layer cover and that the hardness of the outer layer cover is made greater than that of the inner layer cover, the bending strength of the member—which constitutes the convex ribs—increases because of the effect of the rib shape. As a result, when the golf ball is hit at a relatively high head speed by use of a driver or a like club, the degree of backspin of the golf ball decreases and the travel distance increases accordingly. When the golf ball is hit at a relatively low head speed by use of a short iron or a like club, the hardness of the member does not exceed a level of hardness in conventional golf balls, yielding excellent controllability and providing a soft hit feel.
Moreover, the present inventors conducted further studies and found that when convex ribs are arranged in a network pattern in accordance with a specific manner as described below, while a regular octahedron or icosahedron assumed on the inner surface of the outer layer cover is utilized, travel distance is increased, controllability is improved, and a player is provided with an improved hit feel. In addition, since the convex ribs are arranged uniformly, the effect of the rib shape for increasing strength is maximized efficiently, and the symmetry of a golf ball is secured easily.
The present invention was accomplished on the basis of the above-described findings, and provides the following golf balls (1)-(4).
(1) A golf ball comprising at least a core, an inner layer cover and an outer layer cover, in which convex ribs are formed on the inner surface of the outer layer cover such that the convex ribs intrude into the inner layer cover; the hardness of the outer layer cover is greater than that of the inner layer cover; and the convex ribs are arranged in a network pattern such that when the apexes of each spherical triangle of a hypothetical octahedron or icosahedron assumed on the inner surface of the outer layer cover are each represented by A, the center of the triangle is represented by B, the midpoint of each side of the triangle is represented by C, and a point on a line connecting the center B and each apex A is represented by D, a convex rib is arranged along each of a line between point A and point D, a line between point B and point D, and a line between point C and point D.
(2) A golf ball comprising at least a core, an inner layer cover and an outer layer cover, in which convex ribs are formed on the inner surface of the outer layer cover such that the convex ribs intrude into the inner layer cover; the hardness of the outer layer cover is greater than that of the inner layer cover; and the convex ribs are arranged in a network pattern such that when the apexes of each spherical triangle of a hypothetical octahedron or icosahedron assumed on the inner surface of the outer layer cover are each represented by A, the center of the triangle is represented by B, the midpoint of each side of the triangle is represented by C, and a point on a line connecting the center B and each apex A is represented by D, a convex rib is arranged along each of a line between point A and point D, a line between point B and point C, and a line between point C and point D.
(3) A golf ball comprising at least a core, an inner layer cover and an outer layer cover, in which convex ribs are formed on the inner surface of the outer layer cover such that the convex ribs intrude into the inner layer cover; the hardness of the outer layer cover is greater than that of the inner layer cover; and the convex ribs are arranged in a network pattern such that when the apexes of each spherical triangle of a hypothetical octahedron or icosahedron assumed on the inner surface of the outer layer cover are each represented by A, the center of the triangle is represented by B, points that trisect each side of the triangle are each represented by E, a convex rib is arranged along each of a line between point A and point E, a line between point B and point E, and a line betwe
Maruko Takashi
Masutani Yutaka
Nakamura Atsushi
Yamagishi Hisashi
Bridgestone Sports Co. Ltd.
Gorden Raeann
Passaniti Sebastiano
Sughrue Mion Zinn Macpeak & Seas, PLLC
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