Golf ball with improved directional stability in putting stroke

Abstract

A golf ball having a predetermined radius, and a spherical outer surface with a multiplicity of dimples formed therein, wherein said spherical outer surface has at least one hit portion which has a diameter of 5-15 mm. The hit portion may be an undimpled portion in which the dimples are absent; a single-dimple portion in which the dimples are absent except a single one of the dimples that is located at a central part thereof; a groove portion in which a plurality of grooves are formed; or an increased contact-area portion in which a protrusion is formed in each dimple.

What is claimed is:  
     
         1 . A golf ball having a predetermined radius, and a spherical outer surface with a multiplicity of dimples formed therein, wherein said spherical outer surface has at least one hit portion which has a diameter of 5-15 mm and within which said dimples are absent.  
     
     
         2 . A golf ball according to    claim 1   , wherein said at least one hit portion consists of a plurality of hit portions which are positioned relative to each other such that a center of balance of said plurality of hit portions coincides with the center of the golf ball.  
     
     
         3 . A golf ball according to    claim 1   , wherein said diameter of said at least one hit portion is 8-12 mm.  
     
     
         4 . A golf ball having a predetermined radius, and a spherical outer surface with a multiplicity of dimples formed therein, wherein said spherical outer surface has at least one hit portion which has a diameter of 5-15 mm and within which said dimples are absent except a single one of said dimples that is located at a central part of said hit portion.  
     
     
         5 . A golf ball according to    claim 4   , wherein said at least one hit portion consists of a plurality of hit portions which are positioned relative to each other such that a center of balance of said plurality of hit portions coincides with the center of the golf ball.  
     
     
         6 . A golf ball according to    claim 4   , wherein said diameter of said at least one hit portion is 8-12 mm.  
     
     
         7 . A golf ball having a predetermined radius, and a spherical outer surface with a multiplicity of dimples formed therein, wherein said spherical outer surface has at least one hit portion which has a diameter of 5-15 mm and within which said dimples are absent, and wherein a plurality of grooves are formed within said hit portion and are distributed evenly in the entirety of said hit portion, each of said grooves having a predetermined shape and a width which is smaller, than a diameter of each of said dimples.  
     
     
         8 . A golf ball according to    claim 7   , wherein said at least one hit portion consists of a plurality of hit portions which are positioned relative to each other such that a center of balance of said plurality of hit portions coincides with the center of the golf ball.  
     
     
         9 . A golf ball according to    claim 7   , wherein said diameter of said at least one hit portion is 8-12 mm.  
     
     
         10 . A golf ball according to    claim 7   , wherein said grooves are arranged in a lattice and intersect each other.  
     
     
         11 . A golf ball according to    claim 7   , wherein said grooves are annular grooves having respective diameters different from each other and respective centers lying at a center of said hit portion.  
     
     
         12 . A golf ball according to    claim 7   , wherein said grooves are arranged to be parallel to each other.  
     
     
         13 . A golf ball having a predetermined radius, and a spherical outer surface with a multiplicity of dimples formed therein, wherein said spherical outer surface has at least one hit portion which has a diameter of 5-15 mm and within which a protrusion is formed in each of said dimples, said protrusion having a distal end whose radial distance from the center of the golf ball is equal to said predetermined radius of the golf ball.  
     
     
         14 . A golf ball according to    claim 13   , wherein said at least one hit portion consists of a plurality of hit portions which are positioned relative to each other such that a center of balance of said plurality of hit portions coincides with the center of the golf ball.  
     
     
         15 . A golf ball according to    claim 13   , wherein said diameter of said at least one hit portion is 8-12 mm.  
     
     
         16 . A golf ball according to    claim 13   , wherein said protrusion is positioned relative to said each of said dimples such that said protrusion has a concentric relation with said each of said dimples.  
     
     
         17 . A golf ball according to    claim 13   , wherein said protrusion has a partition wall which divides a space in each of said dimples into a plurality of segmental spaces.