Patent ID: 6719642
Filing Date: 2004-04-13
Classification: A63B

Abstract:
A golf club head comprising:a body including an upper portion having a top edge and a rearwardly extending lower portion having a bottom edge, wherein said upper and lower portions together form a substantially planar striking face having a loft angle between about 17Â° and 50Â°, as measured from a vertical axis, said striking face having a length, and wherein a rear side of said lower portion has at least a first recess adjacent a toe end and at least a second recess adjacent a heel end; wherein a lateral axis is defined at the junction between said upper and lower portions of said body, extending from said toe end to said heel end, with a reference point being defined at a mid portion of said lateral axis, between about 55% and about 75% of the height of the striking face, as measured from said bottom edge to said top edge, and wherein a central axis is defined substantially parallel to said lateral axis, at about 50% of the face height; wherein said first recess comprises a first volume and said second recess comprises a second volume, said first and second recesses extending downwardly at least to said central axis, and wherein the portions of the body that define said first and second recesses each have a stiffness no more than 90% greater than a minimum stiffness of said upper portion, while the remainder of said lower portion has a stiffness at least 230% greater than the stiffness at each of the first and second recesses; wherein a central region of said lower portion, located below said reference point, has a maximum stiffness that is at least about 30 times a maximum stiffness of said upper portion, wherein regions below said first and second recesses each have a maximum stiffness at least about 20 times the maximum stiffness of said upper portion, wherein a stiffness zone is located within said central region, at said central axis and extending halfway toward said lateral axis and, between said first and second recesses, at least about 20% of the length of said striking face, such that a relative stiffness is established between said central region and said upper portion and between said central region and said first and second recesses.