Patent ID: 8029384

Claim:
A golf club head including a striking face having a plurality of grooves formed therein, wherein at least one groove comprises: a first curved side surface; a second curved side surface opposite to said first curved side surface; and a bottom surface connecting said first and second curved side surfaces; wherein said first and second curved side surfaces respectively have first and second involute profiles as viewed in the longitudinal direction of said at least one groove; wherein the first and second involute profiles extend in generally opposite directions, and are respectively defined by the equations below: x = r b cos ⁢ ⁢ α · sin ⁡ ( tan ⁢ ⁢ α - α ) y = r b cos ⁢ ⁢ α · cos ⁡ ( tan ⁢ ⁢ α - α ) wherein the origin of the coordinates is at the center of a predetermined base circle, and r b represents the radius of the predetermined base circle, and α represents the pressure angle between the first involute profile and the predetermined base circle or between the second involute profile and the predermined base circle; wherein a distance measured between said first and said second curved side surfaces continuously increases from said bottom surface to said striking face.