US Patent 7442132 Golf club head

A golf club head includes a face including a bulge formed at the center of a backside thereof and having a thickness of 2.0 or more times the thickness of the thinnest part, and a plurality of ribs extended from the bulge toward a circumference of the face. Six or more ribs are provided as the plural ribs and an angle θ(°) formed between extension directions of a respective pair of adjoining ribs is less than 90°. The maximum thickness of the bulge is not more than 3.5 times the thickness of the thinnest part.