Callaway’s “Secret” Patent Application (Now Patent)

Scoreline designs generally have a cross-section geometry that includes two edges, two side walls and a bottom. The side walls are at a predetermined angle from a vertical line. Usually, each wall has more than one section and those sections are straight or curved. Alternatively, the scoreline design is a “V” shape, in which case there is no bottom other than a vertex or fillet radius.

Iron-type golf clubs having scorelines with sharp edges and relatively vertical side walls are advantageous to golfers since such sharp edged grooves allow golfers to induce higher levels of spin on a ball struck with such an iron-type golf club having sharp edged grooves. Iron-type golf clubs without sharp edged grooves or essentially vertical side walls will induce less spin when impacting a golf ball, especially higher-lofted (40 degrees+) golf clubs.

Backspin is the primary mechanism by which a golfer can control a golf ball upon landing after being struck. Backspin is especially important for short shots where proximity to the hole is of greater consequence to the golfer. High lofted clubs (50 degrees to 75 degrees) have grooves designs which are meant to interact with the surface of a golf ball at impact and remove debris from the contacting surface in order to increase friction and thereby impart more spin on the ball.

Prior irons have scoreline patterns wherein the amount of face area below the bottom scoreline at any position across the face is excessive. This is the result of prior irons having scoreline patterns where the individual scorelines, or grooves, are generally co-linear, or parallel and spaced apart by at least 0.075”. However, since the bottom of an iron face is generally curved, the scorelines are often offset upward from the bottom of the face, perhaps being minimally close to the bottom at one point but substantially further away from the bottom at most points. This leaves a substantial portion of the face near the bottom perimeter with a reduced density of scorelines. Since this portion of the face tends to be hit most often by golfers, the relative scarcity of scorelines in this area can have an adverse effect on the spin imparted to the ball.

The Rules of Golf as interpreted by the United States Golf Association (“USGA”) have constrained the types of scoreline patterns that may be used on golf clubs.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a novel solution to imparting backspin on high lofted golf clubs. The present invention seeks to define a class of scoreline patterns that result in a higher density of scorelines along the bottom perimeter of an iron face. This in turn, results in increased spin on a golf ball when struck low on the face.

The present invention maximizes the number of grooves in contact with a golf ball during an impact. The novel scoreline pattern is based on a higher density of scorelines along the bottom perimeter of an iron-type golf club face.

One aspect of the present invention is an iron-type golf club head having a body and a face. The face has a plurality of scorelines thereon. The plurality of scorelines comprises a plurality of columns of scorelines. Each of the plurality of columns of scorelines offset from an adjacent column of scorelines. Parallel scorelines within a column of scorelines have a parallel spacing greater than 0.075 inch.

Another aspect of the present invention is an iron-type golf club head having a body and a face. The face has a plurality of scorelines thereon. The face having an amount of face area less than 0.12 square inches between the bottom scorelines and the bottom perimeter of the face.