Abstract:
A wood-type golf club head is provided with vertical grooves adjacent at each end of the ball hitting surface in order to enhance the desired gear effect when balls are hit on the toe and heel of the club.

Description:
BACKGROUND OF THE INVENTION 
     It is well known in the golf industry that balls hit from a driver or fairway wood should have a backspin rate adequate to create a stable flight pattern, but not so high as to cause excessive climbing of the ball to the point where roll and distance are sacrificed. An ideal trajectory can be created with a spin rate of approximately 1800 rpm. A spin rate of 3000 rpm, for example, will create a very high trajectory and a serious loss of distance. On the other hand, a very low spin rate, for example under 500 rpm, creates an unstable flight and very short total shot distances. 
     Current methods of creating the desired trajectory include 1) raising or lowering the center of gravity of the club head; 2) creating a low friction face, even to the extent of the elimination of grooves; and 3) reducing the loft of the club face. It has been proven that the first and third techniques work for professional and very low handicap amateurs but not well for the average mid to high handicap golfer. Method 2 gworks for the average player when golfing conditions are perfect but when the ball or club face are wet, thus producing low friction, mis-hits on the toe or heel of the club result in wild and unpredictable shots due to loss of the desired and well known gear effect. Spin rates in the center of the low friction faces are still under control in wet weather even through the spin rate is reduced. 
     BRIEF SUMMARY OF THE INVENTION 
     The problem set forth above can be eliminated by providing vertical grooves on the face of the golf club head. If the entire face of the golf club head is provided with vertical grooves, these grooves will not influence ball spin and flight in the center of the club head but will create the necessary friction and side spin to enhance the desired gear effect when balls are hit on the toe and heel of the club. Alternatively, it is possible to have horizontal grooves in the center of the club face and vertical grooves on both ends of the club face and thus, obtain the same desired result. 
     It is therefore an object of this invention to provide a golf club head having a ball striking surface and providing vertical grooves thereon which will create the necessary friction and side spin to enhance the desired gear effect when balls are hit on the toe and the heel of the club. 
     This, together with other objects of the invention, will become apparent from the following detailed description of the invention and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a golf club head showing the ball striking surface provided with vertical grooves thereon. 
     FIG. 2 is a perspective view of a golf club head showing the ball striking surface with horizontal grooves in the middle thereof and vertical grooves on each side. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is shown a typical wood-type golf club head  10  provided with a hosel  11 , upper and lower surfaces, and a ball striking surface  12 . The ball striking surface  12  is provided with a toe portion and heel portion and is further provided with a plurality of vertical grooves thereon. 
     Referring now to FIG. 2, there is shown a wood-type golf club head  14  provided with a customary hosel  15  and a ball striking surface  16  which is provided with horizontal grooves  17  in the center of the ball striking surface  26  with vertical grooves  18 — 18  being provided on each side thereof. 
     In using golf club heads provided with vertical grooves as shown in FIGS. 1 and 2, notable improvements in the accuracy of ball flight when balls are hit on the heel or toe of the ball striking surface of the golf club head are achieved. 
     EXAMPLE 
     Two identical wood-type drivers were assembled for testing. Driver No.  1  was provided with a normal smooth hitting surface except for horizontal grooves. Driver No.  2  had vertical grooves rather than horizontal grooves. A golf robot using a swing speed of 90 mph was used for the following tests. When the club faces and test balls were dry and balls were hit in the center of the club face, both drivers performed approximately the same. When balls were struck on the toe and the heel, driver No.  1  produced a scatter of 60 feet and driver No.  2  produced a scatter of only 8 feet. When the club faces were lubricated simulating wet conditions on the golf course, both club heads performed similarly on center hits. However, when balls were struck on the heel and toe, driver No.  1  produced a scatter of over 120 feet and driver No.  2  produced a scatter of only 28 feet, thus, demonstrating the effectiveness of vertical grooves on the heel and toe of golf clubs. 
     The center of gravity of the club head of this invention is located to assure the correct trajectory and the face angle is selected to create the desired launch of the ball. The material and surface of the face will be selected to provide the desired coefficient of friction necessary for the desired spin rates. 
     While this invention has been shown and described with respect to a detailed embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the scope of the claims of the invention.