BRIEF DESCRIPTION OF THE FIGURES
FIG. 1A is an illustration of face portion of a trial golf club for determining the optimal loft angle in accordance with some embodiments of the present invention.
FIG. 1B is an illustration of a back portion of a trail golf club for determining the optimal loft angle of a golf club in accordance with some embodiments of the present invention.
FIG. 1C is an illustration of a sole portion of a trial golf club for determining the optimal loft angle of a golf club in accordance with some embodiments of the present invention.
FIG. 2 is an illustration of a cross-sectional view taken along the 2-2 line of FIG. 1B of a trial golf club for determining the optimal loft angle of a golf club in accordance with some embodiments of the present invention.
FIG. 3 is an illustration of a golfer using a trial golf club to measure the optimal loft in accordance with some embodiments of the present invention.
FIG. 4 is an illustration of a sole portion of a trial golf club in accordance with some embodiments of the present invention.
FIG. 5 is an illustration of a sole portion of a trial golf club containing an impact mark illustrating an optimal loft angle of a golf club in accordance with some embodiments of the present invention.
FIG. 6 is an illustration of a sole portion of a trial golf club containing an impact mark illustrating a loft angle that is too strong of a golf club in accordance with some embodiments of the present invention.
FIG. 7 is an illustration of a sole portion of a trial golf club containing an impact mark on the sole portion that indicates that the loft angle of a golf club is too weak in accordance with some embodiments of the present invention.
FIG. 8 is a logic flow diagram illustrating a routine for using a trial golf club for determining the optimal loft angle of golf club for a particular golfer in accordance with some embodiments of the present invention.
FIG. 9 is a logic flow diagram illustrating a routine for calculating the optimal loft angle for a golf club in accordance with some embodiments of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Turning now to the figures, in which like numerals refer to like elements through the several figures, FIG. 1A, FIG. 1B, and FIG. 1C, collectively known as FIG. 1, illustrate a trial golf club head 100 for determining the optimal loft of a golf club for use with a custom golf club fitting system. In one embodiment, the trial golf club head 100 is used to determine the loft angle of a hybrid-type or utility-type golf clubs. Normally the hybrid-type golf clubs are meant to replace the long irons, such as the 2-iron, 3-iron, or 4-iron, which are difficult for the average player to hit properly. Characteristically, the hybrid-type golf clubs have loft angles that vary between approximately 16 degrees and 25 degrees and have an incremental change in loft between successive clubs of approximately three degrees. Although the present invention is described as being used to determine the optimal loft angle for hybrid-type golf clubs, those skilled in the art will appreciate that the trial golf club 100 may be used for determining the optimal loft angle of an iron golf club, a wedge type golf club, a fairway metal golf club, or any other type of golf club without departing from the scope of the invention.
FIG. 1A is an illustration of the front view of the trial golf club head 100. The trial golf club head 100 contains a face portion 105 for striking a golf ball, a toe portion 110, a heel portion 115, a sole portion 120, and a leading edge 125 that separates the face portion 105 from the sole portion 120. FIG. 1B illustrates the back view of the trial golf club head 100. The back side contains a back portion 135 and a trailing edge portion 130, which separates the back portion 135 from the sole portion 120.
FIG. 1C illustrates a view of the sole portion 120 of the trial golf club head 100. The sole portion 120 contains a number of graduated indicia 140 that extend between the toe portion 110 and the heel portion 115. The graduated indicia 140 extend substantially between the heel portion 115 and the toe portion 110 and are arranged so that the distance between any two adjacent graduated indicia 140 corresponds to a predetermined incremental loft angle. In an exemplary embodiment, the graduated indicia 140 are a series of equally-spaced solid score lines. Those skilled in the art will appreciate that the graduated indicia 140 may be formed from other indicia, such as dashed score lines, dotted lines, and such, without departing from the scope of the invention.
The distance between adjacent indicia 140 is constant, which means that the corresponding loft angle between successive graduated indicia 140 is also constant. For example, in an exemplary embodiment, the distance between the graduated indicia 140 is between approximately 3 and 5 millimeters and more particularly about 3.75 mm. This corresponds to an incremental loft angle of between approximately 1 degree to approximately 4 degrees, and more particularly 3 degrees, which is the incremental change between loft angles available for hybrid-type golf clubs.
FIG. 2 illustrates a cross-sectional view of the trial golf club head 100 taken along the 2-2 line in FIG. 1B. As shown by the figure, the sole portion 120 of the trial golf club head 100 is cambered, or has a radius of curvature, R, from the face portion 105 to the back portion 135. The radius of curvature of the sole portion 120 is greater than approximately 60 millimeters (mm). In one exemplary embodiment, the radius of curvature of the sole portion 140 from the face portion 105 to the back portion 135 is approximate 71.67 mm. Having a radius of approximately 71.67 mm allows the sole portion 120 to have just enough camber to allow the club to skim along the hitting surface without digging too deeply into the hitting surface, while still allowing the sole portion 120 to record the impact area where the sole portion 120 contacted the ground.
Each of the graduated indicia 140 has a given width, W, in the range of approximately 0.1-1.0 mm. In one exemplary embodiment, the width of the score lines 140 is approximately 0.5 mm. The distance, D, between the center of each graduated indicia 140 is determined by the first calculating the circumference, C, of a circle with a radius of approximately 71.67 mm using the formula:
C=2πR
Substituting the value of 71.67 mm as the value of the radius of curvature, R, yields:
C=2π(71.67 mm)
C=450.50 mm
The distance to travel around an arc, D, three degrees of this circle is equal to three times the circumference, C, of the circle divided by 360 degrees, as given by the formula:
D=3C/360
Substituting the value of the circumference into the equation, yields
D=3(450.50 mm)/360
D=3.75 mm
Therefore the distance between the centers of any two adjacent graduated indicia 140 is 3.75 mm. The gap, G, between two adjacent indicia 140, is determined from the formula:
G=D−(2*(W/2))
where W is the width of each indicia. Substituting the values of the distance, D, and the width of the indicia, W, into the above equation provides:
G=3.75 mm−(2*(0.5 mm/2))
G=3.25 mm.
Although the width between adjacent indicia 140 corresponds to an incremental loft angle of 3 degrees, those skilled in the art will appreciate that the width may be set to correspond to any incremental loft angle, such as 1, degree, 2 degrees, 4 degrees, and the like, without departing from the scope of the invention.
Another feature of the trial golf club head 100 is that the sole has approximately zero degrees of bounce. Bounce is defined as the golf club's potential to repel the ground during contact and prevent the leading edge from digging into the ground. Bounce is measured in degrees of the angle from the front edge 125 to the trailing edge 130 when the golf club rests on the ground at address. A golf club with bounce is characterized by the trailing edge 130 being closer to the ground than the leading edge 125 when the club is addressed behind the ball. Utilizing a bounce of zero degrees ensures that trial golf club head 100 will be resting on the central location of the sole portion 120 when placed on the ground at address. This helps establish the center of the sole portion 120 is resting on the ground and establishes a consistent reference point for determining the optimal loft angle.
FIG. 3 is a diagram of a golfer 300 using a trial golf club 305 with the trial golf club head 100 to determine the optimal loft angle for a golf club, such as a hybrid-type golf club. During a club fitting session, the golfer 300 will typically hit several golf balls off of a lie board 310, or other hard surface using the trial golf club 300. When the trial golf club head 100 makes contact with the lie board 310, an impact mark is left on the sole 120 of the golf club head 100 indicating the point of the sole 120 that makes contact with the ground. The impact mark allows the club fitter to determine whether the loft angle is correct, as explained below. If the golfer 300 swings the trial golf club 300 on the correct swing path 315, the trial golf club head 100 will make contact with the lie board 310 so that the sole portion 120 is parallel to the lie board 310 at the point the trial golf club head 100 makes contact with the ball, as shown in FIG. 4. The lie board 310 will leave an impact mark 505 on the central portion of the sole portion 120, as shown in FIG. 5.
However, if the golfer 300 swings the trial golf club on a steeper swing angle 320, the trial golf club head 100 will be moving at a steeper downward angle relative to the lie board 310, which will de-loft the trial golf club 100. The de-lofting of the trial golf club 300 causes the sole portion 120 to be angled relative to the lie board 310 at the point of impact, such that the leading edge 125 will be closer to the lie board 310 than the trailing edge 130. This orientation of the trial golf club head 100 causes the impact mark 505 to be located between the leading edge 125 and the central portion of the sole 120, as illustrated in FIG. 6. The position of the mark between the leading edge 125 and the central portion of the sole 120 indicates that the golfer 300 has a steep swing angle, which results in a lower ball trajectory and reduced overall distance. By observing at which graduated indicia 140 the impact mark 505 is centered on or nearest to, the number of degrees the club has been de-lofted can be determined. For example, if the distance between each graduated indicia 140 corresponds to an increment of 3 degrees, and the impact mark 505 is centered on the second graduated indicia, then the club has been de-lofted by 6 degrees. The club fitter can then weaken, or add 6 degrees of loft to the golfer's club so that the golf ball achieves the proper trajectory and maximum carry for the particular golfer 300.
Conversely, if the golfer 300 has a shallow or flat swing path 325, the golf club head 100 will be moving at a shallower downward angle relative to the conventional swing path 315. The shallower swing path 325 means that the bottom of the swing path will bottom out behind the ball, which will increase the loft the trial golf club 100. The added loft of the golf club 310 will cause the sole 120 to be angled relative to the lie board 310, such that the leading edge 125 will be farther away from the lie board 310 at the point of impact than the trailing edge 130. This orientation of the trial golf club head 100 causes the impact mark 505 to be located between the central location of the sole portion 120 and the trailing edge 135, as illustrated in FIG. 7. The position of the mark between the central portion of the sole 120 and the trailing edge 135 indicates that the golfer 300 has a shallow swing angle, which results in a higher ball trajectory and reduced distance. By observing at which graduated indicia the impact mark 505 is centered on or nearest to, the number of degrees that have been added to the club 100 by the shallow swing angle can be determined. For example, if the distance between each graduated indicia 140 corresponds to an incremental loft angle of 3 degrees, and the impact mark 505 is centered on the second graduated indicia away from the central portion of the sole 120, then the loft of the trial club must be increased by 6 degrees to allow the golfer to achieve the proper trajectory. The club fitter can then strengthen, or remove 6 degrees of loft to the golfer's custom fit club so that the golfer 300 can achieve the proper loft angle and maximum carry on his or her golf shots.
The sole portion 120 can also contain other types of indicia 145 in combination with the graduated indicia 140. For example, in an exemplary embodiment, the sole portion 120 may contain the letters “H”, “M”, and “L” located near the toe portion 110. The letter “H” is located near the back portion and stands for “high”. It provides the club fitter with a quick reference that if the impact mark 505 appears near the trailing edge 130, the loft is too high for that particular golfer. The letter “M” corresponds to the term “middle” and serves to indicate that if the impact mark 505 appears near the central location of the sole portion, the loft angle is correct for the particular golfer. Similarly, the letter “L” corresponds to “low” and provides a quick indicator that if the impact mark 505 appears near the leading edge 125, the loft angle is too weak for the particular golfer.
FIG. 8 is a logic flow diagram illustrating routine 800 for determining the optimal loft for a golf club using the trial golf club 300. Routine 800 begins at 805, in which a golfer swings the trial golf club 300 at a golf ball located on a hard surface. In an exemplary embodiment, the hard surface may be a lie board 310, which is a thin board, typically ⅛″ thick, made from hard polymer material. The lie board 310 leaves a temporary mark on the sole portion 120 of the trial golf club head 100 at the point where the sole of the club impacted the lie board 310. In some instances, it may be desirable to place a piece of adhesive tape on the sole portion 120 of the golf club head 100. The masking tape will protect the sole portion 120 of the golf club head 100, while still allowing the impact mark from the lie board 310 to be seen. To further enhance the visibility of the mark left by the impact to the sole 120 with the lie board 310, special impact tape may be used in place of the adhesive tape. The impact tape, which is known in the art, changes color to show the point where the sole portion 120 of the golf club head 100 is making contact with the lie board.
At 810, the location of the impact area where the sole portion 120 made contact with the lie board 310 is determined. Typically, the point of impact is determined through visual examination of the sole portion 120 of the golf club head 100. When the sole portion 120 makes contact with the lie board 310, the lie board 310 will impart an impact mark 505 (FIG. 5) on the sole portion 120. The location of the impact mark 505 relative to the central portion of the sole portion 120 is then determined. The graduated indicia 140 that lie closest to the center of the impact mark 505 is determined and the optimal loft for the golf club for the particular golfer 300 is determined.
FIG. 9 is a logic flow diagram illustrating routine 815 of FIG. 8. Routine 815 begins at 905, in which the number of graduated indicia 140 between the graduated indicia closest to the center of the impact mark 505 and the graduated indicia 140 at the central portion of the sole portion 120. At 910, the calculated number of graduated indicia 140 is multiplied by the incremental loft corresponding to the distance between two successive graduated indicia 140 to achieve the total incremental loft that has to be added or subtracted to the loft of the trial golf club. Next, at 915, the determination is made whether the impact mark 505 occurred at the central location of the sole portion 120. If the impact mark occurred at the central location of the sole portion 120, then the loft is correct for the particular golfer 300 and the “YES” branch is followed to the “END” step, as no adjustment to the loft of the golfer's clubs is necessary. However, if the impact mark 505 did not occur at the central location of the sole portion 120, then the “NO” branch is followed to 920.
At 920, the determination is made whether the impact mark 505 occurred between the leading edge 125 and the central portion of the golf club. If the determination is made that the impact mark 505 occurred between the leading edge 125 and the central location of the sole portion 120, then the “YES” branch is followed to the 925, where the calculated incremental loft is added to the initial loft of the trial golf club head 100. Routine 815 then proceeds to the “END” step. However, if the impact mark 505 is not located between the leading edge 125 and the central location of the sole portion 120, the golfer 300 has a shallow swing path and the “NO” branch is followed to 930. At 930 the loft of the trial golf club head 100 is strengthened by subtracting the total calculated incremental loft from the initial loft of the trial golf club head 100. Routine 815 then proceeds to the “END” step.
Other alternative embodiments will become apparent to those skilled in the art to which an exemplary embodiment pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description.
Patent Application
20080085779
