BACKGROUND Golf is a popular sport in which each player, or a golfer, hits a golf ball into a hole with one or successive strokes using various golf clubs in accordance with the rules. Competition is generally played for the lowest number of strokes. Each zone, or a hole, in a golf course includes a teeing ground to start from and an actual hole to put the ball into. Playing a hole is initiated by striking the ball with a club on the teeing ground.
There are three types of golf clubs: putters, irons and woods. A putter is generally used to put the ball into the hole. An iron is generally used to hit the ball at rest on the ground for making relatively short-distance shots. A wood, also called a driver, is generally used for making the first shot at the tee and intended to propel the ball a long distance. Golf clubs are typically made of hardwood, metal or composite material.
Putting a ball into a hole requires precise techniques in the game of golf. Each golfer needs a putter suitably designed and specialized for making short and low-speed strokes so as to smoothly roll the ball into the small cup provided in the green. The putter must be designed to provide technical advantage including smooth stroke, good glide, good impact, and bounce-less topspin ball launch. For this reason, a putter is generally differentiated from the other clubs, i.e., irons and woods, by a club-head with a flat low-profile, low-loft striking face.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates some prior art examples of lower sections of golf putters.
FIG. 2 illustrates a side elevational view of an example of a lower section of a putter according to an embodiment.
FIG. 3 illustrates a magnified cross-sectional side view of the portion of the face indicated by a dotted circle in FIG. 2.
FIGS. 4 and 5 illustrate one flight of wide stairs and one flight of narrow stairs, respectively, formed on the striking face.
FIGS. 6-8 illustrate examples of staircase patterns and corresponding drill hits to be used.
DETAILED DESCRIPTION FIG. 1 schematically illustrates some prior art examples of lower sections of golf putters. A putter generally includes a shaft, a grip attached to the top portion of the shaft, and a head coupled to the bottom portion of the shaft. The head and the shaft may be directly attached to each other, or coupled through a neck that is straight or bent. One surface of the head corresponds to a face for striking a ball. The face orientation is generally configured to be non-parallel to the shaft. That is, a striking face is designed to have a loft angle, or also called a loft, for lifting the ball that was settled into the green. Loft, or loft angle, is defined as an angle in degrees between the striking face and the shaft. It is typically 3°-7°, no more than 10° by the rule. As illustrated in one example in the middle in FIG. 1, some conventional faces are formed to have grooves, which are multiple long narrow channels or depression. The grooves are generally formed horizontally, vertically, a combination thereof, or in other suitable ways. The loft angle and grooves play an important role in putting for getting the ball rolling, smooth and fast.
In view of the dynamics associated with putting activities in golf, this document describes new designs of a striking face of a golf putter. The dynamics of the bail when struck can be fine-tuned by using a putter including, a proper face design, enabling the golfer to attain enhanced control of the rolling direction and distance of the ball. Examples of new designs for a striking face of a golf putter according to embodiments are described below with reference to subsequent drawings. Note that these drawings are not to scale.
FIG. 2 illustrates a side elevational view of an example of a lower section of a putter according to an embodiment. In this example, the putter includes a shaft 104, a head 108 and a neck 112 coupling to the shaft 104 at one end and to the head 108 at the other end. One surface of the head 108 corresponds to a striking face 116. The shaft 104 is positioned vertical to the ground in this example. A loft angle θ is defined as the angle between the shaft 104 and the face 116, as shown in FIG. 2. In general, the initial spinning of the ball when struck by a striking face is primarily determined by the loft angle θ and the pattern formed on the face 116, which is a primary factor for determining the friction, which in turn determines the rotational force to the ball.
FIG. 3 illustrates a magnified cross-sectional side view of the portion of the face 116 indicated by a dashed circle in FIG. 2. As seen in FIG. 3, a pattern of stairs is firmed on the face 116 according to an embodiment. Here, a stair is in the form of a step comprising a tread and a riser, wherein the tread is a horizontal portion and the riser is a vertical portion. Multiple treads and risers are alternatingly connected to form the present pattern, which is in the form of a flight of stairs, each pair of adjacent tread and riser forming an angle of substantially 90°. A slope, or a pitch, of the stairs is the ratio of the total rise to the total run. The lengths of the multiple treads may be made substantially the same; and the lengths of the multiple risers may be made substantially the same. A slope line, or a pitch line, can he defined as the imaginary line along the tip of the nosing of the steps. The pattern of stairs according to the present embodiment is formed so that the angle between the slope line of the stairs and the shaft 104 corresponds to the loft angle θ, as shown in FIG. 2. Mathematically, assuming that all the treads have the same length, all the risers have the same length, and each pair of adjacent tread and riser form an angle of 90°, the relationship among these parameters can be expressed as follows:
tan (9°-θ)=slope=total rise/total run=length of a riser/length of a tread. Eq. (1)
The advent of computer numerical control (CNC) milling machines in recent years allows for machining parts to precise sizes and shapes with very fine dimensions. An example milling machine can remove material from a workpiece to form a fine line with a width of 1 mm, or even narrower. Furthermore, by use of modern-day laser engraving machines. e.g., CO2 laser engravers, even narrower lines can be formed. Owing to these high-tech fabrication machines, dimensions of lines or grooves that can be formed on a metal surface are controllable over a wide range. For example, to achieve the loft angle θ=4, with the riser having, a length of 0.9 mm, the length of a tread is about 0.06 mm, which is well within the capability of a modern-day CNC milling machine. Again, using a laser engraving machine, even finer dimensions can he achieved. Thus, the lengths of the riser and the tread of the stair shape can be varied to provide the optimum friction to the ball, depending on the weight and surface pattern of the ball, the weight and shape of the putter, typical swing angles, weather, and various other factors and conditions. However, it may be considered that the finer the dimensions of the staircase pattern, the smoother the traction is.
FIGS. 4 and 5 illustrate one flight of wide stairs and one flight of narrow stairs, respectively, formed on the striking face. Again, it should be emphasized that these drawings are not to scale. Each figure illustrates a front elevational view looking towards the striking face 116. The pattern of stairs is formed so that the width extends horizontally on the putter face. The striking face of the example in FIG. 4 has a pattern of one flight of wide stairs, which are configured to be wide so as to cover most of the surface, e.g. ˜90%. The striking face of the example in FIG. 5 has a pattern of one flight of narrow stairs, which are configured to he narrow so as to cover substantially the center portion of the surface, e.g., 40-˜60% in width. In general, the diameter of a golf ball is substantially smaller than the width of a putter face. As such, if the golfer is skilled to hit the ball using substantially the center portion of the face, the pattern of the narrow flight of stairs, as illustrated in FIG. 5, may be sufficient to provide the optimum friction from the pattern to the bail for spinning. Another example may include a pattern of two or more flights of stairs, the flights formed vertically and adjacent to each other with a gap in between. These and other variations are possible for providing various frictional forces depending on preferences of golfers, weather conditions, types of balls, materials of the putter heads, etc. Thus, the striking face of a putter can be formed with a pattern including one or more flights of stairs that have respective widths, as exemplified in FIGS. 4 and 5, configured to provide a frictional force for generating proper spinning of the ball when struck. As a result, smooth and fast rolling of the ball can be attained by using a putter including the present face design, enabling: the golfer to have a precise control of the rolling direction and distance.
The striking faces in the above examples include a pattern of stairs, wherein the slope line of the stairs corresponds to the line determining the loft angle of the putter, as illustrated in FIGS. 2 and 3. However, a wide variety of drill bits can be used to form a wide variety of staircase patterns on the striking face. FIGS. 6-8 illustrate examples of staircase patterns and corresponding drill bits to be used. FIG. 6 illustrates that a typical end mil bit having a 90-degree edge can be used to form a pattern of stairs, wherein each step is defined by a tread (a) and a riser (h) having a relative angle of substantially 90°. The loft angle (θ) is determined as in Eq. (1). FIG. 7 illustrates that a so-called dove tail bit can be used to form a pattern of stairs, wherein each step is defined by a tread (a) and a riser (b) having a relative angle of less than 90°, i.e., an acute angle. The loft angle (θ) is determined as in Eq. (1), except that: total rise/total run≠b/a, in this case. FIG. 8 illustrates that a tapered end mill bit can be used to form a pattern of stairs, wherein each step is defined by a tread (a) and a riser (b) having a relative angle of more than 90°, i.e., an obtuse angle. The loft angle (θ) is determined as in Eq. (1), except that: total rise/total run≠b/a, in this case. As mentioned earlier, based on modern-da milling technologies with high-precision drill bits, these staircase patterns and their variations can be formed with fine dimensions with a<0.1 mm and b<1 mm, e.g., a=0.06 mm and b=0.9 mm, to achieve a loft angle in the range of 3°-7° for a striking face of a putter.
While this document contains many specifics, these should not be construed as limitations on the scope of an invention or of what may be claimed, but rather as descriptions of features specific to particular embodiments of the invention. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be exercised from the combination, and the claimed combination may be directed to a subcombination or a variation of a subcombination.
