Patent Publication Number: US-9427632-B2

Title: Golf club heads with enlarged grooves

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 13/085,396, filed Apr. 12, 2011, the contents of which are incorporated herein by reference in their entirety. 
     FIELD OF THE INVENTION 
     The invention relates to golf club heads with grooves. 
     BACKGROUND OF THE INVENTION 
     Golf club heads come in many different forms and makes, such as wood-type or metal-type, iron-type (including wedge-type club heads), utility or specialty-type, and putter-type. Each of these types has a prescribed function and make-up. The invention will be discussed as relating to iron-type clubs, in particular, wedge-type club heads, but the inventive teachings disclosed herein may be applied to other types of clubs. 
     Iron-type golf club heads generally include a front or striking face, a back, a toe, a heel, a top line, a hosel, and a sole. The front face interfaces with and strikes the golf ball. A plurality of grooves, sometimes referred to as score lines, is provided on the face to assist in imparting backspin to the ball. The portion of the front face where impact with the golf ball is intended is referred to as the impact area. The back can also be described as the back of the striking face and may vary in design, depending whether the iron-type golf club head is a blade, muscle back or cavity back design. The hosel is generally configured to have a particular look to the golfer, to provide a lodging for the golf shaft, and to provide structural rigidity for the club head. The sole of the golf club is particularly important to the golf shot because it contacts and interacts with the playing surface during the swing. The toe is the region of the golf club head that is distal to the shaft, while the heel is the region of the golf club head that is proximal to the shaft. The top line is the uppermost region of the golf club head, extending between the toe and heel of the golf club head. 
     In conventional sets of iron-type golf clubs, each club includes a shaft with a club head attached to one end of the shaft, and a grip attached to the other end of the shaft. The angle between the striking face and a vertical plane is called the loft angle. Usually, the shaft is oriented vertically when the golfer holds the golf club in the proper address position. 
     The United States Golf Association (USGA) publishes and maintains the Rules of Golf, which govern golf in the United States. Appendix II to the USGA Rules provides limitations for golf clubs. Several of these rules are particularly relevant to the design of the grooves and the striking face. For example, the following USGA rules regulate the geometry of the grooves: grooves must be straight and parallel; grooves must have a plain symmetrical cross-section and sides which do not converge; the width, spacing and cross section of the grooves must be consistent throughout the impact area; the width of a groove cannot exceed 0.035 inch; the distance between edges of adjacent grooves cannot be less than three times the width of the grooves and not less than 0.075 inch; the depth of each groove cannot exceed 0.020 inch; the cross-sectional area of a groove divided by the groove pitch must not exceed 0.0030 in 2 /in; grooves must not have sharp edges or raised lips; and groove edges must be substantially in the form of a round having an effective radius which is not less than 0.010 inch and not greater than 0.20 inch. Further, the surface roughness of the impact area cannot exceed that of decorative sandblasting or fine milling. The Royal and Ancient Golf Club of St Andrews (R&amp;A), which is the governing authority for the rules of golf outside the United States, provides similar limitations to golf club design. 
     In 2008, the USGA announced the abovementioned new restrictions on groove design. Previous to 2008, the groove design rules were more lenient, which generally resulted in golf clubs, particularly wedges, with greater ball back-spinning capability. Under the pre-2008 rules, manufacturers generally used the same U-shaped groove design, with maximum allowable width, depth, volume, and number of grooves. Further, manufacturers generally utilized sharp radii on the edge of the grooves. The similar groove designs across the manufacturers were a direct result of consumer demand—golf club designers found that the maximum-sized grooves produced the greatest ball backspin. 
     However, as a result of the changes to the groove design rules, manufacturers are asked to stop manufacturing golf clubs that do not comply with the new groove design rules starting in 2011, but can sell inventory of these pre-2008 rules golf clubs through 2011. For golf professionals, they are required to compete using golf clubs compliant with the new groove rules as of Jan. 1, 2010. For amateurs, generally they may continue to use their pre-2008 rules golf clubs through 2024, after which they will be required to use golf clubs that conform to the new groove design rules. However, amateurs may be impacted as early as 2011, due to the likely unavailability of pre-2008 rules golf clubs, since manufacturers will likely stop manufacturing golf clubs that have grooves according to the old groove design rules, and will likely only sell golf clubs having grooves conforming to the current groove design rules. 
     SUMMARY OF THE INVENTION 
     Golfers generally prefer iron golf clubs, particularly wedges, to be designed to produce the maximum of ball backspin. Generally, a large amount of ball backspin producing capability is desired for wedges, which are high lofted iron clubs (e.g., 45° to 70° loft angle). The large amount of ball backspin in a short distance golf shot (e.g., 5 to 100 yards) generally results in the golf ball taking a slightly lower trajectory, and stopping in a short distance upon hitting the ground, especially in soft turf conditions. In comparison, a golf club that does not produce a large amount of ball backspin results in a golf shot that has a higher trajectory, and which rolls a considerable distance beyond the point where it first hits the ground (“roll-out”). For many golfers, backspin is highly desirable for situations requiring a precise landing zone. For example, in a situation where the pin is located in a narrow portion of the green (and surround by hazards), a golf shot with large amounts of backspin is desirable because the golfer only has to consider where to land the ball, and the backspin will cause the ball to remain where it landed. In comparison, if the golfer used a wedge incapable of producing high amounts of backspin, the golfer would likely have to land the ball well before the pin, perhaps even before the green, which may result in a short shot that falls into a near-side hazard. If the golfer lands the ball on the green, the ball may roll away and trickle into a far-side hazard because of the lack of ball backspin preventing roll-out. 
     Further, if the golfer is highly skilled, the golfer&#39;s swing in combination with a high backspin producing wedge may cause the golf ball to land on the green, and then reverse course. Reversing course with the golf ball is desirable in situations where the golfer is short-sided, (i.e., the pin is very close to the edge of the green closest to the golfer, such that there is little distance between the start of the green and the pin, when measured in the distance and direction from the golfer to the pin). When short-sided, if the golfer can produce enough backspin for the ball to reverse course, the golfer then has the benefit of landing the ball anywhere behind the pin, and the ball will reverse course and roll backwards towards the pin. Without the ability to produce sufficient backspin to reverse course, the only recourse is for the golfer to land the ball short of the pin, hopefully without falling into a near-side hazard—otherwise, if the golfer lands the ball on the green, it will likely roll-out and roll well past the pin. Thus, it can be seen that a high ball backspin producing wedge is desirable for accuracy, in causing the ball to remain (“stick”) approximately where it lands (or reverse course). 
     Various groove geometries, materials, and surface finishes have been implemented in order to achieve greater ball backspin on iron golf clubs, especially for wedges. With respect to groove geometries, a larger groove width and a larger groove depth generally results in greater ball backspin. Larger groove volume also generally results in greater ball backspin. Groove geometries where the radius between the groove side wall and the golf club striking face is small and sharp generally results in greater ball backspin. With respect to materials, softer materials including elastomeric ones generally create greater ball backspin. With respect to surface finishes, with a rougher finish, generally the result is greater ball backspin. These design differences achieve greater ball backspin by generally either increasing the friction between the ball and the golf club, or by reducing the interference of friction-reducing artifacts, such as channeling away water and debris using large volume grooves. 
     However, as discussed above, the USGA and R&amp;A rules limit the design of grooves and surface finishes for golf irons and wedges, specifically with the goal to limit the ball back-spinning ability of today&#39;s modern golf clubs. Thus, some golf club head designs that result in high backspin are deemed to be nonconforming—for example, golf club irons and wedges with: grooves dimensioned larger than the USGA rules; grooves having a radius between the striking face and groove side wall smaller and sharper than specified by the USGA rules; striking faces made of a nonmetallic material such as rubber; striking face surface roughness exceeding the USGA rules. In the interest of complying with the USGA rules and marketability, most manufacturers are designing and selling only golf club irons and wedges that are fully conforming. Therefore, in today&#39;s golf club marketplace, generally the only clubs available to a golfer, even if the golfer desires to use nonconforming clubs, are those that comply with the spin-reduced, post-2008 USGA rules. 
     While golf irons and wedges are not designed for as much precision as a putter, golf irons and wedges are nevertheless scoring clubs, as opposed to drivers and woods, which are distance clubs. That is, with irons (and especially wedges), a golfer intends to land the ball as close to the target (or pin) as possible, while with woods, the golfer intends to gain as much distance as possible. When using irons and wedges, the golfer assumes that the closer the golfer is to the pin, the closer the golfer&#39;s shot should land to the pin. For example, if a golfer is 170 yards away, the golfer may use a 5-iron (e.g., 29°) to traverse that 170 yard distance. The golfer&#39;s expectation may be that the golfer expects the ball to land anywhere on a 15 yard radius green, and not in any adjacent hazard. However, if the same golfer is only 100 yards away, the golfer may use a pitching wedge (e.g., 48°) to traverse that distance, but the golfer&#39;s expectation will be that the ball should land within 25 feet of the pin, and not just anywhere on the green. 
     In the short game, a golfer typically uses high lofted wedges, and because the distance to the target is shorter, the expectation of the result is proportionally greater. For example, if the same golfer is only 40 yards away from the pin, the golfer may use a sand wedge (e.g., 54°) and expect to land the golfer&#39;s ball within 15 feet of the pin. However, if the same golfer is only 15 yards away from the pin, the golfer may use a lob wedge (e.g., 60°) and expect to land the golfer&#39;s ball within 5 feet of the pin. 
     Given the proportionally greater expectation for precision with higher lofted wedges, the ball back-spinning ability of the wedges is very important. The ball back-spinning ability of the wedges is even more important when used to escape a bunker or rescue a ball from the heavy rough. For example, when striking a ball from the heavy rough, grass and water will typically be trapped between the ball and striking face upon impact. The grass and water will dramatically reduce the resulting ball backspin, because they interfere with the clean, friction-producing striking face of the golf club. However, large grooves on a golf club may allow the grass and water to be channeled away, thereby resulting in greater ball spin than with smaller grooves. However, even with large grooves, it is often the case that a ball hit from the rough will have less backspin than the same ball hit from the fairway, because inevitably some grass and water will interfere with the striking face of the club. 
     As it is evident to the golfer of ordinary skill in the art, golf is as much a mental challenge as it is a physical challenge. The mental aspect can be highlighted in the frequent occasions where a golfer misses a critical five foot putt (perhaps for a championship win)—where five foot putts in noncompetition situations are consistently made, even by young children. Especially with respect to golf irons and especially wedges, it is imperative for the golfer to have the utmost confidence in the golfer&#39;s clubs. For example, for distance control, a golfer may demand that the golfer&#39;s 7 iron (e.g., 36°) travels precisely 150 yards, and the golfer&#39;s 8 iron (e.g., 40°) exactly 10 yards less at 140 yards. For wedges that are specialized for the short game, distance control is even more important. For example, the golfer may demand that for a 15 yard chip shot, the golfer&#39;s sand wedge (e.g., 54°) travels 7.5 yards in the air, and rolls 7.5 yards after landing, while if the golfer used the golfer&#39;s lob wedge (e.g., 60°), the golfer may expect the ball to travel 10 yards in the air, and roll 5 yards. Thus, the consistent performance of a golfer&#39;s golf clubs inspire confidence, which usually leads to better accuracy and scores. 
     In addition to confidence from consistently performing golf clubs, the golfer gains confidence from golf clubs that generally inspire confidence due to their design. For example, a large, 460 cc driver may instill confidence in a golfer because the large club head looks like the golfer can swing for the fences and never worry about mis-hitting or missing the ball. Similarly, for golf irons and especially wedges, large grooves inspire confidence because the golfer is convinced that the club will generate massive amounts of ball backspin, allowing the golfer to precisely hit the golfer&#39;s target and not roll-out. Moreover, design features that emphasize the large grooves, such as contrasting colors, will further instill confidence by making the large grooves appear even bigger than they are physically. 
     As discussed above, the USGA rules limit the size of the grooves, and therefore, the groove geometries are generally the same (i.e., at the maximum dimensions) between manufacturers. The USGA and R&amp;A rules concerning surface roughness and groove geometry should not be considered as limitations to any embodiments discussed in this application, except where expressly acknowledged as a limitation. However, considering the mental aspect of the golf game, Applicants have determined that there is a distinct, confidence-building advantage in creating the appearance that the grooves are larger than they physically are, without breaking the USGA rules, resulting in a conforming golf club. 
     In one embodiment of the invention, the grooves of a golf club iron head are surrounded by groove enhancement areas that have a surface finish identical to that of the grooves, but different from the remainder of the striking face. This results in the appearance that the grooves are as large as the grooves plus the surrounding groove enhancement areas, without breaking the USGA design rules. For instance, the confidence derived from the perception that the grooves are larger than they are physically, could cause a golfer to hit the ball with more purposeful intent. That is, to confidently hit the ball with an accelerating blow, which will produce a good amount of ball backspin—as opposed to glancing the ball with a decelerating swing, which leads to a lack of ball backspin, which may be the case if the golfer lacks confidence in his golf club. 
     In another embodiment, the grooves themselves have a surface finish identical to that of the striking face, and the groove enhancement areas surrounding the grooves have a second surface finish that emphasizes the grooves. In another embodiment, only the bottom of the grooves themselves have a surface finish identical to that of the striking face, and the side walls of the grooves and the groove enhancement areas surrounding grooves have a second surface finish that emphasizes the grooves. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention is described with reference to the accompanying drawings, in which like reference characters reference like elements, and wherein: 
         FIG. 1  is an elevational view of an embodiment of the golf club head of the invention, when viewed in a direction tangent to the striking face of the golf club head; 
         FIG. 2  is a left elevational view of an embodiment of the golf club head of the invention; 
         FIG. 3  is a close up view of an embodiment of the golf club head of the invention, showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face; 
         FIG. 4  is a close up view of another embodiment of the golf club head of the invention, showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face; 
         FIG. 5  is a close up view of another embodiment of the golf club head of the invention, showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face; 
         FIG. 6  is a cross-sectional view of an embodiment of the golf club head of the invention, corresponding to section  6  of  FIG. 1 , showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face; 
         FIG. 7  is a cross-sectional view of another embodiment of the golf club head of the invention, corresponding to section  7  of  FIG. 1 , showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face; 
         FIG. 8  is a cross-sectional view of another embodiment of the golf club head of the invention, corresponding to section  8  of  FIG. 1 , showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values, and percentages, such as those for amounts of materials, moments of inertias, center of gravity locations, and others in the following portion of the specification, may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following description and claims are approximations that may vary depending upon the desired properties sought to be obtained by the invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in any specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used. 
       FIG. 1  is an elevational view of an embodiment of the golf club head of the invention, when viewed in a direction tangent to the striking face of the golf club head. FIG.  2  is a left elevational view of an embodiment of the golf club head of the invention. In  FIGS. 1 and 2 , the golf club head  1 , is comprised of a toe  2 , heel  3 , sole  4 , top line  5 , hosel  6 , and back  7 . Further, the club has a striking face  11 , which contacts the ball at impact. The golf club head is shown as having four regions when viewed from this perspective. The region denoted by  10  is called the impact area, which is at the center portion of the striking face and is intended to be where the golf ball contacts the club at impact. Region  20  is the toe region of the golf club and is separated from the impact area by the demarcation  21 . Heel region  30  is separated from the impact area by the demarcation  22 . The hosel region is indicated by region  40  and is not intended to incur impact with the golf ball. Instead, the golf club head is attached to a golf club shaft (not shown) through mechanical connection in this hosel area. 
     Further, the impact area contains at least one groove  12 , and preferably a plurality of grooves. In one embodiment, at least one groove  12  is on the striking face, and is oriented horizontally such that the groove extends from heel to toe. Further, the groove  12  is surrounded by a groove enhancement area  13 , which is also on the striking face. In other embodiments a plurality of grooves are surrounded by a plurality of groove enhancement areas. In some embodiments, groove enhancement area  13  roughly resembles the width and height of the encapsulated groove, although the groove enhancement area has a predetermined height and width that is larger than the height and width of the encapsulated groove. Further, the groove enhancement area  13  can have a different surface finish compared to the remainder of the striking face  11  and/or a different surface finish compared to the groove  12 . The differences in the surface finish between the groove enhancement area  13 , groove  12 , and the striking face  11  allow for certain design advantages over the conventional golf club head that has a single surface finish for the entire striking face or the entire striking face and the grooves. Further, the toe area  25  and heel area  26  can have a surface finish, which may be the same or different from the surface finish of the groove enhancement area  13 , groove  12 , and the striking face  11 . Generally, two adjacent groove enhancement areas  13  that surround two adjacent grooves  12  are separated with the surface finish of the striking face  11 . That is, generally, two adjacent groove enhancement areas  13  do not touch one another—so as to form one larger groove enhancement area. 
       FIG. 3  is a close up view of an embodiment of the golf club head of the invention, showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face.  FIG. 3  is not drawn to scale, but is a representation of one embodiment of the golf club. In  FIG. 3 , the striking face  11  contains at least one groove  12  that is oriented on the striking face, extending in the heel to toe direction. The groove  12  is surrounded or encapsulated by at least one groove enhancement area  13 , which is oriented on the striking face. The groove  12  is defined by a height H 1    31 , and a width W 1    35 . The groove  12  has an upper sidewall  15 , lower sidewall  14 , and two end walls  16  and  17 . These walls define the geometry of the groove, along with the depth of the groove (not shown). In this embodiment, the groove  12  is rectangular. 
     The groove enhancement area  13  is defined by a height H 2    32 , and a width W 2    36 . The groove enhancement area  13  is bounded by and upper line  42 , a lower line  41 , and two end lines  44  and  43 . These lines define the contour of the groove enhancement area  13 . The distance between the lower sidewall  14  of one groove and the upper sidewall  15  of a second adjacent groove is defined by SP 2    34 . The distance between the lower line  41  of one groove enhancement area, and the upper line  42  of a second adjacent groove enhancement area, is defined by SP 1    33 . In this embodiment, the groove enhancement area  13  is rectangular. The groove pitch is defined as H 1    31  plus SP 2    34 , which is the distance between the upper sidewalls  15  of two adjacent grooves. The groove enhancement area pitch is defined as H 2    32  plus SP 1    33 , which is the distance between the upper lines  42  of two adjacent groove enhancement areas. In one embodiment, the groove pitch and the groove enhancement area pitch are equal. 
     The vertical span of the groove enhancement area  13  is defined as (H 2 −H 1 )/2. The horizontal span of the groove enhancement area  13  is defined as (W 2 −W 1 )/2. In some embodiments, the horizontal span and vertical span of groove enhancement area  13  are the same. In one embodiment, the horizontal span is equal to the vertical span, which are both equal to the height of the groove  12 . In other embodiments they may be different. In other embodiments, the groove enhancement area  13  is not directly centered around groove  12 . For example, the upper vertical span of groove enhancement area  13  may be larger than the lower vertical span of groove enhancement area  13 , but may be both smaller than the horizontal span of groove enhancement area  13 . Similarly, the horizontal spans of the toe side and of the heel side of the groove enhancement area  13  may be different. 
     In some embodiments, the ratio of H 1    31  to H 2    32  may be 1:3, while in other embodiments, the ratio is 1:1.1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:4 or 1:5. In some embodiments, the ratio of W 1    35  to W 2    36  may be 95:100, while in other embodiments, the ratio is 85:100, 90:100, 92.5:100, 97.5:100 or 99:100. In some embodiments, the ratio of SP 1    33  to H 2    32  (which would affect H 1    31  and SP 2    34 ) may be 1:3, while in other embodiments, the ratio is 4:1, 3:1, 2:1, 1.5:1; 1.25:1, 1.1:1, 1:1, 1:1.1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:4 or 1:5. In some embodiments, the ratio of the groove enhancement area  13  to the area of the encapsulated groove  12  is 2:1, while in other embodiments, the ratio is 0.1:1, 0.25:1, 0.5:1, 0.75:1, 1:1, 1.25:1, 1.5:1, 2.5:1, 3:1, 4:1, 5:1. In some embodiments, the ratio of the striking face area (defined as SP 1 ×W 2 ) between adjacent groove enhancement areas  13  to the combined area of one groove enhancement area  13  plus the area of the encapsulated groove  12  is  1 : 3 , while in other embodiments, the ratio is 4:1, 3:1, 2:1, 1.5:1; 1.25:1, 1.1:1, 1:1, 1:1.1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:4 or 1:5. 
     As discussed above, the groove  12  or grooves  12  are described to be “on” or “oriented on” the striking face. The use of the terms “on” and “oriented on” in this context refers to the fact that the grooves  12  are recesses that are formed (e.g., milled, cast, etched, etc.) on or into the striking face. The groove  12  or grooves  12  are not said to be “on” or “oriented on” the striking face such that the lower wall of the groove  12  (i.e., the wall that defines the depth of the groove) is co-planar with the striking face. In addition, the groove enhancement area  13  or areas  13  are also described to be “on” or “oriented on” the striking face. The use of the terms “on” and “oriented on” in this context refers to the fact that the groove enhancement area  12  are located on the striking face, but not necessarily co-planar with the striking face. With respect to the relationship of the groove enhancement area  13  with the striking face  11 , in some embodiments, the groove enhancement area  13  is co-planar with the striking face  11 . In some embodiments, the groove enhancement area  13  is substantially co-planar with the striking face  11 , with the difference being such that the surface roughness as measured in the combined areas of the striking face  11  and the groove enhancement area  13  does not exceed the maximum allowable surface roughness value set forth by the USGA or R&amp;A rules. In some embodiments, the groove enhancement area  13  is substantially co-planar with the striking face  11 , but that the surface roughness as measured in the combined areas of the striking face  11  and the groove enhancement area  13  exceeds the maximum allowable surface roughness value set forth by the USGA or R&amp;A rules. In some embodiments, the groove enhancement area  13  is not co-planar with the striking face  11 , and can be considered to form a portion of the groove  12  or grooves  12 . Some embodiments comply with the USGA and R&amp;A rules concerning surface roughness and groove geometry, as discussed above, while other embodiments do not comply with the USGA and R&amp;A rules. The USGA and R&amp;A rules concerning surface roughness and groove geometry should not be considered as limitations to any embodiments discussed in this application, except where expressly acknowledged as a limitation. 
     In one embodiment, the striking face  11  has a first surface finish, the groove  12  has a second surface finish, and the groove enhancement area  13  has a third surface finish. In some embodiments, the second surface finish for the groove  12  and the third surface finish for the groove enhancement area  13  are the same, while the first surface finish for striking face  11  is different. In some embodiments, the first, second and third surface finishes are all different. In other embodiments the first surface finish for the striking face  11  and the second surface finish for the groove  12  are the same, while the third surface finish for the groove enhancement area  13  is different. 
     In embodiments where the third surface finish of the groove enhancement area  13  is the same as the second surface finish of the groove  12 , but are different from the first surface finish of the striking face  11 , the similar surface finishes of the groove enhancement area  13  and groove  12  give the appearance that the grooves are visibly larger than they are physically. This is especially true when there is a large contrast between the similar surface finishes of the groove enhancement area  13  and groove  12  relative to the surface finish of the striking face  11 . For example, the surface finish of the striking face  11  may be a dark or black surface finish with a matte texture, while the surface finishes for the groove enhancement area  13  and groove  12  are of a bright, smooth metallic finish. 
     In embodiments where the first surface finish of the striking face  11  is the same as the second surface finish of the groove  12 , but are different from the third surface finish of the striking face  11 , the difference surface finish of the groove enhancement area  13  visibly highlights and surrounds the groove  12 . Again, the visual effect of the two different surface finishes can be enhanced by using a large contrast between the two surface finishes. For example, the surface finish of the striking face  11  and groove  12  may be a dark or black surface finish with a matte texture, while the surface finish for the groove enhancement area  13  is of a bright, smooth metallic finish. This gives the golf club head the visual appearance that there are many grooves present on the striking face. A similar but reverse effect can be achieved by using a bright, smooth metallic finish, such as chrome plating for striking face  11  and groove  12 , but using a dark or black surface finish for groove enhancement area  13 . 
     Further, in another embodiment, the differences in the surface finishes may depend only on the surface roughness and not on the color. For example, the surface finishes of the striking face  11 , groove  12  and groove enhancement area  13  may be of one color. However, the groove  12  and groove enhancement area  13  may be of a smooth or shiny appearance, while the striking face  11  may be of a rough or heavily textured appearance, which may be desirable to produce increased friction to create more ball backspin. Yet, the similar shiny appearance of grooves  12  and groove enhancement area  13  provide the impression that the grooves are larger than they are physically. In another embodiment, the groove  12  may be of a smooth or shiny appearance, while the striking face  11  and groove enhancement area  13  may be of a rough or heavily textured appearance. In another embodiment, the groove enhancement area  13  may be of a smooth or shiny appearance, while the striking face  11  and groove  12  may be of a rough or heavily textured appearance. In another embodiment, the striking face  11  may be of a smooth or shiny appearance, while the groove  12  and groove enhancement area  13  may be of a rough or heavily textured appearance. In one embodiment, a smooth surface finish may have a surface roughness of less than 120 μin. In another embodiment, a smooth surface finish may have a surface roughness of less than 50 μin. In another embodiment, a smooth surface finish may have a surface roughness of less than 30 μin. In another embodiment, a smooth surface finish may have a surface roughness of less than 5 μin. In another embodiment, a smooth surface finish may have a surface roughness of about 5 μin. In one embodiment, a rough surface finish may have a surface roughness of greater than 120 μin. In one embodiment, a rough surface finish may have a surface roughness of greater than 200μin. In one embodiment, a rough surface finish may be greater than 500μin. In the embodiments disclosed in this application, surface roughness (e.g., 120μin) is technically known as the average surface roughness, R a , which is defined as: 
               R   a     =       1   n     ⁢       ∑     i   =   1     n     ⁢           ⁢          y   i                    
The average surface roughness, R a , can be considered to be the arithmetic average of the absolute values of the vertical deviation of the roughness profile from the mean line. Again, some embodiments comply with the USGA and R&amp;A rules concerning surface roughness as discussed above, while other embodiments do not comply with the USGA and R&amp;A rules. The USGA and R&amp;A rules concerning surface roughness should not be considered as limitations to any embodiments discussed in this application, except where expressly acknowledged as a limitation.
 
     In another embodiment, either or both of the groove  12  and groove enhancement area  13  may have an unplated surface finish. That is, the base material of the golf club head in groove enhancement area  13  and groove  12  is exposed to the surrounding or ambient air, while the remainder of the striking face  11  is plated. This results in a golf club head that has a general plated appearance, except that the grooves  12  and groove enhancement area  13  will become rusty over time. For some golfers, the appearance of rust is a desirable feature, because generally the surface finish of the rust has greater friction than a smooth plated surface finish. Thus, in this embodiment, the rusty grooves  12  and rusty surrounding groove enhancement area  13  gives the impression of increased friction resulting in increased ball backspin. The actual increase in friction due to the rust may not be much greater than without, due to the small-sized nature of the groove enhancement area having the rusty surface finish. In other embodiments, only the groove enhancement area  13  is unplated, while the groove  12  and striking face  11  are plated, resulting in rust being created in the groove enhancement area  13  while the remainder of the club does not rust. 
     One benefit of the selective rusting in groove enhancement area  13  and/or groove  12  is the appearance of rust itself in the impact region that matters most (or at least matters most in impression), and no rust forming on the remainder of the golf club head, including other portions of the striking face  11 . Some golfers like the appearance of rust in the grooves, but not on the other portions of the club head. 
     In one embodiment, additional surfaces can have a different surface finish, or be unplated to give a unique visual appearance, in accordance to the types of finishes and surface roughnesses discussed above. In one embodiment, the toe area  25  of toe region  20  and heel area  26  of heel region  30  can be unplated such that they will rust. Thus, in combination with the previous embodiment described above, the overall appearance of the striking face of the golf club head will be that the toe area  25 , heel area  26 , grooves  12  and areas  11  (or only the grooves  12 , or only the areas  11 ) will all be rusted while the remainder of the impact region  10  of the striking face  11  and the hosel region  40  will be plated and not rusted. Moreover, the opposite can be achieved. For example, the toe area  25 , heel area  26 , hosel region  40 , grooves  12 , and surrounding groove enhancement areas  13  may be plated and not rusted. Only the impact region  10 , with the exception of grooves  12  and surrounding area  11 , is rusted. This embodiment results in a rusted, high friction impact region  10 , but where the grooves  12  and surrounding groove enhancement areas  13  are highlighted because they are plated (and shiny), and where the remainder of the club including the toe area  25  and heel area  26  and hosel region  40  are plated and do not look dilapidated due to rust. In another embodiment, the finish of the club head is a thin film created using physical vapor deposition (PVD). This film (PVD finish) is deposited on top of the club head, where the impact region  10  is machine roughened to create a greater surface roughness, while other areas such as the lower surfaces of the grooves  12 , toe area  25  and heel area  26  are machined or polished to have less surface roughness. In this embodiment, the toe area  25  and heel area  26  have a surface roughness of about 7 μin, the striking face  11  within the impact region  10  (not including the groove enhancement areas  13 ) has a surface roughness of about 80 μin when measured in a parallel direction to the grooves  12 , and the lower surfaces of the grooves  12  have a surface roughness of about 15 μin. In this embodiment, the groove enhancement areas  13  surrounding the grooves  12  are added to the club head by laser etching (laser engraving) around the grooves  12  to remove the PVD finish, and results in a surface roughness of the groove enhancement areas  13  of about 77 μin when measured in a parallel direction to the grooves  12 . To illustrate the difference between the overall surface roughness of a club head striking face  11  with and without the laser-etched groove enhancement areas  13 , Applicants have determined that the striking face  11  within the impact region  10  (not including the groove enhancement areas  13 ) has a surface roughness of about 159 μin when measured in a perpendicular direction to the grooves  12 , while with the laser-etched groove enhancement areas  13 , the striking face  11  within the impact region  10  has a surface roughness of about 151 μin when measured in a perpendicular direction to the grooves  12 . Accordingly, Applicants have concluded that laser etching (laser engraving) of the PVD finish, even when confined to select regions such as the groove enhancement areas  13 , reduces the surface roughness of the striking face. 
     The surface finishes discussed above may vary depending on design choice and the examples given do not limit the types of surface finishes that may be used with this invention. Known surface finishes include: no plating or a hot oil finish that is designed to rub off, exposing the underlying metallic club head material, resulting in rust; nickel plating of various colors; anodizing of various colors; and chrome plating. Further, the surface roughness of the surface finishes discussed above may vary depending on design choice and examples given do not limit the range of surface roughness that may be used with this invention. For example, smooth or shiny surface finishes will have a small surface roughness value and will generally result in less friction. Rough, textured or matte finishes will have a larger surface roughness value and will generally result in more friction. Further the striking face of the golf club head may be textured, milled, cast, or otherwise created to have surface features or patterns that would create greater friction when compared to a similar striking face with the same measured surface roughness but without the textured, milled, cast or otherwise created surface features or patterns. 
       FIG. 4  is a close up view of another embodiment of the golf club head of the invention, showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face.  FIG. 4  is not drawn to scale, but is a representation of one embodiment of the golf club. The embodiment shown in  FIG. 4  is similar to the embodiment shown in  FIG. 3 , with the exception that the grooves  12  are oblong instead of rectangular, and the groove enhancement areas  13  are oblong instead of rectangular. In  FIG. 4 , the striking face  11  contains at least one groove  12 , which is surrounded by at least one groove enhancement area  13 . The groove  12  is defined by a height H 1    31 , and a width W 1    35 . The groove  12  has an upper sidewall  52 , lower sidewall  51 , and two end walls  54  and  53  which are curved or rounded. These walls define the geometry of the groove, along with the depth of the groove (not shown). 
     The groove enhancement area  13  is defined by a height H 2    32 , and a width W 2    36 . The groove enhancement area  13  is bounded by and upper line  62 , a lower line  61 , and two end curves  64  and  63 . These lines define the contour of the groove enhancement area  13 . The distance between the lower sidewall  51  of one groove and the upper sidewall  52  of a second adjacent groove is defined by SP 2    34 . The distance between the lower line  61  of one groove enhancement area, and the upper line  62  of a second adjacent groove enhancement area, is defined by SP 1    33 . The groove pitch is defined as H 1    31  plus SP 2    34 , which is the distance between the upper sidewalls  52  of two adjacent grooves. The groove enhancement area pitch is defined as H 2    32  plus SP 1    33 , which is the distance between the upper lines  62  of two adjacent groove enhancement areas. In one embodiment, the groove pitch and the groove enhancement area pitch are equal. 
     The vertical span of the groove enhancement area  13  is defined as (H 2 −H 1 )/2. In some embodiments, the profile of the curves  63  and  64  are not concentric with the curved end walls  53  and  54  respectively. In other embodiments, the profile of the curves  63  and  64  are not circular and are instead parabolic, hyperbolic, elliptical, or comprised of two or more segments. In one embodiment, the curves  63  and  64  of groove enhancement area  13  have a profile such that the distance between the outer profile of the groove enhancement area and the groove walls are the same around the entire perimeter of the groove. In other embodiments, such as ones where the curves  63  and  64  are not concentric or not circular, this distance is not the same around the entire perimeter of the groove. 
     In some embodiments, the ratio of H 1    31  to H 2    32  may be 1:3, while in other embodiments, the ratio is 1:1.1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:4 or 1:5. In some embodiments, the ratio of W 1    35  to W 2    36  may be 95:100, while in other embodiments, the ratio is 85:100, 90:100, 92.5:100, 97.5:100 or 99:100. In some embodiments, the ratio of SP 1    33  to H 2    32  (which would affect H 1    31  and SP 2    34 ) may be 1:3, while in other embodiments, the ratio is 4:1, 3:1, 2:1, 1.5:1; 1.25:1, 1.1:1, 1:1, 1:1.1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:4 or 1:5. In some embodiments, the ratio of the groove enhancement area  13  to the area of the encapsulated groove  12  is 2:1, while in other embodiments, the ratio is 0.1:1, 0.25:1, 0.5:1, 0.75:1, 1:1, 1.25:1, 1.5:1, 2.5:1, 3:1, 4:1, 5:1. In some embodiments, the ratio of the striking face area (defined as SP 1 ×W 2 ) between adjacent groove enhancement areas  13  to the combined area of one groove enhancement area  13  plus the area of the encapsulated groove  12  is 1:3, while in other embodiments, the ratio is 4:1, 3:1, 2:1, 1.5:1; 1.25:1, 1.1:1, 1:1, 1:1.1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5, 1:4 or 1:5. 
       FIG. 5  is a close up view of another embodiment of the golf club head of the invention, showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face.  FIG. 5  is not drawn to scale, but is a representation of one embodiment of the golf club.  FIG. 5  is similar to  FIG. 3  and  FIG. 4 , except that here, a combination of a rectangular groove  12  and an oblong groove enhancement area  13  are shown. The profile of the groove walls is shown by  71  and the outer contour of the groove enhancement area  13  is shown by  72 . In another embodiment, the groove  12  has an oblong profile as described in  FIG. 4 , and the groove enhancement area  13  has a rectangular contour as described in  FIG. 3 . 
       FIG. 6  is a cross-sectional view of an embodiment of the golf club head of the invention, corresponding to section  6 - 6  of  FIG. 1 , showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the striking face  11 .  FIG. 6  is not drawn to scale, but is a representation of one embodiment of the golf club. In this view, the top line of the club is oriented to the left of the view, and the sole is towards the right. The underlying golf club head body  110  is comprised of a first material, typically a metal or metallic alloy. The golf club head has a striking face  11  and grooves  12 . The surrounding groove enhancement area  108  corresponds to groove enhancement area  13  discussed above, and is adjacent the top and bottom sidewalls of the grooves  12 . The first groove  12  has a lower surface  104  and a top and bottom side wall  106 . The second groove  12  has a lower surface  105  and a top and bottom side one  107 . In one embodiment, the striking face  11  generally has a first surface finish  101 ,  102  and  103 , while the surfaces  104 ,  105 ,  106 ,  107  and  108  have no surface finish, such that the underlying material  110  is exposed, resulting in a rusty finish. The first surface finish can be any known surface finish, such as the ones discussed above. For example, first surface finish  101 ,  102  and  103  may be a black nickel finish or a shiny chrome finish. This finish has a thin, but certain thickness. In one embodiment, one method of creating the design is to plate the entire golf club head striking face with one surface finish, then laser etch (or laser engrave) the surface finish off from surfaces  104 ,  105 ,  106 ,  107  and  108 . Other known methods of removing surface finishes or plating may be chemical etch, milling, polishing, or other mechanical means of removal. In another embodiment, the similar design may be achieved by selectively plating the golf club head striking face, or by masking off surfaces  104 ,  105 ,  106 ,  107  and  108 , and plating the entire golf club head striking face, and then removing the mask from the surfaces  104 ,  105 ,  106 ,  107  and  108  to expose the underlying material. 
       FIG. 7  is a cross-sectional view of another embodiment of the golf club head of the invention, corresponding to section  7 - 7  of  FIG. 1 , showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face.  FIG. 7  is not drawn to scale, but is a representation of one embodiment of the golf club. In this view, the top line of the club is oriented to the left of the view, and the sole is towards the right.  FIG. 7  is similar to  FIG. 6 , except that the surfaces of the grooves  12  are now plated and have a second finish  124  and  125 . Thus, the lower surfaces of the grooves  12  including the finish is  122  and  123  respectively, and the sidewalls of the grooves  12  including the finish is  120  and  121  respectively. 
     In one embodiment, the striking face  11  generally has a first surface finish  101 ,  102  and  103 , while the surfaces  104 ,  105 ,  106 ,  107  and  108  have a second surface finish. The surface finishes can be any known surface finish, such as the ones discussed above. For example, first surface finish  101 ,  102  and  103  may be a black nickel finish. This finish has a thin, but certain thickness. Surfaces  104 ,  105 ,  106 ,  107  and  108  may have a second finish, such as a chrome finish. In designs where two separate finishes are contemplated, a selective plating or masking procedure may be used to plate the surfaces  104 ,  105 ,  106 ,  107  and  108  with the second surface finish, while not selectively plating or masking off the striking face to retain the surface finishes  101 ,  102  and  103 . In a similar manner, a particular surface roughness can be achieved for the surfaces  104 ,  105 ,  106 ,  107  and  108 , while a different surface roughness is given to the remainder of the striking face  11 . Selective etching or mechanical methods may be employed to roughen or smooth particular surfaces, such as surfaces  104 ,  105 ,  106 ,  107  and  108 , while a different surface roughness can be achieved by selectively etching or selectively using mechanical methods to separately roughen or smooth the remainder of the striking face. 
     In one embodiment, the surface finishes  101 ,  102  and  103  creating striking face  11  is the same as the surface finish  124  and  125  within the grooves, while only surface  108  exposes the underlying base metal  110 , which will rust. In another embodiment, the surface finish  101 ,  102  and  103  creating striking face  11  is different from the surface finish  124  and  125  within the grooves. In another embodiment, the plating for two adjacent grooves  12  and their surrounding groove enhancement area  108  can be different. For example, surface finish  124  is different from the surface finish  125 , which are both different from surface finish for surfaces  108  (the surface finish for surfaces  108  is not depicted). In another embodiment, surface finish  124  is a first surface finish, which is different from a second surface finish  125 , and the striking face  11  may have a third finish  102  for a portion of the striking face, and a fourth finish  101  for a different portion of the striking face, and a fifth finish  103  for a different portion of the striking face. It can be seen that in combination with the disclosure above, various surface finishes for the different surfaces can be combined to create different visual effects, as well as different performance characteristics due to different surface roughnesses. 
       FIG. 8  is a cross-sectional view of another embodiment of the golf club head of the invention, corresponding to section  8 - 8  of  FIG. 1 , showing the detailed area of the striking face and two adjacent grooves and groove enhancement areas on the face.  FIG. 8  is not drawn to scale, but is a representation of one embodiment of the golf club. In this view, the top line of the club is oriented to the left of the view, and the sole is towards the right.  FIG. 8  is similar to  FIGS. 6 and 7 , except that the surfaces of the grooves  12  are now plated and have a second finish  131  and  132 , but yet the groove sidewalls  106  and  107  are unplated like surface  108 , which will rust over time. The lower surface of the grooves  12  is shown as  131  and  132 . In another embodiment, additionally one of either the top or bottom sidewalls  106  are plated, and the same corresponding sidewall in the adjacent groove is also plated  107 . In one embodiment, if the sidewalls corresponding to the sole side of the club head is chrome plated, but the sidewalls corresponding to the top line side of the club head is not plated, then at address, the lower groove surface and groove sidewall will appear smooth and shiny. However, the groove sidewalls towards the top line of the club will rust over time, which will lead to increased friction—importantly, the rusting sidewall is on the side of the groove that bites into the golf ball, while the plated side does not bite as much into the golf ball during the swing. The fact that the rust appears only on the grooves&#39; top line sidewalls, in combination with a larger appearing groove due to the chrome plating of the grooves&#39; sole side sidewalls, may give a golfer the perception that the golf club will produce a great amount of friction. The rusted top line sidewalls of the groove may cause increased friction, but the increase in friction is likely to be less than that which the golfer perceives. 
     The groove designs contemplated in the embodiments of the invention are not limited to U-shaped or V-shaped grooves, or grooves only approved by the USGA. The teachings of this invention can be applied to various grooves of various geometries and designs. For example, the teachings of this invention can be applied to the following embodiments of grooves: extending horizontally from heel to toe; extending vertically from top line to sole; spiral patterned grooves; diagonally oriented grooves; grooves that overlap; circular or concentrically oriented grooves; wavy or zig-zag grooves; grooves that are oriented to form a logo or a pattern; grooves that criss-cross each other; grooves resembling the patterns of tire treads; grooves composed of individual indentations or dots. Similarly, the groove enhancement areas  13  surrounding the individual grooves are not limited to oblong or rectangular contours. Instead, the individual groove enhancement areas may be of any geometric profile, such as ones having a wavy or zig-zag outer profile line. In embodiments where the grooves themselves are not oblong or rectangular (e.g., spiral shaped, circular, etc.), the groove enhancement areas generally surround the individual grooves, but may themselves have a contour generally resembling the individual grooves (e.g., a spiral shaped groove enhancement area surrounding a spiral groove). 
     As used herein, directional references such as rear, front, lower, etc. are made with respect to the club head when grounded at the address position. See, e.g.,  FIGS. 1 and 2 . The direction references are included to facilitate comprehension of the inventive concepts disclosed herein, and should not be read as limiting. 
     While the preferred embodiments of the invention have been described above, it should be understood that they have been presented by way of example only, and not of limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. For example, while the inventive concepts have been discussed predominantly with respect to iron-type golf club heads, such concepts may also be applied to other club heads, such as wood-types, hybrid-types, and putter-types. Thus the invention should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. Furthermore, while certain advantages of the invention have been described herein, it is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.