Abstract:
A golf club head with an improved face insert is disclosed herein. More specifically, the present invention discloses a golf club head wherein the face insert has a cavity near the top surface of the face insert that extends vertically downward towards the bottom surface of the face insert while terminating short of the bottom surface. The face insert having the cavity serves to remove unnecessary weight from the upper surface weight of the face insert; while the cavity that terminates short of the bottom surface yields a solid face insert near the bottom surface to preserve the structural integrity of the face insert where the golf club head impacts a golf ball. The cavity created within the face insert may be filled in with a lightweight material that helps further maintain the structural integrity of the entire face insert while still removing unnecessary weight from the face insert.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a golf club head having an improved face insert. More specifically, the present invention relates to a golf club head with a face insert that improves the performance of the golf club head by removing unnecessary weight near the top surface of the face insert while preserving the structural integrity of the face insert near the bottom surface of the face insert, where the golf club head impacts a golf ball. The face insert disclosed by the present invention may generally have a cavity beginning near a top surface of the face insert that extends vertically into the body of the face insert terminating short of the bottom surface of the face insert; wherein the cavity may be filled with a secondary material having a second density lower than the first density of the first material used to construct the remainder of the face insert. 
       BACKGROUND OF THE INVENTION 
       [0002]    In order to improve the performance of a golf club, golf club designers constantly struggle with ways to design a golf club that could hit a golf ball longer and straighter. Despite all the benefit generally associated with being able to hit a golf ball the longer, most golfers will agree that it is the ability to hit a golf ball straighter that most dramatically increases a golfer&#39;s ability to obtain a low score. Hence, in order to hit a golf ball straighter, golf club designers have struggled with the ability of a golf club to produce a relatively straight flight even when the golf ball is not struck at the center of the golf club head; as a golf ball struck at the center of the face of the golf club head tends to already have a relatively straight flight path. In order to design a golf club that tends to be more forgiving on off-center hits, the Center of Gravity (CG) location of the golf club head as well as the Moment of Inertia (MOI) are often two of the most important factors that can help achieve such a straighter flight. 
         [0003]    Although numerous methods can be used to improve the CG and MOI of a golf club head, one of the most effective ways to improve such a performance is by removing weight from unnecessary areas of the golf club head and placing it at alternative locations within the golf club head. U.S. Pat. No. 5,407,202 to Igarashi (&#39;202 Patent) gives one example of such an attempt by disclosing a golf club head having a face insert that is made of a high strength lightweight metals such as titanium, allowing the weight saved to be distributed around the perimeter of the golf club head to improve the MOI of the golf club head. 
         [0004]    U.S. Pat. No. 5,405,137 to Vincent et al. (&#39;137 Patent) further demonstrates the applicability of this concept into a metal wood type golf club head to increase the performance of such a metal wood type golf club head. More specifically, the &#39;137 Patent discloses a golf club head comprising a body and a face insert that is positioned in a recess provided on the front part of the body, wherein the recess comprises of a plurality of abutments so as to create a stable support for the insert in the recess. 
         [0005]    In an alternative situation, U.S. Pat. No. 6,814,674 to Clausen et al. (&#39;674 Patent) shows how a face insert could be used in a iron type golf club head to improve the performance of a golf club head. More specifically, the &#39;674 Patent discloses an iron type golf club head composed of three main components: a periphery member, a central member, and a face plate; wherein the iron type golf club head has a high moment of inertia. 
         [0006]    Despite all the advancements in incorporating a face insert within a golf club head to improve the performance of a golf club head, the current art fails to truly maximize the opportunity to manipulate the composition and geometry of the face insert itself to further improve the performance of the golf club head. Even though replacing the striking face of the golf club with a face insert with a different insert that is constructed out of a lighter material will allow for significant weight savings, further weight savings and optimization of weight location could be accomplished by adjusting composition and geometry of the face insert itself. 
         [0007]    U.S. Pat. No. 5,766,094 to Mahaffey et al. (&#39;094 Patent) discloses an example of an early attempt to improve the performance of a golf club head by reducing unnecessary weight within the face insert itself. However, the method disclosed in &#39;094 Patent may not be optimal as it uniformly removes weight from the face insert by creating cavity throughout the entire face insert itself. Uniformly moving weight from a face insert is undesirable because it fails to consider the strength and durability needs of the face insert itself. Because the face insert of a golf club head is the portion of the golf club head that is subjected to the most stress, sacrificing strength and durability at such a location may generally be an undesirable solution to save weight. 
         [0008]    Hence, as it can be seen from above, despite all the advancement in golf club technology, the current art has been unable to sufficiently improve upon the performance advantages achievable by utilizing a face insert within a golf club head. Furthermore, the current art&#39;s attempt to improve upon the performance of a golf club head by focusing on the face insert itself is undesirable because it does so by uniformly taking away material within the face insert itself at the expense of sacrificing strength and durability. Ultimately, it can be seen from above that there is a need in the art to further improve upon the performance of a golf club head by focusing on improving the face insert without sacrificing the strength and durability of such a face insert. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    One aspect of the present invention is a golf club head comprising a face insert located at a frontal portion of the golf club head for striking a golf ball together with a body located at an aft portion of the golf club head. The body portion has a recessed portion wherein the recessed portion delimits the face insert such that the face insert rests within the recessed portion of the body. The face insert further comprises a core member and a cavity. The cavity is located at the top surface of the face insert extending into the face insert towards the bottom surface of the face insert, terminating short of the bottom surface. 
         [0010]    In another aspect of the present invention is a golf club head comprising a body located at an aft portion of the golf club head having a recessed portion near a frontal portion of the body, and a face insert being of a similar size and shape to said recessed portion connected to the body within the recessed portion. The face insert further comprises a core member and a filler member. The core member, made out of a first material, has a cavity near a top surface of the face insert; while the filler member, made out of a second material, fills in the cavity of the core member. The first material has a first density and the second material has a second density, wherein the second density is lower than the first density. 
         [0011]    In a further aspect of the present invention is a set of iron-type golf clubs comprising a first golf club head and a second golf club head. The first golf club head has a first loft wherein the first golf club head further comprises a first face insert having a first density, wherein the first cavity has a first volume. The second golf club head has a second loft wherein the second golf club head further comprises a second face insert having a second density, wherein the second cavity has a second volume. The first loft is greater than the second loft and the second volume is greater than the first volume. 
         [0012]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
           [0014]      FIG. 1  shows a perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0015]      FIG. 2  shows an exploded perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0016]      FIG. 3  shows a cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention taken along the middle of the golf club head; 
           [0017]      FIG. 4  shows an enlarged cross-sectional view of an face insert in accordance with an exemplary embodiment of the present invention; 
           [0018]      FIG. 5  shows an enlarged view of a cross-sectional view of a face insert in accordance with an exemplary embodiment of the present invention; 
           [0019]      FIG. 6   a  shows an cross-sectional view of a golf club head having a loft α in accordance with an exemplary embodiment of the present invention taken along the middle of the golf club head; 
           [0020]      FIG. 6   b  shows an cross-sectional view of a golf club head having a loft β in accordance with an exemplary embodiment of the present invention taken along the middle of the golf club head; 
           [0021]      FIG. 6   c  shows an cross-sectional view of a golf club head having a loft Φ in accordance with an exemplary embodiment of the present invention taken along the middle of the golf club head; 
           [0022]      FIG. 7  shows an enlarged cross-sectional view of a face insert in accordance with an exemplary embodiment of the present invention; 
           [0023]      FIG. 8  shows an enlarged cross-sectional view of a face insert in accordance with an exemplary embodiment of the present invention; 
           [0024]      FIG. 9  shows an enlarged cross-sectional view of a face insert in accordance with an exemplary embodiment of the present invention; 
           [0025]      FIG. 10  shows an enlarged cross-sectional view of a face insert in accordance with an exemplary embodiment of the present invention; and 
           [0026]      FIG. 11  shows an enlarged cross-sectional view of a face insert in accordance with an alternative exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    The following detailed description describes the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0028]    Various inventive features are described below and each can be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
         [0029]      FIG. 1  of the accompanying drawings shows a perspective view of a golf club head  100  in accordance with an exemplary embodiment of the present invention. More specifically, golf club head  100  shown in  FIG. 1  may have a face insert  102  that is located at a frontal portion of the golf club head that can be used for striking a golf ball. The face insert  102 , as shown in this current exemplary embodiment, may generally be connected to the frontal portion of a body  104  of the golf club head  100  in a way that the body  102  makes up the aft portion of the golf club head  100  to provide structural support for the face insert  102  itself. 
         [0030]    Although the perspective view of the golf club head  100  shown in  FIG. 1  shows an assembled view of the golf club head  100 , the exploded view of golf club head  200  in  FIG. 2  allows a clearer view of the connection between the face insert  202  with the body  204 . More specifically, the exploded view of golf club head  200  shows the body  204  of the golf club head  200  having a recessed portion  206  that creates a pocket within the body  204  that matches in size and shape with the perimeter of the face insert  202 . Alternatively speaking, it can be stated that the recessed portion  206  delimits the face insert  202  such that the face insert  202  rests within the recessed portion  204  of the golf club head  200  without departing from the scope and content of the present invention. In addition to showing the recessed portion  206 , the exploded view of the golf club head  200  also shows a backing portion  207  to the recess portion  206 , wherein the backing portion  207  provides a backstop to the face insert  202  as it is inserted into the recessed portion  204 . 
         [0031]    The exploded view of golf club head  200  shown in  FIG. 2  of the accompanying drawings also may also show a cavity  212  within the face insert  202  in order to improve the overall performance of the golf club head  200 . Cavity  212 , as shown in the current exemplary embodiment, may generally be formed near the top surface of the face insert  202  extending vertically downward into the body of the face insert  202  towards the bottom surface of the face insert  202 . Having a cavity  212  in this orientation improves the performance of the golf club head  200  by removing unnecessary weight from portions of the face insert  202  that is not subjected to the highest stresses, allowing this weight to be repositioned at a more optimal position within body  204  of the golf club head. 
         [0032]      FIG. 3  of the accompanying drawings shows a cross-sectional view of the golf club head  300 , taken down the middle of the golf club head  300 , in accordance with an exemplary embodiment of the present invention. It should be noted that all subsequent cross-sectional view of golf club heads will be taken down the middle of the golf club head, and all dimensional references will be referring to the measurement of the various dimensions at the mid point of the golf club head viewed from this cross-sectional line. The cross-sectional view of golf club head  300  allows for a clearer view of the cavity  312  within the face insert  302  as well as how the face insert  302  fits within the recessed portion  306  of the body  304 . More specifically,  FIG. 3  shows how the recessed portion  306  creates a pocket for the face insert  302  and demits the face insert so that it rests within the recessed portion  306 . It should be noted that the recessed portion  306  works in conjunction with the backing portion  307  to fully create a pocket that supports the face insert  302  without departing from the scope and content of the present invention. In addition to the above, it should be noted that the cavity  312  within the face insert  302  essentially divides the face insert  302  in to a solid core member  310  and a hollow cavity  312  to improve the performance of the golf club head  300  as mentioned above. 
         [0033]    In order to provide a clearer view of the relationship between the core member  310  and the cavity  312  of the face insert  302 ,  FIG. 4  is provided to show an enlarged cross-sectional view of the face insert  302  originally shown in  FIG. 3 . Face insert  402  shown in  FIG. 4  may generally have a frontal surface  420  containing a plurality of scorelines  421 , a rear surface  422  directly parallel to the frontal surface  420  and behind the frontal surface  420 , a top surface  424  perpendicular to the frontal surface  420  and the rear surface  422  near the top of the face insert  402 , and a bottom surface  426  also perpendicular to the frontal surface  420  and the rear surface  422  near the bottom of the face insert  402 . The various surfaces  420 ,  422 ,  424 , and  426  help provide a frame of reference for the orientation and direction of the cavity  412  within the face insert  402 . In this exemplary embodiment, the cavity  412  is formed at the top surface  424  of the face insert  402  and extends vertically into the face insert  402  towards the bottom surface  426  of the face insert  402 , terminating short of the bottom surface  426 . 
         [0034]      FIG. 4  of the accompanying drawings also shows how the cavity  412  bifurcates the face insert  402  into a core member  410  and the cavity  412 . As indicated above, the bifurcation of the face insert  402  into a core member  410  and a cavity  412  helps retain the strength and durability of the face insert  402  near the bottom surface  426  of the golf club head while removing weight near the top surface  424  of the golf club head. Retaining the strength and durability of the face insert  402  near the bottom surface  426  may be desirable because it is generally the location where the face insert  402  impacts a golf ball, hence it is also the portion of the face insert  402  that is subjected to the most stress. Removing weight near the top surface  424  of the face insert  402  of the golf club head  400  may be desirable because that portion of the face insert  402  does not generally impact a golf ball; hence it is also the portion of the face insert  402  that is subjected to the least amount of stress. 
         [0035]    In order to quantify the bifurcation of the face insert  402  into the core member  410  and the cavity  412 , a relative thickness ratio is created to determine that is derived from the relative thicknesses of the core member  410  to the cavity  412 . More specifically, the relative thickness ratio may be defined as the thickness of the cavity  412  divided by the thickness of the core member  410  at a distance d 1  of ½ an inch away from the top surface  424  of the golf club head shown below in Eq. (1): 
         [0000]    
       
         
           
             
               
                 
                   
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                       Cavity 
                     
                     
                       Thickness 
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                       of 
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                        
                       Core 
                        
                       
                           
                       
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                       Member 
                     
                   
                 
               
               
                 
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         [0000]    In one exemplary embodiment of the present invention, the face insert  402  of the golf club head may have a thickness ratio of greater than about 0.20 and less than about 0.80, more preferably greater than about 0.30 and less than about 0.80, and most preferably greater than about 0.40 and less than about 0.80. 
         [0036]    Although the thickness ratio discussed above may shed an insight on the amount of weight that can be removed from the cavity  412  of the face insert  402 , it may also help in quantifying the size and shape of the cavity  412 . More specifically, the cavity  412  shown in this embodiment of the present invention may generally be the thickest near the top surface  424 , while constantly decreasing in thickness as it gets closer to the bottom surface  426 . Alternatively speaking, the thickness ratio of the face insert  402  is the highest near the top surface  424  and the thickness ratio of the face insert  402  changes and decreases from the top surface  424  towards the bottom surface  426 . It should also be noted that in this exemplary embodiment of the present invention, the thickness ratio of the face insert  402  may decreases linearly starting from said top surface  424  towards said bottom surface  426  to smooth transition the change in the thickness ratio. 
         [0037]    Although the cavity  412  shown in  FIG. 4  may be hollow, in a preferred embodiment of the present invention, the cavity  412  may be filled with a lightweight material that provides both weight savings benefits as well as some additional level of structural support of the face insert  402  near the top surface  424 , especially when compared to a purely hollow cavity  412 .  FIG. 5  of the accompanying drawings provides a cross-sectional view of a face insert  502  in accordance with the preferred embodiment of the present invention wherein the cavity  512  is filled in with a lightweight material  513  that is capable of providing some additional level of structural support as well as removing weight from the cavity  512  portion of the face insert  502 . More specifically, the core member  510  may generally be made out of a first material while the cavity  512  may generally be filled with a second material that is different from the first material. Alternatively speaking, the face insert  502  may be classified into two separate and distinct components, a core member  510  and a filler member  513  in this embodiment of the present invention. 
         [0038]    Because the first material may generally need to strong enough to withstand the impact forces with a golf ball, the first material may generally have a higher density, while the second material used to remove weight near the top surface  524  of the face insert may generally have a lower density. More specifically, the first material, as disclosed in this current exemplary embodiment, may generally be steel or titanium for its strength and durability characteristics; however, numerous other materials may be used so long as it provides sufficient strength to withstand the impact forces with a golf ball all without departing from the scope and content of the present invention. The second material used to create the filler member  513  within the cavity  512 , on the other hand, may generally be a composite type material, an aluminum type material, a rubber type material, a plastic type material, or any other type of material that has a lower density than the first material without departing from the scope and content of the present invention. This filler member  513 , in addition to provide significant weight savings, could also provide additional benefit that could also provide vibration dampening characteristics without departing from the scope and content of the present invention. 
         [0039]      FIGS. 6   a ,  6   b , and  6   c  of the accompanying drawings show cross-sectional views of a plurality of golf club head included in a set of irons in accordance with an alternative embodiment of the present invention. More specifically,  FIG. 6   a  relates generally to a long iron type golf club head in accordance with an exemplary embodiment of the present invention having a loft of about α,  FIG. 6   b  relates generally to a middle iron type golf club head in accordance with an exemplary embodiment of the present invention having a loft of about β, and  FIG. 6   c  relates generally to a short iron type golf club head in accordance with an exemplary embodiment of the present invention having a loft of about Φ. Loft angle α may generally be less than loft angle β, which is even less than loft angle Φ. It is worth noting here that  FIGS. 6   a ,  6   b , and  6   c  show a progressive change in the size of the cavity  612  that varies with the different lofts in order to adjust for the various amount of discretionary weight needed for the various golf club heads. 
         [0040]    For example, the long iron golf club  630  shown in  FIG. 6   a  may generally have a relatively large cavity  612  filled in with the filler material  613  as longer irons may generally require a lower CG to get the golf club underneath the golf ball as well as provide more forgiveness by placing the discretionary weight saved from the face insert  630  elsewhere to improve the MOI. The middle iron golf club  632  shown in  FIG. 6   b  may generally have a medium sized cavity  612  filled in with the filler material  613  to strike a middle ground between weight savings and performance gains. The short irons golf club  634  shown in  FIG. 6   c  may generally have a smaller sized cavity  612  filled in with the filler material  613  to provide less discretionary weight, as shorter irons do not need as low of a CG nor does it require as much forgiveness. Alternatively speaking, the size of the cavities  612  may be quantified by a specific volume, which changes depending on the loft α, β, and Φ of the various iron-type golf clubs. More specifically, the volume of the cavities  612  may change inversely with the lofts α, β, and Φ of the various iron-type golf club throughout the set in such a way that the volume of the cavities  612  will decrease when the loft α, β, and Φ of the iron-type golf clubs increase. In this exemplary embodiment of the present invention, golf club  634  may have a first loft that is greater than a second loft of golf club  632 , yielding a second volume that is greater than the first volume. 
         [0041]      FIG. 7  of the accompanying drawings shows a cross-sectional view of a face insert  702  in accordance with an alternative embodiment of the present invention wherein the cavity  712  formed within the face insert  702  may have a cap  740  near the top surface  724  of the face insert  702 . Having a cap  740  in this alternative embodiment of the present invention is advantageous when the cavity  712  is filled with the filler material  713  because it provides more retention forces. The cap  740 , as shown in this current exemplary embodiment, may help retain the filler material  713  within the cavity  712  by providing more surface area for bonding between the filler material  713  and the core member  710 . Although a separate figure is not used to show in detail the variations of the size of the cavity  712  and it&#39;s accompanying filler material  713  throughout a set of iron type golf clubs, the size of the cavity  712  having a cap  740  could also change to correspond to the various needs of the various golf club heads that have different lofts as previously illustrated in  FIG. 6 . 
         [0042]      FIG. 8  of the accompanying drawings shows a cross-sectional view of a face insert  802  in accordance with an alternative embodiment of the present invention wherein the cavity  812  formed within the face insert  802  may have a cap  840  that is filled in with a different material than the filler material  813 . Filling the cavity  812  with two different materials may offer fine tune weight adjustment capabilities within the face insert  802 , which may be beneficial in certain situations requiring such a minute adjustment. Similar to the prior discussion above regarding the variations in the size and depth of the cavity  812  may have different sizes throughout the different lofts within a set of iron type golf club heads, the size and depth of the cavity  812  in accordance with this embodiment could vary throughout a set of irons to maximize the performance. 
         [0043]      FIG. 9  of the accompanying drawings shows a cross-sectional view of a face insert  902  in accordance with an alternative embodiment of the present invention wherein the cavity  912  formed within the face insert  902  may have a more rectangular shape to uniformly remove weight from the face insert  902  without departing from the scope and content of the present invention. The cavity  912  shown in  FIG. 9  may also be filled in with a filler material  913  to provide some strength and durability characteristics without departing from the scope and content of the present invention. Similar to the prior discussion above regarding the variations in the size and depth of the cavity  912  may have different sizes throughout the different lofts within a set of iron type golf club heads, the size and depth of the cavity  912  in accordance with this embodiment could vary throughout a set of irons to maximize the performance. 
         [0044]      FIG. 10  of the accompanying drawings shows a cross-sectional view of a face insert  1002  in accordance with an alternative embodiment of the present invention wherein the cavity  1012  may change its thickness ratio non-linearly from the top surface  1024  towards the bottom surface  1026  without departing from the scope and content of the present invention. Having a non-linear change in the thickness of the cavity  1012  that is filled with the filler material  1013  may be desirable in a face insert  1002  to allow for finer tune adjustment of the strength and durability of the face insert  1002  depending on the point stresses that the face insert  1002  is subjected to at various points. This non-linear change in the face thickness ratio may help optimize the correct balance between weight the strength and durability needed for a face insert  1002  together with the weight savings achievable by such a cavity  1012  that is filled in with the filler material  1013 . Similar to the prior discussion above regarding the variations in the size and depth of the cavity  1012  may have different sizes throughout the different lofts within a set of iron type golf club heads, the size and depth of the cavity  1012  in accordance with this embodiment could vary throughout a set of irons to maximize the performance. 
         [0045]      FIG. 11  of the accompanying drawings shows a cross-sectional view of a face insert  1102  in accordance with a further alternative embodiment of the present invention wherein the frontal surface  1120  is not parallel with the rear surface  1122 . Top surface  1124  may or may not be perpendicular to the frontal surface  1120 , and the bottom surface  1126  is not perpendicular to the frontal surface  1120 . Although perpendicular surfaces are used in a the preferred embodiment discussed above, the non-perpendicular surfaces may be used to further adjust the various weighting and vibration dampening needs of a golf club head all without departing from the scope and content of the present invention. 
         [0046]    Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the above specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present 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. 
         [0047]    Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the 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. 
         [0048]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.