Abstract:
A short-range golf ball made of one or more of a variety of materials in such a manner that upon exposure to natural weather conditions (such as ultraviolet solar radiation, dew, rain, wind, or dirt), the golf ball material will quickly oxidize, degrade, disintegrate, melt or otherwise decompose to leave products harmless to, or beneficial to, the natural environment. Such breakdown products should be non-toxic to animals and plants and should not contaminate water supplies, soil or other parts of the ecological system. The short-range golf ball preferably has a maximum range of less than 100 yards.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application Serial No. 60/262,481, filed Jan. 18, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to golf balls for use in practicing one&#39;s golf swing.  
         BACKGROUND OF THE INVENTION  
         [0003]    Golfers often desire to practice their golf swing. One way to practice one&#39;s golf swing is to actually play a round of golf on a golf course. However, during game play, after a golfer swings and hits a golf ball, he must travel to the place where the golf ball landed before swinging and hitting the golf ball again. As a result, during a two to four hour round of golf, a golfer typically only swings and hits a golf ball 70 to 120 times (depending largely on the skill of the golfer).  
           [0004]    Golfers may also practice their golf swing on a professional driving range. At such a driving range, golfers can rent buckets of “practice balls”, which are generally the same size and weight as standard golf balls. That is, these golf balls are typically about 1.68 inches in diameter and weigh approximately 45 grams. Golfers practice their swing by hitting the practice golf balls, in succession, into a large open field that usually contains mock golf greens, distance indicators, and targets. The balls are then collected (usually by a modified tractor) for reuse by other golfers.  
           [0005]    Practicing golf on a driving range has several advantages. First, it allows golfers to practice swing mechanics (such as keeping one&#39;s head down and not snapping one&#39;s wrists while swinging the golf club) in a controlled environment where the golfer can focus his energy on completing several swings in succession, without having to locate and recover a golf ball between swings. In addition, because practice golf balls generally have similar performance characteristics as standard golf balls, golfers can see how far a standard golf ball would travel when hit in a certain manner. In addition, golfers can use practice golf balls to ascertain the general flight characteristics that a ball will have when hit in a certain way. For example, a golfer may determine that, when striking a ball in a certain way, the ball will rise quickly and slice to the right.  
           [0006]    For background purposes, an average golfer generally hits a standard golf ball between 70 and 250 yards. The maximum range of a standard golf ball is generally between 250 and 350 yards.  
           [0007]    One disadvantage of practicing a golf swing using standard practice golf balls is that these balls travel quite far when struck with a proper swing using long clubs such as woods and low irons. Thus, practicing with a standard practice golf ball generally requires a large amount of land. In addition, because standard practice balls travel such a long way when struck with a full swing, some form of machine-assisted ball retrieval (such as retrieval by a ball-retrieval tractor) is desirable to collect the balls after they have been hit. Manually retrieving the balls would be possible, but extremely time consuming.  
           [0008]    At least one reduced-range golf ball (the “Cayman” golf ball) has been developed for use in playing golf on shortened golf courses. Such golf courses are generally located in areas, such as the Cayman Islands, were land is very scarce or expensive. Such reduced-range golf balls are designed to have essentially the same flight characteristics as a standard golf ball, but to travel approximately 50% of the distance of a standard golf ball. Thus, it is estimated that the average golfer would generally hit a reduced-range golf ball between about 40 and 150 yards. The maximum range of these reduced-range golf balls is estimated to be generally around 175 yards.  
           [0009]    As discussed in U.S. Pat. No. 4,836,552, which is directed to a reduced-range golf ball, reduced-range golf balls are generally the same size as a standard golf ball (i.e., 1.68 inches in diameter) and have the same general flight characteristics as a standard golf ball. However, to minimize their maximum range, these golf balls are typically lighter than standard golf balls. Thus, for example, the reduced-range golf ball described in U.S. Pat. No. 4,836,552 has a diameter of approximately 1.68 inches, but weighs only between 15 and 35 grams (about 32% to 78% of the weight of a standard golf ball).  
           [0010]    The advantage of reduced-range golf balls is that they allow a golfer to drive a golf ball using a full swing while playing relatively short holes. Because these golf balls are engineered to have the same general flight characteristics as standard golf ball (aside from range), these golf balls give a golfer essentially the same feedback regarding their swing as they would receive while playing with a regulation golf ball. That is, the golfer can estimate how far a standard golf ball would travel when hit in the same way as the practice golf ball, and the golfer can see whether a given swing would result in a hook, a slice, or a straight shot.  
           [0011]    As noted above, although reduced-range golf balls are designed to travel shorter distances than standard golf balls, these reduced-range golf balls still have a significantly long maximum range. For example, as noted above, the reduced-range golf ball described in U.S. Pat. No. 4,836,552 is estimated to have a maximum range of about 175 yards, which is about 50% of the range of a standard golf ball. Accordingly, a plot of land of at least approximately 150 square yards would be desirable to practice hitting this golf ball with a full swing. In addition, because it would be extremely time consuming to manually retrieve a large number of golf balls over this relatively large area of land (and because reduced-range golf balls are not biodegradable and are relatively expensive) some sort of mechanical ball retrieval system (such as a modified tractor) would be desirable to retrieve the balls after a practice session.  
           [0012]    In some settings, such as driving ranges on cruise ships, golfers practice their swing using buckets of relatively inexpensive golf balls (hereinafter referred to as “Cruise Ship” golf balls) that are designed to have the same size, weight, and flight characteristics (including maximum range) as a standard golf ball, but that are also configured to decompose after prolonged contact with water. One such golf ball is described in U.S. Pat. No. 5,356,149 to Kane.  
           [0013]    “Cruise ship” practice golf balls are advantageous because, unlike standard practice balls, they do not require retrieval. Rather, they merely dissolve over time due to prolonged exposure to a large amount of water. However, as was the case with standard practice balls and reduced-range golf balls such as the “Cayman” golf ball, a significant amount of space (at least 250 square yards) is required to practice one&#39;s golf swing using these “cruise ship” practice balls.  
           [0014]    In addition, because “cruise ship” golf balls are approximately the same size and weight as standard golf balls, they contain relatively densely-packed water-soluble material. Accordingly, a significant amount of water is apparently required to dissolve these golf balls. Also, because the golf balls are densely packed and are configured to be approximately as hard as a standard golf ball, it can be expected that these golf balls would take a significant amount of time to biodegrade after being hit into the ocean.  
           [0015]    Because cruise ships are generally surrounded by open expanses of large amounts of water, and because it is not generally essential that these golf balls dissolve quickly after being hit into the water, “cruise ship” golf balls are ideal for use on cruise ships. However, because “cruise ship” golf balls have a maximum range that is similar to a standard golf ball, practicing with these “cruise ship” golf balls on land would require a significant amount of open land. Also, because these golf balls are relatively dense, these golf balls apparently require exposure to a significant amount of water before dissolving, and may take a long period of time to dissolve. Accordingly, if these golf balls were used in an area (such as a park or a neighborhood field) where it would be regarded as unacceptable to leave a large number of golf balls for a significant period of time, a machine-assisted ball retrieval system would be required to retrieve these golf balls after practice.  
           [0016]    Because practicing on land-based or water-based driving ranges gives golfers the opportunity to practice driving a large number of golf balls of standard weight and standard size in a relatively short period of time, many golfers are willing to regularly travel to such driving ranges to practice their golf swing. However, golfers are often faced with a situation in which they have a sufficient amount of time to practice (for example 30 minutes), but do not have sufficient time to travel to a driving range, practice their golf swing, and then travel back home. In such situations, it is desirable for a golfer to be able to practice their golf swing close to home (and preferably in their own back yard).  
           [0017]    As may be understood from the above discussion of prior art golf balls, standard practice golf balls, reduced-range golf balls, and “cruise ship” golf balls are simply not suitable for practicing one&#39;s full golf swing in a residential setting. More particularly, because the range of each of these golf balls far exceeds the length of a typical back yard, a golfer would need to severely limit their swing to assure that they do not hit the golf balls outside the boundary of their property and into neighboring yards, streets, or common areas. A golfer might do this by either “choking up” on the golf club (i.e. by gripping the golf club closer to its head than they normally would), or by modifying the range of their swing so that they don&#39;t raise the club as far from the ground as they normally would before swinging. Neither of these techniques allows the golfer to practice their full swing.  
           [0018]    Also, even with a limited swing, practicing close to other homes using a standard, reduced-range, or “cruise ship” golf ball would be dangerous. This is due to the fact that, if a golfer were to mistakenly hit one of these golf balls beyond the boundaries of his yard, the golf ball could potentially injure nearby people or pets, or damage neighboring homes, cars, or landscape. In addition, because standard practice balls and reduced-range golf balls are typically expensive (and do not decompose on their own), and because “cruise ship” golf balls are relatively dense (and therefore presumably would require a substantial amount of time to dissolve under normal back-yard conditions), a golfer would need to retrieve these golf balls after a practice session. Accordingly, the golfer would either need to collect the balls manually (which could take an extensive amount of time), or invest in an automated golf ball retrieval device (such as a modified tractor). Both of these solutions would generally be undesirable.  
           [0019]    Some golfers practice their golf swing in small areas using plastic “wiffle” golf balls. These wiffle golf balls are hollow plastic golf balls that include several relatively large holes in the exterior portion of the golf ball. These golf balls are typically about the same size as a standard golf ball and, due to the fact that they consist entirely of a lightweight, thin spherical shell, these golf balls are generally much lighter than standard golf balls. Because wiffle balls are very light, their flight trajectory is determined in large part by the aerodynamic qualities of the ball. Thus, any wind acting on a wiffle ball will have a dramatic effect on the ball&#39;s trajectory. This effect is further enhanced by the holes in the outer portion of the ball, which increase the wind resistance of the ball and, thus, limit the maximum distance of the ball.  
           [0020]    Wiffle golf balls are somewhat advantageous (especially for indoor use) because, due to their extremely reduced weight, they can strike windows, furniture, cars and other fragile objects without damaging these objects. In addition, these wiffle balls pose a reduced risk to adults, children, and pets.  
           [0021]    However, there are also several disadvantages to using wiffle balls to practice one&#39;s full golf swing outdoors. First, as noted above, wind can dramatically influence the flight characteristics of wiffle balls. Thus, it is often difficult for a golfer to obtain reasonable feedback on the golfer&#39;s swing when using these golf balls to practice under even slightly windy conditions. For example, a moderate wind blowing against the golfer&#39;s back may cause each wiffle ball to automatically slice when hit, even though a standard golf ball, when hit with the same stroke, would not have a tendency to slice.  
           [0022]    A second disadvantage of using wiffle golf balls to practice outdoors is that these golf balls have a tendency to travel relatively far when driven under certain conditions. For example, a golfer hitting a wiffle ball in the presence of a reasonably strong back wind may easily be able to hit the ball 30 yards or more. Under such conditions, wiffle golf balls suffer from many of the same disadvantages that are associated with standard practice balls, reduced-range golf balls, and “cruise ship” golf balls. For example, when driven with the golfer&#39;s full swing, these golf balls may undesirably travel into neighboring yards, streets or common areas. Also, because these wiffle golf balls are made of non-biodegradable hard plastic, golfers must retrieve these balls after using the balls in a practice session. Accordingly, a golfer must either collect the balls manually (which could take an extensive amount of time), or invest in an automated golf ball retrieval device (such as a modified tractor) to mechanically retrieve the balls. As noted above, both of these solutions are undesirable.  
           [0023]    Accordingly, there is a need for a golf ball that would allow a golfer to repeatedly practice the golfer&#39;s golf swing in a small area without having to collect a large number of balls after the practice is complete.  
         SUMMARY OF THE INVENTION  
         [0024]    The present invention seeks to provide a golf ball that would allow a golfer to repeatedly practice the golfer&#39;s golf swing in a small area without having to collect a large number of balls after the practice is complete. The present invention accomplishes this by providing a short-range golf ball comprising: (1) a substantially spherical and substantially biodegradable outer shell having an interior cavity, and (2) a substantially biodegradable force-absorbing member disposed within the interior cavity. This force-absorbing member is operational to affect the performance characteristics of the golf ball so that the maximum range of the golf ball is less than 75 yards. In various embodiments of the invention, the maximum range of the golf ball is less than 50 yards, less than 25 yards, and less than 15 yards, respectively.  
           [0025]    In this embodiment of the invention, the force-absorbing member is preferably operational to at least partially absorb a force exerted on the golf ball by a golf club as the golf ball is struck by the golf club, and the golf ball is preferably disposable and entirely biodegradable. Furthermore, the golf ball is preferably configured to begin dissolving upon contact with water.  
           [0026]    In a further embodiment of the invention, the golf ball comprises: (1) a substantially spherical outer shell that defines an interior cavity and that has an outer diameter that is greater than about 1.40 inches and less than about 1.80 inches, and (2) a low-density core material disposed within the interior cavity. In this embodiment of the invention, the combined weight of the outer shell and the core material is less than about 25% of a weight of a standard golf ball.  
           [0027]    A golf ball according to this embodiment of the invention is preferably biodegradable, and the core material preferably substantially fills the cavity. Furthermore, the core material preferably comprises a foam portion. In addition, the combined weight of the outer shell and the core material is preferably less than 10 grams, and the core material preferably comprises a vegetable starch (such as corn or potato starch), or a grain starch (such as wheat starch). In a preferred embodiment of the invention, the outer diameter of the golf ball&#39;s outer shell is about 1.68 inches.  
           [0028]    In yet another embodiment of the invention, the golf ball comprises: (1) a substantially spherical outer shell that defines an interior cavity, and (2) a malleable core disposed within the interior cavity. In this embodiment of the invention, the golf ball is configured so that, in response to the golf ball being struck by a golf club, the malleable core permanently deforms, and thereby at least partially absorbs a force exerted on the golf ball by the golf club as the golf club strikes the golf ball. In this embodiment of the invention, the outer shell is preferably also malleable and configured so that, in response to the golf ball being struck by a golf club, the malleable outer shell permanently deforms, and thereby also at least partially absorbs a force exerted on the golf ball by the golf club.  
           [0029]    In this embodiment of the invention, the malleable core material is preferably operational to affect one or more performance characteristics of the golf ball so that a maximum range of the golf ball is less than 25 yards. Furthermore, the outer shell and the core material both preferably comprise biodegradable material, and the golf ball is preferably disposable.  
           [0030]    Yet another embodiment of the invention comprises a substantially uniform, substantially solid sphere comprising energy-absorbent material that is biodegradable and that is operational to affect the performance characteristics of the ball so that a maximum range of the golf ball is less than 30 yards. In this embodiment of the invention, the energy-absorbent material preferably comprises vegetable starch or wheat starch, and the golf ball is preferably disposable.  
           [0031]    A further embodiment of the invention comprises a substantially hollow sphere that is comprised at least partially of biodegradable, energy-absorbent material. In this embodiment of the invention, the biodegradable, energy-absorbent material is operational to affect the performance characteristics of the golf ball so that a maximum range of the golf ball is less than 50 yards. In this embodiment of the invention, the golf ball is preferably entirely biodegradable, and the golf ball&#39;s biodegradable, energy-absorbent material preferably defines one or more holes in an exterior portion of the substantially hollow sphere for increasing the friction between the golf ball and a gaseous medium when the golf ball is traveling through the gaseous medium.  
           [0032]    In this embodiment of the invention, the biodegradable, energy-absorbent material preferably comprises vegetable starch, the outer diameter of the outer shell is preferably about 1.68 inches, and the golf ball preferably weighs less than or equal to 10 grams. In addition, the golf ball is preferably disposable.  
           [0033]    In yet another embodiment of the invention, the golf ball comprises: (1) a substantially spherical and substantially biodegradable outer shell that defines an interior cavity; (2) liquid disposed within the interior cavity; and (3) a liquid-impermeable barrier disposed between the biodegradable outer shell and the liquid so that, before the golf ball is struck for a first time with a golf club, the liquid-impermeable barrier separates the liquid from the biodegradable outer shell. In this embodiment of the invention, the liquid-impermeable barrier is preferably configured so that after the golf ball is struck for a first time with a golf club, the liquid is no longer separated from the biodegradable outer shell.  
           [0034]    In this embodiment of the invention, the biodegradable outer shell is preferably water-soluble, and the liquid is preferably water. Furthermore, the barrier is preferably configured to tear or shatter in response to the golf ball being struck for a first time by a golf club.  
           [0035]    In an additional embodiment of the invention, the golf ball comprises: (1) a substantially-spherical central body portion that has an exterior surface and that is configured for being supported by a top surface of a golf tee; and (2) a fastener disposed on the exterior surface of the golf ball, the fastener being configured for attaching the golf ball to the top surface of the golf tee and for releasing from the top surface of the golf tee in response to the golf ball being hit by a golf club. In this embodiment of the invention, the fastener preferably comprises: (1) a piece of film having a top surface and a bottom surface; (2) a first layer of adhesive disposed on the top surface of the film; and (3) a second layer of adhesive disposed on the bottom surface of the film.  
           [0036]    In this embodiment of the invention, the golf ball may alternatively be configured for use with a golf tee having a ball-supporting top surface and defining a peg receptacle, the peg receptacle being open to the ball-supporting top surface. In this embodiment of the invention, the golf ball preferably comprises a peg that is configured for insertion into the peg receptacle. Also, the peg is preferably configured for attaching the golf ball to the top surface of the golf tee and for releasing from the top surface of the golf tee in response to the golf ball being hit by a golf club.  
           [0037]    A further embodiment of the invention comprises a method of practicing a golf swing, the method comprising the steps of: (1) providing a biodegradable golf ball, the golf ball having a maximum range of less than 50 yards; (2) hitting the golf ball a first time with a golf club; (3) before hitting the golf ball a second time with a golf club, allowing the golf ball to biodegrade. In this embodiment of the invention, the outer diameter of the golf ball is preferably about 1.68 inches, and the golf ball preferably weighs less than about 10 grams. Furthermore, the maximum range of the golf ball is preferably less than 20 yards, and the golf ball preferably comprises vegetable starch.  
           [0038]    A further embodiment of the invention comprises a method of marketing a golf ball, the method comprising the steps of: (1) communicating to a customer that the golf ball has a maximum range of 50 yards or less; (2) communicating to the customer that the golf ball is biodegradable; and (3) offering to sell the golf ball to the customer. This embodiment of the invention preferably also includes one or more of the following additional steps: (1) communicating to the customer that the golf ball is configured for only one use; and (2) communicating to the customer that the golf ball is configured for driving practice in areas other than a driving range. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]    [0039]FIG. 1A is a front view of a solid golf ball according to an embodiment of the present invention.  
         [0040]    [0040]FIG. 1B is a sectional view of the interior of the golf ball of FIG. 1A taken substantially along Line  1 - 1  of FIG. 1A in the direction indicated by the arrows of Line  1 - 1 .  
         [0041]    [0041]FIG. 2A is a front view of a layered golf ball according to an embodiment of the present invention.  
         [0042]    [0042]FIG. 2B is a sectional view of the interior of the golf ball of FIG. 2A taken substantially along Line  2 - 2  of FIG. 2A in the direction indicated by the arrows of Line  2 - 2 .  
         [0043]    [0043]FIG. 3A is a front view of a golf ball according to an embodiment of the present invention having an outer shell and an inner core.  
         [0044]    [0044]FIG. 3B is a sectional view of the interior of the golf ball of FIG. 3A taken substantially along Line  3 - 3  of FIG. 3A in the direction indicated by the arrows of Line  3 - 3 .  
         [0045]    [0045]FIG. 4A is a front view of a golf ball according to an embodiment of the present invention that comprises a liquid-soluble outer shell, a water core, and a liquid-impermeable membrane disposed between the outer shell and the liquid core.  
         [0046]    [0046]FIG. 4B is a sectional view of the interior of the golf ball of FIG. 4A taken substantially along Line  4 - 4  of FIG. 4A in the direction indicated by the arrows of Line  4 - 4 .  
         [0047]    [0047]FIG. 5A is a front view of a golf ball according to an embodiment of the present invention that comprises a hollow outer shell.  
         [0048]    [0048]FIG. 5B is a sectional view of the interior of the golf ball of FIG. 5A taken substantially along Line  5 - 5  of FIG. 5A in the direction indicated by the arrows of Line  5 - 5 .  
         [0049]    [0049]FIG. 6 is a front view of a golf ball according to an embodiment of the present invention that includes a fastener for releasably attaching the golf ball to the top surface of a golf tee.  
         [0050]    [0050]FIG. 7 is a front view of a golf ball according to an embodiment of the present invention that includes a peg for releasably attaching the golf ball to the top surface of a golf tee. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0051]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which several preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.  
       General Description of the Golf Ball  
       [0052]    A golf ball according to an embodiment of the present invention is preferably the same size and shape as a standard golf ball, but is configured to travel a significantly shorter distance than a standard golf ball. More particularly, the outer diameter of the golf ball is preferably greater than 1.40 inches and less than 1.80 inches. In a preferred embodiment of the invention, the outer diameter of the golf ball is 1.68 inches.  
         [0053]    Although the weight of a golf ball according to the present invention may be more than, less than, or the same as that of a standard golf ball (standard golf balls typically weigh approximately 45 grams), a golf ball according the present invention preferably weighs less than 25% of the weight of a standard golf ball. In a preferred embodiment of the invention, the golf ball weighs less than 10 grams.  
         [0054]    As noted above, the maximum range of a golf ball according to the invention is significantly shorter than the maximum range of a standard golf ball. More particularly, the maximum range of a golf ball according to an embodiment of the invention is preferably less than 100 yards. In a further embodiment of the invention, the maximum range of the golf ball is less than 75 yards. In yet another embodiment of the invention, the maximum range of the golf ball is less than 50 yards. In a further embodiment of the invention, the maximum range of the golf ball is less than 25 yards. In yet another embodiment of the invention, the maximum range of the golf ball is less than 15 yards.  
         [0055]    Preferably, at least a portion of the golf ball is biodegradable (i.e., capable of decomposing by natural biological processes). In a preferred embodiment of the invention, the entire golf ball is biodegradable. Preferably, part or all of the golf ball is configured to decompose quickly upon exposure to water, sunlight, or air. For example, in one embodiment of the invention, the golf ball is configured to completely dissolve after being exposed to air, water, or sunlight (or any combination thereof) for a period of time that is three days or less. After reading the description below, one skilled in the art will understand that a golf ball according to the present invention may be designed to have one of many different alternative sets of biodegradable properties. For example, the golf ball may be designed so that it completely dissolves after being exposed to both water and sunlight for a period of time that is three days or less.  
         [0056]    A golf ball according to a preferred embodiment of the invention is also preferably disposable (i.e., configured to be used as a practice golf ball only one time). For example, as is discussed in more detail below, the golf ball may be configured so that: (1) the shell of the golf ball permanently deforms in response to being struck with a golf club; (2) the core of the golf ball permanently deforms in response to being struck with a golf club; or (3) the golf ball includes a water soluble shell and a water core that are initially separated, but that are brought into contact when the ball is struck, causing the ball to quickly decompose.  
       Construction of the Golf Ball  
       [0057]    A short-range golf ball according to the present invention may be constructed in many different ways. For example, the golf ball may be constructed as a solid ball, a layered-ball, an outer shell with an inert inner core, an outer shell with a reactive inner core, or a hollow shell. Each of these exemplary embodiments is discussed in more detail below.  
       Solid Ball Construction  
       [0058]    A golf ball  10  according to a first embodiment of the invention is shown in FIGS. 1A and 1B. As may be understood from these figures, this golf ball  10  is a solid ball that comprises or consists of a single material or a single mixture of materials. This material is preferably selected to partially absorb a force exerted on the golf ball  10  when the golf ball  10  is hit by a golf club, and thereby reduce the range of the golf ball  10 . In a preferred embodiment of the invention, the golf ball  10  is made from one or more of the following materials: (1) biodegradable resin; (2) gelatin; (3) polyester; (4) cellulose; (5) modified cellulose; (6) starch; (7) modified starch; (8) gelatin; (9) Casein; or (10) biodegradable plastic. In a preferred embodiment of the invention, the golf ball is made of vegetable starch (such as corn or potato starch), or grain starch (such as wheat starch).  
         [0059]    In a further embodiment of the invention, the golf ball is comprised of one or more of the materials listed above, and also includes filler particles dispersed (either evenly or unevenly) throughout the golf ball  10 . These filler particles are preferably biodegradable and may be, for example, peat moss, vermiculite, or fertilizer. Many other types of biodegradable materials may be used as filler particles. Such filler particles are preferably either beneficial to the environment (e.g., promote the growth of grass or inhibit the growth of weeds), or at least do not harm the environment.  
         [0060]    Just as the golf ball may be constructed using a variety of different materials, the density and form of these materials may also be varied. For example, the golf ball may be manufactured to have a relatively dense solid consistency (for example, the ball may consist of relatively dense plastic resin or gelatin). Alternatively, the ball may be manufactured to have a relatively low-density consistency. For example, the ball may consist of a foam material such as a foam resin or starch. In a preferred embodiment of the invention, the golf ball is made of a vegetable starch foam, such corn starch foam.  
         [0061]    Using a less-dense material is advantageous for two reasons. First, using a less-dense material within a standard-size golf ball reduces the weight of the ball. This, in turn, generally reduces the maximum range of the golf ball. In addition, generally speaking, the less dense the ball material is, the faster it will decompose. This is because, generally speaking, the less dense a material is, the less total material needs to be broken down before the material fully decomposes. Thus, in a preferred embodiment of the invention, a material is selected so that the total weight the golf ball (which is preferably approximately 1.68 inches in diameter) is less than 10 grams.  
         [0062]    While the density of a solid-construction golf ball according to one embodiment of the present invention is uniform throughout the golf ball, it should be understood that, in alternative embodiments of the invention, different parts of the golf ball may have different densities. For example, in a preferred embodiment of the invention, the golf ball comprises or consists of a single type of foam that is relatively dense at the exterior portions of the ball, and that is less dense in the interior portions of the ball. This configuration is advantageous because it provides the ball with a relatively hard exterior surface (which may preferably be similar to the hard exterior surface of a standard golf ball), and a relatively soft, low-density interior material. The soft, low-density characteristics of the interior material serve to reduce the overall weight of the ball and to cause the material to be more prone to contract or deform (and therefore absorb energy) when the ball is struck with a golf club. Both of these features of this embodiment are advantageous because they serve to reduce the maximum range of the golf ball.  
         [0063]    The maximum range of the golf ball may also be reduced by providing dimples or holes in the exterior portion of the golf ball. For example, the golf ball may define a series of holes that are dispersed uniformly over the exterior surface of the golf ball. These holes serve to increase the friction between the golf ball and a gaseous medium (such as air) when the golf ball is traveling through the gaseous medium. This, in turn, generally reduces the maximum range of the golf ball.  
       Layered Construction  
       [0064]    A golf ball  20  according to a second embodiment of the invention is shown in FIGS. 2A and 2B. As may be understood from these figures, the golf ball  20  includes a plurality of distinct layers of material. More specifically, the golf ball  20  shown in FIGS. 2A and 2B has three distinct layers of material  24 ,  26 ,  28 . These layers include a substantially spherical inner core layer  28 , a substantially spherical middle layer  26  surrounding the inner core layer  28 , and a substantially spherical outer layer  24  surrounding the middle layer  26 . The inner core layer  28  and the middle layer  26  are preferably dimensioned so that the outer portion of the inner core layer  28  engages the inner portion of the middle layer  26 . Similarly, middle layer  26  and the outer layer  24  are preferably dimensioned so that the outer portion of the middle layer  26  engages the inner portion of the outer layer  24 . In one embodiment of the invention, the various layers  24 ,  26 ,  28  are attached together using an adhesive substance, such as glue.  
         [0065]    While the golf ball  20  of FIGS. 2A and 2B show three distinct layers, a layered golf ball according to the present invention may include more or less than three layers. For example, the golf ball may include 2, 3, 4, 5, 6, 7, 8, 9, or more individual layers of material.  
         [0066]    Each of the various layers of the golf ball  20  is preferably comprised of a single material, or a single mixture of materials. Each of these materials is preferably selected to partially absorb a force exerted on the golf ball  20  when the golf ball  20  is hit by a golf club, and to thereby reduce the range of the golf ball  20 . (Thus, because, in a preferred embodiment of the invention, the various layers of the golf ball  20  are designed to absorb a force exerted on the golf ball  20  when the golf ball  20  is hit with a golf club, the layers may be referred to as force absorbing members.) In addition, the outermost layer  24  of the golf ball  20  is preferably more dense (and harder) than the golf ball&#39;s various inner layers. This gives the golf ball  20  exterior characteristics that are similar to those of a standard golf ball.  
         [0067]    In a preferred embodiment of the invention, each layer of the golf ball  20  is made from one or more of the following materials: (1) a biodegradable resin; (2) gelatin; (3) a polyester; (4) cellulose; (5) modified cellulose; (6) a starch; (7) a modified starches; (8) gelatins; (9) casein; or (10) a biodegradable plastic. In a preferred embodiment of the invention, at least one of the golf ball&#39;s inner layers  28 ,  26  is made of vegetable starch (such as corn or potato starch), or grain starch (such as wheat starch).  
         [0068]    In a further embodiment of the invention, at least one of the golf ball&#39;s various layers  24 ,  26 ,  28  is comprised of one or more of the materials listed above, and also includes filler particles dispersed (either uniformly or non-uniformly) throughout the layer. These filler particles are preferably biodegradable and may be, for example, peat moss, vermiculite, or fertilizer. Many other types of biodegradable materials may be used as filler particles. However, such filler particles are preferably either beneficial to the environment (e.g., promote the growth of grass, or inhibit the growth of weeds), or at least do not harm the environment.  
         [0069]    Just as the golf ball&#39;s various layers may be constructed using a variety of different materials, the density and form of these layers may also be varied. For example, one or more of the golf ball&#39;s various layers may be manufactured to have a relatively dense solid consistency (for example, one or more layers may consist of relatively dense plastic resin or gelatin). Similarly, the golf ball&#39;s various layers may be manufactured to have a relatively low-density consistency. For example, one or more of the golf ball&#39;s layers may include a foam material such as a foam resin or starch. In a preferred embodiment of the invention, the ball is made of a vegetable starch foam, such a corn starch foam. In a further preferred embodiment of the invention, the golf ball&#39;s various layers are designed so that the total weight the golf ball (which is preferably approximately 1.68 inches in diameter) is less than 10 grams.  
         [0070]    Like the density of a solid construction golf ball, the various layers of a layered construction golf ball may either have a uniform density or a non-uniform density. For example, in a preferred embodiment of the invention, the outermost layer  24  of the golf ball  20  comprises a single type of foam that is relatively dense at the exterior portions of the layer  24 , and that is less dense in the interior portions of the layer  24 . This configuration is advantageous because it provides the ball with a relatively hard exterior surface (which is preferably similar to the exterior surface of a golf ball), and a relatively soft, low-density interior portion of the exterior layer. The soft, low-density characteristics of the interior portion of the outer layer  24  of material serve to reduce the overall weight of the golf ball  20  and to cause the outer layer  24  to be more prone to contract or deform (and therefore absorb energy) when the golf ball  20  is struck with a golf club. Both of these features are advantageous because they generally serve to reduce the maximum range of the golf ball  20 .  
         [0071]    In a preferred embodiment of the invention (referred to as the “Outer Shell with Inner Core Embodiment”) shown in FIGS. 3A and 3 b,  the golf ball  30  includes two layers—an interior core layer  36 , and an exterior shell layer  34 . As may be understood from FIG. 3B, the exterior shell layer  34  is a relatively thin, substantially spherical layer that defines an inner cavity  35 , and the interior core layer  36  is disposed within this inner cavity  35 . To make the golf ball&#39;s exterior surface similar to a standard golf ball, the exterior shell layer  34  is preferably relatively hard and dense. More particularly, in a preferred embodiment of the invention, this exterior shell layer  34  is made up of a relatively dense, biodegradable resin.  
         [0072]    As noted above, the exterior shell layer  34  is preferably hard and relatively thin. This is advantageous because it provides the golf ball  30  with a hard outer layer that is similar to a standard golf ball, while minimizing the amount of dense material within the ball. This, in turn, reduces the weight of the golf ball (which generally minimizes the golf ball&#39;s maximum range) and generally causes the golf ball to biodegrade faster than it would if it were made entirely of dense material.  
         [0073]    In addition to being thin, the exterior shell  34  may be dimpled or otherwise shaped to affect the flight characteristics of the golf ball  30 . For example, in one embodiment of the invention, the golf ball&#39;s exterior shell layer  34  defines a series of holes (such as the holes  52  of the embodiment of the invention shown in FIG. 5) that are dispersed uniformly throughout the golf ball&#39;s exterior shell layer  34 . These holes serve to increase the friction between the golf ball  30  and a gaseous medium (such as air) when the golf ball  30  is traveling through the gaseous medium. This, in turn, generally reduces the maximum range of the golf ball  30 .  
         [0074]    In a preferred embodiment of the invention, the exterior shell layer  34  of the golf ball  30  is malleable and is configured to permanently deform upon being hit with a golf club. This causes the exterior shell layer  34  to at least partially absorb a force exerted on the golf ball  30  when the golf ball  30  is struck by a golf club. This advantageously generally reduces the distance that the golf ball  30  will travel in response to being hit by a golf club.  
         [0075]    Similarly, in a particular embodiment of the invention (an example of which is shown in FIG. 3), the golf ball&#39;s interior core layer  36  is malleable and is also configured to permanently deform in response to the golf ball being hit by a golf club. This causes the inner core layer  36  to at least partially absorb a force exerted on the golf ball  30  when the golf ball  30  is struck by a golf club. This advantageously reduces the distance that the golf ball  30  will travel in response to being hit by a golf club.  
         [0076]    In one embodiment of the invention, the exterior shell layer  34  is malleable and is configured to permanently deform in response to the golf ball  30  being hit by a golf club, and the interior core layer  36  is not. In another embodiment of the invention, the interior core layer  36  is malleable and is configured to permanently deform in response to the golf ball  30  being hit by a golf club, and the exterior shell layer  34  is not. In a further embodiment of the invention, both the interior core layer  36  and the exterior shell layer  34  are malleable and are configured to permanently deform in response to the golf ball  30  being hit by a golf club.  
         [0077]    Preferably, a golf ball according to the “outer shell with inner core” embodiment of the invention is constructed so that the outer surface of the interior core layer  36  engages the inner surface of the exterior shell layer  34 , and so that neither the exterior shell layer  34  nor the interior core layer  36  decompose in response to being in contact with each other. Alternatively, in an embodiment of the golf ball such as the embodiment shown in FIGS. 4A and 4B, the exterior shell layer  44  and the interior core layer  46  may be comprised of materials that are selected so that either the exterior shell layer  44  or the interior core layer  46  (or both the exterior shell layer  44  and the interior core layer  46 ) dissolve in response to the interior core layer  46  and the exterior shell layer  44  coming into contact with one another. In this embodiment of the invention, the exterior shell layer  44  and the interior core layer  46  are initially separated by a preferably spherical membrane  45  that is preferably impermeable to either: (1) the material of which the shell layer  44  is comprised; (2) the material of which the core layer  46  is comprised; or (3) both the material of which the shell layer  44  is comprised, and the material of which the core layer  46  is comprised. The membrane  45  is preferably configured so that, in response to the golf ball being struck for a first time with a golf club, the core layer  46  (which may be, for example, a solid, a liquid, a gel, a powder, or a reactive gas) is no longer separated from the shell layer  44 . As a result, either the shell layer  44 , the core layer  46 , or both the shell layer  44  and the core layer  46  begin to decompose in response to the golf ball  40  being struck with a golf club. In a preferred embodiment of the invention, the membrane  45  is configured to tear or fracture in response to the golf ball  40  being struck by a golf club.  
         [0078]    For example, a golf ball  40  according to a preferred embodiment of the invention includes a water-soluble shell layer  44  and has a core layer  46  that comprises water. The water core layer  44  is initially separated from the shell layer  44  by a water-impermeable membrane  45  that is configured to shatter or tear when the golf ball  40  is struck with a golf club. Thus, when the golf ball  40  is struck with a golf club, the water-impermeable membrane  45  tears or shatters and, thus, allows water from the ball&#39;s interior core layer  46  to come into contact with the water-soluble exterior shell layer  44 . As a result, the exterior shell layer  44  immediately begins to decompose in response to the golf ball  45  being hit with a golf club.  
         [0079]    In an additional embodiment of the invention, an example of which is shown in FIGS. 5A and 5B, the golf ball  50  comprises a single, hollow, spherical shell layer  54  that defines an interior cavity  56 . This shell layer  54  is preferably relatively thin, hard, and entirely biodegradable. The exterior surface  55  of the shell layer  54  may be dimpled, or contain holes that extend either partially or entirely through the shell layer  54  and that serve to alter the aerodynamic properties of the golf ball  50 . For example, in the embodiment of the invention shown in FIG. 6, the outer shell layer  54  of the golf ball  50  defines a plurality of holes  52  that are positioned relatively uniformly over the surface of the golf ball  50 .  
       Fabrication Techniques  
       [0080]    As will be understood by one skilled in the relevant art, golf balls according to the various embodiments of the present invention described above may be fabricated using a variety of manufacturing techniques, such as foam injection molding and reactive injection molding. For example, a solid golf ball according to the present invention could be made by injecting a biodegradable material into a desired mold to form a solid golf ball.  
         [0081]    As will be understood by one skilled in the art, when the golf ball is comprised of a foam resin, the density of the foam may be varied by changing the amount of air mixed into the resin during fabrication. That is, the foam density is dependent upon the resin-to-air ratio used during mixing and injection. This density can be varied to manipulate the final decomposition rate of the golf ball. Generally speaking, the higher the resin-to-air ratio of a particular foam, the greater the density of the foam will be, and the slower the foam will biodegrade. Similarly, the lower the resin-to-air ratio for a particular foam, the more quickly the foam will biodegrade.  
         [0082]    The density of a golf ball comprised of a resin foam may also be varied (as described above) to determine the final weight and hardness of the golf ball. Generally speaking, the greater the resin-to-air ratio of a particular foam, the greater the weight and hardness of the golf ball will be, and the farther the ball will travel when hit. If the resin-to-air ratio is lowered, the foam will be less dense, and the ball will be lighter and softer and will generally travel a shorter distance when hit.  
       Color of the Golf Ball  
       [0083]    A golf ball according to the present invention may be manufactured to have an exterior color that provides the golf ball with particular advantageous visual properties. This may be accomplished, for example, by manufacturing the golf ball with exterior materials of a desired color, or by dying or painting the exterior of the ball the desired color. In a preferred embodiment of the invention, the golf ball is painted green so that the ball is difficult to see when hit into a grassy area. Additional embodiments of the ball are, respectively, orange (for making the ball easy to see when hit onto grass, snow or mud), and snow white (for allowing the ball to blend into snow when hit into a snowy area). The golf ball may be manufactured of other colors to provide other additional advantageous features.  
       Golf Ball with Fastener  
       [0084]    Because a golf ball according to the present invention will typically be much lighter than a standard golf ball, these golf balls may have the tendency to be blown off of a golf tee by slight gusts of wind or by air currents caused by the movements of a golfer or a golf club. In addition, some embodiments of the golf ball may be constructed to lower physical tolerances than a standard golf ball and the resulting (possibly uneven) surface curvature and features of the golf ball could cause the ball to sit unevenly on a golf tee. Such instability may cause golf balls according to the present invention to easily fall off the tee.  
         [0085]    Accordingly, in one embodiment of the invention shown in FIG. 6, the golf ball  60  is provided with a preferably biodegradable fastener  64  that is disposed on, and attached to, an exterior surface of the golf ball  60 . This fastener  64  is configured to hold the golf ball  60  on the tee  66  before the golf ball  60  is hit by a golf club and to quickly release from the golf tee  66  when the golf ball  60  is hit by the golf club. In this way, the fastener  64  holds the golf ball  60  on the tee  66  before the golf ball  60  is hit and also prevents the tee  66  from interfering with the flight of the golf ball  60  after the golfer hits the golf ball  60 .  
         [0086]    In a preferred embodiment of the invention, the fastener  64  is in the form of a circle and has a diameter that is approximately the same as a diameter of the top of a standard golf tee. In this preferred embodiment of the invention, the fastener  64  is a thin peace of adhesive film having adhesive on both a top surface and a bottom surface of the film. A first surface of this adhesive film is preferably attached to the exterior of the golf ball  60  during the manufacturing process, and an opposite second adhesive surface of the adhesive film is covered with a protective layer that covers the second adhesive surface of the film until the golf ball  60  is to be used. To use the golf ball  60 , a golfer removes the protective layer to expose the second adhesive surface of the adhesive film, places the golf ball  60  on a golf tee  66  so that the exposed adhesive surface of the adhesive film sticks to the top surface of the golf tee, and hits the ball  60 . In a preferred embodiment of the invention, the adhesive film is biodegradable.  
         [0087]    In alternative embodiments of the invention, the fastener may be, for example: (1) water-soluble glue; (2) gelatin foam with adhesive on both sides; (3) a gelatin matrix with adhesive dispensed throughout the gelatin matrix; (4) adhesive putty; or (5) adhesive gel. In one embodiment of the invention, the fasteners are packaged separately from the golf ball (in, for example, rolls, sheets, bottles, or cans) and are configured to be manually attached to the ball by a golfer.  
         [0088]    In a further preferred embodiment of the invention, the fastener is an elongate peg  72  that protrudes from the exterior surface of the golf ball  70  as shown in FIG. 7. This elongate peg  72  is preferably positioned to extend along a line that extends through the center of the golf ball  70 . As is shown in FIG. 7, this golf ball  70  is configured for use with a modified golf tee  76  that is preferably the same general size and shape of a standard golf tee, but that includes a peg receptacle  74  that is open to the ball-supporting top surface  75  of the golf tee  76  to receive the elongate peg  72  prior to use. The tee  76  is preferably dimensioned so that the peg receptacle  74  is open to the top surface of the tee  76  near the center of the tee&#39;s top surface  75 . The peg receptacle  74  is preferably approximately the same size and shape as the exterior surface of the elongate peg  72 .  
         [0089]    To use this preferred embodiment of the invention, the user places the golf ball  70  on the tee  76  so that the peg  72  extends into the peg receptacle  74  and is held in place within peg receptacle  74  by the friction between the peg  72  and the portion of the golf tee  76  that defines the peg receptacle  74 . This tends to hold the golf ball  70  in place on the golf tee  76  until the golfer hits the golf ball  70 . The peg  72  preferably becomes dislodged from the peg receptacle  74  when the golf ball  70  is struck with a golf club. In a preferred embodiment of the invention, the peg  72  is made of a biodegradable material, such as wood.  
       Method of Marketing the Golf Ball  
       [0090]    The present invention also includes a unique method of marketing a golf ball. This method of marketing includes the steps of: (1) communicating to a customer that the golf ball has a maximum range of 50 yards or less; (2) communicating to the customer that the golf ball is biodegradable; and (3) offering to sell the golf ball to the customer. This method preferably includes the additional steps of communicating to the customer that the golf ball is configured for only one use, and communicating to the customer that the golf ball is configured for driving practice in areas other than a driving range.  
       Conclusion  
       [0091]    Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. For example, the concepts above could be applied to other types of practice balls, such as practice baseballs. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.