FIELD OF THE INVENTION

This invention relates to a golf club head and a golf club incorporating the golf club head.

BACKGROUND

Golf is enjoyed by a large variety of players of differing ages and skill levels, and has experienced an increase in worldwide popularity in recent years. As a result of the rapid uptake of golf as a recreational activity, manufacturers of golf equipment have developed various modifications to the equipment in an attempt to make the game of golf easier to play and/or to allow the golfer to improve their game.

Much of this development has focused on the club head, and has primarily focused on the size/volume of the club head. Golf club heads are designed to launch a golf ball as far as possible within the USGA Rules of Golf, when properly struck. In general, club head volume has increased over time and this has resulted in greater achievable golf ball travel distances. For example, in the case of the driver (the Ί wood'), the internal volume of the club-head has nearly doubled since 1995, when the maximum size was 250 cubic centimetres in internal volume. It was presumed that the larger driver would have a higher moment of inertia, making it easier to hit the ball straight, even if the point of impact was off-centre. In 2004, the USGA imposed a 460 cubic centimetre limit on club head size.

The optimal point of contact between a golf club and ball is frequently described as the 'sweet spot'. The sweet spot is struck when the centre of gravity (COG) of the club head is moving directly towards the centre of gravity (COG) of the golf ball at the point of impact. Striking the sweet spot provides optimal energy transfer from the club head to the ball. A ball struck accurately at the sweet spot will travel straight, providing the maximum distance the swing will allow. Similarly, when a golfer is seeking to send a ball to the left or right ('fade' or 'draw') by altering the path of the club head relative to the club face angle, maximum distance and control can be achieved by striking the ball with the sweet spot.

Even the greatest of professional golfers do not strike each and every shot perfectly. For the vast majority of golfers, perfectly struck golf shots are an exception if not a rarity. It has been estimated that PGA tour-professional golfers 'miss' the sweet spot between 15- 20% of the time, during tour events, frequently 'saving' their shot through the sheer distance they can achieve. It is, therefore, a reasonable assumption to suggest that the likelihood of a recreational golfer missing the sweet spot is somewhat greater. If a golf ball is struck away from the sweet spot, the transfer of available energy to the ball is reduced, resulting in a loss of distance. Further away from the sweet spot, the energy transfer becomes less efficient.

It is generally accepted that if a ball is struck at a point on the club face that is even 25 mm from the sweet spot, 10% of distance will be lost. Furthermore, the club head will twist during impact, and control and direction will be compromised. This is known as the 'gear effect'.

Manufacturers regularly promote new clubs as having a 'larger sweet spot'. However, this claim is not technically accurate. In terms of simple physics, the optimal point of contact between club face and ball 'sweet spot' cannot be made 'larger'. When a ball is struck at the sweet spot, the centre of gravity (COG) of the club head is moving directly towards the centre of gravity (COG) of the golf ball. Both centres of gravity are exact points, and accordingly the 'sweet spot' is an exact point on the golf club face.

While the size of golf club heads and club faces has doubled in some cases, the size of the golf ball is strictly regulated and has remained constant. The effects of a miss-hit (a hit where the club face does not impact the ball at the sweet spot) are exacerbated by the sheer size differential between club and ball.

A variety of innovations have accompanied the rapid development of golf club heads to attempt to compensate for the effects of a miss-hit. The use of polymer

inserts/mouldings has been at the forefront of these developments. Shock-absorbent inserts offer a degree of control over a miss-hit.

The objective of the addition of shock-absorbent material within the context of contemporary club design is twofold. In the first instance, this material absorbs the wrench and shock force caused by hitting, enabling a golfer to acquire stability of ball control, particularly at the grip end of the golf club. Secondly, the use of shock-absorbent inserts focusses on absorbing the effects of a miss-hit, or an off-centre hit at the point of impact between ball and club face. These inserts are usually part of the club face, often filling a 'cut-out', to absorb and dissipate energy, when a miss-hit occurs.

A golf club head having a polymer insert within the club face can provide a more efficient impact between a golf ball and the golf club head. By utilising polymer with desired material properties of stress, strain and damping levels, the face section may incur higher strain and strain rate levels than the golf ball. The lower internal stresses within the golf ball yield a more efficient impact with a golf club head. The measurement of the efficiency of a collision between two objects is known as the Coefficient of Restitution, COR, or 'trampoline effect'. The COR is the ratio of the velocity of separation to the velocity of approach. With the rapid development of construction materials, particularly titanium, the club face has become significantly lighter, stronger and thinner, enabling the exploitation of the 'trampoline effect'.

However, the USGA has specified a limit to the efficiency of the impact between a golf club head and a golf ball. The USGA has specified a maximum COR of 83% for conforming golf club heads.

All golf club manufacturers seek, for marketing reasons, a point of difference. In the case of the club head, while overall size has now been limited, technological development continues with rapidity. An increasing selection of manufacturing materials has become available. These materials include titanium, tungsten, scandium, composite alloys, carbon-fibre and polycarbonates. Titanium remains the preferred component of choice for the production of club heads, due to its lightness and strength.

Additional developments to the club head include: the addition of adjustable, recessed weights on the outer body of the club-head; the shaving of parts of the club face; an offset of the club tail to the triangulated point of-contact; cosmetic modifications; and ball control adjustment, via altering the angle of contact through a mechanism where the club head is adjoined to the club shaft.

In the golf industry, club design takes into consideration many factors, including weight, weight distribution, spin rate, coefficient of restitution, characteristic time, volume, face area, sound, materials, construction techniques, durability, and many other

considerations.

As a result, club designers are faced with performance trade-offs, between design features that enhance one aspect of club performance while reducing at least another aspect of club performance.

For example, lighter weight can often lead to faster club speed, which often leads to greater distance; however, clubs that are too light can become uncontrollable for the user. In another example, thinner club faces often lead to distance gains, but thinning faces reduces durability in manufacture.

It is an object of at least preferred embodiments of the present invention to provide a golf club head that addresses at least some of the problems associated with known golf club heads, and/or to at least provide the public with a useful alternative. SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, there is provided a golf club head comprising : a body having a club face for contacting a ball, and a rear portion

substantially opposite the club face; and a force-transfer member within the body, the force-transfer member having a first end at or adjacent the club face, and a second end in communication with the rear portion of the body, the force-transfer member arranged to transfer force from the club face to the rear portion of the body when the club face strikes a ball.

In an embodiment, the force-transfer member comprises an elongate portion extending between the first end of the force-transfer member and the second end of the force- transfer member. In an embodiment, a portion of the body surrounding the elongate portion of the force-transfer member is substantially hollow.

In an embodiment, an axis of the golf club head passes from an optimal point of impact of the club face and through a centre of gravity of the golf club head, and the elongate portion of the force-transfer member is substantially coaxial with the axis. In an embodiment, the axis of the golf club head passes through the rear portion of the golf club head. In an embodiment, the optimal point of impact is located substantially at a centre of the club face.

In an embodiment, the elongate portion of the force-transfer member extends at an angle of about 90° from the club face in a vertical plane. In an alternative embodiment, the elongate portion of the force-transfer member extends at an angle of less than 90° from the club face in a vertical plane.

In an embodiment, the elongate portion of the force-transfer member extends at an angle of about 90° from the club face in a horizontal plane. In an alternative

embodiment, the elongate portion of the force-transfer member extends at an angle of less than 90° from the club face in a horizontal plane.

In an embodiment, the first end of the force-transfer member comprises a tapered portion, the tapered portion tapering outwardly toward the club face. In an embodiment, an outer part of the taper is substantially the same size and shape as the club face.

In an embodiment, the second end of the force-transfer member comprises a plate arranged to transfer force to the rear portion of the body. In an embodiment, the plate is shaped to substantially match a curvature of an inner surface of the rear portion of the body. In an embodiment, the force-transfer member passes through a centre of gravity of the golf club head.

In an embodiment, the golf club head further comprises a shock-absorbent member located between the second end of the force-transfer member and the rear portion of the body.

In an embodiment, the force-transfer member is integrally formed with the club face.

In an embodiment, the force-transfer member further comprises a weighted portion. In an embodiment, the weighted portion is arranged to lower a centre of gravity of the golf club head. In an embodiment, the weighted portion is integrally formed with the tapered portion of the force-transfer member.

In an embodiment, the force-transfer member is formed from titanium.

In an embodiment, the golf club head comprises a removable adjustment component.

In an embodiment, the removable adjustment component is arranged to transfer force from the second end of the force transfer member to the rear portion of the body when the club face strikes a ball.

In an embodiment, the removable adjustment component comprises a shock-absorbent member having a first property.

In an embodiment, the removable adjustment component is removable from the golf club head and is replaceable with an alternative removable adjustment component that comprises a shock-absorbent member having a second property that differs from the first property.

In an embodiment, the first property and second property comprise stiffness, to enable adjustment of the Coefficient of Restitution of the golf club head.

In an embodiment, the removable adjustment component comprises a sleeve, and the second end of the force transfer member is telescopically received in the sleeve when the removable adjustment component is engaged with the golf club head.

In accordance with a second aspect of the invention, there is provided a golf club comprising a shaft connected to the golf club head as outlined above in relation to the first aspect. In an embodiment, the angle of the club face relative to a longitudinal axis of the shaft defines a loft angle of the club face. In an embodiment, an angle at which the force- transfer member extends from the club face is proportional to the loft angle.

In an embodiment, the elongate portion of the force-transfer member is arranged to substantially align with a direction of movement of the golf club head when the golf club is swung by a user.

In accordance with a third aspect of the invention, there is provided combination of a golf club as outlined in above in relation to the second aspect, and a plurality of removable adjustment components to adjust the performance of the golf club head.

The removable adjustment components may have any one or more of the features outlined above.

The term 'comprising' as used in this specification and claims means 'consisting at least in part of'. When interpreting statements in this specification and claims which include the term 'comprising', other features, besides the features prefaced by this term in each statement, can also be present. Related terms such as 'comprise' and 'comprised' are to be interpreted in a similar manner.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known

equivalents are deemed to be incorporated herein as if individually set forth. As used herein the term '(s)' following a noun means the plural and/or singular form of that noun.

As used herein the term 'and/or' means 'and' or 'or', or where the context allows both.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only and with reference to the accompanying drawings in which :

Figure 1 shows a front perspective view of a golf club head having an internal force- transfer member;

Figure 2A shows a front/top exploded perspective view of the golf club head;

Figure 2B shows a rear/bottom exploded perspective view of the golf club head;

Figure 3 shows a side view of the golf club head, with the force-transfer member shown in hidden detail;

Figure 4 shows a top view of the golf club head, with the force-transfer member shown in hidden detail;

Figure 5 shows a side section view of the golf club head, taken along the vertical plane A- A as indicated in figure 1;

Figure 6 shows a top section view of the golf club head, taken along the horizontal plane B-B as indicated in figure 1;

Figure 7 shows a side section view of a first alternative embodiment of the golf club head having a club face with a loft angle, taken along the vertical plane A-A as indicated in figure 1;

Figure 8 shows a top section view of a second alternative embodiment of the golf club head having an offset rear portion, taken along the horizontal plane B-B as indicated in figure 1; Figure 9 shows a side section view of a third alternative embodiment of the golf club head having a weighted portion, taken along the vertical plane A-A as indicated in figure 1;

Figure 10 shows a rear overhead perspective view of a fourth alternative embodiment of the golf club head;

Figure 11 shows a right side sectional view of the fourth alternative embodiment golf club head;

Figure 12 shows a rear overhead perspective view of the fourth alternative embodiment golf club head, with a removable adjustment component removed from the head;

Figure 13 shows a cutaway partial sectional rear overhead perspective view of the fourth alternative embodiment golf club head, with the removable adjustment component in place in the golf club head;

Figure 14A shows a rear overhead perspective view of the removable adjustment component;

Figure 14B shows a side view of the removable adjustment component;

Figure 14C shows a rear overhead perspective sectional view of the removable adjustment component;

Figure 14D shows a side sectional view of the removable adjustment component.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows a schematic illustration of a golf club head 1. Figure 1 illustrates the general design of No's: 1, 2 3, 4, 5, 6 and 7 clubs, nominally described as 'drivers', 'woods', 'fairway woods', 'rescue woods' and 'hybrid woods'. The golf club head 1 comprises a body 5 having a front club face 10 for contacting a ball, and a rear portion 11 substantially opposite the club face 10 that may be referred to as the tail. The top 12 of the body 5 is known as the crown, and the bottom 18 of the body 5 is known as the sole. A hosel 20 extends from one side of the crown 12. The portion of the club face 10 nearest the hosel 20 is known as the heel 22. The portion of the club face 10 furthest from the hosel 20 is known as the toe 24. The hosel 20 is adapted to connect the golf club head 1 to a shaft 26 to form a golf club. An optimal point of impact 28, also known as the sweet spot, is located on the club face 10. In the embodiment shown, the optimal point of impact 28 is located at the centre of the club face 10.

The terms 'top', 'bottom', 'front', 'rear' and 'sides' as used herein are defined with reference to the typical terminology used to describe a golf club head. The 'bottom' is the surface that is closest to the ground when the golf club is in use. The 'top' is the surface that opposes the bottom. The 'front' is the surface that is used to strike a ball when the golf club is in use. The 'rear' is the surface that opposes the front. The 'sides' are the surfaces that extend between the top, bottom, front and rear.

The term 'horizontal' as used herein refers to a direction extending substantially parallel to the top and bottom of the golf club head. The term 'vertical' as used herein refers to a direction extending substantially perpendicular to the horizontal direction.

Unless otherwise specified, it should be appreciated that references to directions and orientations in the following description such as 'top', 'bottom', 'front', 'rear', 'sides', 'horizontal' and 'vertical' are for reference only, and should not be considered limiting.

Figures 2A and 2B show exploded views of the golf club head 1. The golf club head 1 has the body 5 and a force-transfer member 34 within the body 5. The body 5 has the club face 10 for contacting a ball, and the rear portion 11 substantially opposite the club face 10. The force-transfer member 34 has a first end 36 at or adjacent the club face 10, and a second end 37 in communication with the rear portion 11 of the body 5. The force- transfer member 34 is arranged to transfer force from the club face 10 to the rear portion 11 of the body 5 when the club face 10 strikes a ball.

The force-transfer member 34 comprises an elongate portion 38 extending between the first end 36 of the force-transfer member and the second end 37 of the force-transfer member 34.

The second end 37 of the force-transfer member 34 comprises a plate 37a arranged to transfer force to the rear portion of the body 5. The plate 37a is shaped to substantially match a curvature of an inner surface of the rear portion 11 of the body 5.

A shock-absorbent member 40 is located between the second end 37 of the force- transfer member 34 and the rear portion 11 of the body 5. In particular, the shock- absorbent member 40 is located between the plate 37a and the rear portion 11 of the body 5. The shock-absorbent member 40 comprises shock-absorbent material.

The outer part of the body 5 has generally the same shape as a known golf club head. In the embodiment shown, the body 5 has the shape of a 'wood' club head. Woods are the largest clubs, and are used for the longest shots. Woods typically have a metal body, with a hollow interior. The invention is equally applicable to other types of golf club heads that have hollow interiors. These are commonly referred to as woods, drivers, hybrids, fairway/ rescue woods, and hollow irons. A portion of the body 5 surrounding the elongate portion 38 of the force-transfer member 34 is substantially hollow.

The hollow portion of the body 5 may contain a shock-absorbing material, or other performance-modifying addition such as weights.

An axis C-C of the golf club head 1 passes from an optimal point of impact 28 of the club face 10 and through the centre of gravity (COG) 42 of the golf club head. The elongate portion 38 of the force-transfer member 34 is substantially coaxial with the axis C-C. The axis C-C of the golf club head 1 also passes through the rear portion 11 of the golf club head 1. In the embodiment shown, the axis C-C passes through the rearmost point 11a of the rear portion 11.

The optimal point of impact 28 is located substantially at the centre of the club face 10. The force-transfer member 34 passes through the centre of gravity 42 of the golf club head 1.

In alternative embodiments, the optimal point of impact 28 may be located elsewhere on the club face. For example, the optimal point of impact 28 may be shifted by the addition of weights to the club head (described in more detail below).

The body 5 may be manufactured from any suitable material, particularly a material that is used in the manufacture of contemporary golf clubs. An exemplary material is titanium.

The force-transfer member 34 is subject to a compressive force when the golf club head 1 strikes a golf ball.

Figure 3 shows a side view of the club head 1 of figures 2A and 2B, with the force- transfer member 34 and shock-absorbent member 40 shown in hidden detail. Figure 5 shows a corresponding section view of the club head 1 viewed along the vertical plane A- A as indicated in figure 1. Figure 5 highlights the club face 10, the force-transfer member 34, and the plate 37. Figures 3 and 5 show the elongate portion 38 of the force-transfer member 34 extending at an angle of about 90° from the club face 10 in the vertical plane.

Figure 4 shows a top view of the club head 1 of figures 2A and 2B, with the force-transfer member 34 and shock-absorbent member 40 shown in hidden detail. Figure 6 shows a corresponding section view of the club head 1 viewed along the horizontal plane B-B as indicated in figure 1. Figure 6 highlights the club face 10, the force-transfer member 34, and the plate 37. Figures 4 and 6 show the elongate portion 38 of the force-transfer member 34 extending at an angle of about 90° from the club face 10 in the horizontal plane.

The first end 36 of the force-transfer member 34 comprises a tapered portion 36a, the tapered portion 36a tapering outwardly toward the club face 10. An outer part of the taper is substantially the same size and shape as the club face 10. As shown in figures 2A-10, the tapered portion 36a tapers in both the horizontal plane and the vertical plane. The tapered portion 36a may extend to one or more of the crown 12, sole 18, heel 22, and toe 24 of the club body 5. The tapered portion 36a may extend to each of the crown 12, sole 18, heel 22, and toe 24 of the club body 5.

Referring to figures 3 and 4, the tapered portion 36a extends from the club face 10 via opposed, generally concave curves (when viewed from the side), centred around the axis C-C. The tapered portion 36a starts at or near the outer periphery of the club face 10, and narrows towards the axis C-C further away from the club face 10 up until the cross- section of the tapered portion 36a is the same as that of the elongate portion 38. At least part of the tapered portion 36a may have a circular or oval cross-section. The tapered portion 36a may have any other suitable shape that is compatible with the geometry of the club head body 5.

In the embodiment shown, the force-transfer member 34 is integrally formed with the club face 10. In alternative embodiments, the force-transfer member 34 is a separate component.

The elongate portion 38 is aligned with the optimal point of impact 28 and the centre of gravity 42 along the axis C-C. Kinetic energy is transferred through the elongate portion 38 to a golf ball via the tapered portion 36a and the club face 10 at the point of impact with the golf ball. This may advantageously provide power to the shot at the point of impact with the golf ball.

Immediately following impact between the club face 10 and ball, a reaction force from the impact is transferred through the elongate member 38 to the rear portion (tail) 11 of the club head 1 via the plate 37a and the shock-absorbent member 40. This arrangement may advantageously help absorb the 'shock' of the impact.

In the embodiment shown, the elongate portion 38 is a shaft having a circular cross- section. Alternatively, the elongate portion 38 may have any other suitable cross-section, such as an oval, square, or oblong cross-section. The plate 37a may be shaped to have a contour that is substantially the same as the contour of the interior surface of the rear portion 11 of the body 5. The force-transfer member 34 is sized such that there is a gap between the plate 37a and the interior surface of the rear portion 11 of the body 5. The gap is sized to accommodate the shock- absorbent member 40. The gap may be about 1 mm, 2 mm, 3 mm, 4 mm or 5mm wide, for example.

The plate 37a allows impact forces transmitted through the elongate portion 38 to be absorbed and dissipated, via the shock-absorbent member 40 located between the plate 37a and the internal surface of the rear portion 11 of the body 5.

The overall design of the golf club head 1 will determine the design and material composition of the force-transfer member 34. The force-transfer member 34 may have a solid construction. Alternatively, a portion of the force-transfer member 34 may be hollow, providing a manufacturer an opportunity to increase the weight (by adding lead, for example), or to introduce another material to modify the properties of the force- transfer member.

The force-transfer member 34 may be formed from any suitable material. Exemplary materials include titanium or steel. The force-transfer member 34 may be formed or cast, or made by any other suitable manufacturing process. The force-transfer member 34 may be a unitary component.

The shock-absorbent member 40 may be shaped to have a contour that is substantially the same as the contour of the internal surface of the rear portion 11 of the body 5 on one side, and substantially the same as the contour of the plate 37a on the opposing side.

The shock-absorbent member 40 is sized to fill the gap between the plate 37a and the internal surface of the rear portion 11 of the body 5. The shock-absorbent member may be about 1 mm, 2 mm, 3 mm, 4 mm or 5mm wide, for example.

The shock-absorbent member 40 forms an absorbent layer between the force -transfer member 34 and the body 5. The shock-absorbent member 40 captures, absorbs, and disperses impact energy to the rear portion (tail) 11 of the club head 1. The shock- absorbent member 40 enables the force-transfer member 34 to move towards the rear portion 11 of the body 5 during impact with the ball. This advantageously enables the club face 10 to flex relative to the rest of the body 5 during impact with a golf ball, and may assist with sustained and accurate control of the Coefficient of Restitution (COR). The shock-absorbent member 40 may enable the golfer to control his/her shot instantaneously. Follow-through can be absorbed, as can the impact of an offset hit, and the transfer of energy through the club shaft 26.

The shock-absorbent member 40 may be made from any suitable shock-absorbing material. For example, the shock-absorbent member 40 may be made from a shock- absorbent material typically used for known golf club inserts, such as a thermoplastic elastomer, a thermoset polymer, a rubber, or any combination thereof. Thermoplastic elastomers include styrene co-polymers, co-polyesters, polyurethanes, polyamides, olefins and vulcanates. Thermoset polymers include epoxides, polyimides and polyester resins.

The disclosed club head 1 advantageously directs energy through the centre of gravity 42 of the golf club head 1, even when the golf ball does not contact the optimal point of impact 28 on the golf club face 10. The force-transfer member 34 is believed to impart weight and power, and improve direction control, without unduly compromising club speed. The force-transfer member 34 transfers energy to the plate 37, which transfers energy to the shock-absorbent member 40 at the rear of the golf club head 1. The shock- absorbent member 40 reduces the 'shock' of the impact by absorbing energy transferred through the force-transfer member 34 and plate 37. The combination of these

components is expected to enhance the control of height, direction, distance and comfort, once the golf ball has been struck.

A golf club has a shaft 26 connected to the golf club head 1 via the hosel 20. The shaft 26 could be any suitable type, such as steel or graphite, for example.

The angle of the club face 10 relative to a longitudinal axis D-D of the shaft 26 when viewed from the side defines a loft angle of the club face 10. In the embodiment shown in figures 1-10, the loft angle is about 0° (the club face 10 and the longitudinal axis D-D of the shaft 26 are substantially parallel when viewed from the side).

The elongate portion 38 of the force-transfer member 34 is arranged to substantially align with a direction of movement of the golf club head 1 when the golf club is swung by a user.

Generally, golf ball travel distance is a function of the total kinetic energy imparted to the ball during impact with the club head, neglecting environmental effects. During impact, kinetic energy is transferred from the golf club and stored as elastic strain energy in the club head and as viscoelastic strain energy in the ball. After impact, the stored energy in the ball and in the golf club head is transferred into kinetic energy in the form of translational and rotational velocity of the ball, as well as the golf club. Since the collision is not perfectly elastic, a portion of energy is dissipated in club head vibration, and in viscoelastic relaxation of the ball. The efficiency of the collision between the ball and the club head is known as the Coefficient of Restitution (COR).

The Coefficient of Restitution (COR) is essentially a measure of the efficiency of collision between two objects. In golfing vernacular, the COR is referred to as the 'trampoline effect'. The 'trampoline effect' describes the club face 10 resiliently deforming during impact with a ball, and acting like a spring to propel the ball forward. If a ball is struck closer to the centre of the club face 10, it will be subject to a greater 'trampoline effect' than if the ball were struck near the edge of the club face 10.

While the USGA has specified a limit for maximum COR (83%), there is no specified region in which COR can be maximized, unless it occurs at the exact optimum point of contact (the 'sweet spot'). Accordingly, significant latitude is allowed when the formal issue of COR is addressed or challenged.

COR is determined as follows:

Where:

Vciub-post is the velocity of the club after impact;

Vbaii-post is the velocity of the ball after impact;

Vciub-pre is the velocity of the club before impact; and

Vbaii-pre is the velocity of the ball before impact (typically zero).

The surface area of the point of contact between the plate 37 and the club tail 11 via the shock-absorbent member 40 of the disclosed club head 1 may be less than one fifth (by scale) of the surface area of a contemporary club face. Therefore, COR can be managed very accurately. While flexion of the club face 10 will remain, that movement will be channelled, directed, focussed and then absorbed at the rear of the club head 1. The plate 37 and shock-absorbent member 40 can be structured, by size, and type of shock- absorbent material used in the shock-absorbent member 40, to ensure optimum benefit of the 'trampoline effect' is achieved. Figure 7 shows side section view of a first alternative embodiment of a golf club head 101. The golf club head 101 has similar features and functionality to the golf club head 1 shown in figures 2-10, except as described below. Like numbers indicate like parts, with the addition of 100.

In the embodiment shown in figures 3 and 5-6, the club face 10 has a loft angle of about 0°. In other words, the club face 10 extends substantially in the vertical direction.

However, in practice, most club heads have a loft angle of greater than 0°. Typically, the 1-wood has a loft angle between 7°-13°, a 3-wood has a loft angle between 12°-17°, a 5-wood has a loft angle between 20°-23°, and fairway/ rescue woods have loft angles between 25°-28°.

In the first alternative embodiment shown in figure 7, the club face 110 of the golf club head 101 has a loft angle oi of more than 0°. In other words, the club face 110 is angled at a loft angle oi relative to the vertical direction. The loft angle oi may be any suitable angle. For example, the loft angle oi may be about 5°, 7°, 10°, 12°, 15°, 20°, 25° or 30°.

To accommodate the loft angle oi while still passing through the centre of gravity 142 of the club head 101, the elongate portion 138 of the force-transfer member 134 extends at an angle 02 of less than 90° from the club face 110 in the vertical plane. For example, the elongate portion 138 of the force-transfer member 134 may extend at an angle 02 of about 85°, 83°, 80°, 78°, 75°, 70°, 65° or 60° from the club face 110 in the vertical plane.

The angle 02 at which the elongate portion 138 of the force-transfer member 134 extends from the club face 110 is proportional to the loft angle oi. For example, oi and 02 may add to 90°.

Prior to the 1990's, when the size and internal volumes of club-heads began to increase dramatically, the vast majority of club heads had a relatively symmetrical form where an axis extending from the optimum point of impact (the 'sweet spot') to the rearmost point of the rear portion (tail) of the club head extended substantially at right angles to the club face.

It is now estimated that approximately 30 percent of Number 1, 2 and 3 woods have a tail that is offset in relation to the club face. The club body and the crown of the club head become longer, when facing away from the golfer, while the reverse is now often the case, with the tail of the club head becoming closer to the golfer as he/she addresses the ball. Therefore, the offset angles at which the club face, and tail intersect, are similar to the above described in relation to the loft angle, in the horizontal plane. Figure 8 shows a top section view of a second alternative embodiment of a golf club head 201. The golf club head 201 has similar features and functionality to the golf club head 1 shown in figures 2-10, and the golf club head 101 shown in figure 8, except as described below. Like numbers indicate like parts, with the addition of 200 and 100 respectively.

In the embodiment shown in figure 4, the axis C-C extends at an angle of about 90° relative to the club face 10 in the horizontal plane. In the second alternative embodiment shown in figure 8, the rear portion (tail) 211 of the body 205 is offset to one side, and the axis C-C, which passes through the centre of gravity 242, is offset by an angle bi relative to an axis E-E that extends from the optimal point of impact 228 at an angle of 90° to the club face 210. The axis C-C may be offset from the axis E-E by any suitable offset angle bi. For example, the offset angle bi may be about 1°, 2°, 4°, 6°, 8° or 10°.

To accommodate the offset angle bi while still passing through the centre of gravity 242 of the club head 201, the elongate portion 238 of the force-transfer member 234 extends at an angle b2 of less than 90° from the club face 210 in the horizontal plane. For example, the elongate portion 238 of the force-transfer member 234 may extend at an angle b2 of about 89°, 88°, 86°, 84°, 82° or 80° from the club face 210 in the horizontal plane.

The angle b2 at which the elongate portion 238 of the force-transfer member 234 extends from the club face 210 is proportional to the offset angle bi. For example, bi and b2 may add to 90°.

The club head of the present disclosure can be readily adapted to incorporate other advantageous modifications. For example, interaction between the club head and the playing surface can affect the distance and accuracy of a golf shot, particularly with clubs such as fairway woods and hybrid clubs, which are designed for hitting a ball resting directly on the playing surface.

Drag, created by friction between the sole of the club head and the playing surface can reduce the speed of the swing and the resultant velocity and distance of the shot.

Additionally, forces between the club head and the playing surface can twist or otherwise alter the direction or orientation of the club head at point of impact, which can also reduce distance, velocity, and accuracy, as well as imparting unwanted spin on the ball.

A modification of the club face of the present disclosure adds weight to the foot and sole of the club head, moving the centre of gravity of the club head closer to ground level, while retaining the characteristics of the force-transfer member and shock-absorbent member at the tail of the club head. Figure 9 shows a side section view of a third alternative embodiment of a golf club head 301. The golf club head 301 has similar features and functionality to the golf club head 1 shown in figures 2-10, the golf club head 101 shown in figure 8, and the golf club head 201 shown in figure 9, except as described below. Like numbers indicate like parts, with the addition of 300, 200 and 100 respectively.

In this embodiment, a weighted portion 344 is included behind the club face 310 near the sole 318 of the club head 301. In the embodiment shown, the force-transfer member 334 includes the weighted portion 344. The weighted portion 344 is arranged to lower a centre of gravity 342 of the golf club head 301. The lower centre of gravity 342 causes the optimal point of impact 328 to shift nearer to the toe 324 of the golf club head 1. In alternative embodiments, the weighted portion 344 may be arranged to shift the centre of gravity 342 in other directions.

Depending on the geometry of the club head 1, the elongate portion 338 of the force- transfer member 334 may extend at an angle of less than 90° from the club face 310. In the embodiment shown in figure 9, the elongate portion 338 of the force-transfer member 334 extends at an angle y of less than 90° from the club face 310 in the vertical plane. In other embodiments, the elongate portion 338 of the force-transfer member 334 may extend at an angle of less than 90° from the club face 310 in other planes, such as the horizontal plane.

Referring to figure 9, the axis C-C is coaxial with the elongate portion 338. The elongate portion 338 may extend from the club face 310 at any suitable offset angle y so that the axis C-C passes through the optimal point of impact 328 and the centre of gravity 342 of the club head 301. For example, the elongate portion 338 of the force-transfer member 334 may extend at an angle y of about 89°, 87°, 85°, 82°, 80°, 77°, 75° or 70° from the club face 310 in the vertical plane. In an alternative embodiment, the elongate portion 338 of the force-transfer member 334 extends at an angle y of about 90° from the club face 310 in the vertical plane.

In the embodiment shown, the weighted portion 344 is integrally formed with the tapered portion 336a of the force-transfer member 334. For example, the weighted portion 344 may be formed by an enlarged region of the tapered portion 336a of the force transfer member 334. Alternatively, the weighted portion 344 may be a separate component.

It will be appreciated that the force-transfer member 34, 134, 234, 334 could be readily adapted to incorporate two or more of the alternative embodiments described above. Figures 10-14D show a fourth alternative embodiment of a golf club head 401. The golf club head 401 has similar features and functionality to the golf club heads 1, 101, 201, 301 shown in figures 1-6, 7, 8, and 9 except as described below. Like numbers indicate like parts, with the addition of 400, 300, 200 and 100 respectively.

In this embodiment, the golf club head 401 comprises a removable adjustment component 451 to enable a user of the golf club head 401 to adjust the performance of the golf club head.

The removable adjustment component 451 is insertable into, and removable from, an aperture 471 in the rear portion 411 of the golf club head 401.

When inserted in the aperture 471, the removable adjustment component 451 places the second end 437 of the force transfer member 434 in communication with the rear portion 411 of the body 405 of the golf club head 401. In particular, the removable adjustment component is arranged to transfer force from the second end 437 of the force transfer member 434 to the rear portion 411 of the body 405 when the club face 410 strikes a ball.

The removable adjustment component 451 comprises a shock-absorbent member 440 that is located between the second end 437 of the force-transfer member 434 and the rear portion 411 of the body 405. The shock-absorbent member 440 comprises shock- absorbent material. The material may comprise any one or more of the materials outlined above in relation to shock-absorbent member 40.

The shock-absorbent member 440 in the removable adjustment component 451 comprises a shock-absorbent member having a first property. The removable adjustment component 451 is removable from the golf club head 401 and replaceable with a first alternative removable adjustment component 451' that comprises a shock-absorbent member 440' having a second property that differs from the first property. A plurality of removable adjustment components 451, 451', 451" may be provided, each removable adjustment component 451 comprising a shock-absorbent member 440, 440', 440" having a property that differs from the other shock-absorbent members. For example, each shock-absorbent member 440, 440', 440" may comprise a respective stiffness, so that a first removable adjustment component 451 has a shock-absorbent member 440 with a first, intermediate stiffness, a second removable adjustment component 451' has a shock-absorbent member 440' with a second, lower stiffness, and a third removable adjustment component 451" has shock-absorbent member 440" with a third, higher stiffness that is higher than the first stiffness and the second stiffness. Removing the first removable adjustment component 451 and replacing that with the second removable adjustment component 451' will reduce the Coefficient of Restitution of the golf club head 401, whereas replacing the first removable adjustment component 451 with the third removable adjustment component 451" will increase the Coefficient of Restitution of the golf club head 401.

The shock-absorbent member 440 of the first removable adjustment component 451 may comprise a first shock-absorbent material having a first elastic modulus. The shock- absorbent member 440' of the second removable adjustment component 451' may comprise a second shock-absorbent material having a second elastic modulus that is lower than the first elastic modulus. The shock-absorbent member 440" of the third removable adjustment component 451" may comprise a third shock-absorbent material having a third elastic modulus that is higher than the first elastic modulus and the second elastic modulus.

Additionally, or alternatively, the shock-absorbent member 440 of the first removable adjustment component 451 may have a physical shape or configuration that provides the first, intermediate stiffness. The shock-absorbent member 440' of the second removable adjustment component 451' may have a physical shape or configuration that provides the second, lower stiffness. The shock-absorbent member 440" of the third removable adjustment component 451" may have a physical shape or configuration that provides the third, higher stiffness.

Figures 11-14D show an exemplary configuration of a removable adjustment component 451. It will be appreciated that the alternative removable adjustment components 451', 451" may have a corresponding configuration with different properties for the shock- absorbent members 440', 440".

The removable adjustment component 451 comprises an elongate tubular member comprising a hollow sleeve 453 defining a cavity 455, and a head 457 at one end of the sleeve 453.

A tool-engagement recess 457a is provided in the head 457 to enable a hand-tool to be used to rotate the removable adjustment component 451 to engage it with the body 405 of the golf club head 401 or disengage it from the body 405 of the golf club head 401.

The removable adjustment components 451, 451', 451" and the body 405 of the golf club head 401 comprise complementary engagement features for engaging the removable adjustment component 451 with the body 405 of the golf club head 401. In the form shown, the aperture 471 in the rear portion 411 of the golf club head 401 comprises a plurality of radially inwardly extending projections 473. The removable adjustment component 451 comprises a plurality of radially outwardly extending projections 459 adjacent to, but axially spaced from the head 457.

The projections 459 are configured to extend between the projections 473 in a first angular orientation of the removable adjustment component 451. The projections 459 are configured to engage with the projections 473 in a second angular orientation of the removable adjustment component 451.

One or more of the projections 459, 473 may comprise positive engagement feature(s) to maintain the projections 459, 473 in engagement with each other in the second angular orientation of the removable adjustment component.

In the configuration shown, the positive engagement features comprise an axially- directed protrusion 459a on one or more of the projections 459 that is configured to engage with a complementary recess (not shown) on one or more of the projections 473. Alternatively, one of more of the projections 473 may comprise the axially-directed protrusion and one or more of the projections 459 may comprise the complementary recess.

When the removable adjustment component 451 is inserted into the rear portion 411 of the body 405, the second end 437 of the force transfer member 434 is telescopically received in the cavity 455 in the sleeve 453 of the removable adjustment component 451. The shock-absorbent member 440 is positioned at the head end of the cavity 455 in the sleeve 453. The second end 437 of the force transfer member 434 contacts the shock-absorbent member 440. The second end 437 of the force transfer member 434 may compress the shock-absorbent member 440 to preload the club face 10.

When the club face 10 strikes a ball, the club face 10 deforms and the removable adjustment component 451 transfers force from the second end 437 of the force transfer member 434 to the rear portion 411 of the body 405 via the shock-absorbent member 440. The shock-absorbent member 440 compresses during that force transfer, with the extent of compression depending on which removable adjustment component 451, 451', 451" is used in the golf club head 401.

It will be appreciated that the removable adjustment components 451, 451', 451" and the force transfer member 434 could have any suitable configuration. For example, the force transfer member 434 may have a plate at its second end 437, as shown in relation to figures 1 to 9. The sleeve 453 of the removable adjustment component may be shaped accordingly. The removable adjustment components 451, 451', 451" and the body 405 of the golf club head 401 could have a different configuration of complementary engagement features from those shown. By way of example, the removable adjustment components 451, 451', 451" and the body 405 of the golf club head 401 could have complementary screw threads to enable the removable adjustment components 451, 451', 451" to be engaged with, and disengaged from, the body 405 of the golf club 401 head via a screw action. Any suitable alternative configuration of complementary engagement features could be used.

Rather than being inserted from the rear portion 411 of the body, the removable adjustment component 451 may be insertable from the top or bottom of the golf club head 401, to be received between, and provide communication between, the second end 437 of the force transfer member 434 and the rear portion 411 of the body 405 of the golf club head.

The removable adjustment component 451 may be used with any of the golf club heads described above.

In addition, any of the embodiments described above may be used in conjunction with any other known developments for golf club heads, such as polymeric inserts.

A user of the golf club head 1, 101, 201, 301, 401 described above is expected to benefit from increased control over the distance, height and direction of a golf ball, once struck, due to the concentration of energy at the optimal point of contact between club face and the golf ball via the COG. This is due to the fact this club face is not isolated, as a stand alone flexible component of the club head. The concave internal structure of this design focusses impact to the centre of the club face and is expected to mitigate the negative impact of uncontrolled miss-hits via the COR ('trampoline-effect') of contemporary club face design.

The unitary structure of the club head of the present disclosure is expected to increase the ability of the player to plan and control a given shot, with increased confidence. This is because issues pertaining to the outcomes of a miss-hit from a contemporary club face, where size and flexion is problematic, can be mitigated. As energy is transferred to the rear portion of the club head in alignment with the optimal point of impact and the centre of gravity, the extreme negative effects of miss-hits may be considerably reduced.

The golf club head is also expected to provide the user with an audible response to a successful shot. The sound of the impact between golf ball and the club face of a golf club head provides the golfer an immediate opportunity to determine whether the golf club has impacted the golf ball at the point where it will obtain the maximum distance, or whether the direction of the ball has not met the preferred requirements of the golfer. Nominally, a sharp, crisp sound will indicate a preferred shot, whereas the sound of a miss-hit can vary from a thump, to a strident 'wrench' if the golf ball is struck closer to the outer perimeter of the club face. The present disclosure, by mitigating the negative effects of a miss-hit and absorbing the energy of contact via the plate and shock- absorbent member, will produce a strong and 'solid' sound, as impact energy is spread in graduated form, due to the concave design of the internal club face (the club face typically being convex when viewed from the front).

The described embodiments are expected to provide the golfer with comfort and feel, immediately following point of contact between club face and golf ball. A miss-hit from a club head that is devoid of internal support will transmit energy violently and directly to the club grip, via the club shaft. This can impact and negate the effect of a positive follow-through. It can also cause the club shaft to twist, with the effect radiating trough the club grip to the hands of the user, creating discomfort. The internal features of the described embodiments focus the energy from substantially all strokes to the centre of gravity of the club head. Thereafter, that energy is transmitted, regardless of a perfect or miss-hit, directly through the centre of gravity of the club head to the tail of the club head. The shock of the impact is absorbed by shock-absorbent member at the tail of the club head.

The fractional time difference between uncontrolled energy impact at the club face and energy absorption at the tail of the club head, may positively impact follow-through. Furthermore, as there is a tightly focussed (by volume) area of shock-absorption at the rear portion of the club head, there is less likelihood of negative shock transmission through the club shaft to the club grip and ultimately, the golfer. The effects of negative control, shock and feel may be mitigated.

In addition, the described embodiments advantageously do not substantially increase the weight of a golf club head compared with most contemporary golf club head designs. While adding weight within the hollow interior of a golf club head, the overall weight of the club head will not increase; neither will club-speed decrease. This is because most conventional clubs of this type, to offset the negative results of a miss-hit, contain a number of perimeter weights, which add weight to the club head. These weights are nominally fixed, or interchangeable (by weight). Additionally, metal inserts may be used adjacent to the club face, to deflect energy, or support shock-absorbent material. These weights require a point of fixed location within the club head, nominally in the base and/or side or rear of the club body. The weights may also be adjusted, to move directionally within the club head. To accommodate these weights, additional weight is required, via a casting, within the club head. The described embodiments reduce the need for perimeter weights, and the internal castings that accommodate them.

The described embodiments are expected to benefit any club design that has a substantially hollow interior, regardless of club size and internal volume. The design negates, for example, the requirement for perimeter weighting or the placement of shock-absorbent material within or adjacent to the club face. Equally beneficial is the opportunity for legitimate and specific control over the COR (Coefficient of Restitution) or the 'trampoline' effect.

The golf club heads described above are designed to achieve maximum distance and/or height, and may drive a golf ball over 200 metres.

Golf club heads having force-transfer members 34, 134, 234, 334, 434 as described above may also have beneficial effects for clubs designed for accurate control and direction of the golf ball over a short distance, such as putters.

The golf club head embodiments described above can readily be adapted for a putter.

The components of the putter have the same features and functionality as described above, but scaled to fit within a hollow, putter-sized head.

A putter will nominally be utilized on the most pristine golfing grass surface of a given 'hole'; the 'green'. The vast majority of golfers, recreational and professional, are satisfied if they can 'hole' the golf-ball via two strokes with a putter, once the ball is on the green, or very close to the green surface.

Many contemporary putters contain thermo-elastic polymer inserts on, or within the club face to provide comfort, 'feel', and control for the user, via the club-head to the shaft and club-grip. By contrast, the described features may place shock-absorbent material at the rear of the club-head.

Utilisation of the described features in a putter advantageously improves the accuracy of the shot in the case of a miss-hit, by directing the force of the impact between the club head and the golf ball through the centre of gravity of the club head.

The user is expected to achieve beneficial control and distance over a prescribed shot, as the preferred/desired point of impact between club and ball is adjoined via the force- transfer member within the club body, which follows a direct axis between the ball, club face, rear portion of the club, and the desired initial ball travel path to the cup/hole. The placement of the shock-absorbent member at the rear portion of the club is expected to benefit the user by focussing the transmission of energy to a small, finite area of the club, as opposed to the transmission of energy across a significantly larger club face at point of impact; the latter contributing to a possible miss-hit. The alignment of the putter face, ball, and desired initial ball travel path to the cup/hole, is important for an accurate putt. If a golfer is able to strike a ball at the centre of the club, impact will transmit through the club at a perfect axis to the point of impact.

Preferred embodiments of the invention have been described by way of example only and modifications may be made thereto without departing from the scope of the invention.