Protection device

Abstract

The present invention provides body part protectors which comprise multiple discrete and optionally removable/replaceable shock absorbing elements. The body part protectors of this invention offer superior protection to body parts such as knees and elbows as compared to other devices and/or those devices which comprise single shock absorbing elements.

Claims

1. A device for protecting a joint, said device comprising: a body part contact portion; a surface contact portion; and a plurality of discrete shock absorbing elements disposed between the body part contact portion and the surface contact portion; wherein the shock absorbing elements are circumferentially arranged around a vertical axis located in the centre of the surface contact portion; wherein the shock absorbing elements comprise springs; wherein the body part contact portion and the surface contact portion comprise a plurality of shock absorbing element housings, each shock absorbing element being associated with at least one shock absorbing element housing; wherein the device comprises a plurality of flexible members extending between the body part contact portion and the surface contact portion and configured to prevent the shock absorbing elements from breaking free of the housings, each shocking absorbing element being associated with at least one of the flexible members wherein the plurality of flexible members are flexible cords designed to be fed through each of the plurality of the discrete shock absorbing elements.

2. The device of claim 1, wherein the joint is a knee joint or an elbow joint.

3. The device of claim 1, wherein in use, there is no shock absorbing element located directly under an apex of the joint or the shock absorbing elements are circumferentially arranged around the joint.

4. The device of claim 1, wherein one or more of the discrete shock absorbing elements is capable of removal from the device.

5. The device of claim 1, wherein the shock absorbing elements are each independently removable or interchangeable.

6. The device of claim 1, wherein the body part contact portion and the surface contact portion define ports for releasably receiving the shock absorbing elements.

7. The device of claim 1, wherein the shock absorbing elements are capable of being arranged or distributed in a plurality of configurations.

8. The device of claim 1, wherein the shock absorbing elements are capable of being alternated, replaced or interchanged with shock absorbing elements of low, medium or high stiffness, deformability, spring rate or compression properties.

9. The device of claim 1, wherein the device further comprises a fastening for releasably securing the device to or around a joint to be protected.

10. The device of claim 1, wherein the surface contact portion or body part contact portion comprises one or more materials selected from the group consisting of: (i) a hard or resilient material or materials; (ii) metal; (iii) plastic; (iv) rubber; (v) wood; (vi) fabric; (vii) composite materials; and (viii) any combination of (i) to (vii).

11. The device of claim 1, wherein the body part contact portion comprises a cradle which accommodates, houses or fits against or around or at least partially encloses the joint to be protected.

12. The device of claim 1, wherein the body part contact portion comprises a layer of padding or wadding that, in use, cushions the joint.

13. The device of claim 1, wherein the surface contact portion comprises a solid or continuous component.

14. The device of claim 1, wherein the surface contact portion comprises a substantially flat or planar surface for contact with a surface.

15. The device of claim 1, wherein the surface contact portion comprises a sole or surface protecting layer.

16. The device of claim 15, wherein the sole or surface protecting layer increases the grip of the device on a surface.

17. The device of claim 1, further comprising a flexible sheath disposed between the body part contact portion and the surface contact portion, the sheath being adapted to protect the shock absorbing elements from the ingress of debris.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be described with reference to the Figures which show:

(2) FIG. 1: Picture of a body part protecting device 10 according to one embodiment of the invention.

(3) FIG. 2: 3D drawing of a perspective view of the body part protecting device 10 shown in FIG. 1.

(4) FIG. 3a: Side view of a body part protecting device 20 according to another embodiment of the invention.

(5) FIG. 3b: Side view of the body part protecting device 20 shown in FIG. 3a.

(6) FIG. 3c: Top view of the body part protecting device 20 shown in FIGS. 3a and b.

(7) FIG. 4a: Side view of a body part protecting device 30 according to an embodiment of the invention.

(8) FIG. 4b: Front view of the body part protecting device 30 shown in FIG. 4a.

(9) FIG. 4c: Top view of the body part protecting device 30 shown in FIGS. 4a and b.

(10) FIG. 5a: Picture of a shock absorbing unit 40 comprising a resilient element (spring) located in the resilient element housings according to an embodiment of the invention.

(11) FIG. 5b: Picture of the shock absorbing unit 40 shown in FIG. 5a releasably secured to the surface contact portion and the body contact portion of a device according to one embodiment of the invention.

(12) FIG. 6: Picture of a body part protecting device 60 according to a further embodiment of the invention.

(13) FIG. 7a: Top view of body part protecting device 70 according to another embodiment of the invention.

(14) FIG. 7b: Side view of body part protecting device 70.

(15) FIG. 7c: Longitudinal cross-section of body part protecting device 70.

(16) FIG. 7d: Front view of body part protecting device 70.

(17) FIG. 7e: Cross-section of body part protecting device 70.

(18) FIG. 8: Graph displaying the % reduction in peak knee pressure measured on the device of the present invention (VH Innovation) and six other top-of the range commercially available knee pads.

(19) FIG. 9: Image of the side view of body part protecting device 80.

(20) FIG. 10: Image of the top view of body part protecting device 80.

(21) FIG. 11: Image of the back view of body part protection device 80.

DETAILED DESCRIPTION OF THE INVENTION

(22) The present invention will now be described by way of example and with reference to the accompanying drawings.

(23) FIG. 1 is an image of body part protection device 10 according to one embodiment of the invention. The device comprises a curved body contact portion 2 comprising a hard material layer 2a, such as hard plastic. The body contact portion 2 is formed and adapted to receive the body part to be protected, in this case a knee. The body part contact portion 2 of device 10 further comprises a layer of padding or wadding 2b adjacent the layer of hard material 2a. In use, the wadding 2b is directly in contact with the knee and offers the user comfort and prevents direct contact between the knee and the hard material of part 2a. Body part contact portion 2 further comprises layer 2c which is bonded to the layer of hard material 2a and provides a means for attaching straps 8 to the device.

(24) Device 10 further comprises surface contact portion 4, having a curved profile which, in this embodiment mirrors or mimics the shape and general curvature of body contact portion 2. The surface contact portion 4 comprises a curved convex surface which, when the device is in use, is in contact with the surface. The convex profile allows the user to rock, shift and/or slide on or across a surface. In use, the curved/convex surface of surface contact portion 4, enhances the user's mobility and their general safety.

(25) Body part contact portion 2 and surface contact portion 4 are spaced apart by means of a plurality of discrete shock absorbing elements 6, which in this embodiment take the form of springs. This figure shows only some of the shock absorbing elements and these have been allocated reference numerals 6a through to 6e.

(26) One end of each shock absorbing element 6 is connected to the body part contact portion 2 and the other end of each shock absorbing element is connected to surface contact portion 4. In this embodiment, the shock absorbing elements 6 are distributed in rows and they are the only component that bridges the space between the body contact portion and the surface contact portion of device 10 (indeed this is a feature of all of the body part protectors provided by this invention).

(27) In this embodiment, four of the shock absorbing elements 6b-6e extend from part 2c of the body contact.

(28) In use, the pressure exerted on a body part upon contact with the body part contact portion 2 is absorbed by the plurality of shock absorbing elements 6, which act as resilient spacers maintaining a (variable) distance between the body part contact portion 2 and the surface contact portion 4.

(29) Device 10 further comprises straps 8, which are attached to part 2c of the body part contact portion. When device 10 is in use, straps 8 are secured to the user such that the device 100 protects the appropriate body part. The device 10 of this embodiment is to be secured to the body such that the body part contact portion is placed adjacent a kneein this way device 10 offers protection to a knee against contact against a surface. Device 10 may be secured to a knee by fastening one of two straps 8 around an upper part of the leg (for example around part of the thigh) and the other strap around a lower part of the leg (for example around part of the calf).

(30) Straps 8 comprise fastening means such as hook and loop fastening means (not shown here) to releasably secure the straps around a suitable body part and thereby secure the device to the user's body.

(31) FIG. 2 is a 3D perspective representation of the same device 10 shown without straps and wadding. Similar features have been identified using the same reference numerals. In this figure the curved profile of the surface contact portion 4 can be best appreciated. The body part contact portion 2 (shown without wadding layer 2b) is shown as comprising a moulded cradle 2a which fits around and/or adjacent the knee. Cradle 2a which may be made of a hard plastic material, defines central well 2d adapted to receive a user's knee and accommodate movement thereof. In this embodiment, surface contact portion 4 is shown to comprise grooves or ribs 4a that in use may improve a user's grip on a surface.

(32) FIGS. 3a and b represent side views and FIG. 3c represents a top view of a further body part protection device 20 according to an embodiment of this invention. Again, device 20 is adapted to provide a user with protection for a knee.

(33) Device 20 comprises body part contact portion 22 which in this embodiment takes the form of moulded cradle adapted to enclose, surround, engage, accommodate or fit with, around or against a knee (not shown). The outer surface of the body part contact portion 22 (the surface that is not in direct contact with the knee) is curved and it defines a series of ribs 22c (best appreciated in FIG. 3b). Ribs 22c provide additional strength and increase the compression of the shock absorbing elements 26 (shown in FIGS. 3a and 3b are shock absorbing elements 26a, b and c), thus allowing the shock absorbing elements 26 to fully compress into a recess (not shown) in order to provide improved stability. Body contact portion 22 further defines rim 22b that provides a means for attaching straps (not shown) which may be used to secure the device 20 to the leg of the user in order to protect the knee of the user. Body contact portion 22 also comprises a cradle of hard material 22a.

(34) Device 20 further comprises surface contact portion 24 which in this embodiment is a continuous curved/domed unit which, when device 20 is in use and placed against a surface, provides a single point of contact with the surface. Both the inner and outer surfaces of surface contact portion 24 are curved.

(35) The shape and/or form of surface contact portion 24 allows the user to move or rotate or displace their bodyweight without shifting across the surface. Moreover, the shape and design of the surface contact portion 24 enhances the user's mobility across the contact surface. The surface area of the surface contact portion 24 is smaller than that of body contact portion 22. This enhances the mobility of the user as in use, body contact portion 22 can move independently of the surface contact portion; furthermore, the movement of body contact portion 22 is not substantially or unduly impeded by surface contact portion 24. The smaller size of surface contact portion 24 also reduces the manufacturing cost of device 20.

(36) FIG. 3b presents a side view of device 20 and best shown here is the inner profiled surface of surface contact portion 24 which defines grooves or channels 24a to accommodate the ribs 22c of the body contact portion 22.

(37) Body part contact portion 22 and surface contact portion 24 are spaced apart by a plurality of the shock absorbing elements designated 26a-c. One end of each shock absorbing element 26a-c is connected to body part contact portion 22 and the other end of each shock absorbing element 26a-c is connected to surface contact portion 24.

(38) In this embodiment, the shock absorbing elements 26a-c are the only elements located (or disposed) in the space between the body contact portion 22 and surface contact portion 24.

(39) FIGS. 4a-c provide side, front and top views of a knee protection device 30 according to a further embodiment of the invention. Device 30 comprises body contact portion 32, surface contact portion 34 and a plurality of shock absorbing elements 36 which are disposed therebetween.

(40) In FIGS. 4a-4c, body part contact portion 32 is represented as having a substantially flat surface to contact a body part, but the skilled person will understand that other shapes and forms of body contact portion 32 are envisaged and within the scope of this invention, for example, body contact portion 32 may be curved so as to accommodate an elbow or knee.

(41) In this embodiment, body contact portion 32 is rectangular in shape and comprises it hard base 32a which defines a tray or pocket into which a layer of padding or wadding 32b is packed or placed. The wadding or padding 32b serves as a cushion between the body part and the hard base material of body part contact portion 32a. The layer of padding or wadding 32b may comprise a soft material, for example a silicone, (encapsulated) gel, plastic, fabric, sponge and/or rubber material.

(42) Body part contact portion 32 has a larger surface area than surface contact portion 34.

(43) Surface contact portion 34 is circular in shape and the surface which domed or curved curved (convex) on the contact surface side. In use, this ensures that the surface contact portion 34 is in contact with a surface through a single point of contact and it enables the user to shift their body weight, rotate a protected body part by up to 360 and shift or move across the surface easily (for example while crawling and/or sliding).

(44) The plurality of discrete shock absorbing elements 36a-f are disposed between body part contact portion 32 and the surface contact portion 34; in this embodiment they are distributed in a circular configuration. This provides an even distribution of the user's weight across the entire surface of surface contact portion 34 and assists the user shifting the body weight towards one side of the device, for example while rocking and/or moving across a surface. This feature greatly enhances the mobility of the user, while providing adequate protection for a body part.

(45) Shock absorbing elements 36 are releasably attached to body contact portion 32 and surface contact portion 34. In this embodiment, shock absorbing elements 36 are releasably attached to body contact portion 32 and surface contact portion 34 by means of shock absorbing element housings 38.

(46) In FIGS. 4a and 4b, spring housings 38a and 38b are shown as located at each end of each shock absorbing element 36. Shock absorbing element 36 and each shock absorbing element housing 38a and 38b define a shock absorbing unit 40 (see FIG. 5) which is fixed between body contact portion 32 and surface contact portion 34.

(47) FIG. 4c best shows the circular configuration of the shock absorbing elements 36a-f.

(48) FIGS. 5a and b are images an individual shock absorbing unit 40 that might be used with a device of the present invention. These shock absorbing units may be sold individually or in kits for replacing broken shock absorbing units and/or for altering the resilience/resistance of a body part protection device of this invention.

(49) Shock absorbing unit 40 comprises a shock absorbing element 42 (a spring) shock absorbing element housings 44a and b which are attached to either end of shock absorbing element 42. In FIG. 5b the shock absorbing units 40 are shown in use and attached to a device of the invention. Housing 44a is releasably attached to a port or aperture of the body contact portion 48 of a device of the present invention and housing 44b is releasably attached to a port or apertures (not shown) of the surface contact portion 50. The housings 48 may be attached to the device by means of screws that fit into the built in screw thread 46 of the housing of the shock absorbing unit 40.

(50) FIG. 6 is an image of body part protection device 60 according to another embodiment of the invention. The device comprises a body part contact portion, which encompasses a concave metal mesh cradle 62a adapted to receive a body part, for example a knee. The device further comprises a layer of padding or wadding 62b on the inside surface of the body part contact portion, which serves as a cushion between the body part and the hard metal mesh of the body contact portion. The device further comprises a plurality of springs acting as shock absorbing elements 66a-d, disposed between the body contact portion and the surface contact portion. One end of each shock absorbing element is connected to the outside surface of the body part contact portion (i.e. the surface which does not face the body part to be protected) and the other end of each shock absorbing element is connected to the inside surface of the surface contact portion. In this embodiment, the shock absorbing elements 66a-c are enclosed in a tubular body or housing and the shock absorbing element 66d is attached to the surface contact portion, perpendicular to the other shock absorbing elements, in order to maintain the curved shape of the surface contact portion. The surface contact portion comprises a hard material 64a, which is curved to allow for rotation and/or movement of the device when in use, without displacement of the protective device across the surface or to provide mobility when the user wants to shift/move across the contact surface. Furthermore, the surface contact portion 64a is solid and/or continuous to provide a single point of contact with the surface wherein in use and it comprises a surface contact sole 64b made of a soft gripping material to provide better grip of the device on the surface. The device also comprises strap holders 68a and b to provide a means of securing straps (not shown here) for attaching the device to locations above and/or below (for example either side of) the knee and/or elbow.

(51) FIGS. 7a-e show top, side, longitudinal cross-section, front and cross-section views of a knee protection device 70 according to a further embodiment of the invention. Device 70 comprises body contact portion 72, surface contact portion 74 and a plurality of shock absorbing elements 76 which are disposed therebetween.

(52) FIG. 7a best shows surface contact portion 74 and the strap holders 73a and b that hold straps 79a and b. Strap 79a is configured to secure device 70 to the thigh of the wearer while strap 79b is configured to secure the device to the shin of the wearer. By means of the straps the device can be securely located and held in position to provide the maximum impact protection to the wearer.

(53) The body contact portion 72 of device 70 consists of an elongated cradle or tray of hard material 72a which is configured to host a layer of padding or wadding 72b for providing additional comfort and pressure release from the wearer's joint. The padding or wadding 72b may comprise any suitable soft material such as rubber, foam, viscoelastic polyurethane foam, (encapsulated) gel, silicone, fabric, sponge and the like.

(54) Body part contact portion 72 has a larger surface area than surface contact portion 74.

(55) Surface contact portion 74 comprises a hard material base 74a to provide stability and a soft material sole 74b to prevent damage of the surface on which the device rests. FIG. 7b clearly shows that surface contact portion 74 has a wedge shape being fatter or thicker at one end than is at the other. As seen in FIGS. 7a and 7b, the surface contact portion sole 74b defines a profiled surface. Without wishing to be bound by theory, the profiled sole 74b may provide additional grip on the surface and prevent sliding or shifting while the wearer performs an activity which involves leaning a joint on a hard surface. The surface contact portion sole may comprise any suitable material such as rubber, plastic, silicone and the like. As best observed in FIGS. 7b-e surface contact portion 74 has a flat profile in order to provide maximum stability on the location on which the joint rests. However, surface contact portion 74a defines rounded edges. This may prevent the user from getting entangled onto obstacles or items that lie on a surface.

(56) As best observed in FIGS. 7b and 7d, device 70 further comprises a flexible and corrugated sheath 77, which encircles the cavity containing the shock absorbing elements 76. Sheath 77 may comprise any suitable flexible material, such as fabric, plastic, rubber and the like. Sheath 77 protects shock absorbing elements 76 from the ingress of dirt, dust, moisture and/or substances that may damage or decrease the performance of the shock absorbing elements. Also shown in this figure are body contact portion 72 which in this image is shown to comprise a part 72a which accommodates the knee and which is lined with a layer of padding or wadding 72b. Further, body contact portion 72 is shown to extend such that it further provides a guard or shield protecting part of the front of the shin. It is from this part of body contact portion 72 through which strap 79b is thread such that it can be affixed around a user's shin.

(57) FIGS. 7c and 7e show cross-sections of the device. As seen in FIG. 7c, device 70 comprises shock absorbing elements (visible here are elements 76a, b, c and d and not visible are 76e and f) which in this embodiment take the form of springs mounted on shock absorbing housings 78a and 78c. In device 70 the 6 shock absorbing elements 76a-f distributed in a circular arrangement. Device 70 is configured to be placed on or against a user's joint and in use shock absorbing elements 76a surrounding the apex or centre point of the joint. Without wishing to be bound by theory, this design may provide an enhanced distribution of the pressure load across the entire device and decrease the strain suffered by the wearer. As such, device 70 may be configured so as not to comprise any shock absorbing element located directly under the apex of the joint of the wearer.

(58) Shock absorbing housing 78a consists of a walled recess defined by the body contact portion 72. Shock absorbing housing 78c consists of an abutment or stump which can extend up into the each spring shock absorbing element 76a-f. The shape and size of shock absorbing housing 78c is configured to match the internal diameter and shape/size of each shock absorbing element 76a-f in order to provide a snug fit and secure the shock absorbing elements in place. Under compression or in use (i.e. when body contact portion 72 is brought towards surface contact portion 74) abutment 78c is configured to fit within recess 78a. Through the centre of each shock absorbing element 76a-f are also provided cord fasteners 78b. Cord fasteners 78b are connected to surface contact portion 74 and body contact portion 72 and are configured to be fed through shock absorbing elements 76. Cord fasteners 78b may comprise any suitable material; for example, cord fasteners 78b may comprise a flexible plastic, string, rubber or the like. Beneficially, cord fasteners 78b may be compressed together with shock absorbing elements 76 and upon return of the shock absorbing elements 76 to the extended (uncompressed) configuration, the cord fasteners 78b may secure the shock absorbing elements 76 in place, not allowing their displacement away from the shock absorbing element housings 78a and 78c. In this embodiment, shock absorbing elements 76a-f are springs and cord fasteners 78b are located within the void of the each spring 76a-f. Without wishing to be bound by theory, this provides additional stability to the shock absorbing elements and prevents lateral displacement. Furthermore, cords 78b assist in the assembly of shock absorbing elements 76a-f onto the device. Shock absorbing housing 78a defines a port or aperture into which the top end of shock absorbing element 76 and cord fastener 78b can be secured. Each cord fastener 78b may take the form of a treasury tag or India tag (i.e. a tag with orthogonal cross-pieces) which can be easily threaded into place. The lower end of each shock absorbing element 76a-f is secured onto shock absorbing housing 78c, as well as the lower end of cord fastener 78b. Shock absorbing housing 78a is defined by body contact portion 72a while shock absorbing housing 78c is secured to or defined by surface contact portion 74a.

(59) FIG. 8 is a graph representing the results of a study aiming to identify the optimum spring characteristic for a joint protection device of the invention and comparing the peak pressures developed on the knee during kneeling with commercially available knee pads. Kneeling poses a risk to the development of medial tibiofemoral osteoarthritis and infrapatellar bursitis. Therefore future knee pad designs should focus on reducing the pressure to the bursa areas along the patellar tendon and tibial tubercle.

(60) Following ethical approval, 5 male and 3 female volunteers were recruited. All self-diagnosed themselves to be free of current knee problems.

(61) Participants performed a double knee descend twice on the floor and the pressure profile across their knee was recorded using a pressure mat (3100, Tekscan Inc., Boston, US) placed between the knee pad and knee. Participants randomly wore six versions of a prototype joint protection device of the invention (VHinnovation) utilising combinations of 22 mm and 25 mm springs each with 6, 8 and 14 N/mm stiffness. Subsequently, participants randomly wore one of six commercial knee pads (Nailers, TommyCo, Snickers, Redbacks, Impacto Red, Impacto Rubber) together with a no knee pad condition.

(62) Peak pressures were normalised by the peak pressure developed during kneeling without a knee pad. ANOVA was used to analyse whether normalised peak pressure varied between knee pads and between genders.

(63) Peak pressure without a knee pad significantly correlated with body mass (r=0.49 p<0.001), but normalised peak pressure did not, giving confidence to the normalization assumption catering for both kinematic and inertial differences between participants. For the joint protection devices of the invention, a gender difference existed whereby, on average across all designs, females reduced their peak pressure by 77+/4% using knee pads, whilst men experienced a 60+/3% reduction (p<0.01). Statistically, there was no difference between the various prototypes of the joint protection device of the invention. However, since the 22 mm 8 N/mm spring had the lowest normalised peak pressure on average, reducing pressure by 76.6+/6%, this design was compared against the other market competitors.

(64) Significant differences were found between pad designs (FIG. 8) with regards to peak pressures (p<0.001). Post hoc t-tests demonstrated the average normalised peak pressure reduction achieved with the new design was significantly better than all other competitor brands with the nearest competitor achieving a 60.7% reduction in peak force. Females reduced their peak pressure by 58.3+/2.9% whilst men obtained a 49.3+/2.6% reduction (p<0.05) across all knee pads.

(65) The joint protection device of the invention adopting 22 mm, 8 N/mm springs achieved significantly greater reductions in peak pressures during kneeling compared to market competitors. Without wishing to be bound by theory, if peak pressures translate into knee injury, then the joint protection device of the invention may have the potential to reduce such pathologies.

(66) FIG. 9 shows an image of the side view of a knee protection device 80 of the present invention. Device 80 comprises a body contact portion comprising an elongated cradle 82 fabricated from a relatively stiff material, that hosts a layer of padding or wadding 82b comprising a soft resilient material. In use, the layer of padding or wadding 82b hosts the user's knee. The components of device 80 are the same as those of device 70 but the layer of padding or wadding 82b extends beyond the cradle to provide wings or flaps which curve up in order to accommodate and surround the user's shin. In use, the layer of padding or wadding 82b hugs the user's shin, securing device 80 in place. Straps 89b are fastened over the layer of padding or wadding 82b while straps 89a are secured to the user's thigh in order to prevent displacement of the device when in use. Device 80 also comprises a surface contact portion 84a, which comprises a surface contact sole or surface protection layer 84b (not shown). The shock absorbing elements of the device (not shown) are covered with a protective sheath 87, which comprises a soft resilient material such as rubber. Sheath 87 may comprise any suitable flexible material, such as fabric, plastic, rubber and the like. Sheath 87 may protect the shock absorbing elements from dirt, dust and/or substances that may damage or decrease the performance of the shock absorbing elements.

(67) FIG. 10 is an image of the top view of device 80. This figure best shows the configuration of the layer of padding or wadding 82b extending beyond the cradle upwards and curving inwards in order to receive a user's knee and surround a user's shin. It can also be observed that straps 89b are fastened over the layer of padding or wadding 82b. Beneficially, this configuration may provide secure location of the device in place while reduce the discomfort that straps attached to the user's leg without a cushioning layer may lead to.

(68) FIG. 11 is an image of a front view of device 80 with surface contact portion 84a leaning against a surface. The curvature of the layer of padding or wadding 82b can be appreciated in this image.

(69) Those skilled in the art will recognise that the above-described embodiments are merely exemplary of the present invention and that various modifications and improvements may be made thereto without departing from the scope of the invention. Furthermore, the various embodiments described above include a number of different features. It will be recognised by those of skill in the art that many of these features offer advantages independently of the other features present in the embodiments and could be incorporated in other aspects of the invention.