FIELD OF INVENTION The present invention relates to a rotatable balancing platform device.

BACKGROUND TO INVENTION Various types of rotatable balancing platform devices for allowing persons, in particular children, to test their ability to keep upright or keep their balance are known. Such devices are also used for purposes of exercising, for instance to train retaining one's balance when skiing.

Some examples of prior devices are as follows: ANBAR (US 3,593, 994) suggests an exercise device comprising a platform adapted to pivot about a base. The platform and base pivot by means of two concentric rings of ball bearings riding in raceways formed from two superimposed plates. The upper plate is attached to the platform and the lower plate is attached to the base. One or more handles are attached to the device.

In US 4,285, 516 (HEATWOLE) there is disclosed an amusement and/or exercising device including first and second pads, each of which pads is adapted to support one leg of a person. The pads are rigidly interconnected together. Each pad has a ground engaging element below and is associated therewith. A generally spherical bearing is provided

between each ground engaging element and its associated pad so that each pad may tilt and/or rotate relative to its ground engaging element.

Gilliam (US 4, 386, 915) discloses a dry land trick ski trainer comprising a circular platform disposed at 2 1/2 to 10 degrees attitude and rotating supported at its center on a base. The circular platform is provided with a ski boot and markings to show the proper placement of feet. A ski rope is provided, one end of which is attached through a pulley to a set of weights so as to simulate the pull of a boat.

HARTZ (US 4,905, 994) describes a tilting rotational device which has a platform on which the user stands. The platform is freely rotatable upon a bearing. The angle of the platform with respect to the horizontal may be adjusted so that a user standing or sitting on the platform may induce rotational movement of the platform easily by shifting his or her center of mass. One or more additional bearings placed internally in the device optionally provide random and unpredictable rotational movements of the platform, depending on the nature of the user's shift of mass. The device may be locked into a particular angle adjustment, and all internal parts may be held securely together to facilitate safe and reliable use.

In US 5, 279, 533 (YIN et al) there is shown a fitness accessory including a seat, a rotary table retained to the seat by a base plate, and a ball bearing retained between the seat and the rotary table, and a back plate detachably fastened to one side of the seat by dovetail joints. The seat has a pair of opposing hand grips when the appliance is used for push ups or sit ups.

The rotary table has external raised portions for rubbing and kneading the

feet when the appliance is turned upside-down on the ground and stepped on.

Clark (US 5,549, 536) describes an inclined rotating platform apparatus, which rotates freely upon a base having an annular ring with at least three legs extending between the annular ring and an inclined collet. Flexible handles extend from opposing sides of the inclined platform to aid in supporting a user thereon. The user shifts his body weight to rotate the inclined platform, thus spinning the user about the base.

In US 5, 766, 119 (CLARK) there is described an inclined rotating platform apparatus which rotates freely upon a base having an annular ring. The inclined platform has handles extending from opposite sides of the inclined platform to aid in supporting the user thereon. The user shifts his body weight to rotate the inclined platform, thus spinning the user about the base.

It is an object of the invention to suggest a new type of rotatable balancing platform device, which can be used by children, even small children, and also grown-ups, and is relatively cheap to produce but reliable in operation.

SUMMARY OF INVENTION According to the invention, a rotatable balancing platform device including a base member having a base engaging surface adapted to be placed on and supported by a support surface; a platform member; and rotational means for rotatably supporting the platform member on the base member; is characterized thereby

a) that the rotational means is adapted to rotationally support the platform member on the base member to rotate about a rotational axis ; b) that the base member includes an integrally formed annular rim and a disc plate; c) that the platform member includes an integrally formed annular rim and a platform disc to support a person thereon; and d) that inclination means is provided for inclining the rotational axis to the base engaging surface at an inclination angle which is less than 90°.

The inclination angle may be between 2° and 10°, preferably 1, 75°.

The rotational means may include a bearing member located centrally between the platform member and the base member.

The bearing member may be a thrust bearing.

The rotational means may include a further bearing held centrally by the base member.

The platform member may have a central hub and a shaft extending from the hub towards the base member, the shaft being held rotationally by the rotational means.

The inclination means may be constituted by the base member being constructed of wedge-shape in side view.

The annular rim of the base member may include a first annular rim part of uniform height and integrally formed therewith a second annular rim part which is of decreasing height from one side towards its other side.

The rotational means may include a threaded bolt screwed from the base member into a threaded cylinder provided centrally in the platform member.

The device may include a handle removably attachable to the platform member.

BRIEF DESCRIPTION OF DRAWINGS The invention will now be described by way of example with reference to the accompanying schematic drawings.

In the drawings there is shown in: Figure 1 a perspective view of a rotatable balancing platform device in accordance with the invention; Figure 2 a plan view seen along arrow II in Figure 1; Figure 3 a side view seen along arrow III in Figure 2; Figure 4 another side view seen along arrow IV in Figure 3; Figure 5 a perspective view from above showing all the components of the device as illustrated in Figures 1 to 4; Figure 6 a perspective view from below of the components illustrated in Figure 5; and

Figure 7 on an enlarged scale, an exploded sectional side view of the bearing components of the device as illustrated in Figures 1 to 6.

DETAILED DESCRIPTION OF DRAWINGS Referring to the drawings, the rotatable balancing platform device in accordance with the invention, generally indicated by reference numeral 10, includes a bottom disc 12, a platform or top disc 14 rotatably mounted on the bottom disc 12 by way of a shaft 16 fitted into a sealed bearing 18 and a thrust bearing 20 fitted between the bottom disc 12 and the top disc 14, the shaft 16 having an internally threaded cylinder 22 into which cylinder a threaded bolt 24 is screwable, and optionally a handle 26 removably attachable to the upper disc 14 (Details of the various bearing components will be given hereinafter when describing the components illustrated in Figure 7).

The lower disc 12 has an annular rim 28 from which there radially extend arms 30 to a central hub 32.

As can be seen in particular in Figures 1,3, 4,5 and 6 the rim 28 of the bottom disc 12 is constituted by an upper rim part 34, which has a uniform height"H1"and integrally formed therewith a bottom rim part <BR> <BR> 36, which in side view is wedge shaped so that it extends from a height "H2"down to substantially zero (0). Thus the disc 12 is slanted when positioned on a support surface 38. Thereby the hub 32 and therewith the threaded cylinder 22 in the top disc 14 are also inclined to the horizontal and the rotational axis 40 passing therethrough is at an inclination to the

vertical axis 42 defining an angle oc between them (see Figure 3). This angle oc can be between 2° and 10°, preferably 1, 75°.

The upper disc 14 includes an annular rim 44 from which there extend radial arms 46 to a central hub 48. The shaft 16 extends from the central hub 48 and it has a hole 50 in which the internally threaded cylinder 22 is embedded. The shaft 16 has a stepped shoulder 52.

The annular rim 44 has a uniform height"H3".

The lower disc 12 has a plate disc 54 from which the rim 28 depends downwardly, and the upper disc 14 has a support platform 56 from which the rim 44 depends.

For small children it is advisable to provide a handle 26 for them to hold on to prevent falling off the disc 14. This handle 26 has a gripping part 58 joined to a rod 60 carrying at its free end a hook 62. The hook 62 has a lower gripping part 64 adapted to grip from below onto the rim 44 and an upper gripping part 66 to grip onto the platform 56 of the disc 14. The handle 26 can be clipped on or removed as required.

Referring to Figure 7 the bearing components, shown in exploded sectional side view, will now be described.

From the hub 48 of the disc 14 the downwardly directed shaft 16 extends in which shaft 16 the hole 50 with the embedded internally threaded cylinder 16 is provided. The shaft 16 has stepped shoulders 52 and 68 and is surrounded by an annular recess 70. The hub 48 includes an annular groove 72 facing towards the bottom disc 12.

The bottom disc 12 has, on its plate disc 54, an upwardly directed annular ridge 74 and a central recess 76. A disc shaped recess 78 is provided centrally in the plate disc 54 and it has a central hole 80 in a plate 82. An annular ring 84 extends downwardly from the plate 82 and defines a recess 86. The hub 32 is arranged concentrically to the ring 84.

The thrust ball bearing 20 includes an annular ball bearing cage 88 in which a number of circumferentially distributed balls 90 are rotatably mounted. When assembled, the balls 90 run in the upper grooved plate 92 fitted into the recess 72 and the lower grooved plate 94 fitted into the recess 78.

The sealed bearing 18 includes an outer ring 96 and an inner ring 98 rotatbly mounted by way of bearing elements 100 (not shown in detail) located between the outer ring 96 and the inner ring 98. A central hole 102 exists in the inner ring 98.

When assembled the upper grooved plate 92 fits into the recess 72, the balls 90 run in the grooved plate 92 and also in the lower grooved plate 94 fitted into the recess 78. The bearing 18 fits into the recess 86. The shaft 16 extends into the hole 102 and the threaded bolt 24 is screwed by way of its threaded shank 104 into the internally threaded cylinder 22 with the washer 106 positioned between the bottom face of the ring 98 and the head 108 of the threaded bolt 24.

By way of the bearings 18 and 20 vertical forces caused by a person standing on the platform 56 are taken up whilst rotation about the rotational axis 40 is allowed.

The discs 12 and 14 and the handle 26 are injection moulded of suitable plastics material. One example of plastics material is a mixture of glass fibre and Nylon material, e. g. in a proportion of about 30 % glass fibre, reinforced modified flow grade and 70 % poly (hexamethylene adipamide).

The radial arms 30, 46 strengthen the disc 12,14 and also provide a light weight construction with a resultant saving in material used. This results in a cost-saving, economic but overall strong and robust construction.

The internally threaded cylinder 16, the bearings 18 and 20 and the threaded bolt 24 with its washer 106 are made of suitable metal.

In the assembled condition a person can stand (or sit) on the support platform 56 and by swaying his body can cause the disc 14 to rotate relative to the bottom disc 12. Due to the inclined axis of rotation 40 the person will be moved continuously between a lower position on the left hand side shown in Figure 3 and a higher position on the right hand side.

This will cause an imbalance which has to be balanced out by suitable movement of the body of a person. The faster the disc 14 is rotated the more difficult it becomes to correct the imbalance occurring.

Reference numerals 10 rotatable balancing platform device 12 bottom disc 14 top disc 16 shaft 18 bearing 20 bearing 22 internally threaded cylinder 24 threaded bolt 26 handle 28 annular rim 30 radial arms 32 central hub 34 upper rim part 36 bottom rim part 38 support surface 40 rotational axis 42 vertical axis 44 annular rim 46 radial arms 48 central hub 50 hole 52 stepped shoulder 54 plate disc 56 support platform 58 gripping part 60 rod 62 hook 64 lower gripping part

66 upper gripping part 68 stepped shoulder 70 annular recess 72 annular groove 74 annular ridge 76 central recess 78 disc shaped recess 80 central hole 82 plate 84 annular ring 86 recess 88 annular ball bearing cage 90 balls 92 upper grooved plate 94 lower grooved plate 96 outer ring 98 inner ring 100 bearing elements 102 central hole 104 threaded shank 106 washer 108 head