BACKGROUND OF THE INVENTION Hammocks are very popular throughout the world. People enjoy hammocks as they are able to lie comfortably in a hammock and swing. However, it takes considerable amount of practice to get into and out of a hammock and people often fall when attempting this. Whilst in the hammock, it is very easy to roll incorrectly and overbalance the hammock causing a person fall from the hammock. Also, it is almost impossible to sit upright in a hammock without falling. As hammocks are suspended above the ground, any fall from a hammock can cause serious injury to a user.

A hanging chair was developed in an attempt to allow people to be suspended above the ground and sit upright. The hanging chair is a semi-spherical chair that is suspended by a chain at its top. As the chair is only suspended at a single point, often unwanted rotation of the chair occurs.

A person also cannot lie down in the chair.

To enable a person to utilise both a reclining and sitting position, a reclining chair was developed. The reclining chair can be moved from a sitting position to a reclining position and visa-versa by a lever located on a side of the chair or by pushing or pulling armrests located on the chair.

The problem with this chair is considerable force is needed to move the chair between the two positions. Also, after the initial resistance of the movement is overcome by applying sufficient force, considerable less force is required to continue the movement causing the chair to be jerked between the positions which is undesirable.

An example of such a reclining chair is disclosed in International Patent Application No. WO 97/38608. This chair has a support platform that is connected to a pair of swing links that enable the support

platform to moved between an upright and reclined position. This swing mechanism has a complex operation as the support platform pivots about both the swing links. It is also expensive to manufacture.

US Patent No. 4,341,420 discloses a further reclining chair.

This chair has a support platform is formed from a number of beams that move relative to one another when the chair is moved from a reclined position to an upright position. An articulated parallelogram linkage suspends the support platform for movement between the reclined position and the upright position. This chair is complex in operation as both the support member and the parallelogram linkage move when the chair is moved from the reclined position to the upright position. Specifically, the support member has a complex scissoring movement. Further, there is likely to be a jerked movement of the support platform when moving between respective positions. Still further, due to the complex operational of the chair, the chair is expensive to manufacture.

US Patent No. 6,206,472 shows a reclining chairthat is formed from a support platform that is attached to a number of legs. The chair pivots about one of these legs and can be moved from a reclined position to a upright positioned by an occupant moving their body backward or forward to change the centre of gravity. However, in use, when the chair is moved between positions the support platform falls rapidly until the chair contacts the ground. A rapid deceleration then occurs which is undesirable.

OBJECT OF THE INVENTION It is therefore an object of this invention to overcome at least one or more of the above disadvantages or provide the consumer with a useful or commercial choice.

SUMMARY OF THE INVENTION Accordingly, in one form the invention resides in a chair comprising: a support platform supported for at least limited rotation about a single transverse pivotal axis by support means, the support platform characterised in that it is contoured to constrain a centre of

mass of an occupant to a position closely adjacent said pivotal axis whereby, in use, said support platform is rotatable between a stable upright position and a stable reclined position by moving the centre of mass from one side of an upright plane in which the axis is located to an opposite side thereof.

The support platform may be stabilised by rotation limiting means. A separate rotation limiting means may be associated with each position.

The support platform typically includes a torso supporting region, a buttocks and thigh supporting region and a lower leg supporting region. Usually the angle between the torso supporting region and the buttocks and thigh supporting region, and the angle between the buttocks and thigh supporting region and the lower leg supporting region are obtuse.

The two angles between the associated regions normally are different.

Usually the angle between the torso supporting region and the buttocks and thigh supporting region is between 100°and 160°, and the angle between the buttocks and thigh supporting region and the lower leg supporting region is between 95° and 160°.

The support means may be a suspension means. Alternately, the support means may be firm support extending from a base surface.

The pivotal axis can be positioned above, below or through the supporting platform. Preferably, the distance between the pivotal axis and the centre of mass is less than 30 centimeters. More preferably, the distance between the pivotal axis and the centre of mass is less than 15 centimeters.

An occupant may move the support platform between the two positions by applying a force to the suspension means. Alternately, an occupant may move support platform between the two positions by applying a force to an external member that is external of the support platform. Still alternately, an occupant may move the support platform between the two positions by transferal of a movable mass located on the support platform.

Preferably, the mass is slidably mounted on the support platform.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described with reference to the accompanying drawings in which: FIG. 1A is a perspective view of a suspended chair in an upright position according to a first embodiment of the invention; FIG. 1 B is a perspective view of a suspended chair in a reclined position according to a first embodiment of the invention; FIG. 2A is a side view of a suspended chair in an upright position according to FIG. 1A; FIG. 2B is a side view of a suspended chair in a reclined position according to FIG. 1 B ; FIG. 3A is a side view of a chair in an upright position according to a second embodiment of the invention; and FIG. 3B is a side view of a chair in a reclined position according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENT FIGS. 1A and 1B show a suspended chair 10 suspended above a base surface 11. The chair includes a support platform 20 that is suspended by a support line member 30.

The support platform 20 comprises a pair of rigid arms 21 and 22 that are spaced and interconnected by a number of beams (not shown).

A fabric 23 extends over the beams and is connected to each of the arms 21 and 22 in order to support an occupant 12 who sits in the chair 10.

The support line member 30 is pivotally attached to the side of both of the arm members 21 and 22 and is connected to a suspension point 31 located above the support platform 20. The suspension point can be a simple loop, helical spring or the like.

The support platform 20 can pivot about an axis 40 that extends between where the line member 30 is attached to the arm members 21 and 22. The support platform 20 can be rotated about the axis 40 from an upright position, shown in FIGS. 1A and 2A, to a reclined position, shown in FIGS. 1 B and 2B.

A stop line member 32 is attached to one of the beams located at a top of the support platform to provide stability to the support platform 20 when the support platform 20 is in the reclined position. The stop line member 32 prevents over rotation of the support platform 20. The chair abutting against the base surface 11 provides stability of the support platform 20 in the upright position. The stop line member 32 is attached at the suspension point 31 to allow the chair to rotate about the suspension point 31. Alternatively, the stop line member 32 could be attached away from the stop line member 32 to prevent substantial rotation of the chair 10 about the suspension point 31.

The support platform 20 has three regions of support, namely a torso supporting region 41, a buttocks and thigh supporting region 42 and a lower leg supporting region 43. The torso supporting region 41 is connected to the buttocks and thigh supporting region 42 which is also connected to the lower leg supporting region 43. The angle between the torso supporting region 41 and the thigh and buttocks supporting region 42 is approximately 115°. The angle between the buttocks and thigh supporting region 42 and the lower leg supporting region 43 is approximately 130°.

The support platform 20 is contoured in the manner described above to provide comfort and support to an occupant when in both the upright and reclined positions. However, the contour of the support platform 20 also constrains a centre of mass 50, shown in FIGS. 2A and 2B, of an occupant 12 to specific position that is closely adjacent to the axis 40 about which the chair 10 pivots. This allows an occupant to use only a small force to move the support platform 20 from an upright position to a relined position and visa-versa.

The support platform 20 is stable in the upright and the reclined positions as centre of mass 50 is located on a desired side of the axis 40 in each of these positions. The centre of mass 50 provides a downward force that causes the support platform 20 to push against the stop line member 32 in the reclined position and the base surface 11 in the upright position.

The centre of mass 50 is moved relative to the axis 40 by the

occupant applying a force to the support line member 30 causing rotation of the support platform 20. In the current embodiment, the occupant 12 moves from the upright position to the reclined position by pushing against the support line member 30. To move from the reclined position to the upright position the occupant pulls the support line member 30. Only a small force is required as the centre of mass 50 is adjacent to the axis 40 about which the support platform 20 rotates.

FIGS. 3A and 3B illustrate a further embodiment of the invention. Like numerals have been used to represent like components. In this embodiment, the contours of the support platform 20 are virtually the same. However, the support platform 20 is foldable to allow for more compact storage. The cloth and beams have been replaced by a pre-molded plastics structure 25.

The axis 40, in this embodiment, extends along a shaft 45 that extends through the support platform 20. The shaft 45 has stops (not shown) that limit the rotation of the shaft 45 to prevent over rotation of the support platform.

A rigid support 60, located on a base surface 11, supports the support platform 20 adjacent the axis 40 about which the support platform 20 rotates. A handle 61, attached to the rigid support, is provided on both sides of the support platform 20. The height of the handle 61, relative to the occupant 12, can be adjusted by movement up and down the rigid support 60.

This chair 10 operates in essentially the same manner as described previously. The support platform 20 again is specifically designed so that the centre of mass 50 is closely adjacent the axis 40 of rotation of the supporting platform 20. An occupant 12 moves the chair by between the positions by applying a small force to the handle 61.

It will be appreciated that a person skilled in the art would realise that supporting platform can be constructed from any suitable material such as wood, metal or the like. The supporting platform can also be adjustable to cater for persons of differing body shapes and sizes. The

adjustability of the supporting platform will allow for fine turning the position of the centre of mass so as to almost coincide with the axis.

It will be also appreciated that any means may be used to prevent over rotation of the support platform and thus providing stability of the support platform in both the upright and reclined positions.

It will further be appreciated by a person skilled in the art that the suspension means may be rigid and/or flexible and/or resilient or a combination thereof. The suspension means may be attached to a fixed object or frame or the like.

It will still further be appreciated by a person skilled in the art that the firm support may be rigid or resilient. For example, the support may be in the form of a helical spring.

It will still yet be appreciated by a person skilled in the art that the rotation of the support platform can be moved by providing a mass located on the support platform that can be moved from a position on one side of the axis to the other. For example, a slidable mass located on an armrest can be moved to cause rotation of the supporting platform from one position to another.

It will be appreciated that the embodiments described are by way of reference only and that various other changes and modifications may be to made to the embodiments without departing from the spirit or scope of the invention.