Australian patent 639,124 in the name of D. F.

Wrigley and F. S. Saberton discloses a height-adjustable bed that has a general application for use by handicapped and elderly people, and it is designed particularly for use in geriatric wards in hospitals and in nursing homes.

The bed disclosed in patent 639,124 comprises a pair of bed ends and a mattress platform which includes a frame supported on two beams. The mattress platform is suspended from the bed ends by a pair of chains associated with each beam. The chains pass over and under associated pairs of sprocket wheels mounted on the beams. The ends of the chains are connected to associated upper and lower mounting points on the bed ends. One of the pairs of sprocket wheels is mounted on a shaft which rotates with the sprocket wheels. A tension spring associated with one of the beams has one end connected to the beam and the other end connected to a wire which is wound around a fusee that is also mounted fixedly on the shaft. As the mattress platform is lowered, rotation of the shaft causes the wire to be wound on to the fusee, thus increasing the tension in the spring and providing a lifting bias for the mattress platform. An electric motor mounted on one of the bed ends preferably drives a screw and nut arrangement to raise and lower the mattress support platform.

The bed is a substantial improvement over beds that were in use or otherwise known before the priority date of 20 July 1990 of the patent.

Nevertheless, an object of the present invention is to provide a height adjustable bed which is an

improvement over the bed disclosed in patent 639,124.

According to the present invention there is provided a height adjustable bed which includes: (a) a mattress platform for supporting a mattress and a person; (b) a first bed end and a second bed end at opposite ends of the mattress platform for supporting the mattress platform and the person when on the mattress platform, each bed end including a guide means for guiding the mattress platform between lower and raised positions, and the bed ends being foldable from: (i) an operational position in which the bed ends are upright and can support the mattress platform and can guide the mattress platform between the lower and raised positions; and (ii) a transport position in which the bed ends are folded down and overlie the mattress platform.

When the above-described bed is in the folded down transport position it forms a compact unit that can be efficiently and securely transported by way of example from a manufacturing site to an end use location. Moreover, the above-described bed can be folded down into the transport position and later re-erected to the operational position with minimal effort and in a short period of time in situations where a fully erected bed could not be located.

Preferably the bed includes a drive means for

moving the mattress platform between the lowered and raised positions.

Preferably the bed includes a releasable locking means for locking the bed in the operational position.

Preferably the bed includes a means for suspending the mattress platform from the bed ends.

Preferably the suspension means includes: (a) a plurality of sprocket wheels mounted to end sections of the mattress platform for rotation about horizontal axes; (b) at least one first chain mounted to an upper mounting point of the first bed end and extending downwardly and under one sprocket wheel at that bed end and across to the second bed end and over one sprocket wheel at that bed end and downwardly to a lower mounting point of the second bed end and attached to the lower mounting point; and (c) at least one second chain mounted to a lower mounting point of the first bed end and extending upwardly and over one sprocket wheel at that bed end and across to the second bed end and under one sprocket wheel at that bed end and upwardly to an upper mounting point of the second bed end and attached to the upper mounting point.

Preferably the suspension means includes two first chains and two second chains.

Preferably the mattress platform includes a main

section and end sections which are pivotally connected to opposite ends of the main section and carry the sprocket wheels, whereby each bed end and associated end section are foldable as a unit about the pivot connection with the main section from the operational position to the transport position.

With this arrangement, the sprocket wheels are retained with the bed ends and move relative to the main section of the mattress platform when the bed ends and associated end sections of the mattress platform fold into the transport position.

Preferably the mattress platform includes a means for maintaining tension of the first and second chains as the bed ends and end sections of the mattress platform are folded from the operational position to the transport position. This is an important feature since it ensures that the chains remain on the sprocket wheels.

Preferably the means for maintaining tension include reaction surfaces that contact and maintain the tension of the first and second chains as the bed ends and end sections of the mattress platform are folded from the operational position to the transport position.

The present invention is described further with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a preferred embodiment of a height adjustable bed in accordance with the present invention; Figure 2 is a perspective view of part of the mattress platform and one bed end of the bed shown in Figure 1;

Figure 3 is a section along the line 3-3 in Figure 2; and Figure 4 is a section along the line 4-4 in Figure 2 after the bed end has been folded from an operational position shown in Figures 1-3 to a transport position as shown in Figure 4.

The basic construction of the bed shown in the Figures is similar in many respects to that of the preferred embodiment of the bed shown in Australian patent 639,124 mentioned above and to the preferred embodiments of the bed disclosed in International patent application PCT/AU97/00767 in the name of Gerontic & General Products Pty Ltd. The disclosure in the Australian patent and the International application are incorporated herein by cross- reference. In basic terms, the bed includes: (i) a mattress platform; (ii) two bed ends at opposite ends of the mattress platform; (iii) a means for suspending the mattress platform from the bed ends; and (iv) a drive means for raising and lowering the mattress platform.

With reference to the figures generally, the bed ends, namely a head end 41 and a base end 43, are formed from steel and each bed end comprises an end wall 47 and sides 49.

The mattress platform includes: (i) a support assembly of two spaced-apart

elongate beams 11 and cross-members 13 which interconnect the beams; and (ii) a mattress support frame 10 which rests on and is supported by the support assembly.

The frame 10 is formed in two parts 12,19 which are hinged together by hinge members (not shown), with the part 12 forming a back rest section which can be raised relative to the other part 19 from a horizontal position to a series of raised positions.

The mattress platform further includes a means (not shown) for raising/lowering the back rest section 12 and for raising/lowering the frame 10 into a Trendelenberg position in which the legs and body of a person on the bed are raised relative to the head of the person.

The suspension system of the bed enables the mattress platform to be raised and lowered through a range of positions from the dashed outline lowered position to the solid outline raised position shown in Figure 1.

The preferred embodiment of the suspension system is based on the use of: (i) two pairs of chains; and (ii) sprocket wheels 33 mounted to each end of the mattress platform for rotation about horizontal axes.

One pair of chains and one of the sprocket wheels 33 at the head end 41 of the bed are shown in Figures 3 and 4.

With reference to Figures 3 and 4, a first chain

45 of each pair is attached to an upper mounting point (not shown) of the head end 41 and extends downwardly and under a sprocket wheel 33 and along the length of the beam 11 and over a sprocket wheel 33 (not shown) at the opposite end of the beam 11 and downwardly to a lower mounting point (not shown) of the base end 43 and is attached to that mounting point.

With further reference to Figures 3 and 4, a second chain 47 of each pair is attached to a lower mounting point (not shown) of the head end 41 and extends upwardly and over the sprocket wheel 33 and along the length of the beam 11 and under the sprocket wheel 33 (not shown) at the opposite end of the beam 11 and upwardly to an upper mounting point (not shown) of the base end 43 and is attached to that mounting point.

With reference to Figure 2, the drive means for moving the mattress platform includes an electric motor (not shown) mounted on the head end 41 of the bed. The motor drives a vertically-extending screw 45 which extends through and threadedly engages a nut 46 connected to cross- member 13 of the mattress platform. With this arrangement, rotation of the screw 45 about its vertical axis causes vertical movement of the mattress platform via the nut 46.

Each bed includes a guide assembly at each bed end 41,43 for ensuring smooth vertical movement of the mattress platform when the drive means is actuated.

With reference to Figure 2, the guide assembly comprises a vertical rail 61 connected to each side 49 of the bed ends 41,43 and a guide carriage 63 connected to the ends of the elongate beams 11 of the support assembly of the mattress platform. The carriages 63 are constructed with rollers (not shown) for sliding movement along the rails 61.

With reference to Figures 2 to 4, each beam 11 of the support assembly of the mattress platform includes a main beam section 25 and end sections, generally identified by the numeral 27. As is described in more detail below, the end sections 27 and the main beam section 25 are pivotally connected together.

Each end section 27 includes parallel side walls 29 that are welded to both the lower and the upper cross- members 13 shown in the figures. A pivot pin 35 extends between and is supported by the side walls 29. In addition, one of the sprocket wheels 33 is mounted to and supported by the side walls 29 of the end section 27.

Each end of the main beam section 25 includes a side 31 that extends parallel to and inwardly of one of the side walls 29 of the adjacent end section 27. The side 31 includes an opening (not shown) and the side 31 is positioned so that the pivot pin 35 extends through the opening. This arrangement pivotally connects together the end section 27 and the main beam section 25.

It can readily be appreciated that with the above described arrangement the bed ends 41,43 and the end sections 27 (including the sprocket wheels 33) are linked together in the sense that each bed end 41,43 and associated end sections 27 are constrained to pivot together as a unit relative to the main beam section 25 between the operational position shown in Figure 3 and the transport position shown in Figure 4.

The bed also includes reaction surfaces that contact the chains 45,47 as the bed ends 41,43 and associated end sections 27 are being folded from the operational position to the transport position and maintain the tension of the chains 45,47. The reaction surfaces

include an outer sleeve 71 of each pivot pin 35 which is positioned to contact the first chain 45 and an extension 73 of the top wall of the main beam section 25 which is positioned to contact the second chain 47 during pivoting movement of the bed ends 41,43 and associated end sections 27 onto the mattress platform.

The bed also includes an assembly for locking together the main beam section 25 and each end section 27 when the bed ends 41,43 are in the operational position.

Each locking pin assembly includes a locking pin 77 that can be positioned in openings 79 in the side 31 of the main beam section 25 and the adjacent side wall 29 of the end section 27 which are aligned when the bed ends 41,43 are in the operational position.

The above described bed has a number of considerable safety and performance advantages over conventional beds.

Many modifications may be made to the preferred embodiments of the present invention described above without departing from the spirit and scope of the present invention.