Abstract
There is disclosed apparatus (100) for weighing a person with reduced mobility, the apparatus (100) comprising: a seat portion (102); scales (104) for weighing the person when sitting on the seat portion; and a lifting mechanism (106) to assist the person in standing up from the seat portion (102).
Claims
1. An apparatus for weighing a person with reduced mobility, the apparatus comprising: a seat portion; scales for weighing the person when sitting on the seat portion; and a lifting mechanism to assist the person in standing up from the seat portion, wherein the lifting mechanism is operable to move the seat portion between: a sitting position, for engaging with the person in a sitting position, and a standing position, for engaging with the person in a standing position, wherein, in the sitting position, the seat portion contacts the scales and does not contact the lifting mechanism.
2. The apparatus according to claim 1, wherein the lifting mechanism acts on the seat portion and the seat portion urges the person to a standing position.
3. The apparatus according to claim 2, wherein the lifting mechanism is operable to move the centre of gravity of the seat portion in an upwards direction.
4. The apparatus according to claim 2, wherein the lifting mechanism is operable to rotate the seat portion so as to raise the rear of the seat portion relative to the front of the seat portion.
5. The apparatus according to claim 1, wherein the lifting mechanism is operable in reverse to assist the person in sitting down on the seat portion.
6. The apparatus according to claim 1, wherein, in the standing position, the seat portion contacts the lifting mechanism.
7. The apparatus according to claim 1, wherein the seat portion has a first range of movement from the standing position to the sitting position, the lifting mechanism has a second range of movement from the standing position to the sitting position, and the second range of movement is greater than the first, such that when the seat portion reaches the end of its movement and comes to rest on the scales, the lifting mechanism is operable to continue its movement into clearance of the seat portion.
8. The apparatus according to claim 1, wherein the lifting mechanism comprises a lifting member which engages with the seat portion at an engagement region, and wherein the apparatus further comprises at least one actuator guide for restraining the lifting member at the end of a movement of the seat portion to the sitting position.
9. The apparatus according to claim 8, wherein the seat portion rotates about a seat pivot axis between a first angle corresponding to the sitting position and a second angle corresponding to the standing position, and wherein the lifting member is a linearly extendable member, such that reciprocating motion of the extendable member is converted into a rotation of the seat portion about the seat pivot axis.
10. The apparatus according to claim 8, wherein the lifting member is constrained within an aperture in an actuator link plate attached to the seat portion, the aperture defining a linear freedom of movement of the seat portion relative to the lifting member.
11. The apparatus according to claim 10, wherein the aperture is shaped such that rotation of the lifting member relative to the seat portion causes the lifting member to be constrained by different parts of the aperture.
12. The apparatus according to claim 11, wherein different parts of the aperture permit different degrees of freedom of the seat portion relative to the lifting member.
13. The apparatus according to any claim 1, wherein the person can be moved into position on the seat portion from at least one side of the apparatus as well as from the front.
14. The apparatus according to claim 1, further comprising at least one rest selected from: a back rest, at least one foot rest, and at least one arm rest.
15. The apparatus according to claim 14, wherein said at least one rest is moveable between a deployed position and a stowed position, wherein when said at least one rest is in the stowed position, unobstructed access is provided to the seat portion from the front and from at least one side of the apparatus.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:
[0030] FIG. 1 is a schematic of an apparatus for weighing a person with reduced mobility;
[0031] FIGS. 2A and 2B are schematics showing the seat portion of the apparatus of FIG. 1 in a sitting position and in a standing position;
[0032] FIG. 3 is a schematic showing the connection of a linearly extending lifting member with the seat portion of the apparatus of FIG. 1;
[0033] FIG. 4 is a diagram showing a triangle defined by the arrangement of pivot points X, Y and Z shown in FIG. 3;
[0034] FIG. 5 is a schematic of a practical embodiment of the apparatus of FIG. 1;
[0035] FIGS. 6A and 6B are schematics showing the engagement of the linearly extending lifting member of FIG. 3 within an aperture of a connecting plate attached to the seat portion, shown in the sitting position and in the standing position;
[0036] FIGS. 7A and 7B are front and side views of an arrangement including the connecting plate of FIGS. 6A and 6B and two actuator guides;
[0037] FIGS. 8A to 8C are schematics showing three stages of relative movement and engagement between the aperture and transverse bar shown in FIGS. 7A and 7B;
[0038] FIGS. 9A and 9B are schematics of a further embodiment, showing the engagement of the linearly extending lifting member of FIG. 3 within an aperture of a connecting plate attached to the seat portion, shown in the sitting position and in the standing position;
[0039] FIG. 10 shows an aperture suitable for use in the apparatus of FIGS. 9A and 9B;
[0040] FIGS. 11A to 11D show detailed dimensions of a connecting plate including an aperture suitable for use in the apparatus of FIGS. 9A and 9B;
[0041] FIGS. 12A to 12D are schematics showing four stages of relative movement and engagement between the aperture of FIG. 10 and a transverse bar driven by a lifting member;
[0042] FIGS. 13A and 13B are perspective views of an example weighing chair embodying the apparatus of FIG. 1; and
[0043] FIGS. 14A and 14B are perspective views of the weighing chair of FIGS. 13A and 13B with the seat in a sitting position and in a standing position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0044] The preferred embodiment provides an apparatus (typically a weighing chair) for weighing people with reduced mobility. Various aspects and features of the apparatus will now be described.
[0045] FIG. 1 is a schematic of an apparatus for weighing a person with reduced mobility. This apparatus has broad applicability and may or may not be in the form of a chair. The apparatus 100 includes a seat portion 102 (for receiving the person), a set of scales 104 (for weighing the person) and a lifting mechanism 106 (for assisting the person in standing up from the apparatus).
[0046] FIGS. 2A and 2B are schematics showing the seat portion of the apparatus of FIG. 1 in a sitting position and in a standing position. These figures are a side view. In use, the person would sit on the seat portion with legs positioned at the right of the figure. The pictured apparatus 200 includes the seat portion 202 as before, the scales 204, a pivot point 206 or hinge attaching the seat portion 202 to the apparatus 200. While in the sitting position, a small amount of unrestricted and unsupported movement 208 is possible in a vertical direction, allowing the person sitting on the seat portion 202 to be weighed accurately. At the time of weighing, the seat portion 202 is supported solely by the scales 204. The scales 204 includes at least one load cell. In one variant, the seat portion 202 is supported by a load cell at each corner, and the outputs of all the load cells are summed to provide a measure of the applied weight.
[0047] Other arrangements are of course possible. For example, the pivot point 206 may be connected to or via the load cell(s) directly, or the lifting mechanism may be configured such that the pivot point 206 is only a virtual pivot, and the seat portion 202 does not physically connect to it.
[0048] FIG. 3 is a schematic showing the connection of a linearly extending lifting member with the seat portion of the apparatus of FIG. 1. The apparatus 300 includes the seat portion 302 as before, and a pivot point (X) 304 attaching the seat portion 302 to the apparatus 300. As noted above, point (X) 304 may be a virtual pivot point in the sense that the seat portion 302 does not physically connect to it, or to the apparatus (except via the scales, not shown). A linearly extending member 306 connects to the seat portion 302 at the pivot point (Y) 308. As with point (X) 304, point 308 can be a virtual pivot point in the sense that the member 306 rotates about it but does not physically connect to it, but in the main embodiment it is effectively a normal pivot point.
[0049] FIG. 4 is a diagram showing a triangle defined by the arrangement of pivot points X, Y and Z shown in FIG. 3. Lengths L.sub.1 and L.sub.3 are fixed and measurable/predetermined. Length L.sub.2 varies as the extending member 306 of FIG. 3 is extended or retracted. Angles .sub.1, .sub.2 and .sub.3 vary as the extending member 306 is extended or retracted, causing a change in rotation of the seat member and a transition to/from the sitting and standing positions.
[0050] The law of cosines (c.sup.2=a.sup.2+b.sup.22ab cos C) can be used in conjunction with a sensed or known extension of the linearly extending member 306, or the law of sines (sin(A)/a=sin(B)/b=sin(C)/c) can be used in conjunction with any measured or known angle .sub.n, to determine all remaining angles. This can be used in particular to determine the angle .sub.3 for each moment as the seat portion moves from sitting to standing position (which transition can be expressed with the ranges L.sub.SITTING<L.sub.2<L.sub.STANDING, or .sub.SITTING<.sub.2<.sub.STANDING).
[0051] Notwithstanding the above, the key point is that angle .sub.3 subtended between the linearly extending member 306 and the seat portion 302 varies predictably as the seat portion transitions between sitting and standing positions (and vice versa). Angles .sub.1 and .sub.2 also varies predictably as the seat portion transitions between positions.
[0052] FIG. 5 is a schematic of a practical embodiment of the apparatus of FIG. 1. A weighing chair 500 is shown, including a seat portion 502, a lower seat portion 504 fixed to the rest of the apparatus, a pivot point 506 where the seat portion 502 rotates relative to the lower seat portion 504. The chair 500 further includes a back rest portion 508, a lower support 510, a bottom base 512, wheels 514, an actuator of an appropriate type 516, the pivot point 518 where the actuator 516 rotates relative to the seat portion 502, and finally the scales 520 for measuring the weight of a person sitting on the seat portion 502 when it is in the sitting position (as shown). A power and/or control system 522 provides power to the actuator 516, and can be controlled by a control panel (not shown) which can be attached in any appropriate place on the chair.
[0053] The term actuator is used in a general sense to connote any device capable of applying a force or causing movement on demand, and may, for example, include devices capable of applying a torque or causing a rotation. The actuator 516 may nevertheless comprise an actuator within the narrow sense of the term in the field of mechanical engineering. The actuator 516 may alternatively or additionally include a piston arrangement, gas strut (with appropriate preloading), electric motor with appropriate gearing and translation from rotational to linear movement as necessary, magnetic actuation, pneumatic or hydraulic mechanisms as appropriate for any given application.
[0054] Preferably a strain (or other) load cell is used as the scales (that is, simply to weigh the person). Appropriate zeroing and/or calibration may be provided, for example periodically to weigh the seat portion without a person sat on it (either manually or automatically). Other types of scales are of course possible, including devices based on magnetic, inductive, mechanical, optical, or piezoelectric principles, and so on.
[0055] FIGS. 6A and 6B are schematics showing the engagement of the linearly extending lifting member of FIG. 3 within an aperture of a connecting plate attached to the seat portion, shown in the sitting position and in the standing position. The arrangement 600 includes a seat portion 602 as above, the seat portion pivot point 604, a connecting plate 606 attached to the seat portion 602, an aperture 608 within the plate 606, an actuator or similar 610, an actuator pivot point 612, a linearly extending member 614, and a rod 616 extending transversely through the aperture 608 and fixed to the distal end of the linearly extending member 614.
[0056] In the present embodiment two separate connecting plates 606 are provided with two separate but matching apertures 608, and the rod 616 passes transversely between both, threading through a hole in the distal end of the member 614 so as to secure it in place and prevent out of plane rotations (as pictured in FIGS. 6A and 6B) between the actuator and seat portion.
[0057] It will be appreciated the weight from the seat and/or the weight of a user urges the seat 602 and correspondingly the plates 606 onto the transverse bar 616. In the standing position of the seat 602 and when the actuator is retracting the seat towards the sitting position (but not yet fully retracted), the bar 616 forms a pivot at the top of the aperture 608. The shape of the top of the aperture permits the bar 616 to roll freely without causing any displacement between actuator 610 and seat 602. When the actuator 610 comes to the end of its travel, the transverse bar 616 moves into clearance from the aperture 608 and consequently seat 602, as is described below.
[0058] FIGS. 7A and 7B are front and side views of an arrangement including the connecting plate of FIGS. 6A and 6B and two actuator guides. The two actuator link plates 702 are shown, including the respective apertures 704. The transverse bar 706 is shown in place, controlled by the linearly extending member 708 (with only the distal part shown for clarity). A set of scales (load cell) 710 is shown diagrammatically, ready to receive the full weight of the seat (not shown) and occupant (not shown). Two actuator guides 712 are shown, with receiving surfaces 714 for receiving the transverse bar 706. As the actuator retracts the linearly extending member 708 to the end of its range, the transverse bar 706 is caused to engage with the actuator guides 712. The set of scales 710 is positioned appropriately and/or yields enough that the weight of the seat and occupant (not shown) is sufficient to cause the seat and consequently actuator plate 702 to proceed downwards to a position where the bar 706 is engaged with the actuator guides in clearance of the sides of the aperture 704, and the set of scales is in sole (upwards) contact with the seat and occupant, and is not in communication with the actuator, linearly extending member, or bar 706.
[0059] FIGS. 8A to 8C are schematics showing three stages of relative movement and engagement between the aperture and transverse bar shown in FIGS. 7A and 7B. This is a more visual demonstration of the process described above.
[0060] In FIG. 8A, the seat is in (or near) the standing position. The bar, aperture and part of the seat are shown. The actuator link plate (not shown) which contains the aperture is mounted in a fixed location and angle to the seat (and is typically mounted at an angle appropriate for the geometry of the seat, plate and actuator arrangement). The transverse bar is nestled in the top of the aperture where it is free to roll.
[0061] In FIG. 8B, the seat (in part), bar, aperture and actuator guide are shown. The seat has just reached the sitting position and is about to come into contact with the scales (not shown). The weight of the seat and occupant still acts on the transverse bar, pinning it into the top of the aperture.
[0062] In FIG. 8C, the seat (in part), bar, aperture and actuator guide are again shown. The seat has come into contact with the scales (not shown), which now provides a reaction force against the weight of the seat and occupant. The bar continues to move downwards under the operation of the actuator (not shown), and comes to rest on the actuator guide. In this final position, the sitting position, the bar (and consequently the linearly extending member and actuator mechanism, not shown) is in clearance of the aperture and consequently the seat and occupant. The scales (not shown) are thus able to weight the occupant without any interference from any other part of the apparatus.
[0063] Thus a mechanism is provided which can engage and disengage a lifting mechanism with a seat portion (or other appropriate drive object) merely by extending and retracting a member. This can provide a relatively low cost system for weighing a person with reduced mobility.
[0064] FIGS. 9A and 9B are schematics of an alternative embodiment, having a different shape of actuator link which allows the degrees of freedom of the seat portion to be controlled in dependence on the position of the seat. FIGS. 9A and 9B in particular show the engagement of the linearly extending lifting member of FIG. 3 within an aperture of a connecting plate attached to the seat portion, shown in the sitting position and in the standing position. The arrangement 900 includes a seat portion 902 as above, the seat portion pivot point 904, a connecting plate 906 attached to the seat portion 902, an aperture 908 within the plate 906, an actuator or similar 910, an actuator pivot point 912, a linearly extending member 914, and a rod 916 extending transversely through the aperture 908 and fixed to the distal end of the linearly extending member 914. The virtual pivot point 918 is shown, corresponding to the centre of relative rotation between the seat portion 902 and the extending member 914.
[0065] In the present embodiment two separate connecting plates 906 are provided with two separate but matching apertures 908, and the rod 916 passes transversely between both, threading through a hole in the distal end of the member 914 so as to secure it in place and prevent out of plane rotations (as pictured in FIGS. 9A and 9B) between the actuator and seat portion.
[0066] It will be appreciated from FIGS. 9A and 9B that the rod 916 moves across the aperture as the seat position changes. This basic design can allow different freedom of movement to be provided at different positions of the seat portion 902 as the rod contacts different parts of the aperture. An example aperture design will now be described.
[0067] FIG. 10 shows an aperture suitable for use in the apparatus of FIGS. 9A and 9B. The aperture 1000 is shown in thick lines. Also indicated on the figure are circles, representing different radial distances r.sub.1, r.sub.2, r.sub.3 from the pivot point, and lines radiating out from the pivot point, representing different alignments of the rod and extending member (not shown) with the aperture at different points in the transition between sitting and standing positions of the seat portion. In this case, angle .sub.1 (no connection to the angles shown in FIG. 4) represents the angle subtended between the extending member and the seat portion when the seat portion is in the standing position (elevated/rotated). Angle .sub.3 represents the angle subtended when the seat portion is in the sitting position (horizontal/flat and ready for weighing). Angle .sub.2 represents a transition point between a region to the right where the aperture constraints the rod tightly, preventing any free movement of the seat, and a region to the left where the rod is free to move up and down, meaning that the seat portion is not tightly engaged with the extending member at that point.
[0068] In the expanded region, there is a dead zone or hysteresis, where the rod attached to the extending member can be moved into the middle of the aperture and thereby avoid all contact with the aperture or, by extension, the seat portion. As before, this can allow weighing without any external influence from the lifting mechanism. More generally, this mechanism can provide a way to vary the freedom of movement of the seat portion in dependence on its rotation without any complicated extra components to allow such a decoupling (or indeed any extra components whatsoever).
[0069] FIGS. 11A to 11D show detailed dimensions of a connecting plate including an aperture suitable for use in the apparatus of FIGS. 9A and 9B. The dimensions are marked on in millimetres. This detailed embodiment has extra features for improved performance, such as smooth transitions in the aperture surface and a central hole for attaching to the seat portion (with a cut-out part to receive a wedge to prevent rotation of the plate relative to the seat portion). With the smooth curves, the interior surface of the connector plate behaves essentially like a cam surface, and the rod attached to the extending member behaves essentially like a cam follower, although in fact the rod drives the connector plate. Various techniques in the field of cams and followers which improve contact and efficiency between the cam surface and follower and/or which reduce wear can be applied to the present apparatus as appropriate.
[0070] FIGS. 12A to 12D are schematics showing four stages of relative movement and engagement between the aperture of FIG. 10 and a transverse bar driven by a lifting member. This is a more visual demonstration of the process described above. In FIG. 12A, the rod is at the furthest extent to the right of the aperture as the seat portion (not shown) is in the standing position. The extending member (and consequently the rod) is retracted, causing the rod to push down on the lower aperture surface as indicated. In FIG. 12B, the downward movement of the extending member and the seat portion has caused the rod to shift leftwards in the aperture. In FIG. 12C, the movement towards the sitting position has completed, and the rod exerts a downward force against the lower surface of the aperture as shown. In FIG. 12D, the extending rod is given an (optional) small extension to take it out of contact entirely with the aperture. Thus an alternative mechanism is provided which can engage and disengage a lifting mechanism with a seat portion (or other appropriate drive object) merely by extending and retracting a member. This can provide a relatively low cost system for weighing a person with reduced mobility.
[0071] FIGS. 13A and 13B are perspective views of an example weighing chair embodying the apparatus of FIG. 1. Here a fully worked example of the chair is given, based on the chair shown in FIG. 5. Both the arm rests and the foot rests are retractable. The foot rests retract sideways, providing ample room for the person to stand up when the seat portion is lifted up as described above. In the preferred embodiment the foot rests rotate at least 180 degrees so that both the front and side of the weighing chair are unobstructed, and (separately, optionally) the arm rests retract beyond and behind their pivot point such that they too do not obstruct either the front or sides of the chair. Horizontal, vertical or other pivot points can be used, and in some cases two sets of pivots/movements (that is, at least two degrees of freedom) can be provided, for example in relation to the foot rests, so as to permit them to be moved substantially completely out of the way. This can allow an occupant to be moved into the chair from either the front or from either side, and from a wheelchair or similar apparatus without significant obstruction, for example.
[0072] Brakes may be provided and applied to the wheels as appropriate. A hollow in the back rest provides appropriate cable management within easy reach, and a control panel allows both weighing operations and activation of the lifting mechanism. Other arrangements are of course possible.
[0073] FIGS. 14A and 14B are perspective views of the weighing chair of FIGS. 13A and 13B with the seat in a sitting position and in a standing position. Smaller or larger rotations of the seat portion are possible, and other configurations of the chair are possible as necessary and/or appropriate.
[0074] Various features have been described above in relation to a weighing chair, but variants are possible in which the operative elements described above are provided in alternative forms. Appropriate modifications may be made for example to incorporate the above-mentioned features into a hospital bed (in-patient or out-patient), into an otherwise ordinary chair, sofa or bed, and so on. The relevant object may be mobile (for example have wheels) or not, and may for example be suspended from a ceiling rather than stand on the floor. The concepts described herein can of course also be used to weigh things rather than people, or for any other appropriate purpose.
[0075] It will be appreciated that further modifications may be made to the invention, where appropriate, within the spirit and scope of the claims.
