AN IMPROVED MECHANISM FOR ELEVATING SEATS

Abstract: A seat pivots about a transverse horizontal axis set back from its forward edge, a footrest means is dependent by suitable linkages or other means from a point or points adjacent to the forward edge of the seat. When the seat is horizontal the footrest is elevated above the floor level; when the seat tilts about its axis the footrest descends to the floor as the rear of the seat rises to assist the user to rise. Motion as above results from one or more of the following: (i) torque from the resultant of the occupant's weight distributed on the seat; (ii) part of the occupant's weight acting on the footrest; (iii) applicable to moving armrests only, net force applied to armrests; (iv) additional input force applied by an attendant. The seat can be equipped with a backrest together with fixed or moving arms. The backrest can optionally be reclined or, according to variant, linked with a legrest or adaption of the footrest which elevates. Alternatively independent leg support mechanisms may be preferred. The mechanism is equally suited to the use with powered actuator means. The entire assembly must necessarily be mounted within a suitable framework which may be static or wheeled, rigid or folding, to serve as a chair, toilet frame, commode, vehicle seat, or any other form of seating. Or, when the ranges of adjustment and movements are sufficient, bed, stretcher and/or stand-up wheelchair.

Description: AN IMPROVED MECHANISM FOR ELEVATING SEATS "Stand-Easy 2" is a mechanism for elevating seats, an improvement on GB patent no. 2266838. It retains the essential feature that power to elevate the seat to assist rising is provided by the weight of the user, in this way no adjustments are needed to suit other users. It assists the transition between sitting and standing (and vice versa) additionally, by variation of posture and/or design parameters resistance to motion can be tailored to enable variants to provide exercise for many muscles in the human body. GB 2266838 describes an articulated body support assembly, comprising essentially a seat, leg support panel and footrest, all hinged together at adjacent edges. In this improvement any or all panels - particularly the leg support panel - may be replaced with link means with or without rigid or flexible coverings. These means together with the footrest, backrest and armrests may also be jointly or separately adjustable to confer additionally elevated leg support and /or reclining feature. This feature may also optionally afford full length support in stretcher/bed form. To facilitate folding or individual use requirements the footrest(s) may be reduced to simple bar structure which may be articulated or rigid. The whole mechanism in whatever form is essentially mounted upon a chassis structure which may constitute a chair (wheeled or static, rigid or folding), toilet frame, commode or alternatively form part of an ambulance or other vehicle for the transport of the infirm. In variants beyond the essential components a backrest with or without attached armrests may be attached on or near the rear of the seat component so as to rise and fall with the seat thereby affording back support and user safety throughout the range of motion. Armrests may be alternatively part of the base frame - in which case they will not move with the seat - or be attached to the seat at points other than those used for backrest attachment. This latter feature enables armrest elevation to differ from backrest elevation. The backrest is preferably, but not essentially, constrained to maintain a near constant attitude to the floor datum throughout its travel while elevating (and lowering), this is achieved by use of RECTIFIED SHEET (RULE 91) appropriate guide means within the framework. By way of illustration suitable guide means are parallel linkages or guided sliders. Chairs in which the seat and, in some instance, other parts rotate, rise and tilt to assist impaired mobility are well known; many are powered by electric actuators requiring trailing cables etc, others utilise spring means which require adjustment to suit user weight variations. Stand-Easy differs from these in requiring no external power source or adjustments. Stand-Easy mechanisms are thus more suited to situations where an excess of cables might constitute a safety hazard, or where electrical supplies are not readily available (such as wheelchairs, etc) and where there may be more then one user The fundamental principal of operation requires that the assembly of seat, foot support(s) and their link means are mounted on a horizontal transverse pivotal axis set in a floor-standing or wheeled framework. The transverse axis is necessarily set back from the forward edge of the seat. When the seat is in its "sitting" position the footrest(s) are necessarily raised above floor level. When seated the occupant's body weight acts through a point to the rear of the pivotal axis, leaning forward and/or pressing down on the footrest and/or armrests (if fixed and non-elevating) not only causes a forward weight shift but also creates torque to rotate the seat so raising its rear. Attendant applied downforce to the footrest and/or upward force to elevating armrests also contributes to the available elevating torque. The precise geometry of any variant seat can be calculated and used to manufacture seats which demand minimal effort to meet disability needs or substantial effort to afford exercise. In any one determined form the precise effort required at any one time can be varied by the user by relatively minor posture changes throughout transition. In this way effort expended can be matched to capability. The further options include "fixed back" or "elevating back" seats, fixed or elevating armrests, reclining backs, elevating leg supports, etc A reclining back feature can be combined with an elevating legrest as in Figure 8 or the two components can be designed to function separately Suitable adjustment means include variable length parallel link(s) for which purpose lockable gas struts are ideal. Other well known means include screw and nut, lockable ratchet, slider/clamp, etc. Where armrests are fitted to either the backrest or some other attachment to the seat to the rear of the main transverse pivotal axis they will rise and fall with the rear of the seat; use of parallel connecting links or other guide means can ensure that the armrests maintain an essentially constant attitude in relation to the floor datum. This is not a common feature in such seating but, together with the similarly-moving backrest it affords unique support, both physical and mental, for the infirm. For safety reasons it is recommended that damper means be incorporated into the mechanism which can become dynamically unstable in transition due to the variation of input force and resistance throughout. The seat should also be lockable in its "horizontal" position lest unsolicited transition be initiated by the occupant leaning forward. This lock or latch should preferably be of self-latching type. Consideration to alternative lock release lever locations is recommended to suit user need or preference and/or attendant operation. A further feature enables use as a high seat, the footrest(s) being designed to fold away. Figure 7. Figure 1 shows the essential components in the sitting position; Figure 2 shows the effect of rotation to the erected state in which the footrest has reached floor level. The preferred angular rotation can be determined by geometry variation. Figures 3 and 4 show similar transitions of a seat equipped with backrest and elevating armrests. Attitude of backrest and armrests is determined by geometry of the parallel link(s) shown. Figure 5 identifies the minimum components: a seat (1) rotates about a transverse pivotal axis (4) having attached at or near its forward edge a footrest(s) (2) by link means (3). In Figure 6 the link (3) in hinged to the seat and constrained to move in a predetermined path by further links (5), all being incorporated within a framework. Figure 7 illustrates the footrest fold feature enabling use as a high seat. RECTIFIED SHEET (RULE 91) ISA/EP Figure 8 illustrates the optional recline feature in which a backrest (6) and leg support (10) are joined together by a link (7) secured in any intermediate position by a clamp (9). Link 7 may by design comprise two independent components, one linking the backrest to the frame in a position approximating to clamp 9, by use of lockable gas strut or other variable length means the backrest inclination can be varied in use. Leg support 10 is itself an option; variable length link means corresponding to the forward part of link 7 shown enables variation independent of backrest attitude. The feasibility exists to incorporate leg support 10 with footrest link(s) 3 and/or rotation of footrest 2 to extend the physical length of legrest available. Figure 9 illustrates the essential components mounted within a rudimentary floor standing framework. For safety reasons it is not recommended that this simple variant be used without a backrest unless backed by a solid wall. RECTIFIED SHEET (RULE 91) ISA/EP

Claims: CLAIMS 1. A seat, mounted upon a transverse horizontal pivotal axis set back from its forward edge is connected by link means attached adjacent to its forward edge to dependent foot support means suspended beneath, the whole being mounted within a chassis means by way of the pivotal axis attachments, said chassis means being static or wheeled, rigid or folding or incorporated into a vehicle. 2. An assembly of seat, foot support(s) and link means as in Claim 1 where the link means is articulated and equipped with guide means which further connect it to the chassis means. 3. An assembly as in Claim 1 or Claim 2 above where fixed armrests are incorporated into the chassis means. 4. An assembly as in Claim 1 or Claim 2 above together with arms attached to the moving seat or to an extension thereto. 5. An assembly as in Claim 1, Claim 2, Claim 3 or Claim 4 and equipped with a backrest attached to the chassis means. 6. An assembly as in Claim 1, Claim 2, Claim 3, or Claim 4 and equipped with a backrest attached to the seat or to an extension thereto. 7. An assembly as Claim 6 above wherein the backrest is hinged at its attachment(s) to the seat and constrained to move in a desired path by link or other guidance means which connect it to the chassis means. 8. An assembly as in Claims 1 to 7 above incorporated into a chassis which is designed to rotate about a fixed vertical axis so as to facilitate access. 9. An assembly as in Claims 1 to 8 above where the seat is designed to serve for toilet purposes or additionally equipped with commode means. 10. An a?^S ΪΪ W iJ n Claims 5or 6 above wherein means to recline the backrest relative to the seat 1 l.An assembly as in Claim 10 above wherein a hinged leg support and optional footrest(s) is independently adjustable. 12. An assembly as in Claim 11 wherein the leg support and optional footrest(s) is/are interconnected with a reclining backrest. RECTIFIED SHEET (RULE 91) ISA/EP

Inventors: BILLINGTON MICHAEL JOHN, SMITH KARL WINGETT, BILLINGTON, MICHAEL, JOHN, SMITH, KARL, WINGETT
Applicants: BILLINGTON MICHAEL JOHN, SMITH KARL WINGETT, BILLINGTON, MICHAEL, JOHN, SMITH, KARL, WINGETT
Application year: 1998
Main classification: A61G5
IPC codes: A61G5