WO1991010382A1

WO1991010382A1 - A chair

Info

Publication number: WO1991010382A1
Application number: PCT/DK1991/000014
Authority: WO
Inventors: Oluf Lund
Original assignee: Trio-Line A/S
Priority date: 1990-01-22
Filing date: 1991-01-21
Publication date: 1991-07-25
Also published as: EP0512028A1; DK17690A; DK163953C; DK17690D0; DK163953B

Abstract

A chair (1) comprises a base frame (2), a seat member and a back member, the seat member comprising a seat cushioning (6) with a seat-supporting surface, the back member comprising a back cushioning (7) with a back-supporting surface, the back member being fixed or optionally pivotable relative to the seat member. In order to provide a user with a choice between a sitting posture and a rest posture, a further reversible member (11) is fitted, said member comprising a cushioning (14) and being pivotable about an essentially horizontal and transversely extending axis (10) arranged at a distance below the seat member between an upright position where the reversible member cushioning is lying adjacent to and along the back member, offering a back-supporting surface, and a lowered position where the reversible member cushioning provides a forward extension of the seat member, offering support of the shanks of an occupant of the chair.

Description

A Chair

The present invention concerns a chair, e.g. an arm chair, with an adjustment facility offering the choice between two alternative po- stures, such as a posture for sitting straight, well suited for activi¬ ties such as conversation, reading, watching television and the like, and an alternative posture ideally suited for rest. Throughout this text the term "sitting posture" refers to a posture in which an occupant of the chair sits with a comparatively upright or straight support of the back, keeping his or her feet onto the floor, whereas the term "rest po¬ sture" refers to a posture, in which an occupant sits with the feet ele¬ vated from the floor, the shanks being supported by a foot stool or si¬ milar means, and possibly leaned more backwards.

The prior art comprises numerous types of chairs with an adjustment facility designed to accomodate particular preferences as to the type of chair or in order to offer a user the choice of adapting the chair for a variety of purposes or to allow an occupant to change his or her sitting posture from time to time. A rest posture with the feet elevated may on some occasions be quite comfortable, but may on other occasions be unde- sirable, e.g. in case an occupant wants to be able to get up quickly. A chair with an integrally fixed extension for support of the shanks will inevitably be rather long so that a user will want to have the possi¬ bility of removing the shank support member when not in use in order to make the chair occupy less space. The prior art comprises chairs with pivotted flaps adapted to be swung upwards to a position where they can support the shanks, and to be turned or swung downwards when not in use. This design is not quite satisfactory as the flaps when folded down make the chair look unattractive and rather heavy, and as these flaps will obstruct activities, e.g. cleaning below the chair. An additional disad- vantage by this type of chair is the need for providing a type of ar¬ rester mechanism representing a complication of the use.

The adjustment or manouvering mechanism may be designed in nume¬ rous, different ways not to be elaborated further herein. It is suffi¬ cient to say that solutions allowing a user to adjust the support member in question by gripping it with one hand and moving it to the position desired tend to be most easily understandable and attractive to a user. It is, however, generally necessary to provide additional means in order to allow a user to arrest the support member in question once the po- sition desired has been reached. These means may comprise an extra con¬ trol lever or may comprise a socalled automatic arrester mechanism, which automatically locks the support member upon moving it through a special programme of motions not readily obvious to a user. Either of these basic principles of the design of the arrester means is perceived as difficult to use to such a degree where a greater proportion of users desists from using them.

By any type of chair the shape of the back-supporting surface is an important aspect, and it is well known in the art that the optimum shape is different depending upon the intended use of the chair. For sitting in a straight posture, e.g. during conversation, an occupant prefers a comparatively upright or straight supporting surface for the back which should not interfere with the unhindered motion or turning of the head. On the other hand, for a rest posture it is frequently desirable to have a surface for supporting the head, e.g. a protruding head rest.

It is further preferred that the back support surface is inclined further backwards for a rest posture than it is desirable for higher le¬ vels of activity, and the prior art comprises numerous chairs with a fa¬ cility for tilting the back in order to satisfy this desire. Tilting of the back of a chair where the seat is fixed, however, makes it necessary for an occupant to displace his or her position relative to the seat surface as well as relative to the back surface, and in case these surfaces are shaped so as to accomodate the body, the back cannot tilt very far before the shape of the surfaces no longer accomodates an occu- pant very well. Adjustment of the back inclination further makes it necessary to provide controllable arrester mechanisms causing complica¬ tions as discussed above.

A greater range of inclinations without detracting from the fit of the shaping of the surfaces may be obtained by tilting the seat and the back together as a block, i.e. while keeping the angle between them constant or essentially constant. The prior art also comprises chairs offering this possibility, but they exhibit other substantial disadvan¬ tages.

According to one design of a chair of this general category, a tilt axis is arranged below the seat, i.e. below the center of gravity of the combined seat and back. This chair is balanced when the center of gravi¬ ty is just above the tilt axis, but there is an instability during the adjustment motion as soon as the chair is tilted away from the balanced position, which is undesirable and may even take a user by surprise, in particular near the extreme positions. The stability problem may be avoided by a modified design of chairs within this category by arranging the tilt axis at or above the combined center of gravity of the seat and the back, e.g. by providing the chair with curved rails or similar means, upon which the combined seat and back can roll. In this case the elevation of the seat front edge above the floor will, however, vary, being at a minimum in the straight sitting posture and at a maximum in the rest posture, which is totally undesirable in view of the user com- fort.

In order to provide a chair where seat and back are tilted as a block around a horizontal, transverse axis, this axis should preferably be arranged near the seat front edge to place it adjacent an occupant's knee joints in order to obtain the optimum elevation above the floor in all positions. Hereby the tilt axis will, however, inevitably be situa¬ ted rather far away from the center of gravity of the tiltable portion, whereby a user will have to elevate or lower a substantial weight, ma¬ king it necessary to arrange spring mechanisms, screw-threaded rods, large lever mechanism or other complex mechanisms in order to provide a practical solution.

The invention provides a chair comprising a base frame, a seat mem¬ ber and a back member, said seat member comprising a seat cushioning with a seat-supporting surface, said back member comprising a back cu¬ shioning with a back-supporting surface, said back member being fixed or pivotable relative to the seat member, said chair further comprising a reversible member, said reversible member being fitted with a cushioning and being pivotable about an essentially horizontal, transverse axis ar¬ ranged at a distance below the seat member, between an upright position, in which the reversible member cushioning is resting adjacent to and along the back member and offers back support, and a lowered position, in which the reversible member cushioning provides a forward extension of the seat member offering shank support for an occupant of the chair. Hereby a chair is provided, by which the shank support member may be turned forwards or turned away as necessary in an extremely simple manner, and by which the shank support member neither is in the way nor detracts from the appearence of the chair when not in use. When the re¬ versible member or the turnable flap used as support for the shanks is turned backwards towards the back of the chair, the side of the rever- sible member then turned upwards or forwards serves as back support sur¬ face. This makes it possible to design the back portion of the chair with a shape which is ideal for the rest posture, i.e. with a slightly recessed back support surface and a protruding head rest, while a diffe- rent shape of the supporting surface, more preferred for the straight sitting posture, may be obtained by a suitable design of the back sup¬ port surface of the reversible member without being bound by or re¬ stricted to the shape of the back of the chair.

According to a preferred embodiment the invention provides a chair, by which the seat member is pivotable relative to the base frame about an essentially horizontal, transversely extending axis arranged below the seat-supporting surface at a short distance behind the forward edge of the seat member between a sitting posture and a rest posture, said reversible member being provided with means for movably supporting the seat member at a point situated at a distance behind the pivot axis of the seat in order that the rear portion of the seat is lowered when the reversible member is lowered, whereas the rear portion of the seat is elevated when the reversible member is turned to the upright position. Hereby a chair is provided, by which seat and back may be tilted slightly backwards to the rest posture or be raised slightly upwards, respectively, for a sitting posture by tilting about a horizontal, transverse axis arranged closely to the seat front edge, whereby it is achieved that the elevation of the front edge above the floor is ideal for both postures of the chair, and it is further achieved that the re- versible member can be used as a lever, whereby the seat and back por¬ tion of the chair may be tilted upwards and downwards without great effort.

According to a preferred embodiment the mechanism for supporting the seat member is adapted to move the seat and back portion by the up- ward motion of the reversible member past a dead point and to lower it slightly during the last portion of the motion of the reversible member. This provides a self-arresting, stabilizing effect upon the reversible member when in the upright position, the weight of the seat and back serving to press the reversible member back against the back of the chair.

According to a preferred embodiment the chair is designed so that the seat inclination in the sitting posture is approximately 10 degrees from horizontal, while it is approximately 25 degrees from horizontal in the rest posture, meaning that the chair is tilted through approximately 15 degrees between the two postures. The side of the reversible member, which is turned upwards when this member is in the lowered position, i.e. the surface for support of the shanks, is approximately horizontal in that position.

According to a further preferred embodiment a further support means is pivotably connected to the reversible member and adapted to be dis¬ placed slightly forwards from the front edge of the seat of the chair, when the reversible member is turned down, to a position where the sup- port means offers support of the reversible member. This provides a stable and well defined support of the reversible member when in the lo¬ wered position.

According to a further preferred embodiment the base frame of the chair is constructed from spring steel, whereby the chair is allowed to rock slightly.

The invention will be more fully understood from the following de¬ tailed description given with reference to the drawings, on which

figure 1 shows a side elevation of a chair according to a first, preferred embodiment in the sitting posture, figure 2 is similar to figure 1, but showing the chair in the rest posture, figure 3 is a side elevation of a chair according to a second em¬ bodiment of the invention and shown in the sitting posture, figure 4 is a side elevation of the chair from figure 3, but in the rest posture, figure 5 is a side elevation of the base frame and of the framework for the seat and the back of a chair according to a third embodiment of the invention, and shown in the sitting po- sture, figure 6 shows the same components as figure 5, but with the framework for the seat and the back in the rest posture, figure 7 is a top plan view of the same components as shown in fi¬ gure 5 and figure 6 and in the rest posture, figure 8 is a side elevation of the base frame, the reversible mem¬ ber and a support means for a chair according to the third embodiment of the invention, and in the sitting posture, figure 9 shows the same components as figure 8, but in the rest po- sture, and figure 10 is a top plan view of the components from figures 8 and 9 in the rest posture.

All drawings are simplified views showing only the components which are essential to the understanding of the invention, unnecessary details being omitted from the drawings. Throughout the drawings identical or similar components are marked with the same reference numerals.

Reference is first made to figures 1 and 2, showing side elevations of a chair 1 according to the first embodiment of the invention, the main components being a base frame 2, a seat cushion 6, a back cushion 7, a head rest 8, and a reversible member 11. The base frame 2 comprises a foot 3 adapted to rest on a horizontal base or floor, the foot 3 being provided with a forwardly and upwardly inclined cantilever beam 4. A pi- vot 10 is attached to the cantilever beam approximately midways, and the cantilever beam is at the top end solidly and rigidly connected with the seat cushion adjacent the front edge thereof. The seat cushion 6 is ri¬ gidly and solidly connected with the back cushion 7 solidly and rigidly connected with the head rest 8. The pivot 10 is arranged with a pivot axis extending horizontally and transversely to the chair. The seat of the chair is located with its midpoint at some distance above the pivot axis. The pivot 10 is the pi¬ vot link for a reversible member 11 comprising beams extending trans¬ versely from the pivot 10 to both sides of the seat cushion and extend- ing upwards along both sides to the turnable or reversible cushion 14 shown in figure 1, resting adjacent to and along the surface of the back cushion 7. A person using the chair in the posture as shown in figure 1 will have his or her seat on the seat cushion 6, the back supported on the back-supporting side 15 of the reversible cushion 14 and may lean his or her head or neck backwards for support on the head rest 8.

If a user wants support for sitting with the feet elevated from the floor, he or she will grip the reversible member 11 and turn it down from the position shown in figure 1 and to the position shown in figure 2, where parts of the reversible member 11 will rest on the upper por- tion of the cantilever beam 4, understanding that the reversible member is adapted so that the reversible cushion in this position will assume an approximately horizontal position with the shank support side 16 turned upwards. The back cushion 7 is shaped so as to provide a comfor- table back support surface, and since the reversible cushion has some thickness, it will easily be understood by a comparison of figures 1 and 2 that a user in the rest posture will perceive the head rest 8 as pro¬ truding further forwards relative to the situation in the sitting po- sture, i.e. an occupant's head is well supported in the figure 2 po¬ sture.

Reference is now made to figures 3 and 4, showing a second embodi¬ ment of the invention in planar elevation. The second embodiment differs from the first embodiment mainly by the seat cushion 6 being attached to the cantilever beam 4 in a region below the seat front edge by means of a pivot 5 with a transversely extending axis so that the upper portion of the chair comprising the seat and back may tilt about the pivot 5 re¬ lative to the cantilever beam 4 of the base frame. A support for the seat cushion is arranged at a position rearwards from the pivot. This support is realised by providing the seat cushion 6 with plane bearings or slide rails 9 on the lower side, whereas the reversible member com¬ prises a cross member 12 bearing against the plane bearings 9. By turn¬ ing of the reversible member from the position shown in figure 3 and down to the position shown in figure 4 a shank support and a support surface for the back are obtained, generally corresponding with that shown in figure 2, but with the seat cushion and back cushion tilted or inclined as a block backwards to the position shown in figure 4, which is the rest posture. It is understood that the other components shown in figures 3 and 4, and not mentioned specifically, are similar to the com- ponents of the embodiment shown in figures 1 and 2, so reference may be had to the explanation given above.

In the following a third embodiment of the chair is explained in more detail referring to figures 5 through 10.

In order to be able to illustrate clearly the components of the chair according to the third embodiment, the upholstery is omitted from the drawings 5 through 10, and it is considered to be obvious to persons skilled in the art how suitable upholstery could be designed and applied onto the chair of the third embodiment, so that it is not necessary to illustrate the upholstery specifically in this embodiment. Figures 5, 6 and 7 illustrate a base frame generally similar to the base frame 2 explained above and a frame portion for the seat and the back and for the head rest, i.e. a frame portion to be used in order to support elements similar to the seat cushion 6, the back cushion 7 and the head rest 8 explained above.

In the third embodiment the base frame 22 comprises a foot 23 ha¬ ving a planar outline essentially as an H (cf. figure 7) and possibly slightly offset or cranked near the ends (cf. figures 5 and 6), or pos- sibly provided with foot pads at the ends to provide a good stand on a horizontal supporting surface. The foot may be constructed in solid spring steel. An inclined cantilever beam 24 extending upwardly and for- wardly, and also of spring steel, is welded to the connecting branch of the H. The cantilever beam has an approximately U-shaped, planar outline (cf. figure 7), a transversely extending, round steel bar 28 being at¬ tached near the upper portion by small straps 29 allowing the round steel bar to roll so as to provide a pivot connection.

The seat framework comprises four mutually parallel, longitudinal beams 30 welded to the round steel bar at their front ends. Slide rails or plane bearings 35 for support of the seat framework are attached to the lower sides of two of the longitudinal beams 30. A forward beam 26 extending transversely and at the sides upwards inclined, the ends being bent rearwards in order to support the upholstery, is welded to the front ends of the longitudinal beams. The longitudinal beams 30 are near their rear ends welded to a transverse beam 27, the ends of the trans¬ verse beam being connected with side beams 32 extending rearwardly, their rearmost ends being interconnected by a transverse beam 33. A tube 31 bent approximately into a U-shape is welded to the transverse beam 27 so as to extend rearwardly in the plane of the longitudinal beams 30. A piece of tubing 34 is bent or shaped so as to define the edges of the back and welded at the lower portion to the U-shaped tubing 31 and at the upper portion to the transverse beam 33 in order to provide a solid framework construction. The tubing 34 defining the back forms rounded corners suitable for the fitting of upholstery. Reference is now made to figures 8, 9 and 10, showing additional components of the chair according to the third embodiment. These figures show again the base frame 22 explained above and a framework portion for a member generally similar to the reversible member 11 explained with reference to figure 1. Figures 8, 9 and 10 again show the base frame 22 explained with re¬ ference to figures 5, 6 and 7, and figures 8, 9 and 10 further show a pivot for the reversible member 41, said pivot comprising a round steel bar 44 pivotable in U-shaped straps 29 attached to the base framework cantilever beam 24 adjacent the midregion thereof. From figure 10 it may be seen that the reversible member 41 comprises two short supporting arms 45 extending from the round steel bar 44 and welded at their front ends to a transversely extending cross member 42. The ends of the cross member 42 extend into side beams 43 extending in the left hand direction in figure 10 to end regions where they are bent obligely rearwards so as to form trapezoidly extending side struts 46. The side struts 46 are in¬ terconnected between their leftmost portions as seen in figure 10 by a comparatively long cross bar 47 and between their rightmost portions as seen in figure 10 by a comparatively shorter cross bar 48, both cross bars being welded to the side struts. A cushion may be fitted to the re¬ versible member suspended between the side struts 46 and the cross bars 47 and 48.

The cross member 42 supports the seat framework, the plane bearings 35 sliding on the cross member so that the reversible member when moved will tilt the framework of the seat in a similar way as in the second embodiment of the invention explained above with reference to figures 3 and 4.

As illustrated most clearly in figure 8, the reversible member side beams 43 extend angled slightly away from the direction of the support¬ ing arms 45, and the side struts 46 are further angled out of the plane of the side beams 43. The cross bars 47 and 48 are slightly curved in a concave direction, i.e. to the right as shown in figure 7, so as to match the shape of the upholstery of the back of the chair (the uphol- stery not being shown). The distance between the reversible member side beams 43 is sufficient to make them clear the sides of the seat over the full range of the turning motion.

Figure 10 shows an approximately rectangular support frame 51 at¬ tached at one end by means of a pivotable fixture 52 to the reversible member cross member 42. The support frame 51 rests on the round steel bar 28 and is restrained in the upwards direction by the forward beam 26 of the seat extending just above the round steel bar 28 when the chair is assembled. The clearance between the round steel bar 28 and the for¬ ward beam 26 (cf. figures 6 and 7) is sufficient to allow the support frame 51 to slide forwards and rearwards when the reversible member is moved by means of the coupling to the cross member 42. With the rever¬ sible member in the upright position as shown in figure 8 the support frame 51 is fully retracted so that it will be concealed below the seat cushioning (not shown) when installed. When the reversible member 41 is lowered to the position illustrated in figure 9, the support frame 51 will slide forwards to offer support to the reversible member in the re¬ gion near the cross bar 48 in order to provide a firm support and an ac- curate definition of the position of the reversible member when lowered. Although particular embodiments of the chair have been described, more detailed, the chair can obviously be modified within the scope of the invention. It is e.g. possible to modify the back so that it could be tilted relative to the seat by providing a pivot means near the rear- ward portion of the U-tubing 31 to support the tubing of the back, an adjustment facility being provided by making the side beams 32 longitu¬ dinally adjustable. Thus the detailed explanation is given as example only and is not intended to limit the scope of the invention to be de¬ fined only by the claims.

Claims

WHAT IS CLAIMED IS

1. A chair comprising a base frame, a seat member and a back mem¬ ber, said seat member comprising a seat cushioning with a seat-support- ing surface, said back member comprising a back cushioning with a back- supporting surface, said back member being fixed or pivotable relative to the seat member, c h a r a c t e r i z e d by comprising a further reversible member, said reversible member being fitted with a cushioning and being pivotable about an essentially horizontal, transverse axis ar- ranged at a distance below the seat member between an upright position, in which the reversible member is resting adjacent to and along the back member and offers back support, and a lowered position, in which the re¬ versible member is resting to provide a forward extension of the seat member offering shank support for an occupant of the chair.

2. The chair according to Claim 1, c h a r a c t e r i z e d by the upper side of the reversible member cushioning extending essentially horizontally when the reversible member is in the lowered position.

3. The chair according to Claim 1 or Claim 2, c h a r a c t e r i z e d by a support means being pivotably connected to the reversible member about an axis extending at some distance from and parallel with the axis for the pivotting of the reversible member, said supporting means being supported slidably forwardly and rearwardly at a region be- low and adjacent to the seat front edge so that the supporting means slides by the motion of the reversible member between a retracted posi¬ tion below the seat, when the reversible member is in the upright posi¬ tion, and a forwardly extending position offering support of the rever¬ sible member when the reversible member is in the lowered position.

4. The chair according to any of the preceding Claims, c h a r a c t e r i z e d by the seat member being pivotable relative to the base frame about an essentially horizontal, transversely extending axis ar¬ ranged below the seat-supporting surface at a short distance behind the forward edge of the seat member between a sitting posture and a rest po¬ sture.

5. The chair according to Claim 4, c h a a c t e r i z e d by said reversible member being provided with means for movably supporting the seat member at a point situated at a distance behind the pivot axis of the seat in order that the rear portion of the seat is lowered when the reversible member is lowered, whereas the rear portion of the seat is elevated when the reversible member is turned to the upright posi¬ tion.

6. The chair according to Claim 5, c h a r a c t e r i z e d by said seat member being provided with plane bearings or slide rails on the lower side, said reversible member comprising a cross member adapted to bear against said plane bearings.

7. The chair according to any of the preceding Claims, c h a r a c t e r i z e d by being adapted so that the seat rear portion is by the turning of the reversible member from the lowered position towards the upright position initially elevated to a point slightly above the in¬ tended sitting posture, whereafter it, during the last portion of the motion of the reversible member towards the back of the chair, is lo¬ wered slightly into its intended sitting posture so that the mass of the seat serves to press the reversible member against the back of the chair to keep it in place in the sitting posture.

8. The chair according to any of the preceding Claims, c h a r a c t e r i z e d by the inclination of the seat-supporting surface in the sitting posture of the chair being around 10 degrees from horizontal, whereas it is around 25 degrees from the horizontal in the rest posture.

9. The chair according to any of the preceding Claims, c h a r a t e r i z e d by the base frame being constructed from spring steel capable of allowing a slight, rocking of the chair.