Introduction

The present invention relates to a cushion device which is intended to be arranged on the back of a chair to support a person seated therein. More specifically, the invention relates to a cushion device which is easily vertically adjustable relative to the seat of the chair, whereby different persons can adjust the vertical posi¬ tion of the cushion to a suitable level. Background As the number of sedentary tasks increase, not least because of extended computerisation and because many people spend much time in cars, for example on their way to and from work, there is an increase in today's con¬ siderable health problems that are linked with back pains. The conventional back of a chair does not support the lumbar region adequately, for which reason manufac¬ turers of e.g. office furniture have devoted great care to developing chairs with ergonomically-designed backs, whose shape conforms to the natural curvature of the spinal column and in which the filling material is able to support loads without yielding. Similarly, car manu¬ facturers have made efforts to design the back of car seats.

A most essential factor in this context is, however, that people have differently shaped backs. Thus, each in¬ dividual has a specific ratio of back curvature to height and so forth.

A general, obvious solution to this problem has al¬ ready been tried by many people. A loose cushion is quite simply placed in the lumbar region where most symptoms of fatigue and pain appear. However, the placement of an ordinary cushion on the back of a chair immediately causes practical problems. Thus, the cushion may easily

slide downwards when the seated person is moving, it moves completely out of the desired position when the seated person is leaning forwards and it is compacted af¬ ter some time of use, whereby the desired supporting function is ruined.

In connection with chairs designed for real sitting comfort, different types of insert cushions have been used as an additional support for the seated person's back. These insert cushions have however required special provisions in the chairs to be fixed therein. For exam¬ ple, the cushions have been fixed by means of straps or the like. Several drawbacks have however been encountered in this context. Both the correct placement of the cush¬ ions in the chairs and the adjustment of a preset posi- tion are no uncomplicated operations. As mentioned above, the cushions require specially prepared chairs which thus become expensive to manufacture. Summary of the Invention

The present invention solves the above-mentioned problems by providing a cushion device to be arranged on the back of a chair to support a person seated therein, the cushion device being characterised by having the form of a separate, independent unit to be placed inclined against the back of the chair and comprises a cushion which is made of a viscoelastic material to provide elas¬ ticity and adaptation to the contour of the seated per¬ son's back and to bring about pressure equalisation, and which has a generally flat rear side, and support means for supporting the cushion when in use, in the desired vertical position relative to the seat of the chair. At least an upper portion of the support means engages the rear side of the cushion, such that the cushion and said support means are readily displaceable relative to each other, at least a lower foot-like portion of said support means being adapted to cooperate with the seat of the chair, the cushion being displaceable relative to said support means for vertical adjustment and, hence, being

adjustable to the desired position relative to the seat of the chair without necessitating any complicated opera¬ tions. The cushion device can be easily shifted between chairs with an individually set vertical position. The cushion device according to the invention thus meets the existing need of a specially prepared chair back to ensure additional support for the lumbar region by providing a separate, independent cushion device which is extremely easy to handle and adjust. The cushion de- vice according to the invention can thus be used in any type of chair that does not provide an adequate support, even in plain chairs with no upholstery at all in the back of the chair. It can also be shifted between dif¬ ferent chairs, enabling the user to bring along the cush- ion device, for example, from an office chair to a car seat. Since the cushion device according to the invention has one or more special support means for supporting the cushion in the desired vertical position relative to the seat of the chair, the problems of having a cushion liable to slide down along the backrest are avoided if the user is leaning slightly forwards or otherwise changes his position in the chair.

According to a preferred design of the invention, the cushion device comprises at the rear side of the cushion at least one support means which is inserted in at least one pocket or sleeve arranged on the rear side of the cushion. Said support means and the cushion can then be maintained in the desired position relative to each other by an adjusted frictional engagement between the support means and the pocket or sleeve.

In connection with transportation, sale, storage etc, the support means can be practically completely in¬ serted in the sleeve or pocket, whereby the cushion de¬ vice will have the size of an ordinary cushion. Advantageously, the above-mentioned friction can be achieved by using a suitable friction-producing material in said pocket or sleeve and/or on said support means,

and may be sufficiently high to retain the cushion in the desired position relative to the seat of the chair even if the person sitting in the chair is moving the upper part of its body in various ways. In this case, the fric- tion is also sufficient for maintaining the vertical po¬ sition of the cushion relative to the seat of the chair without any person leaning against it. This means that entire cushion device can quite simply be left in a chair or be shifted between different chairs in different places without necessitating any change of the individu¬ ally set vertical position. However, the friction is at the same time sufficiently low to make it easy to adapt or modify the vertical position of the cushion relative to the seat of the chair without having to get up from it, which means that the correct position can be directly achieved without any time-consuming alternate adjustments and empirical trials.

According to the invention, it is possible to use simple means for locking said support means and the cush- ion in relation to each other. Such means may serve as a supplement to other means for providing a basic engage¬ ment between said support means and the rear side of the cushion, e.g. the above-mentioned pocket or sleeve or Velcro-type fastening means. The above-mentioned locking means may advantageously be of the tightening strap type, e.g. with straps attach¬ ed to the rear side of the cushion and provided with means at the respective ends of the straps for releasable interconnection thereof, the straps cooperating with said support means to produce the desired locking effect.

According to an advantageous design of the inven¬ tion, the cushion device is further characterised in that at least a lower portion of said support means is adapted to be retained at the seat of the chair by cooperation with said portion of the support means and the seat of the chair, this cooperation being preferably based on frictional engagement. Instead of sliding forwards, the

cushion device will thus remain in an upright position in the chair if a person seated therein gets up from it. Thus, the user need not at all think about whether the cushion device will remain upright in the chair after the initial adjustment. Instead, he may get up and sit down again just as if the chair had an ordinary backrest. The friction exerted between said lower portion and the seat of the chair can be improved by means of a special fric¬ tion-producing material on the lower portion of the sup- port means.

According to a further advantageous design of the invention, the cushion device is characterised in that said lower foot-like portion is angled, preferably for¬ wards, so as to extend, when in use, substantially along the seat of the chair. In this manner, there is created between the foot-like portion and the seat of the chair a contact surface which advantageously has the shape of a relatively drawn-out rectangle. The part of the foot-like portion which thus cooperates with the seat of the chair is preferably coated with a special friction-producing material for maximum cooperation and, hence, minimum sliding of the cushion device on the chair. The support means further suitably has a transition portion extending from the lower foot-like portion and being angled back relative to the remainder of said support means. Such backward angling makes it possible to place the foot-like portion closer to the back of the chair, whereby any con¬ tact between the person sitting in the chair and the foot-like portion can be avoided. Moreover, the support means may, when not loaded, i.e. when nobody is leaning against it, act on the cushion to maintain it against the back of the seat. This design of the support means thus contributes to stabilise the position of the cushion device in the chair. As mentioned above, the cushion device is character¬ ised in that the cushion material proper, i.e. the mate¬ rial from which the cushion is made, is a viscoelastic

material, preferably Tempur™. This material, which is a polyurethane foam material, has in fact proved to be especially well suited in that it provides, by its tem¬ perature sensitivity, i.e. by softening when subjected to body temperature, excellent results in respect of pres¬ sure equalisation and pressure relief. It has been found suitable to use a material having a density of between about 40 and about 120 kg/m ³ .

According to a preferred design, the support means in the cushion device is made of a resilient material, which preferably is a plastics material and which advan¬ tageously is covered or coated with a friction-producing surface layer. The support means may advantageously be shaped as a substantially rectangular sheet or plate, the upper portion of which preferably is inserted in a pocket arranged on the rear side of the cushion. The sheet or the plate may be perforated, e.g. have a grate-like or similar structure, in order to confer the desired pro¬ perties of stiffness and yieldability. It is however pos- sible to design the support means as two or more substan¬ tially parallel parts, which are each inserted in a pocket, sleeve or similar device cooperating with the support means, and which optionally are interconnected at their base through a foot part. Alternatively, the sup- port means may comprise one or more members having a more pronounced rod or tube shape, inserted in pockets, sleeves or similar retainer mechanism cooperating with the support means in a continuously adjustable manner. Description of the Drawings Fig. 1 shows an embodiment of a cushion device according to the present invention arranged in a chair with a person sitting therein. This Figure shows how the support means maintains the cushion proper in a vertical position relative to the seat of the chair, adjusted to the curvature of the seated person's back.

Fig. 2 shows a preferred embodiment of the cushion device according to the present invention shown from the

side in an unloaded condition and with a slightly extend¬ ed support means. The ergonomically adjusted shape of the cushion proper is clearly shown, like the lower portion of the support means, provided with a foot-like design and a transition portion connecting therewith, which is slightly angled backwards relative to the rest of the support means.

Fig. 3 is a perspective view obliquely from the rear of the preferred embodiments in Fig. 2, in which the part of the rear side of the cushion which the support means engages, is designed as a pocket, in which said support means is inserted.

Fig. 4 is a perspective view obliquely from the front of the preferred embodiment in Figs 2 and 3. Fig. 5 is a view similar to Fig. 3 illustrating an¬ other embodiment of the cushion device according to the invention. Description of Embodiments of the Invention

According to preferred embodiments of the invention, the cushion device is designed for use applied against a backrest 1 of substantially ordinary design. The cushion proper 4 is ergonomically adjusted to the curvature of the seated person's back. This means that the cushion 4, as seen from the side, is so designed as to be substan- tially thicker at its central portion than at the edges. The expression "substantially thicker" as here used means that the cushion 4 is about twice as thick at its central portion than at the edges. Advantageously, the lower edge is slightly thicker than the upper, it being also con- ceivable to use a cushion 4 having its thickest portion slightly below the centre. As viewed straight from the front, the preferred embodiment is substantially square, optionally slightly wider than it is high. The rear side 10 in the preferred embodiments of the invention is sub- stantially flat.

The support means 5, designed as a continuous part and inserted from below into a fabric pocket 8 sewn to

the rear side 10 of the cushion 4, is also substantially flat for optimum cooperation between the support means 5 and the rear side 10 when engaging each other. In a pre¬ ferred design, the support means 5 is a rectangular, thin sheet 11 made of a resilient material and covered by a fabric 12. At the base, the sheet has a forwardly-angled, flange-shaped, foot-like portion 6 with in use extends substantially parallel along the seat 3 of the chair, and a transition portion 7 connecting with the lower foot- like portion 6 and being angled backwards relative to the remainder of the support means 5. On its underside, the foot-like portion 6 has an additional surface layer 9 of a special friction-increasing material, which also extends slightly into the transition portion 7. When the preferred embodiments are viewed from the rear (Figs 3 and 5), it will been seen that the pocket 8 in which the support means 5 is inserted, makes up about a third of the total width of the cushion proper 4 and that it is centrally disposed on the rear side 10 of the cushion 4, the opening of the pocket 8 being located at the base portion of the cushion 4. The support means 5 has such a length that, when maximally inserted in the pocket 8, the foot-like lower portion 7 substantially connects with the lower edge of the cushion. The size of the pocket 8 in relation to the support means 5 is such that the fabric forming the pocket 8 is maintained con¬ stantly tensioned, whereby the required friction is pro¬ duced, at the same time as the tension in the fabric is not as high as to prevent also the backwards-angled, resilient transition portion 7 connecting with the foot¬ like portion 6 from being inserted in the pocket 8 and readily pulled out of it when the pocket is deep (Fig. 3) .

In the embodiment of Fig. 3, the pocket 8 extends approximately from the base of the cushion 4 to the upper portion thereof, although the opening of the pocket might very well be located higher up on the rear side of the

cushion. Here, the engagement between the support means 5 and the pocket 8 is completely friction-conditioned. It is understood that, when in use, the cushion 4 is direct¬ ly continuously displaceable relative to the support means 5.

The embodiment of Fig. 5 differs from that of Fig. 3 in that the pocket 8 has its opening located higher up on the rear side, i.e. the pocket is not equally deep, and in that the cushion device is supplemented with a locking function for the support means 5 in the form of a tighten¬ ing strap 21 provided with a Velcro-type strip 22. The tightening strap 21 has a central portion 23 fixed to the rear side of the cushion immediately below the opening of the pocket 8 and extending parallel to it. The tightening strap has two free strap portions 24, 25 intended to be placed around the support means 5 from each side and attached to each other by means of the Velcro strip 22, so that the support means is strapped and safely retained in the set position. It is understood that this locking feature supple¬ ments the frictional engagement exerted between the sup¬ port means 5 and the pocket 8, for which reason the fric¬ tional engagement in this case may be looser than in the embodiment of Fig. 3. Consequently, this design allows for a choice between a more or less substantial engage¬ ment between the cushion and the support means by using or by not using the tightening-strap locking means, which may of course be more or less strong in itself.

The cushion material proper in the preferred embodi- ments is the viscoelastic material Tempur™. The fabric enwrapping the cushion material proper and the support means 5 and also forming the pocket 8 on the rear side 10 of the cushion 4 may, for example, be machine-washable corduroy. The support means 5 is made of thermoplastic, e.g. polystyrene plastic.

The dimensions of the preferred embodiment according to the invention are e.g.:

Cushion height: about 35 cm Cushion width: about 40 cm Maximum thickness of cushion: about 8 cm Width of support means: about 18 cm Length of support means: about 33 cm

Thickness of support means: about 0.5 cm Width of pocket: about 18 cm Length of pocket: about 30 cm (Fig. 3) or about 25 cm (Fig. 5) .