NL2028153B1

NL2028153B1 - Backrest and chair

Info

Publication number: NL2028153B1
Application number: NL2028153A
Authority: NL
Inventors: Antonius Maria Staarink Henricus; Bijtelaar Marike
Original assignee: Life & Mobility Dev B V
Priority date: 2021-05-05
Filing date: 2021-05-05
Publication date: 2022-11-23
Also published as: EP4085888A2; EP4085888A3

Abstract

Backrest for supporting the back of a seated person comprising a rigid back rest frame and a back support structure comprising substantially nonelastic, flexible sheet material and comprising a central region and at least four lateral segments, wherein the back rest support surface in its loaded condition has a form-stable, a three-dimensionally curved shape of which a cross-sectional view in the sagittal plane shows a back rest support surface curvature which substantially corresponds with the vertebral curvature at least in a region which corresponding with the lumbar region and a transition region which is formed by a lower part of the thoracic region and an upper part of the lumbar region.

Description

P128402NL00 Title: Backrest and chair

FIELD The invention relates to a backrest for supporting the back of a seated person, as well as to a chair.

BACKGROUND WO01/60209 A1 discloses a back rest which provides good support to the back of a seated person. As explained in that publication, support of the lumbar-thoracic transition region, i.e. the part of the back that extends approximately from the ninth thoracic vertebra from above (T9) to the second or third lumbar vertebra from above (L2/L3), can be used both functionally and constructionally for defining the desired posture first and subsequently supporting the lower part and preferably also the upper part of the back individually from there, irrespective of the shape of the individual back in sagittal and in transversal section. The individual posture support that can be achieved by this approach is maximal.

SUMMARY The construction described in WO01/60209 A1 is relatively expensive. The present invention has as an object to provide an alternative backrest which includes the advantages of the backrest of WO01/60209 A1 and of which the manufacturing costs may lower and which may even provide even further improved support to the back of a seated person. To that end, the invention provides a backrest for supporting the back of a seated person according to claim 1. As shown in Figs. 7A, 7B and 7C, and as generally known, the human vertebral column has a sacral region, a lumbar region defined by lumber vertebrae (L1-L5), a thoracic region defined by thoracic vertebrae

(T1-T12) and a cervical region defined by cervical vertebrae (C1-C7). When viewed In a cross section along a sagittal plane the vertebral column has a vertebral curvature.

The backrest comprises a rigid back rest frame and a back support structure.

The rigid back rest frame has two opposite lateral back rest frame members. The lateral back rest frame members are shaped along a lateral back rest frame curvature which, when viewed from a lateral side, substantially corresponds to the vertebral curvature at least in an upper part of the lumbar region and a lower part of the thoracic region.

The back support structure comprising substantially non-elastic, flexible sheet material. The back support structure defines, in a loaded condition, i.e. when a person is resting with his or her back against the backrest, a form-stable back rest support surface. The back support structure comprises a central region and at least four lateral segments. The central region has two opposite lateral edges and an upper and a lower edge. Each lateral segment of the at least four lateral segments has an inner and an outer lateral edge. Each lateral segment is connected with its inner lateral edge with the lateral edge of the central region and with its outer edge with an associated one of the lateral back rest frame member. The lateral segments are arranged in pairs of lateral segments which are connected to the central region at the same height to the opposite lateral edges of the central region. A first pair of lateral segments is connected to a first central region segment and a second pair of lateral segments is connected to a second central region segment.

The back rest support surface in its loaded condition has a form- stable, three-dimensionally curved shape of which a cross-sectional view in the sagittal plane, i.e. a substantially vertical plane which is centrally positioned between the two lateral back rest frame members, shows a back rest support surface curvature which substantially corresponds with the vertebral curvature at least in a region which corresponding with the lumbar region and a transition region which is formed by a lower part of the thoracic region and an upper part of the lumbar region. The invention also provides a chair for supporting a seated person according to claim 25. In particular the invention provides a chair comprising a seat and the backrest according to the invention. The chair may include wheels so as to form a wheelchair.

Due to the provision of at least two pairs of lateral segments, the shape and the position/orientation of the first central region segment and the second central region segment may be selected as best fitted to the user by selecting the desired shape of the opposite lateral back rest frame members. Due to the non-elastic, flexible sheet material of the back support structure, the firm back rest support is provided which is of the essence for a good long term support of the seated person. Elastic sheet material, e.g.

elastic knitted fabric, is not feasible for the back support structure according to the invention because the position stability of the seated person would not be provided.

The curvation of the back rest frame, together with the size of the central region, the sizes of the lateral segments, and the placement of the lateral segments with respect to the central region and their associated lateral back rest frame member, all have an effect on the form-stable three- dimensionally curved shape of the back rest support surface. These may all be chosen such that the backrest offers optimal support for the back of the seated person.

The vertebral column is supported by the central region. The sides of the back, i.e. the parts of the back lateral to the vertebral column, are supported by the lateral segments.

Best support is provided if a critical support region of the vertebral column is firmly supported in a fixed position and orientation. The critical support region is formed by the lumbar region and the transition region formed by the lower part of the thoracic region and the upper part of the lumbar region. The transition region of the lower part of the thoracic region and the upper part of the lumbar region runs approximately from the second lumbar vertebra (L2) to the ninth thoracic vertebra (T9). With the backrest and the chair according to the invention, optimal support for the critical support region is achieved by having the size and the position of the segments such that the curvation of the back support structure at the position associated with the critical support region, matches the curvation of the region. Because the back support structure of the backrest and the seat according to the invention is made of a non-elastic material, it will not stretch in a loaded condition. This means that the back rest support surface not only is positioned and oriented in the optimal position for giving optimal support to the back of the seated person, but also will remain in that position and orientation.

In another aspect, a chair is provided, optionally including a backrest according to the invention, wherein the chair has seat comprising a rigid seat frame and a seat support structure. The rigid seat frame has two opposite lateral seat frame members. The lateral seat frame members are shaped along a lateral seat frame curvature which, when viewed from a lateral side, substantially corresponds to a buttock curvature when viewed in cross section along a sagittal plane.

The seat support structure comprises substantially non-elastic, flexible sheet material and defines, in a loaded condition, i.e. when a person is resting with his buttocks on the seat, a form-stable seat support surface.

The seat support structure comprises a central seat region having two opposite lateral edges and a front and a rear edge. Additionally, the seat support structure comprises at least four lateral seat segments. Each lateral seat segment has an inner and an outer lateral edge and is connected with its inner lateral edge with the lateral edge of the central seat region and with its outer edge with a lateral seat frame member. The lateral seat segments are arranged in pairs of lateral seat segments which are connected to the central seat region at directly opposite parts of the lateral edges of the central seat region. A first pair of lateral seat segments is connected to a first central seat region segment. A second pair of lateral seat segments is 5 connected to a second central seat region segment. The form stable seat support surface has a three-dimensionally curved shape of which a cross- sectional view in the sagittal plane, 1.e. a substantially vertical plane which is centrally positioned between the two lateral seat frame members, shows a seat support surface curvature which substantially corresponds with the buttocks curvature, wherein the three-dimensionally curved seat support surface substantially corresponds to the three-dimensionally curved, anatomical shape of the buttocks of the seated person.

Thus, a chair is provided with a stably supporting seat. The pressure distribution on the buttocks of the user is optimal due to the 3D- shape of the seat support structure. In particular when the angle of the first central seat region is set correctly, any shear forces between the buttocks of the user and the seat support structure may be minimalized. The seat has the additional advantage that the chair with the seat may be collapsible.

The present invention will be further elucidated with reference to figures of an example in which various embodiments of the invention are incorporated. The embodiments may be combined or may be applied separately from each other.

BRIEF DESCRIPTION OF THE FIGURE Fig. 1 shows a perspective view of an example of a wheelchair according to the invention; Fig. 2 shows a front view of the example of figure 1; Fig. 3 shows a side view of the example of figures 1 and 2. Fig. 4 shows a perspective view of another example of a wheelchair according to the invention;

Fig. 5 shows a front view of the example of figure 4; Fig. 6 shows a rear view of the example of figures 4 and 5; Figs. 7A, 7B, 7C show a front view, a side view and a rear view of the human vertebral column.

DETAILED DESCRIPTION In this application similar or corresponding features are denoted by similar or corresponding reference signs. The description of the various embodiments 15 not limited to the examples shown in the figures and the reference numbers used in the detailed description and the claims are not intended to limit the description of the embodiments, but are included to elucidate the embodiments by referring to the example shown in the figures. In the most general terms, the invention relates to a backrest 10 for supporting the back of a seated person. As explained in the summary and shown in Figs. 7A, 7B, and 7C, the human vertebral column has a sacral region, a lumbar region defined by lumber vertebrae L1-L5, a thoracic region defined by thoracic vertebrae T1-T12 and a cervical region defined by cervical vertebrae C1-C7. When viewed in a cross section along a sagittal plane has a vertebral curvature. The vertebral curvature is also visible in the side view of Fig. 7B. The backrest 10 comprises a rigid back rest frame 16 and a back support structure 22. The rigid back rest frame 16 has two opposite lateral back rest frame members 18, 20. The lateral back rest frame members 18, 20 are shaped along a lateral back rest frame curvature which, when viewed from a lateral side, substantially corresponds to the vertebral curvature at least in an upper part of the lumbar region and a lower part of the thoracic region. The back support structure 22 comprises substantially non-elastic, flexible sheet material.

In an embodiment, the flexible sheet material of the back support structure may be chosen from the group the group consisting of canvas, cloth and foil. Substantially non-elastic is to be construed as a material which, when used in the seat support structure substantially does not have an elastic or deflecting behaviour when being subjected to a load. The characterization of fabrics with respect to elasticity and non-elasticity depends on many factors, like weave structure, type of coatings applied etc. as well as the direction in which the forces are applied relative to the weave pattern. A well-defined method for characterizing fabrics is provided in DIN EN ISO 1421/1 which defines a tensile strength at breakage, as well as the elongation at breakage of a test strip. On the basis of DIN EN ISO 1421/1 the term “substantially non-elastic” used in this embodiment refers to sheet material having an elongation at breakage of less than 50% in any direction of pulling. An example of a flexible sheet material within the material group which is generally referred to as canvas and which complies with the above defined requirement of having an elongation at breakage of less than 50% in any direction of pulling is Cordura 5080 of the Firm C.F. Weber GmbH from Spitzkunnersdorf, Germany. Typically, this is a polyamide 6.6 material with a plain weave structure which has been subjected to a water, oil and dirt repellency fluorocarbon treatment and which has been coated with a flame retardant PU dispersion coating.

The back support structure 22 defines, in a loaded condition, i.e. when a person is resting with his back against the backrest 10, a form- stable back rest support surface 24. The back support structure 22 comprises a central region 26, 28, 30 and at least four lateral segments 34a, 34b, 36a, 36b, 38a, 38b. The central region 26, 28, 30 has two opposite lateral edges 32 and an upper and a lower edge. Each lateral segment 34a, 34b, 36a, 36b, 38a, 38b of the at least four lateral segments 34a, 34b, 36a, 36h, 38a, 38b has an inner and an outer lateral edge. Each lateral segment 34a, 34h, 36a, 36b, 38a, 38b is connected with its inner lateral edge with the lateral edge 32 of the central region 26, 28, 30 and with its outer edge with an associated one of the lateral back rest frame member 18, 20. The lateral segments 34a, 34b, 36a, 36b, 38a, 38b are arranged in pairs of lateral segments which are connected to the central region 26, 28, 30 at the same height to the opposite lateral edges 32 of the central region 26, 28, 30. A first pair of lateral segments 34a, 34b is connected to a first central region segment 26 and a second pair of lateral segments 36a, 36b is connected to a second central region segment 28.

The back rest support surface 24 in its loaded condition has a form- stable, three-dimensionally curved shape of which a cross-sectional view in the sagittal plane, 1.e. a substantially vertical plane which is centrally positioned between the two lateral back rest frame members 18, 20, shows a back rest support surface curvature which substantially corresponds with the vertebral curvature at least in a region which corresponding with the lumbar region and a transition region which is formed by a lower part of the thoracic region and an upper part of the lumbar region.

The effects and advantages of the backrest 10 have been described in the summary section and these effects and advantages are inserted here by reference.

In an embodiment, the first pair of lateral segments 34a, 34b connected to the first central region segment 26 are connected at a height of the lateral back rest frame members 18, 20 so that the first central region segment 26 supports the back of the seated person in the transition region of the vertebral column formed by the lower part of the thoracic region and the upper part of the lumbar region.

In this embodiment, the transition region is supported by a dedicated part of the central region 26, 28, 30 and lateral segments 34a, 34b, 36a, 36b, 38a, 38b namely the first central region segment 26 and the first pair of lateral segments 34a, 34b. These parts may be dimensioned or adjusted such that the transition region of the seated person is optimally supported. With setting the height of the first central region segment 26 and associated lateral segments 34a, 34b such that it matches the position of the transition region of the vertebral column of the seated person, support of said part of the vertebral column is improved.

In an embodiment, the second pair of lateral segments 36a, 36b which are connected to the second central region segment 28 are connected at a height of the lateral back rest frame members 18, 20 so that the second central region segment 28 supports the back of the seated person in a lower part of the lumbar region.

In this embodiment the lower part of the lumbar region is supported by a dedicated part of the central region 26, 28, 30 and lateral segments 34a, 34b, 36a, 36b, 38a, 38b namely the second central region segment 28 and the second pair of lateral segments 36a, 36b. These parts may be dimensioned or adjusted such that the lower part of the lumbar region is optimally supported. With setting the height of the second central region segment 28 and associated lateral segments 36a, 36b such that it matches the position of the lower part of the lumbar region of the seated person, support of said part of the vertebral column is improved.

With this embodiment in combination with the previous embodiment in which the height of the first central region segment 26 is set to the transition region, firm support is given to the entire critical support region of the vertebral column of the seated person.

In an embodiment, the at least four lateral segments 34a, 34b, 36a, 36b, 38a, 38b comprise a third pair of lateral segments 38a, 38b connected to a third central region segment 30.

Apart from the above described critical support regions of the vertebral column, other parts may be supports as well. The third central region segment 30 may e.g. support an upper part of the thoracic region, of which examples are shown in the figures.

In an embodiment, the third pair of lateral segments 38a, 38b which are connected to the third central region segment 30 are connected at a height of the lateral back rest frame members 18, 20 so that the third central region segment 30 supports the back of the seated person in an upper part of the thoracic region and optionally a lower part of the cervical region.

In this embodiment the upper part of the thoracic region and optionally a lower part of the cervical region are supported by a dedicated part of the central region 26, 28, 30 and lateral segments 34a, 34b, 36a, 36b, 38a, 38b namely the third central region segment 30 and the third pair of lateral segments 38a, 38b. These parts may be dimensioned or adjusted such that the upper part of the thoracic region and optionally a lower part of the cervical region are optimally supported. With setting the height of the third central region segment 30 and associated lateral segments 38a, 38b such that it matches the position of the upper part of the thoracic region of the seated person, support of said part of the vertebral column is improved.

In an embodiment, of which no example is shown in the figures, the at least four lateral segments 34a, 34b, 36a, 36b, 38a, 38b comprise a fourth pair of lateral segments connected to a fourth central region segment. The fourth pair of lateral segments which are connected to the fourth central region segment may be connected at a height of the lateral back rest frame members 18, 20 so that the fourth central region segment supports the back of the seated person in the sacral region.

Similar to the first to third central region segments 26, 28, 30, the fourth central region segment may support a determined part of the vertebral column of the seated person. For support of the sacral region, the fourth central region segment should be more to the dorsal side with respect to the part which supports the lumbar region, in order to accommodate the buttocks of the seated person.

In an embodiment, of which an example is shown in figures 1-3, each lateral segment 34a, 34b, 36a, 36b, 38a, 38b of the back support structure 22 comprises a patch of non-elastic, flexible sheet material. The central region 26, 28, 30 comprises at least one patch of non-elastic, flexible sheet material, wherein the lateral patches 34 are connected to the central region 26, 28, 30 by seams.

The patches may be stitched or sewn together. Alternatively, the connection may be realised with adhesive or by weld seals. The patches form different surfaces which may be fitted together and be connected to the lateral frame members 18, 20 in such a way that the back support structure 22 has a three-dimensional shape. This three-dimensional shape may be pre-bent in order to follow the three-dimensional shaped contours of the vertebral column of the seated person.

Each of the first and second segments 26, 28 of the central region may comprise a patch of non-elastic, flexible sheet material, wherein an upper edge of the patch forming the second segment 28 is connected by a seam to a lower edge of the patch forming the first segment 26. Also, the third segment 30 of the central region may comprises a patch of non-elastic, flexible sheet material, wherein the lower edge of the patch forming the third segment 30 is connected by a seam to an upper edge of the patch forming the first segment 26. Furthermore, the fourth segment of the central region may also comprise a patch of non-elastic, flexible sheet material, wherein an upper edge of the patch forming the fourth segment is connected by a seam to a lower edge to a lower edge of the patch forming the second segment 28.

By each of the first and second central region segments 26, 28, and optionally the third and fourth central region segments 30 having their own patch, each of these segments 26, 28, 30 is clearly defined. Also, the seam between the patches of the first and second central region segments 26, 28, between the patches of the first and third central region segments 26, 30,

and between the patches of the second and fourth central region segments 30, may provide a flexible edge or ridge between the two respective segments 26, 28, 30 This may provide that the shape of the central region 26, 28, 30 may be better tailored to a user so as to follow the curves of the vertebral column of the seated person more closely. The seams between the patches forming the first central region segment 26, the second central region segment 28, and the optional third central region segment 30, and the optional fourth central region segment (not shown) may provide some additional stiffness relative to the flexible sheet material which may promote the form stability of the central region of the back support structure 22.

In an alternative embodiment, the central region 26, 28, 30 may be integrally formed from a single patch of non-elastic, flexible sheet material, as is shown in figures 1-3. Thus, production of the back support structure 22 according to this embodiment may be more cost effective.

In an embodiment, of which an example is shown in figures 4-6, the back support structure 22 is formed from a single piece of substantially non- elastic, flexible sheet material.

With this implementation of the back support structure 22 no seams are necessary at all and production costs may be further reduced relative to an embodiment having a plurality of patches which are connected by seams.

In an embodiment, the back support structure 22 may be provided with stiffeners.

Stiffeners may provide stiffness to the non-elastic, flexible sheet material of the back support structure 22, so that flexing of the material is locally prevented or at least reduced.

The stiffeners may be helpful to define and maintain the three- dimensional curved shape of the back rest support surface 24.

In an embodiment, the rigid back rest frame 16 may be collapsible from a working condition to a collapsed condition. In the working condition the lateral back rest frame members 18, 20 are spaced apart from each other at a first distance. In the collapsed condition the lateral back rest frame members 18, 20 are moved towards each other and the back support structure 22 is folded in a collapsed condition.

The backrest 10 in a collapsed condition of the back support structure 22, may take up less space than in the working condition. This facilitates storing of the backrest 10 when it is not used. Thus, the backrest 10 may be part of a collapsible wheelchair 12. The wheelchair 12 with the collapsible backrest 10 may be brought in a collapsed state without having to disassemble the backrest 10 from the other parts of the wheelchair 12.

The collapsibility of the back support structure 22 may be provided by hinges in a cross member 78 which connects the lateral back rest frame members 18, 20, as can been seen in the figures.

In an embodiment, each lateral back rest frame member 18, 20 is composed of an upper lateral back rest frame member part and a lower lateral back rest frame member part. The upper and the lower lateral back rest frame member parts may be pivotable with respect to each other around a substantially horizontally extending pivot axis. The lateral segments of the first pair of lateral segments 34a, 34b are each connected to the upper lateral back rest frame member part associated with that lateral segment 34a, 34b, and the lateral segments of the second pair of lateral segments 36a, 36b are each connected to the lower lateral back rest frame member part associated with that lateral segment 36a, 36b. The lower lateral back rest frame member parts can be fixed in various pivot positions to support the buttocks of the seated person.

In this way the second central region segment 28, which supports the lower part of the lumbar region, is pivotable with respect to the first central region segment 26, which supports the transition region of the vertebral column. The first central region segment 26 may be fixed relative the seated person to provide optimal support for the vertebral column of the seated person, while the second central region segment 28 may be adjusted to accommodate different sizes of buttocks.

When being part of a chair or wheelchair 12, the upper lateral back rest frame member parts may e.g. be non-movably attached to a main frame of the chair 12. The lower lateral back rest frame member parts may then be pivotable with respect to the main frame of the chair 12.

In an embodiment, of which an example is shown in figure 3, the first central region segment 26 may, in the loaded condition, extend in a plane that encloses an angle with a horizontal plane in a range between 100° and 130°, preferably approximately 115°.

Such an angle provides an optimal sitting angle for supporting the back of the seated person.

In an embodiment, the lateral back rest frame members 18, 20 each comprises one or more rigid, bended back rest frame tubes.

Tubes are both rigid and relatively light and can be easily shaped along a curve in a bending machine. They are strong enough to give the required support, and also light enough to be able to handle the back rest 10, e.g. as part of a wheelchair 12.

In an embodiment, the outer edges of the lateral segments 34a, 34b, 36a, 36b, 38a, 38b may be provided with a cord. Each lateral back rest frame member 18, 20 may comprise a groove 82 extending along the length of the lateral back rest frame member 18, 20 and having a groove opening extending along the length of the groove 82 with a width which is smaller than an outer diameter of the cord. The cord is mounted in the groove 82 for connecting the outer edges of the lateral segments to an associated one of the lateral back rest frame members 18, 20.

The outer edges of the lateral segments 34a, 34b, 36a, 36b, 38a, 38b may be provided with at least two seam tunnels in which the cord is selectively accommodated, wherein the tunnel in which the cord is accommodated is mounted in the groove 82 for connecting the outer edges of the lateral segments 34a, 34b, 36a, 36b, 38a, 38b to an associated one of the lateral back rest frame members 18, 20.

The cord and groove 82 combination provide an easy way to attached and detach the back support structure 22 to and from the back rest frame 16. The cord may be pulled though the groove 82 in a longitudinal direction. When in a loaded condition of the backrest support structure 22, the cord will remain in the groove 82 because it cannot pass the groove opening. By having multiple seam tunnels the cord may be selectively placed in any of these. In this way the width of the back support structure 22 may be chosen and adapted to the size and shape of the seated person. Thus, the curvature of the backrest support structure 22 in a horizontal cross-section may be varied so as to provide a more flat or a deeper, i.e. more concave back rest support structure 22. .

In an embodiment, of which an example is shown in figure 6, each lateral segment 34a, 34b, 36a, 36b, 38a, 38b of a pair of segments may be associated with a strap 80 for setting the lateral width of each one of the lateral segments 34a, 34h, 36a, 36b, 38a, 38b of the pair of lateral segments.

The straps 80 may serve to adjust the width of the back support structure 22. Similar to the multiple tunnel seams, the straps 80 may be used vary the shape of the back support structure 22 from flat to deep and vice versa as explained in the previous embodiment.

Each lateral segment of the first pair of lateral segments 34a, 34b may be associated with two straps 80 each having only a discrete number of setting lengths, e.g. two setting lengths. Each lateral segment of the second and the optional third and fourth lateral segments 36a, 36b, 38a, 38b may be each associated a single strap 80 of which the length is settable along a continuous range.

When adjusting the back rest support structure 22 for a user, the straps 80 of the first lateral segments 34a, 34b only have a discrete number of setting lengths, should be adjusted first. Thus, the angle of the first central region segment 26 relative to the horizontal may be varied in just two or three positions and the curvature in a horizontal cross-sectional plane at the level of the first central region segment 26 may be varied between two variants, namely flat and deep, i.e. more concave than in the flat condition. After setting the straps 80 of the first pair of lateral segments 34a, 34b, the straps 80 of the other lateral segments 36a, 36b, 38a, 38b can then be adjusted afterwards. This means that the most important part for supporting the back of the seated person, namely the first central region segment 26, connected to the first pair of lateral segments 34a, 34b, is adjusted first without being hindered by the setting of the other straps 80. After positioning and orienting the first central region segment 26 at the right height and angle, the main seating position for the user is defined. Subsequently, the amount of lateral support may be varied by tensioning or loosening the straps 80 of the second and the optional third and fourth pairs of lateral segments 36a, 36b, 38a, 38b. Thus, an optimal support for the back of the seated person may be ensured.

In an embodiment, a lateral width of the back support structure 22 may be variable by means of three or more zippers halves extending parallel and with which the width of the lateral segments 34a, 34b, 36a, 36b, 38a, 38b or, alternatively, the central region 26, 28, 30 may be selectively settable.

The user can select two zipper halves to zip up. By selecting which zipper halves to zip up, the width of the lateral segments 34a, 34b, 36a, 36b, 38a, 38b or, alternatively, the central region 26, 28, 30 is set. The effects are similar to effects described with reference to the above mentioned embodiment in which the cord is selectably placed in one of the multiple of seam tunnels.

The invention also relates to a chair 12 for supporting a seated person. The chair 12, of which an example is shown in the figures, may include wheels so as to form a wheelchair 12. The chair 12 comprises the backrest 10 according to the invention as well as a seat.

The effects and advantages of the chair 12 have been described in the summary section and these effects and advantages are inserted here by reference.

In an embodiment, the seat 14 of the chair mentioned above may comprise a rigid seat frame 42 and a seat support structure 48 comprising substantially non-elastic, flexible sheet material. The rigid seat frame 42 has two opposite lateral seat frame members 44, 46. The lateral seat frame members 44, 46 are shaped along a lateral seat frame curvature which, when viewed from a lateral side, substantially corresponds to a buttock curvature when viewed in cross section along a sagittal plane. The seat support structure 48 defines, in a loaded condition, i.e. when a person is resting with his buttocks on the seat 14, a form-stable seat support surface

50.

The seat support structure 48 comprises a central seat region 52, 54 and at least four lateral seat segments 58a, 58b 60a, 60b. The central seat region 52, 54 has two opposite lateral edges 56 and a front and a rear edge. Each lateral seat segment 58a, 58b 60a, 60b of the at least four lateral seat segments 58a, 58b 60a, 60b has an inner and an outer lateral edge. Each lateral seat segment 58a, 58b 60a, 60b is connected with its inner lateral edge with the lateral edge 56 of the central seat region 52, 54 and with its outer edge with a lateral seat frame member 44, 46. The lateral seat segments 58a, 58b 60a, 60b are arranged in pairs of lateral seat segments 58a, 58b 60a, 60b which are connected to the central seat region 52, 54 at directly opposite parts of the lateral edges 56 of the central seat region 52,

54. A first pair of lateral seat segments 58a, 58b is connected to a first central seat region segment 52 and a second pair of lateral seat segments

60a, 60b is connected to a second central seat region segment 54. The form stable seat support surface 50 has a three-dimensionally curved shape of which a cross-sectional view in the sagittal plane, i.e. a substantially vertical plane which is centrally positioned between the two lateral seat frame members, shows a seat support surface curvature which substantially corresponds with the buttocks curvature, wherein the three-dimensionally curved seat support surface substantially corresponds to the three- dimensionally curved, anatomical shape of the buttocks of the seated person.

It should be noted that the invention also relates to a chair having the above-described seat 14 but a different type of backrest than the one claimed in claims 1-24. In other words, the chair 12 according to claim 27 may applied independently from the backrest according to the invention.

The seat support structure 48 is similar to the back support structure 22. The effects and advantages of the back support structure 22 mentioned in this disclosure, apply mutatis mutandis to the seat support structure 48. Thus, a chair 12 is provided with a stably supporting seat 14 which has the additional advantage that the chair may be collapsible.

In an embodiment the first central seat region segment 52 substantially extends in a plane that includes an angle with a horizontally extending plane in the range of 5° to 15°, more preferably 12°.

Such an angle provides an optimal sitting angle for supporting the buttocks and/or tights of the seated person. In an embodiment, the seat 14 additionally comprises a front part comprising a front seat frame 62 and a front seat support structure 80. The front seat frame 62 has two opposite lateral front seat frame members 64, 66, of which the position is adjustable relative to the backrest 10 and the rigid seat frame 42 in a front and rear direction. The front seat support structure 68 comprises substantially non-elastic, flexible sheet material.

The front seat support structure 68 defines, in a loaded condition, i.e. when a person is resting with his buttocks on the seat, a form-stable front seat support surface 70. The front seat support structure 68 comprises a central front seat region 72 and at least two lateral front seat segments 76a, 76b. The central front seat region 72 has two opposite lateral edges 74 and a front and a rear edge. Each lateral front seat segment 76a, 76b of the at least two lateral front seat segments 76a, 76b has an inner and an outer lateral edge. Each lateral front seat segment 76a, 76b is connected with its inner lateral edge with the lateral edge 74 of the central front seat region and with its outer edge with a lateral front seat frame member.

A rear region of the front seat support structure 68 overlaps with a front region of the seat support structure 48. The total depth of the seat support structure 48 and the front seat support structure 68 is adjustable by adjusting the position of the front seat frame 62 relative to the rigid seat frame 42 so as to match the depth of the seat 14 to the length of the thigh of the seated person.

The various embodiments which are described above may be used implemented independently from one another and may be combined with one another in various ways. The reference numbers used in the detailed description and the claims do not limit the description of the embodiments nor do they limit the claims. The reference numbers are solely used to clarify by referring to the non-limiting example in the figures.

Legend 10 — backrest 12 — (wheel)chair 14 — seat 16 — back rest frame 18, 20 — lateral back rest frame member 22 — back support structure 24 — back rest support surface 26 — first central region segment 28 — second central region segment 30 — third central region segment 32 — lateral edge (of central region) 34a, 34b, 36a, 36b, 38a, 38b — lateral segment 42 — seat frame 44, 46 — lateral seat frame member 48 — seat support structure 50 — seat support surface 52 — first central seat region segment 54 — second central seat region segment 56 — lateral edge (of central seat region) 58a, 58b 60a, 60b — lateral seat segment 62 — front seat frame 64, 66 — lateral front seat frame member 68 — front seat support structure 70 — front seat support surface 72 — central front seat region 74 — lateral edge (of central front seat region) 76a, 76b — lateral front seat segment 78 — cross member

80 — strap 82 — groove

Claims

Conclusions

1. Backrest (10) for supporting the back of a seated person, the person having a vertebral column provided with a sacral region, a lumbar region defined by lumbar vertebrae (L1-L5), a thoracic region defined by thoracic vertebrae (T1-T12) and a cervical area defined by cervical vertebrae (C1-C7), and where the vertebral column has a vertebral curvature as seen in a cross section over a sagittal plane, where the back support comprises: e a rigid back support frame (16) provided with two opposing lateral back support frame members (18, 20), the lateral back support frame members (18, 20) being formed along a lateral back support frame curvature which, viewed from a lateral side, generally conforms to the spinal curvature at least in an upper portion of the lumbar region and a lower part of the thoracic region; and e a back support structure (22) comprising a substantially non-elastic, flexible sheet material, wherein the back support structure (22), in a loaded position, for example when a person rests with his back against the back support (10), has a form-retaining back support surface (24 ), wherein the back support structure (22) comprises: o a central region (26, 28, 30) having two opposing lateral edges (32) and an upper and a lower edge; o at least four lateral segments (34a, 34b, 36a, 36b, 38a, 38b), each lateral segment (34a, 34b, 36a, 36b, 38a, 38b) having an inner and outer lateral border, each lateral segment ( 34a, 34b, 36a, 36b, 38a, 38b) is connected with its inner lateral edge to the lateral edge (32) of the central region (26, 28, 30) and with its outer lateral edge to an associated back support frame member ( 18, 20) of the lateral back support frame members (18, 20), the lateral segments (34a, 34b, 36a, 36b, 38a, 38b) being arranged in pairs of lateral segments connected to the central region (26, 28, 30) at the same height on the opposite lateral edges (32) of the central region (26, 28, 30), with a first pair of lateral segments (34a, 34b) connected to a first central region segment ( 26) and a second pair of lateral segments (36a, 36b) 1s connected to a second central region segment (28); wherein the back support surface (24) in its loaded position has a rigid, three-dimensionally curved shape having a cross-section in the sagittal plane, i.e. a substantially vertical plane positioned centrally between the two lateral back support frame members (18, 20), has a back support surface curvature substantially corresponding to the vertebral curvature at least in a portion corresponding to the lumbar region and a transition region formed by a lower portion of the thoracic region and an upper portion of the lumbar region.

The back support of claim 1, wherein the substantially non-elastic, flexible sheet material of the back support structure (22) is selected from the group consisting of canvas, cloth, and film.

The backrest of claim 1 or 2, wherein the first pair of lateral segments (34a, 34b) connected to the first central

region segment (26) 1s connected at a height of the lateral back support frame members (18, 20) such that the first central region segment (26) supports the seated person's back in the transition region of the spine being formed through the lower part of the thoracic region and their upper part of the lumbar region.

The back support according to any one of claims 1-3, wherein the second pair of the lateral segments (36a, 36b) connected to the second central region segment (28) are connected at a height of the lateral back support frame elements (18,20) such that the second central region segment (28) supports the seated person's back in a lower portion of the lumbar region.

The back support according to any one of the preceding claims, wherein the at least four lateral segments (34a, 34b, 36a, 36b, 38a, 38b) comprise a third pair of lateral segments (38a, 38b), the third pair of lateral segments segments (38a, 38b) is connected to a third central region segment (30).

The back support according to the combination of claims 3, 4 and 5, wherein the third pair of lateral segments (38a, 38b) connected to the third central region segment (30) is connected at a height of the lateral back support frame elements (18, 20) such that the third central region segment (30) supports the seated person's back in an upper part of the thoracic region and optionally in a lower part of the cervical region.

The back support according to any one of the preceding claims, wherein the at least four lateral segments (34a, 34b, 36a, 36b, 38a, 38b) comprise a fourth pair of lateral segments, the fourth pair of lateral segments being connected to a fourth central area segment.

The back support of claim 7 in combination with claim 6, wherein the fourth pair of lateral segments connected to the fourth central region segment 1 are connected at a height of the lateral back support frame members (18, 20) such that the fourth central region segment supports the seated person's back in the sacral region.

The back support of any preceding claim, wherein each lateral segment (34a, 34b, 36a, 36b, 38a, 38b) of the back support structure (22) comprises a patch of non-elastic, flexible sheet material, the central region ( 26, 28, 30) comprises at least one patch of non-elastic, flexible sheet material, the lateral patches (34) being connected to the central region (26, 28, 30) by seams.

The back support of claim 9, wherein the first and second segments (26, 28) of the central region each comprise a patch of non-elastic, flexible sheet material, an upper edge of the patch forming the second segment (28) is seamed to the lower edge of the patch forming the first segment (26).

The back support of claim 9 in combination with claim 6, wherein the third segment (30) of the central region comprises a patch of non-elastic, flexible sheet material, the lower edge of the patch containing the third segment (30) forms with a seam connected to an upper edge the patch that forms the first segment (26).

The back support of claim 11 in combination with claim 8, wherein the fourth segment of the central region comprises a patch of non-elastic, flexible sheet material, an upper edge of the patch forming the fourth segment being seamed with a lower border the patch forming the second segment (28).

The back support of claim 9, wherein the central region (26, 28, 30) is formed integrally from a single patch of non-elastic, flexible sheet material.

The back support of any preceding claim, wherein the back support structure (22) is formed from a single piece of substantially non-elastic, flexible sheet material.

The back support according to any one of the preceding claims, wherein the back support construction (22) is provided with stiffness-enhancing elements.

The back support according to any one of the preceding claims, wherein the rigid back support frame (16) is collapsible from a working position to a folding position, wherein in the working position the lateral back support frame members (18, 20) are spaced apart by a first distance, wherein in the collapsed state the lateral back support frame members (18, 20) have moved towards each other and the back support structure (22) has been folded into a fold down position.

The back support according to any one of the preceding claims, wherein each lateral back support frame member (18, 20) consists of an upper lateral back support frame member portion and a lower lateral back support frame member

member portion, the upper and lower lateral back support frame member portions being pivotable relative to each other about a substantially horizontally extending pivot axis, the lateral segments of the first pair of lateral segments (34a, 34b) each being connected to the upper lateral back support frame member portion associated with said lateral segment (34a, 34b), and wherein the lateral segments of the second pair of lateral segments (36a, 36b) are each connected to the lower lateral backrest frame member portion associated with said lateral segment (36a, 36b), wherein the lower lateral back support frame members can be fixed in different pivoting positions to support the buttocks of the seated person.

The backrest according to any one of the preceding claims, wherein the first central region segment (26) in the loaded condition extends in a plane that includes an angle with a horizontal plane in a range between 100° and 130°, at preferably about 115°.

The back support according to any of the preceding claims, wherein the lateral back support frame members (18, 20) each comprise one or more rigid, curved back support frame tubes.

The back support according to any one of the preceding claims, wherein the outer edges of the lateral segments (34a, 34b, 36a, 36b, 38a, 38b) are provided with a tendon, and each lateral back support frame member (18, 20) has a groove (82) extending the length of the lateral back support frame member (18, 20) and having a groove opening extending the length of the groove (82) having a width less than an outside diameter of the tendon, the tendon being secured in the groove (82) for connecting the outer edges of the lateral segments to an associated lateral back support frame member of the lateral back support frame members (18, 20).

The back support of claim 20, wherein the outer edges of the lateral segments (34a, 34b, 36a, 36b, 38a, 38b) are provided with at least two seam tunnels that receive the tendon of choice 1s, the tunnel in which the tendon is included is secured in the groove (82) for connecting the outer edges of the lateral segments (34a, 34b, 36a, 36b, 38a, 38b) to an associated lateral back support frame member (18, 20).

The back support according to any one of the preceding claims, wherein each lateral segment (34a, 34b, 36a, 36b, 38a, 38b) of a pair of segments is associated with a tension strap (80) for adjusting a lateral width of each of the lateral segments (34a, 34b, 36a, 36b, 38a, 38b) of the pair of lateral segments.

The backrest of claim 22, wherein each lateral segment of the first pair of lateral segments (34a,34b) is associated with two tension straps (80) having only a discrete number of adjustment lengths, e.g. two m adjust lengths, with each lateral segment of the second and optionally third and fourth lateral segments (36a, 36b, 38a, 38b) include a single tension strap (80) adjustable in length over a continuous range.

The back support according to any one of the preceding claims, wherein a lateral width of the back support structure (22) is adjustable by means of three or more zipper halves extending in parallel and by which the width of the lateral segments (34a, 34b, 36a, 36b , 38a, 38b) or, alternatively, the central region (26, 28, 30) is optionally adjustable.

25. A chair (12) for supporting a seated person, comprising: - a seat (14); and - the backrest (10) according to any one of claims 1-24.

The chair of claim 25, wherein the chair (12) includes wheels to form a wheelchair.

A chair, optionally according to claim 25 or 26, wherein the chair has a seat (14) comprising: e a rigid seat frame (42) comprising two opposing lateral seat frame members (44, 46), the lateral seat frame members being elements (44, 46) are formed along a lateral seat frame curvature which, when viewed from a lateral side, generally corresponds to a buttocks curvature when viewed in a section through a sagittal plane; and e a seat support structure (48) comprising a substantially non-elastic, flexible sheet material, the seat support structure (48), in a loaded position, e.g. ), wherein the seat support structure (48) comprises: o a central seat region (52, 54) having two opposing lateral edges (56) and a front and a back edge; o at least four lateral seat segments (58a, 58b, 60a, 60b), each lateral seat segment (58a, 58b, 60a, 60b) having an inner and outer lateral edge, each lateral seat segment (58a, 58b, 60a, 60b) connected with its inner lateral edge to the lateral edge (56) of the central seat area (52, 54) and with its outer lateral edge to a lateral seat frame member (44, 46), the lateral seat segments (58a, 58b, 60a, 60b) are arranged in pairs of lateral seat segments (58a, 58b, 60a, 60b) connected to the central seat region (52, 54) on immediately opposite lateral edges (56) of the central seat region (52, 54), a first pair of lateral seat segments (58a, 58b) connected to a first central seat area segment (52) and a second pair of lateral seat segments (60a, 60b) connected to a second central seat area segment (54); wherein the rigid seat support surface (50) has a three-dimensional curved shape having a cross-section in the sagittal plane, i.e. a substantially vertical plane centrally located between the two lateral seat frame members, having a seat support surface curvature substantially corresponding to the buttocks curvature , wherein the three-dimensionally curved seat support surface substantially corresponds to the three-dimensionally shaped, anatomical shape of the buttocks of the seated person.

The chair according to claim 27, wherein the first central seat region segment (52) extends substantially in a plane that includes an angle with a horizontal plane in the range of 5° to 15°, preferably 12°.

The chair of claim 27 or 28, wherein the seat (14) also includes a front portion, the front portion comprising:

e a front seat frame (62) comprising two opposing lateral front seat frame members (64, 66), the position of which is adjustable in a forward and rearward direction relative to the backrest (10) and the rigid seat frame (42); and e a front seat support structure (68) comprising a substantially inelastic, flexible sheet material, the front seat support structure (68), in a loaded position, e.g. seat support surface (70), wherein the front seat support structure (68) comprises:

o a central front seat area (72) having two opposing lateral edges (74) and a front and a back edge; and o at least two lateral front seat segments (76a, 76b), each lateral front seat segment (76a, 76b) having an inner and outer lateral edge, each lateral front seat segment (76a, 76b) having its inner lateral edge 1s connected to the lateral edge (74) of the central front seat area and with its outer lateral edge with a lateral front seat frame member,

wherein a rear region of the front seat support structure (68) overlaps with a front region of the seat support structure (48), the total depth of the seat support structure (48) and the front seat support structure (68) being adjusting pair by adjusting the position of the front seat frame (62) relative to the rigid seat frame (42) to adjust the depth of the seat (14) to the length of the seated person's upper leg.