EP1083809A1

EP1083809A1 - Anatomic seat comprising a lumbar support and a seat with at least one depression for the ischia

Info

Publication number: EP1083809A1
Application number: EP99923714A
Authority: EP
Inventors: Richard Chene; Dominique Delamour; Olivier Rodi
Original assignee: CGEA Transport SA; R & D Industries A Responsabilite Ltee Ste
Current assignee: CGEA Transport SA; R & D Industries A Responsabilite Ltee Ste
Priority date: 1998-06-11
Filing date: 1999-06-10
Publication date: 2001-03-21
Also published as: WO1999063868A1; FR2779622A1; AU4048699A; FR2779622B1

Abstract

The invention relates to a seat comprising a combined lumbar support (108) and seat (202) with at least one depression that is adapted in such a way that it can serve as a support for the ischia of the user. Said depression can consist of a cavity (3, 103) with a curved edge, such as a bean-shaped cavity, or can be created by a shoulder (10) arranged inside the thickness of said seat (202). The lumbar support (108) can be formed by a support structure with an outer surface that is turned towards the user, whereby said outer surface has a concave profile on a horizontal plane and a convex profile on a vertical plane.

Description

Anatomical seat comprising a lumbar support and a seat having at least one depression for ischia.

The present invention relates to an anatomical seat. It is known that people forced to occupy a prolonged sitting position, for example in the context of their work, end up having a slackening of the back. This is notably due to the fact that, when these people make the effort to sit in a correct anatomical position, most of their body mass is supported on the bones of their pelvis, and more precisely at the level of the ischions, that is to say on a relatively small volume of flesh. This quickly leads to a feeling of pain that the person tends to relieve by tilting his pelvis backwards, a tilting which results in a sliding of the pelvis and thighs forward and a sagging of the trunk.

In the prior art, cushioning materials or cushioning devices have been used to provide comfortable support to the ischia, which has delayed the onset of pain sensations. However, in addition to the fact that these materials and devices considerably increase the cost of the seats which they equip, they do not encourage the user of the seat to adopt and maintain an anatomically correct sitting position, insofar as it is not sufficiently propped, nor seated comfortably, on the known seats.

The invention aims to remedy the aforementioned drawbacks of the prior art by proposing a new type of seat which encourages a user to adopt, and allows him to maintain for several hours, a comfortable sitting position, without pain or loss of sound. back, which is both inexpensive and simple to build.

This object is achieved, according to the invention, by a seat comprising, in combination, a lumbar support and a seat having at least one depression adapted to serve as support for the ischia of a user. It is understood that the lumbar support allows the seat according to the invention to follow the natural curvature (moderate lordosis) of the spine of a user, so as to allow him to take a comfortable position and avoid any back pain inevitably linked to prolonged sitting in an anatomically unfavorable posture. For its part, the depression provided in the seat of the seat according to the invention makes it possible to respect the anatomical difference in level between the posterior surface of the thighs and the lower part of the pelvis / ischial assembly and thus to transfer and distribute the load of the body mass on a large surface, located under the thighs and the gluteal mass. In addition, this depression constitutes an anti-sliding structure providing an abutment anterior to the base of the ischial / coccyx triangle. This stop prevents slipping of the ischia and, in doing so, unwanted slouching of the sitting posture.

Advantageously, the front edge of said depression may be curved, the center of its mean radius of curvature being situated towards the rear part of the seat. The center of the arc formed by the anterior edge of the depression will then preferably correspond to the vertex opposite the base of an isosceles triangle contained in a horizontal plane and the base of which is formed by the straight line connecting the locations normally provided for the user's bones, said vertex being located in the vertical plane tangent to the lumbar support. These locations are adjacent to the front edge of said depression and usually spaced about 15 cm from each other, the line segment which connects them being centered transversely to the seat. Thus, in a first embodiment of the invention, said depression is a cavity with a curved edge advantageously having the shape of a bean and which can for example have a length of approximately 20 cm, a width of approximately 5 cm and a depth of at least about 8 mm. The aforementioned anti-slip structure thus has the shape of an ischial fossa.

In a second embodiment of the invention, said depression is created by a shoulder formed in the thickness of the seat cushion. The aforementioned anti-slip structure thus has the form of an ischial step, which can for example have a height of between approximately 8 mm and 35 mm, preferably approximately 20 mm.

Preferably, to ensure even better comfort for the user and to offer him, in particular, a certain latitude of movement on the seat, in translation as in rotation, the posterior edge of said ischial step, which corresponds to the anterior edge of said depression, may have a curvature similar to that of the first embodiment of the invention. In the same vein, the lumbar support may be formed of a support structure whose outer surface, facing the user, has a concave profile in a horizontal plane and convex in a vertical plane. These characteristics will be used particularly advantageously in a seat which is not intended to pivot, either for safety reasons, as is the case in vehicles, or for reasons of space, as is example the case behind certain sales counters. Advantageously, in the position of normal use of the seat, the distance, called the vertical distance of the depression, between the bottom of said depression and the horizontal plane normal to the vertical plane tangent to the lumbar support is approximately 18 to 22 cm, and the distance, called horizontal distance of the depression, between the anterior edge of said depression and said vertical plane is approximately 18 to 22 cm. In addition, said depression preferably has a length of at least about 15 cm, in the transverse direction of the seat, that is to say in a plane parallel to said vertical plane. These distances guarantee correct anatomical positioning of the user on the seat according to the invention, whatever its size, provided that it is between approximately 1.60 m and 2.0 m, and whatever its morphology. In addition, the horizontal and vertical distances of the depression make it possible to provide, in the seat, a posterior clearance adapted to receive the gluteal mass, which can be very variable from one individual to another. This release prevents the gluteus mass from being hindered by, or even simply in contact with, structural elements of the seat which would induce an advancement of the pelvis, thus initiating a phenomenon of slump.

Advantageously, the depression according to the invention is filled with a deformable material having elastic properties, such as a foam, of lower density than the seat. In addition, the seat may for example be coated with a non-slip material, which contributes to the maintenance of the pelvis and prevents the latter from slipping.

According to a preferred embodiment of the invention, applied to a seat of the type comprising a cover, of which a seat cushion-shaped portion and a back cushion-shaped portion, fitted to a seat structure, said depression is provided in the seat cushion portion and the lumbar support is provided in the back cushion portion.

The seat according to the invention can be fixedly mounted on a support, such as a substantially vertical partition or a base. In this case, the seat of the seat according to the invention may be more or less inclined relative to the vertical, depending on the height at which it is mounted above the ground, and the lumbar support will preferably always keep the same orientation and the same distance from the seat. Thus, the angle of inclination of the seat may vary from 100 °, for a chair type seat whose seat is mounted about 35 cm from the ground, to 88 ° for a seat offering support to the user. in the "sit-stand" position and whose seat is mounted about 85 cm from the ground. This angle of inclination will generally be 90 ° for a classic seat, the seat of which is located approximately 60 cm from the ground. As a variant, the seat of the seat according to the invention can be pivotally mounted between a position offering support to a normally seated user and a position providing support to a seated-standing user. In this latter variant, the seat according to the invention may advantageously include two depressions in the form of a cavity with a curved edge, which are respectively adapted to provide support for the user's ischia in the seated position and in the sit-stand position.

According to another aspect, the present invention relates to a cover comprising a portion forming a seat cushion intended to cover the seat of a seat structure and a dormant portion of a back cushion intended to cover the backrest of a seat structure, said seat portion having at least one depression adapted to serve as support for the ischions of a user and said back portion providing lumbar support to the user.

The cover according to the invention, or at least the "cushions" part of this cover, may advantageously be made of a material whose density and / or thickness are chosen from a range of values each of which corresponds to a range given user weight and it will preferably be offered with a wide choice of colors and materials. Thus, in practice, the cover may be offered for sale and manufactured according to European or American size standards defined for the making of clothing, so as to adjust the characteristics of the material to the body size of the user. The cover according to the invention may be available in a variety of models adaptable to different seat structures, or in a single model adaptable to a standard seat structure, specially designed.

The invention will be better understood, and its advantages will emerge more clearly in the light of the detailed description. following, taken in combination with the accompanying drawings in which: Figure 1 is a schematic view, in vertical section, showing the skeleton of a user seated on a seat according to a first embodiment of one invention; Figure 2 is a schematic view, in vertical section, of the seat illustrated in Figure 1; Figure 3 is a schematic view in vertical section, similar to Figure 2, of a seat according to a second embodiment of the invention; Figure 4 is a schematic perspective view of an office chair according to a third embodiment of the invention, combining the characteristics of the two previous embodiments; FIG. 4a illustrates a variant of the seat of the seat shown in FIG. 4; Figure 5 is a schematic exploded perspective view partially broken away of a seat according to a fourth embodiment of the invention; and Figure 6 is a schematic view from below showing a user seated on the seat illustrated in Figure 3, the various components of the seat being projected onto the underside of his seat. In the figures described below, identical reference numerals denote elements of identical structure and identical reference numerals, but increased by 100 or multiples of 100, denote similar structural elements. In addition, the adjectives "anterior (s)" and "posterior (e) (s)" denote elements considered in relation to the normal mode of use of the seat according to the invention. The same is true of the adverbs "horizontally" and "vertically". If we refer first to Figures 1 and 2, we see a seat 1 according to the first embodiment of the invention which, in the illustrated variant, is a public transport seat. The seat 1 consists of a rigid shell 13 to which a foam material 12 is fixed. An ischial fossa 3, which will be described more with reference to FIG. 4, is formed in the foam material 12, at the level of the 'seat 2 of seat 1, to receive the seat bones 5 of a passenger in the seated position (Figure 1). The seat 1 also has a backrest 6 on which a lumbar support 8 is provided (FIG. 2). The lumbar support 8 has an external surface 8a, turned towards the user, provided with a double profile combining, when observed according to arrow F, a concave profile (not visible in FIG. 2) in a horizontal plane parallel to the seat 2 and a convex profile in a vertical plane. This configuration of the lumbar support 8 offers a certain rotational freedom to the user, while ensuring good support of his spine, approximately at the level of his third lumbar.

Returning to the ischial fossa 3, it can be seen in FIG. 2 that it is positioned in such a way that its bottom 3 ′ is spaced vertically by a distance a of approximately

20 cm from the horizontal plane P _λ , normal to the vertical plane P ₂ tangent to the lumbar support 8, and its front edge 3 "is spaced horizontally by a distance b of about 20 cm from the vertical plane P _2. The ischial fossa 3 is filled with a resilient foam material, of lower density than the foam 12, which is illustrated in the compressed state in FIG. 1 and at rest in FIG.

Between the backrest 6 and the seat 2, the seat 1 comprises a thin curved part 9, the convex curvature of which is turned away from the user, thus providing in the seat 1 a rear clearance 7 intended to receive the buttocks of the user. We understand that the ischial fossa

3 allows the load of the body mass to be transferred and distributed over a large area, located under the thighs 4 and the gluteal mass 4 ′ (FIG. 1). The headquarters of Public transport vehicle according to the invention therefore allows the passenger to adopt and maintain a comfortable sitting position. The ischial fossa 3, associated with the lumbar support 8 and the posterior release 7 (FIG. 2), also induces and stimulates the straightening of the back of the passenger, without however imposing it, thus helping to combat slackening of the sitting posture.

FIG. 3 illustrates a seat 101 of a public transport vehicle according to another embodiment of the invention, in which the ischial pit 3 represented in FIGS. 1 and 2 is replaced by an ischial step 10 resulting from a difference thickness of the seat 102 of the seat 101 between the front seat part 102a, also called crural tile, which is intended to receive the front two-thirds of the thighs of a passenger, and the rear seat part 102b , also called buttock pane, which is intended to receive the posterior third of the thighs, as well as the buttocks, of the passenger. Specifically, the crural tile 102a is thicker than the gluteal tile 102b, which corresponds to the anatomical difference in level between the thighs and the buttocks of the seated user.

The function of the ischial step 10 is, in the same way as the ischial pit 3 illustrated in FIGS. 1 and 2, to distribute the body load in the sitting position and to prevent the user's pelvis from sliding forward, once his back has been straightened by the lumbar support 8.

As illustrated in FIG. 6, which is a view from below of the seat 101 represented in FIG. 3, the edge 10a of the ischial step 10, which constitutes the anterior edge of the depression formed in the seat 102 of the seat 101, defines , in a horizontal plane H, an arc 24 whose center C is located towards the rear part 102b of the seat 102. Precisely, the center C of this arc corresponds to the vertex opposite the base 25 of a triangle isosceles 26 contained in said horizontal plane H. The base 25 is formed by the line segment connecting the locations 27, 28 normally provided for the ischia of the user 29. The vertex C is located in the vertical plane P ₂ (Figure 3 ) tangent to the lumbar support 8. The locations 27, 28 are adjacent to the arc 24 and spaced about 15 cm from each other, the line segment 25 which connects them being centered transversely by relative to the seat 102. It can also be seen in FIG. 6 that the surface 8a of the lumbar support 8 of the seat 101 has a concave profile of concavity opposite to that of the arc of a circle 24 and substantially of the same radius of curvature R. Knowing that the pivot axis of the pelvic-lumbar complex is located at the center 30 of the circle (β) in which the triangle 26 is inscribed, it is understood that the illustrated configuration of the edge 10a of the ischial step 10 and of the dura 8a of the lumbar support 8 allows the user 29 to pivot er comfortably on seat 101.

It is understood that the embodiments illustrated in FIGS. 1 to 3 are given only by way of nonlimiting examples and that the invention can be applied to other types of public transport seats, such as as folding seats or seats of which the various constituent parts are formed of separate elements instead of being in one piece.

FIG. 4 illustrates an office chair 11 according to a third embodiment of the invention. The chair 11 illustrated comprises, in a manner known per se, a seat 202 mounted on a base 14 supported by castors, such as 16. The chair according to the invention further comprises a lumbar support 108, joined to the seat 202. The lumbar support 108 is convex in vertical section and concave in horizontal section. A posterior ischial fossa 3 and an anterior ischial fossa 103 are formed in the seat 202, each having a bean shape having a mean radius of curvature, the center of which is located towards the part posterior 202b of the seat 202. The pit 103 is located approximately 5 cm from the anterior edge of the seat 202 and spaced about 10 cm ± 2 cm from the pit 3. The two ischial pits 3.103 are each filled to the using a foam material of lower density than the material forming the seat 202.

In the variant of the invention shown, the seat 202 is slidably and pivotally mounted on the base 14, between a first position, illustrated in dotted lines, in which the chair 11 is adapted to offer support to a user in the normal sitting position and a second position, illustrated in solid lines, in which the chair 11 is adapted to offer support to a user in the sit-stand position. It is therefore understood that the ischial pit 3 is intended to be used in the first position, while the ischial pit 103 is intended to be used in the second position.

The chair illustrated in Figure 4 further comprises, at its front part 202a of the seat, an ischial step 10 identical to that shown in Figures 3 and 6, whose rear edge 10a is curved and merges, on a part of its length, with the anterior edge of the ischial fossa 103.

It will be noted that the bean shape of the ischial pits 3,103 and the curvature of the ischial step 10 allow a certain rotational freedom to the user, which is not essential in this type of swivel seat, but has a definite advantage for the supermarket cashiers working on seats without casters, whose activity requires continuous movements of their pelvis from left to right, and vice versa, as well as for people working behind tobacco counters, for example. These bean ischial pits are also useful in public transport seats such as the one shown in Figures 1 and 2. FIG. 4a illustrates a variant of the seat of the seat shown in FIG. 4, in which the crural tile or front part of the seat 402a is pivotally mounted, about 30 °, on the buttock tile or rear part of the seat 402b , between the position illustrated in dotted lines, in which the seat 402 provides support for a "sit-stand", and the position illustrated in solid lines, in which the seat 402 offers support for a seated user. The crural tile 402a is advantageously brought back and held by a return spring in the position shown in solid lines. In the variant illustrated in FIG. 4a, the pivoting of the crural tile 402a replaces that of the entire seat 202, as in FIG. 4, thus resulting in a less bulky chair and of simpler construction, and it makes furthermore unnecessary the provision of a second ischial pit, such as the pit 103 represented in FIG. 4.

Another embodiment of the seat according to the invention is illustrated in Figure 5. In this figure, we see a seat 21 comprising a cover 15 and a seat structure 17 adapted to each other. The cover 15 consists of a portion forming a seat cushion 302 and a portion forming a back cushion 106 from which flexible sections are projected, such as 18. In a similar manner to FIGS. 1, 2, 4 and 4a, an ischial pit 3 is formed in the seat cushion portion 302 of the cover 15, the center of the mean radius of curvature of said pit being located towards the rear part 302b of said seat portion. Specifically, the seat cushion portion 302 consists of a fabric or leather envelope, for example, which can be more or less thick and possibly profiled, as seen in Figure 5, and in which is inserted a molded seat part 23. The ischial pit 3 is formed in the molded part 23 and covered by the envelope. The cover 15 also includes a portion forming a back cushion 106 sewn to the portion forming a seat cushion 302, or in one piece with it, which defines, on the user side, a lumbar support 208 identical to that described with reference to FIG. 4. Again, the portion forming a back cushion 106 consists of a flexible envelope, more or less thick and capable of being profiled, into which a molded part 32 is inserted. The above-mentioned envelope is closed using a piece of self-gripping material , such as a Velcro® strip 31. For its part, the seat structure 17 is simply constituted, in the schematic embodiment illustrated, of a seat 20 on which a backrest 19 and four feet 22 are mounted. It is understood, however, that the seat structure could have any other suitable shape, such as that of an armchair, a relaxation seat and the like. As a variant, the seat structure 17 could take the form of a bench seat, in which case the cover 15 would advantageously include as many ischial fosses, such as 3, and lumbar supports, such as 208, as the number of seats provided on said bench.

The cover 15 can be fixed to the seat structure 17 by any means known to those skilled in the art, such as knots joining the sides, such as 18, of the cover.

It is understood that the invention is not limited to the embodiments described above by way of examples and that it can equally well be applied to car seats, chairs for the disabled, adapted seats to the arrangement of maritime or air vehicles for the public transport of persons, such as folding seats or tilting seats, garden chairs, and the like.

In addition, in its application to the layout of public transport, the seat according to the invention may be made of a vibration-absorbing material or contain a vibration-damping device, or it may be connected to the vehicle by a such device. These devices, known to one skilled in the art, may for example comprise a leaf spring, a gas shock absorber cylinder, a hydraulic shock absorber cylinder, and the like.

Claims

1. Seat characterized in that it comprises, in combination, a lumbar support (8; 108; 208) and a seat (2; 102; 202; 302; 402) having at least one depression (3; 103) suitable for serve as support for the ischions (5) of a user.

2. Seat according to claim 1, characterized in that in the position of normal use of the seat, the distance, said vertical distance (a) of the depression, between the bottom (3 ') of said depression (3; 103) and the horizontal plane (P _x ) normal to the vertical plane (P ₂ ) tangent to the lumbar support (8; 108; 208) is approximately 18 to 22 cm, the distance, called horizontal distance (b) of the depression between the anterior edge (3 ") of said depression (3; 103) and said vertical plane (P ₂ ) is about 18 to 22 cm and said depression (3; 103) is preferably a length of at least about 15 cm, in the transverse direction of the seat (2; 102; 202; 302; 402), extending in a plane parallel to said vertical plane (P ₂ ).

3. Seat according to claim 1 or 2, characterized in that the front edge (3 ") of said depression (3; 103) is curved and in that the center (C) of its mean radius of curvature (R) is located towards the rear part (102b; 202b; 302b; 402b) of said seat.

4. Seat according to claim 3, characterized in that said depression (3; 103) is a cavity with a curved edge, such as a bean-shaped cavity.

5. Seat according to claim 4, characterized in that said depression (3; 103) has a length of approximately

20 cm, a width of about 5 cm and a depth of at least about 8 mm.

6. Seat according to any one of claims 1 to 3, characterized in that said depression is created by a shoulder (10) formed in the thickness of said seat (102; 302).

7. Seat according to any one of the preceding claims, characterized in that said lumbar support (8, - 108; 208) is formed of a support structure whose external surface (8a), facing the user, has a concave profile in a horizontal plane and convex in a vertical plane.

8. Seat according to any one of the preceding claims, characterized in that it is fixedly mounted on a support, such as a substantially vertical partition or a base (14; 22).

9. Seat according to any one of claims 1 to 7, characterized in that said seat (202) is pivotally mounted between a position providing support to a normally seated user and a position providing support to a seated-standing user.

10. Seat according to claims 4 and 9, characterized in that it comprises two of said curved edge cavities (3; 103), which are respectively adapted to provide support to the ischia of the user in the seated position and in the seated position -standing.

11. Seat according to any one of the preceding claims, characterized in that said depression (3; 103) is filled with a deformable material having elastic properties, such as a foam, of lower density than said seat (2 ; 202; 302).

12. Seat according to any one of the preceding claims, of the type comprising a cover (15), including a portion (302) forming a seat cushion and a portion (106) forming a back cushion, fitted on a seat structure ( 17), characterized in that said depression (3) is formed in said portion forming a seat cushion and in that said lumbar support (208) is provided in said portion forming a back cushion (106).

13. Seat cover (15) comprising a seat portion (302) intended to cover the seat (20) with a seat structure (17) and a back portion (106) intended to cover the backrest (19) of a seat structure (17), characterized in that said seat portion (302) has at least one depression (3) adapted to serve as support for the ischions of a user and in that said back portion (106) provides lumbar support (208) to the user.

14. Cover according to claim 13, characterized in that it consists of a material whose density and / or 1 thickness are chosen from a range of values each of which corresponds to a range of given user weight.