BACKREST FOR A CHAIR AND CHAIR

Description

[0001] The present application relates to a backrest for a chair according to the preamble of claim 1. Furthermore, the present application relates to a chair according to the preamble of claim 12.

[0002] The backrest comprises a base by means of which the backrest can be connected or is connected to the rest of the chair. This connection can be achieved, in particular, by forming at least one pivot axis, so that the backrest can be pivoted about the pivot axis relative to a seat element that provides a seat for a person. A translational movement of the backrest relative to the rest of the chair is also possible, whereby the base, in particular, can be provided and configured to interact with the rest of the chair in a translationally movable manner. In particular, a translational movement in the horizontal direction ("forward and backward") can be enabled. The base can also be connected or is connected to a counterpart of the chair in a force-transmitting manner, so that forces acting on the backrest can be diverted into the rest of the chair and ultimately into a base.The base is not intended for a person to lean on. For example, the base may extend at an angle relative to a back element of the backrest, so that the backrest as a whole, viewed from the side, has a J-shaped configuration, with an at least substantially vertical section of the backrest being formed by the back element and the section extending at an angle relative to the backrest being formed by the base.

[0003] The backrest further comprises a back element that provides a support surface for the back of a person sitting on the chair. This allows the person to lean against the backrest, which supports the person's back.

[0004] The back element is connected to the base in a force-transmitting manner so that forces acting on the back element can be transferred to the base and then from the base into the rest of the chair and into the ground below. The back element comprises a plurality of individual support elements, each designed to support different areas of the back of the person sitting on the chair. For example, the support elements can interact with different areas of the back of each person, with the support elements each providing part of the backrest surface of the back element. It is conceivable that, depending on the person's sitting position, only some of the support elements or all of the support elements are used to transfer forces. This depends on how the person leans against the back element or its individual support elements.Therefore, it is conceivable, for example, that the person leans against the back element in such a way that only part of the backrest surface provided by some of the support elements comes into contact with the person's back, while other support elements are "inactive", i.e. do not come into contact with the person's back.

[0005] The chair to which the backrest is or can be connected can, in particular, be an office chair. The chair comprises a base frame for placement on a surface. It also comprises a seat element for providing a seat on which a person sitting on the chair can sit. The chair also comprises a backrest that provides support for the person sitting on the chair. For office chairs in particular, it is important that an ergonomic sitting position can be assumed, with office chairs typically providing a variety of adjustment options to enable them to be adapted to the individual stature of each person. This can, for example and in particular, relate to the adjustability of the backrest. State of the art

[0006] A backrest and a chair of the type described above are already known in the prior art. Reference is made, for example, to German Offenlegungsschrift DE 10 2018 123 731 A1. This document deals with a backrest and a chair, which can in particular be an office chair. The aim of this document is to provide a flexibly adjustable backrest. To this end, it is proposed to equip the backrest with a frame-shaped supporting structure connected to a backrest element. The latter comprises at least two different materials with different moduli of elasticity.

[0007] Furthermore, US 6,409,268 B1 discloses a backrest with a back element that provides a leaning surface. In an upper half of the back element, facing away from a base of the back element, a plurality of U-shaped slots are provided. This reduces the stiffness of the back element, allowing the backrest to deform more effectively and adapt to the shape of the person's back when a force is applied as a result of a person leaning against the backrest. Another backrest of this type is known from US 7,347,495 B2.

[0008] Furthermore, US Pat. No. 5,997,094 A discloses a chair with a two-part backrest. For this purpose, the backrest is slit in a U-shape, with the slit logically separating the two parts of the backrest. This allows the two parts of the backrest to deform independently of each other.

[0009] The design of backrests, especially those intended for office chairs, is extremely complex, as a multitude of requirements must be taken into account. This particularly applies to the support properties of the respective backrest, which should enable the person sitting on the chair to have optimal back support while still maintaining a high degree of freedom of movement, encouraging the person to remain "active" while sitting. In particular, it is highly recommended to regularly change one's sitting position throughout the day and thereby keep the body and muscles moving. The backrest of such a chair therefore actually has conflicting functions: stabilizing the back while simultaneously maintaining flexibility that allows the person to comfortably change their sitting position.Ideally, the backrest should be a component that is less noticeable to the person, so that support and load transfer occur as subconsciously as possible and the person is automatically encouraged to change their sitting position regularly. Task

[0010] The present application is therefore based on the object of providing a backrest and a chair equipped therewith that supports a healthy sitting behavior of a respective person. Solution

[0011] The underlying problem is solved according to the invention by means of a backrest having the features of claim 1. Advantageous embodiments emerge from the associated subclaims.

[0012] The backrest is characterized in that the support elements each have a web spaced from the base and two opposing flanges, each connected to one side of the associated web. A central axis of the web of a respective support element typically extends horizontally or in a horizontal plane when the backrest is viewed in a properly upright position, while central axes of the flanges each extend at least substantially vertically or in a vertical plane. The flanges of a respective support element face the base and are directly or indirectly connected to the base. The web of a respective support element is arranged at ends of the associated flanges spaced from the base. In this way, the support elements each form the shape of an inverted or upside-down U with respect to the base.

[0013] Preferably, the back element is formed with a plurality of U-shaped recesses, which may in particular be slot-shaped. These recesses divide the back element into the support elements, or the support elements are determined by the recesses in their shape. In other words, the back element can be formed such that the support elements are separated from one another by means of the recesses and are thus deformable at least substantially independently of one another.

[0014] Furthermore, it is provided that the support elements are arranged in a nested manner relative to one another in such a way that a support element located further outwards frames an adjacent support element located further inwards on three sides. In relation to a center of the backrest, which is enclosed on three sides by the support elements, the support elements are thus arranged in a nested manner, with a first, smallest, innermost support element being arranged starting from the center of the backrest and then adjoining it at least one further, larger, further outward support element framing the first support element. If more than two support elements are provided, a further, larger third support element is arranged further outwards and frames the second support element, which third support element is optionally framed in the same way by one or more further support elements.

[0015] Preferably, at least one support element, preferably at least the innermost support element, extends with its flanges into a lower end section of the back element. The "lower end section" refers to a section of the back element that, when the backrest is used as intended, either does not come into direct contact with the person's back at all or only comes into contact with a lower lumbar region. According to the invention, the backrest has a lumbar support, wherein the lower end section can be located, in particular, below the lumbar support.

[0016] The flanges preferably have a length measured along their respective central axis that is at least 50%, preferably at least 70%, more preferably at least 90%, of a length of the web associated with the flanges measured along a respective central axis. For example, the lengths of the flanges of a support element, in particular of the innermost support element, correspond at least substantially to the length of the web of the same support element.

[0017] The described embodiment of the backrest according to the invention has many advantages. In particular, the support elements each have different rigidities relative to the base, which is due to the different lengths of the flanges. This means that the first, innermost support element has the shortest flanges, i.e. the web of this first support element is arranged closest to the base compared to the other support element(s) further out. This has the consequence that this first support element is deflected to a lesser extent relative to the base under the action of an at least substantially horizontal force acting on its web than would be the case with a further outward support element.This is because a support element located further out generally has longer flanges, which means that the lever arm of a force acting on the web of the respective support element relative to the base is greater than for a support element located further in. The rigidity of the back element is therefore segmented by the nesting of the support elements, whereby the support elements are deformable at least essentially independently of one another. A deformation acting on one of the support elements therefore has no or only a very limited direct effect on the deformation of an adjacent or other remaining support element. The back element can therefore support a person's back as needed, where and in the manner that is individually required for the person in a particular sitting position.

[0018] In particular, the flanges of all support elements can extend into the lower end section of the back element.

[0019] At the same time, the support elements – as they are each individually suitable for transferring loads – allow the greatest possible flexibility when moving the person sitting on the chair. For example, an external support element can be subjected to a disproportionately high force when the backrest tilts sideways, while an internal support element, for example, hardly comes into contact with the person's back. Because the support elements act independently of one another, the support element subjected to the most severe load is deformed relatively strongly in the presence of the applied force and thus avoids the person's movement. Consequently, the person does not perceive the back element as an obstacle to free movement, but is instead encouraged to perform a movement without the back element exerting an unpleasantly harsh counterpressure on the back.

[0020] In an advantageous embodiment of the backrest according to the invention, the same comprises at least three, preferably exactly three, support elements. This number has proven particularly advantageous for providing individual support to a person's back in different areas as needed using the support elements. The use of three support elements compared to an alternative embodiment comprising more than three support elements is advantageous in that the flanges of the individual support elements can be dimensioned, while maintaining the usual dimensions of the back element, in such a way that they are mechanically suitable for dissipating forces that experience has shown to occur as a result of a person leaning against the support elements.

[0021] Furthermore, a design of the backrest can be advantageous in which at least two flanges of adjacent support elements, which are spatially associated with one another, are joined toward the base to form a common hyperflange. In other words, in such a design, the flanges of the adjacent support elements, each associated with the same side of the respective web, are "fused" into a common flange and thus do not extend to the base as separate flanges. The section in which the flanges are joined to form a common flange is referred to in the present application as the "hyperflange." Advantageously, the hyperflange is directly connected to the base.Nevertheless, it is also conceivable for the hyperflange, like the other flanges, not to be connected directly to the base, but rather, for example, to an intermediate section which then, for example, directly merges into the base. The intermediate section can be located in particular in a lower third, preferably a lower quarter, of the backrest. This means that the intermediate section is formed so low on the back element that, when the backrest is used as intended, it does not act as part of the backrest surface and, as such, is not directly subjected to forces from the back of a person leaning against it. The intermediate section can therefore be formed by the lower end section.

[0022] An advantageous embodiment is one in which the flanges of at least one of the support elements, preferably of several support elements, more preferably of all support elements, in sections in which they are present individually (i.e., in sections in which they do not form part of a hyperflange), have a length measured along their respective central axis that is at least 50%, preferably at least 70%, more preferably 90%, of a length of the respectively associated web measured along its central axis. The flanges and hyperflanges preferably extend into the lower end section of the back element.

[0023] If at least two flanges of adjacent support elements are combined to form a common hyperflange, it can also be advantageous if at least one further flange of a further support element is combined to form the hyperflange in the direction of the base. If at least three flanges are involved, the combination to form the hyperflange can take place at a common point or at different points, wherein in the latter variant, two flanges are first combined to form a hyperflange and then the third flange is added at a distance from the point at which this takes place, whereby a cross-section of the hyperflange is typically further enlarged. Preferably, a cross-section of the hyperflange corresponds at least substantially to a sum of the cross-sections of the flanges that are combined to form the hyperflange.

[0024] In one variant, the back element comprises a total of three support elements, wherein the flanges of the two outer support elements are joined from one point to form a common hyperflange, and the hyperflange extends to a lower end section of the back element. The flanges of the innermost support element also extend to the lower end section of the back element, wherein the flanges of the innermost support element are not part of the hyperflange, but extend individually over their entire length. Preferably, the lengths of the flanges of all support elements in which they are present individually are at least 50% of the length of the respective associated web.

[0025] In a further advantageous embodiment of the backrest according to the invention, the same comprises at least one stiffening strut, by means of which the flanges of at least one support element are coupled to one another in addition to the respective associated web. The stiffening strut is preferably connected to the ends of the flanges facing the base. In the sense of the present application, the stiffening strut is not as such part of the support elements, so that the latter have the U-shape described above. Preferably, at least one stiffening strut is designed such that it couples the flanges of several support elements to one another. It is also conceivable for the backrest to comprise a plurality of stiffening struts. Preferably, the at least one stiffening strut is oriented at least substantially parallel to the web of the respective associated support element.This effectively closes each support element at its open end facing away from the web, resulting in a self-contained supporting structure. The stiffening strut can be arranged, in particular, in the lower end section of the back element.

[0026] Furthermore, it can be particularly advantageous if the web of the innermost support element is arranged relative to the base such that a distance of said central axis from a lower end of the base, measured perpendicular to a central axis of the web of the support element, amounts to at least 50%, preferably at least 55%, more preferably at least 60%, of a total height which, in the sense of the present application, is measured from the lower end of the base to an upper end of the web of the outermost support element. In this embodiment, it is provided that the support elements - starting with the first, innermost support element - are functionally assigned to an upper part of the back of a respective person, in particular to an upper half of the back. In this area, the need for back support is typically greatest.

[0027] In a further advantageous embodiment, the web of at least one support element is doubly curved in the manner of a hyperbolic paraboloid. This preferably applies to the webs of all support elements of the backrest. The described shape has the advantage that the respective web, on its surface facing the back, which forms part of the backrest surface of the back element, has a shape adapted to the shape of the back, which is perceived as particularly comfortable. For this purpose, it is particularly advantageous if the web of the at least one support element is concavely curved along a central axis extending from flange to flange and convexly curved along a vertical axis oriented perpendicular to the central axis.

[0028] The back element can have a central, preferably flat, recess, which is framed on three sides by the support elements. The recess forms a free space that determines the shape of the innermost support element. Preferably, the innermost support element is defined by the recess toward the center of the back element and by a U-shaped recess toward the nearest, outermost support element. This is also implemented in the exemplary embodiment below.

[0029] The backrest according to the invention comprises a lumbar support arranged in a lower region of the backrest surface of the back element. This "lower region" is characterized by being framed by all support elements. Therefore, it is particularly advantageous if the lumbar support is formed centrally or centrally on the back element, so that the U-shaped support elements frame the lumbar support on three sides. In this embodiment, the support elements interact primarily with an upper region of a respective back, as explained above, while the lumbar support is intended and configured to support a lower region of the back, particularly in the region between the first and fifth lumbar vertebrae. The lumbar support is particularly well suited to correcting the sitting position of a person sitting on the associated chair and thereby preventing discomfort in the lumbar region.The lumbar support can in particular be inserted into a flat recess as described above, which is arranged in the lower area of ​​the back element.

[0030] According to the invention, the lumbar support is detachably mounted or mounted on the rest of the backrest, preferably on the base and / or a nearby support element, in a non-destructive manner. In this way, the lumbar support can be mounted or dismounted as needed, allowing, in particular, retrofitting of a lumbar support if necessary.

[0031] Furthermore, a lumbar support of this type is particularly advantageous if its position perpendicular to the backrest can be changed by means of an adjusting element, so that it can be adjusted as needed. Thus, depending on the shape of a particular person's back, the lumbar support can be brought into supportive engagement with the back when the person leans against the backrest. It is particularly advantageous if the lumbar support is adjustable in two directions, wherein preferably by adjusting in the first direction a support surface of the lumbar support can be adjusted back and forth at least substantially perpendicular to the backrest, and by adjusting in the second direction the support surface of the lumbar support can be adjusted up and down at least substantially parallel to the backrest. The directions in which the lumbar support can be adjusted are preferably oriented perpendicular to one another.

[0032] In a further advantageous embodiment of the backrest according to the invention, at least the back element is formed in one piece. Preferably, the backrest as a whole is formed in one piece, with the back element and the base being formed as a single part. In particular, the backrest can be manufactured using an injection molding process, thereby giving it a one-piece shape. This type of design is particularly advantageous because, in the absence of transitions from one component to another, associated weak points are avoided, which in practice can lead, for example, to noise due to relative movements of adjacent components.Furthermore, the one-piece design has the advantage that the individual elements of the backrest interact in a defined manner, whereas with assembled backrests, the quality of the connections between the components can influence the interaction. With the one-piece design, such sources of error are eliminated.

[0033] Particularly preferably, at least the back element, preferably the backrest as a whole, is formed from a glass-fiber-reinforced plastic. This can be, for example, polyamide with a glass fiber content of 30%. Such a design is particularly advantageous for keeping the overall mass of the backrest low, while the material exhibits high elasticity with a low tendency to fracture. This results in the backrest, in particular its back element, being particularly highly deformable without causing damage and / or plastic deformation.

[0034] In a further advantageous embodiment, the back element tapers towards the base. The base is preferably designed to be compact, so that it can be connected to the rest of the chair particularly easily. Accordingly, it is advantageous if the back element tapers towards an end facing the base, so that the back element, at its end facing the base, is at least substantially converged to the same size as the base.

[0035] In a further embodiment of the backrest according to the invention, the backrest comprises a backrest cover that is pulled over the back element in such a way that it encloses at least a portion of the support elements. It is conceivable that the backrest cover encloses all of the support elements of the back element or only a portion of the support elements.

[0036] The backrest cover can, in particular, be made of a knitted fabric. Furthermore, the backrest cover is preferably formed in one piece. For example, the backrest cover can be in the form of a sleeve that is open on one side, so that the backrest cover can be pulled over the backrest element particularly easily from an upper end of the backrest element facing away from the base.

[0037] The backrest cover can contribute to changing the visual appearance of the back element; moreover, the supporting effect the backrest cover can exert on the back of a person sitting on the associated chair can be technically important. For this purpose, it can be particularly advantageous if the back element has a cheek on each of its opposite lateral edges that protrudes perpendicular to the rest of the backrest surface, whereby the cheeks together give the back element a shell shape. In this embodiment, the backrest cover can be pulled over the back element, whereby the backrest cover is stretched between the lateral, opposing cheeks of the back element and is therefore suitable for absorbing forces acting perpendicular to a surface of the backrest cover.This allows the backrest cover to further enhance the supportive effect of the support elements and provide a more comfortable sitting experience for the person sitting on the chair. In particular, the protruding shape of the side panels ensures that the backrest cover, pulled over the side panels, first comes into contact with the back of a person leaning against the back element before the back comes into contact with one or more support elements, i.e., the actual backrest. This is particularly beneficial for seating comfort, as the moment the person leans back against the backrest, the back is initially "softly" cushioned by the backrest cover before the support elements are activated.

[0038] If the back element is designed in the manner described above with hyperflanges, which, for example, comprise the flanges of two outer support elements, it can be advantageous if the cheeks are formed in the region of the hyperflanges or if the hyperflanges are curved up at the lateral edges of the back element to form the aforementioned cheeks. In particular, the back element can comprise a total of three support elements, wherein the mutually associated flanges of the two outer support elements are each combined to form a hyperflange, and wherein the hyperflanges are curved up and form the cheeks. Preferably, the flanges of the innermost support element are not part of the hyperflange in this embodiment and extend individually.

[0039] The underlying problem is also solved according to the invention by means of a chair having the features of claim 12.

[0040] The chair is characterized in that its backrest is designed according to one of claims 1 to 11. The resulting advantages have already been explained above. In particular, the backrest supports the back of a person sitting on the chair without restricting their freedom of movement.

[0041] The chair can, for example, be an office chair, wherein the base is preferably equipped with casters so that the chair can be moved particularly easily on a surface. It can also be advantageous if the chair includes armrests on which the person sitting on the chair can rest their arms, for example their forearms. In accordance with general regulations for the design of office chairs, the chair can provide a variety of adjustment options in order to adapt it to the individual requirements of a particular person. In particular, it is conceivable for the backrest to be adjustable. For example, the backrest can be adjustable between a rigid and a swinging state. Furthermore, the chair can have a coupling between the seat element and the backrest, which causes the seat surface of the seat element to incline depending on the inclination of the backrest.Thus, for example, it is conceivable that the seat element will also be increasingly tilted backward as the backrest tilts backward. However, the inclination of the seat element is preferably significantly less than the inclination of the backrest. For example, one-third or one-quarter of the inclination of the backrest can be transferred to the seat element, so that the inclination of the latter—and thus of the seat surface—is tilted accordingly relative to the horizontal. Examples of implementation

[0042] The invention is explained in more detail below using an exemplary embodiment illustrated in the figures. It shows: Fig. 1: A view of a chair according to the invention from behind, Fig. 2: A view of the chair according to Figure 1from the side, Fig. 3: A view of a backrest according to the invention from the front, wherein the backrest is equipped with a lumbar support, Fig. 4: A perspective view of the backrest according to Figure 3 , but without lumbar support, Fig. 5: A view of the backrest according to Figure 4 from the front, Fig. 6: A view of the backrest according to Figure 4 from the side, Fig. 7: A perspective view of the backrest according to Figure 4 from behind.

[0043] An example of implementation that is shown in the Figures 1 to 7 shown includes a chair 2, which is formed here by an office chair. The chair 2 includes a seating element 18, which has a seating area 19 for one on the chair 2 seated person. Furthermore, the chair includes 2 two opposite each other, on the side of the seat element 18 arranged armrests 23, which are particularly well suited to the Figures 1 and 2 Furthermore, the chair includes 2 a base frame 22, In the example shown, a total of five diagonally spread legs, each with a castor 30 By means of the base frame 22 is the chair 2 The remaining elements of the chair 2 are formed by a vertical axis of rotation 24 with the base frame 22 connected, so that a rotating function is provided. Therefore, the chair shown is 2 a swivel chair.

[0044] The chair also includes 2 a backrest according to the invention 1, which has a back element 4 and a base 3 By means of the basis 3 is the backrest 1 to the remaining chair 2 connected, as can be seen particularly well from Figure 2The connection of the backrest 1 to the remaining chair 2 is realized here in such a way that the backrest 1 overall around a transversely oriented pivot axis 31 relative to the chassis 22 can be swiveled. In the Figures 1 and 2 is the backrest 1 each shown in a non-tilted state.

[0045] The back element 4 In the example shown, it comprises a total of three support elements 6, 7, 8 which are particularly well suited to the Figures 3 to 7 By means of the support elements 6, 7, 8 forms the back element 4 a leaning surface 5 from one on the chair 2 seated person to lean with their back against the backrest 1 is available. In the Figures 1 and 2 In the embodiment shown, the backrest comprises 1in addition to the support elements 6, 7, 8 a lumbar support 15, by means of which the back of a person can be supported in the lumbar region. The lumbar support 15 is in a middle 11 the backrest 5 arranged, whereby in the example shown the lumbar support 15 into a central recess 28 which is surrounded by the support elements on three sides 6, 7, 8 This is described below in connection with the supporting elements 6, 7, 8 explained separately.

[0046] The lumbar support 15 includes an adjusting element 25, by means of which a position of a support surface of the lumbar support 15 relative to the support elements 6, 7, 8 adjustable so that the lumbar support 15 can be adjusted to the individual needs of each person. The lumbar support 15adjustable in two separate directions, which in the example shown are oriented perpendicular to each other. By adjusting the first direction, the support surface of the lumbar support can be 15 in a position at least substantially perpendicular to the backrest 5 oriented direction forwards and backwards and by means of an adjustment in the second direction at least substantially parallel to the backrest 5 oriented direction up and down. To attach the lumbar support 15 is the same by means of fastening means 35 on the back element 4 This is particularly evident in the Figure 3 .

[0047] The support elements already mentioned 6, 7, 8 each include a bridge 9 and two flanges each 10. The flanges 10 are located at opposite ends of the respective web 9connected so that the support elements 6, 7, 8 each have a U-shape. Since the webs 9 each at the base 3 opposite ends of the flanges 10 are arranged, the U-shape of each support element 6, 7, 9 "turned over." The support elements 6, 7, 8 are arranged in such a way that a support element located further outwards 7, 8 a support element located further inside 6, 7 framed on three sides. This is particularly evident in the Figures 3 and 5 .

[0048] The support elements 6, 7, 8 together form the leaning surface 5 that is available for a person to lean on. The support elements 6, 7, 8 in the example shown relative to the base 3 arranged so that a distance 33 between a lower end 34 the base 3and a central axis 13 of the bridge 9 of the innermost support element 6 here about 65% of a total height 32 which differs from the lower end 34 the base 3 up to an upper end 29 of the back element 4 This is particularly evident in the Figure 3 . The described arrangement results in a gap between the base 3 and the bridge 9 of the innermost support element 6 there is a comparatively large free space in which the recess 28 which in turn contains the lumbar support 15 can be used or is used. The design of the support elements 6, 7, 8 in the manner described leads to the fact that the 9 provided sections of the leaning area 5 suitable for supporting the upper back area. The lumbar support15, which, in terms of height, refers to the base 3 below the webs 9 of the support elements 6, 7, 8 is particularly well suited for supporting the lower back area, especially the lumbar region.

[0049] The nested arrangement of the support elements 6, 7, 8, in which a further outer support element 7, 8 a further inner support element 6, 7 framed on three sides, leads to the supporting elements 6, 7, 8 have different stiffnesses. This is due to the length of the respective flanges 10 and the resulting lever arms that the webs 9 the supporting elements 6, 7, 8 relative to the base 3 Therefore, the outermost support element 8 the lowest stiffness of the three support elements 6, 7, 8 which leads to the support element 8when a force is applied to its web 9, which is at least substantially perpendicular to the backrest 5 oriented, stronger relative to the base 3 deflected than would be the case with a similar load on the web 9 of the innermost support element 6 would be the case. The support elements 6, 7, 8 behave accordingly when subjected to a load resulting from the leaning of a back against the back element 4 different in that a further outer support element 7, 8 deforms more under the same load than a support element located further inside 6, 7. This is particularly advantageous for seating comfort, as typically with a greater distance from the base 3 a larger deformation in the area of ​​the backrest 5This is intended to partially offset the leaning back and thus avoid creating a "hard" impact against the back. This preserves the person's freedom of movement, as the back is not restricted in its freedom of movement.

[0050] For the described segmentation of the backrest 5 are the flanges 10 important, since these are each separately assigned to the corresponding webs 9 of the respective support element 6, 7, 8 are assigned. The support elements 6, 7, 8 or in particular their webs 9 are essentially deformable independently of each other, so that a load on one of the webs 9 does not directly lead to a deformation of another web 9 The back element 4 In this way, the back of each person can be individually supported in different areas.

[0051] The footbridges 9 of the back element4 are each shaped like a hyperbolic paraboloid, as can be seen particularly well in Figure 6 Therefore, the bridges 9 each with a double curve. In the example shown, this double curve is designed in such a way that - when viewed from the front side of the back element 4 viewed - the bridges 9 each along its central axis 13, which extends from flange 10 to flange 10 of the respective support element 6, 7, 8 extends, concave and along its perpendicular to the central axis 13 oriented vertical axis 14 are convexly curved. This design is responsible for the seating comfort that the back element 4 offers, particularly advantageous.

[0052] In the example shown, flanges assigned to each other 10 the two outer support elements 7, 8 in one area on the basis 3to a hyper flange 12 Therefore, a recess that connects the flanges 10 the supporting elements 7, 8 in their upper areas, in the area of ​​the hyperflange 12 not present, so that the latter, so to speak, both flanges 10 contains.

[0053] Furthermore, in the example shown, the opposing hyperflanges 12 and the flanges 10 of the innermost support element 6 at the base 3 facing ends 21 the flanges 10 by means of a stiffening strut 20 connected to each other. Starting from the stiffening strut 20 are the supporting elements 6, 7, 8 indirectly by means of an intermediate section with the base 3 connected, wherein the intermediate section is so deep on the back element 4is designed so that when the backrest is used as intended 1 not as part of the leaning area 5 and as such is not directly subjected to forces or contact with the back of a person leaning against it. Therefore, the flanges extend 10 to a lower end section of the back element 4. In the example shown, this is done in such a way that the flanges 10 of the innermost support element 6 individually (that is, not as part of a hyperflange 12 ) to the lower end section of the back element 4 and the flanges of the other two support elements 7, 8 above the lower end section to hyper flanges 12 are brought together and are part of the hyperflange 12 extend to the lower end section.

[0054] The individual flanges 10of the innermost support element 6 have a length measured along their central axis which is approximately the same as the length of the corresponding web measured along its central axis 9 The individual flanges 10 of the middle support element 7 have a length measured along their central axis which is approximately 50% of the length of the corresponding web measured along its central axis 9 The individual flanges 10 of the outermost support element 8 have a length measured along their central axis which is approximately 70% of the length of the corresponding web measured along its central axis 9 corresponds.

[0055] The backrest 1 In the example shown, it is formed as a single piece, being manufactured by means of an injection molding process. In this way, the support elements 6, 7, 8,the intermediate section and the base 3 directly into one another. The backrest 1 is made of a glass-fiber reinforced plastic.

[0056] The support elements 6, 7, 8 are defined by recesses that are cut into the back element 4 The innermost support element is 6 to the middle 11 the backrest 5 through the central recess 28 and to the middle support element 7 limited or defined by a U-shaped recess. The U-shaped recess is slot-shaped. The middle support element 7 is also defined by a U-shaped recess towards the outermost support element 8, which is also slot-shaped here. The outermost support element 8 forms an outer edge of the back element 4.

[0057] In a particularly advantageous design, the backrest has 1 via a backrest cover 16, which is exemplified here using the Figures 1 and 2 The backrest cover 16 is made of a seamless knitted fabric. 16 This is a case open to one side, which is formed by the upper end 29 of the back element 4 here over it. In the example shown, this is done in such a way that the two outer support elements 7, 8 from the backrest cover 16 are wrapped, while the innermost support element 6 outside the backrest cover 16 remains.

[0058] The backrest cover 16 On the one hand, this leads to an appearance of the back element 4 is standardized, since the segmented design of the back element 4,which are due to the individual support elements 6, 7, 8 visually creates a coherent leaning surface 5 Apart from that, the backrest cover 16 In the example shown, it also has a technical function. This is due to the fact that the back element 4 in the area of ​​hyper flanges 12 with over the remaining backrest 5 protruding cheeks 36 is designed or the hyper flanges 12 to form the cheeks mentioned 36 on the side edges of the back element 4 This is particularly evident in the Figures 4 and 6 . As a result of this design, the back element 4 a shell shape, as is known from typical bucket seats. This in turn leads to the backrest cover 16 when arranged on the back element 4 over the cheeks36 This ensures that the backrest cover 16 suitable for absorbing forces acting perpendicular to its surface, producing an elastic deformation and thus supporting the back of a person leaning against it. Since the cheeks 36 a little way over the remaining leaning area 5 protrude, the back of the person leaning on the backrest first comes into contact with the backrest cover 16, before finally the support elements 6, 7, 8 be activated.

[0059] For attaching the backrest cover 16 on the back element 4 includes the back element 4 in the example shown two grooves 26, 27, which are suitable for use with correspondingly designed piping of the backrest cover 16 to work together in a form-fitting manner and thereby create a force-transmitting connection of the backrest cover 16 with the back element 4 to produce. List of reference symbols

[0060] 1Backrest 2Chair 3Base 4Back element 5Backrest 6Support element 7Support element 8Support element 9Bar 10Flange 11Center 12Hyperflange 13Center axis 14Vertical axis 15Lumbar support 16Backrest cover 17Foot frame 18Seat element 19Seat 20Bracing strut 21End 22Foot frame 23Armrest 24Pivot axis 25Adjusting element 26Groove 27Groove 28Recess 29End 30Castle 31Pivot axis 32Total height 33Distance 34End 35Fasteners 36Chinch

Claims

1. A backrest (1) for a chair (2), in particular an office chair, comprising - a base (3), by means of which the backrest (1) can be or is connected to the chair (2), - a backrest element (4) for providing a reclining surface (5) for the back of a person sitting on the chair (2), wherein the backrest element (4) is connected in a force-transmitting manner with the base (3), wherein the backrest element (4) comprises a plurality of support elements (6, 7, 8), wherein the support elements (6, 7, 8) are set up to each support different areas of the back, wherein the support elements (6, 7, 8) each have a web (9) spaced apart from the base (3) as well as two opposing flanges (10) each connected to one side of the accompanying web (9), wherein the flanges (10) of a respective support element (6, 7, 8) each face the base (3) and are indirectly or directly connected with the base (3), wherein the web (9) of a respective support element (6, 7, 8) is arranged on ends of the accompanying flange (10) spaced apart from the base (3), so that the support elements (6, 7, 8) are each invertedly U-shaped in relation to the base (3), wherein the support elements (6, 7, 8) are nested relative to each other in such a way that-in relation to a center (11) of the reclining surface (5)-a respective more outwardly lying support element (7, 8) frames a more inwardly lying adjacent support element (6, 7) on three sides, wherein a stiffness of the backrest element (4) is segmented via the nesting of support elements (6, 7, 8), and the support elements (6, 7, 8) can be formed at least essentially independently of each other, wherein the support elements (6, 7, 8) each have different stiffnesses in relation to the base due to differing lengths of the flanges (10), so that the support elements (6, 7, 8) behave differently when exposed to a load from a back leaning against the backrest element (4), such that a more outwardly lying support element (7, 8) deforms more strongly than a more inwardly lying support element (6, 7) under an identical load, wherein a lumbar support (15) is provided, which is arranged in a lower area of the backrest element (4), which is framed by all support elements (6, 7, 8), characterized in that the lumbar support (15) can be or is non-destructively, detachably mounted to the remaining backrest (1).

2. The backrest (1) according to claim 1, characterized in that the backrest element (4) comprises at least three, preferably precisely three, support elements (6, 7, 8).

3. The backrest (1) according to one of the preceding claims, characterized in that at least two flanges (10) of adjacent support elements (7, 8) are merged into a common hyper-flange (12) in the direction toward the base (3), wherein the hyper-flange (12) is preferably connected directly to the base (3).

4. The backrest (1) according to claim 3, characterized in that at least one additional flange (10) of a support element (6) is merged with the hyper-flange (12) in the direction toward the base (3).

5. The backrest (1) according to one of the preceding claims, characterized in that the flanges (10) of a first, more inwardly lying support element (6, 7) are shorter than the flanges (10) of a second support element (7, 8) lying more outwardly relative to the first support element (6, 7).

6. The backrest (1) according to one of the preceding claims, characterized in that the web (9) of at least one support element (6, 7, 8), preferably the webs (9) of all support elements (6, 7, 8) are doubly curved in design to resemble a hyperbolic paraboloid, wherein the web (9)-as viewed on a front side of the backrest element (4)-is preferably concavely curved along a central axis (13) extending from flange (10) to flange (10), and convexly curved along a vertical axis (14) oriented perpendicular to the central axis (13).

7. The backrest (1) according to one of the preceding claims, characterized in that at least the backrest element (4), preferably the backrest (1) as a whole, is designed as a single piece.

8. The backrest (1) according to claim 7, characterized in that at least the backrest element (4), preferably the backrest (1) as a whole, is made out of a glass fiber-reinforced plastic.

9. The backrest (1) according to one of the preceding claims, characterized in that the backrest element (4) tapers toward the base.

10. The backrest (1) according to one of the preceding claims, characterized by a backrest cover (16), which is pulled over the backrest element (4) in such a way as to cover at least a portion of the support elements (6, 7, 8), preferably all support elements (6, 7, 8).

11. The backrest (1) according to claim 10, characterized in that the backrest cover (16) is made out of a stretchy knitted fabric.

12. A chair (2), in particular an office chair, comprising - a pedestal (17) for setting up the chair (2) on a surface, - a seat element (18) for providing a seat surface (19), - a backrest (1) for providing a reclining surface (5) for the back of a person sitting on the chair (2), characterized in that the backrest (1) is designed according to one of claims 1 to 11.