WO2021214208A1

WO2021214208A1 - Chair

Info

Publication number: WO2021214208A1
Application number: PCT/EP2021/060516
Authority: WO
Inventors: Eugen LETOW; Björn OSTERKAMP; Boris REDWANZ; Tobias Schmitz; Carlo Shayeb
Original assignee: Vitra Patente Ag
Priority date: 2020-04-22
Filing date: 2021-04-22
Publication date: 2021-10-28
Also published as: EP4138612A1; US20230232990A1; CH717338A1

Abstract

The invention is directed to a chair (1) having a seat (4), a backrest carrier (2) and a backrest (3), wherein the backrest carrier (2) is mounted on the seat (4) and the backrest (3) is mounted on the backrest carrier (2), and the chair (1) is designed so that, when the chair is in a sitting position, a user can sit on the seat and rest his back against the backrest (3). The chair (1) also has a lean-on part (5), which differs from the backrest (3), wherein the backrest (3) is connected in a tiltable manner to the backrest carrier (2), and it can therefore be swung in the direction of the seat (4), from the sitting position into a supporting position, and wherein the lean-on part (5) is coupled to the backrest (3) such that, as it is being swung from the sitting position into the supporting position, the backrest (3) orients the lean-on part (5) such that the user can support his buttocks on the lean-on part (5).

Description

DESCRIPTION

title

CHAIR

Technical area

The invention relates to a chair according to the preamble of independent claim 1.

Such chairs with a sitting and a support position can be used to change the working position of a user, that is, for example, from a sitting to a standing leaning or supported position to help avoid postural damage and / or any back problems, which experience has shown can occur in purely sedentary activities over a long period of time.

State of the art

From DE 10 2015 119 937 B3 a chair is known which comprises a seat surface and a backrest-like abutment element connected via lateral support elements to the seat surface and pivotable about a pivot axis, which in a first pivot position as a backrest for one on the seat surface seated user and is designed to be used in a second pivot position as a support surface for a user who is supported on the support surface while standing. The pivot axis of the abutment element is arranged at the upper end of the carrier elements above the seat surface. In this chair, the abutment element - i.e. the backrest / backrest - is exposed to relatively heavy loads, especially in the second swivel position. In addition, the side support elements and the pivot axis above the seat limit the design freedom of the chair significantly.

The present invention is based on the object of proposing a chair which can be used both for sitting and for leaning against or supported Can be used standing and which is designed in such a way that the individual components, especially in the standing leaning or supported position, are not exposed to excessive loads.

Presentation of the invention

The object is achieved according to the invention by a chair as defined in independent claim 1. Advantageous variant embodiments of the invention emerge from the dependent claims.

The essence of the invention consists in the following: A chair comprises a seat, a backrest support and a backrest: the backrest support is mounted on the seat and the backrest on the backrest support. The chair is designed so that in a sitting position a user can sit on the seat and lean his back against the backrest. The chair furthermore comprises a backrest part that is different from the backrest, the backrest being tiltably connected to the backrest support so that it can be folded from the sitting position into a support position in the direction of the seat. The backrest part is coupled to the backrest in such a way that the backrest aligns the backrest part when it is folded from the sitting position into the support position so that the user can support his buttocks on the backrest part.

The chair can be, for example, an office chair. In principle, however, all types of chairs can have such a design, such as living room, kitchen or garden chairs.

In connection with the present chair, the term “seat” refers to an entire seat structure. In the case of office chairs in particular, such seat constructions typically include a seat support and a mostly upholstered or elastic seat pad. The seat carrier can support and carry the seat pad in such a way that a user of the chair can sit on the seat structure by positioning his buttocks on the seat pad or by putting on or off the seat pad.

The backrest support can be fixed or attached to the seat or it can be movable to the seat. In particular, it can be tilted backwards to a predetermined or variably adjustable extent for the seat. The seat can also have a synchronous mechanism with which the seat support and the backrest or the backrest support can be tilted or inclined at the same time as the seat support in a predefined manner or in a predefined relationship.

The backrest can be connected to the backrest support so that it is adjustable in height. For this purpose, the backrest or the seat support can be equipped with a longitudinally adjustable element.

In the sitting position, the backrest is oriented so that a user can lean his back on it when he is sitting on the seat. This can be a preferred position for sedentary work.

The term "foldable in the direction of the seat" in connection with the backrest refers to the fact that the backrest can be tilted towards a surface of the seat. Typically, the chair describes a rear side, on which the backrest is located, and a front side, on which the legs of the user are when he is sitting on the seat in the sitting position. The backrest can be folded in the direction of the seat by folding it forward or in the direction of the front of the chair. The chair can also have a central axis which typically runs vertically, quasi-centrally through the seat. The backrest can be folded in the direction of the seat by being able to fold it towards the central axis.

Because the backrest is provided as a different or separate component from the backrest, optimal load transfer - especially in the support position of the chair according to the invention - can be guaranteed and the load on the corresponding components minimized. The chair according to the invention can thus efficiently make it possible that it is not exposed to excessive stress, particularly in the support position in which the user can lean on or support while standing.

In addition, the backrest part in the inventive embodiment enables the weight of the user leaning against the chair in the support position to be pressed comparatively centrally, so that the risk of the chair being pushed away by the user leaning against it can be reduced. [0015] Furthermore, a stable and efficient construction with comparatively few, simple components can be achieved with the opposing backrest part which can be folded out according to the invention.

The chair according to the invention can thus be used efficiently and safely both for sitting and for leaning or supported standing. This can be desired, for example, when the working position at a height-adjustable work desk or desk changes. In particular, the chair can enable comfortable working in two positions in addition to a standing position, namely a classic sitting position and a half-sitting position in which the user leans against the chair half-standing, half-sitting.

Preferably, the backrest is tiltably connected to the backrest support in that it is pivotably mounted on the backrest support so as to be rotatable about a first or lower axis. This creates a prerequisite for a particularly effective adjustability of the individual components with respect to one another.

Preferably, the backrest part is coupled to the backrest in that it is pivotably mounted on the backrest, rotatable about a second or upper axis. Preferably, the backrest part is at the same time rotatable, articulated or else bendable about a third or central axis mounted on a backrest part carrier. The third or middle axis is stationary, the second or upper axis being moved along with the backrest when tilted. In this way, the positioning of the backrest part can be achieved in a particularly simple and efficient manner.

Preferably, the first axis is arranged below the second axis. By means of this measure, particularly suitable positions for standing, leaning or supported work can be set.

The backrest part is preferably coupled to the backrest in such a way that the second axis can be displaced along the backrest. In this way, the variability of the setting can be increased. In addition, a comparatively large leaning surface can be provided in the support position.

[0021] The chair preferably comprises a counter-backrest part carrier, the counter-backrest part carrier being designed to be essentially stationary with respect to the backrest carrier. Of the The term “essentially stationary with respect to the backrest support” in connection with the backrest part support can refer to the fact that the backrest support and the backrest part support are immovable with respect to one another and, in particular, cannot be tilted. Due to the elasticity of their material, the two carriers can be easily bent with respect to one another, but the two carriers are relatively solid and are not intended to be bent or moved with respect to one another. The backrest part support can for example be attached to the seat or to the backrest support. The backrest support and the backrest support can also be designed in one piece. With the backrest part carrier, a stable mounting of the backrest part can be guaranteed in each case.

Preferably, the backrest part is mounted on the backrest part support so that it extends between the backrest part support and the backrest. In this way, the weight force possibly acting on the backrest part can be absorbed in a particularly efficient manner.

Preferably, the backrest part is tiltably mounted on the backrest support so that it can be moved from a quasi upright position to an inclined position when the backrest folds from the sitting position into the supporting position. Here, an inclination of the backrest part between 0 ° and 60 °, preferably between 5 ° and 45 ° relative to a horizontal, has proven to be particularly suitable for a standing, leaning or supported position.

Preferably, the backrest part is designed to be bendable, so that it is curved from a quasi upright position into an inclined position when the backrest folds from the sitting position into the supporting position. By means of this variant, the assembly effort can be reduced and an appropriate leaning in the support position can be achieved.

Preferably, the backrest part is elastic at least in sections, so that it can be bent. Such a configuration has proven to be favorable with regard to efficient production.

Preferably, the backrest part is at least partially designed like a roller shutter, so that it can be bent. The term “roller shutter-like” in this context refers to an arrangement that has several horizontal segments or Has struts, of which in any case a plurality are articulated to one another in order to be able to carry out a curvature at least in sections. In this way, a particularly robust design of the backrest part can be achieved.

Preferably, the backrest part is slidably mounted on the backrest part support so that it is moved to the backrest part support when the backrest folds from the sitting position into the support position. In this way, the total length of the backrest part carrier and the backrest part can be changed. In particular, the backrest part can be displaceable quasi vertically to the backrest part carrier. In this way, the variability of the chair can be further increased.

The backrest part carrier is preferably equipped with a guide in which the backrest part is held displaceably. This can enable a reliable and efficient implementation of the support position. The backrest part is preferably received in the guide in a sandwich-like manner. This is particularly preferred if the counter-back element is designed like a roller shutter at least in sections, so that it can be bent. In this case, in turn, a plurality of horizontal segments or struts are preferably provided, a plurality of which are in any case articulated with one another in order to be able to carry out a curvature at least in sections. The backrest part can then, so to speak, be pulled out of the guide or pushed back into the guide.

The backrest part is preferably arranged within the guide in such a way that its lower end forms a stop when the support position is reached, i.e. when the backrest element has been completely pulled out of the guide. For example, the stop can be formed via a screw connection which is slidably received in corresponding grooves in the guide.

Preferably, the backrest part is displaceably guided on a support piece, wherein the support piece is arranged rotatably about an axis A3 on the backrest part carrier. The axis A3 here represents the second support point of the backrest part. This configuration has proven to be particularly efficient and robust. In particular, by means of the support piece, the backrest part can be mounted so displaceably on the backrest support that, during operation, a movement between the backrest part and the backrest part support can be compensated for, especially in the direction of the seat. Preferably, the chair has an underframe on which the seat is mounted, the underframe being equipped with castors for placing on a floor, which are designed to be braked. The term “braked” in this context refers to the fact that the rollers cannot rotate freely but are prevented from rotating freely to a certain extent. In this way, the castors can prevent the chair from rolling away when the user leans against the backrest. In this respect, these rollers can also be supported or supplemented by a stopper element which is formed on the floor side on the underframe or base.

Preferably, the chair has a sitting direction in which the user can sit down on the seat, and a support direction in which the user can support his buttocks on the backrest part, the seat direction and the support direction being virtually opposite. This creates a prerequisite for the most even possible loading of all components. In addition, the center of gravity can be kept in the area of the vertical axis (or the central axis) of the chair.

Brief description of the drawings

Further advantageous embodiments of the invention emerge from the following description of exemplary embodiments of the invention with the aid of the schematic drawing. In particular, the chair according to the invention is described in more detail below with reference to the accompanying drawings using exemplary embodiments. Show it:

1a: a chair according to a first embodiment of the invention with an upright backrest in the sitting position;

1b: the chair according to FIG. 1a with the backrest tilted forward in the support position;

2a: a chair according to a second embodiment of the invention with an upright backrest in the sitting position;

FIG. 2b: the chair according to FIG. 2a with the backrest tilted forward in the support position; 3a: a chair according to a third embodiment of the invention with an upright backrest in the sitting position;

3b: the chair according to FIG. 3a with the backrest tilted forward in the support position;

4a: a chair according to a fourth embodiment of the invention with an upright backrest in the sitting position;

4b: the chair according to FIG. 4a with the backrest tilted forward in the support position;

5a: a chair according to a fifth embodiment of the invention with an upright backrest in the sitting position;

FIG. 5b: the chair according to FIG. 5a with the backrest tilted forward in the support position;

6a shows a chair according to a sixth embodiment of the invention with an upright backrest in the sitting position; and

6b shows the chair according to FIG. 6a with the backrest tilted forward in the support position.

Weo (e) for carrying out the invention

Certain terms are used in the following description for practical reasons and are not to be understood as limiting. The words “right”, “left”, “down” and “up” indicate directions in the drawing to which reference is made. The terms “inward”, “outward”, “below”, “above”, “left”, “right” or similar are used to describe the arrangement of designated parts with respect to one another, the movement of designated parts with respect to one another and the directions towards or away from Geometric center of the invention and named parts of the same as shown in the figures used. These relative spatial information also include positions and orientations other than those shown in the figures. For example, when a part shown in the figures is turned over, elements or features that are described as “below” are then “above”. The terminology includes the words expressly mentioned above, derivatives from them, and words with similar meanings.

In order to avoid repetition in the figures and the associated description of the various aspects and exemplary embodiments, certain Features are to be understood as common for different aspects and exemplary embodiments. The omission of an aspect in the description or a figure does not imply that this aspect is missing in the associated exemplary embodiment. Rather, such an omission can serve the purpose of clarity and to prevent repetition. In this context, the following definition applies to the entire further description: If reference characters are contained in a figure for the purpose of graphic clarity, but not mentioned in the directly associated description text, reference is made to their explanation in the preceding figure descriptions. If, in addition, reference symbols are mentioned in the descriptive text that belongs directly to a figure and are not contained in the associated figure, reference is made to the preceding and following figures. Similar reference numbers in two or more figures stand for similar or identical elements.

A first embodiment of the present invention is illustrated in FIGS. 1a and 1b. This initially comprises generally (i.e. like the other embodiments as well) a chair 1 with a seat 4, a backrest support 2 and a backrest 3, the backrest support 2 being mounted on the seat 4 and the backrest 3 on the backrest support 2. The chair 1 is designed so that in a sitting position (cf. FIG. 1 a) a user can sit on the seat 4 and lean his back against the backrest 3. The chair 1 comprises a backrest part 5 different from the backrest 3, the backrest 3 being tiltably connected to the backrest support 2 so that it can be folded from the seated position into a support position in the direction of the seat 4 or a central axis X. The backrest part 5 is coupled to the backrest 3 in such a way that the backrest 3 aligns the backrest part 5 when folding from the sitting position (see. Fig. 1a) into the support position (see Counter-backing part 5 can support.

When folding or tilting the backrest 3 from the sitting position according to FIG. 1a into the supporting position according to FIG. 1b, the backrest 3 is tilted or rotated about a first, lower axis Ai on the backrest support 2. The first, lower axis Ai is fixedly or displaceably arranged on the backrest support 2 and is preferably located above the seat 4. The backrest 3 takes along the counter-backrest part 5, which is coupled to it via a second, upper axis A2, so that it is aligned for the support position or can be inclined. The second, upper axis A2 becomes accordingly Moved with the backrest 3 in the direction of the central axis X, at the same time the upper end of the backrest part 5 rotates to align the same about the axis A ₂ and is moved with it. The second, upper axis A ₂ and thus also the counter-back part 5 cannot be displaced with respect to the backrest 3 in this embodiment. The second, upper axis A ₂ can be arranged in the backrest 3 or behind the backrest 3.

The lower end of the backrest part 5 is rotatably and fixedly or displaceably arranged on a backrest part support 6 _{via a third, central axis A 3 (see double arrow in FIG. 1b).} The backrest part support 6 can be part of the backrest support 2 (ie one on the left or right side of the backrest 3) or it can be connected as a separate part to the seat 4 and extend with a substantially vertical section between the two backrest supports 2 . The backrest 3 can have a convex bend, in particular in the lower half, in order to facilitate functionality or to enable ergonomic sitting.

Basically, the center of gravity should preferably be in the area of or as close as possible to the central axis X, even when used in the support position. In this way, the weight of a user leaning back in the support position can act comparatively centrally on the chair and the chair 1 can be prevented from rolling away or shifting.

The seat 4 is mounted on a seat post 9 through which the central axis X extends. At the lower end of the perch 9, the underframe or the base 7 is arranged, which has castors 8. The castors 8 are preferably designed to be braked, i.e. in any case they partially block against the chair 1 from rolling away to the side if, for example, the user is leaning against the backrest part 5 in the support position. The perch 9 is mounted in a hydraulic cylinder 10, via which it can be adjusted vertically up and down. A seat height of the chair 1 can thus be adjusted. In addition, the seat post 9 is rotatably held in the hydraulic cylinder 10 so that the seat 4 can be rotated about the central axis X.

Further embodiments of the chair 1 according to the invention shown in the figures are described below. In many aspects, these embodiments are designed analogously to the embodiment of FIGS. 1a and 1b. These common aspects are not all detailed again below, but reference is made to the above description of the exemplary embodiment of FIGS. 1a and 1b.

2a and 2b, a second embodiment of the present invention is shown. Here the upper end of the backrest part 5 is designed to be movable with respect to the backrest 3 of the chair 1. When tilting the backrest 3 from the seated position (see Fig. 2a) to the support position (see Fig. 2b) about the first, lower axis Ai, the upper end of the backrest part 5 together with the second, upper axis A ₂ in a corresponding guide 11 slid downward. In this way, the variability of the chair 1 can be further increased and the center of gravity can be shifted somewhat further in the direction of the central axis.

When the backrest 3 is straightened up again, the backrest part 5 is _{moved upwards again together with the second, upper axis A 2} in the guide 11, as indicated by the double arrow in FIG. 2b. The first, below axis Ai, is again preferably arranged above the seat 4. The guide 11 is preferably designed so that the backrest part 5 can be aligned maximally horizontally. In other words, the second, upper axis A ₂ should preferably be at the maximum level with the third, central axis A ₃ , but not below it (this applies in principle to all embodiments).

A third embodiment of the present invention is illustrated in Figures 3a and 3b. Here, when the backrest 3 is tilted from the seat (see Fig. 3a) to the support position (see Fig. 3b), the at least partially elastic counter-back part 5 is _{curved around the third, central axis A 3} , with the desired inclination of the Counter-leaning part 5 adjusts. The backrest part 5 can in principle be formed from any elastically deformable material.

The upper end of the backrest part 5 is movably coupled to the backrest 3 _{via the second, upper axis A 2.} The lower end of the backrest part 5 is fixedly connected to the backrest part carrier 6 and can thus be bent about the third, central axis A ₃ when the backrest 3 is tilted. The backrest 3 is in turn tiltably connected to the backrest support 2 by being mounted on the backrest support 2 so as to be rotatable about the first, lower axis Ai. Another preferred embodiment of the present invention is indicated in FIG. 3b. This comprises a guide 12 (shown in dashed lines) which is arranged at the upper end of the backrest part carrier 6 and in which the backrest part 5 is received in a sandwich-like manner. This particular design is used in particular when the counter-back element 5 is designed like a roller shutter, at least in sections, so that it can be bent. In this case, a plurality of horizontal segments or struts are preferably provided, a plurality of which are connected to one another in an articulated manner in order to be able to carry out a curvature at least in sections. The backrest part 5 can then, so to speak, be pulled out of the guide 12 or pushed back into the guide 12, as indicated by the dashed double arrow.

The backrest part 5 is preferably arranged within the guide 12 that its lower end forms a stop when the support position is reached (eg via a screw connection which is slidably received in corresponding grooves of the guide), ie when the backrest element 5 was pulled out of the guide 12.

A fourth embodiment of the present invention is illustrated in FIGS. 4a and 4b. Here, the first, lower axis A-i, via which the backrest is articulated and rotatably coupled to the backrest support 2, is arranged below the seating plane S. A possible two-part design of the seat 4 can be avoided in that the backrest 3 has an S-shaped design. That is, the backrest 3 also has a slightly concave bend 13 at its lower end, near the first, lower axis A-i, which adapts to the shape of the seat 4 at the rear end.

Otherwise, this embodiment is functionally essentially identical to the embodiment shown in FIGS. 1a and 1b. In the supporting position according to FIG. 4b, the inclination N of the backrest part 5 is between 0 ° and 60 °, preferably between 5 ° and 45 ° relative to the horizontal H. Such an inclination has proven to be particularly suitable for a standing leaning or supported position. The specified ranges for the inclination apply in the present case to all of the illustrated embodiments. The first, lower axis Ai can be arranged in a stationary or displaceable manner on the backrest support 2. The lower end of the Gegenlehnteils 5 is on the third, central axis A ₃ rotatably and stationary or else displaceably arranged on the counter-backrest part carrier 6 (see double arrow in FIG. 4b).

A fifth embodiment of the present invention is illustrated in FIGS. 5a and 5b. The first, lower axis A-i, via which the backrest 3 is articulated and rotatably coupled to the backrest support 2, is preferably arranged again above the seat plane. Furthermore, the first, lower axis Ai can be arranged in a stationary or displaceable manner on the backrest support 2.

What is special about this embodiment is that the backrest part support 6 comprises an extension piece 14 which can be _{pivoted upwards about the preferably stationary, third axis A 3} (as indicated by the dashed arrow in FIG. 5b). The extension piece 14 takes along the movable, fourth axis of rotation A ₄ , about which the lower end of the backrest part 5 rotates while it is folded out into its essentially horizontal support position according to FIG. 5b. The extension piece 14 then preferably stands essentially vertically upwards. However, angled positions of the extension piece 14 are also conceivable. In the sitting position shown in FIG. 5 a, the extension piece 14 is preferably received in the counter-backrest part 5.

The upper end of the backrest part 5 is coupled to the backrest 3 via the movable, second axis A _2. The movable, second axis A ₂ can be arranged in the backrest 3 or behind the backrest 3. It can furthermore be arranged displaceably in and / or relative to the backrest 3. Overall, a particularly stable and safe sitting position can be achieved by means of this embodiment, since the center of gravity of the respective user is shifted further in the direction of the central axis X.

Finally, a sixth embodiment of the present invention is illustrated in FIGS. 6a and 6b. The axis A _{3 is} preferably designed to be stationary on the backrest part carrier 6, a support piece 15 being provided for the backrest part 5, the support piece 15 being rotatably mounted on the backrest part carrier 6 _{about the axis A 3.} The backrest part 5 can be displaced to a limited extent (for example by means of suitable stops), preferably slidably, on or on the support piece 15. If the backrest 3 is now folded about the axis Ai in the direction of the vertical axis X, the backrest 3 takes the backrest _{part 5 coupled to it via the axis A 2} with it, so that it is displaced relative to the support piece 15 (cf. Double arrow), the support piece 15 rotating _{about the axis A 3 at the same time.} The axis A ₃ here represents the second support point of the backrest part 5. In the support position shown in FIG. 6b, the backrest part 5 is again aligned essentially horizontally or slightly inclined.

In principle, it is also conceivable that the axis A ₃ and with it the support piece 15 and the backrest part 5 are also arranged on the backrest part carrier 6 so as to be vertically movable.

In principle, for aesthetic reasons and for safety considerations (e.g. due to possible risk of injury), all of the folding mechanisms shown and described here can be designed to be retractable in the backrest or a corresponding backrest body.

Although the invention is illustrated and described in detail by means of the figures and the associated description, this illustration and this detailed description are to be understood as illustrative and exemplary and not as limiting the invention. In order not to obscure the invention, in certain instances well-known structures and techniques may not have been shown and described in detail. It is understood that those skilled in the art can make changes and modifications without departing from the scope of the following claims. In particular, the present invention covers further exemplary embodiments with any combination of features that may differ from the explicitly described feature combinations.

The present disclosure also encompasses embodiments with any combination of features that are mentioned or shown above or below for various embodiments. It also includes individual features in the figures, even if they are shown there in connection with other features and / or are not mentioned above or below. The alternatives of embodiments and individual alternatives whose features are described in the figures and the description can also be excluded from the subject matter of the invention or from the disclosed subject matter. The revelation includes Embodiments that exclusively include the features described in the claims or in the exemplary embodiments, as well as those that include additional other features.

In the following, the expression “comprise” and its derivatives do not exclude other elements or steps. Likewise, the indefinite article “a” or “an” and its derivatives do not exclude a large number. The functions of several features listed in the claims can be fulfilled by one unit or one step. The mere fact that certain measures can be listed in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. The terms “essentially”, “approximately”, “approximately” and the like in connection with a property or a value also define, in particular, precisely the property or precisely the value. The terms “about” and “approximately” in connection with a given numerical value or range can refer to a value or range that is within 20%, within 10%, within 5% or within 2% of the given value or range.

List of reference symbols:

1 chair

2 back supports

3 backrest 4 seat

5 backrest part

6 backrest part supports

7 base (base)

8 castors 9 perch

10 hydraulic cylinders

11 guide (in backrest)

12 guide (in counter-backrest part support)

13 lower bend backrest 14 extension piece

15 support piece

Ai first, lower axis (backrest / backrest)

A ₂ second, upper axis (backrest / backrest part)

A ₃ third, middle axis (counter-backrest part carrier / counter-back part) A ₄ fourth, movable axis (extension piece / counter-back part carrier)

H horizontal

S seating level

X vertical axis (central axis)

Claims

EXPECTATIONS

Claim 1: Chair with a seat (4), a backrest support (2) and a backrest (3), the backrest support (2) being mounted on the seat (4) and the backrest (3) on the backrest support (2), and the Chair (1) is designed so that in a sitting position a user can sit on the seat (4) and lean his back against the backrest (3), characterized by a backrest part (5) different from the backrest (3) The backrest (3) is tiltably connected to the backrest support (2) so that it can be folded from the sitting position into a supporting position in the direction of the seat (4), and the counter-back part (5) is coupled to the backrest (3) in such a way that the backrest (3) aligns the backrest part (5) when folding from the sitting position into the supporting position so that the user can support his buttocks on the backrest part (5).

Claim 2: Chair according to Claim 1, the backrest (3) being tiltably connected to the backrest support (2) in that it is mounted on the backrest support (2) so as to be pivotable about a first axis (Ai).

Claim 3: Chair according to Claim 1 or 2, the backrest part being coupled to the backrest (3) by being mounted on the backrest support (2) so as to be rotatable about a second axis (A2).

Claim 4: Chair according to claims 2 and 3, wherein the first axis (Ai) is arranged below the second axis (A2). Claim 5: Chair according to Claim 3 or 4, the counter-rest part (5) being coupled to the backrest (3) in such a way that the second axis (A2) can be displaced along the backrest (3).

Claim 6: Chair according to one of the preceding claims, the one

Comprises the backrest part carrier (6), wherein the backrest part carrier (6) is designed to be essentially stationary with respect to the backrest carrier (2).

Claim 7: Chair according to claim 6, wherein the backrest part (5) on

Counter backrest part support (6) is mounted so that it extends between the backrest part support (6) and backrest (3).

Claim 8: Chair according to claim 7, wherein the backrest part (5) is tiltably mounted on the backrest support (6) so that it can be moved from a quasi upright position to an inclined position when the backrest (3) moves from the sitting position to the support position works.

Claim 9: Chair according to claim 7 or 8, wherein the backrest part (5) is designed to be bendable so that it is curved from a quasi upright position to an inclined position when the backrest (3) folds from the sitting position into the supporting position.

Claim 10: Chair according to Claim 9, the backrest part (5) being at least partially elastic so that it can be bent.

Claim 11: Chair according to Claim 9 or 10, the backrest part (5) being at least partially designed like a roller shutter so that it can be bent.

Claim 12: Chair according to one of claims 7 to 11, wherein the backrest part (5) is slidably mounted on the backrest part carrier (6) so that it is shifted to the backrest part carrier (6) when the backrest (3) from the sitting position to the support position works. Claim 13: Chair according to Claims 11 and 12, the counter-backrest part carrier (6) being equipped with a guide (12) in which the counter-backrest part (5) is held displaceably.

Claim 14: Chair according to one of Claims 1 to 8, which _{comprises a support piece (15) rotatably arranged on the backrest part carrier (6) about an axis (A 3} ), the backrest part (5) being slidably guided on the support piece (15).

Claim 15: Chair according to one of the preceding claims, which has an underframe (7) on which the seat (4) is mounted, the underframe (7) being equipped with castors (8) for placing on a floor, which are braked are.

Claim 16: Chair according to one of the preceding claims, which has a sitting direction in which the user can sit down on the seat (4), and a support direction in which the user can support his buttocks on the backrest part (5), the sitting direction and the direction of support are virtually opposite.