EP2844109B1 - Chair, in particular office chair - Google Patents

Description

The invention relates to a chair, in particular an office chair having the features of the preamble of claim 1.

Such a chair is for example from the EP 2 173 218 B1 refer to.

Modern office chairs are usually equipped with a so-called synchronous mechanism, which ensures a correlated movement of a seat and a backrest with a tilt of the backrest, in such a way that at the same time with a tilt of the backrest, a rear seating area is also inclined.

The synchronizing mechanism is usually below the seat in a carrier unit, here referred to as base carrier unit integrated. This support unit is usually mounted on a support beam and connected via this with a pedestal. Basically, various designs of synchronous mechanisms are known. Mechanisms with an automatic weight adjustment are also known in which the restoring force acting on the backrest automatically adapts to the weight of the respective current user. An example of an office chair with synchronous mechanism and an automatic weight adjustment is from the mentioned EP 2 173 218 B1 refer to.

Furthermore, the EP 2 100 539 A1 to a chair having a seat surface, a backrest, wherein the backrest is pivotally connected to the seat surface, and a support structure that is pivotally connected to a seat surface support.

Proceeding from this, the object of the invention is to provide such a chair, which is equipped in particular with a synchronous mechanism, with improved comfort properties.

The object is achieved with a chair with the features of claim 1.

The chair, in particular an office chair, then comprises a seat mounted on a base support unit and a backrest having a lower backrest area and has an upper shoulder portion and which is attached to a backrest support. The backrest support is in particular approximately J-shaped and rotatably mounted on the base support unit about an inclination axis. The base support unit itself in turn preferably carries the synchronous mechanism and a seat-forming upholstered seat support. Furthermore, the shoulder area on the one hand articulated to the backrest support and on the other hand hinged to the lower backrest area. The shoulder area is tiltable about a shoulder axis. In that regard, a first articulated connection is formed between the shoulder region and the backrest support. The articulated connection of the lower backrest area to the shoulder area takes place in a lordosis area of the backrest. Shoulder area and lower back area are therefore quasi a transverse axis, hereinafter referred to as Lordosenachse, attached via a second hinge connection to each other. Finally, the lower backrest area continues to be guided on a chair element, preferably the backrest support or the seat.

Due to the positive guidance of the lower backrest region at its lower end, connected to the joint connection between the shoulder region and the lower back region and the pivotability of the shoulder region about the shoulder axis, a mechanical positive guidance is achieved such that, given an inclination of the shoulder region about the shoulder axis, the angular orientation of the shoulder region varies relative to the lower back area and in particular the lordosis of the backrest forward, ie towards the seat, is curved (at an inclination of the shoulder area about the shoulder axis from an upright position to a reclined position). At the same time the lower backrest area is guided at its lower pivot point on the seat or on the backrest support. The articulation or guide at the lower end of the lower backrest region therefore serves in particular for length compensation in the case of the inclination of the backrest about the shoulder axis. Overall, this positive guide allows bulging the backrest in the lumbar region forward. As a result, the overall comfort of the chair is increased.

The backrest has a central region and laterally adjacent thereto each have a lateral area, which are directed to better lateral guidance forward, ie towards the seat. This orientation of the lateral regions in relation to the central region is also forcibly changed with an inclination of the shoulder region about the shoulder axis. In such a way that, with an inclination of the shoulder region towards the rear, the lateral regions virtually swing forward and thus provide improved lateral guidance. So there is a total of a synchronous, positively driven movement such that in the lumbar region of the body undergoes support and at the same time lateral areas are led forward for a better lateral guidance.

In order to enable the pivoting of the lateral areas to the front they are pivotable relative to the central region. Therefore, the backrest itself has areas on its side, which are folded over joints with a vertical orientation to the front or at least bent. Therefore, in addition to the typically horizontal articulated connection between shoulder region and lower back region, two substantially vertical articulated connections between the respective middle region and the lateral regions are also formed on the backrest itself. These articulated connections can be formed by elastic (bending) areas or by joints.

The lower backrest area is also pivotally connected to the seat. Due to the direct connection of the backrest to the seat, improved guidance of the body over all inclination positions is achieved in the transition region between the seat and the backrest.

Conveniently, the seat in this case has a rear seat part, which is hinged to a front seat part. The two seat parts are about an axis, hereinafter referred to as seat axis, rotatably supported by a corresponding hinge connection together. About this articulated connection the rear seat part on the one hand with the front seat part and on the other hand with the lower backrest area is carried out in a simple manner a length compensation at an inclination of the shoulder area about the shoulder axis, in which the lower backrest area is pulled upwards towards the shoulder axis. By this measure, therefore, the rear seat part is pulled over the lower backrest area upwards with an inclination of the shoulder region to the rear and thus supports the body in the transition region between the seat and backrest.

At the same time increases this pivotal mounting of the rear seat part, the comfort even with a tilt of the backrest total about the inclination axis, so if the backrest is tilted about the inclination axis on the base support to the rear. Also in this movement, an advantageous forced operation of the rear seat area. The two seat parts are usually provided by plates or shells, ie mechanically rigid units of the seat support, on which the seat upholstery is applied.

With regard to the greatest possible comfort while the seat axis is on the one hand behind the tilt axis, ie oriented towards the backrest. Furthermore, the seat axis and / or preferably also the inclination axis, arranged close to a body rotational axis, which is defined in particular by the hip joint. As a result, Relatiwerschiebungen between body and seat or backrest are kept as low as possible at an inclination.

In an expedient development, the shoulder region is followed by another upper back region, which serves for head support and can also be referred to as the head region. Also, this backrest area is connected to the shoulder area, in an expedient embodiment also articulated. In a further embodiment, it is provided that also the upper backrest region has laterally swing-away partial areas, which are likewise connected to the other side areas. Overall, this results in a forced operation and a forced folding the side areas forward.

The shoulder area is arranged counter to a restoring force on the backrest support tiltable about the shoulder axis. This is preferably formed by a spring element or a resilient design of the joint between the backrest support and the shoulder area. Preferably, for example, a spring element is arranged between the backrest support and the backrest, which exerts a restoring force on the shoulder region. The spring element is formed, for example, as a clamped between backrest support and backrest elastic element, a (pressure) spring or by integral training in the hinge connection. The restoring force is expediently adjustable.

The backrest is formed in accordance with a first preferred embodiment variant by a circumferential and with a fabric, such as a net fabric, covered frame. In the shoulder region, this has upper, lateral frame parts and lower, lateral frame parts in the lower back region, wherein the frame parts are connected to one another in an articulated manner. The upper and lower frame parts are preferably arranged at an angle to each other in such a way that in the lumbar region and thus in particular in the region of the hinge connection between the upper shoulder region of the backrest and the lower backrest region of the frame is deflected forward to the seat. In this deflection the articulation and thus the Lordosenachse is formed. Usually, the lateral frame parts are - viewed in a rear view - also formed laterally outwardly extending at an angle.

The frame further has a lower and an upper transverse strut, which are in particular bent. The upper transverse strut is preferably articulated to the backrest support so that the articulated connection between the shoulder region and the backrest support is formed via this connection.

The cross struts are still articulated in an expedient embodiment and in particular connected to the above-mentioned vertical axes with the upper frame part or lower frame part. Due to the articulated connection The cross braces is therefore created the possibility that the lateral frame parts swivel inward with an inclination of the shoulder region or swivel outwards again in reverse movement sequence. This movement takes place forcibly due to the constraining forces acting on the frame during the tilt adjustment. These lead on the one hand to the fact that the lateral frame parts can bend each other, so that the lumbar area is bulged forward. At the same time they lead to the fact that the two frame parts are pivoted in relation to the transverse struts, that they are thus pivoted towards each other and to a central region. This results in the desired support in the lumbar region and the additional lateral support in the side areas.

The frame is formed in particular only peripherally circumferentially, therefore, has no further support struts for supporting the body. The body support takes place exclusively through the fabric cover. The transverse struts, in particular the upper cross member, are bent back and preferably do not support the body.

However, at the same time to ensure a mechanically reliable support of the lordosis in the lumbar region, a lumbar support is additionally arranged, which is connected to the lower cross member. It is preferably mechanically non-rotatably connected, so that the lumbar support automatically follows a movement of the transverse strut. Due to the required length compensation in a buckling of the lumbar region forward usually takes place automatically a rotation of the lateral lower frame part. At this the cross strut is mechanically firmly connected, so that the angular orientation of the lower frame part is transmitted via the lower crossbar on the lumbar support.

In order to allow a structurally simple design of the joints between the individual frame sections, ie between the two side frame parts and between them and the cross struts, are preferred for forming these joints each notches in Frame trained. The frame is formed overall as a one-piece frame, for example as a cast or molded plastic part. The frame is therefore formed in defined areas by material reductions bending elastic.

In a preferred development, in addition to the shoulder area, an upper backrest part for the head support is also formed, which is defined by an additional upper frame, which is preferably also formed integrally with the rest of the frame. This upper frame receives the upper transverse strut and its lateral frame parts adjoin the lateral frame parts of the shoulder region, in particular on the joint connections defined over the vertical axes.

According to a second preferred embodiment variant, the backrest has a plurality of backrest elements pivotably secured together, namely at least one main backrest element defining the shoulder region, and a lower backrest element which is hinged to the lower end of the mainback element and which forms the lower backrest region. The individual backrest elements are plate-shaped or cup-shaped or have such. In this embodiment, therefore, the backrest is mosaic-like formed from a plurality of interconnected, plate-like backrest elements. In order to form the lateral regions, in each case lateral cheek elements are preferably hinged to the main backrest element and to the lower backrest element. These are in turn formed by plates or shells or have such and are also articulated to each other, so that at an inclination forced guidance and forced movement results in such a way that the lateral cheek elements are deflected at an inclination about the shoulder axis forward.

Preferably, in addition to the head support in the middle of an upper backrest element and further preferably laterally thereto further cheek elements are formed, which are hingedly connected to the upper back element and at the same time hinged to the cheek elements of the shoulder area.

In order to enable the desired positive guidance in the simplest possible way, while the individual backrest elements are each wedge-shaped or trapezoidal in shape, wherein adjacent backrest elements are each arranged in an advantageous manner fallen to each other. Both the shoulder region and the lower back region are therefore each formed by three separate backrest elements, which are preferably each formed trapezoidal and fallen to each other. At the same time, the mutually adjacent trapezoidal elements between the shoulder region and the lower back region are also collapsed with respect to one another, so that long sides or short sides are respectively arranged opposite one another. The trapezoidal configuration is chosen in particular such that the central region between the cheek elements is tapered in the lordosis. At the same time, the cheek elements are widened in this area.

The adjoining edges of the backrest elements each define the joints. Due to the approximately trapezoidal or wedge-shaped configuration, therefore, the vertical axes between the central backrest elements and the cheek elements do not run exactly in the vertical direction. If the present case is therefore referred to as a vertical axis, this is merely an approximately vertical orientation, in which a deviation from the exactly vertical alignment of, for example, +/- 30% is made possible. This applies to both variants.

The individual backrest elements are expediently hinged to each other at their adjoining sides or edges in the manner of film hinges. For this purpose, the backrest elements are formed according to a first variant as a single separate plates or shells in a preferred embodiment. These are connected to each other either by a respective elastic flat hinge strip, for example a textile or rubber-elastic material. Alternatively, they are used in a large-area, in particular the entire surface of the backrest elements covering elastic cover (padded cover). It can be sewn into this cushion cover pockets into which the individual plate-shaped backrest elements are inserted.

Alternatively, a plurality of the back elements, in particular the entire backrest, are formed by a one-piece plastic part (for example injection molding). The individual backrest elements are connected to each other via material bridges, i. delimited by notches or material tapers in the one-piece part of each other. These notches at the same time define articulated joints designed in the manner of film hinges. This one-piece plastic backrest is then usually covered with a cushion.

Fig. 1

eine perspektivische Vorderansicht eines Bürostuhls gemäß einer ersten Ausführungsvariante,

Fig. 2

eine Rückansicht des Bürostuhls gemäß Fig.1,

Fig.3

eine Seitenansicht des Bürostuhls gemäß Fig.1 bei normaler, aufrechter Position der Rückenlehne,

Fig. 4

eine Seitenansicht des Bürostuhls gemäß Fig. 1 mit geneigter Rückenlehne,

Fig. 5

eine ausschnittsweise, perspektivische Seitenansicht eines Bürostuhls gemäß einer zweiten Ausführungsvariante,

Fig. 6

eine perspektivische Seitenansicht des Bürostuhls gemäß Fig. 5, bei der lediglich ein Schulterbereich der Rückenlehne etwas nach hinten geneigt ist,

Fig. 7

eine perspektivische Seitenansicht des Bürostuhls gemäß Fig. 5, wobei im Vergleich zu der in Fig.5 dargestellten Situation die Rückenlehne insgesamt um eine Neigungsachse nach hinten und ergänzend der Schulterbereich der Rückenlehne um eine Schulterachse nach hinten geneigt ist,

Fig. 8

eine modifizierte Ausführungsvariante eines Bürostuhls in perspektivischer Seitenansicht, bei dem ergänzend zu der in Fig. 5 dargestellten Ausführungsvariante eine zusätzliche Lordosenstütze angeordnet ist.

Embodiments of the invention will be explained in more detail with reference to FIGS. These show:

Fig. 1

3 is a front perspective view of an office chair according to a first embodiment;

Fig. 2

a rear view of the office chair according to Fig.1 .

Figure 3

a side view of the office chair according to Fig.1 in normal, upright position of the backrest,

Fig. 4

a side view of the office chair according to Fig. 1 with inclined backrest,

Fig. 5

1 a partial, perspective side view of an office chair according to a second embodiment variant,

Fig. 6

a perspective side view of the office chair according to Fig. 5 in which only one shoulder region of the backrest is inclined somewhat backwards,

Fig. 7

a perspective side view of the office chair according to Fig. 5 , where compared to the in Figure 5 illustrated situation, the backrest as a whole about an inclination axis to the rear and, in addition, the shoulder region of the backrest is inclined to the rear about a shoulder axis,

Fig. 8

a modified embodiment of an office chair in a perspective side view, in addition to the in Fig. 5 illustrated embodiment, an additional lumbar support is arranged.

In the figures, like-acting parts are each provided with the same reference numerals.

The office swivel chair shown in the figures has in both embodiments, each a base support unit 2, to which a seat 4 and a backrest support 6 are attached. The backrest support 6 is rotatably mounted on the base support unit 2 about an inclination axis A1. The base support unit 2 receives a synchronous mechanism, not shown here. Also included in it is a mechanism for weight adjustment. This can be designed as an automatic weight adjustment or as a manually adjustable weight setting.

On the backrest support 6, a backrest 8 is fixed, which is divided into several subregions. Thus, it has an upper shoulder region 10 and a lower back region 12. In both embodiments, an upper back region 14 forming a head region adjoins the upper shoulder region 10.

Overall, the backrest 8 has a central region 16, to each side of which a lateral region 18 connects.

The shoulder region 10 and the lower back region 12 adjoin one another in a lordosis region 20 and are attached to one another via an articulated joint in an articulated manner. They can therefore be inclined to each other about a common axis, hereinafter referred to as lordosis axis A2, so that their angular orientation to each other changes.

The shoulder region 10 in turn is connected in an articulated manner to the backrest support 6 via a further articulated connection, which permits an inclination of the shoulder region 10 about a horizontal axis, referred to below as a shoulder axis A3. In addition, lateral, substantially vertically extending vertical axes, namely an upper vertical axis B2 in the shoulder region 10 and a lower vertical axis B2 in the lower back region 12, are formed. The vertical axes B1, B2 allow pivoting of the lateral areas 18 forward towards the seat 4th

In both embodiments, the backrest 8 is mechanically connected directly to the seat 4. In addition to the indirect connection via the backrest support 6 and the base support unit 2, therefore, a direct connection between the backrest 8 and the seat 4 is formed. For this purpose, the seat 4 has a rear, plate-shaped seat part 22, which is mechanically connected to the lower backrest region 12. The connection takes place in particular via an articulated connection, wherein at least a certain pivoting mobility is made possible around a connecting axis A4. The rear seat part 22 itself is pivotally attached to a front seat part 24 via a further articulated connection about a seat axis A5. The two seat parts 22,24 are plate-shaped or cup-shaped and form in particular a two-part seat support, which ultimately carries the padding.

With the help of an effective between the backrest support 6 and the backrest 8 spring element 26 (see 3 and 4 ), a restoring force is exerted on the shoulder region 10 with respect to its inclination adjustment about the shoulder axis A3.

In the in the Fig. 1 to 4 illustrated embodiment, the backrest 8 is formed by a plurality of plate-like or shell-shaped back elements, namely a main backrest element 28, which forms the central region of the shoulder region 10, a lower back element 30, which forms the central lower back region 12, an upper back element 32, which is the middle upper Lehnenbereich 14 forms. These three backrest elements 28,30,32 are each connected to each other via horizontally extending joints. The main backrest element 28 and the lower backrest element 30 are connected to one another in an articulated manner about the lordosis axis A2. The upper backrest element 32 is connected to the main backrest element 28 about a head axis A6 tiltably connected to the main backrest element 28.

To each of these backrest elements 28 to 32, a side cheek element 34 connects. These are each hingedly connected to adjacent cheek elements 34. As in particular from the side representations of the 3 and 4 As can be seen, the cheek elements 34 extend laterally forward in the direction of the seat 4, are therefore oriented at an angle to the back elements 28 to 32 of the central region 16.

The individual backrest elements 28 to 34 each have a trapezoidal or wedge or triangular base surface, so that they taper from a long side to a short side or taper to a point. The individual backrest elements 28 to 34 are each arranged in a downward position with respect to each other, so that - viewed in the vertical direction - adjacent backrest elements 28 to 34 abut each other on their long sides and short sides, respectively. As a result, a waist is formed in the lumbar region 20. At the same time, the cheek elements 34 are here pulled laterally forward.

• Bei einer Neigung des Schulterbereichs 10 nach hinten (ausschließlich) um die Schulterachse A3 wird aufgrund der gelenkigen Verbindung zum unteren Lehnenbereich 12 dieser zum einen etwas nach oben gezogen und gleichzeitig auch nach vorne in Richtung zum Sitz 6 ausgelenkt, wodurch eine gewünschte Unterstützung im Lordosenbereich 20 erzielt ist. Gleichzeitig erfolgt aufgrund der mechanischen Ankopplung der Wangenelemente 34 und insbesondere auch aufgrund der speziellen trapezförmigen Geometrie der einzelnen Elemente 28 bis 34 ein Einklappen der Wangenelemente 34 nach vorne in Richtung zum Sitz, so dass zusätzlich auch eine verbesserte Umfassung des Oberkörpers und damit eine bessere seitliche Führung erfolgt. Aufgrund der Auswölbung der Rückenlehne 8 im Lordosenbereich 20 nach vorne ist ein Längenausgleich im Bereich des unteren Lehnenbereichs 12 erforderlich.

The operation of the chair according to the first embodiment of the Fig. 1 to 4 is as follows:

• With an inclination of the shoulder region 10 to the rear (exclusively) about the shoulder axis A3 due to the articulated connection to the lower backrest region 12, this pulls up slightly and at the same time deflects forwards toward the seat 6, whereby a desired support in the lumbar region 20 achieved. At the same time due to the mechanical coupling of the cheek elements 34 and in particular due to the special trapezoidal geometry of the individual elements 28 to 34 folding the cheek elements 34 forward toward the seat, so that in addition an improved enclosure of the upper body and thus better lateral guidance he follows. Due to the bulge of the backrest 8 in the lumbar region 20 forward a length compensation in the region of the lower backrest portion 12 is required.

This is done by the articulated connection of the lower backrest portion 12 with the rear seat portion 22 and its hinged connection to the front seat portion 24. The rear seat portion 22 is in the connection region to the lower backrest portion 12, ie in the region of the connecting axis A4, at an inclination of the shoulder region 10th pulled backwards in about vertical direction. At the same time there is a pivotal movement of the rear seat portion 22 relative to the front seat portion 24. The rear seat portion 22 is therefore obliquely upward tracked as soon as an inclination of the shoulder portion 10 about the shoulder axis A3. The shoulder axis A3 is generally formed approximately in the upper third of the shoulder region.

Usually, a tilt adjustment of the shoulder region 10 takes place simultaneously with an inclination position of the entire backrest 8 relative to the base support unit 2, that is, at an inclination of the backrest support 6 about the inclination axis A1. Such a combined inclination in Fig. 4 compared to Fig. 3 shown. Starting from the in Fig. 3 illustrated starting position with the backrest support 6 in an upright basic position, carried out at a tilt adjustment in the Fig. 4 indicated by the arrows 36 rotational movements of the individual elements about the respective axes A1 to A6.

Due to the inclination of the backrest 8 about the inclination axis A1, the shoulder region 10 is pulled obliquely rearward on the shoulder axis A3. This is done in comparison to the in Fig. 3 illustrated initial stretch of the backrest, so so that the shoulder region 10 about the shoulder axis A3 is inclined towards the front seat 4, whereby the angle between the shoulder region and the lower back region 12 is increased. As a result, the rear seat part 22 is pulled down in the direction of the backrest support 6 overall. The angle between the rear seat portion 22 and the lower backrest portion 12, which at the in the Fig. 3 shown starting position is almost at right angles, is slightly reduced.

Overall, therefore, an interconnected joint or link chain is formed by the individual axes A1 to A6, which at a tilt adjustment leads to a desired forced adaptation of the contour of the backrest 8.

Due to the extension of the backrest, in which therefore the lumbar region 20 is displaced backwards in the direction of the backrest support 6, compulsory compensation in the lateral regions 8 is brought about at the same time, so that the individual cheek elements 34 extend about the vertical axes B1, B2 and additionally around one another fold in the third vertical axis B3 in the upper backrest area 14 to the front.

In a return of the backrest 8 in the upright sitting position of the movement takes place in the reverse order. The spring force of the spring element 26 is oriented such that it is an extension of the backrest 8 in the transition from the upright position in the in Fig. 4 shown inclined position counteracts.

The second in the Fig. 5 to 8 illustrated embodiment, the operation is basically the same. Again, therefore, a link chain or link chain is formed, which leads to a forced operation and forced adaptation of the contour of the backrest at an inclination. However, no individual back elements 28 to 34 are formed here. The backrest 8 rather consists of a frame 38, which is formed by lower frame parts 40 in the lower back region 12, upper frame members 42 in the shoulder region 10, a lower cross member 44 and an upper cross member 46. In the embodiment, the upper cross member 46 also forms a lower cross member a head frame 48 in the region of the upper backrest region 14. The head frame 48 has, in continuation of the upper frame parts 42, opposite side parts 50 and a further, uppermost transverse strut 52. In particular, the upper transverse strut 46 and the further, uppermost transverse strut 52 are in this case bulged towards the rear. The frame parts 40,42 are - viewed from the side - arranged at an angle to each other, so that the lumbar region 20 is bulged forward.

The frame 38 is covered with a fabric 54 as a whole. To form the lordosis axis A2 are in the frame 38 notches, ie material tapers 56, trained. For the formation of the two vertical axes B1, B2 corresponding, vertically oriented indentations 56 are formed at the transition of the upper frame part 42 to the upper transverse strut 46 and the lower frame part 40 to the lower transverse strut 44.

The upper cross member 46 is connected to a front end of the backrest support 6, wherein at this connection point a pivoting movement between the upper cross member 46 and the backrest support 6 is made possible, whereby the shoulder axis A3 is defined.

In the embodiment of the Fig. 8 is additionally a lumbar support 58 arranged, which is rotatably connected via a retaining web with the lower cross member 44.

The Fig. 5 shows the unloaded starting position with upright backrest 8. Starting from this unloaded starting position shows Fig. 6 a position in which only an inclination of the shoulder portion 10 about the shoulder axis A3 takes place (no inclination about the inclination axis A1). That is, the head frame 48 has tilted backward and is now in an approximately upright position after the head frame 48 was previously inclined forward. The fabric 54 is therefore pulled slightly upwards overall. The required length compensation takes place via the rear seat part 22, which is pulled up around the seat axis A5. At the same time a change in the angular position between the rear seat part 22 and the lower backrest part 12 can take place, which are preferably held elastically to each other about the connecting axis A4. In the embodiment takes place in this illustrated movement, starting from the Fig. 5 towards the Fig. 6 no change in the angular position between the two frame parts 40,42. So there is no rotation around the lordosis axis A2.

The Fig. 7 shows finally a superimposed combined tilt adjustment, in which both the shoulder area 10 - as in Fig. 6 - Is tilted to the rear about the shoulder axis A3 and at the same time also the total backrest 8 about the inclination axis A1 is tilted backwards. Similar to the situation in the first embodiment according to Fig. 4 In this case, a stretching of the backrest 8 down, wherein the rear seat part 22 in comparison to the in Fig. 5 pivoted downwards starting situation shown. At the same time, the shoulder region 10 tilts backwards. As a result of this stretching, the lateral frame parts 40, 42 inwardly swivel inward about the vertical axes B1, B2 and provide better lateral guidance.

In the embodiment according to the Fig. 8 the lordosis in the lordosis area 20 is additionally supported by the lumbar support 58. LIST OF REFERENCE NUMBERS 2 Based support unit A1 tilt axis 4 Seat A2 Lordosenachse 6 backrest support A3 shoulder axis 8th backrest A4 connecting axis 10 upper shoulder area A5 seat axis 12 lower backrest area A6 head axis 14 Upper backrest area B1 upper vertical axis 16 mid-range B2 lower vertical axis 18 lateral area 20 lordosis 22 rear seat part 24 front seat part 26 spring element 28 Main rest element 30 lower back element 32 Upper backrest element 34 cheeks element 36 arrow 38 frame 40 lower frame part 42 upper frame part 44 lower crossbar 46 upper cross strut 48 head frame 50 side panel 52 further cross strut 54 material 56 notches 58 lumbar support

Claims (14)

1. Chair, in particular office chair, with a seat (6) fastened to a base support unit (2), with a backrest (8), which has a lower backrest region (12) and an upper shoulder region (10) and which is fastened to a backrest support (6), which is rotatably mounted on the base support unit (2) about an inclination axis (A1), wherein
   the shoulder region (10) is connected to the backrest support (6) in an inclinable manner about a shoulder axis (A3) and is also hinged to the lower backrest region (12) in a lumbar region (20) and that the lower backrest region (12) is further guided on a chair element (22), in such a way that a change of the angular orientation of the shoulder region (10) relative to the lower backrest region (12) is allowed while the shoulder region (10) is inclined about the shoulder axis (A3), wherein the lower backrest region (12) is hinged to the seat (6),
   characterised in that
   the backrest (8) has a middle region (16) and also, adjacent to this, lateral regions (18), which are directed forwards for lateral guidance, wherein the orientation of the lateral regions (18) in relation to the middle region (16) is changed in a positively guided manner while the shoulder region is inclined, and characterised in that the lateral regions (18) are swivellable about vertical axes (B1, B2) in relation to the middle region (16).
2. Chair according to one of the preceding claims, characterised in that the seat (6) has a rear seat part (22), which is hinged to a front seat part (24).
3. Chair according to one of the preceding claims, characterised in that an upper backrest region (14) to support the head adjoins the shoulder region (10), whereby the upper backrest region is connected more particularly in a hinged manner to the shoulder region (10).
4. Chair according to one of the preceding claims, characterised in that there is disposed between the backrest support (6) and the backrest (8) an effective spring element (26), which exerts a restoring force onto the shoulder region (10) in relation to its hinged connection on the backrest support (6).
5. Chair according to one of the preceding claims, characterised in that the backrest (8) has a frame (38) around it that is covered with a material (54), said frame has upper frame parts (42) in the shoulder region (10) and lower frame parts (44) in the lower backrest region (12).
6. Chair according to claim 5, characterised in that the frame (38) has a lower cross-member (44) and an upper cross-member (46), where the upper cross-member (46) is hinged to the backrest support (6).
7. Chair according to claim 5 or 6, characterised in that the frame (38) has an upper and a lower cross-member (44, 46), each of which is hinged to either the upper frame part (42) or the lower frame part (40) in such a way that the frame parts (40, 42) swivel inwards or outwards, respectively, when the shoulder region (10) is inclined about the shoulder axis (A3).
8. Chair according to one of claims 5 to 7, characterised in that a lumbar support (58) is disposed, which is preferably connected with the lower cross-member (44) in such a way that it is mechanically unable to rotate.
9. Chair according to one of claims 5 to 8, characterised in that the hinged connections of the various parts of the frame (40-46) are achieved by way of notches (56).
10. Chair according to one of claims 1 to 4, characterised in that the backrest (8) has multiple backrest elements that are pivotably fastened to each other (28-34), namely at least a main backrest element (28), which defines the shoulder region (10), and a lower backrest element (30), which is pivotably fastened on the lower end of the main backrest element (28) and which forms the lower backrest region (12).
11. Chair according to claim 10, characterised in that cheek elements (34) are pivotably fastened on the sides of the main backrest element (28) and also of the lower backrest element (30), wherein the cheek elements (34) are likewise pivotably fastened to each other.
12. Chair according to one of claims 10 to 11, characterised in that the backrest elements (28-34) each have a wedge-shaped or trapezium-shaped area and the neighbouring backrest elements (28-34) are each disposed in alternate directions.
13. Chair according to one of claims 10 to 12, characterised in that the backrest elements (28-34) are connected pivotably with each other in the manner of living hinges.
14. Chair according to one of claims 10 to 13, characterised in that multiple backrest elements (28-34) are formed by means of a one-piece part, wherein the individual backrest elements (28-34) are connected with each other by means of living hinges formed as material bridges or that the backrest elements (28-34) are formed as separate plates, which are connected with each other optionally by means of an elastic hinge strip or by means of an extensive elastic cover, more particularly one covering the entire area of the backrest elements.

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