Office chair with an adaptable lumbar support

An office chair (1) including a seat (2), a backrest (3) including a lumbar support (4), an actuator device (8) arranged to enable adjustment of the lumbar support (4) between an inactive position in which it follows the general shape of the backrest (3), and a fully active position in which it is adjusted outwards forwardly from the backrest (3) in order to support the lumbar back portion of a person seated on the seat (2). The lumbar support (4) includes a first part (200) with first (201) and second (202) ends and a second part (300) with first (301) and second (302) ends. The first ends (201, 301) of the first and second parts (200, 300) are connected to each other via a pivoting point (400) and the second ends (202, 302) are pivotally coupled to the backrest (3), wherein at least one of the second ends (202, 302) of the parts (200, 300) is slidably arranged along the backrest (3) and wherein the actuator device (8) pushes and/or pulls the slidable ends (202, 302) in response to actuation.

This application is a national phase of International Application No. PCT/SE2013/050097 filed Feb. 6, 2013 and published in the English language.

FIELD OF THE INVENTION

The present invention relates to an office chair with an adaptable lumbar support.

BACKGROUND OF THE INVENTION

Traditionally, office chairs have been constructed by men for men. Even though over the last decades women are just as common as men in offices, this is to a great extent still true. Most chairs are adaptable to fit persons of different length and different weight, but the main features are still adapted for men. This invention is based on extensive studies of ergonomics as well as physical and social factors, from which it has been determined that there are differences in the way women and men are sitting in office chairs.

In WO2010/087760, an office chair is described in which a lumbar support is activated for supporting the lumbar back portion of a person seated on the chair when said person is leaning forward. This chair offers support for the everyday working position for persons working in an office.

However, it has been desired to develop the office chair in WO 2010/087760 even further, since the design of the lumbar support results in that the force for adjusting the lumbar support has to be increased continuously as the lumbar support is continuously curved from an inactive position to a fully active position. For minimising the resistance given by the padding and fabric in the backrest of the chair when the lumbar support is in motion, it is important to find a material with the appropriate thickness for the padding, and an appropriate fabric for the backrest of the chair, this is costly. To be able to generate forces high enough to overcome the resistance given by the lumbar support, the padding and the fabric in the backrest, when the lumbar support is adjusted from the inactive position to the fully active position, the actuator device will have a complex structure and will hence be expensive.

Thus, there is a need for a chair with a lumbar support that gives as little resistance as possible when adjusted between the inactive position and the fully active position and that is cheaper to manufacture than previously known chairs. The invention is based on this discovery and the inventive chair has been elaborated especially for women but can be made in any size and is not limited to fit persons of a certain size or figure.

SUMMARY OF THE INVENTION

An object of the invention is to provide a chair with an adaptable lumbar support that easily can be adjusted between the inactive position and the fully active position and that can be manufactured at a low cost. The above-mentioned object is achieved by the present invention according to the claim1.

According to a main aspect the invention relates to an office chair comprising a seat, a backrest including a lumbar support, an actuator device arranged to enable adjustment of the lumbar support between an inactive position in which it follows the general shape of the backrest, and a fully active position in which it is adjusted outwards forwardly from the backrest in order to support the lumbar back portion of a person seated. The lumbar support comprises of a first part with a first end and a second end and a second part with a first end and a second end, said first ends of said first and second parts are connected to each other via a pivoting point and said second ends are pivotally connected to the backrest, wherein at least one of said second ends of said parts is slidably arranged along the backrest wherein the actuator device is arranged to push and/or pull said slidable ends in response to actuation.

With the chair according to the invention the lumbar support will give less resistance when adjusted between an inactive position to a fully active position resulting in a more simple structure than previously known chairs with a lumbar support, and hence it can be manufactured at a lower cost than before.

Preferred embodiments of the invention are set forth in the dependent claims and in the detailed description.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENT OF THE INVENTION

FIGS. 1 and 2shows the general function of the office chair according to the shown embodiment of the invention.

The office chair1comprises a seat2and a backrest3. The backrest3includes a lumbar support4, which is adjustable between an inactive position (shown inFIG. 1) in which it follows the general shape of the backrest3, and a fully active position (shown inFIG. 2) in which it is adjusted outwards forwardly from the backrest3in order to support the lumbar back portion of a person seated on the seat2of the chair1. Further, the chair1comprises an adjustment device8(shown inFIG. 3-7) to enable adjustment of the lumbar support4. In all the embodiments shown in theFIG. 1-7, the adjustment device8is adjusted in response to tilting of the chair1. However, it is also possible to arrange the chair1so that the adjustment device8is adjusted in another way, e.g. in response to pulling or pushing a lever.

InFIGS. 3 and 4, it is shown that the seat2is tiltable about a pivot point A between a first position or an initial position (shown inFIG. 3), and a second slightly forwardly tilted position (shown inFIG. 4). The position of the seat2is adjusted by means of the centre of gravity G of a person seated in the chair, such that when the centre of gravity G is located behind the first pivot point A the seat2is in the initial position, and when the centre of gravity G is in front of the pivot point A the seat2is transferred into the tilted position. In the figures, the centre of gravity G of the person seated in the chair is represented by a chequered dot, which is to be compared with a vertical line A1corresponding to the vertical projection of the pivot point A.

Further, as indicated above, the position of the lumbar support4is governed by the position of the seat2such that it is positioned in the inactive position (shown inFIG. 3) when the seat2is in the first position, and in the active position (shown inFIG. 4) when the seat2rests in the second position, in order to support the lumbar back portion of a person seated on the seat2of the chair1when said person is leaning forwards. This may in fact be realised in a number of ways that are obvious to a person skilled in the art once the object of the invention have been established.

A general object of the invention is to facilitate the adjustment of the lumbar support4. According to the invention the lumbar support4comprises a first part200with a first end201and a second end202and a second part300with a first end301and a second end302. The first end201of the first part200is connected to the first end301of the second part300via a pivoting point400and the second end202of the first part200and the second end302of the second part300are both pivotally coupled to the backrest3. To enable the lumbar support4to be adjusted between the inactive position and the fully active position, one of or both of the second ends202,302of the first and second parts200,300, respectively, is slidably coupled to the backrest3. To enable a comfortable support of the lumbar back portion of a person seated on the chair even in the activated position, the lumbar support also comprises a back plate500.

The function of the lumbar support4, will now be described with reference toFIGS. 5, 6 and 7.

In the office chair1in the shown embodiment ofFIG. 5, a wire8is arranged between the seat2and the lumbar support4, a first end12of the wire is connected to second end202of the first part200of the lumbar support4and a second end13(seFIGS. 3 and 4) of the wire8is connected to the seat2of the chair1. InFIG. 5, the second end202of the first part200of the lumbar support4is slidably coupled to the backrest3and the second end302of the second part300and the lumbar support4is connected to the backrest3. When the seat is tilted from the initial position, the seat2pulls the first end12of the wire8, which results in that the second end13of the wire8is pulling the slidable second end202of to the first part200of the lumbar support4downwards, to position the lumbar support4in the active position.

In the office chair1in the shown embodiment ofFIG. 6, a wire8is arranged between the seat2and the lumbar support4, a first end12of the wire8is connected to the backrest3and the second end13of the wire8is connected to is the seat2of the chair1(seFIGS. 3 and 4). InFIG. 6the second end302of the second part300of the lumbar support4is slidably coupled to the backrest3and the second end202of the first part200of the lumbar support4is connected to the backrest3. The wire8is arranged inside a rigid sheath9such that it is free to move co-axially inside the sheath9, wherein the sheath9having two openings10,11, through which the ends12,13of the wire8extends. In this embodiment the wire8runs in a loop under the seat and said second end13of the wire8exits the second opening11of the sheath9and is attached to a fixing point14on a lever40(seFIGS. 3 and 4) on the underside of the seat2and the first end12of the wire8exits the first opening10of the sheath9and is connected to a fixing point15at the backrest3of the chair1. The function of the sheathed wire8is similar to the function of a shoe brake, used e.g. on bikes.

When the seat2is tilted from the initial position, the lever40is arranged to be activated when the seat2is tilted, wherein the lever40pulls the second end13of the wire8so that the wire8successively will exit the second opening11of the sheath9. In order for this to work, the sheath openings10,11need to restrict the sheath9from moving with the wire8. The easiest way to arrange this is of course to couple the openings10,11opposed to and in the vicinity of the respective fixture point14,15of the wire ends12,13. Since the sheath9is ridged and is restricted from moving with the wire8, and the loop of the wire8on the underside of the seat2is shortened when the lever40pulls the second end13of the wire8, the first opening10of the sheath9will move towards the first end12of the wire8and hence push the second end302of the slidable second part300of the lumber support4upwards, to position the lumber support4in the active position.

The embodiment of the office chair1inFIG. 7is similar to the embodiment inFIG. 6, but with the difference that both the second end202of the first part200of the lumber support4and the second end302of the second part300of the lumber support4are slidably arranged in the backrest3and that the first end12of the wire8is coupled to said second end202of the first part200of the lumber support4.

The present invention is not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the invention, which is defined by the appending claims.