WO1997007717A1

WO1997007717A1 - Improvements in/or relating to chairs

Info

Publication number: WO1997007717A1
Application number: PCT/NZ1996/000090
Authority: WO
Inventors: Mark Pennington
Original assignee: Formway Furniture Limited
Priority date: 1995-08-30
Filing date: 1996-08-30
Publication date: 1997-03-06
Also published as: AU4265700A; AU749628B2; DE19680835T1; NZ272892A; AU6891296A

Abstract

A mounting (11) to attach a chair back to a chair frame to allow for ergonomically acceptable support and movement. The mounting (11) has a support member (12) incorporated in each arm of the chair and attached to the chair frame, and torsion straps (14, 15) connected between the support member (12) and the chair back. The high tensile steel torsion straps (14, 15) are connected only at the position of connection (16, 17) with the support member (12) and chair back when a user applies a rearward force to the seat back, the back with resistance will move rearwardly and downwardly with a movement, which is ergonomically acceptable and comfortable for the user.

Description

IMPROVEMENTS IN/OR RELATING TO CHAIRS

This invention relates to chairs and in particular a mounting for a chair back.

BACKGROUND There is increasing recognition that ergonomic chairs are important for user comfort and health. An important aspect in such a design is the shape and movement of the back. In essence the chair back should work in harmony with the movement of the users back. Chairs with a rigid connection between the seat and back are not ergonomically satisfactory.

It is an object of the present invention to provide a mounting for a chair back which will allow for ergonomically acceptable support and movement of the chair back.

PRESENT INVENTION Accordingly in one aspect the invention consists in a mounting for a chair back, said mounting comprising support means adapted in use to form part of, or be attached to the chair frame at a position from which the chair back can be supported, and a torsion means connected between the support means and the chair back, said torsion means comprising high tensile metal strap means bent to an included angle of greater than a right angle operational when supporting the chair back to allow for a twisting or torsional action upon the supported chair back moving rearwardly upon a user leaning against the chair back with the movement also causing the chair back to lower towards the chair seat in a path that is ergonomically consistent with the seated body position.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

DRAWING DESCRIPTION

One preferred form of the invention will now be described with reference to the accompanying drawings in which:-

Figure 1 is a pictorial front view of one embodiment of a chair including a chair back mounting according to the present invention.

Figure 2 is a side view of Figure 1. Figure 3 is a rear view of Figure 1.

Figure 4 is a pictorial view of an alternative chair including a chair back mounting accordmg to the present invention.

Figure 5 is a yet further alternative chair including a chair back mounting according to the present invention.

Figure 6 is a top view ofthe chair back mounting according to the present invention.

Figure 7 is a side view of Figure 6.

Figure 8 is a bottom view ofthe chair back mounting.

Figure 9 is a pictorial top view of a chair arm incorporating the chair back mounting according to the present invention.

Figure 10 is an underneath view of Figure 9.

Chairs having a chair back mounting according to the present invention which have been ergonomically designed may be presented in a number of different configurations and an exemplary range only has been illustrated in the present invention.

PREFERRED EMBODIMENT In Figure 1 the chair 1 has a back 2 supported on arms 3 and 4 extending from the chair frame 5 which continues down to foπn the front leg 6 with the rear leg 7 extending from underneath and providing support for the seat 8. Arms 3 and 4 are attached to the chair back 2 with a space left between the points of connection with the back as is more clearly visible in Figure 3. While this is desirable for aesthetic reasons there is no structural reason why the mounting according to the present invention could not be formed to extend across the back ofthe chair.

As indicated above various chair configurations can be produced using the present invention and in Figure 4 a modified seat frame 9 is shown. In this chair the back 2b is similarly supported by the arms 3b and 4b as with the previous chair but with a different base support 9 as illustrated.

The chair lc as illustrated in Figure 5 is an executive style chair with a typical swivel base 10 supporting the seat 8c. The larger back 2c is supported on arms 3c and 4c again in a manner similar to that with the other chairs but with the arms extending down to attach to part ofthe frame supporting the seat 8c.

The various chairs have been illustrated to indicate that the present invention can be applied to a wide variety of chairs but will require a degree of modification in the way the mounting is attached to the chair frame but this will be clearly apparent to a person skilled in the manufacture of chairs. The mounting illustrated is particularly intended for chairs illustrated in Figures 1 to 4.

The mounting 11 according to the present invention will be incorporated in a chair arm adapted to be supported on the chair frame and connected to the chair back as previously indicated. The mounting 11 includes a support member 12 which is adapted in use to form part of or be attached to a chair arm and connected to the chair frame.

A preferred form of the mounting as illustrated in particular detail in Figures 6-8 has the support member 12 shaped and designed to be incorporated in a moulded polyurethane chair arm with a point of connection through the support member 12 to engage the chair frame.

The mounting 11 is completed by a torsion means 13 which is formed in the preferred embodiment by two rectangular high tensile steel straps 14 and 15. The straps are connected together at the positions of contact with the chair back and with the support means 12 but are otherwise unconnected between these points of contact. It has been found important to provide such a construction because the internal stresses within the torsional member are such that significantly increased life is achieved by adopting the two strap configuration. This is because the straps act independently and the internal stresses within the straps are within acceptable working tolerances ofthe material. 1065 high tensile spring steel may be used for the torsion straps. It would be possible to produce a configuration with more than two straps, but the increased cost is unlikely in most circumstances to be matched by any increase in efficiency.

Equally it would be possible to produce the torsion means as a single rectangular high tensile steel strap but at a cost of significantly reduced life expectancy. For this reason the invention is preferably provided with the two strap configuration.

The high tensile steel straps 14 and 15 are shaped to form an included angle of greater than right angles with the preferred range being between 105 and 120 degrees. Ergonomically acceptable movement of the chair back is possible with the point of contact of the mounting means and the chair back being at or adjacent to the lumbar region ofthe user, and the included angle being substantially 107 degrees.

The point of contact between the mounting means 11 and the chair back is through the high tensile steel straps 14 and 15 by attachment studs fitted through apertures 18 and

19 in the straps. The straps are attached to the support member 12 by bolts 16 and 17.

The angular configuration ofthe straps can be varied within reasonable ranges although it is desirable to preserve the configuration as described and illustrated if the desired ergonomic advantage is to be achieved. This is achieved because when a user applies force to the seat back causing a twisting action the back 2 will move about the mounting means. The connection between the mountings and the chair back is located at or towards the lumbar region ofthe user's back and the mounting provides a natural movement of the chair back for the user. Because of the angle at which the torsion straps are arranged the rearward movement also causes the back to move down towards the seat. This is a movement which is ergonomically acceptable and comfortable for the user.

The mounting has been tested through 200,000 cycles with a 400 newton force applied in the direction the seat backward movement in use. This testing did not result in any failure or noticeable deterioration in the mounting for the chair back.

As stated above the arm member 12 as illustrated is designed to be incorporated in a moulding which will form the armrest ofthe chair. The curved extension or tongue 20 is thus shaped to conform with the shape of the armrest and the apertures 21 are provided to give an increased bonding between the moulding and the arm support. A threaded stud 22 is provided as the support between the completed armrest including the mounting according to the present invention and the chair frame as illustrated in Figures 1 through to 4.

The completed arm rest 3 or 4 including the mounting is illustrated in Figure 9. The mounting studs 23 pass through the apertures 18 and 19 in the strap and the apertures 18a and 19a in the completed moulded arm rest and back mounting to engage in threaded sockets in the chair back. The under surface of the moulding has formed therein a slot 24 which accommodates the tubular frame ofthe chair with the stud 22 engaging through an aperture in the frame and with a nut locating the moulding in place.

One embodiment ofthe invention able to be incorporated in a chair arm moulding has been described but the chair design will influence the way in wliich the mounting is applied while preserving the concepts ofthe invention as set out above.

The advantage of the mounting is that the chair has the back supported to provide movement of the chair back ergonomically consistent with the seated body position.

Claims

1. A mounting for a chair back, said mounting comprising support means adapted in use to form part of, or be attached to the chair frame at a position from which the chair back can be supported, and a torsion means connected between the support means and the chair back, said torsion means comprising high tensile metal strap means bent to an included angle of greater than a right angle operational when supporting the chair back to allow for a twisting or torsional action upon the supported chair back moving rearwardly upon a user leaning against the chair back with the movement also causing the chair back to lower towards the chair seat in a path that is ergonomically consistent with the seated body position.

2. A mounting means as claimed in claim 1 wherein said support means is incorporated in or part of the chair arm, and is attached to and is supported from the chair frame, with mounting means provided in each chair arm providing support on each side of the chair back.

3. A mounting means as claimed in claim 2 wherein said torsion means extends from the support members to an attachment position on the chair back at or adjacent the lumbar region of the user when seated on the chair.

4. A mounting means as claimed in claim 3 wherein the torsion means is provided to extend across the chair back between support means provided in the chair arms.

5. A mounting means as claimed in any one of the preceding claims wherein the torsion means is made up of at least two high tensile steel straps connected together at the positions of contact with the chair back and the support means.

6. A mounting means as claimed in claim 5 wherein the torsion means comprises two parallel abutting high tensile metal straps each fixed at or towards one end to the support member, and at or towards the other end to the chair back being supported but with an independent operation under load between the points of connection.

7. A mounting means as claimed in any one ofthe preceding claims wherein the torsion means has an included angle of between 105 and 120 degrees.

8. A mounting means as claimed in claim 7 wherein the included angle is 107 degrees.

9. A chair having a back supported from the frame of the chair using mounting means according to any one ofthe preceding claims.