GB2107576A

GB2107576A - Adjustable seat back

Info

Publication number: GB2107576A
Application number: GB08221019A
Authority: GB
Inventors: Brian Barr Richardson
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-10-16
Filing date: 1982-07-19
Publication date: 1983-05-05

Abstract

A back support has a back support frame structure having guide rails 16 in its side members with a lumbar support pad 18 mounted on a female thread member 26 which in turn is mounted on a rotatable male threaded rod 28 which is integral with a flexible drive cable 30 having at its free end a knob 31. The height of the lumbar support pad 18 can be adjusted by turning the knob. Alternatively, the pad may carry a rack member engageable with a pinion or sprocket on a shaft. A similarly adjustable neck pad 25 may be provided. <IMAGE>

Description

SPECIFICATION Furniture construction This invention relates to furniture constructions, and particularly to a seat back construction for enabling the attainment of correct sitting posture.

As is in principle known, painful afflications can be caused by bad posture in sitting, and the adaption of such postures through laziness or bad design of furniture can lead to cartilage displacements such as "slipped discs" which can be extremely painful, often so painful as to be disabling. Other lesser afflications of strain and ill defined "back ache" are also caused by defective sitting posture.

Correct sitting posture involves maintaining the correct curvative of the spine particularly in the region loosley described as the small of the back where the spine should be slightly concave in curvature. A problem in furniture design has been the provision of pads of suitable configuration to provide the support required for this region of the back. This problem has now been largely solved with a number of proposals having been made as to the requisite shaping of support pads. However because of the fact that different persons are of differing statures and proportions, seats such as chairs must be specifically tailored to the individual user, or the support pad assembled in a position suitable for persons of average stature and proportions in bulk produced seats.These seats are however not completely satisfactory as the pads so not give the support required in the place required by persons of other than average stature and proportions.

An object of the invention is to provide a back support for a seat which enables a back support pad to be brought to the position required for support by any user, thus enabling any user to achieve correct support and correct sitting posture when sitting on the chair. Such correct support and posture will make an important contribution to the prevention and/or alleviation of clinical and sub clinical back disorders ranging from displaced cartilages to discomfort.

According to the invention a back support for a seat comprises a back support frame structure, a lumbar support pad, and means for raising and lowering such pad relative to the support frame structure.

The lumbar support pad is intended to rest in and support the concave curvature of the spine in the small of the seat user's back. This pad preferably is generally convex with its convex surface directed towards the user. The support pad is preferably mounted on guide rails in the support structure so as to be freely moveable up and down.

The pad may be mounted on a female threaded member, in turn mounted on a rotatable male threaded rod. The rod is preferably rotationally integral with a reversible flexible drive cable having a manipulation knob at its free end. The flexible cable enables the knob to be manipulated by a person sitting on a chair of which the back support forms part and adjusts the height of the lumbar support pad by rotating the knob and thus the rod, with consequent displacement of the pad via the female threaded member.

Alternatively, a rack member, similar for example to a length of bicycle chain, or an array of pins or teeth mounted on the pad, and a sprocket or pinion mounted in the frame and arranged to engage in the rack member and be rotated by a knob or handle for displacement of the pad.

A similar additional moveable support pad may be provided near the top of the back support structure to act as a neck support.

This also may be moveable by a screw and cooperating nut member actuated by a second flexible drive or by a rack and pinion device as outlined above.

The neck pad may be of any required foamed material, whilse the lumbar support pad is advantageously provided with a shaped core of higher density foam covered with a membrane in the form of a polythene sheet treated with a silicone material to reduce friction between the pad and a covering of the back support of medium density foam which faces the back support.

Preferred embodiments of the invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a perspective view, showing a chair having a back support according to the invention with a first form of actuating device, Figure 2 is a sectional view showing the arrangement of a lumbar support pad in the back support in the Fig. 1 embodiment, together with its actuating device, and Figures 3 and 4 are similar views of a second embodiment of chair according to the invention.

As illustrated in the drawings, in accordance with a preferred embodiment of the invention, a chair 10 has a back support 11. This support is shown without upholstery, padding, and finishing cover so that the interior construction of the back support 11 can be seen.

The back support 11 has a frame comprising side members 12, 1 3 and cross struts 14, 14 secured by timber joints, or dowelling or screws usual in the furniture construction art.

The side members each have a lower longitudinally extending slot such as 16, which guide spigot members such as 1 7 carried on a lumbar support pad structure 1 8. Each side member 12, 1 3 also has an upper longitudinally extending slot such as 19, receiving guide spigots such as 20 on a neck support structure 21.

The lumbar support pad structure comprises a base board 22 (see Fig. 2) and a higher density foam pad 23 formed with a convex surface 24, with a cross section which approximates to a half-teardrop shape or exagerated aerofoil with the thickest part of the pad towards the lower edge.

The neck support structure 21 is similar having a high density foam pad 25 on a board (not shown) on convex shape.

The board 22 of lumbar support structure 1 8 carries a member 26 having a female threaded bore 27 and thus constitutes a nut member received on a male threaded rod 28 which extends upwardly within the back support frame and below or behind the structure 1 8. The screw thread on the rod 28 is a multi start thread. Rod 28 is connected at its lower end by a coupling 29 to a flexible drive cable 30 which extends to a handle or knob 31 which can be easily reached by a person seated on the chair. The coupling 29 is fixed to the frame e.g. to cross member 14 in such a way that axial displacement of the rod 28 is prevented. Thus when the flexible drive 30 is rotated in a first sense, e.g. clockwise, consequent rotation, of rod 28 raises member 26 elevating the lumbar support pad 18, 23.

Rotating the drive 30 in the opposite sense counter clockwise the member 26 and lumbar support pad 18, 23 descend the spigots 1 7 sliding in slot 1 6 in the back support structure side frame members.

The neck support pad 21, 25 is provided with a similar mechanism for adjustment of its height, with guide spigots 20 sliding in slots 19, the respective threaded rod and counter threaded nut member not being shown in the drawings but being similar to the rod 28 and member 26 of the lumbar support pad structure 1 8. The neck support pad operation is worked by a knob 33 on a flexible drive cable 32 which is connected to the neck support pad rod by a coupling similar to 29, which is also fixed relative to the back support structure frame, e.g. on cross member 1 5.

The back support structure is covered with a layer of normal denisty foam; of the kind ordinarily used in upholstery, extending the height of the back support structure 11, and covering the lumbar support pad 23 and the neck support pad 25. A film or sheet 35 of polythene is laid between the foam layer 34 and the pads 23, 25 and this sheet 35 has a silicone anti-friction coating on the surface directed towards the pads 23, 25. By this expedient friction, which would otherwise occur between pads 23, 25 and foam layer 34, probably leading to jamming and possibly to damage of the foam because of the high coeffieient of friction existing between the two foam pads, is virtually eliminated, so that the pads 23, 25 may be freely adjusted for position below the layer 34 as required.

Referring to Fig. 3 and 4, the second embodiment of chair according to the invention is generally similar to that of Figs. 1 and 2. However, the actuation mechanism comprises a rack member 41, similar to a length of bicycle chain secured to the board 22, and a sprocket or pinion 42 mounted on a shaft 43 journalled in the side frames 1 2, 1 3 and operable by a knob 44. The neck pad 25 is provided with a similar rack and pinion apparatus, operable by a knob 45.

The back support structure described is applicable to all forms of seating, including private seating forming home funishings, public seating in restaurants, auditoria and waiting rooms and in vehicles such as private cars and public vehicles. A muiti seat couch or settee or multiple seat in a train or aircraft for example may have a separate such back support for each person to be accommodated.

The back support is infinitely adjustable within the overall limits of travel of the pads.

The neck support is an optional but desirable extra. A Single standard design of back support may be marketed to meet the requirements of all sustomers or users within a normal range of stature and proportions. It is not necessary for a back support to be custom built for each prospective user as the movable lumbar support pad, and neck support pad if present, can be adjusted to be suitable for any user within a wide range of statures and proportions. A chair thus equipped can according be occupied in quick succession by people of different statures who can each adjust the positions of the pads to the locations required for their own comfort and proper sitting posture.

Claims

1. A back support for a seat comprising a back support frame structure, a lumbar support pad, and means for raising and lowering the pad relative to the support frame structure.

2. A back support for a seat as claimed in claim 1 wherein the lumbar support pad is constructed with a convex surface directed towards the user's back when seated.

3. A back support for a seat as claimed in claims 1 or 2 wherein the support pad is mounted on guide rails in the support structure and is freely movable thereon.

4. A back support for a seat an claimed in claim 3 and wherein the pad is mounted on a female threaded member which is in turn mounted on a rotatable male threaded rod.

5. A back support for a seat as claimed in claim 4 wherein the rotatable male threaded rod is rotationally integral with a reversible flexible drive cable having a manipulation knob at its free end which by turning raises and lowers the support pad within the back support frame structure.

6. A back support for a seat according to claim 1 or 2 wherein the means for raising and lowering the pad comprises a rack member mounted on the pad and a pinion on a shaft rotatably mounted in the support frame and having a handle for operation.

7. A back support for a seat as claimed in any of claim 1-6 wherein an additional movable support pad may be provided at the top region of the back support structure or act as a neck support.

8. A back support for a seat as claimed in anyone of claims 2 to 7 wherein the lumbar support pad has a shaped core of high density foam.

9. A back support for a seat as claimed in claim 8 wherein the high density shaped core of the support pad is covered with a membrane in the form of a polythene sheet treated with a silicon material to reduce friction between the pad and a covering of the back support of lower density foam.

10. A back support for a seat substantially as hereinbefore described with reference to and as illustrated in Fig. 1 and 2 or Figs. 3 and 4 of the drawings annexed.