WO1994010877A1

WO1994010877A1 - Ergonomic chair

Info

Publication number: WO1994010877A1
Application number: PCT/GB1993/002246
Authority: WO
Inventors: Engin Turker
Original assignee: Loughborough University Of Technology
Priority date: 1992-11-06
Filing date: 1993-11-01
Publication date: 1994-05-26
Also published as: AU5374894A; GB9223296D0

Abstract

There is disclosed a chair comprising a seat and a backrest lumbar support relatively adjustable in height.

Description

- 1 -

ERGONOM1CCHAIR

This invention relates to chair design.

It is estimated that office workers, particularly those using computer or word processor workstations, spend 8% of their lives sitting performing their work. Commercial drivers, train drivers and pilots spend long periods on a daily or almost daily basis confined to - most often, in fact, strapped into - a seat.

Considerable attention has been given over many years to sitting posture and to the design of chairs, and many resulting improvements have been incorporated into so-called ergonomic designs. The subject is important - increase in musculo-skeletal problems has been linked to the long periods office workers spend seated, and tens of millions of working days are lost annually in Great Britain as a result of back problems.

The present invention provides improved seating, especially for the work-place (including drivers' and pilots' seating) that can alleviate some at least of the problems experienced. - 2

The invention in one aspect comprises a chair comprising a seat and a backrest lumbar support relatively adjustable in height.

The lumbar support may be adjustable for height relative to the seat within a fixed-height backrest. The lumbar support may comprise a bolster which is elevatable within the backrest structure. The backrest structure may comprise a pinion and the bolster a rack. The lumbar support may protrude 25-35 mm from the front of the backrest.

The entire backrest, on the other hand, including lumbar support may be adjustable for height relative to the seat.

The seat may be adjustable for inclination; the backrest may be adustable for inclination; and the seat may be adjustable for height.

The chair may have armrests, which may be adjustable for height relatively to the seat.

The invention, in another aspect, comprises a chair having pressure sensing means and sensed pressure analysing means having a posture-corrective output. - 3 -

The posture-corrective output may comprise an audible signal indicating poor posture. The posture- corrective output may comprise an audible signal indicating the adoption of a good posture on a change of posture.

The posture-corrective output may comprise automatic adjustment of an adjustable part or adjustable parts of the chair.

The pressure sensing means may sense seat pressure and backrest pressure. The pressure analysing means may compute ratios between backrest and seat pressures and compare them with preset ratios. The preset ratios may depend upon the adjustment of an adjustable part or adjustable parts of the seat.

The• chair may have powered seat height adjustment.

The chair may have a data arrangement automatically adjusting the chair to an identified occupant. The chair may have a reader for adjustment data pertinent to an individual occupant, and automatic adjustment means effecting automatic adjustment according to said adjustment data. Said reader may be a smart card reader. Said data arrangement may, however, - 4 -

comprise a chair-borne memory having storage for sets of adjustment data addressable via an identification code and on entering said code adapted to adjust the chair in accordance with the appropriate data.

The chair may be used in conjunction with a personal data coding arrangement to give a code derived from a set of personal data and an input arrangement for said code adapted to effect automatic adjustment of the chair in accordance with said set of personal data.

The chair, when provided with automatic adjustment means, may be provided with an override arrangement.

The invention also comprises a workplace seating arrangement including a plurality of chairs each according to the invention as above described, and this may be together with a set of personal tokens inter¬ active with the chairs to adapt the chairs to personnel occupying them for the time being.

Embodiments of chairs according to the invention will now be described with reference to the accompanying drawings, in which :-

Figure 1 is a part-sectional side elevation of one embodiment; - 5

Figure 2 is a front elevation of a lumbar support suitable for use in the embodiment of Figure 1;

Figure 3 is a section on the line III-III of Figure 2;

Figure 4 is a side elevation of another embodiment;

and Figure 5 is a block diagram of a pressure- sensing, posture-corrective arrange¬ ment.

Figures 1 to 4 illustrate chairs, in particular chairs suitable for office workers, especially those who operate keyboards of computer or word processor workstations. The chairs comprise a seat 11 and a backrest lumbar support 12 relatively adjustable in height.

Figures 1 to 3 illustrate a chair in which the lumbar support 12 is adjustable for height relative to the seat 11 within a fixed-height backrest 13 - by fixed-height in this connection is meant fixed-height relative to the seat, it not being excluded that the seat and backrest are together elevatable on the pedestal support 14 in known or equivalent manner. - 6 -

The lumbar support 12 comprises a bolster which is elevatable within the backrest 13 structure. The backrest structure comprises a pinion and the bolster 13 a rack 16, as more clearly seen in Figures 2 and 3. The backrest 13 structure comprises side members on which the bolster 13 runs in bearings 13a and which support a shaft 17 carrying the pinion 15. The shaft 17 extends beyond the width of the backrest 13 carrying adjusting knobs 18. The bolster 12 comprises a moulded member with overlying padding 19. It is contained beneath an outer flexible upholstery 21 which is capable of bulging to accommodate the bolster 12. Between the backrest upholstery 21 and the bolster 12 is a resilient, e.g. tensioned, rubber band arrangement 22.

The lumbar support bolster 12 protrudes some 25-35 mm from the front of the backrest 12.

Figure 4 illustrates an embodiment in which the entire backrest 13 including the lumbar support 12 is adjustable for height relative to the seat 11. The backrest 13 is carried on a column arrangement 23 which is telescoped in a sheath in the seat and fixable at chosen height by a clamping arrangement (not shown) in any convenient way. In both embodiments, the seat 11 is adjustable for inclination. In the embodiment of Figures 1 to 3, the seat 11 is mounted on a platform 24 atop the pedestal 14, the seat 11 having a transverse shaft 25 borne in a journal bearing in the platform 24 and securable at any desired tilt angle by clamp means (not shown) of any desired type. It can be arranged that the seat can be adjusted for tilt through an angle of say 10° or 20°, different tilt orientations being suitable for different types of work operation, e.g. writing and keyboard operation.

In the embodiment of Figure 4, the seat 11 is on an arcuate bearing arrangement 41 on the platform 24, movement on the bearing arrangement 41 being controlled e.g. frictionally, to allow for an occasional change of posture by leaning back. Such an arrangement can avoid fatigue problems due to prolonged sitting in a single position.

In the embodiment of Figures 1 to 3, the backrest 13 is adjustable for inclination relative to the seat 11, being mounted on a clampable bearing 31 at the back of the seat 11. In the embodiment of Figure 4, the inclination of the backrest 13 relative to the seat 11 is not independent of the height adjustment of the backrest 11 - as the backrest 11 is raised it is tilted forwardly. - 8 -

The seat 11 in both embodiments is adjustable for height for example by the pedestal 25 having an upper part threaded into a lower part or being on a gas strut arrangement.

The chair may have armrests, which may be fixed to the seat 11 but which are preferably adjustable in height relative thereto. Suitable arrangements are known and need not be described nor illustrated here. However, arrangements which couple the height adjustment of armrests with the adjustment of the lumbar support, for example, armrests fixed to the backrest 13 of the chair illustrated in Figure 4, may have particular interest in connection with the invention.

The embodiments of Figures 1 to 4 provide adjustability not only to accommodate different sizes of user but also to adapt the chairs to different tasks performed by the same user. As noted, keyboard operations call for a different posture to writing. However, even though the chair may be optimally adjusted for the user and for the task the user is performing, the user may still adopt an unsuitable posture.

Figure 5 illustrates the provision of pressure sensing means 51 and sensed pressure analysing means 52 having a posture-corrective output. The pressure sensing means 51 comprise flat pressure sensing pads located two beneath the seat cover and two in the backrest. Criteria can be established for optimal ratios between backrest and seat pressures on the basis of posture studies. Where the backrest is in use, i.e. when the user is not sitting forward clear of the backrest, criteria can be established for optimal ratios between pressure on the lumbar support and elsewhere on the backrest. Likewise, the ratio between pressures forward and rearward of the seat can be used as an indicator of good sitting posture.

The analog output from the flat pad pressure transducers 51 is converted to digital in A/D converters 52 and the digital signals input to a microprocessor 53 for computation of ratios and comparison with ratios held in ROM 54. Comparison ratios can be tabulated according to seat/backrest tilt values which can be input to the microprocessor 53 from appropriate transducers.

In one arrangement, actual pressure ratios falling outside preset limits from any of the comparison ratios can trigger an alarm buzzer 55, requiring posture correction to silence it. Delays can be built in to avoid a momentary incorrect posture or a shift in position setting off the alarm buzzer. In addition, a timer can be set to sound the buzzer if any posture has been held for too long.

The adoption e.g. on change of posture of an acceptable, i.e. within limits, posture could also trigger the buzzer 55 to emit a friendly "approving" tone.

The various adjustments, or at least one of them, principally the lumbar support height, can be motorised, the microprocessor instructing e.g. a stepper motor to make the adjustment towards an acceptable ratio.

While such electronic arrangements seem somewhat sophisticated for the humble typist's chair, it has to be recognized that the component cost is small by comparison with the cost of a chair of reasonable quality. Automobiles already have motorized adjustment of seat variables and these can be memory driven auto¬ matically to adjust between drivers.

In addition to the above measures, and as already practised in automobile seating, the chair may have powered seat height adjustment. The chair may have a data arrangement, where it is likely to be occupied by several people at different times, automatically adjusting it to an identified occupant. The chair may for instance have a micro¬ processor controlling its adjustment, and a set of people who will from time to time occupy the chair can copy, for example, a smart card which is read by a smart card reader associated with, e.g. incorporated in the chair. The smart card can carry the values of each of the chair variables appropriate to or preferred by the individual.

However, the chair may have a chair-borne memory having storage for sets of adjustment data as pertinent to an individual occupant. The adjustment data may for example include not only lumbar support adjustment but also seat height, backrest height, armrest height and so forth, and. such sets of data may be held in memory accessible by codes. In the armrest there could be a keypad e.g. a numeric keypad on which a two digit code could be entered to access the appropriate set of data. Each user would have his or her own access code and enter it via the keypad on first using the chair, which would then automatically adjust to the configuration specified by the data. In another arrangement, the code may not need to be personal inasmuch as more than one person can be accommodated by a given set of data. From a graph or table of population data, a code can be derived by reference to the appropriate values of variables such, again, as height, weight and so on. Then each chair can hold the same information.

Any automatically adjusted chair can, of course, be provided with override means, or simply an on/off button.

For a workplace such as an office or a factory where people circulate between desks and chairs., all the chairs may be adjustable according to the invention, and the personnel provided with tokens (e.g. smart cards or transmitters or transponders) which are used or which react when the chair is. occupied to make the appropriate adjustment.

Chairs may be provided with individual battery power supplies or may be plugged in to a mains supply of power.

As mentioned, the invention has relevance beyond the field of chairs for office and other sedentary workers; drivers of public service and road haulage vehicles, train drivers and aircraft pilots would benefit, as might also, in fact, airline passengers, especially on long-haul flights; at least the height- adjustable lumbar support could be provided at no very great cost or weight penalty.

Claims

1. A chair comprising a seat and a backrest lumbar support relatively adjustable in height.

2. A chair according to claim 1, in which the lumbar support is adjustable for height relative to the seat within a fixed height backrest.

3. A chair according to claim 2, in which the lumbar support comprises a bolster which is elevatable within the backrest structure.

4. A chair according to claim 3, in which the backrest structure comprises a pinion and the bolster a rack.

5. A chair according to any one of claims 2 to 4, in which the lumbar support protrudes 25-35 mm from the front of the backrest.

6. A chair according to claim 1, in which the entire backrest including lumbar support is adjustable for height relative to the seat.

7. A chair according to any one of claims 1 to 6, of which the seat is adjustable for inclination.

8. A chair according to any one of claims 1 to 7, of which the backrest is adjustable for inclination.

9. A chair according to any one of claims 1 to 8, of which the seat is adjustable for height.

10. A chair according to any one of claims 1 to 9, having armrests.

11. A chair according to claim 10, of which the armrests are adjustable for height relatively to the seat.

12. A chair having pressure sensing means and sensed pressure analysing means having a posture-corrective output.

13. A ghair according to claim 12, said posture- corrective output comprising an audible signal indicating poor posture.

14. A chair according to claim 12 or claim 13, said posture-correcting output comprising an audible signal indicating the adoption of a good posture or a change of posture.

15. A chair according to any one of claims 12 to 14, in which said posture corrective action comprises automatic adjustment of an adjustable part or adjustable parts of the chair.

16. A chair according to any one of claims 12 to 15, in which the pressure sensing means sense seat pressure and backrest pressure.

17. A chair according to claim 16, in which the pressure analysing means compute ratios between backrest and seat pressures and compare them with preset ratios.

18. A chair according to claim 17, in which the preset ratios depend upon the adjustment of an adjustable part or adjustable parts of the seat.

19. A chair according to any one of claims 1 to 17, having powered seat height adjustment.

20. A chair according to any one of claims 1 to 17, having a data arrangement automatically adjusting the chair to an identified occupant.

21. A chair according to claim 20, having a reader for adjustment data pertinent to an individual occupant, and automatic adjustment means effecting automatic adjustment according to said adjustment data.

22. A chair according to claim 21, said reader being a smart card reader.

23. A chair according to claim 20, said data arrangement comprising a chair-borne memory having storage for sets of adjustment data addressable via an identification code and on entering said code adapted to adjust the chair in accordance with the appropriate data.

24. A chair according to claim 20, in conjunction with a personal data coding arrangement to give a code derived from a set of personal data, and an input arrangement for said code adapted to effect automatic adjustment of the chair in accordance with said set of personal data.

25. A chair according to any one of claims 1 to 24, having automatic adjustment means provided with an override arrangement.

26. A workplace seating arrangement including a plurality of chairs each according to any one of claims 1 to 25.

27. A workplace seating arrangement according to claim 26, together with a set of personal tokens interactive with the chairs to adapt, the chairs to the personnel occupying them for the time being.