AU665208B2

AU665208B2 - Weight compensating chair backrest

Info

Publication number: AU665208B2
Application number: AU24219/92A
Authority: AU
Inventors: Peter James Riddle
Original assignee: Duffield Anne Constance
Current assignee: Duffield Anne Constance
Priority date: 1991-08-22
Filing date: 1992-08-04
Publication date: 1995-12-21
Anticipated expiration: 2012-08-04
Also published as: AU2421992A; WO1993003653A1

Description

2i-a, OPI DATE 16/03/93 APPLN. ID 24219/92 III I lII III 111NllIII AOJP DATE 27/05/93 PCT NUMBER PCT/AU92/00404 III AU9224219

-(PCT)

(51) International Patent Classification 5 11) International Publication Number: WO 93/03653 A47C 7/44, 1/032, 1/024 Al (43) International Publication Date: 4 March 1993 (04.03.93) (21) International Application Number: PCT/AU92/00404 Published With international search report.

(22) International Filing Date: 4 August 1992 (04.08.92) Priority data: PK7897 22 August 1991 (22.08.91) AU (71)(72) Applicant and Inventor: RIDDLE, Peter, James [AU/ AU]; 190 Rathmines Road, Hawthorn East, VIC 3123

(AU).

(81) Designated States: AT, AU, CA, DE, DK, FI, GB, JP, KP, KR, NO, RU, SE, US, European patent (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, MC, NL, SE).

(54)Title: WEIGHT COMPENSATING CHAIR BACKREST 7 1 8

J

(57) Abstract Improvement to chairs whereby the chair back is moveable and the support given to the back of the user is by means of a lever system 10) and rubber or other elastomeric torque resisting device connecting seat and back and apportioning part of the user's body weight to their back support.

i c~ WO 93/03653 PCT/AU92/00404 -1- Weight Compensating Chair Backrest This invention relates to improvements to moveable back chairs.

Most people find it arduous to sit for long periods in a chair with a rigid back,and many efforts have been made in the past to design a chair with a moveable back having sufficient support for the back of the occupant.

Most of these designs have relied on some sort of spring device to achieve this aim,but metal springs being of constant and linear resistance according to Hooke's law and having deflection directly proportional to applied load, give the lighter user too much resistance or the heavier user too little supsupport without having to resort to some sort of manually operated device to compensate for varying users weights.

This problem is overcome with the present invention by the use of rubber or some other elastomeric device, such substance having resisting qualities of non-linear character so as to provide the necessary increase in resistance for heavier occupants and, conversely,lesser resistance for the lighter user.

In one form, the chair consists of a base,a seat lever to which is attached the seat.Said seat lever being hinged to the forward part of the base.The back lever is also hinged to the base,but at towards the rear of the base.Hinged also to the base and hav- Sing an axis common to the back lever is an interconnecting lever connected at it's forward end to the rearward end of the seat lever by a hinged joint.

i. i- I WO 93/03653 PCT/AU92/00404 Both the interconnecting lever and the back lever are free to rotate about their common axis, but have interposed between them and preferably arranged radially a rubber or other elastomeric device to provide the previously mentioned resistance between the two levers.

There are other restricting devices to the said levers consisting,in the case of the back lever,of a stop on the base preventing the back lever from moving forward more than the upright position,and another stop on the base preventing the the back from moving backwards further than a pre-determined position,regardless of the weight of the occupant.

The restraints on the seat lever consist of a locking joint similar to a human knee joint preventing the seat leverfrom moving upwards further than a pre-determined and designed position.Downward movement of the seat lever is restricted by the interconnecting lever and it's dependence on the chair's back stop.

The chair may be more fully described by reference to figure 1 on page 1 of the attached drawings showing the general arrangement of the various parts mentioned in the foregoing.

The base l,in this instance,consists of a metal channel to which is affixed the column base 9,or which base could be attached to the conventional four legs or any other suitable support.

The back lever and interconnecting lever axis is as shown by 4 in the diagram in the same drawing and the seat lever hinge as 5,also in the same drawing.

A further hinge joint 6,is shown at the forward end of the base,and this connects,by a toggle lever to hinge 5 with the sole purpose of correcting the length disparity of the system owing to the opposing radii of the interconnecting lever and the seat lever.

I

Ma WO 93/03653 PCT/AU92/00404 -3- Referring now to figure 2 on page 1 of the attached drawings,it can be seen that the outer part of the Torque resisting device 12,is attached to the back lever 3, and these two parts act as one entity.The central part of the torque resisting device 11.is attached to the interconnecting lever 10,and these two parts also act as an entity.

It is not important which of these two entities occupies the inner or outer position,the result is the same,and depends only on the convenience of manufac ure.

The rubber or elastomeric device 14, is shown arranged radially between these two entities.The back lever stops are shown as 1, the rear of the base frame in this case and 15, and are respectively, the forward stop and the rearward stop for the back lever.

The seat lever is shown as 2, in the drawing,and in this instance is also a metal channel fitting within the base channel.

Referring now to page 2 of the attached drawings it will be made clear how the mechanism operates.

Diagramatically, figure 3 shows the interconnecting lever 10, shown by the dashed lines as is the underside of the seat lever in that position.Shown also in the same figure depicted by solid lines, are the levers in the losaded position after the user has occupied the chair, but has not put any weight on the back of the chair.

Figure 4 shows the levers in the original position where,the user having started to lean back in the ;chair,and the torque resisting device is locked into S100. a solid state for that user the occupant will be supporting his back by leverage alone.On leaning back further the user will encounter the resistance of the energy stored in the torque resisting device providing further support as is necessary.

L l-i-L. r L

Claims

1. A chair wherein the occupant is given freedom of back movement with suitable support to the users back by trans- ferring part of the users weight on the seat to the chair back on his leaning back,as a resistance and support, and on such a chair there is a rigid base such base having hinged at the forward end the seat lever holding the seat and at the rear end of the base is hinged the back lever holding the backrest and on this hinge also with an axis common to the back lever but free to move independently of the back lever ,is an interconnecting lever projecting forwards,parallel to and between the seat lever and the base pinned at its forward end to the rearward end of the seat lever and such interconnecting lever having at its rear end a transverse square shaft through which the rear axis pin passes, and around this square shaft is a rubber or other elastomeric component which is contained on its outer perimeter by a square tube rigidly attached to the lower end of the back lever,and such arrangement is ter- med the torque resisting device. S, 2. A chair as in claim 1. having a torque resisting dev- ice of non-linear characteristicsas outlined above such 'that a heavier user will encounter progressively greater resistance to the downward movement than a lighter user I 25. on initial occupancy and also both users will experience progressively greater resistance of the backrest in an increasingly reclined position.

3. A chair as in claims 1. and 2. wherein the users weight will depress the seat against the torque resisting dev- ice through the interconnecting lever a distance propor- i tional to the users weight thereby storing energy in the torque resisting device, as the back lever is prevent- ed from moving forward by means of a stop attached to the base.

4. A chair as in claims 1, 2.and 3. whereby the user, on Sleaning back encounters resistance and support proport- 0 t- ional to the users weight and the energy stored in the L proportional to the users weight and the energy stored in the torque resisting device. A chair as in claims 1.2.3.and 4.wherein the user,on leaning back further than claim 4 will cause the inter- connecting lever to move upwards,due to the torque res- isting device having locked into a solid state for that particular user so that the part of the interconnecting lever forward of the seat lever and interconnecting lever hinge pin encounters the seat lever locking the mechanism in the manner of the human knee, and further resistance will be solely through the energy stored in the torque resisting device.

6. A chair as in claims 1.2.3.4.and 5 wherein the ratio of lengths of the interconnecting lever to the seat lever will be between 1 to 2.3 and 1 to 3.5 dependent on the resistance built into the torque resisting device.

7. A chair as in claims 1.2.3.4.5.and 6. whereby the chair will be suitable for occupants of varying weights,

55. each occupant receiving appropriate back support pro- portional to their body weight as in claim without hav- ing to manipulate various controls to achieve the correct support. 8. A chair as in claims 1.2.3.4.5.6.and 7. constructed of steel channels as shown in the accompanying drawings 1 or other materials or sections which may be suitable. 9. A chair as in claims 1.2.3.4.5.6.7.and 8 with moveable and interacting seat and back substantially as herein described with reference to the accompanying drawings. go i _i