Pennington, Mark Rundle (Wellington, NZ)
Fifield, Jon Leonard (Wellington, NZ)
Stewart, Robert Bruce (Lower Hutt, NZ)

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11/390956

10/28/2008

03/28/2006

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Formway Furniture Limited (Wellington, NZ)

297/320

297/316, 297/319

A47C1/024

297/320, 297/337, 297/316, 297/319

0226082		March, 1880	Lemman
0272579		February, 1883	Paulding
0323060		July, 1885	Moore
0614235		November, 1898	Palmer
0662247		November, 1900	Vinton
0662647		November, 1900	Howe
0799128		September, 1905	Wilmot et al.
1120686		December, 1914	Burrowes
1976793	Air-tight closed hollow body	October, 1934	Mangold
2071974	Chair back	February, 1937	Gunlocke
2083838	Chair	June, 1937	Goenen
2365200	Adjustable chair	December, 1944	Lorenz
2471024	Chair with tilting back and automatically shiftable seat	May, 1949	Cramer
2590995	Woven fabric adapted for use as upholstery covers and the like	April, 1952	Merrill
2612211	Removable cushion plate and seat standard	September, 1952	Gielow et al.
2796918	Article of repose for supporting the body of a person	June, 1957	Luckhardt
2804129	Cushion construction	August, 1957	Propst
2833339	Seat construction	May, 1958	Liljengren
2845997	Foamed plastic seat and the like	August, 1958	Waite
2858572	Method of making advertising signs	November, 1958	Burdick
2887692	Inflatable cushion or the like	May, 1959	Gosman
2962764	Process for the manufacture of molded articles	December, 1960	Trojanowski et al.
3009578	Pre-stressed reinforced ion-exchange membrane and method of making same	November, 1961	Foote et al.
3015148	Spacer fabrics and method of making them	January, 1962	Haddad
3030640	Inflated articles	April, 1962	Gosman
3041109	Web and spreader furniture construction	June, 1962	Eames et al.
3107991	Screen	October, 1963	Taussig
3112987	Production of cushioned seats	December, 1963	Griffiths et al.
3115678	Apparatus for molding plastic carpets	December, 1963	Keen et al.
3124092		March, 1964	Raynes
3139305	Reclining chair and fixture	June, 1964	Mizelle
3165359	Woven support for furniture	January, 1965	Ashkouti
3208085	Resilient cushion	September, 1965	Grimshaw
3214314	Method for screen assembly	October, 1965	Rowbottam
3222698	Resilient plastic seat elements	December, 1965	Levenson
3273877	Seat structure	September, 1966	Geller et al.
3298749	Arrangement for storing wood chips	January, 1967	Albinson et al.
3301931	Method of making looped snells	January, 1967	Morin
3314721	Chair construction	April, 1967	Smith
3319274	Mattress with sag-resistant insert	May, 1967	Upton
3337267	Positionable chair	August, 1967	Rogers, Jr.
3399883	Seat construction	September, 1968	McKey
3399926	Furniture construction	September, 1968	Hehn
3431022	CHAIR CONSTRUCTION	March, 1969	Poppe et al.
3434181	APPARATUS FOR TENSIONING SHEET MATERIALS	March, 1969	Benzies
3534129	SEAT CONSTRUCTION AND THE LIKE	October, 1970	Bartel
3546724	MATTRESSES	December, 1970	Bastos et al.
3589967		June, 1971	Shirakawa
3620568	AIRCRAFT CREWSEAT	November, 1971	Morrow
3652126	PNEUMATIC ADJUSTMENT SYSTEM FOR SEAT BACK PANEL	March, 1972	Folling
3712666	CHAIR	January, 1973	Stoll
3740792	RESILIENT HINGING DEVICE FOR CHAIRS AND THE LIKE	June, 1973	Werner
3770235	RESILIENTLY SUPPORTED SEAT	November, 1973	Klapproth et al.
3826456	ROCKING CHAIRS	July, 1974	Tranter et al.
3869172	CHAIR RECLINING MECHANISM	March, 1975	James et al.	297/316
3937518	Recliner lounger T-cushion chair with projectible headrest and legrest, and hardware therefor	February, 1976	Harrison
3942835	Recliner rester chair with projectible legrest and headrest, and hardware therefor	March, 1976	Harrison
3950026	Chair or a wheeled chair	April, 1976	Van Seenus
3974532	Padding for mattresses and like articles	August, 1976	Ecchuya
4017118	Patient supporting device	April, 1977	Cawley
4025113	Linkage mechanism for handle operated recliner chair	May, 1977	Rogers, Jr.
4040661	Vehicle seat with headrest movement responsive to seat back tilting	August, 1977	Hogan et al.
4043592	Adjustable seat back mechanism	August, 1977	Fries
4054317	Chair construction	October, 1977	Stumpf
4122568	Mattress of the hard surface type	October, 1978	Bastos et al.
4123104	Headrest for a motor vehicle	October, 1978	Andres et al.
4143910	Chair having synchronously coupled tiltable seat and back rest	March, 1979	Geffers et al.
4145020	Retractable apparatus for supporting an element	March, 1979	Webster
4154478	Portable headrest	May, 1979	Cohune
4158899	Seat	June, 1979	Budimirov
4159148	Folding arm rest accessory	June, 1979	Schulz
4191422	Adjustable headrest	March, 1980	Inasawa et al.
4202581	Support means for portable furniture	May, 1980	Fleishman
4205878	Pull out headrest	June, 1980	Wooten
4265482	Head-rest adjusting device	May, 1981	Nishimura et al.
4285545	Automobile passenger seat with an automatically positioned headrest	August, 1981	Protze
4345733	Mounting device for a chair seat	August, 1982	Ambasz et al.
4353595	Headrest control device for a treatment chair	October, 1982	Kaneko et al.
4380352	Reclining chair	April, 1983	Diffrient
4390204	Portable furniture	June, 1983	Fleishman
4390206	Synchrotilt chair control	June, 1983	Faiks et al.
4406496	Backrest for chairs	September, 1983	Drabert et al.
4408797	Furniture article with padding attached to a supporting shell	October, 1983	Franck et al.
4411469	Chair, particularly a data display chair	October, 1983	Drabert et al.
4415203	Dental chair	November, 1983	Cawley
4418958	Plastics chair shell	December, 1983	Watkin
4429917	Chair	February, 1984	Diffrient
4451081	Headrest for a reclining chair	May, 1984	Kowalski
4466662	Powered articulated headrest system	August, 1984	McDonald et al.
4479679	Body weight chair control	October, 1984	Fries et al.
4491364	Lumber support system for a vehicle seat	January, 1985	Hattori et al.
4496190	Parallel folding armrest	January, 1985	Barley
4498702	Seating unit with front flex area	February, 1985	Raftery
4502731	Seat frame	March, 1985	Snider
4509793	Chair	April, 1985	Wiesmann et al.
4515406	Headrest for medical treatment chair	May, 1985	Fujiyama et al.
D279635	Support unit for adjusting a chair seat depth	July, 1985	Aasen
4533174	Portable furniture	August, 1985	Fleishman
4534593	Vehicle seat lumbar support insert and method of utilizing the same	August, 1985	Ojala
4540217	Headrest device for a vehicle seat	September, 1985	Suzuki
4552406	Chair	November, 1985	Ohi
4555136	Furniture construction	November, 1985	Dranger
4560199	Recliner chair	December, 1985	Sapper
4570994	Foldable chair	February, 1986	Lowrey
4580837	Vehicle seat	April, 1986	Bayley
4585272	Chair having a back comprising a plurality of articulated segments	April, 1986	Ballarini
4596421	Office chair	June, 1986	Schmitz
4603830	Spring mounting apparatus	August, 1986	Franck
4627602	Mechanical lifting device	December, 1986	Sporck
4640548	Chair with an adjustable backrest	February, 1987	Desanta
4641885	Work chair having a vertically adjustable chair support	February, 1987	Bräuning
4652050	Chair tilt mechanism	March, 1987	Stevens
4660887	Ergonomic support	April, 1987	Fleming et al.
D289591	Chair control unit	May, 1987	Groseth
4664445	Tilting mechanism for a chair seat or the like	May, 1987	Groseth
4685730	Seat, especially work seat, with several positions	August, 1987	Linguanotto
4691961	Recliner with headrest	September, 1987	Rogers, Jr. et al.
4693515	Headrest for an automotive vehicle seat	September, 1987	Russo et al.
4703974	Seat furniture	November, 1987	Bräuning
4711491	Swivel tilt mechanism for chair	December, 1987	Ginat
4713854	Constant force cushion	December, 1987	Graebe
4720146	Vehicle seat headrest apparatus and method	January, 1988	Mawbey et al.
4730871	Adjustable back rest	March, 1988	Sheldon
4733910	Article of furniture	March, 1988	Brennan
4752101	Tilt control arrangement for office furniture chair	June, 1988	Yurchenco et al.
4758045	Seat furniture	July, 1988	Edel et al.
D296959	Chair	August, 1988	Gusrud
4761033	Chair	August, 1988	Lanuzzi et al.
4765679	Chair having a seat with front and rear seat portions being hinged to each other	August, 1988	Lanuzzi et al.
4776633	Integrated chair and control	October, 1988	Knoblock et al.
4778218	Adjustable headrest	October, 1988	Suman
4796952	Chair with hinged backrest	January, 1989	Piretti
4811986	Adjustable lumbar support	March, 1989	Hattori et al.
4823417	Core structure and method of its manufacture	April, 1989	Fukuichi
4830430	Split-back chair, particularly office chair	May, 1989	Schäfer
4834454	Office chair with tiltable seat and back	May, 1989	Dicks
4848837	Chair having a pelvis-hip support adjustable relative to a front seat portion	July, 1989	Völkle
4848838	Curved articulating headrest support bar	July, 1989	McCrackin et al.
4852943	Pedestal chairs	August, 1989	Roper
4863218	Articulated headrest mechanism	September, 1989	McCrackin
4869448	Head restraint for vehicles	September, 1989	Kenyon
4869552	Flexible backrest assembly for a chair	September, 1989	Tolleson et al.
4871208	Chair tilt control mechanism	October, 1989	Hodgdon
4881777	Apparatus and method of utilization thereof of a profile headrest	November, 1989	Dorshimer
4889385	Chair seat-and-back support	December, 1989	Chadwick et al.
4909472	Pivoting support for chairs, seats and the like	March, 1990	Piretti
4914836	Cushioning and impact absorptive structure	April, 1990	Horovitz
4915449	Chair with a pivoting seat	April, 1990	Piretti
4943114	Chair backrest linkage mechanism	July, 1990	Piretti
4951995	Arm height adjustment mechanism for a chair	August, 1990	Teppo et al.
4962962	Piece of seating furniture	October, 1990	Machate et al.
4965899	Air cushion for chair and chair utilizing the air cushion	October, 1990	Sekido et al.
4979778	Synchrotilt chair	December, 1990	Shields
4981326	Ergonomic chair	January, 1991	Heidmann
4988145	Seating furniture	January, 1991	Engel
5009466	Reclining chair	April, 1991	Perry
5009467	Adjustable armrest for chair	April, 1991	McCoy
5013272	Rafting cushion	May, 1991	Watkins
5015034	Upholstery system	May, 1991	Kindig et al.
5022709	Springing and wrap-around element for a seat and/or backrest, and seat embodying the same	June, 1991	Marchino
5024484	Adjustable sitting device	June, 1991	Buchacz
5026120	Headrest assembly for vehicle seats	June, 1991	Takeda et al.
5029822	Device for adjusting the inclination of the backrest of a seat	July, 1991	Selzer
5039567	Resilient panel having anisotropic flexing characteristics and method of making same	August, 1991	Landi et al.
5044027	Cushion construction	September, 1991	Moon
5044030	Multiple layer fluid-containing cushion	September, 1991	Balaton
5046780	Suspension mechanism for connecting chair backs and seats to a pedestal	September, 1991	Decker et al.
5050931	Controlled deflection front lip for seating	September, 1991	Knoblock
5050933	Stacking chair with collapsible arms	September, 1991	Tornero et al.
5052068	Contoured seat cushion	October, 1991	Graebe
5052753	Adjustable sitting device	October, 1991	Buchacz
5076643	Lumbar support	December, 1991	Colasanti et al.
5080430	Reclining chair	January, 1992	Castro
5100201	Passive ergonomic work chair	March, 1992	Becker, III et al.
5101811	Fitted seating apparatus and manufacture	April, 1992	Brunswick
5102196	Chair provided with a backrest	April, 1992	Kaneda et al.
5108150	Head rest and neck support assembly	April, 1992	Stas et al.
5113540	Fluid cushion with passages for ischial spines	May, 1992	Sereboff
5121934	Suspension mechanism for connecting chair backs and seats to a pedestal	June, 1992	Decker et al.
5137329	Articulated lumbar support for a seat	August, 1992	Neale
5144708	Check valve for fluid bladders	September, 1992	Pekar
5160184	Controller for seating and the like	November, 1992	Faiks et al.
5171209	Dynamic support for preventing back-ache in a sitting position	December, 1992	Gamba
5172436	Mattress cushion	December, 1992	Masuda
5190348	Self-inflating support device including curved memory plate	March, 1993	Colasanti
5195199	Fluid cushion	March, 1993	Sereboff
5249839	Split back chair	October, 1993	Faiks et al.
5251958	Synchronous adjusting device for office chairs or the like	October, 1993	Roericht et al.
5288134	Seat assembly with integrated seat cushion and seat track frame	February, 1994	Hewko et al.
D345060	Chair	March, 1994	Duncan
5292097	Work surface support	March, 1994	Russell
5304271	Method of making a fluid cushion	April, 1994	Gusakov
5308028	Headrest support for a wheelchair	May, 1994	Kornberg
5308142	Chair with arm mounted motion control	May, 1994	Forslund, III et al.
5308145	Reclining chair	May, 1994	Koepke et al.
5314235	Portable back support	May, 1994	Johnson
5314237	Reclining chair	May, 1994	Koepke et al.
5314240	Shell structure for use with a chair having synchronously moving seat and seat back	May, 1994	Ishi et al.
5320409	Seat apparatus for vehicle	June, 1994	Katoh et al.
5324096	Adjustable height chair arm	June, 1994	Schultz
5330255	Seat integrated inflatable neck support	July, 1994	Stawicki
5340191	Reclining chair having pop-up headrest	August, 1994	May
5346283	Dental patient chair with an adjustable headrest	September, 1994	Steininger et al.
5346284	Seating furniture armrest	September, 1994	Dauphin
5348372	Tilting control assembly for chair	September, 1994	Takamatsu et al.
5348415	Locking device	September, 1994	Carlsson
5354120	Reclining chair	October, 1994	Völkle
5368365	Adjustable arm rest assembly	November, 1994	Feldberg
5372487	Inlet check valve for pump mechanism	December, 1994	Pekar
5382079	Adjustable arm attachable to a chair body	January, 1995	Wilson et al.
5388892	Mechanism for the relative positioning of telescoping members	February, 1995	Tornero
5393124	Armrest assembly	February, 1995	Neil
5401077	Ergonomically improved chair or armchair	March, 1995	Hosoe
5415459	Adjustable width arm rest	May, 1995	Schultz
5417473	Chair mechanism providing for an inclination range and inclination stop means	May, 1995	Braüning
5419617	Detachable chair arm	May, 1995	Schultz
5435626	Armrest-adjusting mechanism	July, 1995	Lai
5439267	Chair with adjustable arm assemblies	August, 1995	Peterson et al.
5444881	Anatomical support apparatus	August, 1995	Landi et al.
5452937	Plate for connecting the seat, back and legs, especially for chairs	September, 1995	Piretti
5484187	Chair armrest adjustment mechanism	January, 1996	Doerner et al.
5486035	Occupant weight operated chair	January, 1996	Koepke et al.
5487591	Back shell with selective stiffening	January, 1996	Knoblock
5505521	Sprung seat frame	April, 1996	Meiller et al.
5524966	Folding chair with tilting backrest	June, 1996	Piretti
5542743	Task chair	August, 1996	Olson et al.
5547252	Office chair	August, 1996	Pfenniger
5558399	Seat and lumbar motion chair, assembly and method	September, 1996	Serber
5560682	Adjustment mechanism for a chair	October, 1996	Brown	297/374
5562324	Lumbar support actuation	October, 1996	Massara et al.
5567010	Adjustable lumbar support	October, 1996	Sparks
5567011	Cushion for anatomical support, especially for the lumbar and cervical regions, to fit onto seat backs	October, 1996	Sessini
5575534	Work chair	November, 1996	Yu
5577807	Adjustable chair actuator	November, 1996	Hodge et al.
5580127	Chair with tilting backrest	December, 1996	Piretti
5584533	Chair with variable inclination of the seat and backrest	December, 1996	Schrewe
5586810	Adjustable headrest	December, 1996	Liu
5590934	Adjustable chair-armrest assembly	January, 1997	Gibbs
5595806	Mat for bearing and supporting objects, especially for packaging	January, 1997	Korfmacher
5597208	Armrest assembly	January, 1997	Bonutti
5599067	Adjustable arm rest assembly	February, 1997	Schuelke et al.
5605376	Method for inclining a chair seat, and chair having an inclinable seat	February, 1997	Kogai
5611598	Chair having back shell with selective stiffening	March, 1997	Knoblock
5613736	Removable headrest	March, 1997	Schaked et al.
5617595	Contoured seat cushion comprised of honeycomb cores	April, 1997	Landi et al.
5620233	Adjusting mechanism for selectively positioning chair components	April, 1997	Corwin
5630647	Tension adjustment mechanism for chairs	May, 1997	Heidmann et al.
5637076	Apparatus and method for continuous passive motion of the lumbar region	June, 1997	Hazard et al.
5641203	Adjustable arm rest assembly	June, 1997	Van De Riet et al.
5645317	Child seat apparatus	July, 1997	Onishi et al.
5647638	Height-adjustable chair arm assembly	July, 1997	Ritt et al.
5649740	Chair tilt control mechanism	July, 1997	Hodgdon
5649741	Adjusting mechanism	July, 1997	Beggs
5655814	Adjustable chair-armrest assembly	August, 1997	Gibbs
5660438	Chair having ergonomic lumbar support cushion	August, 1997	Tedesco
5660439	Integrated seat and back and mechanisms for chairs	August, 1997	Unwalla
5664842	Height-adjustable armrest unit for a chair	September, 1997	Tseng
5666861	Armrest adjusting mechanism	September, 1997	Fee et al.
5667277	Height adjustable arm rest assembly	September, 1997	Van De Riet
5669665	Car seat cushion	September, 1997	Nowak
5676483	Laterally adjustable armrest for a chair	October, 1997	Koubek
5678891	Dynamic combination seating and backrest support system	October, 1997	O'Neill et al.
5704688	Chair	January, 1998	Schrewe et al.
5711575	Office chair and adjustable lumbar support therefor	January, 1998	Hand et al.
5713631	Dynamic backrest support system	February, 1998	O'Neill et al.
5725277	Synchrotilt chair	March, 1998	Knoblock
5749628	Vertically adjustable chair arm with rotatable armrest	May, 1998	Synder et al.
5755488	Chair with adjustable seat	May, 1998	Beda et al.
5765804	Pneumatic support colunm for a chair	June, 1998	Stumpf et al.
5765914	Chair with a tilt control mechanism	June, 1998	Britain et al.
5765919	Adjustable arm-rest	June, 1998	Karlsson et al.
5769497	Arm support structure	June, 1998	Tsai
5772282	Tilt control mechanism for a chair	June, 1998	Stumpf et al.
5775774	Tilt mechanism for chairs	July, 1998	Okano
5791733	Adjustable lumbar support	August, 1998	van Hekken et al.
5791735	Headrest assembly with user actuacted pivotal support assembly	August, 1998	Helman
5791736	Ergonomic seating apparatus with inclined femoral portion	August, 1998	Herbert
5795026	Height adjustable chair arm	August, 1998	Dral et al.
5797652	Lumbar support adjustment	August, 1998	Darbyshire
5806927	Adjustable lumbar seat support	September, 1998	Schneider
5810439	Forward-rearward tilt control for chair	September, 1998	Roslund, Jr.
5823619	Vehicle seat	October, 1998	Heilig et al.
5826940	Reactive multi-position chair	October, 1998	Hodgdon
5829839	Height-adjustable chair arm assembly having gear-type adjusting mechanism	November, 1998	Wilkerson et al.
5839786	Adjustable armrest	November, 1998	Cvek
5842264	Chair construction and method of assembly	December, 1998	Roossien et al.
5845964	Writing tablet assembly	December, 1998	Phoon
5848823	Chair armrest adjuster	December, 1998	Su
5853223	Height-adjustable chair arm assembly	December, 1998	Ritt et al.
5860699	Adjustable lumbar seating system	January, 1999	Weeks
5860701	Seating furniture component or the like with a coupled backrest and seat adjustment	January, 1999	Jungjohann et al.
5868466	Flexible membrane back support	February, 1999	Massara et al.
5868467	Seating furniture component or the like with a coupled backrest and seat adjustment	February, 1999	Moll
5871256	Method for inclining a chair seat and chair having an inclinable seat	February, 1999	Kogai
5871258	Chair with novel seat construction	February, 1999	Battey et al.
5876097	Adjustable armrest device	March, 1999	Cao
5884975	Chair armrest	March, 1999	Su
5890245	Disposable ventilating mattress and method of making same	April, 1999	Klearman et al.
5895095	Adjustable armrest assemblies for chairs	April, 1999	Chen
5902011	Office chair and adjustable lumbar support therefor	May, 1999	Hand et al.
5904397	Seating unit comprising two adjacent, pivotal support elements	May, 1999	Fismen
5909923	Chair with novel pivot mounts and method of assembly	June, 1999	DeKraker
5909924	Tilt control for chair	June, 1999	Roslund, Jr.
5918940	Seat having an adjusting mechanism for adjusting height of head rest	July, 1999	Wakamatsu et al.
5927804	Vehicle occupant protection apparatus	July, 1999	Cuevas
5927811	Adjustable chair-armrest assembly	July, 1999	Tseng
5931531	Chair having adjustable synchronous tilting	August, 1999	Assmann
5931536	Adjustable armrest of a chair	August, 1999	Wu
5931537	Adjustable chair arm assembly	August, 1999	Gollin et al.
5934749	Vehicle seat with removable bolsters and pivoting headrest members	August, 1999	Pond et al.
5934758	Membrane chair	August, 1999	Ritch et al.
D413875	Arm/wrist rest	September, 1999	Lawrence
5951109	Chairback with side torsional movement	September, 1999	Roslund, Jr. et al.
5954393	Chair with removable worksurface	September, 1999	Perrin
5957534	Chair	September, 1999	Wilkerson et al.
5964503	Chair	October, 1999	Inoue
5967608	Pneumatic lumbar adjustment system	October, 1999	Van Sickle
5967613	Wheelchair support and attachment system	October, 1999	McKeever
5971481	Chair, specially an office chair	October, 1999	Emmenegger et al.
5971484	Adjustable armrest for chairs	October, 1999	Lamart et al.
5975632	Chair having a backrest with an adjustable contour	November, 1999	Ginat
5975634	Chair including novel back construction	November, 1999	Knoblock et al.
5975636	Assembly for filling void between cushions of reclining seats	November, 1999	Koch et al.
5975637	Adjustable vehicle seat	November, 1999	Geuss et al.
5975639	Armrest for ergonomic chair	November, 1999	Wilson et al.
5979984	Synchrotilt chair with forwardly movable seat	November, 1999	DeKraker et al.
D417793	Chair	December, 1999	Ritch et al.
5997093	Adjustable chair arm	December, 1999	Gollin et al.
5997094	Stackable chair with lumbar support	December, 1999	Cvek
6010189	Synchronized chair seat and backrest tilt control mechanism	January, 2000	Hybarger et al.
6015187	Tilt control for chair	January, 2000	Roslund, Jr. et al.
6017091	Adjustable armrest assembly	January, 2000	Cao
6022078	Headrest of a seat with adjustable positioning rods	February, 2000	Chang
6027169	Forward-rearward tilt control for chair	February, 2000	Roslund, Jr.
6030041	Back pad adjusting structure	February, 2000	Hsiao
6035901	Woven fabric membrane for a seating surface	March, 2000	Stumpf et al.
6039397	Tilt back chair control	March, 2000	Ginat
D423261	Chair	April, 2000	Ritch et al.
6045183	Child seat for vehicles	April, 2000	Weber
6045191	Arm-rest for a chair and a chair comprising this arm-rest	April, 2000	Piretti
6050634	Device for adjusting height of an armrest for chair	April, 2000	Yamagishi et al.
6053574	Device for adjusting the tilting resistance of a chair seat	April, 2000	Opsvik
6053577	Chair with adjustable armrest	April, 2000	Arko et al.
6053578	Multi-adjustable armrest assembly	April, 2000	van Hekken et al.
6056360	Adjustable lumbar seat support	May, 2000	Schneider
6056361	Articulated support chair	May, 2000	Cvek
6059363	Chairback with side torsional movement	May, 2000	Roslund, Jr. et al.
6059368	Office chair	May, 2000	Stumpf et al.
6059370	Wheelchair seat back pelvic support system	May, 2000	Kanyer et al.
6062646	Adjustable-height armrest, in particular for an office chair	May, 2000	Bock
6062647	Adjustable armrest assembly	May, 2000	Mei
6074012	Adjustable armrest device	June, 2000	Wu
6076892	Multi-adjustable armrest assembly	June, 2000	van Hekken et al.
6079785	Chair having adjustable lumbar support	June, 2000	Peterson et al.
6086153	Chair with reclineable back and adjustable energy mechanism	July, 2000	Heidmann et al.
6098000	Interactive, individually controlled, multiple bladder seating comfort adjustment system and method	August, 2000	Long et al.
6106069	Universal seat carrier panel for office chairs	August, 2000	Bock
6106070	Height-adjustable chair arm assembly	August, 2000	Ritt et al.
6116688	Chair	September, 2000	Wilkerson et al.
6116695	Chair control having an adjustable energy mechanism	September, 2000	Heidmann et al.
6120096	Mechanical device for synchronous movement of the backrest and seat of a chair	September, 2000	Miotto
6120099	Head-rest	September, 2000	Reikerås et al.
6129419	Adjustable comfort seat	October, 2000	Neale
6132001	Adjustment device for an arm of a chair	October, 2000	Su
6139106	Headrest for dental use	October, 2000	Aldridge
6139107	Armrest adjusting mechanism	October, 2000	Lee
D433854	Ergonomic stool	November, 2000	Diffrient
6149231	Headrest with gas bag module	November, 2000	Wüstholz
6149236	Chair frame, control mechanism and upholstery	November, 2000	Bräuning
D435746	Chair arm	January, 2001	Diffrient
D436457	Chair	January, 2001	Ambasz
D436749	Chair	January, 2001	Arad
6168236	Easy-to-assemble/recycle armrest	January, 2001	Chen
6168237	Adjustable armrest for chairs	January, 2001	Lamert et al.
6168239	Seat back with shaped internal ribs	January, 2001	Conner et al.
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WO/1995/000052	January, 1995			IMPROVED ANATOMICAL SUPPORT APPARATUS
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WO/1996/007344	March, 1996			ADJUSTABLE BACK SUPPORT
WO/1996/039900	December, 1996			ERGONOMIC CHAIR
WO/1996/039901	December, 1996			ADJUSTABLE ARM REST ASSEMBLY
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WO/1998/008424	March, 1998			CHAIR
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WO/1998/048668	November, 1998			CHAIRBACK WITH SIDE TORSIONAL MOVEMENT
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WO/1999/027820	June, 1999			ADJUSTABLE ARMREST FOR CHAIRS
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WO/2000/022960	April, 2000			ADJUSTMENT MECHANISM, BACK COVER AND ARM REST FOR A CHAIR
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WO/2000/024295	May, 2000			UNIVERSAL TILT MECHANISM FOR A CHAIR
WO/2000/024296	May, 2000			TILT MECHANISM FOR CHAIR HAVING ADJUSTABLE SPRING CHARACTERISTICS
WO/2000/053058	September, 2000			HEIGHT ADJUSTEMENT DEVICE, PARTICULARLY FOR THE SEAT BACK PORTION AND ARM-RESTS IN OFFICE CHAIRS
WO/2000/064311	November, 2000			PADDING FOR A SEAT OR A RECLINING PIECE OF FURNITURE WITH A DESORBENT MOISTURE ACCUMULATOR
WO/2000/072730	December, 2000			WORKING SURFACE ADJUSTMENT
WO/2000/074531	December, 2000			ERGONOMIC CHAIR
WO/2001/003548	January, 2001			CHAIR, ESPECIALLY AN OFFICE SWIVEL CHAIR
WO/2001/039633	June, 2001			CHAIR
WO/2001/091614	December, 2001			CHAIR
WO/2002/032261	April, 2002			OFFICE CHAIR

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Barfield, Anthony D.

Workman Nydegger

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patent application Ser. No. 10/949,501, filed Sep. 24, 2004, now abandoned which is a divisional application of U.S. patent application Ser. No. 09/953,816, filed Sep. 17, 2001, Pat. No. 6,817,667, which claims priority to U.S. Provisional Application No. 60/236,933, filed Sep. 28, 2000 and which claims priority to Australian Application No. 54083/01, filed Jun. 28, 2001, which applications are hereby incorporated by reference.

What is claimed is:

1. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame and to increase in rearward tilt angle so that a first portion of the rearward portion that is closest to the fold has a greater net increase in height than a second portion of the rearward portion that is farthest from the fold, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion.

2. The chair as claimed in claim 1 wherein the seat portion is constructed of a resiliently flexible material.

3. The chair as claimed in claim 2 wherein the seat portion comprises a panel which has apertures to enhance its flexibility.

4. The chair as claimed in claim 1 wherein the seat portion takes the form of a panel and stiffening webs are provided which offer resistance to folding towards the rear of the seat portion and lesser amount of resistance to flexing towards the forward edge of the seat portion.

5. The chair as claimed in claim 4 wherein the stiffening webs are tapered to offer the progressively increasing resistance to folding from the front edge of the seat portion towards the rear.

6. The chair as claimed in claim 1 wherein the rearward portion of the seat portion is supported, at least in part, by the recline mechanism and the forward portion is substantially unsupported.

7. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion, forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, with a consequent folding of the seat portion about the transverse fold under the weight of the occupant, the recline mechanism comprising a four bar linkage comprising: a main support forming part of the supporting frame; a second linkage comprising the seat portion or a guide relative to which the seat portion is selectively movable; a front support linkage extending between the main support and the second linkage; and a drive linkage wherein the drive linkage is pivotable about a drive axis through the main support, the drive linkage being connected to the guide and being operably linked to be driven about the drive axis by rearward recline action of the back portion to bring about the net increase in height of the second linkage on rearward recline action of the back.

8. The chair as claimed in claim 7 wherein two such four bar linkages are defined on opposite sides of the chair.

9. The chair as claimed in claim 8 wherein the main support is selectively height adjustable.

10. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion, forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion, the seat portion being adjustable in position between a forward extended position and a rearward retracted position such that the positioning of the transverse fold is variable as a function of the seat depth position; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, with a consequent folding of the seat portion about the transverse fold under the weight of the occupant.

11. The chair as claimed in claim 10 wherein the recline mechanism includes at least one guide and the seat portion is slidable relative to the guide between the extended and retracted positions, the guide including a fixed portion about which the seat portion folds.

12. The chair as claimed in claim 11 wherein the guide has an upper surface having a forward portion with an upwardly facing convex shape whereby a transition in curvature defines the transverse fold position of the seat portion.

13. The chair as claimed in claim 11 wherein the recline mechanism comprises a four bar linkage comprising four elements as follows: a main support forming part of the supporting frame; the guide; a front support linkage extending between the main support and the guide; and a drive linkage wherein the drive linkage is pivotable about a drive axis through the main support, the drive linkage being connected to the guide and being operably linked to be driven about the drive axis by rearward recline action of the back portion to bring about the net increase in height of the guide on rearward recline action of the back.

14. The chair as claimed in claim 13 wherein two such four bar linkages are defined on opposite sides of the chair.

15. The chair as claimed in claim 14 wherein the back portion is pivotally connected to the main support at a recline axis.

16. The chair as claimed in claim 15 wherein the recline axis is located below the seat portion.

17. The chair as claimed in claim 16 wherein the recline axis is located below the ischial protuberosities of the chair occupant.

18. The chair as claimed in claim 13 wherein the back portion is biased against reclining by a recline biasing device.

19. The chair as claimed in claim 18 wherein the recline biasing device comprises one or more springs.

20. The chair as claimed in claim 19 wherein two back extension arms substantially rigidly extend from the back portion and pivotally connect the back portion to the main support, the one or more springs being held by one or both of the back extension arms, with the spring(s) acting against the main support.

21. The chair as claimed in claim 20 wherein the biasing force of the recline biasing device is adjustable.

22. The chair as claimed in claim 21 wherein two springs are provided, being a first spring and a second spring, both of which operate in the manner of leaf springs with the second spring being clampable against the first spring with the combination having a resultant spring rate, with the degree of clamping being variable to adjust the resultant spring rate.

23. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion, wherein the recline mechanism is operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the entire seat portion is moved in a horizontal direction relative to the supporting frame.

24. The chair as claimed in claim 23 wherein the back portion comprises a flexible frame which is flexible or at least flexible at a part corresponding to the lumbar region of the occupant.

25. The chair as claimed in claim 24 wherein the flexibility of the back portion is adjustable.

26. The chair as claimed in claim 25 wherein the flexibility adjustment takes place automatically in response to the weight imparted by the occupant on the seat portion with, at least beyond a predetermined threshold in weight, the larger the weight, the greater the stiffness imparted to the back portion.

27. The chair as claimed in claim 26 wherein the flexibility adjustment takes place through the use of a tensionable biasing device comprising at least one leaf-type spring lying against the back portion at a lower region thereof.

28. The chair as claimed in claim 27 wherein the recline mechanism comprises a four bar linkage comprising four elements as follows: a main support forming part of the supporting frame; a second linkage comprising the seat portion or a guide relative to which the seat portion is selectively movable; a front support linkage extending between the main support and the second linkage; and a drive linkage wherein the drive linkage is pivotable about a drive axis through the main support, the drive linkage being connected to the second linkage and being operably linked to be driven about the drive axis by rearward recline action of the back portion to bring about a net increase in height of the second linkage on rearward recline action of the back; and further wherein an interconnecting linkage interconnects the leaf-type spring with the drive linkage such that, at least beyond the predetermined threshold, the weight on the seat causes the leaf-type spring to flex against the back portion to impart greater stiffness thereto.

29. The chair as claimed in claim 28 wherein a supplementary spring is provided, whereby weight on the seat portion up to the predetermined threshold causes flexing of the supplementary spring.

30. The chair as claimed in claim 28 wherein two four bar linkages are defined on opposite sides of the chair, there being two such leaf-type springs on opposite sides of the chair with two such interconnecting linkages, wherein each interconnecting linkage is disposed directly between the associated leaf-type spring and the associated drive link.

31. The chair as claimed in claim 28 wherein a tension limit is provided to prevent over-tensioning of the tensionable biasing device.

32. The chair as claimed in claim 23, wherein at least part of the forward portion of the seat portion is flexible.

33. The chair as claimed in claim 23, wherein the stiffness of the forward portion of the seat portion differs from the stiffness of the rear portion of the seat portion.

34. The chair as claimed in claim 23, wherein the forward portion of the seat portion comprises a downwardly directed forward edge.

35. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion, wherein the seat portion comprises opposing side portions and a central portion disposed therebetween, the seat portion being supported by the recline mechanism at the opposing side portions so that the central portion of the seat portion is freely suspended and unsupported.

36. The chair as claimed in claim 35, wherein the recline mechanism comprises: a pair of spaced apart rails operably connected to the opposing side portions of the seat portion; and a pair of links, each link extending from a corresponding rail to the supporting frame, each link being rotatably mounted to the supporting frame and rotatably mounted to the corresponding rail.

37. The chair as claimed in claim 36, further comprising a seat depth adjustment mechanism securing the rails to the seat portion, the seat depth adjustment mechanism enabling selective positioning and locking of the seat portion along the rails.

38. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion, wherein the recline mechanism comprises: a pair of rails operably connected to the seat portion; and a pair of links, each link extending from a corresponding rail to the supporting frame, each link being rotatably mounted to the supporting frame and rotatably mounted to the corresponding link such that when the back portion is reclined, the pair of links facilitates movement of the entire seat portion in a horizontal direction relative to the supporting frame.

39. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion, wherein the seat portion comprises a transition zone having a plurality of transverse fold positions about which the front portion of the seat portion can downwardly fold under the weight of an occupant's legs when the occupant is seated on the seat portion during a reclining action of the back portion.

40. The chair as claimed in claim 23, wherein the forward portion of the seat portion is cantilevered from the rearward portion of the seat portion by the transverse fold such that the forward portion extends horizontally forward of the supporting frame so as to be unsupported from below.

41. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion, wherein the rearward portion of the seat portion is operatively supported by a seat depth adjustment mechanism such that the seat portion is adjustable relative to the supporting frame between a forward extended position and a rearward retracted position.

42. A chair comprising: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to obtain a net increase in height above the supporting frame, the seat portion also being configured so that a consequent downward folding of the forward portion about the transverse fold is caused by weight of an occupant's legs when the occupant is seated on the seat portion, wherein the recline mechanism comprises a plurality of supports that support the seat portion from the supporting frame such that on reclining action of the back portion, movement of the seat portion relative to the supporting frame occurs, wherein said movement of said seat portion comprises a horizontal component of movement and further comprises a vertical component of movement, wherein the vertical component of movement comprises said net increase in height of the rearward portion of the seat portion above the supporting frame.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to a reclinable chair. In particular, although not exclusively, the invention relates to a synchro-tilt type chair in which the seat portion tilts rearwardly in synchronism with reclining action of the back portion. The invention is described primarily in the context of commercial office chairs. However, the invention is not limited in its application to commercial office chairs and may have application to any other type of seating such as public seating for theatres, aircraft or domestic seating.

2. The Relevant Technology

Reclining office chairs are well known. There are certain disadvantages associated with the conventional form of reclining office chair. One of the disadvantages is that as the occupant of the chair reclines rearwardly, his head drops in height. Therefore, the eye level of the chair's occupant will not be maintained constant. This may pose a difficulty if the occupant is working at a computer terminal where it is desirable to maintain a constant eye level relative to the screen. Additionally, in meetings it is also desirable to maintain a constant eye level relative to the other attendees of the meeting. Any person who undergoes a dip in eye level may effectively drop out of the conversation.

Another difficulty with conventional reclining chairs is that relative movement between the back portion and the seat portion may lead to frictional grabbing of occupant's shirt, thereby pulling out the occupant's shirt from his trousers.

U.S. Pat. No. 5,871,258 is in respect of a reclining office chair. The seat portion of the chair has a front portion connected to a rear portion by a resilient section in order that the rear portion carries most of the occupant's weight. The seat portion is operably connected to the reclining mechanism such that as the back portion reclines, the rear portion of the seat also tilts but additionally moves in a downward and forward motion. It will be appreciated that this further only serves to exacerbate the problem of tipping eye level. In this case, not only is the occupant's head dropping on account of their reclining action but also, the rear portion of the seat supporting the occupant's weight is also moving downwardly, with the practically certain result that the eye level of the occupant will dip during reclining action.

U.S. Pat. No. 5,314,237 raises the vertical height of the seat support during recline and thereby claims to achieve consistent vertical eye level. However, the chair disclosed in this US patent suffers from another shortcoming. As the seat portion lifts, the forward edge of the seat portion will accordingly be raised and thereby act as a hard edge bearing against the back of the occupant's knees. This can lead to circulatory problems for the occupant and/or lifting of the users feet from the floor with consequent poor posture.

Flexing of seat backs in the lumbar region of the user is also a desirable feature of modern office chairs. Chair occupants come in a wide range of different sizes and weights and it is therefore necessary for chair manufacturers to produce a chair which caters for a wide range of occupant sizes and weights. A larger, weightier person will be able to flex a chair back easily. On the otherhand, a person of light build may only be able to flex the back portion with a high degree of force. Accordingly, a person of light build may not receive much satisfaction from the feature of a flexible back portion.

Another common feature of reclinable chairs is the use of recline springs to resist rearward recline. Adjustment mechanisms are often provided to adjust the spring tension of the recline springs to suit the build of the occupant of the chair. Where such adjustment mechanism operate directly against the action of the spring, e.g., by way of a rotatable knob, generally a large number of turns of the knob are required in order to gradually stiffen the spring. Otherwise, the knob would be too stiff to turn in order to bring about the required adjustment.

It is therefore an object of the present invention to provide a chair which overcomes or at least addresses some of the foregoing disadvantages.

BRIEF SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention there is provided a chair including: a supporting frame; a seat portion which is foldable about a transverse fold to define a rearward portion behind the transverse fold and a forward portion, forward of the transverse fold, the seat portion being supported above the supporting frame by its rearward portion; a reclinable back portion; and a recline mechanism with which the back portion is connected for reclining action of the back portion, the recline mechanism being operably linked to the rearward portion of the seat portion such that on reclining action of the back portion, the rearward portion is moved to increase in rearward tilt angle and to obtain a net increase in height above the supporting frame, with a consequent folding of the seat portion about the transverse fold line under the weight of the occupant.

In order to achieve a foldable seat portion, the seat portion may be flexible. The seat portion may be constructed of a flexible material such as plastic. In a preferred form of the invention, the seat portion may comprise a panel which has apertures, e.g., slots to enhance its flexibility. The slotted pattern may extend across the entirety of the panel with a specific arrangement of slots provided to increase comfort for the seat occupant. For example, the slotted panel may have the slots arranged to accommodate the ischial protuberosities of the occupant. Alternatively, the slotted pattern may simply exist in a specific zone to provide flexing about the transverse fold. The transverse fold may be shaped as a straight line, depending upon the arrangement of the slots or apertures in the seat panel or according to the manner in which the seat portion is supported. The transverse fold may alternatively take the shape of a curve lying in the plane of the seat portion.

Where the seat portion takes the form of a panel, stiffening webs may be provided which offer little resistance to flexing towards the forward edge of the seat portion and greater resistance to flexing towards the rear of the seat portion. The resistance offered may progressively increase from the front edge of the seat portion towards the rear. Accordingly, the stiffening webs may be tapered to offer the varying resistance.

In an alternative less preferred form of the invention, the seat portion may comprise the forward portion and the rearward portion being articulated.

In a preferred form of the invention, the rearward portion of the seat portion is supported, at least in part, by the recline mechanism while the forward portion is unsupported. The depth position of the seat portion may be adjustable relative to the back portion and/or the supporting base. Accordingly, the positioning of the transverse fold may be variable as a function of the seat depth position. For example, the seat portion may be moveable forward/backward relative to guides forming part of the recline mechanism with the forward edge of the guides or a transition in curvature defining the transverse fold. The ease of folding may be dependent upon the depth position of the seat portion. As described above, this may be achieved by the seat portion having an increased resistance to folding in the directly rearwardly from the forward edge of the seat portion.

The recline mechanism preferably interconnects the seat portion, the supporting frame and the back portion. In a most preferred form, the recline mechanism is in the form of a four bar linkage. The four bar linkage may be replicated on each side of the chair. Therefore, the following description of the four elements of the four bar linkage may apply to single elements or alternatively to duplicated elements on opposite sides of the chair. The first linkage is in the form of a main support. The main support may be selectively height adjustable by the user. However, the main support is in normally fixed disposition relative to the supporting frame. In the most preferred form of the invention, the main support is supported at the top of a height adjustable gas spring extending upwardly as part of the supporting frame.

The second linkage of the four bar linkage may be the seat portion itself. Where the seat portion is depth adjustable, then the second linkage may comprise a guide for the depth adjustment.

The third linkage of the four bar linkage preferably comprises a front support linkage extending between the main support and the second linkage.

The fourth linkage is preferably in the form of a drive linkage which is pivotable about a drive axis through the main support, being connected to the second linkage and being operably linked to be driven about the drive axis by rearward recline action of the back portion.

Preferably, the back portion is also supported from the main support. The back portion is preferably attached to a back attach portion which is pivotally connected to the main support at a recline axis. The recline axis of the back portion is preferably below the seat portion. In a most preferred form of the invention, the recline axis is below the ischial protuberosities of the occupant.

Preferably, the back portion is biased against reclining action by a recline biasing device. This may be in the form of a one or more springs. In a most preferred form of the invention, the biasing force is adjustable. In a preferred embodiment of the invention there may be two back extension arms extending from the back portion. These extension arms could be an integral part of the back attach portion or alternatively could be rigidly connected thereto. With the two extension arms pivotally connecting the back portion to the main support, the one or more springs are preferably held by one or both of the back extension arms, with the spring(s) acting against the main support.

Preferably there are two springs in the form of leaf springs. Preferably, the first spring has a predetermined spring rate (or spring constant). The second spring may be clamped against the first spring with the combination having a resultant spring rate with the degree of clamping being variable to adjust the resultant spring rate. Preferably, the second spring has a high spring constant in its unclamped state in order that only a small clamping adjustment is required to bring about an appreciable change in the resultant spring rate of the combination.

One or more recline abutment surfaces may define the recline limit of the back portion. Preferably, the recline abutment surfaces are provided on one or both of the back extension arms and the main support.

Furthermore, there may be provided one or more forward abutment surfaces which define the forward position of the back portion. Preferably, the forward abutment surfaces are disposed on one or both of the back extension arms and the main support. In a most preferred form of the invention, one or both of the back extension arms include a pin which travels within a slot of the main support. The slot has a base which engages against the pin when the pin reaches a position of travel within the slots corresponding to the forward position of the back portion. Additionally, cushioning may be provided to cushion the abutment between the forward abutment surfaces. This may comprise an O-ring encircling the pin.

Desirably, the invention also includes a recline lock, to lock the back portion against reclining action. The recline lock may be selectively lockable by the user. In a preferred form of the invention, the recline lock acts against a lock abutment surface on one or both of the back extension arms. Preferably, the recline lock is in the form of a push rod/bar which, when selectively operated by the user acts against the lock abutment surfaces of both extension arms at the same time.

Another preferred feature of the invention is that the back portion is flexible or at least flexible at a part corresponding to the lumbar region of the occupant. Preferably the flexibility, i.e., the stiffness is adjustable. The flexibility may be adjustable selectively, although it is preferred that the adjustment takes place automatically in response to the weight imparted by the occupant on the seat portion. Preferably, the larger the weight, the greater the stiffness imparted to the back portion.

Preferably, the adjustment can be achieved through the use of a tensionable biasing device provided to act against the flexible back portion, with a varying degree of tension to impart a varying degree of stiffness to the back portion. For example, the biasing device may be in the form of a spring. Preferably, there are two flat springs lying against the back portion at a lower region thereof adjacent the connection of the back portion to the back attach portion.

Preferably, the tensioning of the biasing device is achieved by means of an interconnecting linkage which in response to the occupant's weight on the seat portion, tensions the biasing device by a corresponding amount. Preferably, the interconnecting linkage interconnects the biasing device with the drive linkage. In a most preferred form of the invention, where the biasing device is in the form of a leaf spring lying against the back portion, the leaf spring is connected to a spring carrier forming part of the interconnecting linkage, the spring carrier being pivotally mounted to the back attached portion in a manner whereby the weight of the occupant on the seat portion is transferred through to the spring carrier so as to bend the leaf spring against the back portion. As there may be two four bar linkages provided on opposite sides of the chair, there may accordingly be provided two interconnecting linkages with two spring carriers receiving two leaf springs. The back portion may include a back frame which, in its lower regions defines a rearwardly facing channel. Preferably, each leaf spring engages within the channel on a respective side of the back frame. Preferably, each interconnecting linkage also includes two push links, each interconnecting the associated spring carrier with the associated drive linkage. The back attach portion may be in the form of a housing, i.e., the back attach housing. The spring carrier(s) and the push link(s) may be at least partly received within the back attach housing. Each leaf spring and associated spring carrier may be of integral construction.

The supporting frame may be of any type. Preferably, the supporting frame is of the conventional type with a central support and a plurality of radiating legs with castors. The supporting frame may incorporate a height adjustable gas spring.

A tension limit may be provided to prevent over-tensioning of the tensionable biasing device. For example, rotation of the spring carrier may be stopped against the back attach housing.

In accordance with a second aspect of the present invention there is provided a chair having: a supporting frame; a seat portion supported above the supporting frame; and a back portion having a flexible portion, wherein the flexibility of the flexible portion is adjustable as a function of the weight of an occupant on the seat portion.

The seat portion and the back portion could be integral or alternatively could be discrete portions of the chair. Preferably, a recline mechanism is provided which interconnects the seat portion, the back portion and the supporting base.

The flexibility of the flexible portion may be adjustable by way of a stiffness adjustment device. This may be in the form of a tensionable biasing device. The tensionable biasing device preferably acts against the flexible portion to impart stiffness thereto with the tension of the biasing device being adjustable as a function of the weight of an occupant on the seat portion. The tensionable biasing device may be interconnected by a means of an interconnection with the seat portion, the seat portion being moveable on the application of weight from an occupant whereby the weight of the occupant acts through the interconnection to adjust the biasing device as a function of the weight of the occupant. Preferably, the interconnection comprises a series of links to transfer the weight of the occupant into increased tension of the biasing device. Preferably, the biasing device is in the form of one or more springs such as leaf springs and the interconnecting linkage acts to bend the one or more springs against the flexible portion of the back, thereby increasing the stiffness of the flexible portion.

In a most preferred form of the invention, the interconnection includes a four bar synchro-tilt mechanism which tilts the seat portion synchronously with back recline. The four bar synchro-tilt mechanism may take the form of the four bar linkage described above in accordance with the first aspect of the present invention. The drive link of the four bar linkage may be connected to a push link which is in turn connected to a spring carrier as described above in accordance with the first aspect of the invention.

A tension limit may be provided to prevent over-tensioning of the tensionable biasing device. This may be in the form of a physical stop which acts against the spring carrier.

In accordance with a third aspect of the present invention there is provided a chair having: a supporting frame; a main support supported by the supporting frame; a seat portion supported above the supporting frame; a reclinable back portion operably connected with the main support for reclining action relative to the main support; a first recline spring operably connected between the main support and the reclinable back portion for resisting reclining action of the back portion; and a second recline spring operably connected between the main support and the reclinable back portion; the second recline spring being selectively adjustable to impart a varying amount of resistance to the reclining action of the back portion.

The resistance imparted by the second spring may be adjustable between a nil amount and a predetermined amount.

The first recline spring may be in the form of a leaf spring or spring bar. The second recline spring may also be in the form of a leaf spring or spring bar. The leaf springs may be flat or bent. Preferably, the first leaf spring is substantially flat when untensioned, although desirably the first leaf spring is pretensioned into a curved configuration in order to provide an initial resistance to reclining action. A forward limit may be provided to define the forward active position of the back portion. The first recline spring and selectively the second recline springs bias the back portion into the forward active position. Additionally, a rearward recline limit may also be provided to define the rearmost position of the back portion.

In one form of the invention, the adjustment device brings about adjustment of the length of the second leaf spring. Alternatively, the adjustment device may bring about adjustment of the curvature of the second leaf spring. This may be achieved by way of a cam having a cam surface bearing against the second spring, the position of the cam being moveable to adjust the curvature of the second spring. Preferably, the cam is pivotable about a pivot axis with the cam sur