CA2103263A1 - Unitary chair with resilient bottom and back - Google Patents

Abstract

2103263 9318686 PCTABS00025 A unitary chair support member (316) comprises an elongated spine (386) having first (388) and second (390) ends. The first end (388) is supported by a chair base and the second end (390) is integrally formed with a seat back pan (392). Intermediate the ends of the spine (386) a seat pan member (394) is integrally formed.
The seat pan member (394) is defined by a peripheral edge (398) extending continuously about the seat's perimeter, and a pair of forward and rearward relieved portions (400, 402) spaced inwardly of the edge. The spine (386) is joined integrally to the seat pan (394) centrally of each relieved portion such that at the forward relieved portion (402) the spine (386) extends downwardly to attach to the chair base and at the rearward relieved portion (400), the spine (386) extends upwardly to join to the back pan (392), and provides resilient support surfaces for comfortably supporting the user.

Description

WO g3/18686 PCI`/US92/06272 21~,~253 UNlTARY CHAIR WIT~I RESILIENT BOl-rOM AN D BACK

The present applieation is a continuation-in-part of eo-pending application Serial No 07~785,190, filed on October 31, 1991, ~hieh i6 a eontinuat~on of now abandonet application Serial No 07/454,351, filed on December 12, 1989, ~hieh i6 a eontinuation-in-part of applieation Serial No 165,74S, filed on Mareh 9, 1988 for a chair, now U S Patent No 4,889,385 T~E FIELD OF T~E INVENTION

The invention relate6 to seating and more partieularly to ehairs having one-piece seat-and-back ~upport6 B~CKGROUND OF T~E rNVE~IIg~

Chair~ having one-piece aeat-and-baek ~upport6 are ~no~n For ~a~plo, U S patent to St John, 293,813, is~uod FebruarJ 19, 1884, di~eloaes a ehair eomprising an elongated ~eat_~nd-bae~ ~upport mounted on a floor-engaging base The ~eat-and-bae~ ~upport eompri~e6 a lo~er, rigid, U-6haped seat ~upport and ~n upper relatively resilient back support extending up~ardl~ fro the eat ~upport When 8 rearward and do~nward ~oree i~ ~xert-d on the ~eat-and-back support, the upper baek ~upport defleet~ bae~ardly and downwardly Although the bae~ ~upport of St John'¢
seat-and-bae~ ~upport is flexible, the seat support thereof i6 not. Thus, ~hile the b-e~ support i8 designed to deflect do~n~ardly and bae~ardly relative to the seat support in response to an oeeupant'6 weight, the seat support i6 not 6e eonatrueted Sueh~deaign has been detenmined to be insufficient in pro~ding the neeea~ary eomfort for user6, especially in ~ork envlronments ~here the ehairs are oeeupied for extended periods of time SUBSTITUTE SHEE'r W O 93/18686 P ~ /US92/06272 It has thus been found desirsble to provide a chair one-pieee ~eat-and-baek eupport compri6ing a U-shaped seat support ~th upper and lower leg portions and an intermediate bight portion, and a back support with a lower bight portion and an uprl~ht bae~ portion, ~herein both bight portion~ are flesible thereby enabling the seat ~upport and the back support to ad~ustably respond at different rates of deflection to an oeeupant'~ ~elght Thi6 ehair d~ign ha~ been determined to be st adequate in providing the neeessary eomfort to the chair oeeupant It has also been found desirable to provide a re~ilient stiffening means, sueh a leaf spring, between the upper and lo~er leg portion~ of the seat support to strengthen the ~a~e and inerease resistanee to relative deflect~on of the upper leg portion of the aeat ~upport.

It ~hould be noted that th use of leaf ~pring6 in ehair~ to re d -t tilting of eat supports are kno~n, although ~uoh~bia-~ng meJn~ have not been u ed in chair~ of the preferred~
t~pe heretofore deseribed For exu ple, U S patent to Benzing, 3.337,265, i-sued Mareh 4, 1965, discloses a chair comprising, ~n rel ~nt part, a pair of inverted U-~haped ~ides connected by p~ir of tr~n~ver~e and longitudinal hori~ontal ~upports A
palr of U-~ha* d pring are ounted on the transverse u~port~ tantiallr~ L,~haped ~eat-and-back support is -ou~ted~on top of th- pring-~ In thi~ anner, when a rearward a~d do~n~ard foree is eYerted o~ the seat-and-baek support, same reeli~e~ doun~ardly and bae~ardly against the tension of the ~pring~

- ~ ~ In` ~addition, U.8. patent to Werner, 3,740,792, i~ued June 26, 1973, di~elos-s a chair eomprises a box-like lo~er bou-ing opon at baek and top portions thereof and mounted o~ top of a pedestal. An upper seat support is pivotally SUBSTITUTE SHEET

W 0 93/18686 P ~ /USg2/06272 -3- ~ L ~ 3 ,~r~ 3 mountod to tho housing on a horizontal shaft A number of overlapping leaf springs eurround the ~haft and engage the housing and the seat support. The springs bia6 the seat support in a hori~ontal po~ition Wh¢n a downward force i~ exerted on the seat support, the eame pivots again~t the tension of the ~pringc.

Ben~ing also provides for ad~u~tment of the leaf ~pring'- re-i-tance to deflection of the seat support relative to the ho w ing Specifically, the tension of the ~pring6 ~6 ad~u ted b~ turning a lever which displaces the springs for~ardly and rear~ardly toward and awar from the pivotal axi6 of the eat support to increase the moment arm of the spring6 and thw varr tho te~sion of the same In contra~t to the leaf spring tension ad~ustment ~ean8 di~elo~d b~ B~n~ing, it has been found de~irable to proride ten-ion ad~u t ent eana in a chair having a one-piece eeat-ant-bac~ eupport, wherein the ad~ustment ~eans ad~ustablr nB-g ~ the l-a epFing along a lo~gitudinal axis thereof to ;~ ~ne~ Je and decreaJe the effective length of the pring to tb r b~ decrea e~and~ lncrea-e, respectivelr, the spring'6 reeietasee to d fl-etion of the eeat support.
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In one a-pect, the present in~ention provides a ucit~r~ éh ir~ -upport~ r, co prlsing: an elongated ~pine portion b ing ~fir t and ~ cond ends, the fir~t end adapted to ! r b~ eupported bJ a chair~baee. The pine lncludes a seat bottom pa~ a~d ~a ~e~at~bac~ pan,~the~pan~ being integrally ~olded with the ~pine~thérebr~;~fon~ng;~the unitary chair support ~ember. The eoat~bae~pan i~locate*~at thé ~seeond end of the epine and the eat~bo~tto p~ loe-ted~aiong the epine~between the eeat back p~ and ~the flret~ ond;~ of ~;the~ ep~ne The eeat botto psn i~clude~ a ~oat~g~ urf-ce ~adapted~ to e~pport a ueer. The .
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SUBSTITUTE SHEET
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W O 93/18686 P ~ /US92/06272 so-ting surface is defined by an outer peripheral edge and including first and second relie~ed portions displaced from the peripheral edge of the seat bottom pan The spine i6 joined with ~aid ~eat bottom pan distal the peripheral edge of the seat bottom pan The portions of the seat bottom pan lying between the fir~t and second relief portions and the peripheral edge for~ ro-iliont ~upport ~urfaces for fully supporting the leg6 and tail bone area of the user The cbair ~upport members preferably formed from either glasc reinforced polyester or glass reinforced nylon and i~ foneed u~ing an in~ection ~olding proces6 Preferabl~, tbe chair base support6, and i8 secured to, the fir~t end of the elongated spinc by clampingly engaging tho elong tod spine along the outer peripher~ of the first end of the ~iino. Preferably~, the first and socond relief portions of the ~eat botto pan form eans for retaining an inner shell _ er The invention will ~o~ be described with reference to the acc4 paD~ing dr~ing- in ~hich Figure 1 i~ a front perspective view of a chair in accordance~ith the invention Flgure 2 i6 a r ar per-pective view of the chair ~ho~n ~n Flgure 1.

Figure 3 is a side elevatlonal view of the chair ho~ ln Figure 1 , ~ :
Figure 4 i~ a ~ide el vational view of the chair ~ho~n ln lgure 1 lllustrat~ng the chair tilt~ng capability SUBSTITUTE SHEET

W 0 93/18686 _5_ 2 ~ ~ 3 2 6 3 P~/USg2/06272 Figure 5 iB a perspective view of a support mean6 of the chair and certain elements of a stabilizer means and one embodiment of a ten~ion control means.

Figure 6 $8 a detailed side elevational view of a Beat-atld-baCk 8-: rt of the chair.

Fig_:, 7 is a bottom view of the seat-~nd-back support.

Figure 8 is a fragmented perspective view of a 6eat support of the ~eat-and-back support illu6trating the stabilizer ~can6 and the tcn~ion control ~ean6.

Figurc 9 is an exploded ~iew of the stabilizer mean6.

F~gure 10 is a perspoctive view of a stiffening means of the ch~lr unted to a cradle of the tension control oean~.

F~gure 11 is a front elevational view of the st~ffening can~ and the cradle ~ho~n in Figure 10.

Figure 12 is a ~ide elev~tional view of a ~econd e~bodiment of the ten~ion control means.

Flgure '13 i~ a sid elevational view of a thirt e~b,odi ent of the tension control.means.

Figure 14 is an exploded ~iew of an armre6t mounting means of the chair.
~ ' Figure 15 i8 a perspective view of the second eubodiment of the tension control meana illustrated in Figure 12.

SUBSTITUTE SHEET

W O 93/18686 P ~ /US92/06272 0 3 2 S 3 6 ~; !

Figure 16 iB a front perspective view of a 6econd ombodimont of the chair of tbe present invention.

Figure 17 i8 a rear perspective view of the chair of Figure 16.

Figure 18 i8 an exploded view of a second embodiment of the ~upport means of the pre6ent invention (also called the ~pine ~upport and ad~ w tment aseembly).

Figure 19 is a side elevational view of the chair of Figure 16.

Figure 20 i6 a cros~-sectional view taken sub~tantially along lines 20-20 of Figure 19.

Figure 21 is a partial cros~-sectional view taken sub~t~ntiallr along lino~ 21-21 of Figure 20.

Figurc 21A io a partial croos-sectional view takcn ~ub~tantially along lines 21A-21A of Figure 21.

Figure 22 is a partial cro60-sectional view taken ~ub~ta~tiall~ along lines 22-22 of Figure 21.

Figure 22A i~ a partial cross-~ectional view ta~en ~ub~tantiall~ along lines 22A-22A of~ Figure 22.

Figure 23 is a par~ial cross-sectional view ta~en ~ub-tanti 11~ along lines 23-23 of Figure 21.

~ Fi:gure 24 is a front perspcctive view of the unitary chair ~upport ~cmbcr of the present invention. ~
, ~ Figure 25 i6 a bottom perspective view of the unltar~ chalr ~upport member of the present invent~on.

SUBSTITUTE SHEET

W O 93/l8686 PCT/~S92/06272 Figure 26 is a cross-sectional view taken substantially along lines 26-26 of the unitary chair eupport ~ember of Figurc 24 Figure 27 le a bottom view taken substantially ~long line~ 27-27 of the unitar~ chair ~upport ~ember of Fi~ure 24 Figure 28 is a cro~e-sectional view taken ~ub~tantially through lines 28-28 of Figure 27 Figure 29 is a partial cross-sectional view ta~en eubstantially through lines 29-29 of Figure 27 Flguro 30 1~ a partial cross-sectional view taken ~ubetantially through lines 30-30 of Figure 27 Figure 31 1~ a front vie~ taken eubstantially along l~ne~ 31-31 of the unitar~ chalr 8upport ~ember of Figure 24.
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Flgure'~32 i- a partial cross-sectional view taken ub-tant~all~ through line8 32-32 of~N gure 31.

Figure 33 1~ a partlsl cro~-sectional view ta~en ~ub~t ~tiallr thtough l~no- 33-33~of Flgure 31.

N ~ure 34~ front v~e~ of the seat back ,inner hell of tho~pre~ent lnventlon~
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, ~Flgure 35~ a "partlal cross-eectional vie~ ta~en ub~tantiall~-long~ e~35-35 of the~-eat b-ck in~er shell of ~ igure 34.

',~'s'' ,~ Figur- 36 1-~'an~- embly~ho~in~the seat back inner hell of Flgure 34 aa~e~bled~to the unitary ch~ir eupport member '~ of the pre~ent ln~ ntio~.
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SUBSTITUTE SHEET

WO 93/18686 PCr/US9~/06272 -R- .
2I 0~26~

DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENTS

Referring generally to the drawing6, there i6 shown a chair 10 comprising a ca6tered base 12, a vertically ad~ustable podestal 14 mounted to base 12 a~d an elongated one-piece eat-and-bac~ support 16 mounted to the pede~tal. The seat-and-back ~upport i6 adapted to deflect downwardly and bac~wardly again6t the weight of an occupant. A resilient stiffening mean6 18 is provided for increasing the seat-and-back ~upport's resi~tance to deflection. A tension control means 20 is pro~ided for ad~usting the tension of the stiffening mean6 18.

Referring now specifically to Figure6 1-5, the chair ba~e 12 comprises a plurality of equidistantly spaced arm6 22 having mounted at outer ends 24 thereof floor engaging ca6ter6 26. Inner end~ 28 of thc arms 22 are connected by a central web 30 having a c~ntral 80c~et 32 extending therethrough. The ba6e 12 i~ preferably a o~e-piece _ ber made of cast aluminum or Z~tel (a gla~ reinforced nylon). Although the base 12 i6 illw trated as having five ar~s 22, any other number of arms can be used to provide the necessary support for the chair 10. The illu trated chair base 12 is of a similar t~pe used in conc ctlon ~ith a chair ~anufactured and sold under the trad _ r~ ~QU~ b~ ~or~cn Millcr, Inc., of Zeeland, Michigan, ~pplicJnt's as-ignce of record. Ho~ever, other suitable chair ba~ kno~n in the art ay be substituted for the iIlustrated ba c 12.
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Thc pedostal 14 comprises a lower tube 34 securely rccei~ed ~ith~n the web socket 32 of the base 12 and an upper tubc 36 abovc thc lowcr tube and secureIy rotatably mounting at ~n upper end 38 thereof a support mean~ 40 preferably made of die cast alu~inum. A pneumatic air spring 42 is positioned bétwcen and partially received within the upper and lower tubes 34, 36 and co~pr~ses a piston (not shown) securely mounted to SUBSTITUTE SHEET

W O 93/18686 P ~ /US92/06272 9 2 1 ~ 3 the web 30 and a cylinder 44 secured to the ~upport mean6 40 The air ~pring 42 includes an ad~ w tment pin 46 projecting up~ardly from the uppor ax$al end (not shown) of the cylinder 44 and through a vertical bore (not shown) in the support mean6 The pin 46 is adapted to move between an upper po6ition, whore the eyl~nder and piston of the air spring 42 are held otationary in locked engage ent, and a lower pooition, where the e~linder and pi~ton are relea-ed for movement relative to each other to ~xtend or eontract the air ~pring longitudinally The ad~u t ent pin 46 is nor all~ biaoed in the upper, locked pooition. A height ad~uot ent lever 50 is pivotally mounted to the oupport mean~ 40, engage6 at an inoide end 52 of the lever the ad~uot~ent pin 46 and extends outwardly from the casting at the lever out~ide end 50 is 54 at lateral side 56 of the chair 10. When the lever aetuated by lifting upwardly on the out6ide ond of the a~e, the lever inside end 52 fsrces the pin 46 to the lo~er pooition, thereb~ releasing the piston (not sho~n) relJtive to the e~linder 44 a~d thuo allswing the pede~tal 14 to oxtend or eo~tra¢t to raise or lo~er the ehair upper portion 58. When the le~er SO io relea ed,~ the pin ~oves to the upper po d tion and the pede~tal 14 beeo e- locked in the ad~usted po d tion. A hand knob 60 io provided at the lever outside end 54 to faeiiitate m~nual pi~otal aetuation of the lever 50.

oho~ in Figures 3,4, and 6, ~he one-pieee ~at- nd bae~ oupport 16~ ount-d to the pede~tal 14 and is bent oo a- to for~ a lo~er generall~ U- haped seat support 62 op n to~ard th ehair baek~ portio~ 64 and an upper, ~o e~hat ~-~haped baek oupport 66. The ~ at upport 62 eomprioes upper and lo~er leg portions 68, 70 and a first bight portion 69 ter cdiate the leg portiono. The ~baek~upport 66 eomprises a oeeond blght portion~ 73 extend~ng ~rear~ardly and upwardly from tbe upper leg 68 and an upper back ~-upport portion 75 extend~ng ulrn rdl~ from tbe econd bight portion. The first and 6econd bl p t portion- 69, 73 are re-ilient and the upper and lower leg~
68, 70 and the upper back ~upport portlon 75 are somewhat ~tiff SUBSTITUTE SHEET

W O g3/18686 P ~ /US92/06272 2103~63 The chair seat 72 i8 mounted on the upper leg portion 68 of the seat support 62 The chair back 74 i6 ~ounted on the upper back support portion 75 of the back support 66 ~ 8 lllustrated in F~gures 5-8, the lo~er leg 70 of the U-~haped ~eat ~upport 62 form~ a down~ardly oriented cover 76 at a rear end 76 of the leg The cover 76 has a rearwardly and do~n~ardlr sloping U-shaped side wall 78 and a top ~all 80 The cover 76 i6 complementary to, slidably received on and ~ounted to the ~upport eans 40 Mounttng of the eover 76 and tbu~ the seat-and-back support 16 to the support means 40 can be achieved by any suitable mechanical mean6, such as by plurality of bolts 82 in rogistrr with a number of al~8ned hole6 84 and threaded bores 86 of the cover and support casting, re~pect1vely The cover 76 functions to protect elements of the h d ght-ad~u table pede-tal 84 de~cribed above El~ments of the ten~lon control c~n8 20 are si~ilarly protected by the cover 76 a~ ~1ll be de~cribed belo~

~ ho~n in Figures 3 and~4, ~hen the weight of an occupant i~ ~xerted on the eat-and-back eupport 16, the first and ~-cond portions 69, 73 re-ilientlr respond to deflect and ove t~e eat- nd-back ~upport do~nwardlr and back~ardlr between three g~neral d~groe~ of fle~: a full upright '~ork intensive"
po~t1On, a p rtially fl~ed "relaxed" po~it~on, and a "full tilt" po~tlon.

j In the wor~ intensive position, an occupant exerts ~ni al force on the bac~ support 66 to impart limited deflection~ thereof In the ~ork intenisive position, an occup~nt'~ ~eighè ie ~exerted do~nwardlr on the cha~r 6eat 72, -~lth so e defleetion of the seat support upper leg 68 relat~ve ,~
to th lo~er leg 70 In the rolaxed position, an occupant iB lesned s1ightl~ rear~ardlr exert~ng ~ome degree of force on the back SUBSTITUTE SHEET

W 0 93/18686 P ~ /USg2/06272 21~263 . ;, .
~upport 66 By leaning back~ardly, an occupant shifts his/her center of gravity rearwardly away from a pivot point A
Dioplacement of the center of gravity increases the moment arm abou~ pivot point ~, thereby enabling the seat-and-bac~ support 16 to flex rear~ardly and down~ardly The flexing motion cause6 the S- haped bac~ upport 66 to flatten lightly, thereby increa~ing thc angle formed bet~een the upper leg 68 of the 6eat ~upport 62 and the bac~ ~upport 66 Substantiallr maxi~Nm flex of the ~eat-and-back ~upport 16 i~ achievcd in the full tilt positlon obtained when an occupant exerts additio~al pre-sure on the bac~ support 66 In this po~ition, the outer angle bet~een the seat support upper leg 68 and the bac~ ~upport 66 i~ ~axi~i~ed by the further do~n~ard a~d rear~ard ~eat-and-bac~ ~upport 16 deflection In the full tilt po~ltion, a aignificant portion of an occupant's upper bodr ~eight i~ ~hifted to the chair bac~ 74 Therefore, the elon~ated one-piece ~eat-and-back ~upport 16 ~ adapted to re~iliently re~pond to shift6 in an occupaut'~ ~eight b~ ~oothly flexing at the first and second bi~ht portions 69, 73 thereof fro~ an upright ~ork intensi~e po~ition to a part~allr relaxed po-ition to a full tilt po6ition ~ a~ oc _ t ~hlft~ hi~/h~r ~ i p t re r~ rdly against the back ~upport 66. The novel de-i8n of the elongated onc-piece flox~bl- ~ea:t-~nd-bac~ -upport 16 i- uch that the same is dlr~ctl~- ro~pon~ive to hif~t~ in an occupant's ~eight to oothl~;bend aoong ~the ~riou~ degree~ of fled heretofore deaqribed, ~ith the upper leg ~68 of the ~eat support 62 dofIectiug at a rate differ~nt fro~ the rate of deflection of the~bac~ eupport 66. Thi- different d~flection rate i8 due to th differing donn~ rd and rear~ard load distributions exerted on the ~at-and-bac~ ~uppDrt ~hen an -occup~nt site in the chair.~ To~ att in the do~ired r d liencr, the seat-and-back ~upport~16 i~ preferablr ~ade of a glass reinforccd nylon resin, a ~uitable exa~ple of ~hich i~ ar~et-d br the DuPont Company SU~SSTITUTE SHEÉT

W 0 93/18686 P ~ /USg2/06272 ~ -12-21û321i3 under the trademark Zytel The ~eat-and-back support i~
preferably in~eetion molded from such material A polyester resin by D4Pont sold under the trademark Rynite may aleo be used Referring to Figures 1, 2, and 7, the seat support upper leg portion 68 i8 enlarget or relatively wide with respect to other portion~ of the ~eat and bac~ support 16, namely, the fir~t blght portion 69 and the lower leg portion 70 of the seat support 62 and the ~eeond bight portion 73 and the upper bac~
~upport portion 75 of the back ~upport 66 Speclfically, the bac~ ~upport portion 75 and the second bight portion 73 of the baek ~upport 66 are relatively narrow and eaeh preferably has a width of approximately four inehes along substantially the full length thereof The upper leg portion 68 of the seat 6upport 62 is appro~ atel~ 10.5 inehes in ~idth at a eentral transverse axi~ thereof. The upper leg portion tapers ns it extends for~ardly to the fir~t bight portion 69 ~hieh tapere along it6 length to the lo~er leg portion 70, the first bight portion ha~lng a JX~ N ~idth of approxi~atel~ 9.5 inehes and an averJge ~idth of approxi~ately 8 125 inehoe. The lo~er leg portion 70 of the eat support also tapers along the length thereof eontinuing from the first bight portion 69 and has a aXiD ~idth~ of 6 75 inehe6 and an a~erage ~idth of approx~ atel~ 6 ~neh~.

~With re~p et to the thie~ness of relevant portion~
-;~of the ~eat-and-bae~ ~upport 16, proferably the seeond bight , ~ ~
portion 73 i~ appro~t atelr 0.500~inehe~ in thiekness and the uppor leg portion 68 ha- a thiekne~ less thon the thic~ne6s of the ~eeond blght portion. The a~erage thie~ne~s of the upper leg portion~68 ie a ~ l -tely .2S0 inehes. The thie~ness gradient bet~een the econd bight portion and the upper leg portion 1~ gradual. In addition, the first bight portion 69 and the lo~er~leg portion al80 preferabl~ have a thickness of .250 inche~.
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SUBSTITUTE SHEET

W 0 93/t8686 P ~ /USg2/06272 -13- 21 ~32~3 .

Given the above-discu6sed preferred material co~position of the seat-and-back support 16, the forgoing di~en~ion~ thereof provide the ~ame ~th sufficient flexibility at the first and eecond bight portions 69, 73 to achie~e desired relative deflection of the upper leg portion 68 and the back upport port~on 75 ~ illustrated in Fi~ures 5, and 7-9, the chair 10 further include~ a bridle 88 (hereinafter, soDetime6 referred to as the "stabili~er ~eans") mounted to and between the upper and lo~er logs 68, 70 of thc seat support 62 and for providing ~tability to the ~ _ during deflection of the ~eat-and-back support 16. Specificall~,-the bridle 88 comprise~ an upper brac~ct 90 ~ounted to thc eat support upper leg 68 and a U-~hap d ~tabili~er br cket 92 cecured to and between the upper brac~ot a~d the support eans 40.

The brac~et 90 co~pri-es an upper plate 94 and a p d r of ~pac-d bilateral fla~ges 96 preferablr formed integral ~ith the plate. The plate 94 ~8 positioned above and mattingly _ ~ the ~at ~upport upper leg 68 by a plurality of bolte 98 r-gi~trf ~ith alig~ed holes 100 ~n the overlapping plate and ~oat 0 pport upper leg. The flacges 96 of the brackct 90 depend tc~c~ rdl~ t~herd ro and are in regi~trr ~ith a pair of spaced ~lot~ 102 e~t~dlng throu~h tho oat upport upper leg 68 ~ ~ ~ TSe U _ h ped~ ~tabilirer ~brac~et 92 i6 pivot~lly ou~t-d~to tbe brac~ t 90 at upper ~nd 104 of spaced ar~s 106 of the otabili~cr. To thi~ eDd, ea~h flange 96 of thc brackct 90 fon lng~a palr of ~pacea~legs 110 baving a includcs a slot 108 p lr of allgDed op plng~ 112 c~t~nding therethrough The upper db~ 104 of~ tho ar~e 106 are received in the slote 108 and ncludé~hole- 114 -1igne~ ~ith~the al~lgned opening~ 112 A p~ir of pin~ 116 ~tend through th aligned openings 112 and hole6 114 to p~votallg ount the ~t~blllrer ar~s 106 to the~brac~et 90 ' ' ' SUBSTITUTE SHEET

W O g3/18686 P~r/US92/06272 The U-~haped stabilizer bracket 92 ie also pivotally ~ounted at a lower bight portion 118 thereof to the support ~eans 40 in ~and~iched relationship between the ssme snd the seat ~upport lower leg 70 To this end, the support means 40 has for~ed therein a front transver~e channel 120 in whic~ a U--haped, in cro~s section, shoe 122 co plomentsry to the front tran8~er-e channel is recei~ed The bight portion 108 of the ~tabili~-r brac~et 92 rotatably engages the shoe 122 and i~
fully reccived ~ithln the chsnnel 120 such that there i8 ~ufficient clearance between the seat support lower leg 70 and the b$ght portion 118 to penDit free rotation of the same with re~pect to the support ~eans 40 Lower portions 124 of the ~tabili~er ar~s 106 are in slidable registry with a pair of paced elongated ~lot~ 126 extending through the seat support lower leg.

In operation of the one-piece ~eat-and-back support 16, wh~ a~ occupant'~ weight is exerted on the eeat support 62, the upper leg 68 thereof deflcct- do~nwardly causing the arme 106 of the ~tabili~er brac~et 92 to pivot about their mounting to the flanges 96, the ar~ lo~or ende 124 to register to a greater extent with the elongated ~lots 126 of the seat support lo~er leg 70 and tho tabili~er brac~et bight portion 118 to rotate ~lthin the front trans~er~e channel 120 of the support ean~ 40. In thi- anner, the~bridle 88 acco modates relative ov~ cnt o the upper and lo~er legs 68, 70 of the seat support 62 ~hile t tho a~e ti e perfor~ing its pri~ary functions of re~i~ti~g ~eparation of the uppcr and lower legs 68, 70 when the chair 10 i~ not occupicd and~providing lateral etability to the U _ haped ~at upport 62 during flex of the sa~e between the wor~ lnten i~e a~d full tilt positions To ad~u~t the re~i~tance to deflection of the ~eat-and bac~ upport 16 to acco od te occupants differing in weight, the ch~ir 10 i- provided with the re~ilient 6tiffening e~n~ 18 and the ten~ion control ~eang 20 Aa generally SUBSTITUTE SHEET

W O 93/18686 P ~ /USg2/06272 -lS- 21~3263 illustrated in Figures 3-5 and 8, the stiffening mean6 18 co~pri~e~ an elongated ~trap-like leaf epring mounted to and bet~een the upper and lower legs 68, 70 of the seat support 62 The geometry of the leaf spring will be hereinafter described in detail The leaf spring resist6 down~ard relative movement of the seat upport upper leg 68 when an oeeupant's weight i~
exerted thereon The leaf spring i8 preferably made of a eo0po-lte ~aterial ueh as unidireetional S-glas~ ~ith an epoxy resin (i e , gla---reinforeed opoxy) The tension eontrol mean~
ad~u ts the leaf spring's resistance to deflection of the eat-and-baek upport 16 To this end, the tension eontrol esn- 20 i~ adapted to ad~ustably engage the leaf spring along a longitudinal axis thereof to decrease and increase the effective length of the leaf ~pring to inerea~e and decrease, re~peetively, the pring's re~i~tance to relative deflection of the eat-and-baek ~upport The ten-ion eontrol mean~ 20 generally eompri~e6 an ~ng glDg ean- 123 for ad~ustably engaging the leaf spring, a ounting vean~ 125 for ovably ~ount~ng the engaging mean6 to the upport q n- 40 for ~ove~ent bet~een front and rear po~itions relative to the leaf spring and an aetuating means 127 operabl~ eonneeted to th unting ~eans for actuating movement of the ng-ging nean~ bet~een the front and rear po~ition6 In thi~ uanner, o~ _ nt of the engagi~g eans 123 to~ard the rear po~ition deere~se- the effeetive- ~o~ent an~ length between the leaf ~pring and the foree exerted on the rear portion of the eeat ~upport by the oeeupa~t, thereb~ inereasing the spring'6 re~ieta~ee to defleetion of the upper leg 70. Move ent of the en8ag~ng vean- to~ard the front position inerease6 the effeetive onent an--length to thereby deerease the spring's resistanee to defleetion of the~upper leg In this ~anner, the resilieney or re~i~tanee to deflection of the seat-and-baek support 16 ean be ad~w ted to eo fortably aeeo~modate oeeupants varying in ~elght. It e~y be ~un~ised that a relatiYely heav~ occupant ~ould ad~ w t the tension eontrol means 20 to a posltion adjscent SUBSTITUTE SHEET

21~3263 `"

the rear position to increa6e re6i6tance to deflection of the seat-and-baclc oupport 16, while an occupant of relatively light ~eight ~ould ~et the tens~on control mean~ clo6er to the front position to decrea~e the leaf 6pring'6 resistance to deflection of the ~eat-and-back eupport In one embodi~ent of the invention, illuotrated in Figures 5 and 7-11, the resilient stiffening means 18 comprises a ~ub-tantiall~r bo~-~haped leaf pring 128, having upper front and rear portion6 130, 132 and a central portlon 134. The ~pring front and rear portions 130. 132 reverse in curvature, the apexe~ of the curve~ freely ~lidably engaging front and back botto~ surfaces 136, 138 of the ~eat support upper leg 68. In addition, the leaf spring 128 i6 slidably engaged with, at the central portion 134 thereof, the tenaion control means 20 The t~ion control -an~ lidably mounted to the ~upport mean6 40 through an elongated opening 140 in the seat support lower leg 70 for ~ement between the front and rear positions heretofore de~cribed Referring no ~ ~pecifically to Figures 8 and 10-11 for a det~iled di~cu~ion of the ten-ion control mean6 20, the g #ans 123 thereof c~prise6 a cradle 142 slidably ~ted to the ~upport e~8 40 for oveloent between the front ~d -r~r podtio~l~ heretofore de-cribed through the elongated Op~Dg~ 140 in the ~eat ~upport lo~ or leg 70 The cradle 142 i8 po~itloDed bet~ the paced ~tabilirer ar~s 106 of the bridle 88 and ;~pri~e~ a~ ~ub-tantlal U-~haped _ber having a pair of ddrall~ 146, a bottall ~all 1~48 and a trans~rerse pin 150 ~ounted to ani bet~on the ~ld~alls in spaccd relationship to th bottam all ~ The botto~ rall 148~ ha6 depending downwardly ~therefrom~ a pair of tangs ~152 fixedl~ ~ecured to the mounting ~ n~ 125 of the ten8ion control means 20. The leaf spri~g ce tr l portion 134 i8 captured between the tran~ver~e pin lS0 and the cradle botto l ~all 148. The cradle transver6e pin lS0 ~ preferably fitted ~ ith a rubber sleeve 154 and the cradle SUBSTITUTE SHEET

-17- 21,~ 3 bottom ~rall 148 is preferably covered with a rubber ~heet 156 The sleeve 154 and the sheet 156 function to eliminate noi6e other ~ise caused by direct movable engagement of the spring center portion 134 ~ith the cradle 142 during operation of the tension control l eanc and caused by the variable deflection of the ~pring 128 during usage of the chair 10 ~ 8 ~een in Figure 5, the mounting means 125 comprises 8 ~ci~sor echani~m 144 slidably mounted to the support ~ans 40 in substantially flush relationship to a top ~urface 158 thereof and beneath the seat support lo~cr leg 70 The actuating ~eans 127 compri~es an ad~ustment rod 164 rotatabl~r ounted to the support means 40 i8 substantially flush relation~hip to the sa e's top ~urface 58. To thi~ end, the ~upport ~an~ 40 ha~ forl ed in the top surface 158 thereof rear tran~er~c and longitudinal channels 160, 162. The transverse channel 160 i~ po-itioned rcar lardly of the front tran-ver-e cha~ncl 120 a~oclated ~ith the bridle 88 The ad,~u t ent rod 164 is rotatably received within the ~upport ~an~ rear transverse channel 160 at an inner end 172 of the rod, the rod outer end 174 extending laterally out ~ardl~ fro~ the ~upport oleans 40 at chair latcral side 176 oppodtc th hcight ad~u t ~e~nt lever S0 The rod 164 i~ mou~ted ~n rotatablc rcgi~tr,~ ~rith the tra~erse channel 160 by braclcet~ 178 !ecured to the upport leans 40 by an~r suitable ~ch~ical ~an-, ~uch a~ br ~cre~s 180 in regi~trJ ith aligned hole~ (t ~ho~) ill th~ brac~ets and threaded bores (not sho~n) in ,the ~upport ~c~ns. The cissor mechani~m 144 comprise~ a bloctc 166, a pair of plates 168 and a pair of ar l8 170 The bloclc 166 i8 ~lid~blJ receivcd ~rithin the longitudinal channel 162 of the ~upport ~ns 40 and includes a pair of shoes 182 in ~hich the tang~ 152 of the cradle 142 are ecurely received The platcs 168 include threaded portions (not sho~ n) operatively ollgag~g the thrcadcd ad~ust0e~t rod 164 ~ecau~e the plate threaded port~onc (not ~ho~n) and their respecti~re rod threaded SUBSTITUTE SHEET

W O 93/18686 ' ' -18- P ~ /USg2/06~72 ~la3263 portions 184, 186 are oppo~itely directed, rotation of the ad~u t eDt rod ln one direction or the other causes the plate6 to ove toward or a~ay from each other The arm6 170 are pivotall~ ~ounted at front and rear end6 188, 190 thereof to and bet~een tbe plates 168 and the block 166, re~pect~vely In this ~anner, when the ad~ustment rod 164 i6 rotated in one direetion, the plates 168 move to~ard each other eausi~g the sei~80r ar~s 170 to pivot and force the bloek 166 to~ard the rear position of the tension eontrol mean6 20.
Rear~ard o~eDent of the bloek 166 forces the cradle 142 ~nd leaf pring 128 rear~ardly, thereby deerea~ing the effective oo ont ar length bet~een the spring and the force exerted by the oeeupant on the rear portion of the seat support upper leg 68 to inerea~e the pring'~ re-i-tance to defleet~on of the ~- t_and-bac~ ~upport 16 When the rod 164 iB rotated in the oppo~ite direetion, the plate- 168 ro~e a~a~ fro each other eaw ~n~ the ~ci--or an~ 170 to pi~ot and force the block 166 for~ rdl~. For~ard -Knerent of the bloek 166 forees the eradle 142 ~d ~prin~ 128 for~ardl~, thereb~ in,ereasing the effeetive o ont~ r ~l~ngth and thereb~ deerea ing the ~pring's resistance to deflection of the ~oat- nd-bae~ ~upport 16.

~ To~faeilitate anual rotation of the ad~u t~ent rod 164, the~ e 1~ provided on~ the outer end 174 thereof ~ith a h~nd'~nob 1 *.~ The~,hand~bnob 194,~preferabl~ differs in geo~etry fro ~ tb~ ~h i p t,~ad~u~ ~ t ~nob~60~ ~o that the knobs ean be cil~ alff-r~ti-t-d~by~n occupant.~
, ,, ; , .
~ndicated~ above, certain ele~ente of the teneion control n~ 20 are~encIo~ d b~ th ~e-t euppDrt'lo~er leg 'cover~`76 ~nd are thus~prot ct-d from~ dc~Jge and accumulation of ~ ; dw t~ ch-can aff-ct operation~of the teneion control meane.

,~' m, In a eecond ~b~od~ent of the invention, illuetrated -~ln Figure- 12 ~nd 15, the ten-ion control ~eane 20 furtber .: :' :

SUBSTITUTE: SHEET

W O 93/18686 ~ ~ P ~ /US92/06272 -19~ 32~3 co prises a retainer 196 securely mounted to the seat 6upport lo~er leg 70 and having an open rear portion 198 providing access to the interior of the retainer The retainer 196 can be formed integrally ~lth the seat support lower leg 70 or be ~eparate therefro~ but mounted to the seat support by any ~uitable echanical means The stiffening means 18 comprises a ~ub~tantially S-~haped leaf ~pring 200 having an upper curved end 201 freely engaging the seat support upper leg rear part at an apex 202 of the curved end, and a lower substantially ~traight end 204 received ~ithin the retainer 196 tbrough the open rear portion 198 thereof. In this embodiment of the invention, the elements of the tension control means 20 are ~ubstantially identical to those of the above-descr~bed e~bodiment except that in the embodiment of Figure 12, a fulcrum pad 206 i~ unted to the block 166 rather thJn the cradle 142 Li~e the cradle 142, ho~ever, the fulcrum pad 206 is set in ~lldable regi~try ~ith the elongated opening 140 of the ~eat ~upport lo~er leg 70 and includes tang- 152 engaging the ~hoes 182 of the bloc~ 166. The pad 206 is set in lidable engagement ~lth a botto curface 208 of the leaf cpring ~trai8ht end 204 In additlon. li~e the cradle 142, the fulcrum pad 206 is adapted to move bet~ecn the front ~and rear positions heretofore de~crlbed to aIt-r th effective length of the leaf spring and thereb~ ad~u t th ~aue'~ re~i~tance to deflection of the eeat-and-bac~ cupport 16.~ ~pecifically, upon rotation of the at~ w tm~nt rod 164 in ~one directlon, the fulcrum pad 206 moves r r~crdly to ~horton the effective moment ar~ le~gth bet~een the ~pring and oc _ t donn~ rd force and thereby increase the ~pr~ng'~ re~l~tance to relative ~o~n~ard movement of the ~eat ~upport upper leg 68. When the fulcrum pad 206 is moved toward the front po d tion of the~tension control means, the moment arm i~ increa ed, th reby decrea-ing the spring' 8 re~i6tance to d _ rd relative ove eDt of the seat support upper leg 68 Co~eguently, ~hon a relatively li p t occupant uses the chair, the fulcr~ pad 206 i- po~itioned ad~acent the front po~ition of the ten~ion control eans 20 Alternativel~, when a heavy SUBSTITUTE SHEET

W O g3/18686 P ~ ~US92/06272 occupant uses the chair 10, the fulcrum pad 206 i8 positioned clo~er to the rear position of the tension control means 20.

In a third embodiment of the invent~on, illustrated in Figure 13, the stiffening means 20 comprises a substantially ~tr ight leaf ~pring 210 having the lower front end 212 thereof fl~edl~ ~ecured to the ~oat support lower leg front part 214 by an~ uitable echanical eans, such as by a plurality of bolts 216 in regi~try ~ith an equal nu ber of pair~ of aligned hole6 (not ~ho~n) ~xtending through the ~pring front end 212 and the lo~er leg front part 214. ~n upper rear end 220 of the leaf - pring 210 i~ bent along a gradual curve, the apex 222 of which freol~ attingly ~ngages the seat support upper leg rear part 138.

In the t~n~ion control ~eans 20 of the embodiment lllu~trated ~n Figurc 13 the engaging means 123 compriees a cam p d 224 ~ounted bout a hori~ontal axi~ of rotation on a p~n 226 for lrg tho ou~tin~ ean~ 125 and rotatably secured tran~verc~l~ to knd bet~een oppo~ng d dewalls 78 of the seat culpport lo~er leg cover 76. The c _ pad 224 is et in registry ~lth~n ~-nlarged~ op~ning 228 extending through the ~eat support lo~er~ 70 ant~an ~nlarged cb-nn l 229 ~ithin and the support oan~ 40. The cam pad 224 en W es a bottom eurface 230-of the ~- 1 W ~pr~g ~210~-t a~rear par~t 232 of the pad. The cam pad 224 e t~trI~ngular~n~halpe, ~ith the rcar end 232 thereof bei~ ~ larged~relative to a: front end 234 of~ the pad. Due to ~P thi~g o etry,~ rotation of the~8a e in one direction cau~e~ the p~ad! to ove rr r~ rtI~ and ~upn~rdl~and~ to ~engage the spring lo~er front portion 212 to ~a~ greater extent to thereb~ shorten t~ ~efftcti~e~ _ t ar le~ngth~b-t~ en~the ~pring aod the force oxerted~on the~ eat~ by the~occup nt~and thereb~ increase the cpr~ c re~Jtanc-~to defl-ction~ of~ thé~-~at~support upper leg 68~ ~otation of the pad ~224 in~the ~other ;direction moves the for~ rdly and do~n~ rdly to thereby~increase~the ooent arm ~ length-and retuce the ~pring's resi~tance to deflection.

, 1:
SUBSTITUTE SHEET

W O 93/18686 P ~ /US92/06272

2~ 032~3 The actuating means 127 comprises an ad~ustment shaft 26 threadably o~nted to the support means 40 through a vertical threaded bore (not ~ho~n) of the same, and has a lower end 238 extending do~n~ardly from the ~upport mean6 and mount~ng hand~heel 240 and an upper end 242 above the caoting and in abutting engagement ~ith the ca~ pad rear end 232 In operation, rotation of the handwheel 240 in one direction threads the ad~ust ent ~haft 236 upwardly to force the ea~ pad 224 about it~ pivot axis and rearwardly and up~ardly again~t the leaf ~pring lo~er front end 212 The effective length of the leaf pring 210 is thereby decrea-ed to therefore increa-e the pring'~ re~i-tance to deflection of the ~eat ~upport upp r l-g 68 Conver~ely, upon rotation of the h nd~heel 240 in the other direction, the shaft 236 is ad~usted do~n~ardl~ to lo~er the rear portion 232 of the ca~ pad 224 to th reb~ lner aJe the effective length of the ~pring 210 and deer~aJe the ~ e'~ re-l~tanee to defleetion of the upper leg 68 Referring no~ to Figures 1-3 and 7, the chair ~eat 72 ~ an ~nn r ~hell (not sho~n) and an outer structural ~bell (not ~ho~n) d ~ ounted to and abo~e the seat support upper l-g 68 b~ n~ u~tabl- r~ehanical Dean~, ~uch as by a plur d it~ of ~er~ ot~-ho~ registr~ ~ith aligned holes 246--~t~cdi~g~ the~ at outer hell and the eat cupport upp~r l~g~ Th~ h~f- of~;the~eat 72 i~ co pleRentar~ to that of th- o~at ~uFport;~62, but~ nlarged -~it~ re-pect thereto to pro~lde-the nec-~arr co~fort and ~upport to the occupant In addit~on, ~the~ oeat-~front ~ portion 248 i8 rolled over to co fortabl~ ~ te~ n~occup~nt'o legs A cuoh~on 250 iB
ol W to the ~top of the;~-~inn-r~-shell. The inner shell iB
r o~ bl~ ~f-~tened ~b~an~ uitabI- nap -ean~ to the outer hell.~ B~ thl~ _ thod, the ~at- cuohion 250 can be replaced aB
nece~oarr. The ~eat 72 is preferablr ~ade of Zrtel or pol~prop~lene, co po~ition~ ~-~hich provide oo~e degree of fl-xibilltr to the ~eat during flex of the 6eat-and-back ~upport 16.

SUBSTITUTE SHEET

WO 93/18686 PCr/l~S92/06272 2 ' ~3263 ~ 8 illustrated in Figures 1-3 the chair back 74 i8 substantiallJ half oval in shape and ba8 an enlarged U-6hsped channel 252 ~ ithln a central relief portion 254 formed on a rear surface 256 of the back The back 74 compri~es an inner and an outer ~hell (not ~ho~n), the outer shell being ~ecurely fa6tened to the back ~upport 66, with the sa~e received within the channel 252 and flu~h ~ ith respect to the relief portion 254 by anJ uitable ~ech~nical leans, ~uch as by a plurality of screw6 (not ~ho ~n) extending through aligned orifices (not 6hown) in the baclc and the back support Like the chair seat 72, the back 74 i- preferablJ made of a material such a6 Zytel or polypropJlene to provide fleYibility of the back The chair baclc 74 is enlarged with respect to tbe back support and in thi6 ~er fl~nction~ to distribute the weight transferred from the occupant to the chair ~eat and back ~upport a~ the occupant lean~ rear /artl~ in the a~ between the upright and full tilt po~itioo~. A cu hion 262 i- ~olded to the inner hell, the sa~e be~g re~rabl~ fa~tened bJ any uitable ~nap oeans to the outer chell. B~ thi~ ~ethod, the baclc cu hion 262 can be replaced as necec~arr ~ illu~trated in Figure~ 1-3, the chair can be pro~rlted ~Ith pair of optional r~re~ts 264 ~ounted on oppodt- lateral cides 56, 176 of the chair 10 Specifically, ch ~ t~ 264 is a ~ubstaltiall~r V-~haped flexible ~ber h ~g, ~th~ referonce to the ~orlc inten-ive pos~tion of the ~eat-and-bac1c ~upport 16, a ~ub~tantiall~ hori~ontal leg 266 and a ~di~goual l~g 268, free end- ~f the hori~ontal and diagonal leg~ bei~8 rotatabl~r ul~ted to the bac~ 74 -and the seat 72, re~pecti~rely,~ at a lateral ide 56 or 176 of the chair The horirontal leg~ 266 provide~ ~upport for an occupant's arm In thi~ _o~r, a- the ~eat-and-back upport 56 flexe~ dom~ardly and b~ ardl~ in re-pon-e to a hift in an occupant'6 ~eight, the r~re~t~ 264 lilc~ise flex thereby acco~odating the chulging geo~etr~r of the s-at-and-back ~upQort Flex of the SUBSTITUTE SHEET

W O 93/18686 P~r/US92/06272 -23- 21~3253 V-shaped arrrests generally occurs at the vertices 270 of the V8~ due to the rotatable connection bet~een the armrest~ and the ~eat 72 and back 74 Each armre6t 264 iB cub~t~ntially rectangular, in cro~ section, with the thicknes~ thereof taperin~ ~ub~tantially at the vertex 270 of the V A reduction of thic~ne~ at the vertex facilitate6 the resiliency of the arDrest 264 ~ ctated above, the armrest~ 264 are rotatably ounted to the chair back 74 and the chair sest 72 at lateral ~ide~ 56, 176 of the chair 10 To this end, the free ends 272, 274 of the horirontal and diagonal legs 266, 268, re~pectively, ha~e for~ed theroon sockets 276 In addition, an attachment eans 278 i8 provided for ~ounting the armrest6 264 to the seat 72 and the bac~ 74 ~ b~t ~een in Figure 14, the armrest attachment mean~ 278 co pri-e- a pair of U- haped brac~et6 280, each having a ~ b portion 282 and a pair of side portion~ 284 Each d de portion 284 include~ a bole 286 ext~ding therethrough One brac~et 280 i~ ecurel~ ounted to and bet~een the chair back ~hell~,-~ith the ~eb portion 282 ~andwiched tberebet~een and the d de portion~284 ~xtendlng r- rv rdly of the chair A recoss ~n tbe inner chair bac~ ~hell (not ~ho~n) accommodates the brac}-t ~eb. Tbe other ~brac~et ~280 i8 mountod to and bet~een tbe ehair~ ~eat hell~, the -~eb - portion 282 ~and~iched therebet~cca~and the ~ide portlons 284 extending do~n~ardly from the cbair ~eat 72. A~r ee~ ~n~the inner chair seat shell (not ~ho~n) acco odates the brac~et ~eb.

The att-eho~nt ;_ an~ 278~ further comprise~ a hollo~
tubular spaeer 288 partially~reeei~ed within each aDmre~t socket 276,~the paeer being aligned wlth ~a respective hole 286 in the U-~haped brae~ t 280 Bolt~ ~-290 eYtend thr ugh the al~gned ~oe~ t~ 276, ~paeers 288 and hole- 286 to seeurely ount the arrre~t 264 to the braeket8 280. ~emispherieal protect~ve cap~
292 ean be placed over the bolts 290 ~:~ I~CTITI ITF CI~FFT

W O 93/18686 P ~ /US92/06272 -24- !

stated above, the chair 10 compriees the first ~tabili~er ~eans or bridle 88 pivotally unted to and between the upper and lo~er leg portions 68, 70 of the eeat support 62 for provlding stability to the same during deflection of the upper leg 68 relati~c to the lower leg by virtue of the rc~ilient fir-t blght portion 69 intermediate the sa~e In a i ilar ~anncr, the armrests 264 also function a~ tab~lizor ~ean~ for the seat and back support 16, but not ~lth re~pect to the upper and lower legs 68, 70 thereof.
Rather, by virtue of the pivotal connection of the armrests 264 to and bet~een the eat 70 and the back 74, on opposite lateral ~ides 56, 76 of the chair, the armrests provide lateral ~t-bilit~ to the ~eat and back upport 16 bet~een the upper leg portion 68 and the upper back ~upport portion 75 during relative dd lcctlo~ thereof b~ ~irtue of the reailient second bight portion 73.

No~ rcfcrri~g to Figurcs 16 and 17, the secont e bod~ ~nt of cbair 310 of the pre~ent invention includes chair ba~e~-312, ~ ~tal 314, unita q chair ~upport rember 316, spine ~upport J~d ad~u t e~t a~ 318, ar~s 321,~ seat back 322 and ~eat~bottoo 324.
: -No~ ref-rr~ng~ to Figure 18, pine ~upport ~na ad~u~t ~ ~acoe~bly~318~ co~pri~ed of upper aupport casting 328 d lo~er cpport ca-tiog 330. Upper ~upport~ca~ting 328 i~
~doptcd to cl _ ingly ~engagc lo~r ~upport casti~g 330 thereby cl~ping tongue portion 334 of unita~y cbair~support member 316 -~ th~rdb~t~o~n.~ It i~ i portant ~to note that the cooperation of ~upp-r~ca tiDg~328 and~lo~er~ca~ting 330~-ct to drimpingl~ enga8e toogu- port~on;~334 of~-upport~ ember~316 -long its outer peri ~ rr. Tku~,~ ton~De~ portion 334 is fird y retained within a~-rbl~ 318 ~thout -pl~cing bolts or tbe li~e through one or or~ perture~ ~n tongue 334. It ~a8 found that ~hen tongue 334 :~ :

SU~STITUTE SHEET

W O 93/18686 P ~ /~S92/06272 -25- 210~32~3 ~as fastened to casting 318 via bolting or the like, the 6tre66 as~ociated ~ith u~ing such conventional fa~tening technique6 causcd prcmature failure in tongue portion 334 However, it ha6 been found that by clampingly en8aging tongue 334 about it6 outer perlphery, stress failures of tongue 334 are greatly minimired Control mechanism assembly 336 i8 adapted to be hou~ed ~ithin ~ell 344 of lo~er ~upport casting 330 Control echani-m a~sembly 336 is adapted to move C-shaped spring 326 thereby effecting the stiffness of chair 310 Thi~ function ~ill be ore fully di~cu~sed hercinafter Arm strap 338 i~ pivotally connected to preten6ion bar 332 bJ ~ay of pin 346 rretension bar 332 is pivotal about bu~hing~ 348 Bu~hings 348 flt ~ithin their respective ~ells 350 ~lthln lo~er ~upport ca~ti~g 330 Bu~hings 348 permit preten d on bar 332 to pl~ot within lowcr Jupport casting 330 Pret~n d on bar ~pring~ 333 ~it ~ithin lo~er casting 330 and urge agalD~t thelr re~pectively ~ociated bushings 348 It is important to note that arm6 321 are not rl~idly fa-tened to lo~er ca~ting as~embly 330 but are attached th~r~to by ~ay of pretension bar 332 Because pretension bar 33`2 1~ ~ _ t re-ilient, it acts li~e a torsion bar and offers - li it-d~d gree of donn~ rd c-r~ent 339 to ar s 321 (such as ~hen a u er is leaning again~t one ~of the~ arms 321). This abil~ty of arms 321~to offer li ited ~degree of movement aids inithe co~forjt of the user e-pecially ~hen the u~er i~ leaning over~ o~e of the aD 8 of thc chair. This is to be contrasted ~ith~ ~ell ~no~n techniques of rigidly unting arms 321 to a ~olid part of a chair ~ba-e ~uch that they offer no relative c~ t bet~ecn the s-l~e~ and th ~b e. The limited movement of armJ 321 in thi- anner i~ lar~ely due to thc resiliency of pret n~ion bar 332 and lts ability to act a~ a torsion bar :~

_..QCT~TuTE SHEET

W O 93/18686 P ~ /US92/06272 2103~63 Stiffness ad~ustment lever 340 is used to adju6t the stiffness of seat bottom 324 (seat bottom 324 not ~hown in Figure 18) ~eight ad~ustment lever 342 iB u6ed to ad~u6t the hcight of seat bottom 324 of chair 310 Thi~ height adjus~ment function has been di~cusset in conjunction with chair 10 and will not be repeated here No~ referring to Figures 19 and 20, arm6 321 are attached along their lo~er portion 350 to ends 352 of arm 6trap 338. Preferably, upper end 354 is not attached to seat back 322 thereb~ allowing seat bac~ 322 to freely move ~ithin the confines establi~hed by unitary cha~r support member 316 In lts preferred embodiment, arm6 321 matlngly engage end~ 352 such that the~ may be easily installed or replaced in the field Thl~ allo~- the custorer to save initial cost~ by purchasing the chalrs without the arms and then, at a later ti~e, purchasing the an~ to upgrade the loo~ and style of the chair Addltlonally, replaclng do aged arms is ~imple under this ccb~ e. ~nd~ 352 are nor~ally hidde~ fro~ vlew by chair covering 356 Accordingl~, when chair 310 is used without ar~s 321, ends 352 are inconspicuous At the ti e arms 321 are added to chair 310, cba~r covering 356 is simply pushed out of the way thereb~ ma~ing ends 3S2 available for engaging lower portion 350 of anrs 321 Alternativel~, chair covering 356 can be designed ~ith a br a~ awa~ portion which is easily removed from the portlon of chalr covering 356 ~hich o~erlays ends 352 No~ reforring to Figures 21-23, a~ wa~ briefly lntroduced earller, the tension ad~ustment for seat bottom 324 i8 provlded b~ the ove e~t 358 of C-shaped spring 326 ~hen ~prlng 326 -1~ its left most position, seat bottom 324 will offor a ~i um resistance again~t downward reflection 360 When ~prlng 326 is ~oved to it~ right most location 326' it ~ill offer tbe lea-t re~l~tance against downward reflection 360 Tbe left to right ove~ent 358 of C-shaped spring 326 i6 acco~pli~hed by the rotation of tension adjust ent le~er 340 c~RSTlTUTE SHEE~

W O 93/18686 P ~ /USg2/06272 ~ -27- 21~32S3 When tension ad~ustment lever 340 i6 rotated, first gear 362 rotatingly engage6 eecond gear 364, which in turn rotate~ lag screw 366 Lag screw 366 i8 threadingly engaged to lag screw finger 368 Lag crew finger 368 extends up~ardly from well 344 and engages lo~er spring guide 370 Lower spring guide 370 claopingly eurrounds and engages lower end 372 of C-shaped epring 326 Upper end 374 of C--haped ~pr~ng 326 terminates lnto upper ~pring guide 376 As lever 340 i8 rotated, finger 368 ~o~es along direction 358 Because finger 368 engages lower ~pring guide 370, ~pring 326 follows the mo~ement of finger 368 Upper ~pring gulde 376 is preferably notched 378 (see Figure 2l~) 8uch that notch 378 po8itively engages raised portion 380 of unitary chair support member 316 The cooperation between notch 378 and raieed portion 380 maintains upper portion 374 of C-shaped spring 326 in its proper po d tion Li~ewi-e, lo~er epring guide 370 includes opening 382 to po~ltiw l~ engagc finger 368 therebr preventing lower porti 372 of C-chaped ~pring 326 fro di8lodging. It i8 important to noto th~t becau e the contour of C-shaped epring 326 clo~ely atche~ the contour of bite portlon 384 of unitary chair support n~b~r 316, C-~haped spring 326 is accorded a 8reater degree of nove ect 358 than that ~hieh ~ould other~ise be possible by u i~g th leaf ~prin~ e~bodioente et out in Figures 8, 12, and 13. ~ccordingly, the C- haped pring 326~ of Figure 21 is the prcf-rr d _ tric hape. Pr-ferabl~, the C-shaped spring i6 e ~ fro la~inated ~aterial, preferably unidirectional flb~rgl ~ eoated ~ltb epory~r-sin In a prototype of C-shaped cpr~g, ~evCn làyer- of -unidirectional flberglass ~ere coated ~itb epo~ re d n and bonded together using heat and pressure to fon the la inated ~aterial into the desired C-shape Preferably, thc o~tsite-surface of the C-shaped spring i8 coated ~ith an ultr -blgh ~olec~ular ~ ight polyeth~lene (UHMWPE) No~ referring to Figures 24-26, unitary chair ~upport ~e bér 316 co~priee~ an elongated epine portion 386 hàvlng a fir~t cnd (or tongue) 388 and a second end 390 which SUBSTITUTE SHEET

blend~ into a seat back pan 392 Tongue 388 i6 adapted to be eDclampingly engaged between upper support casting 328 and lower support cast~ng 330 as ha6 already been di6cu66ed Elongated spine 386 lncludes seat bottom pan 394 Seat back pan 392 and seat bottom 394 are both integrally molded with elongated spine 386 Thi~ process of integrally forming pan6 392, 394 and spine 386 re~ult in a unitary chair support member 316 which i8 ~xtromelr strong and eliminates assembly costs sssociated with the chair of Figure 1 Seat bottom pan 394 i8 preferably located along elongated spine 386 between seat back pan 392 and tongue 388 8eat bottom pan 394 preferably includes a seating ~urface 396 adapted to ~upport a w er snd is defined by an outer peripheral edge 398 Seat bottom pan 394 also includes first and second relieved portions 400, 402 Relieved portions 400, 402 are respecti~ely di~placed 404, 406 from perlpheral edge 398 of ~oat ~ottom pan 394 and elongated spine 386 is ~oined with the ~oat boteo p~n 394 proximate relieved portions 400, 402 and di-tal peripheral edge 398 By ~oining elonga~ed spine 386 to ~o-t botto p n 394 dl-tal peripheral edge 398, portion6 of seat bottoo pan 394 lying ~ithin displacement 404, 406 form resilient ~upport ~urface- for fullr ~upporting the legs (406) and the tail bone area (404) of the u er It is ,aleo i~portant to contrast the second bodi~nt of elongated pine 386 a6 i~ ~eon in Figure~ 24-26 ~ith tbe flrct ~ bo~di ~nt a ~et forth in Figure 4 As is ~een ln Figure 4, as the ~éat user leans rear~ardly the seat pan i6 neco~arily pulled do~n becau e bac~ support 66 is attached to the outor peripher~ of the ~eat pan In cQntrast, however, when a u er loan~ rear~ardl~ in a chair which employs the elongated ~pine ~t forth in Figure~ 24-26, it does not ha~e as great a effect to pull seat bottom pan do~ rdly as does that seen in the e bodieent of Figure 4 bocause spine 386 is not attached to the outer~ periphery of -eat bottom pan 394 Th w , ~hen a chair utlIlros the elongated spine set forth in Figures 24-26, much ore 8upport is given to the user (especially in the tail bone SUBSTITUTE SHEET

WO 93/18686 ~ ~ $ PCI/US92/06272 29- 2 1 ~v`2~

area of tho user) than that which 18 possible in the embodiments set out in Figure 4 Now referring to Figures 27-30, seat bottom pan 394 is eonstrueted having first relief portion 400 and second rei~ef portion 402 Cro~s-seetional vie~ of seat bottom pan 394 are ~ho~D in Flgures 28-30 eaeh talcen at a eeparate loeation along eat bottom pan 394. Raised portion 380 is shown in Figure 29 Ral~ed potlon 380 funetion~ to guide upper spring guide 376 80 as to retaln C-shaped sprlng 326 in its proper location No~ referring to Figures 31-33, aecond end 390 of elongated spine 386 terminates into seat baek pan 392 Seat baelc pan 392 incorporates rel~eved portions 408 to acco, ~odste fl~ing of ~eat back pan 392. Retaining fa~teners 410 are f teDed to, or preferably integrally molded ~ith, seat back pan 39i. The u e of retaiDlDg fa~teners 410 ~ill no r be explal~ed iD eon~unetloD 1th Fi6ures 34-36.

No~r referri,ng to Figures 34-36, in its preferred e bo~i~ent, the ~eat baelc pan 392 and the seat bottom pan 394 of tbe ~at~to the pre~ent inVeDtion is eovered ith a soft pliable fo 412 ~rhieh i~ in turn eovered by a fabric Although foam 412 ~d~fabrie 414 ean be direetlr affixed to eat back pan 392, in;~ lt~ proferred ~bodi ent foa1- 412 and fabric 414 are fir6t f-~t~;t~to ~t bae1~ inDer ~hell 416. Seat baek inner shell 416 l~lcorp~r tes apertures 418~ ~hieh eooperative a gage and f ,ton~to ~retaining fa, tener~ 410 By using sueh a seat back ~,er~eh 11 416 arrangement, variou~ fabric texture6 and colors ean be pr~-~bled ollto shells 416 Thi8 offer8 great fl~cibilit~ ~i: ~eeting high volu~e d 8 ~hile lo~ering the ~tor~ e'o-ts associated ~itb keeping complete chair a-~blies~ i~ stoe,lc for eaeh fabrie color Finger~ 420 are 'inte~rall~ ~formed ~ith s-at baek inner hell 416 ~fter foam 412 Jnd fJbric 414 iB fastened to ~eat b-ek inner shell 416, flnger~ 420 are folded do~n~ardly before the assembly i6 SUBSTITUTE SHEET

W O 93/18686 P ~ /US92/06272 ~1~3?~S3 attached to ~eat back pan 392 When folded down in this manner, fingers 420 cover any fabric ends, glue, fasteners, or other unattractive feature6 ~hich might otherwise be visible through the openings made by relieved portions 408 No~ referring to Figure 21, in the ~ame way that ~eat back inn~r ~bell 416 facllitated adding foam 412 and fabr~c 414 to seat bac~ pan 392, seat bottom inner shell 422 can be u~ed to add foam 412 and fabric 414 to ~eat bottom pan 394 In it~ preferred embodiment, seat bottom lnner ~hell 422 is adapted ~ith engaging lip 424 to positively attach seat bottom inner ~hell 422 to ~eat bottom pan 394 by ~ay of fir6t and 6econd relief portion6 400, 402 While the invention has been described in connection ~ith ~everal preferred e~botluent~, it ~ill be under~tood that I
do not int~d to li it the invention to the~e embodiments To tbe contrar~, I intend to cover all alternative modification6 and equivalent- as ra~ be ~ncl~ded ~ithin the ~pirit and ~cope of the ~nv~ntion as defined by the appended claim6 I

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Claims (20)

-31- I claim

1. A unitary chair support member, comprising an elongated spine portion having first and second ends, said first end adapted to be supported by a chair base, said spine including a seat bottom pan and a seat back pan, said pans integrally molded with said spine thereby forming said unitary chair support member, said seat back pan located at said second end of said spine, said seat bottom pan located along said spine between said seat back pan and said first end of said spleen, said seat bottom pan including a seating surface adapted to support a user, said seating surface defined by an outer peripheral edge and including first and second relieved portions displaced from said peripheral edge of said seat bottom pan, said spine joined with said seat bottom pan proximate said relieved portions and distal said peripheral edge of said seat bottom pan, said portions of said seat bottom pan lying between said first and second relieved portions and said peripheral edge forming resilient support surfaces for fully supporting the legs and the tail bone area of the user.

2. The chair support of claim l wherein, said chair support member is an integral member formed using an injection molded process.

3. The chair support member of claim 2, wherein said member is molded from glass reinforced polyester.

4. The chair support of claim 2, wherein said member is molded from glass reinforced nylon.

5. The chair support member of claim 1, wherein said chair base supports and is secured to said first end of said elongated spine by clampingly engaging said elongated spine along the outer periphery of said first end of said spine.

6. The chair support member of claim 1, wherein said first and second relieved portions of the seat bottom pan form means for retaining an inner shell member.

AMENDED CLAIMS
[received by the International Bureau on 8 February 1993 (08.02.93);
new claims 7-20 added;
other claims unchanged (4 pages)]

7. (New) A one piece chair support member, comprising:
a seat back pan portion;
a seat bottom pan portion;
a first narrow spine portion connecting said broad seat back and bottom pans, wherein said seat bottom pan is adapted to be supported by a chair base, and wherein said seat bottom pan includes a first relieved portion spaced apart from a peripheral boundry of said seat bottom pan, said first relieved portion defined by a first surface proximate a center of said seat bottom pan and a second surface distal said center of said seat bottom pan, wherein said first narrow spine portion is attached to said seat bottom pan proximate said first surface of said first relieved portion.

8. (New) The member of claim 7, further including a second narrow spine portion connecting said seat bottom pan to said chair base.

9. (New) The member of claim 8, wherein said seat bottom pan includes a second relieved portion spaced apart from said first relieved portion and said peripheral boundry of said seat bottom pan, said second relived portion defined by a first surface proximate said center of said seat bottom pan and a second surface distal said center of said seat bottom pan, wherein said second narrow spine portion is attached to said seat bottom pan proximate said first surface of said second relieved portion.

10. (New) A tension adjustment spring for use with a chair of the type having a base and a spine supported by said base, said spine including a seat bottom support portion, a base engaging portion, and a c-shaped bite portion intermediate said seat bottom support portion and said base engaging portion, said spring comprising:
a c-shaped body portion adapted to nest within said c-shaped bit portion of said spine, means for moving said c-shaped body portion within said c-shaped bite portion thereby providing for adjustment of the tension of said chair.

11. (New)The spring of claim 10, wherein said c-shaped body portion is comprised of laminated material.

12. (New) The spring of claim 11, wherein said laminated material comprises unidirectional fibre glass and epoxy resin.

13. (New) The spring of claim 12, wherein said laminated material is formed into said c-shaped body portion heated and pressurized until said epoxy cures.

14. (New) The spring of claim 10, wherein said c-shaped body portion is coated with an ultra-high molecular weight polyethylene.

15. (New) The spring of claim 10, wherein said moving means includes a lag screw, and an engaging finger threadedly attached to said lag screw.

16. (New) A chair support structure comprising:
a spine portion adapted to support the weight of a chair user, said spine portion terminating in a tongue, said tongue having an outer periphery, a chair base adapted to clampingly engage said tongue about its outer periphery.

17. (New) The chair support structure of claim 16, wherein said base comprises upper and lower separable halves, said halves adapted to matingly engage said tongue therebetween along said periphery of said tongue.

18. (New) An arm support structure for a chair, said chair of the type including a base for supporting the weight of a user of said chair, comprising:
an arm strap, and first and second arm rests, said arm strap supporting said first and second arm rests, a pretension bar connected between said arm strap and said base, wherein said pretension bar is generally resilient, thereby allowing said first and second arm rests to move downwardly relative to said base.

189. (New) The arm support structure of claim 18, wherein said first and second arm rests are detachable from said arm strap.

20. (New) A chair comprising:
a base, a spine supported by said base, said spine including a seat bottom support portion, a base engaging portion, and a c-shaped bite portion intermediate said seat bottom support portion and said base engaging portion, a tension adjustment spring having a c-shaped body adapted to nest within said c-shaped bite portion of said spine, means for moving said c-shaped portion within said c-shaped bite portion, thereby providing for adjustment of the tension of said chair, wherein said base is adapted to clampingly engage said base engaging portion of said spine along an outer periphery thereof, an arm strap, and first and second arm rests, said arm strap supporting said first and second arm rests, a pretension bar connected between said arm strap and said base, wherein said pretension bar is generally resilient, thereby allowing said first and second arm rests to move downwardly relative to said base.