Control for seating unit with back stop

A seating unit includes a base with a control housing, a back supported on the base for reclining movement, and a seat supported at least partially by a pivoting link on the base for synchronous movement with the back upon recline of the back. A back stop is operably mounted on a pair of parallel guide rods that extend transversely across the control housing for selective movement to a plurality of different positions where the back stop engages the link to limit movement of the seat and hence limit recline of the back to a plurality of selectable recline positions corresponding to the plurality of different positions.

BACKGROUND

The present invention relates to seating units having a seat support and back coupled to a base for synchronous movement and having an underseat control for controlling movement of the back to recline positions.

Synchrotilt chairs provide a seat that moves simultaneously with recline of its back, such as to reduce “shirt pull” upon recline, to improve comfort, and to promote healthier support when performing tasks while seated for extended periods of time. In one type of synchrotilt chair, the seat moves forward upon recline of its back, so that a seated user's hands stay relatively stationary whether the back is in the upright or reclined position. This is not easily accomplished, since it requires a mechanism that creates stable and smooth forward movement of the seat during rearward recline of the back. Also, it is desirable to reduce cost, weight, and assembly time, and to accomplish this with simplified components. At the same time, the competitive furniture market requires high quality and durability. There are many conflicting and challenging design requirements, such as the desire for small package size, while maintaining an attractive appearance, an environmental “green” friendliness (including the ability to separate components into recyclable parts without substantial effort), and a desire for design flexibility, relatively few components, and mechanically-efficient arrangements that are durable, long-lasting, robust, and easily assembled.

It is known to limit rearward recline of a back through use of a pivoting cam. (See cam/back-stop mechanism 36 in FIG. 8 of Bedford U.S. Pat. No. 5,871,258.) However, it is desirable to provide alternative motions and parts to meet packaging requirements and functional requirements of the present chair design with novel biasing springs. Also, improvements are desired to increase design flexibility, simplify components, reduce parts and pieces, make them lower in weight and cost, improve assembly and reduce manual labor during assembly, and to make the assembly more durable and robust.

Thus, a system having the aforementioned advantages and solving the aforementioned problems is desired.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, a seating unit includes a base with a control housing and a guide extending across the control housing. A seat is supported on the base and a back is supported on the base for reclining movement. A back stop is slidably mounted on the guide for selective translational movement to a plurality of different positions where the back stop limits recline of at least the back to a plurality of selectable recline positions corresponding to the plurality of different positions.

In another aspect of the present invention, a seating unit includes a base with a control housing, a back supported on the base for reclining movement, and a seat connected by a pivoting link to the base for synchronous movement with the back upon recline of the back. A back stop is operably mounted on the control housing for selective movement to a plurality of different positions where the back stop engages the link to limit movement of the seat and hence limit recline of the back to a plurality of selectable recline positions corresponding to the plurality of different positions.

In yet another aspect of the present invention, a seating unit includes a base with a control housing and at least one flexible support extending laterally on each side of the housing, the at least one flexible support including ends configured to flexibly move in forward and rearward directions. A back and a seat are supported on the base for synchronous movement upon recline of the back, at least one of the back and seat being supported by the ends of the at least one flexible support. A back stop is operably mounted on the control housing for selective movement to a plurality of different positions where the back stop limits movement of the seat and hence limits recline of the back to a plurality of selectable recline positions corresponding to the plurality of different positions.

In still another aspect of the present invention, an improvement is provided for a seating unit having a control housing and a back supported on the control housing for reclining movement along a first direction. The improvement includes at least one laterally-extending guide in the control housing and a back stop slidably mounted on the guide for translational movement between different back stopping positions.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A seating unit20(FIG. 1) includes a base21, a back22and seat23operably supported on the base21for synchronous movement between upright and reclined positions. The seat23is operably supported by a U-shaped seat-supporting structure36that provides a multi-point stable support arrangement for the seat23on the base21, with the seat-supporting structure36being a relatively simple yet very effective structural component that offers reduced weight, reduced cost, compact size, and robust support for the seat23.

The base21includes a spider-legged arrangement with castors, and a height-adjustable post. The base21(FIG. 3) includes a housing31fixed atop the post and support arms32extending laterally and upwardly on each side of the housing31. The back22includes an arched U-shaped back frame33with lower end sections (i.e. arms34) pivoted to the stationary support arms32on each side. A slide member35slidably engages the housing31. A seat-supporting structure36includes a crossbar37pivotally attached to the slide member35at a first pivot location38and side frame sections39that extend rearwardly from ends of the crossbar37. The ends of the side frame sections39are pivotally attached to the lower arms34of the back frame33at a second pivot location40spaced horizontally from the first pivot location38. The sliding pivot location38and the second pivot location40define a multi-point stable support for a seat23above the housing31. A spring41(FIG. 7) is operably coupled to the slide member35to bias the back frame33and seat-supporting structure36toward their respective upright positions.

The back22(FIG. 1) includes a back shell43supported on the back frame33at top and bottom pivot locations44and45. The back shell43includes a lumbar region46that is flexible for comfortably supporting a seated user, and further includes a spring47biasing the back shell43toward a forwardly protruding shape. The present description is sufficient for an understanding of the present invention, but if additional detail is desired, it can be found in Battey U.S. Pat. No. 5,871,258 which discloses additional detail of a back arrangement similar to the back22. The entire contents of Battey U.S. Pat. No. 5,871,258 are incorporated herein in their entirety by reference.

The housing31(FIG. 4) is supported on the base21, and includes sidewalls50providing a recess into which a biasing device (i.e. coil spring41) is positioned. An L-shaped torque arm52(FIG. 7) is also operably positioned in the recess and includes a first leg53engaging an end of the spring41, and a second leg54. A back surface of the first leg53defines a row of teeth55. A half-disk-shaped support56is supported by a pivot pin57, and includes an arcuate row of teeth58that mate with the teeth55to pivotally support the torque arm52with a non-slip configuration. The second leg54has an end attached to a link59that is in turn connected to the slide member35. The slide member35includes bearings61that slidably engage the housing31, such as by slidably engaging the top edges of the sidewalls50. As will be understood below, when a seated user reclines the back22, the slide member35is moved forward by arms34, causing the L-shaped torque arm52(FIG. 7) to pivot on arcuate support56, thus compressing the spring41. This provides a resistance to recline of the back22, since the seat23is connected to the back frame33, as described above. Notably, the half-disk-shaped support56is rotatably adjustable to adjust a length of the torque arm defined by the first leg53, thus providing an easily operated spring tension adjustment mechanism. The above discussion of the biasing device and system and system operation are sufficient for an understanding of the present invention, but it is noted that they are described in detail in Battey U.S. Pat. No. 5,871,258, which was incorporated by reference above.

The seat-supporting structure36(FIG. 4) includes the crossbar37and side frame sections39rigidly fixed to the crossbar37and extending rearwardly. The illustrated side frame sections39extend only rearwardly, but it is contemplated that the side frame sections39could extend forwardly (see the embodiment ofFIG. 15, with crossbar37A and side frame members39A). Alternatively, it is contemplated that the side frame members could extend both forwardly and rearwardly, and/or could form part of a perimeter frame supporting a seat and that is supported by the crossbar above a base and control housing. The crossbar37has a lower center section with a pair of apertured down tabs63. A mounting block64is attached to a top of the slide member35, and fits between the down tabs63where it is pivotally secured to the down tabs63by a pivot pin65(FIG. 4). It is contemplated that a variety of other pivot arrangements can also be constructed that will work in the present invention.

The side frame sections39(FIG. 4) have protrusions66that extend outwardly from tail ends of the frame section39into pivotal engagement with mating structures on the support arms34of the back22. The protrusions66are located horizontally rearwardly of the mounting block64and pivot pin65, to thus provide a non-aligned multi-point support system for the seat-supporting structure36. The mounting system provides a three point support where the mounting block64is relatively narrow, but it is noted that where the mounting block64is elongated, it might be considered a four point support arrangement. The points of support preferably should be horizontally spaced apart sufficiently to provide a stable seat support structure. It is contemplated that a horizontal spacing in a fore-aft direction of about6inches will provide sufficient stability. However, this dimension will change depending upon the structural stiffness and rigidity of the base21, especially housing31, cross bar37, the seat23, and other structural components of the chair20.

One of the side frame sections39(FIG. 4A) comprises a beam defining a flat horizontal bearing flange67and bearing cap68, and the other of the side frame sections39′ (FIG. 4B) comprises a beam defining an L-shaped horizontal bearing flange67′ and bearing cap68′. The seat23includes a perimeter frame69with side frame members70and70′ (FIG. 3) attached to each respective side. The side frame member70is shaped to mateably and slidably engage the bearing flange67and bearing cap68(FIG. 4A) and the side frame member70′ is shaped to mateably and slidably engage the bearing flange67′ and bearing cap68′ (FIG. 4B). Notably, the bearings67,67′,68, and68′ slidably support the seat23for fore-aft movement during seat depth adjustment, while the up flange67″ on bearing flange67′ serves to guide the seat23as it moves in a fore-aft direction without binding. Notably, the up flange67″ forms a guide that is very resistant to the seat becoming skewed and bound up. This is due to the length to width ratio of the bearing67′. It is contemplated that the present invention can be used with or without having a seat depth adjustment feature on the chair.

It is contemplated that the present inventive crossbar arrangement can be used with a wide variety of different seats. Nonetheless, the present illustrated seat is particularly comfortable, environmentally “green” friendly, and desirable for many reasons. Notably, a seat not unlike the illustrated seat is described in detail in pending application Ser. No. 10/792,309 which was incorporated by reference above.

The illustrated seat23(FIG. 10) includes a front portion75and a rear portion76extending forward from the rear portion75. It is noted that the front and rear portions75and76are particularly constructed to provide comfortable seating, while also being constructed to meet the difficult functional requirements of a seat. The difficult functional requirements for seats come from both use and abuse conditions. In “normal” use, a seated user will position themselves fully onto the seat, with their pelvis at a rear of the seat. However, seated users also often slouch (i.e. the seated user is leaning against the back22, but their pelvis is near a front edge of the seat23) or perch (i.e. the seated user is sitting upright, but his/her pelvis and full weight is near a front edge of the seat23). Also, users sometimes abuse chairs by trying to stand on the seat. While this is strongly recommended against, it still is a condition that a chair may be subjected to and for which there are seating standards proposed by the Business and Furniture Industry Manufacturers Association (BIFMA), a trade association. When a person stands on a seat, substantial pressure is applied at whatever location they stand on, which may be in the front portion75or rear portion76.

The illustrated rear portion76(FIG. 3) includes the perimeter frame69and defines an opening81. The perimeter frame69(FIG. 10A) is attached to the frame members70and a top cover82′ attached such as by screws or other known fasteners. The side frame members70integrally form the seat-depth-adjustment structure by the bearing arrangement shown inFIGS. 4A and 4B. Notches (not specifically shown) can be formed along the side frame members70and a seat depth latch can be operable positioned on the perimeter frame69for selectively engaging the notches to hold a selected seat depth adjusted position. (See the application Ser. No. 10/792,309, previously incorporated by reference.) Alternatively, a fixed attachment is used if seat depth adjustment is not desired. Notably, the illustrated perimeter frame69is surprisingly flexible and twistable in a direction perpendicular to the top seating surface when it is not attached to the seat-supporting structure36, for reasons described below. Nonetheless, the seat-supporting structure36adds considerable strength against twisting-type flexure of the seat. The illustrated side frame members70define a series of pockets83and curved chute-like bearing surfaces84. Resilient spring wire supports85have linear sections86that extend across the opening81, and have L-shaped ends87that extend downwardly into the pockets83. In an unstressed condition (FIG. 1B), the L-shaped ends87are near or abut an outboard end of the pockets83. When a seated user rests on the linear sections86of the wire supports85, the ends87are drawn toward each other. Notably, the pockets83permit inward movement of the ends87without inwardly stressing the opposing sides of the perimeter frame69. (Notably, if the inward movement of the ends87were immediately resisted by the perimeter frame69, there would be incredible pressure on the perimeter frame69, due to the mechanical advantage caused by drawing the ends inward as a straight wire is bent in its middle area.) Because of the reduced strength requirement in the perimeter frame69, its cross-sectional size can be reduced from chairs where a tensioned fabric is stretched across an opening in a seat frame.

The surfaces (FIG. 10C) on the inboard end of the pockets83acts as a limit to inward movement of the L-shaped ends87in the event of substantial weight on one or more individual wire supports85(such as if a person stands on the seat23). Notably, surfaces on the outboard ends of the pockets83can, if desired, be foreshortened and used to abut the L-shaped ends87to provide a pre-form or pre-stressed condition in the wire supports85. Also, the wire supports85can be pre-bent to a desired non-linear shape if desired for spanning across the opening81. The illustrated wire supports85are individual, spring metal and round in cross section, but it is contemplated that they can be loop-shaped or serpentine in shape or other shape, can have a flattened or other cross-sectional shape, and can be metal, plastic, composite, or other material.

As noted below, a transition area is defined by rearward flange93along a front edge of the opening81. It is noted that the wire supports85can be modified to reduce the need for lowering the flange93. Specifically, the modified wire support85′ (FIG. 10D) includes an S-shaped bend at location86″ causing the linear section86′ to be elevated. This allows a thicker foam to be used on the cover82′ to improve seating comfort on the perimeter frame69, while allowing a thin foam (or zero foam) on the wire supports85. Notably, it is desirable to minimize the amount of foam on the wire supports85since “too much” foam would detract from the active independent support provided by the individual wire supports85. This modification also allows for different design alternatives. For example, a cushion sheet82″ of uniform thickness can be rested on the cover82′, with the top surface of the cushion sheet82″ generally aligning with a top surface of the wire linear sections86′. (SeeFIG. 10B.) A sheet of upholstery or fabric (not shown inFIG. 10D) can be laid on the foam cushion and stretched across the seat to cover both the cushion sheet82″ and the wire linear sections86′. In the arrangement ofFIG. 10D, the center area of the rear flange93does not need to be lower than the side areas.

The transition between the front and rear portions75and76is very important, given the flexibility and physical structure of the rear portion76, including its perimeter frame69and the flexible resilient wire supports85. This is especially true considering the angular adjustability of the front portion75on the rear portion76, as discussed below. As illustrated inFIGS. 11-13, the front portion75(FIG. 13) has a “waterfall” shape, with its top surface being curved rearwardly and downwardly toward the opening81in the perimeter frame69, and further it is curved forwardly and downwardly toward a front edge of the seat23. A center rear region92of the front portion75is lower than edge portions, especially as the top surface curves toward the opening81. In particular, the center rear region92can be up to an extra half inch below the top surface of the wire supports85. Further, the rearwardly-extending flange93forming the rear edge facing the opening81is curved downwardly to form a transition that enhances comfort to a seated user who is slouching (i.e. where the person's weight is directed at an angle from a middle of the back22across the opening81and against the flange93). Also, the lowering of the thigh area by one half inch below the wires85improves the transition thigh comfort and perching comfort by allowing for an extra half inch of foam in this area. The lowered area is only in a center region of the front portion75for aesthetic reasons.

A cushion and/or fabric covering95(FIGS. 1-2) is placed on the seat23, and is attached at its front and rear edges to the seat23. A stiff strip (not specifically shown) is attached along front and rear edges of the illustrated fabric95and extends completely across the front and rear edge. The stiff strips are shaped to frictionally tuck into a channel in the front and rear portions75and76. The present description is sufficient for a person skilled in chair design, but additional details are disclosed in the patent application Ser. No. 10/792,309, previously incorporated by reference to the extent they are necessary.

The front portion75(FIG. 8-9) includes a flexible region96connecting it to the rear portion76. It is contemplated that the front portion75could be pivotally or slidably connected to the rear portion76as well. An adjuster97is mounted to change an angle of the front portion75relative to the rear portion76. The illustrated adjuster97includes a pair of links130and131on each side of the chair fit within a pocket at a front of side frame members70and70′ (FIG. 3). The links130and131(FIG. 8) are pivoted to each other at pivot132. The upper link130is pivoted to the front portion75at pivot133and the lower link131is pivoted to the associated side frame member70. When moved over-center in a first direction (FIG. 8), stops135and136on the front portion75and the lower link131engage to limit rotation of the links130and131. This causes the front portion75to stop in a first thigh-angle-supporting position. When moved over-center in a second direction (FIG. 9), stops137and138on the front portion75and the lower link131engage to limit rotation of the links130and131. This causes the front portion75to stop in a second thigh-angle-supporting position. Thus, the adjuster97provides a two-position adjustment for the front portion75of the seat.

A modified adjuster97′ (FIG. 9A) is pivotally mounted by a pivot pin98to a mounting structure on a front of the side frame members70′. The adjuster97′ includes a handle98″ and a spiral slot99′ that engages a guide pin100′ in a side of the front portion75. The spiral slot99′ defines an increasing radius about the axis of the pivot pin98′. The guide pin100′ is located forward of the flexible region96so that, as the adjuster97′ is rotated, the guide pin100′ follows the slot99′ and forces the front portion75angularly downwardly. (SeeFIG. 9Awhich shows a home or “normal” position in solid lines, and which shows a downwardly-adjusted position in dashed lines.) Thus, the adjuster97′ is operably attached to the front end of the side frame members70and to the front portion75for adjusting the front portion75between a first angled position (solid lines) for supporting the thighs of the seated user in a first use position and a second angled position (dashed line) for supporting the thighs in a second lower use position, and is movable to any position therebetween, thus providing infinite adjustability. Notably, the adjuster97′ can include slight continuous friction along its adjustment path, or it can include a plurality of detent bumps along the path to define discrete thigh angle positions.

The handle98of the adjuster97(FIG. 8) (and also handle98″ of adjuster97′) is elongated and has a flat surface that correlates to and generally aligns with the angular position of the front portion75when the front portion75is in either of its up position (FIG. 8) or down position (FIG. 9). Thus, a seated user immediately knows how the front portion75is adjusted, without having to move the handle98between positions. The seated user can tell where the adjuster97is set by feeling the handle98or by looking at the handle98.

A modified seating unit20A (FIGS. 14-15) includes many similar features and aspects of the seating unit20. In seating unit20A, similar and identical components and features are identified by using the same identifying numbers but with the addition of the letter “A”. This is done to reduce redundant discussion. The seating unit20A is close to the seating unit disclosed in the application Ser. No. 10/792,309 previously incorporated herein by reference. The seating unit20A is included herein to show a flexibility of the present inventive concepts, including especially the crossbar (37) and side frame sections (39).

The seating unit20A (FIG. 14) includes a base21A having a housing31A with front and rear pairs of leaf-spring-like resilient support arms32A and32A′ extending laterally and upwardly relative to each side of the housing31A. A link arm64A (FIG. 16) is pivoted to the housing31A at a lower end by a pivot pin119A. The seat23A includes seat-supporting structure36A in the form of crossbar37A and side frame sections39A (FIG. 15). The seat23A is similar to the previously described seat23, and includes a seat perimeter frame69A for supporting a seated user. Addition detail will not be repeated, but it is noted that the application Ser. No. 10/792,309 provides additional discussion and was incorporated by reference above. An upper end of the link arm64A is pivoted to the crossbar37A at a pivot location defined by bracket107A, and a rear end of the side frame sections39A are operably rotatably engaged with the ends of the support arms32A at locations108A. This creates a non-aligned three-point support arrangement for supporting the seat-supporting structure36A on the base21A. The seat23A is slidably positioned on the side frame sections39A for depth adjustment on flanges130A on side frame sections39A that slidably engage mating flanges on the seat frame69A. A latch is positioned between the seat frame69A and side frame sections39A to permit seat depth adjustment.

The back21A (FIGS. 14-15) includes downwardly and forwardly extending arms34A supported on ends of the rear support arms32A′. Further, the back-supporting arms34A are pivoted at location108A to the side frame sections39A. The rear resilient support arms32A′ are held at a forwardly tilted angle and the front resilient support arms32A are held at a rearwardly tilted angle. Due to the interaction of forces, the result is that, upon recline of the back22A, the arms32A and32A′ flex, causing the seat23A moves forwardly and upwardly (the front edge of the seat moving linearly and a rear edge of the seat moving arcuately about the pivot pin119A described below).

A selectively-engaged force-generating device in the form of a torsion spring41A is positioned within the housing31A on the pivot pin119A for rotation about an axis110A. The torsion spring41A (FIG. 17) includes an inner ring member119A′ keyed to the pivot pin119A. Since the pivot pin119A is keyed to the movement of the link arm64A, as the seat23A moves during recline of the back22A, the link arm64A also is forced to move. Thus, the link arm64A rotates in a synchronized coordinated fashion with the back22A when the back22A is reclined. The torsion spring51A further includes an outer ring120A with a radially-extending interference leg116A, and a rubber torsion spring element121A between the inner and outer ring members118A and120A. A selector stop member111A is positioned on a pair of guide rods112A and113A within the housing31A for lateral sliding movement via a Bowden cable and a remote control handle on a side of the seat23A. When the selector stop member111A is in a first position (FIG. 18), the selector stop member111A does not engage the interference leg116A on the torsion spring41A but instead misses the leg116A. As a result, the leg116A (and spring41A) is free to rotate, and does not provide any back support upon recline. Instead, the back support upon recline comes from the upward and forward movement of the seat23A during recline (which is a weight-activated support feature where heavier seated users receive greater back support due to their heavier body weight), in combination with the energy-absorption that occurs by flexing of the resilient arms32A and32A′. Since the torsion spring41A freely rotates, the torsion spring41A is not active, and does not provide any bias during recline of the back22A. Contrastingly, when the selector stop member111A is moved to a second position (FIG. 19), the selector stop member111A engages the outer leg116A, preventing the outer ring120A from rotating. At the same time, the keyed inner ring member118A moves with the pivot pin119A since it is keyed to the pivot pin119A. This causes the torsion spring element121A to be stretched and to provide a biasing force, called a “booster” force herein since it “boosts” (i.e. in other words increases) the amount of energy provided upon recline of the back22A.

The modified control mechanism24D (FIG. 20) includes a housing121D with top, side, front and rear walls600-603defining a downwardly open cavity604closed by cover115D. Up flanges604on the cover115D combine with features inside the housing121D to retain the axle-forming pivot pin133D (recall that pin133D is supported in the housing121D and rotatably supports the seat-attached link132D and rotatably supports the torsional booster spring150D), and the features are also used to retain the parallel rods606and607for slidably supporting the stop member155D. The top wall600includes a raised area608for abutting a triangular mount609attached to the cross beam323D of the seat frame330D, and further includes a slot610for receiving an upper arm132D′ on the link132D.

The stop member155D (FIGS. 20-22A) is slidably carried by rods606and607for laterally sliding movement. The stop member155D includes first and second stop surfaces612and613(FIG. 22A), which are angularly stepped from each other to define different angular positions relative to the axle-forming pivot pin133D. The link132D (FIG. 22) includes a mating stop surface614on its arm203D, and the torsional booster spring150D includes a mating stop surface615on its outer sleeve's arm154D. In a first (home) position (FIG. 23), the stop member (155D) is laterally shifted toward one side so that it is positioned out of the way, such that the stop surfaces612and613do not engage any mating surface. Hence, the back23D is supported only by the energy stored in the compliant springs123D′ and137D (and the potential energy stored as the seated user is lifted by the seat22D during recline of the back23D).

In a second position (FIG. 24), the stop surface612engages the stop surface615on the spring arm154D, such that the booster spring150D is engaged and supplements (i.e., adds to) the back supporting force during recline of the back23D. Notably, the back23D is permitted to move to a full recline position. In a third position (FIG. 25), the stop surface613engages the mating stop surface614on the link132D. Since the stop surface613is angularly stepped from the stop surface612, the back23D is permitted a partial recline before the stop surface613engages the link's stop surface614. Notably, the stop surface612of the stop member155D engages the stop surface615, such that the booster spring150D is continuously engaged during this partial recline. In a fourth position (FIG. 26), the stop surface612engages the stop surface614of the link132D, preventing any recline of the back23D (i.e. “zero recline”).

Advantageously, the only frictional force that must be overcome when moving the stop member155D is the effort to slide the stop member155D along rods606and607, which is designed to have a very low frictional force. Thus, normally, a very low “shifting force” is required. It is contemplated that the shifting force for moving the stop member155D can be provided by a Bowden cable with telescoping internal wire that is stiff enough to provide both a “push” shifting force and a “pull” shifting force.

A seating unit220(FIG. 27) includes a back support221and seat222supported for synchronous movement by a base223. The back support221includes a perimeter frame224defining an opening225, and includes a plurality of resilient members226(i.e., spring steel wires) spanning the opening for flexibly supporting a seated user. An upholstery cover227extends over and covers the resilient members226and covers a front of the perimeter frame224. A bow-tie-shaped lumbar device228is positioned between the cover227and sides of the perimeter frame224for vertical adjustment. The lumbar device228includes a bow-tie-shaped flexible body229with end sections230defining a greater vertical dimension D1than a middle section231of the body229. Upper and lower edges232and233of the end sections230are thin and serve to wedgingly slip between the cover227and the resilient members226in a manner leading the middle over irregular surfaces between the resilient members226. A thick middle area between the upper and lower edges232and233causes a change in lumbar support force and shape as the lumbar device228is vertically adjusted. Handles235are attached to the body229by stretchable fabric loops236, permitting the handles235to track along non-parallel side frame portions of the perimeter frame224during lumbar adjustment.

The perimeter frame224(FIG. 34) includes a lower perimeter member238and an upper perimeter member239attached to the lower perimeter member238by screws240. The lower perimeter member238includes side frame sections241defining a plurality of pockets242that are elongated in a direction toward the opening225defined by the perimeter frame224. The pockets242have an access opening243that opens across a radiused surface244on the lower perimeter member238. The upper perimeter member239covers the access opening243. The resilient members226are steel wires having an L-shaped end226′ positioned in the pockets242for sliding movement. The pockets242limit inward sliding motion of the resilient members226. The ends of the resilient members226are operably mounted to slide as the resilient members226flex, thus providing distributed support for point loads (which is particularly comfortable to a seated user), while eliminating high inward stress on the side frame sections241as a middle of the resilient members226are rearwardly loaded. The present description is sufficient for a person of ordinary skill to understand the present invention, but it is noted that the details of the function and operation of the perimeter frame224and resilient members226are described in more detail in the application Ser. No. 10/792,309 incorporated herein by reference above.

The illustrated resilient members226are spring steel wires having round cross sections. However, it is contemplated that a scope of the present invention also includes other resilient support members, such as flat springs, non-metal plastic springs, springs made from composite materials, and other resilient support means.

It is contemplated that the present cover227(FIG. 34) can be a variety of different materials for covering the perimeter frame224and resilient members226. Notably, the resilient members226are sufficiently comfortable, such that it is not necessary that the cover227include a cushion or compressible material. However, the illustrated cover227includes a three-dimensional fabric known as a “technical material.” The illustrated cover227includes first and second layers of woven material separated by resilient strands that connect the first and second layers to provide a cushioning member that provides air flow and that is recyclable. It is also contemplated that the cover227can be a subassembly of a foam cushion and fabric upholstery. A stiffener246(FIG. 28) is attached to a back surface of the cover227, and includes side strips247that support and stabilize the edges of the cover227. The stiffener246also includes top and bottom strips (not specifically shown) that form a perimeter around the entire cover227for stabilizing the cover227. The top and bottom edges of the cover227are attached to the perimeter frame224. This can be accomplished in a number of different ways. In the illustrated arrangement, a hooked ridge248(FIG. 28A) is attached to an edge of the cover227, and is tucked into a mating channel249along an upper edge250of the perimeter frame224with a “zip lock” like action. A similar connection is provided at a bottom of the cover227. The present description is sufficient for a person of ordinary skill to understand the present invention, but it is noted that the details of the function and operation of the cover attachment is described in more detail in the application Ser. No. 10/792,309 incorporated herein by reference above.

The lumber device228(FIG. 29) includes the body229, and a wire251that connects fabric elastic loops236and handles235to the body229. Specifically, the body229has a bow-tie shape formed by a unitary thermoformed (or injection-molded) sheet with vertically-enlarged end sections230defining a dimension D1and a vertically narrower middle (when viewed in plan view). The body229has narrow upper and lower edges232and233and a thick middle section when viewed in side view from its end. The upper and lower edges232and233of the end sections230are limited to the thickness of the sheet material such that they are thin and serve to wedgingly slip between the cover227and the resilient members226in a manner leading the middle over irregular surfaces between the resilient members226. Further, the edges232and233are near to the perimeter frame224where they are best able to slip between the cover227and the perimeter frame224, even if a seated user is leaning against the back.

The body229(FIG. 29) is molded to have first wall portions252formed to define a first surface and second wall portions253formed to define a second surface. Third wall portions254extend between the first and second wall portions252and253to define space therebetween. The wall portions253and254form cube-shaped hollow blocks that look much like an ice cube tray (though they are triangularly-shaped when viewed from an end). The hollow blocks have sufficient strength to maintain their shape when compressed, with the wall portions252being a base layer that is relatively flat. The areas between the blocks define vertical and horizontal grooves256and257that are relatively flexible since they lack a three-dimensional shape. Thus, while the body229is able to create space between the cover227and the resilient members224, the body229is also flexible and able to conform to any shape defined by the plurality of resilient members224. By this arrangement, the body229provides a desired shape change as the lumbar device is vertically adjusted, yet the lumbar device228supplements and complements the lumbar support force already provided by the resilient members224in a lumbar region of the back support221without destroying the beneficial comfortable support provided by the resilient members224.

The outboard ends of the body229(FIG. 29) include a bridge flange258having a passageway259under the flange258. The flange258is supported by reinforcing ribs260at each end. Fabric loops236extend through the passageway259under the flange258. The horizontal groove257includes sufficient space for receiving a linear mid-section of the wire251, and further includes at least two pair of opposing bumps261forming a resilient detent for frictionally snappingly engaging the wire251to hold it in position in the horizontal groove257. There is a space262between the flange258and the end of the hollow blocks formed by wall portions253-254, and the wire251includes back-and-forth “L” bends263shaped to fit into the space flat against the body229.

The handles235(FIG. 29) each include an L-shaped grip264having a flat portion265, and a perpendicular outer flange266for slidably engaging a front and outer surface of the side frame members241. A protrusion267extends from the flat portion265inboard of the outer flange266. The protrusion267slidably engages a slot268(FIG. 28) in a front of the side frame member241for guiding and also limiting the vertical adjustment of the handles235. A loop270(FIG. 29) is formed on an inboard end of the grip264, and includes a hole271through which the fabric loop236is positioned. The handles235are attached to the ends of the body229by the stretchable fabric loops236, permitting the handles235to track along non-parallel side frame portions of the perimeter frame224during lumbar adjustment.

Assembly of the lumbar device228(FIG. 29) is very straightforward. A strip of fabric is extended through a hole271on each handle235and sewn to form the fabric loops236. The fabric loops236are extended through the passageways259under flanges258on each end of the body229, and the “L” bends263of the wire251are passed through the fabric loops236. The wire251is then snapped into the groove257, where it is retained in place by the detent bump261. The lumbar device228is then positioned between the cover227and the back frame224, with the handles235being located on each side and with the protrusions267operably engaging the slots268in the side frame sections241. The elastic fabric loops236are stretchable and are stretched when assembled, such that they tension the handles235against the side frame sections241to provide friction to hold the lumbar device228in a selected adjusted position.

The lumbar device427D (FIGS. 35-37) is positioned between the back covering656and the back frame270D. The lumbar device427D can be shifted vertically between the protrusions672and673for adjusting the lumbar support provided. The lumbar device427D (FIG. 36) includes a wire680, front and rear bow-tie-shaped thin panels681and682, and opposing handles683. The wire680is generally rectangular, and includes long resilient straight sections684and short ends685. The thin panels681and682capture the wire680therebetween. It is contemplated that the thin panels681and682can be held together in different ways. For example, the two parts can be held together by separate fasteners (e.g., rivets, screws, mechanical interlocks, snaps), or can be held together by bonding techniques (e.g., heat staking, ultrasonic bonding, adhesive), or by other means known in the art. It is contemplated that the lumbar panels681and682can be extruded or molded. It is also contemplated that they can be made as a single part, with the panels681and682being held together with an integrally-molded living hinge and with a hook and tab feature opposite the living hinge for securement.

Unlike prior art lumbar devices, it is contemplated that the front and rear thin panels681and682are as thin as possible and are surprisingly flexible, so that the lumbar support comes from the active flexing of the wire680, rather than from a stiff flat part. Thus, the lumbar support provided is very much like the support provided by the wires278D in “comfort surface” of the back223D. As a result, the lumbar support comes from the increase in force versus displacement curve provided (i.e., the wire680of the lumbar device supplements the wires278D of the back223D) . . . instead of the increased lumbar support coming only from a forced shape change in the lumbar area of the back223D. Nonetheless, it is contemplated that increased lumbar support can come from both a lumbar shape change and also an increased lumbar support force curve.

The wire680is able to flex and move within and between the panels681and682, and the ends685of the wire680extend outward from ends of the panels681and682. Handles683include a thin body688with a U-shaped cavity689for receiving the ends685. A handle690is attached to an end of components680,681,682, and extends outward from them to form a grip to facilitate adjustment of the lumbar device427D that can be grasped from a side of the chair220D. The wire680can be snapped into position or a second tab or a clip691can be provided to loosely retain the wire680slidably within the U-shaped cavity689. Advantageously, one or both sides of the lumbar device427D can be adjusted, so that an optimal comfortable support can be obtained. The lumbar device427D is held in place by the tension of the back covering656, which, due to the curvature of the back, causes tension between the back covering656and the back frame667.

It is contemplated that the wire loop680can be replaced with a flat strip of spring metal or leaf-spring-like plastic member. In fact, the entire lumbar wire680and “clam shell” covers681,682could be replaced with a single molding or stamping, with its handles242being formed on or attached to ends of the lumbar device.

Another lumbar device427E (FIGS. 39-41) includes a rectangular wire684E positioned inside of a sock682E of slightly-elastic material, such as slippery LYCRA® material. The sock material can be black, fabric-color, patterned, see-through, or translucent. Handles683E are attached to ends682E′ of the sock682E. The handles683E include an outer end section800E with a lip801E forming a recess802E that slidably engages a front surface of the back frame side sections271E. The inboard end804E is offset from an intermediate section805E to form a shelf for supporting the end of the wire684E that is co-planar with the outer end section800E. An end682E′ of the sock682E is fed through an aperture806E in the intermediate section805E. The end682E′ is doubled back and either looped around an anchor807E or is secured (e.g., by stapling or fastener808E) to the handle683E.

The lumbar device427E is positioned under the upholstery back covering and in front of the back frame side sections271E, with the handles683E slidably engaging the side section271E. If the back frame side sections271E are non-parallel, the sock682E stretches (or elastically shrinks) to compensate as the lumbar device427E is moved vertically. The slipperiness of the sock682E helps the lumbar device427E slip up and over each successive back wire278E as the lumbar device427E is vertically adjusted. The long parallel sections of the wire684E can be (but do not necessarily need to be) bent to form a slightly bowtie-shaped arrangement, which shape also helps slip up and over each successive wire278E.