CHAIR CONTROL MOUNT

Abstract

A control assembly for a chair includes a base structure having a first pivot point and a second pivot point separate from the first pivot point, a seat support structure having a front portion rotatably coupled to an upper portion of the base structure to rotate about the first pivot point, a seat support structure having a front portion rotatably coupled to an upper portion of the base structure to rotate about the first pivot point, and a backrest support structure having a front portion rotatably coupled to a lower portion of the base structure to rotate about the second pivot point.where the backrest support structure is adapted to move between a first and a second position and a control link having a first end rotatably coupled to a lower portion of the seat support structure to rotate about a third pivot point, and a second end rotatably coupled to a front portion of the backrest support structure to rotate about a fourth pivot point.

Description

CHAIR CONTROL MOUNT BACKGROUND OF THE INVENTION The present invention relates to a control assembly of a chair assembly, and in particular to a control assembly comprising a 4-rod link assembly, adapted to control a movement of a seat support structure relative to the movement of the backrest support structure. BRIEF DESCRIPTION OF THE INVENTION One aspect of the present invention is to provide a control assembly for a chair comprising a base structure defining an upper portion having a first pivot point and a lower portion located below the upper portion and having a second pivot point separate from the first pivot point, wherein the base structure is adapted to join a base support structure that is spliced ​​to the floor, and a seat support structure having a front portion rotatably coupled to the upper portion of the base structure to rotate about the first pivot point and a rear portion located behind the front portion, and wherein the seat support structure is adapted to support a seated user.The control assembly further comprises a backrest support structure having a front portion rotatably coupled to the lower portion of the base structure to rotate about a second pivot point and a rear portion located behind the front portion, where the seat support structure is adapted to move between a first position and a second position, and a control link having a first end rotatably coupled to the rear portion of the seat support structure to rotate about a third pivot point, and a second end rotatably coupled to the rear portion of the backrest support structure to rotate about a fourth pivot point. Another aspect of the present invention is providing a control assembly for a chair comprising a base structure having a first pivot point and a second pivot point separate from the first pivot point, wherein the base structure is adapted to be joined to a base support structure that is spliced ​​to the floor, and a seat support structure rotatably coupled directly to the base structure to rotate about the first pivot point, and wherein the seat support structure is adapted to support a seated user.A control assembly further comprises a backrest support structure rotatably coupled directly to the base structure to rotate about the second pivot point where the backrest support structure is adapted to rotate between a first position and a second position, and a control link having a first end operatively coupled to the seat support structure, and a second end operatively coupled to the backrest support structure where the control link rotates the support structure at a slower rotational speed than the rotational speed of the backrest support structure when the backrest support structure is rotated between the first and second positions. Another aspect of the present invention is to provide a control assembly for a chair comprising a base structure defining a first pivot point and a second pivot point separate from the first pivot point, wherein the base structure is adapted to be attached to a support structure RAQQnn / LZnZ / E / Yli of a base that is spliced ​​to the floor, and a seat support structure rotatably coupled to the first pivot point, where the seat support structure is adapted to support a seated user.The control assembly further comprises a backrest support structure rotatably coupled to the second pivot point, wherein the backrest support structure is adapted to move between a first position and a second position, and wherein the base structure does not move when the backrest support structure moves between the first and second positions, and a control link rotatably coupled to the rear portion of the seat support structure to rotate about a third pivot point, and rotatably coupled to the backrest support structure to rotate about a fourth pivot point, wherein the distance between the first pivot point and the second pivot point is greater than the distance between the third pivot point and the fourth pivot point. Another aspect of the present invention is to provide a control assembly for a chair comprising a base structure including a first pivot point and a second pivot point separate from the first pivot point, wherein the base structure is adapted to join to a base structure spliced ​​to the floor, a seat support structure rotatably coupled directly to the base structure to rotate about the first pivot point, and wherein the seat support structure is adapted to support a seated user, and a backrest support structure rotatably coupled directly to the base structure to rotate about the second pivot point,where the backrest support structure is adapted to move between the first full-travel position and the second full-travel position opposite the first full-travel position. The control assembly also comprises a control link having a first end operatively coupled to the seat support structure, and a second end rotatably coupled to the seat support structure, where the control link is adapted to move between a first position and a second position when the backrest support structure moves between the first full-travel position and the second full-travel position.The control link includes a longitudinally extending shaft adapted to form a first angle with a seat support surface of the seat support structure when the control link is in the first position and a second angle with the seat support surface of the seat support structure when the control link is in the second position; the first angle is an acute angle, and the shaft of the control link does not rotate substantially beyond perpendicular to the seat support surface when the control link moves between the first and second positions. Another aspect of the present invention is to provide a control assembly for a chair comprising a base structure defining an upper portion and a lower portion located below the upper portion, a seat support structure having a front portion operatively coupled to the base structure and a rear portion located behind the front portion, wherein the seat support structure is adapted to support a seated user, and a backrest support structure having a front portion operatively coupled to the base structure and a rear portion located behind the front portion, wherein the backrest support structure RRQQnn / LZnZ / E / Yli is adapted to move between a first position and a second position. The control assembly further comprises a link having a first end operatively coupled to the rear portion of the seat support structure, and a second end operatively coupled to the rear portion of the backrest support structure, wherein a selection of one of the base structure and the control link is fixed to rotate with respect to a floor support surface when the backrest support moves between the first and second positions. Another aspect of the present invention is to provide a control assembly for a chair comprising a base structure including a first pivot point and a second pivot point separate from the first pivot point, wherein the base structure is adapted to join the base support structure that is spliced ​​to the floor, a seat support structure rotatably coupled directly to the base structure to rotate about the first pivot point, wherein the seat support structure is adapted to support a user seated thereon, and a backrest support structure rotatably coupled directly to the base structure to rotate about the second pivot point, wherein the backrest support structure is adapted to move between a first position and a second position.The control assembly also includes a control link having a first end operatively coupled to the seat support structure, and a second end operatively coupled to the seat support structure, and at least one deflection assembly exerting a deflection force torsion around the second pivot point that exerts a deflection force against the backrest support structure that deflects the backrest support structure from the second position to the first position, wherein the portion of the deflection force around is adjustable between the first and second magnitudes when the backrest support structure is in the first position, and wherein the second magnitude is greater than the first magnitude. Another aspect of the present invention is to provide a control assembly for a chair comprising a base structure adapted to join to a base support structure that is spliced ​​to the floor, a seat support structure adapted to couple to the base structure, wherein the seat support structure is adapted to support a user seated thereon, and a backrest support structure operatively coupled to the base structure, wherein the backrest support structure is adapted to move between a first position and a second position.The control assembly also further comprises at least one deflection assembly that exerts a deflection force that deflects the backup support structure from the second position to the first position, wherein the deflection force is adjustable between a first and a second magnitude when the backup support structure is in the first position, and wherein the second magnitude is greater than the first magnitude, and an auxiliary adjustment assembly that exerts an auxiliary force on the deflection assembly, thereby reducing the required input force that must be applied by the user to adjust the deflection force between the first and second magnitudes. These and other features and advantages of the present invention will be better understood and appreciated by those skilled in the art with reference to the following specification, claims and accompanying Figures. RRQQnn / LZnZ / E / Yli BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a front perspective view of a chair assembly incorporating the present invention; Figure 2 is a rear perspective view of the chair assembly; Figure 3 is a side elevation view of the chair assembly showing the chair assembly in a lowered position and in a raised position in dashed lines, and a seat assembly in a retracted position and in an extended position in dashed lines; Figure 4 is a side elevation view of the chair assembly showing the chair assembly in an upright position and in a reclined position in dashed lines; Figure 5A is an exploded view of the chair assembly; Figure 5B is an enlarged perspective view of the chair assembly with a portion of the seat assembly removed to illustrate a spring or coil support assembly; Figure 6 is a perspective view of the seat assembly exploded view; Figure 7 is a top perspective view of the seat assembly; Figure 8 is a bottom perspective view of the seat assembly; Figure 9 is a bottom perspective view of the exploded view, the cover assembly, and the seat assembly; Figure 10 is a cross-sectional view of the cladding assembly; Figure 11 is a perspective view of the exploded view of an alternative seat assembly; Figure 11A is a perspective view of the exploded view of another alternative seat assembly; Figure 12 is a top perspective view of the alternative seat mounting configuration; Figure 13 is a bottom perspective view of the alternative seat mounting configuration; Figure 14 is a bottom perspective view of the exploded view of the alternative seat assembly modality; Figure 15 is a top perspective view of a second alternative mode of seat mounting; Figure 16 is a cross-sectional view of the second alternative seat mounting modality taken along line XVI-XVI, Figure 15; Figure 17 is a cross-sectional view of the second alternative seat mounting modality taken along line XVII-XVII, Figure 15; Figure 18 is a front perspective view of a backup assembly; Figure 19 is a side elevation view of the backup assembly; Figure 20A is a front perspective view of the exploded view of the backrest assembly; Figure 20B is a rear perspective view of the exploded view of the backup assembly; Figure 21 is an enlarged perspective view of an area XXI, Figure 20A; Figure 22 is an enlarged perspective view of an area XXII, Figure 2; Figure 23 is a cross-sectional view of a backup pivot assembly taken along RAQQnn / LZnZ / E / Yli line XXIII-XXIII, Figure 18; Figure 24A is a rear perspective view of the exploded view of the upper back pivot assembly; Figure 24B is a front perspective view of the exploded view of the upper backrest pivot assembly; Figure 25 is an enlarged perspective view of area XXV, Figure 20B; Figure 26A is an enlarged perspective view of a comfort member and lumbar mount; Figure 26B is a rear perspective view of the comfort member and lumbar assembly; Figure 27A is a front perspective view of a ratchet member; Figure 27B is a rear perspective view of the ratchet member; Figure 28 is a partial cross-section perspective view along line XXVIII-XXVI11, Figure 26B; Figure 29A is a perspective view of the backrest assembly, where a portion of the comfort member is cut out; Figure 29B is an enlarged perspective view of a portion of the backup assembly; Figure 30 is a perspective view of an alternative lumbar mounting modality; Figure 31 is a cross-sectional view of the backrest assembly and upholstery assembly; Figures 32A-32D are views of the staggered assembly of the backrest assembly and the upholstery assembly; Figure 33 is an enlarged perspective view of area XXXIII, Figure 32A; Figures 34A-34H are a series of rear elevation views of a joining bracket and the sequential steps of a traction strap secured to it; Figures 35G-35H are alternative sequential steps for securing the pull strap to the joining bracket; Figure 36 is an exploded view of an alternative mode of the backup assembly; Figure 37 is a cross-sectional side view of an upper portion of the alternative mode of the backup mounting; Figure 38 is a cross-sectional side view of a side portion of the alternative mode of the backup mounting; Figure 39 is a front elevation view of a reinforcing member; Figure 40 is a front elevation view of the reinforcing member in an inside-out orientation; Figure 41 is a partial front elevation view of the reinforcing member stitched to the lining member; Figure 42 is a perspective view of a control input assembly supporting a seat support plate above it; Figure 43 is a perspective view of the control input assembly with certain elements removed to show the interior of the assembly; RRQQnn / LZnZ / E / Yli Figure 44 is an exploded view of the control input assembly; Figure 45 is a side elevation view of the control input assembly; Figure 46A is a front perspective view of a back support structure; Figure 46B is a perspective view of the exploded view of the back support structure; Figure 47 is a side elevation view of the chair assembly illustrating its multiple pivot points; Figure 48 is a side perspective view of the control assembly showing multiple pivot points associated with it; Figure 49 is a cross-sectional view of the chair showing the backrest in an upright position with the lumbar adjustment set in a neutral setting; Figure 50 is a cross-sectional view of the chair showing the backrest in an upright position with the lumbar portion adjusted to a flat configuration; Figure 51 is a cross-sectional view of the chair showing the reclined backrest with the lumbar portion adjusted to a neutral position; Figure 52 is a cross-sectional view of the chair in a reclined position with the lumbar portion adjusted to a flat configuration; Figure 52A is a cross-sectional view of the chair showing the reclined backrest with the lumbar portion of the frame fixed at maximum curvature; Figure 53 is an exploded view of a moment arm deflection assembly; Figure 54 is a cross-section perspective view of the moment arm deflection assembly taken along line LIV-LIV, Figure 43; Figure 55 is a top plan view of a plurality of control links; Figure 56 is an exploded view of a control link assembly; Figure 57A is a side perspective view of the control assembly with the moment arm deflection in a low-tension position and the chair assembly in a vertical position; Figure 57B is a side perspective view of the control assembly with the moment arm deflection in a low-tension position and the chair assembly in a reclined position; Figure 58A is a side perspective view of the control assembly with the moment arm deflection in a high-tension position and the chair assembly in a vertical position; Figure 58B is a side perspective view of the control assembly with the moment arm deflection in a high-tension position and the chair assembly in a reclined position; Figure 59 is a portion versus recline quantity diagram for low and high tension settings; Figure 60 is a perspective view of a direct drive assembly with the exploded view of its seat support plate; Figure 61 is a perspective view of the exploded view of the direct drive assembly; Figure 62 is a perspective view of a vertical height control assembly; Figure 63 is a perspective view of a vertical height control assembly; Figure 64 is a side elevation view of the vertical height control assembly; RRQQnn / LZnZ / E / Yli Figure 65 is a cross-section perspective view of a first inlet control assembly along the LXV-LXV line, Figure 42; Figure 66A is a perspective view of the exploded view of a control input assembly; Figure 66B is an enlarged perspective view of a clutch member of a first control input assembly; Figure 66C is a perspective view of the exploded view of the control input assembly; Figure 67 is a side elevation, cross-section view of a variable backup control assembly taken along line LXVI l-LXVIl, Figure 42; Figure 68 is a perspective view of an arm assembly; Figure 69 is a perspective view of the arm assembly exploded view; Figure 70 is a side elevation view of the arm assembly in a raised position and a lowered position shown in dashed lines; Figure 71 is a partial cross-sectional view of the arm assembly; Figure 72 is a top plan view of the chair assembly showing the arm assembly in an in-line position and angled positions in dashed lines; Figure 73 is a perspective view of an arm assembly that includes a vertical height adjustment lock; Figure 74 is a side elevation view of an arm assembly that includes a vertical height adjustment lock; Figure 75 is a perspective view of an arm assembly that includes a vertical height adjustment lock; Figure 76 is a top plan view of the chair assembly showing an armrest assembly in an in-line position and rotated positions in dashed lines, and in a retracted position and an extended position in dashed lines; Figure 77 is a perspective view of the exploded view of the armrest assembly; Figure 78 is a cross-sectional view of the armrest assembly taken around line LXXVII l-LXXVI II, Figure 70; Figure 79 is a perspective view of a chair assembly; Figure 80 is a front elevation view of the chair assembly as shown in Figure 79; Figure 81 is a first side elevation view of the chair assembly as shown in Figure 79; Figure 82 is a second side elevation view of the chair assembly as shown in Figure 79; Figure 83 is a rear side elevation view of the chair assembly as shown in Figure 79; Figure 84 is a top plan view of the chair assembly as shown in Figure 79; Figure 85 is a bottom plan view of the chair assembly as shown in Figure 79; Figure 86 is a perspective view of a chair assembly without an armrest assembly; Figure 87 is a front elevation view of the chair assembly as shown in Figure 86; RRQQnn / LZnZ / E / Yli Figure 88 is a first side elevation view of the chair assembly as shown in Figure 86; Figure 89 is a second side elevation view of the chair assembly as shown in Figure 86; Figure 90 is a side elevation view of the chair assembly as shown in Figure 86; Figure 91 is a top plan view of the chair assembly as shown in Figure 86; and Figure 92 is a bottom plan view of the chair assembly as shown in Figure 86. DETAILED DESCRIPTION OF THE INVENTION For descriptive purposes herein, the terms “top,” “bottom,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in Figure 1. However, it should be understood that the invention may assume various orientations and alternative sequences of steps, except where expressly specified otherwise. It should also be understood that the devices and processes illustrated in the accompanying Figures and described in the following specification are exemplary embodiments of the inventive concepts defined in the appended claims. Accordingly, the specific dimensions and other features relating to the embodiments described herein shall not be considered limiting unless expressly stated otherwise in the claims.The various elements of the modalities described here can be described as being operationally coupled to one another, which includes elements coupled directly or indirectly. Furthermore, the term “chair” used here encompasses various seating arrangements such as office chairs, vehicle seats, home chairs, stadium seats, theater seats, and the like. The numerical reference 10 (Figures 1 and 2) generally designates a chair assembly incorporating the present invention. In the illustrated example, the chair assembly 10 includes an oriented base assembly 12 that is spliced ​​to a supporting floor surface 13, a control or support assembly 14 supported by the oriented base assembly 12, a seat assembly 16 and a backrest assembly 18, each operatively coupled to the control assembly 14, and a pair of arm assemblies 20. The control assembly 14 (Figure 3) is operatively coupled to the base assembly 12, such that the seat assembly 16, the backrest assembly 18, and the two arm assemblies 20 can be adjusted vertically between a fully lowered position A and a fully raised position B, and rotated about a vertical axis 21 in a direction 22.The seat assembly 16 is operatively coupled to a control assembly 14 such that the seat assembly 16 is longitudinally adjustable with respect to the control assembly 14 between a fully retracted position C and a fully extended position D. The seat assembly 16 (Figure 4) and a backrest assembly 18 are operatively coupled to a control assembly 14 and to each other, such that the backrest assembly 18 moves between a fully upright position E and a fully reclined position F, and furthermore such that the seat assembly 16 moves between a fully upright position G, and a fully reclined position H corresponding to the fully upright position E and the fully reclined position F of the backrest assembly 18, respectively. RRQQnn / LZnZ / E / Yli The base assembly 12 includes a plurality of pedestal arms 24 extending radially and spaced around a hollow central column 26 that receives a pneumatic cylinder 28 thereon. Each pedestal arm 24 is supported above the floor surface 13 by an associated wheel assembly 30. Although the base assembly 12 is illustrated as including a multi-arm pedestal assembly, it should be noted that other suitable support structures may be used, including, but not limited to, fixed columns, multi-cap arrangements, vehicle seat support assemblies, stadium seating arrangements, house chair arrangements, theater seating arrangements, and the like. The seat assembly 16 (Figure 5A) includes a relatively rigid seat support plate 32 having a front edge 34, a rear edge 36, and a pair of C-shaped guide rails 38 defining the side edges of the seat support plate 32 (Figure 5B) extending between the front edge 34 and the rear edge 36. The seat assembly 16 further includes a flexible, elastic outer seat frame 40 having a pair of upwardly turned side portions 42, and an upwardly turned rear portion 44 cooperating to form a generally upwardly concave shape, and a front edge 45. In the illustrated example, the seat frame 40 is comprised of a relatively flexible material such as thermoplastic elastomer (TPE).In the assembly, the end seat frame 40 is secured and sandwiched between the seat support plate 32 and a flexible plastic seat tray 46, to which the seat support plate 32 and a plurality of mechanical fasteners are secured. The seat tray 46 includes a leading edge 48, a trailing edge 50, side edges 52 extending between the leading edge 48 and the trailing edge 50, and a top surface 54 and a lower surface 56 that cooperate to form a generally upward-facing concave shape. In the illustrated example, the seat tray 46 includes a plurality of longitudinally extending grooves 58, extending forward from the trailing edge 50. The grooves 58 cooperate to define a plurality of fingers 60 between them, each finger 60 being individually elastic and flexible.The seat tray 46 further includes a plurality of elongated, laterally oriented openings 62 located near the front end 48. The openings 62 cooperate to increase the overall flexibility of the seat tray 46 in the area thereof, and specifically allow a front portion 64 of the seat tray 46 to flex in a vertical direction 66 with respect to a rear portion 68 of the seat tray 46, as discussed later. Seat assembly 16 further includes a foam cushion member 70 having a top face 76, and resting on the top surface 54 of the seat tub 46 and cradled within the outer seat frame 40. Seat assembly 16 further includes a fabric seat cover 72 having a front edge 73, a rear edge 75, and a pair of side edges 77 extending between the front edge 73 and the rear edge 75.A spring support assembly 78 (Figures 5A and 5B) is secured to the seat assembly 16 and is adapted to flexibly support the front portion 64 of the seat tray 46 to flex in the vertical direction 66. In the illustrated example, the spring support assembly 78 includes a support housing 80 comprising a foam and having side portions 82 that define an upwardly concave, arched shape. The spring support assembly 78 further includes a relatively rigid connecting member 84 that extends laterally between the side portions 82 of the support housing 80 and is located between the support housing 80 and the front portion 64 of the seat tray 46. A plurality of metal fasteners 86 secure the housing. The support and connecting member 84 are attached to the front portion 64 of the seat basin 46. The spring support assembly 78 further includes a pair of cantilever springs 88, each having a distal end 90 received through a corresponding opening 92 in the connecting member 84, and a proximal end 94 secured to the seat support plate 32, so that the distal end 90 of each cantilever spring 80 can flex in the vertical direction 66. A pair of linear bearings 96 are fixed to the connecting member 84 and aligned with openings 92 therein, so that each linear bearing 96 slides to receive the distal ends 90 of a corresponding cantilever spring 88.In operation, the cantilever springs 88 cooperate to allow the front portion 64 of the seat tray 46, and more generally the entire front portion of the seat assembly 16, to flex in the vertical direction 66 when a seated user turns forward on the seat assembly 16 and exerts a downward force on the front edge thereof. Reference number 16a (Figure 6) generally designates another embodiment of the seat assembly of the present invention. Since seat assembly 16a is similar to seat assembly 16 previously described, the similar parts shown in Figures 5A and 6-10, respectively, are represented by the same corresponding reference number, except for the suffix “a” in the numbers of the latter in the illustrated example. Seat assembly 16a includes a relatively rigid seat support plate 32a having a front edge 34a, a rear edge 36a, and a pair of C-shaped guide rails 38a that define the lateral edges of the seat support plate 32a and extend between the front edge 34a and the rear edge 36a.The seat assembly 16a further includes a flexible, elastic external seat frame 40a (Figures 6 and 7) having a pair of upward-turned side portions 42a, each terminating in a side rim 43a, a front rim 45a, and an upward-turned rear portion 44a terminating in a rear rim 47a and including a flap portion 49a, wherein the side portions 42a and the rear portion 44a cooperate to form an overall upward-facing, three-dimensional, concave shape. The seat frame 40a is comprised of a relatively flexible material such as a thermoplastic elastomer (TPE) and molded as a single integral piece.In the assembly, described in more detail below, the external seat frame 40a is secured and sandwiched between the seat support plate 32a and a flexible, elastic plastic seat tray 46a, which is secured to the seat support plate 32a by means of a plurality of mechanical fasteners. The seat tray 46a includes a front rim 48a, a rear rim 50a, side rims 52a extending between the front rim 48a and the rear rim 50a, a top surface 54a, and a bottom surface 56a that cooperate to form a generally upward-facing, concave shape. In the illustrated example, the seat tray 46a includes a plurality of longitudinally extending grooves 58a that extend forward from the rear rim 50a. The grooves 58a cooperate to define a plurality of fingers 60a between them, each finger 60a being individually elastic and flexible.The seat tray 46a further includes a plurality of elongated, laterally oriented slots 62a located near the leading edge 48a. The openings 62a cooperate to increase the overall flexibility of the seat tray 46a in the area thereof, and specifically allow a leading portion 64a of the seat tray 46a to flex in a vertical direction 66a with respect to a trailing portion 68a of the seat tray 46a as discussed later. The seat assembly 16a further includes a RRQonn / Lznz / E / Yu foam cushion member 70a having a top surface 76a, and resting on the top surface 54a of the seat tub 46a and cradled within the outer frame 40a. The seat assembly 16a further includes a fabric seat cover 72a having a front rim 73a, a rear rim 75a, and a pair of side rims 77a extending between them. The seat assembly 16a is supported by a spring support assembly 78a (Figure 6) that is similar in construction and operation to the previously described spring support assembly 78. As best illustrated in Figures 7 and 8, the flexible elastic seat frame 40a and the fabric seat cover 72a cooperate to form an upholstery cover or cover assembly 100a. Specifically, the side edges 43a of the seat frame 40a and the side edges 77a of the seat cover 72a, the front edge 45a of the seat frame 40a and the front edge 73a of the seat cover 72a, and the rear edge 47a of the seat frame 40a and the rear edge 75a of the seat cover 72a are respectively joined together to form a cover or cover 100a and to define an interior space 102a therein. The flap portion 49a of the seat frame 40a includes a pair of corner edges 104a, each extending along a corner 106a of the seat frame 40a located between the rear portion 44a and the respective side portions 42a, such that the flap portion 49a is movable between an open position I and a closed position J. In the illustrated example, each corner edge 104a of the flap portion 49a includes a plurality of tabs 108a spaced along the corner edge 104a, each of which includes an opening 110a extending through it. The tabs 108a of the corner edge 104a are separated from each other by a plurality of tabs 112a spaced along the corner edge 114a of each side portion 42a. Each of the 112a tabs includes an opening 116a that extends across it.The seat frame 40a also includes a plurality of integrally molded coupling lugs 118 spaced around an inner rim 121a of the seat frame 40a and each of which has a Z-shaped cross-section configuration. In the assembly, the upholstery cover assembly 100a (Figure 9) is constructed from the seat frame 40a and seat cover 72a as described above. The seat tub 46a, cushion member 70a, and spring support assembly 78a are then arranged relative to each other mounted on the upholstery cover assembly 100a by placing flap 49a in the open position I, positioning the seat tub 46a, cushion member 70a, and spring support assembly 78a within the inner space 102a, and then moving flap 49a to the closed position J. A pair of quick-connect fasteners 120a each includes a plurality of snap or press couplers 122a spaced along the entire length of the L-shaped body portion 124a.In assembly, the snap or press couplers 122a extend through the openings 110a, 116a of the tabs 108a, 112a, and are received under pressure within the corresponding openings 126a of the seating trough 46a, thereby securing the corner edges 104a, 114a to the trough of 46a to the flap portion 49a in the closed position J. Furthermore, during assembly, the coupling tabs 118a (Figure 10) are placed within the corresponding openings 130a of the seat tray 46a, thereby allowing manipulation Additional securing of the seat liner assembly 160a during assembly, while maintaining the connection and alignment of the liner assembly 100a with the seat tray 46a. As used herein, “temporarily securing” is defined as securing without expecting to maintain the securing of the liner assembly 100a to the seat tray 46a itself during normal use of the seat assembly through the normal service life of the seat assembly. The support plate 32a is then secured to a lower side of the seat tray 46a by means of a plurality of screws 132a, thereby sandwiching the mating tabs 118 between the support plate 32a and the seat tray 46a, and permanently securing the liner assembly 100a to the seat tray 46a.As used herein, “permanently secure” is defined as the securing that is expected to maintain the security of the liner assembly to the seat tub 46a during normal use of the chair assembly through the normal service life of the chair assembly. The numerical reference 16b (Figure 11) generally designates another seat assembly configuration. Since seat assembly 16b is similar to the previously described seat assemblies 16 and / or seat assembly 16a, the similar parts shown in Figures 5A-10 and Figures 11-17, respectively, are represented by the same corresponding reference number, except for the suffix “b” in the latter numbers. In the illustrated example, seat assembly 16b is similar in configuration and construction to seat assembly 16 and seat assembly 16a, the most notable exception being an external seat frame 40b, configured and constructed alternatively 40b, and the upholstery cover 100b. The seat assembly 16b (Figure 11) includes a flexible, elastic external seat frame 40b having a pair of upward-turned side portions 42b, each terminating in a side rim 43b, a front rim 45b, and an upward-turned rear portion 44b terminating in a rear rim 47b, where the side portion 42b and the rear portion 44b cooperate to form a generally upward-facing, concave, three-dimensional shape. The seat frame 40b is comprised of a relatively flexible material such as a thermoplastic elastomer (TPE) and is molded as a single, integral piece.In the assembly, described in more detail below, the external seat frame 40b is secured and sandwiched between the support portion 32b, a flexible and elastic plastic seat tray 46b, and a substantially rigid plastic top liner 51b, each of which is secured to the seat support plate 32b by a plurality of mechanical fasteners. The top liner or layer 51b is shaped to curve upwards and includes a top wall 53b and a pair of forward-extending side walls 55b, each of which includes a front rim 57b, and where the rear wall 53b and the side walls 55b cooperate to form a further top rim 59b.The seat basin 46b includes a front rim 48b, a rear rim 50b, side rims 52b extending between the front rim 48b and the rear rim 50b, a top surface 54b and a bottom surface 56b that cooperate to form a generally concave shape positioned upwards. As best illustrated in Figures 12 and 13, the flexible elastic seat frame 40b, the fabric seat cover 72b, and the lining or top layer 51b cooperate to form the upholstery or cover assembly 100b. In the illustrated example, the side edges 43b of the seat frame 40b and the side edges 77b of the seat cover 72b, the front edge 45b of the seat frame 40b and the front edge 73b of the seat cover 72b, and the rear edge 47b of the seat frame The seat frame 40b and the rear edge 75b of the seat cover 72b are joined together, respectively, so that the seat frame 40b and the strip seat cover 72b cooperate with the top layer cover 51b to form the cover 100b and to define an interior space 102b therein. The seat frame 40b also includes a plurality of integrally molded coupling tabs 118b spaced around an inner edge 121b of the seat frame 40b and each having a Z-shaped cross-sectional configuration. In assembly, the seat frame 40b (Figure 14) and the seat cover 72b of the upholstery cover 100b are mated together as previously described. As further illustrated in Figures 15 and 16, the side portions 42b of the seat frame 40b are mated to the fabric seat cover 72b to define a corner 79b between them. It should be noted that both the fabric material and the fabric seat cover 72b, as well as the TPE of the seat frame 40b, provide an aesthetically pleasing, sharp corner angle β of 90° or less, while simultaneously providing a deformable, elastic, and soft feel to the user. The seat tray 46b, cushion member 70b, and spring support assembly 78b are then arranged relative to each other and positioned within the interior space 102b of the cover 100b.The frame 40b is then secured to a seat tray 46b for lateral displacement by means of a plurality of integral hook-shaped couplers 123b spaced around the periphery of a frame 40b and one portion of which engages for each downward-extending portion 125b extending around the lateral and rear periphery of the seat tray 46b. The frame 40b (Figure 17) further includes a plurality of Z-shaped couplers 127b integrated with the frame 40b and received within corresponding openings 129b of the seat tray 46b, thereby temporarily securing the frame 40b to the seat tray 46b with respect to vertical displacement. Furthermore, in the assembly, the top liner 51b (Figure 17) includes a plurality of integrally formed L-shaped hooks 131b spaced along the side walls 55b and slidingly engaged with a corresponding plurality of angled couplers 133b integrally formed with the seat tray 46b. Specifically, the hooks 131b engage with the couplers 133b when the top liner 51b slides forward relative to the seat tray 46b. The lining or layer 51b is then secured in place by means of a pair of screws 135b that extend through corresponding openings 137b of the lining or top layer 51 and are threaded into corresponding projections or lugs 139b of the seating trough 46b, thereby capturing the couplers 127b within the openings 129b.The support plate 32b is then secured to the inside of the seat tray 46b by means of a plurality of screws 132b, thereby sandwiching a plurality of separate coupling tabs 141b integrated with the top lining 51b between the support plate 32b and the seat tray 46b, and permanently securing the cover assembly 100b to the seat tray 46b. It should be noted that the terms “temporarily secure” and “permanently secure” are defined above herein. The reference number 16b' (Figure 11A) generally designates another seat assembly configuration. Since seat assembly 16b' is similar to the previously described seat assembly 16b, the similar parts shown in Figure 11 and Figure 11A respectively are represented by the same reference number. RRQQnn / LZnZ / E / Yli corresponding reference number, except for the suffix in the latter numbers. In the illustrated example, seat assembly 16b' is similar in configuration and construction to seat assembly 16b, with the most notable exception being an alternatively configured foam cushion member 70b'. Cushion member 70b' includes a first portion 81b' and a second portion 83b'. In the assembly, the first portion 81b' of cushion member 70b' is placed over the seat tray 46b'. The connecting member 84b' is secured to a lower side of the seat tray 46b' by means of mechanical fasteners such as screws (not shown). The second portion 83b' of the cushion member 70b' is then wrapped around the front edge 48b' of the seat tub 46b' and the joining member 84b', and secured to the joining member 84b' by means of an adhesive.The combination of the seat tray 46b', the cushion member 70b' and the joining member 84b' is joined with the seat support plate 32b', to which the spring members 88b' are pre-attached, and the linear bearing 96b' is attached to it. The backrest assembly 18 (Figures 18-20B) includes a backrest frame assembly 200 and a backrest support assembly 202 supported by it. The backrest frame assembly 200 is generally comprised of a substantially rigid material such as metal, and includes a laterally extending upper frame portion 204, a laterally extending lower frame portion 206, and a pair of curved side frame portions 208 that extend between the upper frame portion 204 and the lower frame portion 206 and cooperate with it to define an opening 210 having a relatively large upper dimension 212 and a relatively narrow lower dimension 214. The backing assembly 18 further includes a flexible, elastic plastic backing frame 216 having an upper portion 218, a lower portion 220, a pair of side edges 222 extending between the upper portion 218 and the lower portion 220, a forward-facing surface 224, and a rearward-facing surface 226, wherein the width of the upper portion 218 is generally greater than the width of the lower portion 220, and the lower portion 220 tapers downward generally following the rearward-raised configuration of the frame assembly 200. A lower reinforcing member 228 (Figure 29A) is attached to hooks 230 of the lower portion 220 of the backing frame 216.The reinforcing member 228 includes a plurality of projections 232 that engage with a plurality of reinforcing flanges 250 of the backing frame 216 to prevent side-to-side movement of the lower reinforcing member 228 relative to the backing frame 216, while the reinforcing member 228 rotatably interconnects the backing control link 236 to the lower portion 220 of the backing frame 216 at a pivot point or axis 590, each as described below. The backing frame 216 also includes a plurality of integrally molded hooks extending forward and upward 240 (Figure 21) spaced around the periphery of the upper portion 218 thereof. An intermediate or lumbar portion 242 is located vertically between the upper portion 218 and the lower portion 220 of the backing frame or lining 216, and includes a plurality of laterally extending grooves 244 that cooperate to form a plurality of laterally extending flanges 246 located between them. The grooves 244 cooperate to position and drive the backing frame or lining 216 into place. Pairs of lateral flanges 246 are coupled by vertically extending flanges 248 formed integrally with them and located at a near lateral midpoint. The vertical flanges 248 function to fasten the The lateral flanges 246 reduce the vertical separation between them when the backrest frame 216 flexes to the intermediate portion 242 thereof when the backrest assembly 18 is displaced from the upright position E to the reclined position F, as described below. The plurality of laterally separated reinforcing flanges 250 extends longitudinally the entire length of the backrest frame 216 between the lower portion 220 of the intermediate portion 242. It should be noted that the depth of each of the flanges 250 increases along each of the flanges 250 of the intermediate portion 242 towards the lower portion 220, so that the overall stiffness of the backrest frame 216 is increased along the entire length of the flanges 250. The backrest frame 216 (Figures 20A and 20B) further includes a pair of integrally molded, rearward-extending pivot lugs 252 that are part of an upper backrest pivot assembly 254. The backrest pivot assembly 254 (Figures 22-24B) includes the pivot lugs 252 of the backrest frame 216, a pair of annular reinforcing members 256 spanning the respective pivot lugs 252, a grooved member 258, and a mechanical clamping assembly 260. Each pivot lug 252 includes a pair of side walls 262 and a rearward-facing, joined seating surface 264 having a vertically elongated pivot groove 266 extending through it.Each annular reinforcing member 256 is formed to closely accommodate the corresponding pivot projection 252, and includes a plurality of side walls 268 corresponding to the side walls 262, and a rearward-facing concave elbow and bearing surface 270 including a vertically elongated pivot groove 272 extending through it, and adapted to align with the groove 266 of a corresponding pivot projection 252. The grooved member 258 includes a center portion 274 that extends laterally and splices to the upper frame portion 204 of the backup frame assembly 200 and a pair of arcuate bearing surfaces 276 located at the ends thereof.Specifically, the center portion 274 includes a first portion 278 and a second portion 280 where the first portion 278 is spliced ​​to a front surface of the upper frame 204 and the second portion 280 is spliced ​​to a top surface of the upper frame portion 204. Each bearing surface 276 includes an opening 282 extending through it and aligning with a corresponding raised member 284 integrated into the backing frame assembly 200. In the assembly, the annular reinforcing members 256 are positioned around the corresponding pivot projection 252 of the backing frame 216 and operatively positioned between the backing frame 216 and the grooved member 258, so that the bearing surface 270 is sandwiched between the seating surface 264 of a corresponding pivot projection 252 and a bearing surface 276. The mechanical clamping assemblies 260 each include a bolt 286 that secures a rounded splice surface 288 of a bearing washer 290 and a slip-on coupling with a lower surface 292 of the corresponding pivot projection 252, and which thread-fits the corresponding raised member 284 of the backing frame 216.In operation, the upper backup pivot assembly 254 allows a backup support assembly 202 to rotate with respect to the backup frame assembly in a direction 294 (Figure 19) about a pivot axis 296 (Figure 18). The backrest support assembly 202 (Figures 20A and 20B) further includes a flexible, elastic comfort member 298 (Figures 26A and 26B) attached to the backrest frame 216 and supported by sliding. RRQQnn / LZnZ / E / Yli a lumbar assembly 300. The comfort member 268 includes an upper portion 302, a lower portion 304, a pair of side portions 306, a front surface 308 and a back surface 306, wherein the upper portion 302, the lower portion 304 and the side portions 306 cooperate to form an opening 312 that receives the lumbar assembly 300 therein. As best illustrated in Figures 20B and 25, the comfort member 298 includes a plurality of box-shaped couplers 314 spaced around the periphery of the upper portion 302 and extending rearward from the rear surface 310. Each box-shaped coupler 314 includes a pair of side walls 316 and a top wall 318 cooperating to form an interior space 320. A rod 322 extends between the side walls 316 and is separate from the rear surface 310.In assembly, the comfort member 398 is secured to the backrest frame 216 by aligning and vertically inserting the hooks 240 (Figure 23) of the backrest frame 216 into the inner space 320 of each of the box-shaped couplers 314 until the hooks 340 engage a corresponding rod 322. It should be noted that the front surface 224 of the backrest frame 216 and the rear surface 310 and the comfort member 398 are free of holes or openings near the hooks 240 and the box-shaped couplers 314, thereby providing a smooth front surface 308 and increasing the comfort of a seated user. The comfort member 298 (Figures 26a and 26B) includes a longitudinally extending, integrally molded sleeve 324 that extends posteriorly from the posterior surface 310 and has a rectangular cross-sectional configuration. The lumbar assembly 300 includes a laterally flexible, forward-concave, vertically forward-convex, elastic body portion 326, and an integral support portion 328 that extends upward from the body portion 326. In the illustrated example, the full body portion 326 is formed so that the body portion is worn vertically along its length to generally follow the contours and shapes of the opening 312 of the comfort member 298.The support portion 328 is slidably received within the sleeve 324 of the comfort member 298, so that the lumbar assembly 300 is vertically adjustable relative to the rest of the backrest support assembly 202 between a fully lowered position I and a fully raised position J. A ratchet member 330 selectively engages a plurality of openings 332 spaced along the entire length of the support portion 328, thereby releasably securing the lumbar assembly 300 in selected vertical positions between the fully lowered position I and the fully raised position J. The ratchet member 330 (Figures 27A and 27B) includes a housing portion 334 having engagement tabs 336 located at its ends and offset rearward from an external surface 338 of the housing portion 334.A flexible, elastic finger 340 is positioned in the center within the housing portion 334 and includes a rearward-extending ratchet 342. In the assembly, the ratchet member 330 (Figure 28) is placed within an opening 344 located within the upper portion 302 of the comfort member 298, such that the outer surface 338 of the housing portion 334 of the ratchet member 230 is coplanar with the front surface 304 of the comfort member 298, and such that the coupling tabs 336 of the housing portion 334 engage with the surface 310 of the comfort member 298. The support portion 328 of the lumbar assembly 300 is placed within the sleeve 324 of the comfort member 288, such that the The sleeve 324 slides into it and the ratchet 342 is selectively engageable with the openings 332, thereby allowing the user to optimize the position of the lumbar mount 300 with respect to the overall back support mount 202. Specifically, the body portion 326 of the lumbar mount 300 includes a pair of lower handle portions extending towards some 346 (Figures 29A and 29B), each of which has a C-shaped cross-sectional configuration defining a channel 348 therein and running around a guide along the respective side edge 200 of the back frame 226. Alternatively, the lumbar mount 300c (Figure 30) is provided where the body portion 326c and the support portion 328 are integrally formed, and the handles 346c are formed separately from the body portion 326b and join to it.In the alternative embodiment, each handle 346c includes a pair of guides or blades 350 received within corresponding receptacles 352c of the body portion 326c. Each blade 350c includes a pair of pressure tabs 354c spaced along its entire length and press-fitted to an edge of one of a plurality of openings 356c within the body portion 326c. In operation, a user adjusts the relative vertical position of the lumbar assembly 300, 300c with respect to the backrest frame 216 by grasping one or both handle portions 346, 346c and sliding the handle assembly 346, 346c along the comfort member 289 and backrest frame 298 in a vertical flexion. A stop tab 358 is integrally formed within a distal end 360 and deflects therefrom to engage an end wall of the cuff 324 of the comfort member 298, thereby limiting the downward vertical displacement of the support portion 328 of the lumbar assembly 300 with respect to the cuff 324 of the comfort member 298. The backrest assembly 202 (Figures 20A and 20B) further includes a cushion member 362 having an upper portion 364 and a lower portion 366, wherein the lower portion 366 is used along its vertical length to correspond to the overall throw shape of the backrest frame 216 and the comfort member 298. The backrest support assembly 202 further includes an upholstery cover assembly 400 (Figure 31) that houses the comfort member 298, the lumbar support assembly 300, and the cushion member 362. In the illustrated example, the cover assembly 400 comprises a fabric material and includes a front side 402 (Figure 32A) and a back side 404 that are sewn together along their respective side edges to form a first pouch or sack 406 having a first interior or inner space 408 that receives the comfort member 298 and the cushion member 362, and a flap portion 410 that is sewn to the back side 404 and cooperates with it to form pouches or sacks 412 having a second interior space 403 (Figure 32D) that receive a lumbar support assembly 300. In the assembly, the first receptacle 406 (Figure 32A) is formed by joining the respective side edges of the front side 402 of the positive side 404 together, either by stitching or other means suitable for the material, which comprises the upholstery assembly 400 and defines the first inner space 408. An edge of the flap portion 410 is then secured to a lower end of the back side 404. In the illustrated example, the combination of the back frame 216 and the cushion member 362 is then inserted into the inner space 408 and the first pocket or sack 406 via an opening 415 in the back side 404 (Figure 32B). The upholstery assembly 400 is stretched around the cushion member 362 and the comfort member 388 and secured to the comfort member 298 by means of a RRQQnn / LZnZ / E / Yli plurality of openings 420 receiving upwardly extending hook members 424 (Figure 33) through them. Alternatively, the cover assembly 400 can be configured so that the openings 420 are positioned to also receive the member of a T-shaped member 422 through them. In the illustrated example, the joining members 422 and the hook members 424 are integrally formed with the comfort member 298. Each joining member 422 is provided with a T-shaped cross-section or joining bracket configuration having a first portion 428 extending perpendicularly backward from inside a cavity or receptacle 429 of the rear surface 310 of the comfort member 298, and a pair of second portions 430 located at a distal end of the first portion 428 extending outward therefrom in opposite relation to each other.One of the second portions 430 cooperates with the first portion 428 to form an angled coupling surface 432. The cavity 439 defines a border 434 around its perimeter. The lining assembly 400 is further secured to the comfort member 298 by a pull strap 436 that extends through a pull strap tunnel 438 of the lining assembly 400 and is secured to member 422. Specifically, and as best illustrated in Figures 34A-34H, each free end of the pull strap 436 is secured to an associated joining member 422 without knots and without the use of a mechanical fastener that is separate from the comfort member 298. In the assembly, the pull strap 436 and pull strap tunnel 238 guide around a plurality of guide hooks 439 (Figure 26B) located around a periphery of and integrally formed with the comfort member 298.The traction belt 436 is wound around the associated connecting member 422, such that the tension in the traction belt 436 around the connecting member 422 forces the traction belt 436 against the mating surface 432 that is angled toward the cavity 429, thereby forcing a portion of the traction belt 436 into the cavity 429 and into the coupling with at least a portion of the edge 434 of the cavity 429, resulting in a friction coupling between the traction belt 436 and the comfort member 228. Figures 35G and 35H illustrate alternative paths that the traction belt 436 can take around the connecting member 422 relative to the steps illustrated in Figures 34B and 34H, respectively. The lumbar assembly 300 (Figure 32C) is then aligned with the lining assembly 400, the cushion member 362, and the comfort member 298, such that the body portion 326 of the lumbar assembly 300 is located near a midsection 414 of the lining assembly 400, and the support portion 328 of the lumbar assembly 300 engages with the comfort member 298, as described above. The flap portion 410 (Figure 32D) is then folded over a lumbar assembly 300, thereby creating a second pouch or bag 412 having an interior space 413. A distally located rim 442 of the flap portion 410 is joined to the comfort member 298 by means of a plurality of openings 444 within the flap portion 410, which receive hooks 424 through them. The distal edge 442 can also be sewn to the back side 404 of the cover assembly 400.In the illustrated example, the side edges 446 of the flap portion 410 do not join the rest of the cover assembly 400, so that the side edges 446 cooperate with the rest of the lining assembly 400 to form grooves 448 through which the handle portion 346 of the lumbar assembly 300 extends. The second pouch or bag 412 is configured so that the lumbar assembly 300 fits vertically into it. RRQQnn / LZnZ / E / Yli cover assembly 400, cushion member 362, comfort member 298 and lumbar assembly 300 are then joined to the backrest frame 216. The reference number 18d (Figure 36) generally designates an alternative form of the backrest assembly. Since backrest assembly 18d is similar to the previously described backrest assembly 18, the similar parts shown in Figures 20A and 20B and Figures 36–41 are represented, respectively, by the same corresponding reference number, except for the suffix “d” in the latter numbers. Backrest assembly 18d includes a backrest frame assembly 200d, a backrest frame 216d, and a trim assembly 400d. In the illustrated example, the backrest frame 216d includes a substantially flexible outer peripheral portion 450d (Figures 37 and 38) and a substantially less flexible rear portion 452d to which the peripheral portion 450d is attached.The rear portion 452d includes a plurality of vertically spaced, laterally extending grooves 454d that cooperate to define slats 456d between them. The peripheral portion 450d and the rear portion 452d cooperate to form an outward-facing opening 458d that extends around the periphery of the backing frame 216d. The rear portion 452d includes a plurality of spaced flanges 460d around the opening 458d and are used to secure the sheathing 400d to the backing frame 216d as described below. The lining assembly 400d includes a fabric lining 462d and a resting member 464d extending around the peripheral edge 466d of the fabric lining 462d. The fabric lining 462d includes a front surface 468d and a rear surface 470d and preferably comprises a flexible material in at least one longitudinal and one lateral direction. As best illustrated in Figure 39, the reinforcing member 464d is annular in shape and includes a plurality of enlarged portions 472d, each having a rectangular cross-sectional configuration, separated from each other by a plurality of tapered corner portions 474d, each having a circular cross-sectional configuration.Each of the enlarged portions 472d includes a plurality of openings 476d spaced along its entire length and adapted to engage with the flanges 460d of the backing frame 216d, as described below. The annular reinforcing member 464d is comprised of a relatively flexible plastic so that the annular reinforcing member 464d can be rotated from the inside out, as illustrated in Figure 40. In the assembly, the annular reinforcing member 464d is secured to the back surface 470d of the lining 462d so that the lining 462d is fixed to rotate with the enlarged portions 472d, and so that the lining 462d is fixed to rotate with the narrowed corner portions 474d along a line tangential to a longitudinal axis of the narrowed corner portions 474d. In the present example, the annular reinforcing member 464d (Figure 41) is stitched around the peripheral edge 466d of the lining 462d by a stitch pattern that extends across the enlarged portions 472d and around the narrowed corner portions 474d. In the present example, the annular reinforcing member 464d (Figure 41) is stitched around the peripheral edge 466d of the lining 462d in the stitch pattern that extends across the enlarged portions 472d and around the narrowed corner portions 464d.The cladding assembly 400d and the cladding 462d and the annular reinforcing member 464d are aligned with a backing frame 216d and the peripheral edge 466d of the cladding 462d. RRQQnn / LZnZ / E / Yli is wound around the backing frame 216d so that the annular reinforcing member 464d is turned inside out. The annular reinforcing member 464d is then inserted into the opening or groove 458d, so that the tension of the fabric lining 462 being stretched around the backing frame 216d causes the annular reinforcing member 464d to remain positively engaged within the groove 458d. The flanges 460d of the backing frame 216d engage with the corresponding openings 476d of the annular reinforcing member 464d, thereby further securing the annular reinforcing member 464d within the groove 458d.It should be noted that the stitching pattern joining the lining 462 to the annular reinforcing member 464d allows the narrowed corner portions 474d of the annular reinforcing member 464d to rotate freely with respect to the lining 462d, thereby reducing the occurrence of aesthetic anomalies near the corners of the lining 462d, such as warping or overstretching of a given fabric pattern. The seat assembly 16 and the backrest assembly 18 are operatively coupled and controlled by the control assembly 14 (Figure 42) and a control input assembly 500. The control assembly 14 (Figures 43-45) includes a housing or base structure or floor structure 502 comprising a front wall 504, a rear wall 506, a pair of side walls 508, and a bottom wall 510 integrally formed with each other and cooperating to form an interior space opening upwards 512. The bottom wall 510 includes an opening 514 positioned in its center, as described below. The base structure 502 further defines an upper forward pivot point 516, a lower rearward pivot point 518, and an upper rearward pivot point 540, wherein the control assembly 14 further includes a seat support structure 522 that supports the seat assembly 16.In the illustrated example, the seat support structure 522 has a generally flat LJ-shaped configuration that includes a pair of forward-extending arm portions 524, each of which includes a forward-located pivot opening 526 rotatably secured to the base structure 502 by a pivot shaft 528 for rotational movement about the upper pivot point and forward 516. The seat support structure 522 further includes a rear portion 530 that extends laterally between the arm portions 524 and cooperates with them to form an interior space 532 within which the base structure 502 is received. The rear portion 530 includes a pair of rearward-extending arm mounting portions 534 to which the arm mounts 20 are attached as described below.The seat support structure 522 further includes a mounting portion for the control input assembly 536 to which a control input assembly 500 is mounted. The seat support structure 522 further includes a pair of bushings 538 that cooperate to define the pivot point 540. The control assembly 14 further includes a back support structure 542, which, in plan view, is generally U-shaped. This structure includes a pair of forward-extending arm portions 544, each of which includes an opening 546 and is rotatably coupled to the base structure 502 by a pivot axis 548, such that the back support structure 542 rotates about the lower pivot point and forward 518. The back support structure 542 includes a rear portion 550 that cooperates with the arm portions 544 to define an interior space 552, which receives the base structure 502. The back support structure 542 further includes a pair of pivot openings 554 located along its entire length, which cooperate to define a pivot point. RRQQnn / LZnZ / E / Yli pivot 556. It should be noted that, in certain cases, at least a portion of the backrest frame assembly 200 may be included as part of the backrest support structure 542. The control assembly 14 further includes a plurality of control links 558, each of which has a first end 560 rotatably coupled to the seat support structure 522 by means of a pair of pivot bolts 562 to rotate about the pivot point 540, and a second end 564 rotatably coupled to the corresponding pivot openings 554 of the backrest support structure 542 by means of a pair of pivot bolts 566 to rotate about the pivot point 556. In operation, the control links 558 control the movement, and specifically the reclining speed, of the seat support structure 522 with respect to the backrest support structure 542 when the chair assembly is moved to the reclined position, as described below. As best illustrated in Figures 46A and 46B, the lower frame portion 206 of the backup frame assembly 200 is configured to connect to the backup support structure 542 via a quick-connect arrangement 568. Each arm portion 544 of the backup support structure 542 includes a mounting opening 570 located at a near end 572 thereof. In the illustrated example, the quick-connect arrangement 568 comprises a configuration of the lower frame portion 206 of the backup frame assembly 200 that includes a pair of forward-extending coupler portions 574 that cooperate to define a channel 576 between them that receives the rear portion 550 and the near ends 572 of the arm portions 544 therein. Each coupler portion 574 includes a downward-extending projection 578 that aligns with a received guide within a corresponding opening 570.Mechanical fasteners, such as screws 580, are then threaded into the projections 578, thus allowing a quick connection of the backup frame assembly 200 to the control assembly 14. As best illustrated in Figure 47, the base structure 502, the seat support structure 522, the backrest support structure 542, and the control links 558 cooperate to form a 4-rod link assembly that supports the seat assembly 16, the backrest assembly 18, and the arm assemblies 20 (Figure 1).For ease of reference, the associated pivot assemblies in the 4-rod link assembly of control assembly 14 are referred to as follows: the upper forward pivot point 516 between the base structure 502 and the base support structure 522 as the first pivot point 516; the lower forward pivot point 518 between the base structure 502 and the backrest support structure 542 as the second pivot point 518; the pivot point 540 between the first end 560 of the control link 558 and the seat support structure 522 as the third pivot point 540; and, the pivot point 556 between the second end 564 of the control link 558 and the backrest support structure 542 as the fourth pivot point 556. In addition, Figure 47 illustrates the chair assembly component 10 shown in a reclined position in dashed lines where the chair reference numbers in the reclined position are designated with a. In operation, the 4-rod link assembly of control assembly 14 cooperates to recline seat assembly 16 from the upright position E to the reclined position H when backrest assembly 18 is moved from upright position E to reclined position F, where the upper and lower representations of positions E and F in Figure 47 illustrate that the upper and lower portions of backrest assembly 18 recline as a single unit. Specifically, control link 558 is configured and coupled to the RRQQnn / LZnZ / E / Yli seat support structure 522 and backrest support structure 542 to make the seat support structure 522 rotate around the first pivot point 516 when the backrest support structure 542 rotates around the second pivot point 518.Preferably, the seat support structure 522 rotates about the first pivot point 516 between approximately 1 / 3 and approximately 2 / 3 of the rotation speed of the backrest support structure 542 about the second pivot point 518; more preferably, the seat support structure 522 rotates about the first pivot point 516 at approximately the rotation speed of the backrest support structure 542 about the second pivot point 518; and more preferably, the seat assembly 16 reclines to an angle β of approximately 9° from the fully upright position G to the fully reclined position H, while the backrest assembly 18 reclines to an angle β of approximately 18° from the fully upright position E to the fully reclined position F. As best illustrated in Figure 47, the first pivot point 516 is located above and in front of the second pivot point 518 when the chair assembly 10 is in the fully upright position, and when the chair assembly 10 is in the fully reclined position, when the base structure 502 remains fixed relative to the supporting floor surface 13 as the chair assembly 10 is reclined. The third pivot point 540 remains behind and below the relative vertical height of the first pivot point 516 throughout the reclining movement of the chair assembly 10. It should also be noted that the distance between the first pivot point 516 and the second pivot point 518 is greater than the distance between the third pivot point 540 and the fourth pivot point 556 throughout the reclining movement of the chair assembly 10.As best illustrated in Figure 48, a longitudinally extending centerline axis 582 of the control link 558 forms an acute angle α with the seat support structure 522 when the chair assembly 10 is in the fully upright position and an acute angle α' when the chair assembly 10 is in the fully reclined position. It should be noted that the centerline axis 582 of the control link 558 does not rotate along an orthogonal alignment with the seat support structure 522 when the chair assembly 10 moves between its fully upright and fully reclined positions. With further reference to Figure 49, a backrest control link 584 includes a front end 585 rotatably attached to the seat support structure 522 at a fifth pivot point 586. A rear end 588 of the backrest control link 584 connects to the lower portion 220 of the backrest frame 216 at a sixth pivot point 590. The sixth pivot point 590 is optional, and the backrest control link 584 and the backrest frame 216 may be rigidly fixed to each other. Also, the pivot point 590 may include a stop element that limits the rotation of the backrest control link 584 relative to the backrest frame 216 in a first and / or second rotational direction.For example, with reference to Figure 49, the pivot point 590 may include a stop element 592 that allows clockwise rotation of the lower portion 220 of the backrest frame 216 relative to the control link 584. This allows the lumbar portion to flatten if a rearward / horizontal force is applied that tends to reduce dimension D1 to the lumbar portion of the backrest frame 216. However, the stop element 592 may be configured to prevent counterclockwise rotation of the lower portion 220 of the backrest frame 216. RRQQnn / LZnZ / E / Yli (Figure 49) with respect to control link 584. This causes control link 584 and the lower portion 220 of the backrest frame 216 to rotate at the same angular velocity when a user reclines in the chair pushing against an upper portion of the backrest assembly 18. A cam link 594 is also rotatably coupled or connected to the seat support structure 522 to rotate about the pivot point or axis 586. The cam link 594 has a curved lower cam surface 596 that slidably engages with an upwardly facing cam surface 598 formed in the backrest support structure 542. A pair of torsion springs 600 (see also Figure 29A) rotatably deflects the backrest control link 584 and the cam link 594 in such a way as to tend to increase angle θ (Figure 49). The torsion springs 600 generate a force that tends to rotate the control link 584 counterclockwise and simultaneously rotate the cam link 594 clockwise. Thus, the 600 torsion springs tend to increase the angle 0 between the backup control link 584 and the cam link 594.The stop element 592 in the seat support structure 522 limits the counterclockwise rotation of the backrest control link 584 to the position shown in Figure 49. This force can also deflect the control link 584 in a counterclockwise direction toward the stop element 592. As discussed earlier, the backrest frame 216 is flexible, particularly compared to the rigid backrest frame structure 200. Also discussed earlier, the backrest frame structure 200 is rigidly connected to the backrest support structure 542 and therefore rotates with it. The forces generated by the torsion springs 600 push upward against the lower portion 220 of the backrest frame 216. As also discussed earlier, the slots 244 in the backrest frame structure 216 create additional flexibility in the lumbar support portion or region 242 of the backrest frame 216. The force generated by the torsion springs 600 also tends to cause the lumbar portion 242 of the backrest frame 216 to bend forward, resulting in a greater curvature of the lumbar portion 242 than the regions adjacent to the torsion springs 600. As discussed previously, the position of lumbar mount 300 is vertically adjustable. The vertical adjustment of lumbar mount 300 also affects how backrest frame 216 flexes / curves during chair backrest reclining. For example, when lumbar mount 300 is set to a neutral or intermediate position, the curvature of lumbar portion 342 (Figure 49) of backrest frame 216 is also in a lumbar or intermediate position. If the vertical position of lumbar mount 300 is adjusted, angle 0 (Figure 50) decreases, and the curvature of lumbar portion 242 is reduced. As shown in Figure 50, this also increases angle 01, making the overall shape of backrest frame 216 relatively flat. With further reference to Figure 51, if the height of lumbar assembly 300 is set at an intermediate level (i.e., as in Figure 49), and the user reclines, the 4-rod linkage defined by links and structures 502, 522, 542, 558 and pivot points 516, 518, 540, 556 will deviate (as described above) from the configuration in Figure 49 to the configuration in Figure 51. This, in turn, causes an increase in the distance between pivot point 586 and cam surface 598. This causes RRQQnn / LZnZ / E / Yli an increase in angle 0 from approximately 49.5° (Figure 49) to approximately 59.9° (Figure 51). When the spring rotates to an open position, some of the energy stored in the spring is transferred to the frame 216, thereby causing the degree of curvature of the lumbar portion 220 of the backrest frame 216 to become greater. In this way, the backrest control link 584, the cam link 594, and the torsion springs 600 provide a greater curvature of the lumbar portion 242 to reduce the curvature of a user's back when the user reclines in the chair. Also, when the chair is tilted from the position in Figure 49 to the position in Figure 51, the distance D between the lumbar region or portion 242 and the seat 16 increases from 174 mm to 234 mm. A dimension D1 between the lumbar portion 242 of the backrest frame 216 and the backrest frame structure 200 also increases when the backrest 18 is tilted from the position in Figure 49 to the position in Figure 51. Thus, although the distance D increases somewhat, the increase in dimension D1 reduces the increase in dimension D because the lumbar portion 242 of the backrest frame 216 is displaced forward relative to the backrest frame 200 during reclining. Referring again to Figure 49, the spine 604 of a seated user 606 tends to curve forward in the lumbar region 608 to an initial degree when the user 606 sits in an upright position. When the user 606 reclines from the position in Figure 49 to the position in Figure 51, the curvature of the lumbar region 608 tends to increase, and the spine of the user 604 will also rotate somewhat around the hip joint 610 relative to the user's femur 612. The increase in dimension D and the increase in curvature of the lumbar portion 242 of the backrest frame 216 simultaneously ensures that the user's hip joint 610 and femur 612 do not slide on the seat 16, and also accommodates the curvature of the lumbar region 608 of the spine of a user 604. As described above, Figure 50 shows the chair backrest 18 in an upright position with the lumbar portion 242 of the backrest frame 216 adjusted to a flat position. If the chair backrest 18 is tilted from the position in Figure 50 to the position in Figure 52, the backrest control link 584 and the cam link 594 both rotate clockwise. However, the cam link 594 rotates at a slightly higher speed, and the angle θ therefore changes from 31.4° to 35.9°. The distance D changes from 202 mm to 265 mm, and the angle θi changes from 24.2° to 24.1°. With further reference to Figure 52A, if the backrest of chair 18 is reclined, and the lumbar adjustment is set high, angle 0 is 93.6°, and distance D is 202 mm. Thus, the backrest frame 216 curves when the chair back 18 is tilted backward. However, the increase in curvature in the lumbar portion 242 from the upright to the reclined position is significantly greater if the curvature is initially set to a higher level. This contributes to the fact that the curvature of a user's back does not increase as much when the user reclines if the user's back is initially in a relatively flat position when sitting upright. In other words, if the user's back is relatively straight when in an upright position, the user's back will remain relatively flat even when reclined, even if the degree of curvature increases somewhat from the upright to the reclined position. Conversely, if a user's back curves significantly when in the upright position, the curvature of the lumbar region will increase. RRQQnn / LZnZ / E / Yli will increase to a greater degree when the user reclines relative to the increase in curvature if the user's back is initially relatively flat. A pair of spring assemblies 614 (Figures 43 and 44) ​​deflect the backrest assembly 18 (Figure 4) from the reclined position F to the upright position E. As further illustrated in Figure 45, each spring assembly 614 includes a cylindrical housing 616 having a first end 618 and a second end 620. Each spring assembly 614 further includes a compression coil spring 622, a first coupler 624, and a second coupler 626. In the illustrated example, the first coupler 624 is secured to the first end 618 of the housing 616, while the second coupler 626 is secured to a rod member 628 extending through the coil spring 622. A washer 630 is secured to a distal end of the rod member 628 and spliced ​​to one end of the coil spring. 622, while the opposite end of the helical spring 622 is spliced ​​to the second end 620 of the housing 616.The first coupler 624 is rotatably secured to the backing support structure 542 by a pivot pin 632 for pivoting movement about a pivot point 634, when the pivot pin 632 is received within the pivot openings 636 of the backing support structure 542, while the second coupler 626 is rotatably coupled to a deflection arm assembly 638 (Figures 53-55) by means of a shaft 644 for rotation about a pivot point 642. The deflection arm assembly 638 is adapted to move the spring deflection assembly 614 from a low-punch setting (Figure 57A) to a high-tension setting (Figure 58A) where the force exerted by a deflection assembly 614 on a backing assembly 18 is increased relative to the low-tension setting. As illustrated in Figures 53-56, the moment arm deflection assembly 638 includes an adjustment assembly 644, a moment arm deflection link assembly 646 that is operatively coupled to a control input assembly 500 and an adjustment assembly 644, enabling the operator to move the deflection assembly 614 between low and high tension settings, and an auxiliary adjustment assembly 648 that is adapted to reduce the amount of input force required to be exerted by the user on the control input assembly 500 to move the moment arm deflection assembly 638 from the low tension setting to the high tension setting, as described later. The adjustment assembly 644 comprises a pivot bolt 650 including a threaded opening that receives the threaded adjustment shaft 652. The adjustment shaft 652 includes at its first end 654 and a second end 656, wherein the first end 654 extends through the opening 514 of the base structure 502 and is guided to rotate about the longitudinal axis by a bearing assembly 660.The pivot pin 650 is supported from the base structure 502 by a link assembly 662 (Figure 44) which includes a pair of link arms and a joint 664, each of which has a first end rotatably coupled to the second coupler 626 by the pivot pin 632 and a second end 668 rotatably coupled to the base structure 502 by a pivot pin 670 rotatably received within a pivot opening 672 of the base structure 502 to rotate about a pivot point 674, and an opening 675 that receives a respective end of the pivot pin 650. The pivot pin 650 is rotatably coupled with the joint arms or link 664 along its length. The moment arm deflection link assembly 638 includes a first drive shaft 676 extending between the control input assembly 500 and a first chamfer gear assembly 678, RRQQnn / LZnZ / E / Yli and a second drive shaft 680 extending between and operatively coupled to a first chamfer gear assembly 678 with the second chamfer gear assembly 682, wherein the second chamfer gear assembly 682 is connected to the adjusting shaft 652. The first drive shaft 676 includes a first end 684 operatively coupled to the control input assembly 500 by means of a first joint or universal joint assembly 686, while the second end 688 of the first drive shaft 676 is operatively coupled to the first chamfer gear assembly 678 by means of a second joint or universal joint assembly 690.In the illustrated example, the first end 684 of the first drive shaft 676 includes a female coupling portion 692 of the first universal joint assembly 686, while the second end 688 of the first drive shaft 676 includes a female coupling portion 694 of the second universal joint assembly 690. The first bevel gear assembly 678 includes a housing assembly 696 that accommodates a first bevel gear 698 and a second bevel gear 700 therein. As illustrated, the first bevel gear 698 includes an integral male coupling portion 702 of the second universal joint assembly 690. The first end 706 of the second drive shaft 680 is coupled to the first bevel gear assembly 678 by means of a third universal joint assembly 704.The first end 706 of the second drive shaft 680 includes a female coupling portion 708 of the third universal joint or coupling assembly 704. The second bevel gear 700 includes an integral male coupling portion 710 of the third universal joint or coupling assembly 704. A second end 712 of the second drive shaft 680 includes a plurality of longitudinally extending grooves 714 that engage with corresponding longitudinally extending grooves (not shown) of a coupling member 716. The coupling member 716 couples the second end 712 of the second drive shaft 680 to the second bevel gear assembly 682 via a fourth universal joint or coupling assembly 718.The fourth universal joint or articulation assembly 718 includes a housing assembly 720 that accommodates a first chamfered gear 722 coupled to the coupler member 716 via a fourth universal joint or articulation assembly 718, and a second chamfered gear 724 fixed to the second end 656 of the adjusting shaft 652. The coupler member 716 includes a female coupler portion 726 that receives a male coupler portion 728 integrated to the first chamfered gear 722. In the assembly, the adjustment mount 644 (Figures 53 and 54) of the moment arm deflection assembly 638 is operatively supported by the base structure 502, while the control input mount 500 (Figure 42) is operatively supported by the portion of the control input mount 536 (Figure 44) of the seat support structure 522. As a result, the relative angles and distances between the control input mount 500 and the adjustment mount 644 of the moment arm deflection assembly 638 change when the support structure 522 is displaced between the fully upright position G and the fully reclined position H. The third and fourth universal joint or articulation mounts 704, 718, and the slot arrangement 714 and coupler 716 cooperate to compensate for these relative changes in angle and distance. The moment arm deflection assembly 638 (Figures 53 and 54) is used to adjust the deflection assemblies 614 between low-tension and high-tension settings (Figures 57A-58B). Specifically, the deflection assemblies 614 are shown in a low-tension setting with the assembly Figure 57A illustrates the deflection assemblies 614 in the high-tension setting with the chair assembly 10 in an upright position, and Figure 57B illustrates the deflection assembly 614 in the high-tension setting with the chair in an upright position. Figure 58A illustrates the deflection assembly 614 in the high-tension setting with the chair in the upright position, and Figure 58B illustrates the deflection assembly in the high-tension setting with the chair assembly 10 in the reclined position. The distance 730, measured between the pivot point 642 and the second end 620 of the spring assembly 614 housing 616, serves as a reference for the amount of compression exerted on the spring assembly 614 when the moment arm deflection assembly 638 is placed in the low-tension setting and the chair assembly 10 is in the upright position.The distance 730' (Figure 58A) comparatively illustrates the increase in the amount of compressive force exerted on the spring assembly 614 when the moment arm deflection assembly 638 is in the high-tension setting and the chair assembly 10 is in the upright position. The user adjusts the amount of force exerted by the deflection assemblies 614 on the backrest support structure 542 by moving the moment arm deflection assembly 638 from the low-tension setting to the high-tension setting.Specifically, the operator, through an input to the control input assembly 500, drives the adjustment shaft 652 of the adjustment assembly 644 into rotation via the moment arm deflection link assembly 646, thereby causing the pivot shaft 650 to move along the entire length of the adjustment shaft 654, thereby changing the compressive force exerted on the spring mounts 614 when the pivot shaft 650 is adjusted with respect to the base structure 502. The pivot shaft 650 moves within a groove 732 located within a side plate member 734 attached to an associated side wall 508 of the base structure 502.It should be noted that when the moment arm deflection assembly 638 is in the high-tension setting and the chair assembly 10 is in the upright position, distance 730' is greater than distance 730 when the moment arm deflection assembly 638 is in the low-tension setting and the chair assembly 10 is in the upright position, thus indicating that the compressive force exerted on the spring assemblies 614 is greater when the moment arm deflection is in the high-tension setting compared to the low-tension setting. Similarly, distance 736' (Figure 58B) is greater than distance 736 (Figure 57B), resulting in an increased deflection force exerted by the deflection assemblies 614 and forcing the backrest assembly 18 from the reclined position to the upright position.It should be noted that the change in deflection force exerted by the deflection mounts 614 corresponds to a change in the deflection torque exerted about the second pivot point 518, and that, in certain configurations, a change in deflection torque is possible without a change in the length of the deflection mounts 614 or a change in the deflection force. Figure 59 is a graph of the amount of torque exerted about the second pivot point 518 that forces the backrest support structure 542 from the reclined position to the upright position when the backrest support structure 542 is displaced between the reclined and upright positions. In the given example, the deflection mounts 614 exert a pressure about the second pivot point 518 of approximately 73.67 Newton-meters (652 inch-pounds) when the backrest support structure 542 is in the upright position and the moment arm deflection mount 638 is in the low-tension setting, and of approximately 105.41 Newton-meters (933 inch-pounds) when the backrest support structure 542 is in the reclined position and the moment arm deflection mount 638 is in the low-tension setting. The moment arm deflection 638 is in the low tension setting, resulting in a change of approximately 43%. Similarly, the deflection assemblies 614 exert a torque about the second pivot point 518 of approximately 166.09 Newton-meters (1.47E+03 inch-pounds) when the backrest support structure 542 is in the upright position and the moment arm deflection assembly 638 is in the high tension setting, and approximately 291.50 Newton-meters (2.58E+03 inch-pounds) when the backrest support structure 542 is in the reclined position and the moment arm deflection assembly 638 is in the high tension setting, resulting in a change of approximately 75%.This significant change in the amount of torque exerted by the deflection mounts 614 between the low tension setting and the high tension setting of the moment arm deflection mount 638 when the backrest support structure 542 is displaced between the upright and reclined positions, allows the total chair assembly 10 to provide appropriate backrest support to users of varying height and weight. The auxiliary adjustment assembly 648 (Figures 53 and 54) assists an operator in moving the moment arm deflection assembly 638 from the high-tension adjustment to the low-tension adjustment. The auxiliary adjustment assembly 648 includes a coil spring 738 secured to the front wall 504 of the base structure 504 by means of a mounting structure 740, and a capture member 742 that extends around the shaft 632 secured with link arms 664, and which includes a capture portion 744 that defines an opening 746 that captures the free end 748 of the coil spring 738.The helical spring 738 exerts a force F on the capture member 742 and shaft 632 in an upward vertical direction, and on the shaft 632 that is attached to the link arms or link 664, thereby reducing the amount of input force the user must exert on the control input assembly 500 to move the moment arm deflection assembly 638 from the low tension setting to the high tension setting. As noted above, the seat assembly 16 (Figure 3) is longitudinally deflectable or displaceable with respect to the control assembly 14 between a retracted position C and an extended position D. As further illustrated in Figures 60 and 61, the direct drive assembly 1562 includes a drive assembly 1564 and a joining assembly 1566 that couples the control input assembly 500 with the drive assembly 1564, thereby enabling a user to adjust the linear position of the seat assembly 16 with respect to the control assembly 14. In the illustrated example, the seat support plate 32 (Figure 42) includes C-shaped guide rails 38 which rest around and slide-engage with corresponding guide flanges 1570 of a control plate 1572 of the control assembly 14.A pair of longitudinally extending C-shaped connecting rails 1574 are positioned within corresponding guide rails 38 and engage with the seat support plate 32. A pair of C-shaped bushing members 1576 extend longitudinally within the connecting rails 1574 and are positioned between the connecting rails 1574 and the guide flanges 1570. The drive assembly 1564 includes a rack member 1578 having a plurality of downwardly extending teeth 1580. The drive assembly 1564 further includes a rack guide 1582 having a C-shaped cross-sectional configuration that defines a channel 1584 that slides into the rack member 1578. The rack guide 1582 includes a relief 1586 located along its entire length which receives by coupling a bearing member 1588 therein, where the. The bearing member 1588, as illustrated in dashed lines, shows the mounting alignment between the bearing member 1588 and the relief 1586 of the guide rail 1582, and wherein, furthermore, the bearing member, as illustrated in solid lines, shows the mounting alignment between the bearing members 1588 and the rack member 1578. Alternatively, the bearing member 1588 can be formed as an integral portion of the rack guide 1582. The drive assembly 1564 further includes a drive shaft 1590 having a first end 1592 universally coupled with the control input assembly 500 and a second end 1594 having a plurality of radially spaced teeth 1596.In the assembly, the seat support plate 32 is slidably coupled with the control plate 1572 as described above, with the rack member 1578 being secured to a lower side of the seat support plate 32 and the rack 1582 being secured within an upwardly opening channel 1598 of the control plate 1572. In operation, an input force exerted by the user on the control input assembly 500 is transferred to the drive assembly 1564 via the joining assembly 1566, thereby driving the teeth 1596 of the drive shaft 1590 against the teeth 1580 of the rack member 1578 and causing the rack member 1578 and the seat support plate 32 to slide relative to the guide rail 1582 and the control plate 1572. With further reference to Figures 62-64, the chair assembly 10 includes a 1600 height adjustment assembly that allows vertical adjustment of the seat 16 and backrest 18 relative to the base assembly 12. The 1600 height adjustment assembly includes the pneumatic cylinder 28, which is located vertically in the center column 26 of the base assembly 12 in a known manner. A clamping structure 1602 is secured to the housing or base structure 502, and an upper end portion 1604 of the pneumatic cylinder 28 is received in an opening 1606 (Figure 64) of the base structure 502 in a known manner. The pneumatic cylinder 28 includes an adjusting valve 1608 that can be diverted downward relative to the pneumatic cylinder 28 to provide height adjustment. A bell crank 1610 has an upwardly extending arm 1630 and a horizontally extending arm 1640 configured to engage the release or relief valve 1608 of the pneumatic cylinder 28. The bell crank 1610 is rotatably mounted to the clamp 1602. A cable assembly 1612 is operatively connected to the bell crank 1610 by an adjusting wheel / lever 1620. The cable assembly 1612 includes an inner cable 1614 and an outer cable or sheath 1616.The outer lining 1616 includes a spherical fitting 1618 that is rotatably received in a spherical receptacle 1622 formed in the clamp 1602. A second spherical fitting 1624 connects to an end 1626 of the inner cable 1614. A second spherical fitting 1624 is rotatably received in a second spherical receptacle 1628 of the upwardly extending arm 1630 of the bell crank 1610 to allow rotational movement of the cable end during height adjustment. A second outer end portion 1632 of the inner cable 1614 is wound around the wheel 1620, and an end fitting 1634 is connected to the inner cable 1614. A tension spring 1636 is connected to the end fitting 1634 and to the seat structure at point 1638. The spring 1636 exerts tension on the inner cable 1614 in the same direction that the cable 1614 is deflected or displaced to rotate the bell crank 1610 when the valve 1608 is released. Although the spring 1636 does not generate sufficient force to actuate the valve 1608, it does generate sufficient force to deflect the arm. RRQQnn / LZnZ / E / Yli 1640 of the bell handle 1610 makes contact with the valve 1608. In this way, any loss of movement or losses that might otherwise exist due to component tolerances are eliminated. During operation, a user manually rotates the adjusting wheel 1620, thereby generating tension on the internal cable 1614. This causes the bell handle 1610 to rotate, which in turn causes the arm 1640 of the bell handle 1610 to press against and actuate the valve 1608 of the pneumatic cylinder 28. An internal spring (not shown) of the pneumatic cylinder 28 deflects the valve 1608 upwards, causing the valve 1608 to return to an unactuated position after the adjusting wheel 1620 is released. The control input assembly 500 (Figures 42 and 65-67) comprises a first control input assembly 1700 and a second control input assembly 1702, each adapted to communicate user inputs to chair components and elements attached thereto, and housed within a housing assembly 1704. The control input assembly 500 includes an anti-actuation assembly 1706, an overload clutch assembly 1708, and a button or knob 1710. The backrest anti-actuation mechanism or assembly 1706 prevents the direct drive assembly 1562 (Figures 60 and 61) and the seat assembly 16 from being actuated between the retracted and extended positions, C, D, without control assembly 1700 input.The backup anti-drive assembly 1706 is received within an interior 1712 of the housing assembly 1704 and includes an adapter 1714 that includes a male portion 1716 of a universal adapter coupled to the second end 1594 of the drive shaft 1590 (Figure 61) at one end thereof, and that includes a grooved connector 1717 at the opposite end. A cam member 1718 is coupled to the adapter 1714 via a clutch member 1720. Specifically, a cam member 1718 includes a splined end 1722 coupled for rotation with the button or knob 1710, and a cam end 1724 having an external cam surface 1726. The clutch member 1720 (Figure 66B) includes a pair of inwardly positioned grooves 1723 that slip-engage the splined connector 1717 having a cam surface 1730 that cam-engages the cam surface 1726 of the cam member 1718, as described below.The clutch member 1720 has a conical clutch surface 1719 that is engaged by a locking ring 1732, which is locked to rotation with respect to the housing assembly 1704 and includes a conical clutch surface 1721 that corresponds to the clutch surface 1719 of the clutch member 1720 and cooperates with it to form a conical clutch. A helical spring 1734 deflects the clutch member 1720 into engagement with the locking ring 1732. Without input, the deflection spring 1734 forces the tapered surface of the clutch member 1720 into engagement with the tapered surface of the locking ring 1732, thereby preventing back-actuation or adjustment of the seat assembly 16 between the retracted and extended positions C, D, simply by applying a backward or forward force to the seat assembly 16 without input from the first control assembly 1700. In operation, an operator moves the seat assembly 16 between the retracted and extended positions C, D by actuating the direct-drive assembly 1562 via the first control input assembly 1700. Specifically, the rotational force exerted on the button 1710 by the user is transmitted from the button 1710 to the cam member 1718. As the cam member 1718 rotates, the outer cam surface 1726 of the cam member 1718 acts on the cam surface 1730 of the cam member 1718. RRQQnn / LZnZ / E / Yli of clutch 1720, thereby overcoming the deflection force of the spring 1734 and forcing the clutch member 1720 into an engaged position, where the clutch member 1720 disengages the locking ring 1732. The rotational force is then transmitted from the cam member 1718 to the clutch member 1720, and then to the adapter 1714 which is coupled to the direct drive assembly 1562 via the link or connecting assembly 1566. It should be noted that a slight amount of tolerance within the first control input assembly 1700 allows slight movement (or oscillation) of the cam member 1718 in the linear and rotational directions when the clutch member 1720 is displaced between the engaged and disengaged positions. A rotational annular damping element 1736 comprising thermoplastic elastomer (TPE) is located within the interior 1712 of the housing 1704 and is attached to the clutch member 1720. In the illustrated example, the damping element 1736 is compressed against and frictionally engaged with the inner wall of the housing assembly 1704. The first 1700 entry control assembly also includes a second button or knob 1738 adapted to allow a user to adjust the vertical position of the chair assembly between the lowered position A and the raised position B, as described below. The second control input assembly 1702 is adapted to adjust the tension exerted on the backrest assembly 18 during reclining, and to control the amount of reclining of the backrest assembly 18. A first button 1740 is operatively coupled to the moment deflection arm assembly 638 by the moment deflection link or connecting assembly 646. Specifically, the second control input assembly 1702 includes a male universal coupling portion 1742 that couples with the female universal coupling portion 692 (Figures 53 and 55) of the shaft 676 of the moment deflection link assembly 646. A second button 1760 is adapted to adjust the amount of recline of the backrest assembly 18 via a cable assembly 1762 that operatively couples the second button 1760 to a variable backrest stop assembly 1764 (Figure 67). The cable assembly 1762 includes a first cable routing structure 1766, a second cable routing structure 1768, and a cable tube 1770 extending between them and slidingly receiving an actuating cable 1772 therein. The cable 1772 includes a distal end 1774 that is fixed relative to the base structure 502 and is deflected in a direction 1776 by means of a helical spring 1778.The variable backrest stop assembly 1764 includes a stop member 1780 having a plurality of vertically graduated steps 1782, a support bracket 1784 fixedly supported relative to the seat assembly 16, and a sliding member 1786 slidably coupled to the support bracket 1784 to slide in a fore-and-aft direction 1788, and fixedly coupled to the stop member 1780 via a pair of screws 1790. Cable 1772 is held between the stop member 1780 and the sliding member 1786 such that longitudinal movement of cable 1772 causes the stop member 1780 to move in the fore-and-aft direction 1788. In operation, a user adjusts the amount of backrest recline possible by adjusting the location of the stop member 1780 via an input to the second button. 1760.The amount of available backrest tilt is limited by the selection step 1782 of the stop member 1780 connecting a rear edge 1792 of the base structure 502 when the backrest assembly 18 is moved from the upright position to the. RRQQnn / LZnZ / E / Yli reclining position. Each arm assembly 20 (Figures 68-70) includes an arm support assembly 800 rotatably supported from an arm base structure 802, and adjustablely supports an armrest assembly 804. The arm support assembly 800 includes a first arm member 806, a second arm 808, a support structure 810, and an armrest mounting support member 812 that cooperate to form a 4-rod joining assembly. In the illustrated example, the first arm member 806 has a U-shaped cross-section configuration and includes a first end 814 rotatably coupled to the arm support structure 810 for rotation about a pivot point 816, and a second end 818 rotatably coupled to the armrest mounting support member 812 for pivoting motion about a pivot point 820.The second arm member 808 has a U-shaped cross-section configuration and includes a first end 822 rotatably coupled to the arm support structure 810 to rotate about a pivot point 824, and a second end 826 rotatably coupled to the armrest mounting support member 812 to rotate about a pivot point 828. As illustrated, the 4-rod joining assembly of the arm support assembly 800 allows the armrest assembly 804 to be adjusted to a fully raised position K and a fully lowered position L, where the distance between the fully raised position K and the fully lowered position L is preferably at least approximately 4 inches (10.16 cm).Each arm further includes a first arm cover or cladding member 807 having a U-shaped cross-section configuration and a first edge portion 809, and a second arm cover or cladding member 811 having a U-shaped cross-section configuration and a second edge portion 813, wherein the first arm member 806 is housed within the first arm cover member 807 and the second arm member 808 is housed within the second arm cover member 811, such that the second edge portion 813 and the first edge portion 809 overlap each other. Each arm base structure 802 includes a first end 830 connected to the control assembly 14, and a second end 832 rotatably supporting the arm support structure 810 for rotation of the arm assembly 20 about the vertical axis 835 in direction 837. The first end 830 of the arm base structure 802 includes a body portion 833 and a tapered bayonet portion 834 extending outward therefrom. In the assembly, the body portion 833 and bayonet portion 834 of the first end 830 of the arm base structure 802 are received between the control plate 572 and the seat support structure 282, and are fastened to it by a plurality of mechanical fasteners (not shown) that extend through the body portion 833 and bayonet portion 834 of the arm base structure 802, the control plate 572, and the seat support structure 282.The second end 832 of the base arm structure 802 rotatably receives the arm support structure 810 on it. As best illustrated in Figure 71, the arm base structure 802 includes an upwardly opening bearing receptacle 836 having a cylindrical upper portion 838 and a tapered lower portion 840. A bushing member 842 is located within the bearing receptacle 836 and is configured similarly to the lower portion 840 of the bearing cavity or receptacle 836, including RRQQnn / LZnZ / E / Yli a tapered portion 846. The arm support structure 810 includes a lower end having a cylindrical upper portion 848 and a tapered lower portion 850 received within the lower portion 846 of the bushing member 842. An upper end 852 of the arm support structure 810 is configured to engage operatively within the vertical locking arrangement, as described below. The bolt member 854 is positioned within a centrally located bore 856 extending axially from the arm support structure 810.In the illustrated example, the bolt member 854 is formed of steel, while the upper end 852 of the arm support structure 810 comprises a powdered metal formed around a proximal end of the bolt member 854, and wherein the combination of the upper end 852 and the pivot bolt 854 is encapsulated within an outer aluminum sheath. A distal end 853 of the bolt member 854 includes an axially extending threaded hole 855 that receives a threaded adjustment screw 857. The base structure of the arm 802 includes a second cylindrical receptacle separated from the bearing receptacle 836 by a wall 860.A helical spring 864 is placed around the distal end 853 of the bolt member 854 within the second cavity or receptacle 858, and is captured between the wall 860 of the arm base structure 802 and a washer member 866, so that a helical spring 864 exerts a downward force 868 in the direction of the arrow on the bolt member 854, thereby pulling the lower end of the arm support structure 810 into a friction coupling with the bushing member 842, and the bushing member 842 into a tight friction coupling in the bearing cavity 836 of the arm base structure 802.The adjusting screw 857 can be adjusted to regulate the amount of frictional interference between the arm support structure 810, the bushing member 842, and the arm base structure 802, thereby increasing the force required by the user to move the arm assembly 20 around the pivot cavity 835 in the rotation direction 837. The pivoting connection between the arm support structure 810 and the arm base structure 802 allows the complete arm assembly 800 to pivot inward in direction 876 (Figure 72) from a line 874 extending through the pivot access 835 and parallel to the centerline 872 of the seat assembly 16, and outward from line 874 in direction 878. Preferably, the arm assembly 20 pivots at least 17° in direction 876 from line 874, and at least 22° in direction 878 of line 874. With further reference to Figures 73-75, the vertical height adjustment of the armrest is effected by rotating the 4-rod linkage forming the first arm member 806, the second arm member 808, the support structure 810, and the armrest mounting support member 812. A gear member 882 includes a plurality of teeth 884 arranged in an arc around the pivot point 816. A locking member 886 is rotatably mounted to the arm 806 at a pivot point 888 and includes a plurality of teeth 890 that selectively engage with the teeth 884 of the gear member 882. When the teeth 884 and 890 are engaged, the height of the armrest 804 is fixed due to the rigid triangle formed between the pivot points 816, 824, and 888. If a force is applied F4 downwards to the armrest, a counterclockwise moment is generated (Figure 74) on the locking member 886.This moment pushes teeth 890 into engagement with teeth 884, thereby securely locking the armrest height. An elongated locking member 892 is rotatably mounted to the arm 806 at the pivot point RRQQnn / LZnZ / E / Yli 894. A low-friction polymeric bearing member 896 is positioned over the upper curved portion 893 of the elongated locking member 892. As discussed in further detail later, a manual release lever or member 898 includes a terminal area 900 that can be deflected upward by a user to selectively release the teeth 890 of the locking member 886 from the teeth 884 of the gear member 882 to allow vertical height adjustment of the armrest. A leaf spring 902 includes a first end 904 that engages a groove 906 formed in an upper edge 908 of the elongated locking member 892. The leaf spring 902 is thus raised to the locking member 892 in the groove 906. An upwardly extending tab 912 of the elongated locking member 892 is received in an elongated groove 910 of the leaf spring 902, thereby locating the spring 902 relative to the locking member 892. The upward-facing end 916 of the leaf spring 902 rests (Figure 1) on the button 918 of the locking member 886, thereby generating a moment that tends to rotate the locking member 886 in a clockwise (released) direction (Figure 75) about the pivot point 888.The leaf spring 902 also generates a clockwise moment about the elongated locking member 892 in the slot 906, and also generates a moment about the locking member 886 that tends to rotate the locking member 886 about the pivot point 816 in a clockwise (released) direction. This moment tends to disengage the gears 890 from the gears 884. If the gears 890 are disengaged from the gears 884, the height of the armrest assembly can be adjusted. The locking member 886 includes a cavity or cut 920 (Figure 74) that receives the pointed end 922 of the elongated locking member 892. The cavity 920 includes a first shallow V-shaped portion having a vertex 924. The cavity also includes a small cavity or cleft 926, and a cross-surface, upwardly oriented surface 928 immediately adjacent to the cleft 926. As discussed above, the leaf spring 902 generates a moment acting on the locking member 886 that tends to disengage the gears 890 from the gears 884. However, when the tip or end 922 of the elongated locking member 892 engages with the groove 926 of the cavity 920 of the locking member 886, this engagement prevents rotational movement of the locking member 886 in the clockwise (released) direction, thereby locking the gears 890 and gears 884 in engagement with each other and preventing height adjustment of the armrest. To release the arm assembly for armrest height adjustment, a user pulls upward on the end area 900 against a small leaf spring 899 (Figure 74). The release member 898 rotates about an axis 897 extending in a fore-and-aft direction, and an internal manual release end 895 of the lever 898 pushes downward against the bearing member 896 and the upper curved portion 893 (Figure 75) of the elongated locking member 892. This generates a downward force that causes the elongated locking member 892 to rotate about the pivot point 894. This displaces the end 922 (Figure 74) of the elongated locking member 892 upward so that it is adjacent to the shallow apex 924 of the cavity 920 of the locking member 886.This deflection or displacement of the locking member 892 releases the locking member 886, so that the locking member 886 rotates in a clockwise (released) direction due to the deflection of the leaf spring 902. This rotation causes the gears 890 to disengage from the gears 884 to allow adjustment of the mounting height. RRQQnn / LZnZ / E / Yli armrest The armrest assembly is also configured to prevent disengagement of the height adjustment member while a downward force F4 (Figure 74) is being applied to the armrest end area 804. Specifically, due to the 4-rod link formed by the arm members 806, 808, the arm support structure 810, and the armrest mounting support member 812, the force F4 will tend to cause the pivot point 820 to move toward the pivot point 824. However, the elongated locking member 892 is generally located on a line between the pivot point 820 and the pivot point 824, thus preventing downward rotation of the 4-rod link. As noted earlier, the downward force F4 causes teeth 890 to mesh tightly with teeth 884, securely locking the armrest height.If the release lever 894 is actuated while the downward force F4 is being applied to the armrest, the locking member 892 will move, and the end 922 of the elongated locking member 892 will disengage from the groove 926 of the cavity 920 of the locking member 886. However, the movement of the locking member 886 causes the teeth 898 and 894 to remain engaged even if the locking member 892 is moved to a release position. Thus, the configuration of the 4-rod linkage, the locking members 886, and the engagement member 882 provides a mechanism by which the height adjustment of the armrest cannot be effected if a downward force F4 is acting on the armrest. As best illustrated in Figures 76-78, each armrest assembly 804 is adjustablely supported from an associated arm support assembly 800, so that the armrest assembly 804 can pivot inward and outward about a pivot point 960 between an in-line position M and the rotated positions N. Each armrest support assembly is also linearly adjustable with respect to the associated arm support assembly 800 between a retracted position O and an extended position P. Each armrest assembly 800 includes an armrest housing assembly 962 integrated with the armrest assembly support member 812, which defines a lower space 964. The armrest assembly 804 also includes a support plate 966 having a flat body portion 968, a pair of openings receiving a mechanical fastener 969, and an upwardly extending support projection 970.A rectangular slider housing 972 includes a flat portion 974 having an oval-shaped opening 976 extending through it, a pair of side walls 968 extending longitudinally along and perpendicular to the flat portion 974, and a pair of end walls 981 extending laterally through the ends of and perpendicular to the flat portion 974. The armrest assembly 804 further includes a rotationally and linearly adjusting member 980 having a flat body portion defining an upper surface 984 and a lower surface 986. A center-located opening 988 extends through the body portion 988 and rotatably receives the pivot projection 970 therein.The rotational and linear adjustment member 980 further includes a pair of arched openings 990 located at opposite ends thereof and a pair of laterally separated, arched flange assemblies 991 extending upward from the upper surface 984 and defining a plurality of retainers 993 between them. A rotational selection member 994 includes a flat body portion 996 and a pair of flexible, springy fingers 998 located at the center thereof, each including a downwardly extending coupling portion 1000. RRQQnn / LZnZ / E / Yli Each armrest assembly 804 further includes an arm pad substrate or end area 1002 and an arm pad member 104 overmolded onto the substrate 1002. In the assembly, the support plate 966 is placed on top of the armrest housing assembly 962, the slide housing 972 on top of the support plate 966, so that a lower surface 1006 of the flat portion 974 is friction-fitted or engaged to an upper surface 1008 of the support plate 966, the rotational and linear adjustment member 980 between the side walls 978 and the end walls 980 of the slide housing 972, so that the lower surface 986 of the rotational and linear adjustment member is friction-fitted to the flat portion 974 of the slide housing 972, and the rotational selection member 974 is located on top of the rotational and linear adjustment member 980.A pair of mechanical fasteners, such as rivets 1010, extend through the openings 999 of the rotational selection member 994, the arched openings 990 of the rotational and linear adjustment member 980, and the openings 968 of the support plate 966, and are threaded onto the armrest housing assembly 972, thereby securing the support plate 966, the rotational and linear adjustment member 980, and the rotational selection member 994 against linear movement relative to the armrest housing 962. The substrate 1002 and the arm pad member 102 are then secured to the slider housing 972. The arrangement described above allows the slider housing 972, the substrate 1002, and the arm pad member 1004 to slide in a linear direction so that the armrest assembly 804 can be adjusted between the retracted position O and the extended position P.The rivets 1010 can be adjusted to regulate the clamping force exerted on the slide rail 972 by the support plate 966 and the rotational and linear adjustment member 980. The substrate 1002 includes an upwardly extending, center-located portion 1020 and a corresponding downwardly positioned cavity having a pair of longitudinally extending side walls (not shown). Each side wall includes a plurality of flanges and retainers similar to the flanges 991 and retainers 993 previously described. In operation, the pivot projection 970 engages with the cavity retainers when the arm pad 1004 is displaced in the linear direction, thereby providing haptic feedback to the user.In the illustrated example, pivot projection 972 includes a groove 1022 that allows the end of pivot projection 970 to deform elastically when pivot projection 970 engages with the retainers, thereby reducing wear on the latter. The arched openings 990 of the rotational and linear adjustment member 980 allow the adjustment member 980 to rotate about the pivot projection 970 of the support plate 966, and the armrest assembly 804 to be adjusted between the in-line position M and the angled position N. In operation, the coupling portion 100 of each finger 998 of the rotational selection member selectively engages the detents 992 defined between the flanges 991, thereby allowing the user to place an armrest assembly 804 in the selected rotational position and providing haptic feedback to the user when the armrest assembly 804 is rotationally adjusted. One chair mounting configuration is illustrated in a variety of views, including a perspective view (Figure 79), a front elevation view (Figure 80), a first side elevation view (Figure 81), a second side elevation view (Figure 82), a rear elevation view (Figure 83), a top plan view (Figure 84), and a bottom plan view (Figure 85). RRQQnn / LZnZ / E / Yll Another configuration of armless chair 20 is illustrated in a variety of views, including a perspective view (Figure 86), a front elevation view (Figure 87), a first side elevation view (Figure 88), a second side elevation view (Figure 89), a rear elevation view (Figure 90), a top plan view (Figure 91), and a bottom plan view (Figure 92). The configurations of the five chair assemblies illustrated in Figures 79–92 may include all, some, or none of the features described here. In the preceding description, it is considered appreciated by those skilled in the art that alternative combinations of the different components and elements of the invention and modifications to the invention can be made without departing from the described concept, such as applying the inventive concepts as described herein to vehicle seats, stadium seats, home chairs, theater seats, and the like. Some modifications should be considered as included in the following claims, unless those claims expressly state otherwise. RRQQnn / LZnZ / E / Yli

Claims

1. A control assembly for a chair, characterized in that it comprises: a base structure; a seat support structure coupled to the base structure, wherein the seat support structure is adapted to support a user seated thereon; a backrest support structure movably coupled to the base structure, wherein the backrest support structure moves between an upright position and a reclined position; and at least one deflection assembly that exerts a deflection torsion that deflects the backrest support structure from the reclined position to the upright position, wherein the deflection torsion is adjustable between first and second magnitudes, and wherein the second magnitude is more than twice the first magnitude when the backrest support structure is in at least one of the upright and reclined positions.

2. The control assembly according to claim 1, further characterized in that: the second magnitude of the deflection torsion is more than twice the first magnitude of the deflection torsion when the backrest support structure is in the upright position and when the backrest support structure is in the reclined position.

3. The control assembly according to claim 1, further characterized in that: the magnitude of the deflection torsion increases from a vertical torsion when the backrest support structure is in the vertical position to a reclined torsion when the backrest support structure is in the reclined position.

4. The control assembly according to claim 3, further characterized in that: the reclining torsion is less than twice the vertical torsion when the deflection torsion is adjusted to the former magnitude.

5. The control assembly according to claim 3, further characterized in that: the reclining torsion is approximately 43% greater than the vertical torsion when the deflection torsion is adjusted to the former magnitude.

6. The control assembly according to claim 3, further characterized in that: the reclining torsion is less than twice the vertical torsion when the deflection torsion is adjusted to the second magnitude.

7. The control assembly according to claim 6, further characterized in that: the reclining torsion is approximately 75% greater than the vertical torsion when the deflection torsion is adjusted to the second magnitude.

8. The control assembly according to claim 1, further characterized in that it additionally comprises: an adjustment assembly operatively coupled to at least one deflection assembly for adjusting the deflection torque between the first and second magnitudes, wherein the adjustment assembly adjusts the at least one deflection assembly between a first configuration corresponding to the first magnitude of the deflection force and a second configuration corresponding to the second magnitude of the deflection force. RRQQnn / LZnZ / E / Yli 9. The control assembly according to claim 8, further characterized in that: the adjustment assembly includes a movable input member that changes the magnitude of the deflection torque after the movement of the movable input member between a first position and a second position.

10. The control assembly according to claim 9, further characterized in that: the deflection torsion is generated by a spring member having a first end, a second end and a defined length between the first end and the second end, and wherein a change in the length of the spring member changes the magnitude of the deflection torsion between the first and second magnitudes.

11. The control assembly according to claim 1, further characterized in that: the seat support structure is rotatably coupled to the base structure and rotates between the upright and reclined positions.

12. A control assembly for a chair, characterized in that it comprises: a base structure including a support structure that is attached to the floor; a seat support structure coupled to the base structure, wherein the seat support structure is adapted to support a user seated thereon; a backrest support structure movably coupled to the base structure, for movement between an upright position and a reclined position;and at least one deflection assembly that exerts a deflection torsion that deflects the backrest support structure from the reclined position to the upright position, wherein the deflection torsion is adjustable between first and second magnitudes, and wherein the second magnitude is greater than the first magnitude, and wherein, when the deflection torsion is set to the first magnitude, the deflection torsion increases from a first vertical torsion when the backrest support structure is in the upright position to a first reclined torsion when the backrest support structure is in the reclined position, and wherein the first reclined torsion is less than twice the first vertical torsion.

13. The control assembly according to claim 12, further characterized in that: the first reclined twist is approximately 43% greater than the first vertical twist.

14. The control assembly according to claim 13, further characterized in that: when the deflection torque is set to the second magnitude, the deflection torque increases from a second vertical torsion when the backrest support structure is in a vertical position to a second reclined torsion when the backrest support structure is in the reclined position, and wherein the second reclined torsion is less than twice the second vertical torsion.

15. The control assembly according to claim 14, further characterized in that: the second reclined twist is approximately 75% greater than the second vertical twist.

16. The control assembly according to claim 14, further characterized in that: when the deflection torque is set to the first magnitude, the deflection torque increases linearly from the first vertical torque to the first reclined torque to define a first tilt; and wherein, when the deflection torque is set to the second magnitude, the deflection torque increases linearly from the second vertical torque to the second reclined torque to define a second tilt; and wherein the second tilt is more than twice the first tilt. RRQQnn / LZnZ / E / Yli 17. The control assembly according to claim 16, further characterized in that: the second inclination is approximately four times the first inclination.

18. The control assembly according to claim 12, further characterized in that it additionally comprises: 5 an adjustment assembly operatively coupled to the at least one deflection assembly for adjusting the deflection torque between the first and second magnitudes, wherein the adjustment assembly adjusts the at least one deflection assembly between a first configuration corresponding to the first magnitude of the deflection force and a second configuration corresponding to the second magnitude of the deflection force. 10 19. The control assembly according to claim 18, further characterized in that: the deflection torque is generated by a spring member having a first end, a second end, and a defined length between the first end and the second end, and wherein a change in the length of the spring member changes the magnitude of the deflection torque between the first and second magnitudes. 15 20.The control assembly according to claim 12, further characterized in that: the seat support structure is rotatably coupled to the base structure and rotates between the upright and reclined positions. RRQQnn / LZnZ / E / Yli.

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