Title:
Tilt chair and methods for the use thereof
Document Type and Number:
Kind Code:
A1

Abstract:
A tiltable chair including a base, a fulcrum member having a curved support surface, a back support pivotally connected to the base at a pivot axis and pivotable between at least an upright position and a rearward tilt position, and at least one leaf spring having first and second ends, with the first end being restrained by the base. The at least one leaf spring engages the curved support surface of the fulcrum member at a first contact point when the back support is in the upright position and at a second contact point when the back support is in the rearward tilt position, wherein the second contact point is positioned rearwardly on the at least one leaf spring relative to the first contact point. A link member is pivotally connected to the back support at a first pivot location and is pivotally connected to the at least one leaf spring at a second pivot location. The link member defines a vector between the first and second pivot locations and the first pivot location and the pivot axis define a plane. The vector and the plane define a first angle when the back support is in the upright position and a second angle when the back support is in the rearward tilt position, wherein the second angle is closer to ninety degrees than the first angle. A method of using a chair is also provided.

Representative Image:
Tilt chair and methods for the use thereof
Inventors:
Schmitz, Johann Burkhard (Berlin, DE)
Plikat, Claudia (Berlin, DE)
Neubert, Nicolai (Berlin, DE)
Zwick, Carola E. M. (Berlin, DE)
Zwick, Roland R. O. (Berlin, DE)
Aldrich, John F. (Grandville, MI, US)
Hill, Christopher C. (Holland, MI, US)
Slagh, James D. (Holland, MI, US)
Vanderiet, Douglas M. (Holland, MI, US)
      Plaque It!

Application Number:
10/738641
Publication Date:
09/23/2004
Filing Date:
12/17/2003
View Patent Images:
Images are available in PDF form when logged in. To view PDFs, Login  or  Create Account (Free!)
Export Citation:
Click for automatic bibliography generation
Primary Class:
297/300.100
Other Classes:
297/301.100, 297/303.100
International Classes:
(IPC1-7): A47C001/024
Attorney, Agent or Firm:
BRINKS HOFER GILSON & LIONE,Andrew D. Stover (P.O. BOX 10395, CHICAGO, IL, 60610, US)
Claims:

What is claimed is:



1. A chair comprising: a housing; a fulcrum member having a curved support surface; a back support pivotally connected to said housing at a pivot axis, said back support pivotable between at least an upright position and a rearward tilt position; at least one leaf spring having first and second ends, said first end restrained by said housing, wherein said at least one leaf spring engages said curved support surface of said fulcrum member at a first contact location when said back support is in said upright position and wherein said at least one leaf spring engages said curved support surface of said fulcrum at a second contact location when said back support is in said rearward tilt position, and wherein said second contact location is positioned rearwardly on said at least one leaf spring relative to said first contact location; and a link member pivotally connected to said back support at a first pivot location and pivotally connected to said at least one leaf spring at a second pivot location, wherein said link member defines a vector between said first and second pivot locations, wherein said first pivot location and said pivot axis define a plane, wherein said vector and said plane define a first angle when said back support is in said upright position, wherein said vector and said plane define a second angle when said back support is in said rearward tilt position, and wherein said second angle is closer to ninety degrees than said first angle.

2. The chair of claim 1 wherein said fulcrum member is moveably supported by said housing and is moveable relative to said spring between said first and second ends thereof.

3. The chair of claim 1 wherein said first pivot location is positioned forwardly of said second pivot location.

4. The chair of claim 3 wherein said contact locations are positioned forwardly of said pivot axis.

5. The chair of claim 1 wherein said pivot axis is positioned forwardly of said first pivot location.

6. The chair of claim 1 wherein at least a portion of said curved support has a radius of between about 0.50 inches and about 1.50 inches.

7. A method of using a chair comprising: providing a body support member comprising a support member coupled to a housing about a pivot axis, and an adjustable biasing member biasing said body support member about said pivot axis; supporting a user with said body support member, wherein said user has a weight of between about 105 and 300 pounds; pivoting said body support member 20 degrees about said pivot axis from a first position to a second position; applying an applied torque to said support member with said user about said pivot axis; and adjusting said biasing member and applying a restoring torque to said support member opposite said applied torque with said biasing member about said pivot axis such that said restoring torque is within about 20% of said applied torque as said body support member is pivoted about said pivot axis between said first and said second positions.

8. The method of claim 7 wherein said restoring torque is within about 15% of said applied torque as said body support member is pivoted about said pivot axis between said first and said second positions.

9. The method of claim 7 wherein said user is a first user having a weight of about 105 pounds, said applied torque is a first applied torque and said restoring torque is a first restoring torque, and further comprising removing said first user from said body support member and supporting a second user with said body support member, wherein said user has a weight of about 300 pounds; pivoting said body support member 20 degrees about said pivot axis from said first position to said second position while supporting said second user; applying a second applied torque to said support member with said second user about said pivot axis; and adjusting said biasing member and applying a second restoring torque to said support member opposite said second applied torque with said biasing member about said pivot axis such that said second restoring torque is within about 20% of said second applied torque as said body support member is pivoted about said pivot axis between said first and said second positions while supporting said second user.

10. The method of claim 9 wherein said second restoring torque is within about 15% of said second applied torque as said body support member is pivoted about said pivot axis between said first and said second positions while supporting said second user.

11. The method of claim 7 wherein said biasing member comprises at least one leaf spring.

12. The method of claim 11 further comprising providing a fulcrum member having a curved support surface, wherein said body support member is pivotally connected to said housing at said pivot axis, and wherein said at least one leaf spring has first and second ends, said first end restrained by said housing and said second end coupled to said body support member, wherein said at least one leaf spring engages said curved support surface of said fulcrum member at a contact location between said first and second ends, and further comprising moving said contact location rearwardly as said body support member is pivoted between said first and second positions.

13. The method of claim 12 further comprising providing a link member pivotally connected to said body support member at a first pivot location and pivotally connected to said at least one leaf spring at a second pivot location, wherein said link member defines a vector between said first and second pivot locations, wherein said first pivot location and said pivot axis define a plane, wherein said vector and said plane define a first angle when said body support member is in said first position, wherein said vector and said plane define a second angle when said body support member is in said second position, and wherein said second angle is closer to ninety degrees than said first angle.

14. The method of claim 12 wherein said fulcrum member is moveably supported by said housing and is moveable relative to said at least one leaf spring between said first and second ends thereof, and wherein said adjusting said biasing member comprises moving said fulcrum member.

15. The method of claim 7 wherein said body support member comprises a backrest.

16. The method of claim 15 wherein said body support member further comprises a seat coupled to said backrest.

17. A method of using a chair comprising: providing a body support member and an adjustable biasing member biasing said body support member; supporting a user with said body support member, wherein said user has a weight of between about 105 and 300 pounds; tilting said body support member about 20 degrees from a first position to a second position; applying an applied force to said support member with said user at a first location on said support member; and adjusting said biasing member and applying a restoring force to said support member opposite said applied force at said first location with said biasing member such that said restoring force is within about 20% of said applied force as said body support member is tilted between said first and second positions.

18. The method of claim 17 wherein said restoring force is within about 15% of said applied force as said body support member is tilted between said first and said second positions.

19. The method of claim 17 wherein said user is a first user having a weight of about 105 pounds, said applied force is a first applied force and said restoring force is a first restoring force, and further comprising removing said first user from said body support member and supporting a second user with said body support member, wherein said user has a weight of about 300 pounds; tilting said body support member 20 degrees from said first position to said second position while supporting said second user; applying a second applied force to said support member with said second user at said first location; and adjusting said biasing member and applying a second restoring force to said support member opposite said second applied force with said biasing member at said first location such that said second restoring force is within about 20% of said second applied force as said body support member is tilted between said first and said second positions while supporting said second user.

20. The method of claim 19 wherein said second restoring force is within about 15% of said second applied force as said body support member is tilted between said first and said second positions while supporting said second user.

21. The method of claim 17 wherein said biasing member comprises at least one leaf spring.

22. The method of claim 21 further comprising providing a fulcrum member having a curved support surface, and wherein said at least one leaf spring has first and second ends, said first end restrained by a housing and said second end coupled to said body support member, wherein said at least one leaf spring engages said curved support surface of said fulcrum member at a contact location between said first and second ends, and further comprising moving said contact location rearwardly as said body support member is tilted between said first and second positions.

23. The method of claim 22 further comprising providing a link member pivotally connected to said body support member at a first pivot location and pivotally connected to said at least one leaf spring at a second pivot location, wherein said link member defines a vector between said first and second pivot locations, wherein said first pivot location and said pivot axis define a plane, wherein said vector and said plane define a first angle when said body support member is in said first position, wherein said vector and said plane define a second angle when said body support member is in said second position, and wherein said second angle is closer to ninety degrees than said first angle.

24. The method of claim 22 wherein said fulcrum member is moveably supported by said housing and is moveable relative to said at least one leaf spring between said first and second ends thereof, and wherein said adjusting said biasing member comprises moving said fulcrum member.

25. The method of claim 17 wherein said body support member comprises a backrest.

26. The method of claim 25 wherein said body support member further comprises a seat coupled to said backrest.

27. A chair comprising: a housing comprising a track having a curvilinear support surface formed within a vertical plane; a back support pivotally connected to said housing about a first horizontal axis; and a seat support pivotally connected to said back support about a second horizontal axis and moveably supported on said support surface of said track.

28. The chair of claim 27 wherein said seat support comprises a rotatable wheel, wherein said wheel engages said track.

29. The chair of claim 28 wherein said housing comprises a pair of said curvilinear tracks, and wherein said seat support comprises a pair of wheels engaging said tracks respectively.

30. The chair of claim 27 wherein at least a portion of said support surface of said track has a convex curvature.

31. A chair comprising: a housing; a seat support supported by said housing; at least one leaf spring comprising a first end supported by said housing and a second end biasing said seat support in an upward direction, wherein said at least one leaf spring flexes within a substantially vertical first plane; and a fulcrum member moveably supported by said housing and having a support surface engaging said at least one leaf spring between said first and second ends, wherein said support surface is not symmetrical about any laterally extending second vertical plane oriented substantially perpendicular to said first plane.

32. The chair of claim 31 further comprising a back support pivotally connected to said seat support at a first pivot axis, wherein said at least one leaf spring biases said seat support and said back support in said upward direction.

33. The chair of claim 32 further comprising a spring link connecting said at least one spring and said back support.

34. A chair comprising: a housing; a back support pivotally connected to said housing about a first horizontal axis; a seat support pivotally connected to said back support about a second horizontal axis; at least one leaf spring comprising a first end supported by said housing and a second end biasing said back support and said seat support in an upward direction; and a fulcrum member moveably supported by said housing and having a curvilinear support surface engaging said at least one leaf spring between said first and second ends, wherein said at least one leaf spring has an initial point of contact with said support surface and wherein a tangent of any point along said support surface slopes rearwardly and downwardly from said initial point of contact.

35. The chair of claim 34 wherein at least a portion of said support surface forms an arc.

36. The chair of claim 35 wherein said arc has a radius of between about 0.50 and 7 inches.

Description:

[0001] This application is a continuation-in-part of U.S. application Ser. No. 10/365,682, filed Feb. 12, 2003, which claims the benefit of U.S. Provisional Application No. 60/418,578, filed Oct. 15, 2002 and U.S. Provisional Application No. 60/356,478, filed Feb. 13, 2002, the entire disclosures of which are hereby incorporated herein by reference.

BACKGROUND

[0002] The present invention relates generally to tiltable chairs, and in particular, to a tilt chair having a flexible back, adjustable armrests, and an adjustable seat depth, and methods for using and/or adjusting the chair, including one or more of the seat, backrest and armrests.

[0003] Chairs of the type typically used in offices and the like are usually configured to allow tilting of the seat and backrest as a unit, or to permit tilting of the backrest relative to the seat. In chairs having a backrest pivotally attached to a seat in a conventional manner, the movement of the backrest relative to the seat can create shear forces which act on the legs and back of the user, and which can also create an uncomfortable pulling of the user's shirt, commonly called “shirt-pull.”

[0004] To enhance the user's comfort and to promote ergonomically healthy seating, synchro-tilt chairs provide for the seat and backrest to tilt simultaneously, but at different rates, preferably with the back tilting at a greater rate than the seat. In general, synchro-tilt chairs are usually configured as a four-bar linkage or as a three-bar, slide linkage. In a three-bar, slide configuration, the sliding path is typically linear. Such chairs often have a multiplicity of components and parts that can be difficult and time consuming to assemble and which require multiple fasteners or joints to connect the components.

[0005] In addition, synchro-tilt chairs normally employ compression and/or tension springs, torsion springs and/or torsion bars, or leaf springs to bias the seat and back upwardly and to counterbalance the rearward tilting of the user. Chairs using these types of springs can have various limitations associated with the type of spring used therein as explained in U.S. Pat. No. 6,250,715, entitled Chair, and assigned to Herman Miller, Inc., the entire disclosure of which is hereby incorporated herein by reference. In addition, the mechanisms used to adjust the load on the spring(s), or the load capability of the spring(s), typically are complicated, and/or require multiple, excessive rotations of a knob or other grippable member to obtain the desired setting.

[0006] Often, such tilt chairs do not provide a balanced ride throughout the range of tilting motion of the chair. Specifically, the restoring force or torque of the chair, and in particular the spring, does not match the force or torque applied by the user throughout the tilting range. Although the applied force and restoring force may balance out at a particular tilt position, such balance does not typically occur throughout the tilting range. Moreover, such balance typically cannot be achieved for a variety of users having different weights and body sizes. As such, the user must exert energy and/or apply an external force to maintain the chair in a particular location.

[0007] It is also desirable to provide a chair that can be adjusted to accommodate the various needs and sizes of the user. For example, it is often desirable to provide a chair having adjustable armrests and an adjustable seat depth. For example, armrests can be provided with vertical adjustment capabilities, lateral adjustment capabilities and pivotable adjustment capabilities about a vertical axis. Often, however, armrests fail to provide such capabilities in combination, and/or employ complex, moving parts and assemblies that can be expensive to manufacture and assemble and difficult to use. Moreover, armrests having vertical adjustment capabilities often employ a support member that extends vertically down along the side of the chair, where the armrest or support member can interfere with the user's legs and other objects as the user moves about in the chair. In addition, the range of adjustment is typically limited to the length of the support member. However, the longer the support member, or the further it extends below the seating surface, the more likely it is to increase the foot print of the chair and interfere with the mobility of the chair.

[0008] Chairs with adjustable seat depths often employ devices and mechanisms to shift the entire seat in a forward and rearward direction relative to the backrest. Therefore, such chairs must provide for structure to allow the seat to move relative to the backrest while at the same time bearing the load of the seat and user. Moreover, such chairs typically must employ an extra support member which allows the seat to move thereon, for example, when the seat or support member are integrated into the linkage assembly.

[0009] Typically, backrests having a resilient and/or flexible material, whether a fabric, elastic membrane or plastic mat, are often supported by a peripheral frame, which surrounds the material. Such construction, however, does not ordinarily permit flexing of the material at the periphery of the backrest, or allow for torsional movement of the backrest. In addition, even in those chairs that employ a resilient material, the material often has uniform mechanical and physical properties across the entire portion of the material.

[0010] Finally, as disclosed for example in U.S. Pat. No. 5,873,634 to Heidmann et al., it is known to connect different seating arrangements to a control housing. However, Heidmann discloses connecting different seating arrangements to a tilt control housing and back support at common connection points. Accordingly, the overall kinematics of the chair cannot be altered or varied, but rather are predetermined by the common connection points. In such a device, only localized adjustments within each seating arrangement can be varied between the different seating arrangements.

SUMMARY

[0011] The present inventions are defined by the claims, and nothing in this section should be read as a limitation on those claims. Rather, by way of general introduction and briefly stated, various preferred embodiments are described that relate to a tiltable chair having a flexible back, adjustable armrests, an adjustable seat depth, various control mechanisms and linkage assemblies, and methods for the use of the various preferred aspects.

[0012] For example and without limitation, in one aspect, the preferred embodiments relate to an adjustable armrest, and the method for the use thereof. In one preferred embodiment, an armrest assembly for a seating structure includes a support member comprising an upwardly extending curved spine portion having a first defined curvature and a stem slidably disposed on the support member and comprising a curved portion having a second defined curvature corresponding to and mating with the first curvature of the spine portion. An armrest is preferably supported by the stem. A latch mechanism is moveable between at least an engaged position and a disengaged position, wherein the latch mechanism engages at least one of the stem and the support member to prevent movement therebetween when in the engaged position. The stem is moveable relative to the support member when the latch mechanism is in the disengaged position.

[0013] In another aspect, one preferred embodiment of the armrest assembly includes a support member, a stem slidably disposed on the support member, an armrest supported by the stem, a latch mechanism and an index member. The latch mechanism is moveable between at least an engaged position and a disengaged position. The latch mechanism engages at least one of the stem and the support member to prevent movement therebetween when in the engaged position. The stem is moveable relative to the support member when the latch mechanism is in the disengaged position. The index member selectively engages at least one of the support member and the stem when the latch mechanism is in the disengaged position as the stem is moved relative to the support member.

[0014] In yet another aspect, in one preferred embodiment, an armrest assembly comprises a platform and an armrest support moveably supported on the platform. The armrest support is moveable between at least a first position and a second position. A linear gear is disposed on one of the platform and the armrest support and extends in a substantially horizontal direction. A pinion gear is rotatably mounted on the other of the platform and the armrest support about a substantially vertical rotation axis. The pinion gear meshes with the linear gear as the armrest support is moved relative to the platform between at least the first and second positions.

[0015] In one preferred embodiment, the armrest assembly includes a pair of pinion gears meshing with each other and a pair of linear gears. Also in one preferred embodiment, one of the platform and the armrest support includes a guide member that moves in a track formed in the other thereof as the armrest support is moved relative to the platform. In one preferred embodiment, first and second guide members move in first and second tracks.

[0016] Various methods of using the various preferred embodiments of the armrest assemblies are also provided.

[0017] In another aspect, one preferred embodiment of a seating structure includes a primary seat support having a rear portion and a front portion and an auxiliary seat support having a rear portion and a front portion. The rear portion of the auxiliary seat support is connected to the front portion of the primary seat support. At least a portion of the auxiliary seat support is flexible, wherein the front portion of the auxiliary seat support is moveable between at least a first and second position relative to the rear portion of the auxiliary seat support as the flexible portion of the auxiliary seat support is flexed.

[0018] In one preferred embodiment, the seating structure includes a linkage assembly connecting the front portion of the auxiliary seat support and one of a housing, which supports the primary seat support, and the primary seat support. In one preferred embodiment, the linkage assembly includes first and second links.

[0019] In one preferred embodiment, the seating structure further includes a lock device releasably connected between the auxiliary seat support and one of the housing and primary seat support.

[0020] In one preferred embodiment, the seating structure comprises a seat support comprising a forward portion, a rear portion and opposite, laterally spaced sides. At least the forward portion is bendable about a substantially horizontal and laterally extending axis between at least a first and second position, wherein the forward portion has a greater curvature when in the second position compared with the first position. A lock device is moveable between at least an engaged position and a disengaged position, wherein the lock device maintains the seat support in at least one of the first and second positions when in the engaged position, and wherein the seat support is bendable between at least the first and second positions when the lock device is in the disengaged position.

[0021] Various methods for adjusting the depth of the seat, or the curvature of the front portion thereof, are also provided.

[0022] In another aspect, one preferred embodiment of a backrest for a seat structure comprises a frame member and a compliant, resilient back member having a top, a bottom and opposite sides. The back member is mounted to the frame member. The back member includes a lumbar region, a thoracic region disposed above the lumbar region, and a lower region disposed below the lumbar region. The lumbar region comprises a first array of openings formed therethrough, with the first array comprising a first plurality of staggered, elongated openings that are elongated in a direction from the top to the bottom of the back member. The thoracic region comprises a second array of openings formed therethrough, with the second array comprising a second plurality of staggered, elongated openings, which are elongated in a direction from the top to the bottom of the back member. The first plurality of openings has a greater elongation on average than the second plurality of openings.

[0023] In another preferred embodiment, a backrest for a seat structure includes a frame member comprising an upper support member and a lower support member spaced from the upper support member, with the upper support member having opposite shoulder portions. A fabric member having a front, body-supporting surface and a rear surface comprises at least one pocket that is received on the opposite shoulder portions. The fabric member is connected to the lower support member and extends in tension between the upper and lower support members. The fabric member comprises a central thoracic region that is free of contact on the rear surface thereof.

[0024] In another aspect, one preferred embodiment of a tiltable chair includes a base, a fulcrum member having a curved support surface, a back support pivotally connected to the base at a pivot axis and pivotable between at least an upright position and a rearward tilt position, and at least one leaf spring having first and second ends, with the first end being restrained by the base. The at least one leaf spring engages the curved support surface of the fulcrum member at a first contact point when the back support is in the upright position and at a second contact point when the back support is in the rearward tilt position, wherein the second contact point is positioned rearwardly on the at least one leaf spring relative to the first contact point. A link member is pivotally connected to the back support at a first pivot location and is pivotally connected to the at least one leaf spring at a second pivot location. The link member defines a vector between the first and second pivot locations and the first pivot location and the pivot axis define a plane. The vector and the plane define a first angle when the back support is in the upright position and a second angle when the back support is in the rearward tilt position, wherein the second angle is closer to ninety degrees than the first angle.

[0025] In yet another aspect, a method of using a chair includes providing a body support member having a support member coupled to a base about a pivot axis and an adjustable biasing member biasing the body support member about the pivot axis. The method further includes supporting a user with the body support member, wherein the user has a weight of between about 105 and 300 pounds, pivoting the body support member 20 degrees about the pivot axis from a first position to a second position, and applying an applied torque to the support member with the user about the pivot axis. The method further includes adjusting the biasing member and applying a restoring torque to the support member opposite the applied torque with the biasing member about the pivot axis such that the restoring torque is within about 20%, and more preferably without about 15%, of the applied torque as the body support member is pivoted about the pivot axis between the first and second positions.

[0026] In another aspect, one preferred embodiment of a chair comprises a housing comprising a track having a curvilinear support surface formed within a vertical plane. A back support is pivotally connected to the housing about a first horizontal axis, and a seat support is pivotally connected to the back support about a second horizontal axis and is moveably supported on the support surface of the track.

[0027] In yet another aspect, the chair comprises a housing, a seat support supported by the housing, and at least one leaf spring comprising a first end supported by the housing and a second end biasing the seat support in an upward direction, wherein the at least one leaf spring flexes within a substantially vertical first plane. A fulcrum member is moveably supported by the housing and has a support surface engaging the at least one leaf spring between the first and second ends. The support surface is preferably not symmetrical about any laterally extending second vertical plane oriented substantially perpendicular to the first plane.

[0028] In yet another aspect, one preferred embodiment of a chair includes a fulcrum member having a curvilinear support surface engaging at least one leaf spring between a first and second end. Preferably, a tangent of any point along the support surface of the fulcrum slopes rearwardly and downwardly.

[0029] In yet another aspect, one preferred embodiment of a seating structure includes a linkage assembly comprising a first and second link pivotally connected to a housing about a first pivot axis. The first link is pivotally and slidably connected to a fulcrum at a second pivot axis spaced from the first pivot axis and the second link is pivotally and slidably connected to the fulcrum at a third pivot axis spaced from the first and second pivot axes. In one preferred embodiment, an actuator member pivotally engages the first and second links at pivot axes spaced from the first, second and third pivot axes. In various preferred embodiments, various tracks are formed in one of the links and the fulcrum member, the actuator member and various brackets. Guide members are formed on the other of the links and the fulcrum member, the actuator member and various brackets. In one preferred embodiment, certain of the tracks, preferably formed in the brackets, are curved.

[0030] In yet another aspect, one preferred embodiment of a seating structure includes a housing and a support member pivotally mounted to the housing. A tilt limiter member is moveably mounted to one of the housing and the support member, and a stop member is connected to the other of the support member and the housing. An actuator mechanism is coupled to one of the housing and the support member and includes a spring having a first and second arm, a drive link and a follower link. The drive link is pivotally mounted to one of the housing and the support member about a first axis and engages the first arm of the spring at a first location spaced from the first axis. The follower link is pivotally mounted to one of the housing and the support member about a second axis spaced from the first axis and engages the second arm of the spring at a second location spaced from the second axis. The follower link is pivotally coupled to the tilt limiter member.

[0031] In one preferred embodiment, the stop member has a downwardly facing stop surface and the tilt limiter has an upwardly facing bearing surface engaging the stop surface. In an alternative preferred embodiment, the stop member has at least one upwardly facing stop surface and the tilt limiter has a downwardly facing bearing surface engaging the at least one stop surface. In yet another preferred embodiment, the tilt limiter member comprises a first and second tilt limiter member moveably mounted to one of the housing and the support member, and the stop member comprises a first and second stop member connected to the other of the support member and the housing. The actuator mechanism comprises first and second springs each having a first and second arm, spaced apart first and second drive links each pivotally mounted to one of the housing and the support member about the first axis, and first and second follower links.

[0032] In another aspect, in one preferred embodiment, a kit for assembling a seating structure includes a tilt housing having a plurality of connector arrangements comprising at least a first and second connector arrangement, a first seating arrangement having a first mounting arrangement configured to be connected to the first connector arrangement, and a second seating arrangement having a second mounting arrangement configured to be connected to the second connector arrangement. In another aspect, a method of assembling a seating structure includes providing a tilt housing having a plurality of connector arrangements comprising at least a first and second connector arrangement, selecting one of a first and second seating arrangements, wherein the first seating arrangement includes a first mounting arrangement configured to be connected to the first connector arrangement, and wherein the second seating arrangement includes a second mounting arrangement configured to be connected to the second connector arrangement, and connecting the selected one of the first and second seating arrangements to the tilt housing.

[0033] In yet another aspect, the seating structure includes a tilt housing, a seating structure pivotally connected to the tilt housing and a biasing member applying a biasing force to the seating structure as the seating structure is pivoted relative to the tilt housing. An adjustment mechanism is operably connected to the biasing member and is operable to adjust the biasing force applied by the biasing member. The adjustment mechanism includes a gear housing removably disposed in the tilt housing. The gear housing is rotatably connected to the tilt housing about an axis. The gear housing includes first and second locator portions abutting the tilt housing. The first locator portion prevents the gear housing from moving relative to the tilt housing in a first direction. The second locator portion prevents the gear housing from rotating relative to the tilt housing about the axis.

[0034] In another aspect, a support member for a seating structure component includes a first support member having a first plurality of spaced apart fins and a second support member having a second plurality of spaced apart fins. The first support member is secured to the second support member with the first plurality of fins nested between the second plurality of fins. In one preferred embodiment, a back member is connected to at least one of the first and second support members.

[0035] In yet another aspect, a control device for an adjustable seating structure includes a first adjustment control positioned in an orientation approximating a seating member. The first adjustment control is moveable about a horizontal axis. A second adjustment control is positioned adjacent the first adjustment control in an orientation approximating a backrest member. The second adjustment control is moveable about the horizontal axis. The first adjustment control and the second adjustment control, in combination, generally resemble a seating structure. In one preferred embodiment, the first adjustment control and the second adjustment control are coupled to a forward tilt limiter and a rear tilt limiter respectively.

[0036] Various methods of assembling a tilt chair, and of using and adjusting a tilt chair having an adjustable fulcrum member and various tilt limiters also are provided. For example, various preferred embodiments of the seating structure include inserting an insert member into a pivot tube to deform or expand the tube so as to fixedly secure the tube to a wall or other structure. In addition, other preferred embodiments include inserting a pivot member having a key surface through a mouth of a bearing member and rotating the pivot member so as to locate the pivot member in the bearing member. In yet another preferred embodiment, a plurality of tilt housing components are disposed on an annular bushing and an end of the bushing is deformed to capture the components on the bushing.

[0037] The various preferred embodiments provide significant advantages over other tilt chairs and seating structures, including chairs and seating structures having adjustable armrests, backrests, seats and tilt controls. For example, in one preferred embodiment, an improved tilt control mechanism is provided. The resistive force of the leaf springs is easily and simply adjusted by moving the fulcrum member longitudinally within the housing. In one embodiment, a removable gear housing can be quickly easily installed without fasteners and the like for adjusting the fulcrum member. In another preferred embodiment, the configuration of the linkage assembly allows the user to quickly move the fulcrum over a wide range of longitudinal positions with minimal turns of the drive shaft. In addition, the unique shape of the support surface on the fulcrum provides a variable balancing spring rate, which results from an increasing amount of contact between the support surface and the spring as the user tilts rearwardly.

[0038] The three bar slide mechanism also provides several advantages. For example, the linkage provides for a synchrotilt chair wherein the back tilts at a greater rate than the seat, but avoids the use of a fourth bar, which can add to the complexity and manufacturing costs of the chair. Indeed, the overall design is greatly simplified by forming “bars” out of the housing, seat support and back support. Additionally, the use of a slide member allows for the assembly to be made in a more compact and aesthetically pleasing form.

[0039] The modular tilt housing also provides significant advantages. In particular, different seating arrangements can be mounted or connected to a single tilt housing with different connection configurations, thereby providing seating structures with different kinematics and appearances. At the same time, a single modular tilt housing provides significant savings and reductions in inventories. Indeed, completely different chairs operating on completely different kinematic principles can be assembled from a single tilt housing. The modular tilt housing can also be configured to support different actuation mechanisms at various mounting locations. The back support can also be configured as a modular member, wherein it is adapted to support and be coupled with different seat configurations at different connector locations, thereby providing additional flexibility in assembling different seating structures with different kinematics and appearances.

[0040] The preferred embodiments of the armrests also provide advantages. For example, the curved spine and stem provide maximum vertical adjustment, while maintaining a relatively open area beneath the seat. In addition, the height of the armrests can be adjusted quickly and easily, with the indexing member providing an audible signal to the user about the various available positions. Moreover the armrests can be laterally and pivotally adjusted quickly and easily, while the mechanism, with the interaction of gears, maintains a firm, robust feel to the user.

[0041] The preferred embodiments of the adjustable seat also provide advantages. For example, the depth of the seat can be adjusted without having to move the entire seat, or in other words, while maintaining a rear portion of the seat in the same position. Such construction avoids the need for additional support members. In addition, the adjustment mechanism can be easily grasped and manipulated the user to adjust the depth of the seat. Moreover the front portion of the seat, when bent downwardly, provides transitional support for the user's legs when sitting down or standing up from the chair.

[0042] The preferred embodiments of the tilt limiter controls also provide advantages. For example, in one embodiment, both of the forward and rearward tilt limiters are spring loaded, such that the position of each can be adjusted at any time, but with the limiter being moved only when the load is relieved from the chair. In another embodiment, the rear tilt limiter is supported by the tilt housing, which carries the load applied by the back support against the tilt limiter, which increases the overall robustness of the limiter without having to unnecessarily fortify the pivot connections of the tilt limiter. Moreover, an indexing feature provides the user with a distinct indication that an available setting has been achieved.

[0043] In addition, the orientation and/or shape of the adjustment controls provides indicia to the user about the functionality of the device or mechanism coupled to the control. For example, a first and second adjustment control can be oriented to generally resemble a seating structure, with each of the adjust controls being coupled to device or mechanism that controls the adjustment of the corresponding seating structure member, for example the seat or backrest.

[0044] The support member for a seating structure component having a first support member with a first plurality of spaced apart fins and a second support member with a second plurality of spaced apart fins also provides significant advantages. In particular, the first and second support members in combination provide substantial bending strength, yet provide torsional flexibility by way of the fins moving relative to each other. In this way, the support member, when used for example as a backrest spine, provides resistance to bending, but allows the backrest to flex torsionally about a longitudinal axis. In addition, the first and second support members can be configured to provide for the coupling of various back members and adjustment devices. For example, the first and second support members can be configured to define a gap therebetween to allow for an engagement member to be inserted therethrough wherein it can engage one of the first and second support members. In addition, the support members can be easily and cheaply manufactured by various molding processes.

[0045] The present invention, together with further objects and advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 is a perspective view of an armrest assembly.

[0047] FIG. 2 is an exploded perspective view of one embodiment of an armrest assembly.

[0048] FIG. 3 is an enlarged partial cross-sectional view of a lever and index member engaging a rack.

[0049] FIG. 4 is an enlarged partial side view of the lever and index member of FIG. 3 engaging a rack.

[0050] FIG. 5 is a perspective view of an index member.

[0051] FIG. 6 is an exploded top perspective view of one embodiment of an upper portion of armrest assembly.

[0052] FIG. 7 is a bottom view of one embodiment of an armrest support.

[0053] FIG. 8 is an exploded bottom perspective view one embodiment of a portion of an upper portion of an armrest assembly.

[0054] FIG. 9 is an enlarged partial top perspective view of one embodiment of a portion of an upper portion of an armrest assembly.

[0055] FIG. 10 is an enlarged partial top perspective view of another embodiment of a portion of an upper portion of an armrest assembly.

[0056] FIG. 11 is a perspective view of one preferred embodiment of a chair.

[0057] FIG. 12 is a front view of the chair shown in FIG. 11 .

[0058] FIG. 13 is a right side view of the chair shown in FIG. 11 , with the left side view being a mirror image thereof.

[0059] FIG. 14 is a top view of the chair shown in FIG. 11 .

[0060] FIG. 15 is a partial enlarged front view of the seat connected to the armrest.

[0061] FIG. 16 is a cross-sectional view of the armrest and seat taken along line 16 - 16 of FIG. 15 .

[0062] FIG. 17 is a top perspective view of one embodiment of a seat support assembly.

[0063] FIG. 18 is a bottom perspective view of the seat support assembly shown in FIG. 17 .

[0064] FIG. 19 is an exploded bottom perspective view of the seat support assembly shown in FIG. 17 .

[0065] FIG. 20 is an exploded top perspective view of an alternative embodiment of a seat support assembly.

[0066] FIG. 21 is a cross-sectional view of a portion of a seat support member.

[0067] FIG. 22 is a cross-sectional view of a carrier member.

[0068] FIG. 23 is rear perspective view of a backrest.

[0069] FIG. 24 is a front view of a backrest frame member.

[0070] FIG. 25 is a partial section cut and side view of the backrest frame member taken along line 25 - 25 of FIG. 24 .

[0071] FIG. 26 is an enlarged partial rear view of the backrest frame member.

[0072] FIG. 27 is a rear perspective view of a lumbar support.

[0073] FIG. 28 is a front view of a back member.

[0074] FIG. 29 is a cross-sectional view of the back member taken along line 29 - 29 of FIG. 28 .

[0075] FIG. 30 is a cross-sectional view of the back member taken along line 30 - 30 of FIG. 28 .

[0076] FIG. 31 is a perspective view of the back member.

[0077] FIG. 32 is a side view of the back member.

[0078] FIG. 33 is a rear perspective view of an alternative embodiment of a backrest.

[0079] FIG. 34 is a rear view of a back member.

[0080] FIG. 35 is a side view of the back member shown in FIG. 34 .

[0081] FIG. 36 is an alternative embodiment of a backrest frame member.

[0082] FIG. 37 is a side view of the backrest frame member shown in FIG. 36 .

[0083] FIG. 38 is a top view of the backrest frame member shown in FIG. 36 .

[0084] FIG. 39 is a partial cross-sectional view taken along line 39 - 39 in FIG. 23 .

[0085] FIG. 40 is a partial cross-sectional view of the back support connected to the tilt control housing.

[0086] FIG. 41 is a partial cross-sectional view of the seat supported by the tilt control housing track.

[0087] FIG. 42 is a partial cross-sectional view of a support column in an elevated and compressed position.

[0088] FIG. 43 is an exploded perspective view of the tilt assembly.

[0089] FIG. 44 is a top view of a fulcrum member.

[0090] FIG. 45 is a side view of the fulcrum member.

[0091] FIG. 46 is an alternative exploded view of the tilt assembly.

[0092] FIG. 47 is another alternative exploded view of the tilt assembly.

[0093] FIG. 48 is a perspective view of the actuator mechanism and linkage assembly for the fulcrum member.

[0094] FIG. 49 is an exploded view of the linkage assembly for the fulcrum member.

[0095] FIG. 50 is cross-sectional view of the linkage assembly for the fulcrum member.

[0096] FIG. 51 is an exploded view of the tilt control housing and stop members.

[0097] FIG. 52 is an exploded perspective view of a tilt limiter mechanism.

[0098] FIG. 53 is a perspective view of the back support and tilt limiter assembly.

[0099] FIG. 54 is an exploded perspective view of the back support and tilt limiter assembly.

[0100] FIG. 55 is a partial cross-sectional view of the back support secured in a forward tilt position.

[0101] FIG. 56 is a partial cross-sectional view of the back support secured in an at-rest neutral position.

[0102] FIG. 57 is a partial cross-sectional view of a portion of the tilt limiter mechanism.

[0103] FIG. 58 is a perspective view of one embodiment of a tilt assembly and back support with the springs in a disengaged position.

[0104] FIG. 59 is a side view of one embodiment of a tilt assembly and back support with the springs in a disengaged position.

[0105] FIG. 60 is an exploded perspective view of on embodiment of a tilt assembly and back support.

[0106] FIG. 61 is a front view of one embodiment of the fulcrum member.

[0107] FIG. 62 is a side view of the fulcrum member shown in FIG. 61 .

[0108] FIG. 63 is a side view of a rear tilt limiter.

[0109] FIG. 64 is a partial cross-sectional view of a tilt limiter drive member.

[0110] FIG. 65 is a perspective view of a forward tilt limiter.

[0111] FIG. 66 is a perspective view of an outer tilt housing member.

[0112] FIG. 67 is a perspective view of an inner tilt housing member.

[0113] FIG. 68 is a perspective view of a tilt housing guide member.

[0114] FIG. 69 is an exploded perspective view of an actuation mechanism.

[0115] FIG. 70 is a side view of a gear housing.

[0116] FIG. 71 is a cross-sectional view of one embodiment of the connection between the seat and armrest.

[0117] FIG. 72 is an exploded perspective view of a lumbar support assembly.

[0118] FIG. 73 is an exploded perspective view of a backrest assembly.

[0119] FIG. 74 is front view of a back member.

[0120] FIG. 75 is a partial cross-sectional view of a back member taken along line 75 - 75 of FIG. 74 .

[0121] FIG. 76 is a partial cross-sectional view of a back member taken along line 76 - 76 of FIG. 74 .

[0122] FIG. 77 is a partial cross-sectional view of a portion of a back member.

[0123] FIG. 78 is a cross sectional view a back support member.

[0124] FIG. 79 is a partial rear view of a lumbar support member.

[0125] FIG. 80 is a partial cross-sectional view of the seat supported by the tilt control housing.

[0126] FIG. 81 is an exploded perspective view of a seat adjustment mechanism.

[0127] FIG. 82 is an exploded perspective view of one embodiment of a seat support assembly.

[0128] FIG. 83 is a partial exploded perspective view of one embodiment of an armrest assembly.

[0129] FIG. 84 is an exploded perspective view of one embodiment of an upper portion of an armrest assembly.

[0130] FIG. 85 is a cross sectional view of one embodiment of an armrest assembly.

[0131] FIG. 86 is a cross-sectional view of one embodiment of an armrest assembly.

[0132] FIG. 87 is front view of an armrest sleeve member.

[0133] FIG. 88 is an exploded perspective view of a backrest assembly.

[0134] FIG. 89 is a side view of a back support member.

[0135] FIG. 90 is a cross-sectional view of the back support member taken along line 90 - 90 of FIG. 89 .

[0136] FIG. 91 is a front view of a back support member.

[0137] FIG. 92 is a cross-sectional view of the back support member taken along line 92 - 92 of FIG. 91 .

[0138] FIG. 93 is a side view of a back support fulcrum member.

[0139] FIG. 94 is a partial top view of the back support fulcrum member shown in FIG. 93 .

[0140] FIG. 95 is front view of a back member with a cut-out therein.

[0141] FIG. 96 is a front view of the back member shown in FIG. 95 with a hinge portion overmolded thereon.

[0142] FIG. 97 is a partial cross-sectional view of the back member taken along line 97 - 97 of FIG. 96 .

[0143] FIG. 98 is a side cross-sectional view of the tilt assembly with the seat and back in an upright position.

[0144] FIG. 99 is a side cross-sectional view of the tilt assembly with the seat and back in a rearward tilt position.

[0145] FIG. 100 is a side cross-sectional view of the tilt assembly prior to engaging the springs with the spring link.

[0146] FIG. 101 is a graph of applied and restoring torques v. recline angle for three users.

[0147] FIG. 102 is an enlarged partial side view of the seat and backrest.

[0148] FIG. 103 is a front view of an alternative embodiment of a back member.

[0149] FIG. 104 is an Angle v. Torque graph for light users.

[0150] FIG. 105 is an Angle v. Torque graph for heavy users.

[0151] FIG. 106 is a back angle v. torque curve.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0152] General:

[0153] The terms “longitudinal” and “lateral” as used herein are intended to indicate the direction of the chair from front to back and from side to side, respectively. Similarly, the terms “front”, “side”, “back”, “forwardly”, “rearwardly”, “upwardly” and “downwardly” as used herein are intended to indicate the various directions and portions of the chair as normally understood when viewed from the perspective of a user sitting in the chair.

[0154] Referring to the drawings, FIGS. 11 and 12 show a preferred embodiment of the chair having tilt control housing 10 , seat 200 , back support 304 and back 302 . It should be understood that the term “housing” generally refers to any support member that supports another member, and includes, but is not limited to a structure that provides an enclosure. A pair of armrests 400 extend from, move with and define a portion of the back support 304 . Preferably, the back support 304 is pivotally mounted to the control housing 10 , and the seat 200 is pivotally mounted to the back support 304 via a pivot axis located on the armrests 400 at the approximate hip joint of the user above the seating surface. The seat 200 is further slideably and pivotally supported by the tilt control housing.

[0155] It should be understood that the terms “mounted,” “connected”, “coupled,” “supported by,” and variations thereof, refer to two or more members or components that are joined, engaged or abutted, whether directly or indirectly, for example, by way of another component or member, and further that the two or more members, or intervening member(s) can be joined by being integrally formed, or by way of various fastening devices, including for example and without limitation, mechanical fasteners, adhesives, welding, press fit, bent-over tab members, etc.

[0156] In operation, the housing 10 , seat 200 and back support 304 , with the armrests 400 , form a three-bar linkage with a slide. It should be understood that the term “slide,” as used herein, refers to two members that translate relative to each other, whether by direct sliding or by rolling. Preferably, the pivot axis formed between the seat 200 and housing 10 is positioned forwardly of the pivot axis formed between the back support 304 and housing 10 , which axis is positioned forwardly of the pivot axis formed between the back support 304 and the seat 200 , such that the backrest 300 and back support 304 tilt rearwardly at a greater rate and angle than does the seat 200 . Preferably, the back tilts relative to the seat at about a preferred 2:1 ratio, such that the shirt-tail pull effect is avoided. Of course, other synchrotilt ratios are contemplated and suitable. In addition, the configuration of the back support, the seat and the various positions of the pivot axes, allow the seat to pivot about the ankles of a user seated in the chair, preferably without the front edge of the seat rising as the user tilts rearwardly. The three-bar linkage provides a simple and compact mechanism that avoids the use of additional links. Additionally, by forming the linkage assembly from the seat, back support and housing, complex and expensive links and load bearing parts are avoided.

[0157] An adjustable support column 12 , preferably pneumatic and shown in FIG. 42 , is mounted to a rear portion of the housing 10 at opening 14 . A top portion of the column 12 , having a side-actuated lever 16 , extends into the housing, and preferably is fitted inside a bushing 50 that captures and connects the various tilt control housing components. A cable 18 is connected to the lever, and can be moved within a guide to actuate the lever. An opposite end of the cable is engaged by an arm on a pivot tube 22 , shown in FIGS. 43 and 60 . A grippable handle 24 , or paddle, extends from the tube. In operation, the user rotates the paddle 24 and thereby moves the cable 18 to actuate the lever 16 , which in turn allows the support column 10 to extend in response to a gas spring contained therein, or to collapse in response to the weight of the user being applied to the seat. One suitable support column is available from Samhongsa Co. Ltd., otherwise referred to as SHS.

[0158] Referring to the embodiment of the adjust mechanism for the support column shown in FIGS. 60 and 69 , the tube 22 (which is rotated 180 degrees in FIG. 60 ) has a flared end 802 . The end 802 of the tube is configured to matingly engage a first end 806 of a pivot member 804 . The pivot member 804 has a second end 808 that is rotatably received on a hub 812 of gear 810 . A clip 819 secures the end 808 to the hub 812 . The pivot member includes an arm 814 that extends perpendicular from a tube portion of the pivot member. The arm includes an end portion that engages end of the cable 18 . A spring 816 biases the pivot member to a return position. In operation, the user moves the paddle 24 , which rotates the tube 23 and the pivot member 804 . As the arm 814 of the pivot member is moved, it moves the cable 18 relative to the guide, and thereby actuates the support column.

[0159] Referring to FIGS. 11 and 12 , a base 26 , preferably a five arm base with casters, is mounted to the bottom of the support column 12 in a conventional manner, although one of skill in the art would understand that other support columns and bases can be used to support the housing, including fixed height support columns and non-rolling bases, including for example a base configured with glides.

[0160] With the chair being generally described, the various features of the armrests, the seat, the backrest and the tilt control assembly, along with various controls therefore, will be described in more detail below.

[0161] Armrest Assembly:

[0162] Referring to FIGS. 1, 2 and 58 - 60 , one preferred embodiment of an armrest assembly 400 is shown as having a lower portion 402 and an upper portion 404 . The lower portion 402 includes a lower support member having a laterally extending, and substantially horizontal portion 406 and an upper spine portion 408 extending upwardly and outwardly from the horizontal portion 406 . The spine portion 408 is preferably curved and defines a curvature substantially in a plane substantially parallel to the torso of the user. In one preferred embodiment, shown in FIGS. 1 and 2 , the spine 408 has a lower curved portion 410 and an upper curved portion 412 , with the upper curved portion having a smaller cross-section, which is preferably rectangular, than the lower curved portion. Preferably, the lower portion is made of 380 cast aluminum or any other suitably strong material, such as metal, including steel, or fiberglass, plastic, composites and other similar materials.

[0163] As shown in FIGS. 1, 2 , 71 and 87 , a pair of sleeve members 414 are disposed on the upper curved portion 412 and define a cross-section substantially the same as the lower curved portion. Referring to the embodiment of FIGS. 58-59 and 87 , notches 413 locate the sleeve members 414 on the curved portion 412 by way of a locator tab 415 . It should be understood that the sleeve members can be made as a single member that is disposed over the end of the spine 408 .

[0164] As best shown in FIGS. 13 and 58 - 60 , the ends of the lower horizontal portions 406 extend through openings 306 in opposite sides of a back support 304 and are secured, preferably fixedly (for example by welding), one to the other and/or to the back support member. Alternatively, the lower portions can be moveably secured to and supported by the back support, so as to allow them to move inwardly and outwardly in the lateral direction. In either embodiment, the lower portions 402 of the armrests form part of the back support 304 . The lower portions of the armrests can be configured in any number of shapes, and provide different mounting pivot locations for the seat. For example, the shape and size of the armrest can be varied to provide different mounting arrangements and locations for the seat. Alternatively, a single modular armrest can be configured with a plurality (meaning two or more) mounting arrangements on the same member. In the preferred embodiment, the spine portion of the back support 304 can be made as a modular element, with the overall configuration of the back support being quickly and easily reconfigured simply by providing a different lower portion of the armrest.

[0165] Referring to the embodiments shown in FIGS. 1 and 71 , an opening 416 is formed through the upper curved portion 404 and is shaped to receive a pivot member 418 , 818 , which secures the seat 200 to the spine 408 , as shown in FIGS. 15 and 71 .

[0166] Referring to FIGS. 2 and 87 , the sleeve members 414 are preferably U-shaped, having an inner and outer wall 420 , 422 joined by an end wall 424 . In the embodiment shown in FIG. 2 , a cut-out 426 in the inner wall is shaped to receive the pivot member 418 once the sleeve members 414 are installed on the upper portion of the spine. Referring to the embodiment of FIG. 87 , the inner wall is formed from a plurality of flexible tab members. Some of the tab members 417 have an inner surface that is raised above the surface of other of the tab members 419 . The tab members are biased against the curved portion 412 and take up the tolerances.

[0167] Referring to FIGS. 2-4 , 71 and 87 , a rack 428 is formed on the outer wall 422 . The term “rack” as used herein broadly means a series of engageable elements, including for example and without limitation, teeth, grooves, slots, openings, protuberances, etc. Referring to FIGS. 3 and 4 , the profile of the rack 428 includes a plurality of curved engagement portions 430 , and a plurality of teeth portions 432 interspaced between the curved portions, with a plurality of sloping recesses 434 and slots 436 defining the profile of the rack, which provides unique positions for positive latch engagement.

[0168] Referring to FIGS. 71 and 87 , the profile includes a plurality of first and second recesses 435 , 437 . Preferably, the profile extends laterally across the entirety of the face of the outer wall 422 . In one preferred embodiment, the sleeves are made of acetal.

[0169] Referring to FIGS. 2 and 87 , one of the sleeve members 414 (female) has a plurality of recesses 438 formed in the end of the free edge 442 of the inner and outer walls, while the other sleeve (male) has a plurality of protuberances 440 extending from the end of the free edge 442 , with the protuberances 440 shaped to be received in the recesses 438 when the free edges 442 are abutted as the sleeve members 414 are installed on the spine 408 . In this way, the sleeve members 414 are prevented from moving longitudinally relative to one another along the spine.

[0170] Referring to FIGS. 3 and 4 , in one preferred embodiment, the sleeve members 414 each include a flange 444 formed along the free edge of the outer wall, with the recesses or protuberances formed in the face of the flange. The outer edge 446 of the flange includes a plurality of indexing notches 448 that form a rack 450 and are spaced longitudinally along the flange approximately the same distance as the engagement portions 430 of the rack 428 .

[0171] Referring to FIG. 2 , the sleeve members 414 each include a plurality, meaning two or more, bearing pads 452 on the end walls and inner walls that extend outwardly from the wall and slidably engage the curved upper members 404 . Alternatively, the sleeves can include roller bearings that engage the curved member.

[0172] In one preferred embodiment, the radius of the inner surface of the lower curved portion 410 and of the inner wall of the sleeve members 414 is approximately 13.78 inches, while the radius of the outer surface of the lower curved portion 410 and of the outer wall of the sleeve member is approximately 14.68 inches. Of course, it should be understood that other radii would also work, and that preferred radius is between about 12 and about 16 inches.

[0173] Referring to FIGS. 1, 2 , 15 and 83 , the upper portion 404 forms a stem 454 that includes a housing 456 forming a cavity 458 , which is shaped to receive the curved spine 408 and sleeve member 418 . The cavity 458 is defined by an inner and outer wall 460 , 462 , and a pair of end walls 464 . The stem 454 has approximately the same curvature as the spine 408 , such that it can slide therealong without binding. For example, in one preferred embodiment, the radius of the inner surface of the outer wall 462 of the cavity is approximately 14.73 inches, and preferably between about 12 and 16 inches. An elongated opening 416 , or slot, is formed in the inner wall 460 and is shaped to receive the pivot member 418 , such that the stem 454 can be moved relative to the spine 408 without interfering with the pivot member. An opening 466 is also formed in the outer wall 462 so as to expose the racks 428 of the sleeve members disposed on the spine.

[0174] Referring to FIGS. 2-4 , 83 and 85 , a latch mechanism 468 is pivotally secured to the outer wall 462 of the stem and is received in the opening 466 . Referring to the embodiment of FIGS. 2-4 , the latch mechanism 468 includes a lever member 470 and an index member 472 pivotally mounted to the stem 454 with a pivot pin 474 at a substantially horizontal pivot axis. The index member 472 is nested or pocketed in the lever member 470 , as shown in FIGS. 3 and 4 . It should be understood that the lever and index member can be integrally formed as a one-piece member. In the embodiment of FIG. 83 , the index member is omitted. Referring to FIGS. 2 and 83 , the lever member 470 includes a grippable handle portion 476 that extends downwardly from the pivot axis and is nested in a recess 478 formed in the stem. The recess 478 extends below the end of the lever so as to allow the user to insert a finger and grip or lift the lever member 470 from an engaged position to move it to a disengaged position. Referring to FIGS. 3 , and 4 , the lever member 470 further includes an engagement portion 480 that extends inwardly and engages one of the curved engagement portions 430 of the rack when the lever is in the engaged position. The engagement portion has a curved surface that translates relative to the sloping surface of the recess 434 as the lever is moved between the engaged and disengaged positions. The lever has a cavity 482 shaped to receive the index member 472 and includes a pair of shoulders 484 that mate with and abut corresponding shoulders 486 on the index member, such that the index member is pivoted about the pivot axis 474 with the lever member.

[0175] Referring to FIGS. 83, 85 and 86 , a primary engagement portion 481 is shaped to be received in the recess 435 , while a secondary engagement portion 483 is received in the recess 437 . The lever further includes a stop portion 485 that engages an upper edge 487 of the stem when the lever is in the unlatched position. A spring 491 is disposed about the pivot pin 474 and is engaged between the lever 470 and the stem 454 so as to bias the lever to an unlatched position. The lever 470 acts as an over-center toggle, such that it snaps into the latched position when it is moved into engagement with the rack. A portion of the lever and/or a portion of a spring can index with the rack as the upper arm portion is moved to the desired position.

[0176] Preferably, the lever 470 , sleeve members 414 and stem 454 are made of a SG95 or SG200 Urethane, 79-80D Durameter. Alternatively, those components can be made from various plastics, metals, elastomers, composites, fiberglass, etc.

[0177] Referring to the embodiment of FIGS. 2 and 3 , the index member includes a bumper portion 488 having a concave surface shaped to engage the curved portion 430 when the lever is in the engaged position. Preferably, the index member 472 is made of 2140 Urethane, 55-65D Durameter, although it should be understood that it can be made of other plastics, metal, fiberglass, rubbers, composites and the like, or combinations thereof. The index member 472 further includes a flexible, resilient indexing finger 490 that extends outwardly from the index member. The indexing finger 490 is disengaged from the rack 450 when the lever is in the engaged position. As the lever 470 is moved to the disengaged position, the indexing finger 490 is pivoted into abutment with the flange 444 of the sleeve, and selectively engages the notches 448 of the rack 450 as the stem 454 is moved relative to the spine 408 . The indexing finger 490 will selectively engage one of the notches 448 as the lever is moved from the engaged to the disengaged position and before the stem is moved relative to the spine. As the stem is moved relative to the spine, the indexing member 472 successively, selectively engages the notches 448 and provides an audible indexing sound to indicate to the user that an available vertical position has been selected. The lever 470 can then be pivoted from the disengaged position to the engaged position to again secure the stem 454 to the spine 408 and prevent movement therebetween.

[0178] It should be understood that the racks could be formed on the stem, and with the lever and/or indexing members pivotally mounted to the spine.

[0179] Referring to FIGS. 1, 2 , 6 - 10 and 83 , the upper portion 404 of the armrest assembly provides lateral and pivotable adjustment of an armrest. Referring to FIGS. 2, 6 and 83 , the upper end of the stem forms a mounting platform 492 , which has a guide member 494 , or pivot member, extending upwardly therefrom and defining a substantially vertical pivot axis 504 . The term “platform” as used herein means any support structure or surface, and includes, but is not limited to, a substantially flat, horizontal member or surface, or platelike member. In addition, a protuberance 496 , or detent extends from the mounting platform 492 at a location spaced from the guide member 494 . The detent can be spring loaded.

[0180] Referring to FIGS. 2 , 6 - 10 and 84 , a support platform 498 includes an opening 500 that is shaped to receive the guide member, with the platform disposed on the guide member at the opening such that the platform can pivot about the pivot axis. Referring to the embodiment of FIGS. 2 and 6 - 10 , the platform 498 includes a plurality of recesses 502 formed on a bottom surface thereof and spaced from the opening so as to be aligned with the protuberance. The plurality of recesses 502 form an array thereof having a curvature generally centered around the pivot axis 504 .

[0181] In the embodiment of FIG. 84 , the protuberance 496 extends through an opening 503 formed in the platform and is indexed in a slot 505 formed in a platform 506 by a pair of arms 507 that have end portions 515 that are shaped to define three openings 509 . Of course, more openings could be formed and defined by the slot and arms. A rubber or elastomeric spring 511 is disposed in a slot 513 formed opposite slot 505 . The spring 511 biases the arms 507 against the protuberance.

[0182] In operation of the embodiment shown in FIGS. 2 and 6 - 10 , the platform 498 is moved or pivoted about the pivot axis 504 relative to the mounting platform 492 , with the protuberance 496 indexing with one of the plurality of recesses 502 so as to locate the platform 498 relative to the mounting platform 492 in a plurality of pivot positions corresponding to the plurality of recesses. In the operation of the embodiment shown in FIGS. 84 , the platform is moved or pivoted about the pivot axis 504 relative to the mounting platform 492 , with the protuberance 496 indexing with one of the plurality of openings 509 so as to locate the platform 498 relative to the mounting platform 492 in a plurality of pivot positions corresponding to the plurality of recesses. A bearing member can be disposed on the protuberance, with the bearing member indexing with the openings.

[0183] It should be understood that the location of the recesses (or openings) and protuberance can be reversed, with the protuberance extending downwardly form the platform and with the array of recesses or openings formed in the mounting platform on the top of the stem. Likewise, it should be understood that an array of protuberances could be provided on one or the other of the platforms and which mate with a recess.

[0184] Referring to FIGS. 2 and 84 , the first platform 498 is secured to another second platform 506 . As shown in one embodiment of FIG. 8 , the platform 506 has a recess formed in a bottom portion thereof that is shaped to receive the raised indentations 510 that form the array of recesses 502 on the bottom side of the platform. Referring to FIGS. 2 and 84 , the platform 506 has an opening 512 formed on one end thereof that is shaped to receive the guide member 494 . A second opening 514 , 516 is formed on an opposite end of each of the platforms 506 , 498 . Referring to FIG. 2 , fastener 518 extends through the second openings and secures the platforms one to the other. Alternatively, a boss can be formed on the platform 498 , with the boss extending into a boss formed in platform 506 and through opening 514 . A fastener, and one or more washers, extends downwardly through the platform 506 and is engaged with the boss to secure the platforms 498 and 506 together.

[0185] In a first embodiment of the platform 506 , shown in FIG. 2 , the platform includes a recess or channel 520 formed across an entire width thereof. A pair of spaced apart and parallel linear gears 522 , or racks, define the opposite side walls of the channel. An armrest support 526 , shown in FIGS. 2 and 7 , includes a pair of axles 528 that define a pair of spaced apart axes of rotation. A pair of pinion gears 524 are mounted to the armrest support on the axles 528 and are disposed in the channel 520 , such that each of the pinion gears mesh with each other and one of the linear gears 522 respectively.

[0186] In a second embodiment, shown in FIGS. 6, 8 and 84 , the platform has only a single linear gear 522 , with an opposite wall of the channel 520 being preferably substantially smooth. The armrest support has only a single axle 528 defining an axis of rotation. A single pinion gear 524 is rotatably mounted on the axle 528 within the channel and meshes with the linear gear 522 .

[0187] In either embodiment, as shown in FIGS. 2, 6 , 8 and 84 , the armrest support 526 includes a pair of spaced apart and substantially parallel tracks 530 , shown as slots, formed therethrough. One of the tracks 530 receives the guide member 494 extending upwardly from the stem through the platforms 498 , 506 , while the other receives a guide member 532 formed on an upper surface of the platform 506 , and through which the fastener 518 passes to secure the platforms 498 , 506 . In operation, the user moves the armrest support 526 laterally relative to the platform 506 , such that in one preferred embodiment, the pinion gears 524 mesh with each other and with the linear gears 522 , or in another preferred embodiment, the single pinion gear 524 meshes with the single linear gear 522 , as the guide members 494 , 532 ride in the tracks 530 . The interaction between the pinion gear(s) 524 and linear gear(s) 522 provides a firm solid feel as the armrest support 526 is moved in the lateral direction and is guided by the guide members riding in the tracks. In the embodiment of FIGS. 6, 8 and 84 , the platform 506 includes an additional pair of guides 534 , configured as posts, that extend upwardly therefrom and are received in a track 536 or channel formed in the armrest support 506 .

[0188] It should be understood that the various guide members and tracks could be formed in either the platform or armrest support. Likewise, the channel and linear gear(s) could be formed in the armrest support, with the pinion gear(s) secured to the platform. Also, it should be understood that the upper and lower platforms 498 , 506 can be made as a single, one-piece member, with the recesses or protuberances formed on one side thereof, and with the channel and linear gear(s) formed on the other side thereof.

[0189] Referring to FIGS. 2, 9 , 10 and 84 , a pawl member 538 is shown as being pivotably mounted to the armrest support 526 about a pivot axis 540 . The pawl member can be secured to the pivot member 540 with a retainer member. In the embodiment of FIGS. 2 and 10 , the pawl 538 includes a first arm 542 having an end portion 544 defining one or more teeth or engagement portions that are shaped to engage one or more teeth on one of the pinion gears 524 . Preferably, the pawl is pivotally mounted to a top surface of the support 526 , with the end portion 544 extending through an opening 545 in the support to engage the one or more teeth on the pinion gear(s). The pawl further includes an opening 546 , elongated or circular, formed opposite the end portion and a second arm 548 extending substantially perpendicular to the first arm. Referring to the embodiment of FIG. 10 , a track 550 or slot having a radius about the pivot axis 540 is formed in an end portion of the arm 548 and is shaped to receive a post or guide 552 extending upwardly from the armrest support.

[0190] A push button 554 includes a flange portion 556 that is slideably mounted in a pair of tabs that form a track 558 . The button has an arm extending from the flange that includes a post 560 received in the opening 546 of the pawl. A spring 562 is mounted to the armrest support and biases the end portion 544 of the pawl into engagement with at least one of the teeth on at least one of the pinion gears 524 . Alternatively, or in combination therewith, a pair of springs 549 bias the push button away from the platform as they engage a pair of backstops 551 .

[0191] In the embodiment of FIGS. 9 and 84 , the pivot axis is formed at the junction of the first and second arm 538 , 542 , with the post 560 engaging the opening 546 or track in an end portion of the arm 548 .

[0192] In the operation of either embodiment, the user pushes the push button 554 inwardly as it slides within the track 558 so as to move the post member 560 laterally inward. The post member 560 rotates the pawl 538 against the force of the spring 562 , 549 about the pivot axis 540 and moves the end portion 544 thereof away from the teeth of the pinion gear(s) 524 to a disengaged position. When the desired lateral location of the armrest support is reached, the user releases the button 554 , thereby allowing the spring 562 , 549 to bias the pawl 538 to an engaged position with at least one of the pinion gear(s) 524 . In the engaged position, the pawl 538 prevents the pinion gear(s) 524 from rotating about the axis, so as to prevent the armrest support 526 from being moved in the lateral direction.

[0193] It should be understood that a lever or actuator other than the push button can be employed to move the pawl from the engaged to disengaged position. Likewise, it should be understood that the pawl can be moved along a linear, rather than a rotational, path between the engaged and disengaged positions.

[0194] Referring to FIG. 2 , a fastener 564 secures the armrest support 526 and the platforms to the guide member 494 and stem 454 . In this way, the armrest support 526 pivots with the platforms 498 , 506 about the guide member 494 as the armrest support is moved to the desired pivot position. A pad 566 , preferably foam, and substrate 568 are secured to the armrest support with various fasteners and/or adhesive. The pad also can include various gels or other fluids and/or gases to provide a comfortable feel to the user's arm, which rests thereon. Preferably, the push button, or other actuator, is received in an opening or recess formed in the pad, and is configured with an outer contour shaped to mate with the outer contour of the pad.

[0195] Backrest:

[0196] Referring to FIGS. 11-13 and 23 - 32 , a first embodiment of a backrest 300 includes a backrest frame member, or back support member 304 , and a back member 302 . The support member 304 , otherwise referred to as a frame me