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AssigneeHerman Miller, Inc.
InventorsWilliam E. Stumpf, Rodney C. Schoenfelder, Donald Chadwick, Carolyn Keller, Timothy P. Coffield, Randy J. Sayers, Jeffrey W. Bruner, George A. Miles, Eric Cammenga, Philip Crossman
Estimating the term…
An apparatus for controlling the tilt range of a chair and the resistance to tilting of the chair including a torsion spring mounted to an axle, a tilt rate adjustment mechanism, a forward tilt limiter and a rearward tilt limiter. The tilt rate adjustment mechanism includes an outer sleeve member mounted to the spring. An arm extends radially outward from the sleeve and operably engages a block member threadably attached to a screw. A first and second gear member are actuated to rotate the screw so as to move the block member which thereby moves the arm a desired amount to adjust the initial return torque of the spring. The forward tilt limiter includes an arm extending outwardly from the axle. The arm operably engages a pivot member pivotally attached to a tilt control housing. The rearward tilt limiter also includes an arm extending outwardly from the axle. The arm operably engages a cam member pivotally attached to the tilt control housing.
An apparatus for controlling the tilt range of a chair and the resistance to tilting of the chair, comprising:
A tilt limiter mechanism for a chair comprising:
A tilt limiter mechanism for a chair comprising:
A tilt limiter mechanism for a chair comprising:
A tilt control mechanism for a chair comprising:
A tilt limiter mechanism for a chair comprising:
A tilt limiter mechanism for a chair comprising:
A tilt limiter mechanism for a chair comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles: positioning or centering articles in the…
Having independently-adjustable supporting parts: the parts being arm-rests
The parts being arm-rests: adjustable rectilinearly in vertical direction
Having adjustable and lockable inclination: by means of peg-and-notch or pawl-and-ratchet mechanism
Term ended 30 Jun 2015 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The present invention relates generally to office chairs, and more particularly, to a height-adjustable, tiltable office chair which supports the body of a user in ergonomically desirable positions for performing various tasks.
Office chairs are typically configured to allow tilting of the seat and backrest as a unit or 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 acting on the legs and back of the user. These shear forces tend to cause an uncomfortable pulling of the user's clothing. In an attempt to compensate, for these shear forces, some office chairs include a backrest which pivots while the seat tilts, such as those disclosed in U.S. Pat. Nos. 2,859,801 (Moore) and 4,429,917 (Diffrient). To provide a chair which naturally conforms to the pivotal movement of both the legs and trunk of a user between tilt positions, it is desirable to provide a chair having a seat and backrest which pivot generally about the axis of the hip joints of the user.
To further ensure comfortable tilting between tilt positions and enhance the comfort of a user while in a given tilt position, it is desirable to provide a chair having a tilt mechanism with an effective pivot point about the ankles of the user. Such an ankle tilt feature decreases the effort required to tilt the chair, reduces the pressure of a forward edge of the seat acting on the underside of a user's leg, and allows the feet of the user to remain flat on a floor.
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.
FIG. 1 is a perspective view of a preferred embodiment of a chair having a backrest, a seat, and a pair of armrests.
FIG. 2 is a front view of the chair.
Referring to the drawings, FIGS. 1-7 show a preferred embodiment of a chair 30 in a middle tilt position. The chair 30 includes a seat 32, a backrest 34, and a pair of armrest assemblies 36. The seat 32 and backrest 34 are connected to a tilt control housing 38 by a linkage assembly 40. The tilt control housing 38 is mounted on a vertically adjustable, dual stage support column 42 which is secured to the center of a pedestal 44. The pedestal 44 is movably supported on a floor 46 by a plurality of casters 48 or the like.
In a preferred embodiment of the invention, the linkage assembly 40 includes a pair of first links 50 pivotally attached to upwardly extending side portions 52 of a seat frame 33 at pivot points 54 to define a pivot axis at substantially the hip joints of a user. A pair of second links 56 each have a substantially straight first section 58 to which the first links 50 are fixedly attached and a second section 60 angled downwardly from the first section 58. An upwardly extending rear end portion 62 of each first section 58 is connected to a frame 64 of the backrest 34, and an inwardly extending front end portion 66 of each second section 60 is pivotally mounted to a forward portion of the tilt control housing 38. Thus, the rigidly connected first links 50 and second links 56 act as two bars of a four bar linkage which creates an effective pivot point 68 at substantially the ankles of a user having feet resting on the floor 46.
As best shown in FIGS. 8-10, the seat 32 and backrest 34 both pivot about the hip pivot points 54 while simultaneously tilting rearwardly. To limit tilting of the seat 32, linkage assembly 40 includes a pair of restraining links 70 which form a four bar linkage in conjunction with the first links 50 and second links 56. The restraining links 70 have one end 72 pivotally attached to a front portion of the tilt control housing 38 rearwardly and below the attachment of the end portions 66 of the links 56 to the housing 38. Another end 74 of the restraining links 70 is pivotally attached to a corresponding clevis 76 extending downwardly from a rear edge of the seat 32. Thus, the seat 32 pivots about hip pivot point 54 since it is pivotally mounted to the first links 50, and the backrest 34 pivots about the same pivot point 54 since the second links 56 are fixedly connected to the first links 50. In addition, the seat 32 and backrest 34 simultaneously pivot about pivot point 66, and the restraining links 70 cause the seat 32 to pivot about the effective pivot axis 68 at the ankles of a user.