An adjustable chair comprises chair support, backrest, a backrest support mechanism including at least one backrest arm pivotally connected to the support, and a seat having front and rear regions and a seat surface. The chair includes first and second seat support mechanisms with the first mechanism adjustably connecting the front region of the seat and the second mechanism adjustably connecting the rear region. The second seat support mechanism includes at least one seat arm having front and rear arm extensions and connected to the support for pivotal movement about a horizontal axis. The rear arm extension is pivotally connected to the rear region of the seat. A toggle arrangement is pivotally mounted on the chair support and engages the front end section of the at least one seat arm and front end section of the at least one backrest arm.

A chair assembly includes a base assembly, a seat assembly having a pair of side edges and a fore-to-aft extending longitudinal centerline, a back assembly movable between upright and reclined positions, and an arm assembly including an arm base extending from a first location between the side edges to a second location laterally outward of one of the side edges, wherein the arm base extends at an acute angle with respect to the longitudinal centerline and at an upward angle from the first location toward the second location, a support assembly supported by and extending upwardly from the arm base, and an armrest supported by the support assembly that is adjustable to support the armrest between a plurality of selected vertical positions, wherein the arm assembly and back assembly move at a different rate from one another as the back assembly is moved between the upright and reclined positions.

A chair back assembly includes a back shell member including laterally extending top, bottom and side portions cooperating to define an open space therebetween, where a portion of the back shell member is located in a lumbar region, a cover having a first surface and a second surface opposite the first surface, wherein the cover covers at least a portion of the open space, and a back frame assembly operably supporting the back shell member and movable between upright and reclined positions, wherein the back frame assembly causes the back shell to flex in a fore-to-aft direction as the back frame assembly is moved between the upright and reclined positions independent of an external force being exerted on the back shell member, and where the lumbar portion of the back shell member remains spaced from the back frame as the back frame is moved between the upright and reclined positions.

Chairs, seating systems, chair sub-assemblies and sub-systems, and associated methods of assembly and use. Aspects relate to chairs and methods of assembling chairs including chair controls of a relatively compact and effective design with desirable synchronous raising and tilting motions. Aspects also relate to tilt lock assemblies for achieving secure and effective tilt securement. Additional aspects relate to forward and rearward adjustment, or extension and retraction, of a seating assembly of the chair.

A chair back height adjustment mechanism comprises a guide having an abutment surface at a lateral side of the guide which extends along an adjustment direction. The chair back height adjustment mechanism comprises an adjusting device supported on the guide so as to be displaceable along the adjustment direction. The adjusting device comprises a carrier, a coupling member which is moveably supported on the carrier, and a bias mechanism. The coupling member has a contact face shaped to abut on the abutment surface of the guide and a slanted face. The bias mechanism is operative to apply a force onto the slanted face to urge the contact face of the coupling member against the abutment surface of the guide.

An adjustable chair has a seat and a splat. The seat has a lower base, an upper base, a tilt adjusting device, a lower rotating shaft, and an upper rotating shaft. The lower base has an assembling space. The upper base is movably deposited on the lower base. The tilt adjusting device is deposited in the assembling space. The lower rotating shaft is rotatably deposited in the lower base and connected to the tilt adjusting device. The upper rotating shaft is deposited in the upper base. The splat is tiltably connected to the seat and has a backrest unit and two connecting legs. The backrest unit is deposited at a rear side of the seat. The connecting legs are connected to the backrest unit, are connected to the lower rotating shaft, and are pivotally connected to the upper rotating shaft.

The invention relates to a chair which functions by means of a deflection that is mutually synchronous between a backrest (9) and a seat (25) over a range between a respective zero position of back inclination (R.sub.0) and of seat inclination (S.sub.0) and a respective maximum back inclination (R.sub.max) and maximum seat inclination (S.sub.max). The mechanism (2) that causes synchronous deflection has a spring unit (6) arranged therein. The base support (50) of a carrier unit (5) is rigidly fastened to the underframe (1), which is intended to be set on the floor. A stationary first axis of rotation (D1) and a stationary second axis of rotation (D2) extend through the base support (50). A back carrier (91) is articulated on the first axis of rotation (D1). A third axis of rotation (D3), which moves around the first axis of rotation (D1) when the mechanism (2) is adjusted, extends through the back carrier (91). A base plate (3) lies movably on the base support (50) at the front of the base plate and is articulated on the third axis of rotation (D3) at the rear of the base plate. The base support (50) is designed in the shape of a U, having a center part (54) and two arms (53) extending upward from the center part, which arms each have a shaped piece (55) protruding upward, which shaped pieces each engage in an associated opening (34) in the base plate (3). When the mechanism (2) is deflected, a relative displacement between the stationary shaped pieces (55) and the openings (34) arises. The two openings (34) are oriented in the direction of the seat depth (T) and thus at right angles to the transversely extending axes of rotation (D1, D2, D3).

Dynamic furniture for supporting a seated or reclining user includes a base, an actuator assembly supported by the base, a front boom in circular orbital connection to a portion of the base, a rear boom in circular orbital connection to another portion of the base, a seat platform supported by the actuator assembly, and a back platform supported by the actuator assembly. The seat platform and the back platform are capable of remaining stationary relative to the actuator assembly while the actuator assembly moves relative to the base. The seat platform and the back platform are also capable of moving relative to the actuator assembly while the actuator assembly remains stationary relative to the base. The seat platform and the back platform are also capable of moving relative to the actuator assembly while the actuator assembly moves relative to the base.

A tilt-swivel chair employing a bearing base assembly in communication with connection plate or seat plate of the chair is provided. The tilting mechanism in forward and backward direction is provided by the spring which has a pushing and pulling action and the swiveling action is done along the side axis of the bearing base assembly, and the side axis is a cylindrical shape section with a bushing cap onto which a lever base is equipped and is connected to the connection plate or seat plate. The balance ball feeling is provided with the spring action. A cam and lever mechanism is provided at the base of the side axis in corporation with the base section of the assembly. The cam and lever mechanism provides a smooth swiveling action to the seat and to lock and shut down and take a break.

A reclinable office chair includes a reclination adjustment unit disposed at the bottom of the office chair. The reclination adjustment unit balances itself on the floor properly, resiliently and steadily. The office chair tilted in a forward-backward direction and/or a left-right direction displays directional stability relative to the floor in a manner not to lose the directional stability even when a sitter tilts in any direction, thereby allowing the office chair to provide a comfortable seat for the sitter to sit on, regardless of whether the office chair is upright or tilted in any direction.