A home or office chair is disclosed having a flexible mesh back rest and a full lumbar back support including upper and lower lumbar supports that are located one above the other at the back of the chair to press against the outside of the mesh back rest. The upper and lower lumbar supports are connected to the back of the chair by a bolt so as to move back and forth in first and opposite directions in response to a user seated in the chair moving his back against and away from the flexible mesh back rest. The upper and lower lumbar supports of the full lumbar back support apply continuous pressure through the mesh back rest to provide support for upper and lower lumbar areas of the user's back regardless of whether the user's back is at rest or pressing against the mesh back rest.

A chair includes, a seat, a backrest separated from the seat, and an upper support frame to which the backrest is attached at a position higher than the seat. In the chair, the upper support frame includes a left side portin and a right side portions both extending forward at left and right sides of the seated person and a rear portion that continuously and integrally connects the left side portion and the right side portion. The left side portion and the right side portion are connected to side support bodies arranged on left and right sides of the seat to be tiltable, and the backrest is connected to the upper support frame to be tiltable rearward.

To realize a noble, useful seat with a simple structure designed to follow a natural movement of a seated person in front-rear and left-right directions and to support appropriately a movement of the person continuously changing its posture while the person balances a load. The seat includes the elastic support layer 3 and upper and lower base units 4 and 5 arranged to sandwich the elastic support layer 3. The upper base unit 4 includes the rolling surface 42e bulging toward the lower base unit 5 thereabove via the elastic support layer 3, is rollable in a 360° direction from the tilt reference position IRP in receiving a load of the seated person, and has a moving distal end side tilting more downward as a distance from the position IRP increases, and is configured to move while compressing the elastic support layer 3 by the rolling surface.

A chair can include a base having at least one chair back attachment mechanisms that attach a back of the chair to the base of the chair. The chair back attachment mechanisms can be positioned on an upper portion of the frame of the base of the chair to support the chair back. In some embodiments, there may be a single chair back attachment mechanism or only a pair of chair back attachment mechanisms to attach the chair back to the base. The chair back can be positioned via the chair back attachment mechanisms so that there is a gap between the lower portion of the chair back and the seat. Embodiments of the chair can be armless. Other embodiments can include arms positioned above the seat on opposite sides of the seat to support arms of a user sitting on the seat of the chair.

A home or office chair is disclosed having a flexible mesh back rest and a full lumbar back support including upper and lower lumbar supports that are located one above the other at the back of the chair to press against the outside of the mesh back rest. The upper and lower lumbar supports are connected to the back of the chair by a bolt so as to move back and forth in first and opposite directions in response to a user seated in the chair moving his back against and away from the flexible mesh back rest. The upper and lower lumbar supports of the full lumbar back support apply continuous pressure through the mesh back rest to provide support for upper and lower lumbar areas of the user's back regardless of whether the user's back is at rest or pressing against the mesh back rest.

A swingable chair chassis comprises a rocker seat including a chamber defined between a bottom wall and a peripheral wall. The bottom wall includes a slot extending in a front/rear direction. A lid is securely mounted to a bottom of the seat and the rocker seat. A supporting seat is disposed in the chamber of the rocker seat. The supporting seat includes a central portion having an insertion hole coupled with chair post. The supporting seat includes an arcuate supporting face formed on an upper side thereof and abutting against a lower face of the lid. A plurality of elastic elements is disposed between the bottom wall of the rocker seat and the supporting seat and provides movement elasticity when the rocker seat swings forward or rearward relative to the supporting seat. The supporting face abuts against the lower face of the lid during swinging movement of the rocker seat.

A chair having an articulating backrest that deforms when reclined to support an occupant's head or shoulders. A backrest assembly includes a mesh insert secured to a frame, which includes an upper frame section and a lower frame section interconnected by a pair of articulated joints. A push arm pivotally connects to the chair's seat assembly and to the backrest's upper frame section. As the chair reclines, the push arm restricts the angular movement of the upper frame section relative to a floor. The lower frame section moves forward relative to the upper frame section. Consequently, an angle formed between the lower frame section and the upper frame section decreases during recline, thereby supporting the chair occupant's head or shoulders. Optionally, a tensioning member may connect the mesh insert to the push arm to offset any loss of tension caused by the deformation of the frame during reclined.

A mechanism for an office chair is structurally particularly simple and consequently comparatively inexpensive, but nevertheless extremely variable. Both the seat support and the backrest support are articulated by way of a common pivot axis. The seat support is connected in an articulated manner to the base support by way of at least one pivot bolt and is pivotable relative to the base support. The backrest support is connected in an articulated manner to the base support by way of the at least one pivot bolt and is pivotable relative to the base support.

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 seating structure employing a thermoplastic flexor defining the flexibility and stiffness of a seatback is provided. The seating structure may comprise a seat portion for supporting a user, a seatback portion for supporting a user, a frame for supporting the seat portion and the seatback portion, one or more base portions extending at an angle from the seatback portion, and one or more thermoplastic flexors affixed to or within the seatback and base portions of the seating structure. The thermoplastic flexor has certain material characteristics which define and limit the deflection and a rebound of the seatback portion relative to the base portion when under load. The seating structure may further comprise one or more anchors securing the seatback portion, base portion, and thermoplastic flexor to the frame. The seat portion, seatback portion, and base portion may comprise a unibody or multipiece chair shell, and the thermoplastic flexor may be completely enveloped within the shell, or partially disposed behind the shell in a nested mechanical relationship.