Balance joint (1, 101) suitable for attachment between a seat arrangement (6, 106) and a chair leg arrangement (7, 107). The balance joint comprises first and second mountings (2, 3, 102, 103) together forming a hollow space and at least one hinge pin (4, 104). The mountings (2, 3, 12, 103) are rotatably attached to each other by means of the at least one hinge pin, where at least one elastic packing (5, 105) is arranged in the hollow space and the at least one elastic packing is arranged between the mountings so that the possibilities for expansion of the elastic packing is limited by the mountings (2, 3, 102, 103) in at least two directions. It is also described various furniture using such a balance joint.

A topple-proof buffering structure for the chair comprises an elastic supporting plate having two deforming buffering portions protruded from an outer side of a fixing substrate, a seat fixing plate assembled to a bottom side of a seat of the chair, and at least two flexible pillars respectively having a bolt member, a screw hole member, and a limit screw. The bolt member has an embedding end and an outer threading section. An inner screw hole is arranged at a surface of the embedding end. One end of the screw hole member opposite to the screw hole has a small diameter hole and a retaining lip. The limit screw is passed through the small diameter hole of the screw hole member and screwed in the inner screw hole of the bolt member so as to support the flexible pillars not to be damaged and broken.

A back support cushion device includes a support member, at least one cushion assembly, and at least one elastic assembly. The support member includes a first groove. The cushion assembly includes a second groove. The elastic assembly is located between the support member and the cushion assembly and includes an elastic member, and first and second members. The elastic member includes first and second portions. The first portion is engaged into the first groove, and the second portion is engaged into the second groove. The first member includes a first end disposed in the first portion and a second end connected to the first groove. The second member includes a first end disposed in the second portion and a second end connected to the second groove.

A chair system according to embodiments of the present invention includes a base comprising a seat for a user and one or more support legs, a back, and a flexible back support element rigidly coupled to the back and to the base, the flexible back support element comprising a flex zone, the flex zone comprising one or more notches, wherein the back is reclinable from an upright position to a reclined position, wherein the one or more notches are configured to narrow as the back reclines from the upright position to the reclined position, and wherein the one or more notches are open in the upright position and closed in the reclined position.

A back support cushion device includes a support member, at least one cushion assembly, and at least one elastic assembly. The support member includes a first groove. The cushion assembly includes a second groove. The elastic assembly is located between the support member and the cushion assembly and includes an elastic member, and first and second members. The elastic member includes first and second portions. The first portion is engaged into the first groove, and the second portion is engaged into the second groove. The first member includes a first end disposed in the first portion and a second end connected to the first groove. The second member includes a first end disposed in the second portion and a second end connected to the second groove.

A chair for providing seating support to a user and for providing ways for the user to perform exercises. The chair includes a back support that is flexible such that when a force is applied to it by the user's body, the back support bends. The back support may be configured to adapt to the curvature of the user's spine when the user is seated in the chair. The back support may further be configured such that the user can rotate the back support by rotating the user's upper body.

An adjustable chair can support an occupant that sits on a front portion of a seat cushion. When the user leans back, the chair can provide back support without requiring that the user slide rearwardly along the seat cushion, thereby providing back support to minimize, limit, or substantially eliminate lower back fatigue, discomfort, or the like. A back support of the chair can be located at a desired forward/rearward position based on the user's position on the seat. In some settings, the chair can be used by a card dealer who tends to sit on a forward portion of the seat when dealing cards. The back support can be positioned to comfortably support the dealer's back when, for example, the dealer sits generally upright. The chair can also be used by other individuals that frequently sit on the front of the seat cushion.

A piece of furniture comprises a seat, a backrest and a base. At least the seat and the base are movably coupled for reversible relative adjustment in a direction from a first configuration for sitting upright to a second configuration for sitting reclined. One or more support surfaces and a lever are operably coupled to support the seat on the base. The lever rotates about an axis transverse to the seating direction and moves being coupled with the one or more support surfaces at a first support portion defining first lever arm about the axis and a second, different, support portion defining a second, different, lever arm about the axis. The one or more support surfaces define a curved, noncircular path about the axis, such that relative displacement of the support surface and the axis in the seating direction is associated with rotation of the lever about the axis.

A swivel chair that includes a base, a rigid component, elastic components, and a chair seat. The base is provided with a rotating shaft that is located at a center and capable of rotating relatively. A middle rear part of the rigid component is connected to the rotating shaft. Front ends of the elastic components are connected to a front end of the rigid component. The chair seat includes a seat plate and a connecting piece connected to a middle rear area of a bottom of the seat plate. A bottom of the connecting piece is connected to rear ends of the elastic components. After elastic deformation is produced under the driving of the chair seat, the rear ends of the elastic components can be subjected to a pressure and integrally backward incline to a certain degree together with the chair seat, and can also forward incline slightly.