A chair for providing support to a user's spine to improve posture and for providing ways for the user to perform exercises. The chair may include a flexible connection that enables a back support to move side to side through a sidebending range of motion of the user. The back support, which may include a flexible chair spine, may be configured to adapt to the curvature of the user's spine when the user is seated in the chair. A seat of the chair may include channels and vents to improve air circulation within the seat.

A pivot shaft (10) which is a first shaft member coupled to a supporting member, an inner cylinder (12) which is a second shaft member coupled to a supported member, and an outer cylinder (14) which is a third shaft member are disposed to be approximately coaxial with each other and disposed radially in multiple layers. The pivot shaft (10) and the inner cylinder (12) are coupled to each other through a first rubber-like elastic member (11), and the inner cylinder (12) and the outer cylinder (14) are coupled to each other through a second rubber-like elastic member (13). The total reaction force is increased by restricting the rotation of the outer cylinder (14) by means of an operating pin (19) which is a reaction force adjusting part and thereby adding a reaction force resulting from the second rubber-like elastic member (13) to a base reaction force resulting from the first rubber-like elastic member (11).

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.

The flexible support device is used for chair back tilting, which is installed under a cushion. The device includes a base, two driving members connected to the chair back, a pulling rod crossing the base and a spring disposed in the base. The base is connected to ends of the driving members. Two ends of the pulling rod are separately connected to two free ends of the two driving members. The pulling rod has a frame encompassing the spring. The frame has an action end blocking the spring. When the chair back is pressed to tilt rearward, the driving members are rotated to draw the pulling rod to move toward the chair back, and the action end of the frame is driven to compress the spring so as to make the chair back flexibly supported.

An oscillation mechanism for chairs includes a support frame, a structure coupled to the support frame to rotate about a first axis, an elastic element interposed between the support frame and the structure and configured to oppose a reaction force to an oscillation of the structure. The reaction force generates a reaction moment acting on the structure with respect to the first axis. An oscillation adjustment system is able to vary the reaction moment with the oscillation being unchanged. The adjustment system includes a pin movably coupled to the structure and a movement system of the pin for varying the distance between the pin and the first axis. The elastic element is directly fastened to the pin so that the reaction force is transmitted to the structure with the application point corresponding to the pin and with direction and orientation unchanged.

A seat assembly includes a frame made from a first material having a first hardness, the frame including a first side and a second side opposite the first side. The seat assembly further includes a fabric component coupled to the first side of the frame, and a plurality of grooves are disposed within the second side of the frame. Each insert of a plurality of inserts are disposed within each respective groove in the plurality of grooves. Each insert of the plurality of inserts comprises a second material and the second material has a second hardness that is less than the first hardness.

A resistive motion support mechanism joined to a mounting surface and to a base for providing resistive support to the mounting surface as the mounting surface undergoes one or both of rotational and tilt movement relative to the base, the motion support mechanism comprising: a support bearing connected to the mounting surface and to the base which permits one or both of tilting and rotational motion of the mounting surface relative to the base; a resistance cartridge fixedly connected to the mounting surface such that the resistance cartridge undergoes movement relative to the base and applies a resistive force on the base as the mounting surface undergoes the one or both of rotational and tilt movement. The mounting surface and the resistance cartridge are connected by at least one sensor for measuring one of forces applied by the mounting surface on the resistance cartridge, movement of the mounting surface with respect to the cartridge and/or acceleration of the mounting surface with respect to the cartridge.

A chair assembly includes a back support arrangement including a back support arrangement, a seat support arrangement and a four-bar arrangement that includes a rearward end and a forward end that is adjustable between a raised and lowered positions, and an arm rest assembly adapted to support the arm of a seated user thereon and supported on the forward end of the four-bar arrangement, wherein the rearward end of the four-bar arrangement is pivotably supported from an arm support structure for pivotable movement about a substantially vertical pivot axis such that the forward end of the four-bar arrangement is moveable between a first position and second position located laterally outward from the first position, and wherein the substantially vertical pivot axis is located forwardly of a rearmost edge of an upwardly-facing surface of the seat support arrangement.

A chair control assembly includes a base structure having first and second pivot points spaced from one another, a seat support structure coupled to the first pivot point, a back support structure coupled to the second pivot point and adapted to move between first and second positions, wherein the base structure does not move as the back support structure moves between the first and second positions, and a control link pivotably coupled to the seat support structure for rotation about a third pivot point and pivotably coupled to the back support structure for rotation about a fourth pivot point, wherein the third pivot point is rearward of the fourth pivot point when the back support structure is in the upright position, and the third pivot point moves forward relative to the fourth pivot point as the back support structure moves from the upright to reclined positions.

The invention relates to a chair (1) which comprises a support (6), a seat element (5), a back element (4), a leg element (3), a spring mechanism and a weight-controlled working adjusting element for the spring mechanism.