A rebounding device includes a front member, a rear member, and a spring mechanism including a first biasing element and force adjustment assembly. The force adjustment assembly includes a spring element including a front planar surface and a rear planar surface connected at a rounded portion, wherein the front planar surface contacts an inner surface of the front member; a screw housing secured to an inner surface of the rear member, wherein the screw housing includes a longitudinal channel and a bore on an upper surface; a drive screw positioned through the bore and along the longitudinal channel of the screw housing; a threaded block positioned within the longitudinal channel of the screw housing, wherein the threaded block is configured to move vertically along the longitudinal channel, and wherein the rear planar surface of the spring element is secured to the threaded block.

The invention relates to a seat device (1) comprising an underframe (2) and a seat (3) connected to the underframe (2) in such a way as to pivot about a seat axis (A1), there being provided means for elastically biasing the seat (3) in anti-clockwise rotation. The seat device (1) further comprises a lumbar part (42); rotationally secured to the seat (3), and a saddle (5) for supporting the top of the thighs of the user, the saddle (5) being connected to the front region of the seat (3).

A pivoting mechanism with a first member, a second member pivotally engaged with the first member to pivot about a pivot axis, and pivoting resistance mechanism with a spring housing disposed in the first member spaced from the pivot axis, a spring disposed in the spring housing, and a deflecting member that projects from the second member spaced from the pivot axis to engage the spring disposed in the spring housing. The first member can be a chair mechanism body, and the second member can be a pivoting support, such as for a chair bottom or back. A height adjustment mechanism has a movable member, and a locking member, such as a screw, can be operative as a height locking mechanism with a first, restraining condition wherein actuation of the movable member is prevented and a second, non-restraining condition wherein actuation of the movable member is permitted.

A reconfigurable apparatus for sitting and having a seat mounted on a frame and movable under the weight of a sitting user. As an incident of the user sitting, resistance to movement of a back rest component is increased a predetermined amount based upon the user's weight. A manually operable subassembly allows the increased resistance to be changed from the predetermined amount with the user sitting on the seat.

A chair according to the present invention has a reference position P located midway in a front-back direction in a movable range of a seat 2. The chair includes a return force generation mechanism 4 configured to generate a return force in a direction to return the seat 2 moved from the reference position P at least in the front-back direction to the reference position P. The return force generation mechanism 4 includes an elastic member 40 configured to increase the return force in the direction to return the seat to the reference position P as the amount of movement of the seat from the reference position P increases.

To provide a chair in which the seated person can perceive a comfortable sitting feeling even if sitting for a long time, and furthermore a high work efficiency can stably be maintained, a chair according to the present invention includes a support mechanism 2 interposed between a leg 1 and a seat 3, wherein the support mechanism 2 includes: a seat inclining mechanism Q as a seat inclining function configured to downwardly incline a tip side in an operation direction of the seat 3 when the seat 3 operates from a predetermined reference position (S), and further includes: a return-force generation mechanism configured to generate, in accordance with an amount of movement, a return force in a direction of returning the seat 3 having moved from a reference position (S) in a front-rear or left-right direction, to the reference position (S).

A resilient backrest dampening mechanism is provided for use with chairs having a seat and a backrest, the mechanism comprising four pivot points; a first pivot point arranged on a base different from the backrest; a second pivot point arranged at a distance from the first pivot point on the base, wherein a bracket is pivotally connected to the second pivot point; a third pivot point provided between the bracket and a first end of a backrest connection member, and the backrest connection member being adjustably connected to the backrest; a fourth pivot point provided in the bracket; a resilient member arranged between the fourth pivot point and the first pivot point, and wherein all the pivot points pivot around corresponding axes and all of the axes are parallel.

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.

A reconfigurable apparatus for seating a user and having: a frame; a seat movable relative to the frame between: a) a first position in which the seat resides with no user sitting on the seat; and b) a loaded position; a back rest with a changeable angular orientation relative to the frame; and an adjusting assembly having a plurality of gears that move relative to each other as an incident of the seat moving from the first position into the loaded position to thereby cause an increase in resistance to changing of the angular orientation of the back rest.

A chair, comprising, a backrest, a seat coupled with the backrest, a column coupled with the seat, a linkage statically attached to the backrest and rotatably attached below the seat, a leaf spring statically attached at one end and in direct contact with the linkage to provide a resistance to tilting of the backrest relative to the column, a first structure fixed to the column. A portion of the first structure has an arc shape that includes one or more teeth, and a second structure in contact with the first structure. The chair is configured such that, when a weight is applied to the seat, one or more teeth of the second structure move along the one or more teeth of the first structure to shorten a working length of the leaf spring and provide an increased resistance to tilting of the backrest relative to the column.