Abstract: A chair is provided which comprises a support, a seat arranged above the support, and a seat back tiltably connected to the support behind the seat. The seat back has an upper back supporting portion and a lower waist supporting portion. The chair further comprises a mechanism for deforming the waist supporting portion forward until the seat back tilts rearward to a predetermined intermediate tilt angle but for retarding or stopping such forward deformation when the seat back tilts rearward beyond this intermediate tilt angle. The seat may be made to move rearward as the seat back tilts rearward.

Abstract: The present invention provides a tilting control assembly for a chair. The chair comprises a support device, a seat supported above the support device, and a seat back arranged behind the seat to tilt rearwardly. The tilting control assembly comprises a tilting control spring device for elastically supporting the seat back against rearward tilting thereof via a load applying member, a displacing mechanism responsive to a downward load applied to the seat for causing the load applying member to move relative to the spring device, and a lock device for preventing the load applying member from moving reversely relative to the spring device when the seat back is rearwardly tilted.

Abstract: The present invention provides a chair tilting control assembly which comprises a fixed frame mounted on a chair leg post, a tiltable member supported by the fixed frame to tilt downward about a lateral support shaft, and a chair seat movable downward under the weight of a sitter. The tilting control assembly comprises at least one tilting control spring for elastically supporting the tiltable member at a certain support position relative thereto, and a motion converting mechanism which converts downward movement of the seat into displacement of the support position rearwardly away from the lateral support shaft.

Abstract: The present invention provides a tilting control assembly for a chair which comprises a support mechanism mounted on a chair leg post, a chair seat carried by the support mechanism, and a chair back arranged behind the seat. At least one of the seat and the back constitutes a tiltable member. The tilting control assembly comprises at least one tilting control spring for elastically supporting the tiltable member via at least one contact member, and an adjusting mechanism which is automatically responsive to the weight applied to the seat for causing relative displacement between the tilting control spring and the contact member in a manner such that the spring constant of the tilting control spring increases as the applied weight increases.