Back support structure

Abstract

A tiltable chair including a base, a fulcrum member having a curved support surface, a back support pivotally connected to the base at a pivot axis and pivotable between at least an upright position and a rearward tilt position, and at least one leaf spring having first and second ends, with the first end being restrained by the base. The at least one leaf spring engages the curved support surface of the fulcrum member at a first contact point when the back support is in the upright position and at a second contact point when the back support is in the rearward tilt position, wherein the second contact point is positioned rearwardly on the at least one leaf spring relative to the first contact point. A link member is pivotally connected to the back support at a first pivot location and is pivotally connected to the at least one leaf spring at a second pivot location. The link member defines a vector between the first and second pivot locations and the first pivot location and the pivot axis define a plane. The vector and the plane define a first angle when the back support is in the upright position and a second angle when the back support is in the rearward tilt position, wherein the second angle is closer to ninety degrees than the first angle. A method of using a chair is also provided.

Dependencies are inferred from the claim text.