US Patent 7216933 Backrest, particularly for an office chair

In the case of a backrest (1), in particular for an office chair, having a lordosis support (3) comprising supporting ribs (2) arranged in a manner such that they run parallel to one another, said supporting ribs are precurved in a flexurally elastic manner in their starting position. An adjusting element (9), which can be actuated via an adjusting member (6) and is intended for setting the lordosis curvature (18), is guided on the curvature side (12) of the lordosis support (3) in such a manner that the lordosis curvature (18) decreases during a tensile loading of the adjusting element (9).