US Patent 7695067 Ergonomic adjustable chair

A chair mechanism for an ergonomically adjustable, reclinable chair includes a frame and profile bands mounted to the frame. The profile bands are flexible and are configured to define a forwardly projecting lumbar region, the degree of forward projection of the lumbar region being variable in response to the position and movement of the chair seat. A flexible back support surface is carried by and spans the region between the profile bands. The shape and contour of the back surface is controlled by the shape of the profile bands. The chair mechanism enables the user to shift easily between upright and reclining positions without requiring the use of heavy springs or complex linkages.