Continually positionable chair with adjustable lumbar support

Claim 1

A continually positionable chair, positionable between a rear rest position and selected forward positions suited to a user's task, and with a backrest providing support to a user's lumbar region if said chair is positioned near said rear rest position, said chair comprising: a seat cushion having a base surface separated from a seating surface by a greater amount at locations toward its front facing end than at locations near its rear facing end; a support frame, attached to said seat cushion base surface, having a pair of legs extending away from said seat cushion base surface and supported by a pair of non-parallel, curved rails spaced further apart from one another toward rear portions thereof than they are toward front portions thereof, said rails extending forward sufficiently such that said chair can be tilted forward therealong on a horizontal surface until said seat cushion base surface slopes downward, and extending rearward sufficiently that said chair can be tilted rearward therealong until said seat cushion base surface again slopes downward; and a backrest having a backrest frame extending from said seat cushion base surface to curve upward, and having a backrest cushion with a back surface separated from a support surface thereof by a greater amount at locations near its upward facing end surface than at locations near its downward facing end surface, said backrest cushion being adjustably attached to said backrest frame such that said backrest cushion can be adjusted upwardly and downwardly along said backrest frame within a selected range so that it may be positioned to support a user's lumbar region.