Back support and internal frame

Claim 1

A frame for a back support, said back support being adapted to face forwardly towards a user's back, said frame comprising; (a) an elongated center portion having a top and a bottom and a pair of sides and extending in a longitudinal direction between said top and bottom, said center portion also extending in a transverse direction between said sides, said transverse direction being at right angles to said longitudinal direction, said center portion being configured in one of a substantially flat orientation and a slightly convex forward orientation. (b) a pair of wing portions, said wing portions extending oppositely in said transverse direction and forwardly, one wing portion extending from each side of said center portion, said wing portions having outer free ends, (c) said wing portions being of smaller dimension in said longitudinal direction than said center portion and being located adjacent said bottom of said center portion, there being no wing portions adjacent the top of said center portion, (d) said center portion comprising a plurality of parallel column supports spaced apart in said transverse direction and extending in said longitudinal direction, there being a pair of said column supports one adjacent each side of said center portion, and a plurality of column supports between said pair of column supports, (e) said center portion further including a plurality of cross members extending in said transverse direction and each connected rigidly to each of said column supports, (f) at least one of said cross members having a pair of wing sections extending transversely into said wing portions, said one cross member being located in a lumbar region of said user's back, for said wing sections to be depressed rearwardly when a user sits against said backrest and for the rearward movement of said wing sections to cause said center portion to bulge forwardly at least adjacent said one cross member and hence to assume a convex shape adjacent said lumbar region, and for said center portion to remain unbulged forwardly adjacent its top, so that the center part of said center portion will then assume an increasingly convex shape from said top of said center portion to said one cross member, such convexity providing lumbar support to said user.