Abstract: A chair with a back-and-forth moving backrest comprises a seat and a backrest, the lower end of the backrest is separated from the seat; both sides of the lower end of the backrest are respectively connected with both sides of the back end of the seat by a rotating mechanism; the lower end of the rotating mechanism can be rotatably regulated relatively to the seat; the upper end of the rotating mechanism can be rotatably regulated relatively to the backrest; during the rotating regulation of the rotating mechanism, the backrest only moves back and forth relatively to the seat without changing the vertical state of the backrest.

Abstract: A chair with a back-and-forth moving backrest comprises a seat and a backrest, the lower end of the backrest is separated from the seat; both sides of the lower end of the backrest are respectively connected with both sides of the back end of the seat by a rotating mechanism; the lower end of the rotating mechanism can be rotatably regulated relatively to the seat; the upper end of the rotating mechanism can be rotatably regulated relatively to the backrest; during the rotating regulation of the rotating mechanism, the backrest only moves back and forth relatively to the seat without changing the vertical state of the backrest.

Abstract: An self adjusting back support assembly for a seat is provided comprising a plurality of pivotally adjustable back support members juxtaposed one another such that each of said back support members is able to pivot about an axis contained wholly within an adjacent back support member allowing the back support assembly to adopt a serpentine contour substantially following a contour of an occupant's back.