Patent ID: 7712833

Claim:
A structure for connecting members, comprising: a first member having stiffness; a second member movable relative to the first member and having stiffness; a spring member having a first end portion connected to a rear portion of the first member and a second end portion connected to a rear portion the second member so as to accumulate a reaction force by elastic deformation, a back frame comprising at least a pair of the lower frame elements on the right and left, at least a pair of the upper frame elements on the right and left, and at least a pair of the spring members on the right and left for connecting one of the lower frame elements to a corresponding one of the upper frame elements, wherein the spring member is formed into a frame shape extending along the first and second members, wherein at least a portion of the spring member is spaced from said first and second members, wherein the first member is a lower frame element constituting a backrest lower portion of a chair, wherein the second member is an upper frame element constituting a backrest upper portion of the chair, wherein each of the right and left upper frame elements are capable of tilting independently, and wherein a bottom end of each of the upper frame elements on the right and left is attached to a top end of a corresponding one of the lower frame elements on the right and left, such that each of the upper frame elements on the right and left is pivotable relative to a corresponding one of the lower frame elements on the right and left.