Patent ID: 7156457

Claim:
A seat structure, comprising: an arm arranged in the rear of a seat cushion and held in a torsionally flexible position by a torsion bar having a torque toward the rear of said seat structure; a supporting frame supported by said arm and arranged along the rear of the seat cushion; a pair of parallel side frames extending along the sides of said seat cushion; a front frame arranged in the front of the seat cushion, having a predetermined width in a longitudinal direction of the seat cushion, and movably coupled to said side frames such that the front edge of said front frame is angled in a vertical direction; a first cushioning member spread over said supporting frame and said front frame, and held taut by the torque of the torsion bar; and a standard position setting member coupled to either or both of said side frames, structured and arranged to set a standard position by limiting the upward movement of the front edge of said front frame when a person is seated on said first cushioning member in a standard posture, and wherein the standard position setting member is structured and arranged not to limit the upward movement of the front edge of said front frame when any portion of said first cushioning member is depressed with a force that is substantially greater than the force applied to the first cushioning member when a person is seated on said first cushioning member in a standard posture, and a haunch supporting portion of said first cushioning member is lifted upward by forcing the front edge of said front frame downward below the standard position.