Patent ID: 7862120

Claim:
A chair, comprising: a backrest including a backrest surface, a plurality of frame elements, each including a lower frame element and an upper frame element with a hinge disposed therebetween, said plurality of frame elements being spaced with each other in a width direction, and a plurality of reaction force frame elements, each of said plurality of reaction force frame elements being formed in an approximately L-shape in a side view and having a first end connected to a back surface of one of said plurality of upper frame elements and a second end connected to a downward surface of one of said plurality of lower frame elements, wherein each of said upper frame elements is supported with the hinge at a lower end thereof, and is independently movable backward and forward, wherein a distance between upper ends of each of said upper frame elements increases when a first one of said upper frame elements is moved backward with respect to a second one of said upper frame elements, wherein each of said upper frame elements supports an upper portion of said backrest surface and each of said lower frame elements supports a lower portion of said backrest surface, wherein each of said upper frame elements are individually displaceable in a backward and forward direction without displacing a corresponding one of said lower frame elements, and wherein when said upper frame element tilts backwards around said hinge, a reaction force is accumulated based on an elastic deformation of the reaction force frame elements.