Patent ID: 7566097

Claim:
A chair, comprising: a synchronous mechanism having a weight-adjusting mechanism to which a return force is applied in dependence on a current weight load, said weight-adjusting mechanism having a lever and the return force is applied by said lever, an effective lever arm length of said lever is changed for adjusting the return force, said weight-adjusting mechanism automatically adjusting the effective lever arm length for the current weight load; said synchronous mechanism having a position-adjustable pivoting element; said lever having a fixed lever fulcrum, the effective lever arm length being defined by a distance between said fixed lever fulcrum and said pivoting element; said synchronous mechanism further having a joint, a seat support and a backrest support connected to said seat support by said joint, said seat support and said backrest support being movably mounted in a common guide such that a distance between said pivoting element and said fixed lever fulcrum is adjusted depending on the current weight load; and wherein said pivoting element is disposed on said backrest support such that, when said synchronous mechanism is actuated, said pivoting element pushes said lever away, counter to the return force.