Torque converting mechanism for use in e.g. perpetual calendar mechanism in timepiece, has lever with bearing surface that includes shape formed in manner such that length of lever arm is reduced for compensating increase in return force

摘要

The mechanism has a return spring (3) and a lever (1) fixed on a frame (6). The lever comprises a bearing surface (1-2) against which a free end (3-1) of the spring is acted directly or indirectly. The bearing surface has shape formed in a manner such that length of a lever arm (L2) is reduced for compensating increase in return force supplied by the spring by considering a relative position of the spring and a pivoting point (A) of the lever.