Calendar mechanism

摘要

The mechanism has a calendar wheel driven in a first direction during normal operation of a timepiece. An actuating lever actuates a date star (22). Two cams are driven by the wheel and control movements of the lever such that relative angular position differs depending on direction of rotation of the wheel and movements of the lever cause the mobile to advance periodically during normal operation of the timepiece without permitting the mobile to advance during backwards time setting of the timepiece causing the wheel to rotate in a second direction opposite to the first direction.