Patent ID: 6422739
Filing Date: 2002-07-23
Classification: G04B

Abstract:
A mainspring device that drives a primary wheel train by mechanical energy of a mainspring, comprising:a winding-up portion that accumulates energy in said mainspring; an addition-and-subtraction wheel train driven by addition and subtraction of accumulated energy corresponding to an amount by which the mainspring is wound up and unwound, respectively; an addition-and-subtraction wheel, disposed in said addition-and-subtraction wheel train, that rotates in correspondence with an amount by which said mainspring is wound up and unwound, said addition-and-subtraction wheel having a single plane of rotation; and a lock mechanism actuated in response to the rotation of said addition-and-subtraction wheel to limit winding up and unwinding of said mainspring to a selected range of windings, and to thereby prevent transmission of torque having a value outside a set range from said mainspring to said primary wheel train.