Mechanical timepiece with timed annular balance rotating angle control mechanism

Abstract

A mechanical time piece has a mainspring for generating a rotational force and a front train wheel for undergoing rotation in accordance with a rotational force generated by the mainspring. An escapement and speed control apparatus controls rotation of the front train wheel and has a timed annular balance for undergoing reciprocal rotational movement, an escape wheel and pinion for undergoing rotation in accordance with rotation of the front train wheel, and a pallet fork for controlling rotation of the escape wheel and pinion in accordance with rotational movement of the timed annular balance. A switch mechanism outputs an ON signal when a rotational angle of the timed annular balance becomes equal to or larger than a predetermined threshold angle and outputs an OFF signal when the rotational angle of the timed annular balance does not exceed the threshold angle. A balance rotational angle control mechanism applies a force to the timed annular balance to restrain rotation of the timed annular balance when the switch mechanism outputs the ON signal. The balance rotational angle control mechanism has a balance magnet disposed on the timed annular balance and a plurality of coils for exerting a magnetic force to the balance magnet to thereby restrain rotation of the timed annular balance when the switch mechanism outputs the ON signal and for not exerting a magnetic force to the balance magnet when the switch mechanism outputs the OFF signal.

Dependencies are inferred from the claim text.