Importance

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Abstract

A mechanical watch includes a balance, an oscillation circuit configured to output a clock signal, a vibration detection unit configured to detect a vibration of the balance and output a vibration detection signal, a speed governing unit including a permanent magnet and a coil, a speed governing control unit, a storage unit configured to store an electrical energy, and a generator. One of the permanent magnet and the coil is held by the balance. The speed governing control unit compares the clock signal and the vibration detection signal and performs the speed governing control of the balance by exerting an electromagnetic force on the permanent magnet, the electromagnetic force being generated by outputting a current to the coil. When a stored energy amount is equal to or smaller than a predetermined value, the speed governing control unit switches a state to a stop state where the speed governing control of the balance is stopped.

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First Claim