| 摘要 |
The drive method consists in setting in vibration a moving mass of a vibrating device for a portable object using a series of voltage pulses provided to the coil of the vibrating device, which is electro-magnetically coupled to the moving mass. In a phase of driving the oscillations of the moving mass after a start phase of the vibrating device, followed by a resonant frequency measurement phase, successive rectangular voltage pulses of alternating polarity are provided to the coil by a drive circuit. The width of the successive pulses is modulated in a substantially similar manner during each successive oscillation period which allows a substantially sinusoidal voltage wave (S<SUB>F</SUB>) of determined amplitude to be defined whose fundamental frequency is adapted to the resonant frequency of the moving mass. By modifying the oscillation period, it is thus possible to act on the amplitude of the moving mass oscillations which depends on the sinusoidal wave amplitude defined by the rectangular pulse width modulation.
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