| 摘要 |
PROBLEM TO BE SOLVED: To prevent an electromagnetic vibration actuator used for an arriving call of a portable telephone or other applications, generating various vibrations and not affected by the voltage fluctuation of a power source. SOLUTION: Two electromagnets 3 and 5 formed to a U shape are mounted into a case 2 in the form that two virtual lines connecting their respective both ends intersect with each other. A columnar moving element 7 is freely oscillatably supported at the case by means of an elastic shaft 6 at the intersection point of these virtual lines. A power source to supply electric power to the electromagnets 3 and 5 is disposed and the magnetic poles (N pole and S pressure) of the respective electromagnets 3 and 5 are switched in accordance with the prescribed input information. As a result, the moving element 7 is made to make various elastic motions (longitudinal vibrations in transverse direction, oscillations and circular motions in a diagonal direction). The voltage fluctuation of the power source is detected and the pulse number or pulse width of the drive pulses is increased or reduced according to voltage fluctuation to maintain the specified magnetic force of the electromagnets 3 and 5. As a result, the magnetic forces of the electromagnets 3 and 5 do not change any more even if the voltage rises or falls.
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