| 摘要 |
The present invention relates to a nebulizer comprising an electrically energizable ultrasonic transducer having an oscillation frequency dependent current and voltage characteristic exhibiting the occurrence of a minimum magnitude of current through the transducer at an anti-resonance frequency of the transducer, the voltage across the transducer increasing with an increase in frequency within a range of frequencies including said anti-resonance frequency. The nebulizer further comprises a transducer drive system for generating a drive signal for energising the transducer, the drive system comprising oscillation frequency control means operable to maintain the frequency of the drive signal at a specific frequency within said range of frequencies by reference to the variation of both current through the transducer and voltage across the transducer with a change of frequency within the said frequency range. The transducer is arranged to receive said drive signal and to cause physical vibrations in fluid to be nebulized when energised by said drive signal. A transducer having a simple automatic frequency tuning system is thereby provided.
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