Hand held ultrasonic nebulizer
AssigneeChampion Spark Plug Company
InventorsRaymond L. Abair, Stanley J. Kulish, Jr.
Life of this patent
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Abstract
An improved ultrasonic nebulizer for administering a medicament aerosol to a patient. Output from an oscillator is connected through a series inductor to a transducer adjacent a reservoir which generates aerosol from the medicament. The inductor is tuned for series resonance with the bulk capacitance of the transducer. An impedance change in the transducer when liquid is removed or consumed from the reservoir reduces the power delivered to the transducer and prevents transducer damage.
Claims7
An ultrasonic nebulizer comprising, in combination, means defining a liquid reservoir, transducer means for atomizing liquid in the reservoir, said transducer means functioning essentially as a bulk capacitance in parallel with a series resonant circuit when excited within a predetermined frequency range of resonance, said series resonant circuit when excited within such frequency range having a predetermined high resistance when liquid is present in said reservoir and a predetermined lower resistance when mechanically unloaded by the absence of liquid from said reservoir, an oscillator having an output within such frequency range, and means coupling said oscillator output to said transducer means including an inductor, said inductor cooperating with said bulk capacitance and any stray capacitance in circuit with said bulk capacitance to form a series resonant circuit resonating within such frequency range whereby, when liquid is removed from said reservoir, said predetermined low resistance reduces the voltage across said bulk capacitance to in turn reduce power dissipated in such mechanically unloaded transducer means.
In an ultrasonic device having a piezoelectric transducer which, when excited within a predetermined frequency range of the transducer resonant frequency, functions essentially as a bulk capacitance in parallel with a series resonant circuit with said series resonant circuit having a predetermined high resistance when said transducer is mechanically loaded and a predetermined lower resistance when said transducer is mechanically unloaded, an improved protective circuit for exciting said transducer comprising, in combination, means for generating an alternating current signal within such predetermined frequency range, and means coupling such alternating current signal to said transducer including an inductor, said inductor, said transducer bulk capacitance and any stray capacitance in circuit with said bulk capacitance resonating within such frequency range whereby, when said transducer is mechanically unloaded, said predetermined low resistance reduces the voltage across the bulk capacitance to in turn reduce power dissipated in such mechanically unloaded transducer.
In an ultrasonic device having a piezoelectric transducer which, when excited within a predetermined frequency range of the transducer resonant frequency, has a first impedance when mechanically loaded and a signficantly different second impedance when mechanically unloaded, an improved protective circuit for exciting said transducer comprising, in combination, means for continuously generating an alternating current signal within such predetermined frequency range, and means coupling such alternating current signal to said transducer, said generating means and said coupling means including means for delivering a normal operating power to said transducer when said transducer has such first impedance and for delivering a substantially reduced power to said transducer when said transducer has such second impedance whereby said transducer is protected from damage when mechanically unloaded.
Dependencies are inferred from the claim text.