Surgery – Liquid medicament atomizer or sprayer – Ultrasonic
Reexamination Certificate
1994-10-04
2003-11-25
Lewis, Aaron J. (Department: 3761)
Surgery
Liquid medicament atomizer or sprayer
Ultrasonic
C128S200180
Reexamination Certificate
active
06651650
ABSTRACT:
TECHNICAL FIELD
This invention relates to an ultrasonic atomizer for pumping up a liquid from a liquid vessel by an ultrasonic pump and atomizing the liquid by passing it through a mesh plate formed to have multiplicity of minute holes, an ultrasonic inhaler serving as one application of the ultrasonic atomizer, and a method of controlling the operation of the inhaler.
BACKGROUND ART
A known example of an ultrasonic atomizer of this type is described in the specification of Japanese Utility Model Application Laid-Open No. 3-15674. The atomizer described in this literature is characterized by use of a mesh plate having tapered minute holes which flare from one side of the plate toward the other. The mesh plate is arranged in such a manner that the side in which the minute holes have the openings of larger diameter opposes the upper end face of the pump shaft of an ultrasonic pump, and such that a minute gap is produced between the mesh plate and the upper end face of the pump shaft.
In an ultrasonic atomizer, it is important to achieve balance between the amount of liquid pumped by the ultrasonic pump and the amount of atomization produced by the mesh plate. When there is a minute gap between the upper end face of the pump shaft and the mesh plate, as in the document mentioned above, the amount of liquid pumped tends to be larger than the amount of liquid atomized. The liquid that is not atomized flows down from the gap to the upper portion (the horn) of the pump shaft and becomes a load on ultrasonic vibration at the horn. This causes an unstable spraying operation and can lead to cessation of operation in some cases.
Another problem is that the user's fingers become soiled when liquid that has not been atomized flows out of the device. An important technical problem is assuring the liquid tightness of the device.
The number of minute holes formed in the mesh plate has a direct influence upon the amount of atomization. The greater the number of minute holes per unit surface area, the greater the amount of atomization. When the number of minute holes is increased, however, there is a decline in the strength of the mesh plate itself. There is a need for some expedient which can provide strength while allowing an increase in the number of minute holes.
Since the mesh plate described in the above-mentioned document is such that the minute holes have aperture diameters that differ on the two sides of the plate, care must be taken in terms of the orientation of these sides when the mesh plate is mounted in the atomizer.
An ultrasonic atomizer can be applied to an ultrasonic inhaler, as set forth above. Medicines of higher cost than inexpensive water and physiologic saline solutions are often used in inhalers. Accordingly, arranging it so that every drop of the medicine is used once the inhaler has been filled is important in terms of economy.
Another requirement of an inhaler is that the user repeat the operation for spraying the inhalant and halt this operation in conformity with breathing. Control of the spraying operation is achieved by having the user turn an operating switch on and off. However, turning the operating switch on and off often is troublesome or difficult particularly for the elderly or children. There is a need to arrange it so that the liquid is sprayed automatically and intermittently in conformity with the user's breathing.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a structure in an ultrasonic atomizer which makes it possible to achieve balance between amount of liquid pumped and amount of liquid atomized so that efficient and stable atomization can be obtained.
Another object of the present invention is to facilitate cleaning and replacement of the mesh plate.
A further object of the present invention is to provide a mesh plate having sufficient strength.
Yet another object of the present invention is to increase the amount of atomization by increasing the number of minute holes in the mesh plate.
Another object of the present invention is to improve liquid tightness of the device without limiting the vibration of a horn on the ultrasonic pump.
Another object of the present invention is to provide a structure which will not allow any excess liquid not atomized to flow out of the device.
A further object of the present invention is to enable effective utilization of liquid with which the device has been filled.
A further object of the present invention is to provide an inhaler, as well as a method of controlling the inhaler, in which it is possible to achieve automatic, intermittent spraying that conforms to the breathing of the user.
An ultrasonic atomizer according to the present invention comprises an ultrasonic pump comprising a pump shaft formed to have a pump bore passing through it axially and having open upper and lower ends, and an ultrasonic vibrator mounted on the pump shaft in the vicinity of the midpoint with respect to the axial direction, a liquid vessel provided at a position at which it is penetrated by a lower end of the pump shaft, a mesh plate placed on an upper end face of the pump shaft and formed to have a multiplicity of minute holes, and a biasing resilient member for biasing the mesh plate toward the upper end face of the pump shaft.
The pump shaft also is vibrated in the axial direction by vibration of the ultrasonic vibrator, whereby the liquid inside the liquid vessel is pumped up through the pump bore of the pump shaft. Since the mesh plate is urged against the upper end face of the pump by the resilient member, the mesh plate also vibrates by following up the motion of the pump shaft. Owing to the fact that the mesh plate is vibrated, and by virtue of the fact that the mesh plate is biased by the resilient member, the mesh plate acts as a type of valve which opens and closes the opening at the upper end of the pump bore in the pump shaft. The liquid pumped when the valve is opened is supplied to the mesh plate. When the valve is closed, the liquid is passed through the mesh plate so as to be atomized and sprayed. Since liquid in the amount pumped is atomized, good balance is achieved between the amount of liquid pumped and the amount of liquid atomized, and the spraying operation carried out is efficient and stable.
Since the mesh plate should be brought into pressured contact with the upper end face of the pump shaft at least in the vicinity of the opening at the upper end thereof, it is preferred that the following structure be adopted:
In a preferred embodiment, the upper end face of the pump shaft is formed to have a shape in which the upper end face is slightly and smoothly curved so as to attain maximum height at the position of the opening in the upper end of the pump bore and diminish in height as the periphery is approached.
In case of an arrangement in which the mesh plate is biased by the resilient member at a peripheral edge extending outwardly from the upper end face of the pump shaft, the mesh plate curves slightly. The curvature of the upper end face of the pump shaft, the elastic force of the resilient member and the strength of the mesh plate are decided in such a manner that the degree to which the mesh plate curves is less than the degree of curvature of the upper end face of the pump shaft.
In another embodiment, the upper end face of the pump shaft is formed to have a protuberance which projects in an area that includes the opening in the upper end of the pump bore.
In another embodiment, the mesh plate is formed to have a shape in which the central portion thereof is bent or curved slightly so as to point downward.
In a further embodiment, the biasing resilient member is a compression coil spring having a coil diameter which becomes progressively smaller as the mesh plate is approached, in such a manner that the mesh plate is biased at a position thereof situated on the upper end face of the pump shaft.
As set forth in the above-mentioned document, it is preferred that the mesh plate used be formed in such a manner that the minute holes flare outwardly in the dire
Asai Kei
Obata Masaru
Yamamoto Hirohito
Lewis Aaron J.
Morrison & Foerster / LLP
Omron Corporation
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