Surgery – Liquid medicament atomizer or sprayer – Ultrasonic
Patent
1995-04-11
2000-05-16
Weiss, John G.
Surgery
Liquid medicament atomizer or sprayer
Ultrasonic
12820014, 2391022, A61M 1100
Patent
active
060622121
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to dispensing apparatus for dispensing liquid as an atomised mist and in particular but not exclusively for dispensing medicaments for inhalation therapy.
BACKGROUND
It is known from GB-2240494A to provide dispensing apparatus in which a perforate membrane is vibrated such that liquid in contact with a rear face of the membrane is dispensed from a front face of the membrane as an atomised mist or spray. It is proposed that in the disclosed apparatus a predetermined dose is delivered by operation of a control circuit which regulates the dispensing period during which the membrane is vibrated, the supply of liquid being contained in a chamber of which the membrane constitutes a front wall.
A disadvantage of such an arrangement is that when not in use the liquid within the chamber is open to air through holes in the perforate membrane and may thereby be subject to evaporative losses or become bacteriologically contaminated or otherwise degraded.
A further disadvantage of such an arrangement is that variation in the rate at which liquid is dispensed through the membrane as a mist will result in variation in the total quantity delivered during the dispensing period.
SUMMARY OF THE INVENTION
According to the present invention there is disclosed dispensing apparatus comprising a housing defining a dispensing outlet, a perforate membrane having a front face exposed at the outlet and a rear face contacted in use by liquid to be dispensed, vibrating means connected to the housing and operable to vibrate the membrane to dispense droplets of the liquid through the membrane, liquid supply means connected to the housing and delivery means operable at successive actuations of the delivery means to deliver a respective metered quantity of the liquid from the liquid supply means into contact with the rear face of the membrane whereby in use a metered quantity of liquid is dispensible at the outlet by operation of the vibrating means for an operating period greater than the dispensing period required for the metered quantity to be dispensed through the membrane.
An advantage of such apparatus is that it facilitates the dispensing of all of the liquid coming into contact with the rear face of the membrane as a single dose. It is thereby possible to avoid contact between liquid and ambient air during periods of non-use between successive actuations. For pharmaceutical preparations this is particularly important since it may obviate the need for the use of preservatives in the liquid and avoids evaporative losses.
The liquid supply means conveniently comprises a pipette and the delivery means comprises a piston movably mounted in the pipette to displace, liquid therefrom and indexing means operable to move the piston at successive actuations through a respective distance to thereby displace a metered quantity of liquid.
Alternatively the liquid supply means may comprise a reservoir containing liquid and the delivery means may comprise a metering pump connected to the reservoir, the metering pump comprising a cylinder defining a chamber and a piston reciprocatably mounted in the cylinder to displace a metered volume of liquid from the chamber at each actuating stroke.
Alternatively the delivery means may comprise an electrically driven pump operable to deliver a flow of liquid and control means operable to turn the pump on and to turn the pump off after delivery of the metered volume of liquid.
In an alternative apparatus the liquid supply means comprises a pressurised dispensing container within which a supply of liquid is maintained under pressure and the delivery means comprises a metering valve operable to release from the container a metered volume of the liquid.
In a further alternative apparatus the liquid supply means comprises a plurality of cells each containing a metered volume of liquid and the delivery means comprises a dispensing station operable to release at each actuation thereof the contents of a respective cell.
Preferably the housing comprises an annular m
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Barnes Paul
Brace Geoffrey
Davison John Robin
Bespak plc
Srivastava V.
Weiss John G.
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