Fluid sprinkling – spraying – and diffusing – Including supply holder for material – Moving solid surface engages material to be sprayed
Reissue Patent
2001-03-16
2003-04-15
Douglas, Lisa A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including supply holder for material
Moving solid surface engages material to be sprayed
C239S590000, C222S321700, C222S385000
Reissue Patent
active
RE038077
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fluid medicine delivery device, and, more particularly, the invention is directed to a microdispensing ophthalmic pump for delivering a microdose of ophthalmic fluid.
2. Description of the Prior Art
U.S. Pat. No. 5,152,435 (hereinafter “the '435 patent)”, entitled “OPHTHALMIC DISPENSING PUMP”, discloses a manually operated dispensing pump capable of delivering a precise quantity of ophthalmic solution to the surface of an eye in a desired spray pattern with an impact pressure on the eye that is comfortably tolerable by an individual and was issued to a co-inventor, Ben Z. Cohen, of this patent. The '435 patent is incorporated by reference herein, including the extensive discussion of the shortcomings of the prior art. The spray pump of the '435 patent is substantial improvement over the prior art, capable of delivering doses of ophthalmic fluid such as 50 microliters in the previously described manner. However, often a dose of much less than 50 microliters of ophthalmic fluid may be required to be delivered in the manner described above. Since a reduction in the size of a dosage inherently decreases the impact force exerted by the dose onto an eye, the administration of fluid by the '435 patent would be even more comfortably tolerable than that disclosed therein with a reduction in the size of the dose the '435 pump could deliver. Also, some medications can have toxic effects, even at doses as small as 50 microliters, and so doses of less than 50 microliters would be better tolerated.
It is a primary object of the subject invention to provide a manually operated microdispensing pump for delivering a microdose of ophthalmic solution as small as 5 microliters.
Also, it is an object of the subject invention to provide a manually operated microdispensing pump capable of repeatedly administering a full and proper microdose as small as 5 microliters.
SUMMARY OF THE INVENTION
The above-mentioned objects of the present invention are achieved by a new and improved manually operated microdispensing pump for delivering ophthalmic fluid. In particular, the new and improved manually operated microdispensing pump will enable an individual to repeatedly deliver a predetermined microdose of ophthalmic fluid.
In the preferred embodiment, the microdispensing pump of the subject invention is formed to be substantially cylindrical with one end being formed as a reservoir for storing the ophthalmic fluid intended to be dispensed. A pump body is threadedly secured to the reservoir with a cylindrical inner body formed therein which projects along a central axis into the reservoir. A dip tube is provided to communicate fluid from the reservoir to the inner body of the pump body. A pump mechanism is disposed within the inner body which urges fluid from the reservoir and through the pump of the subject invention. The pump mechanism comprises an inlet check valve element for regulating the flow of the fluid from the reservoir into the inner body, a cylindrical piston slidably disposed and sealingly supported within the inner body, an elongated poppet extending from the inner check valve element and through the inner body in a spatial relationship with the piston, an outlet check valve element for regulating flow of the fluid out of the inner body and a spring for urging the cylindrical piston into an upward position in contact with a head formed on the end of the support opposite the inlet check valve element.
The microdispensing pump of the subject invention further comprises a dispensing cap mounted onto the cylindrical piston and formed with an outlet chamber which communicates with the inner body, the communication therebetween being controlled by the outlet check valve element, and a slender discharge nozzle communicating the outlet chamber with the periphery of the dispensing cap. An actuator is slidably disposed adjacent the dispensing cap and substantially within the pump body.
Once primed with ophthalmic fluid within the inner body, the pump dispenses ophthalmic fluid with a downward translation of the actuator, the dispensing cap and the piston within the inner body. As the piston translates within the inner body, the volume therein is decreased with an accompanying increase in pressure of the ophthalmic fluid contained within the inner body. The check valve elements are both normally closed and contribute to the pressure build-up of the fluid. Eventually, the compressed ophthalmic solution will force the outlet check valve element open, thereby allowing fluid to enter the outlet chamber and the discharge nozzle and force out fluid previously drawn therein. The fluid is delivered in a non-aerosolized jet stream as a series of droplets. A spring is provided to urge the outlet check valve element into a closed position quickly after being forced open. The piston, having completed its downward translation, translates upward into contact with the head of the poppet due to the urging of the spring acting on the piston. As the piston comes into contact with the head of the poppet, the volume within the inner body is increased and the accompanying pressure decreased. The reduction of pressure within the inner body creates a suction effect which urges the inlet check valve element into an open position and draws fluid from the reservoir into the inner body. As pressure builds within the inner body due to the added fluid, the inlet check valve element will be urged into a closed position allowing the pump mechanism to be used again.
The new and improved manually operated microdispensing pump of the subject application uses a spring biased outlet check valve element and a limited-travel inlet check valve element to operate under the negligible pressures and strokes associated with the delivery of microdoses of fluid. In the preferred embodiment, a spring is applied to a stainless steel ball to form the outlet check valve, which is biased to a normally closed position. The suction created by the pump mechanism to draw fluid therein may affect the microdose of the pump if fluid disposed in the nozzle and the outlet chamber is drawn into the inner body due to the suction effect. During operation of the pump, the spring urges the outlet check valve element into a closed and seated position prior to suction being created in the inner body and ensures that a proper and full microdose of the ophthalmic fluid is maintained within the nozzle and the outlet chamber, unaffected by the suction effect.
An inlet check valve element is provided to regulate the flow of ophthalmic fluid into the pump of the subject invention. Since the delivery of microdoses as small as 5 microliters involves a negligible stroke of the inlet check valve element, a protrusion is disposed opposite the inlet check valve element which restricts the check valve element's range of motion and prevents the check valve element from simply shuttling during usage. The motion of the inlet check valve element is limited so that in an open position the volume displaced by the inlet check valve element in travelling from a closed position to an open position is less than the volume of the dose being dispensed by the pump. In the preferred embodiment, this volume is the swept volume of an inlet check valve ball and is calculated by taking the product of the clearance between the inlet check valve ball and the protrusion times the cross-sectional area of the inlet check valve ball: (clearance)×[&pgr;×(radius of the ball)
2
]. Although a ball is preferred, any shape inlet check valve element may be used, such as a disk, with the swept volume being determined by the product of the clearance between the inlet check valve element and the protrusion times the largest cross-sectional area of the inlet check valve element measured in a plane perpendicular to the flow of fluid through the check valve. Thus, one feature of the new and improved manually operated microdispensing pump of the subject invention is a valve arrangement
Cohen Ben Z.
Kelly Nigel
Cohen Ben Z.
Douglas Lisa A.
Hoffmann & Baron , LLP
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