Media dispenser

Details Media dispenser Media dispenser

1999-08-31

2001-10-30

Shaver, Kevin (Department: 3754)

Dispensing

With discharge assistant

With movable nozzle interconnected therewith

C222S321700, C222S420000, C222S422000

Reexamination Certificate

active

06308867

ABSTRACT:

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a dispenser for releasing flowable media by pressurizing. Particularly liquid media, but also pasty, powdery and/or gaseous media are suitable. The dispenser is held and simultaneously actuated for discharge single-handedly. Most or all parts are injection molded from plastics. The medium may be discharged atomized or delivered in discrete clusters or droplets of a colume of at least 5 or 15 &mgr;l and at the most 40 or 25 &mgr;l while containing medical active substances for eye treatment, or the like.
Such dispensers need microbiological sealing to prevent the stored medium from germ contamination gaining access from without. The medium is to be protected from such detrimental effects during a long shelf life not only prior to the dispensers first-time use (priming) but also after the initial discharge. The dispenser may be made for a single dose discharge or for moving the actuator only unidirectional without return or suction stroke up to being totally emptied. The total input of medium may be in a single conveying chamber right from the start without provision of any additional medium reservoir. The chamber volume is then variable for pressurized medium delivery. However, the dispenser or its actuator may also operate reversible, namely repeatedly via a working stroke for pressurized delivery directly followed by a return stroke for sucking a further medium dose into the chamber. After discharge of the medium dose the microbiological seal is always to be reproduced until the next discharge. This is not necessary in the case of a disposable dispenser.
For this seal either a single valve or several valves may be suitable. The valves closing gaps sequentially follow within the outlet duct in the flow direction. The last downstream valve is as near as possible to the medium outlet or its bound which is formed by the transition between an inner circumference and a transversely adjoining end face. At this transition the medium detaches from all inner circumferences or inner dispenser surfaces for release to the environment. Downstream thereof the medium may be still guided on external dispenser faces.
OBJECTS OF THE INVENTION
An object of the invention is to provide a dispenser which avoids the drawbacks of known configurations and achieves advantgeous effects of the aforementioned kind. Another object is to ensure a repeated microbiological seal against germ ingress through the bounds of the outlet or of inflow openings. Other objects are simple handling or uncomplicated construction. A further object is to provide a dispenser for modular composition permitting adaptation to media differing in flowability.
SUMMARY OF THE INVENTION
According to the invention the dispenser comprises a valve closing with high surface pressure. Its closing gap may also form the named opening bound. Thus the closing gap extends up to the outermost possible location of the outlet duct at which the medium detaches. With the valve closed this location is a microbiological seal. Thus, at the most, germs are able to collect on the permanently freely accessible dispenser outside but have no upstream access to internal dispenser faces past the tight closing gap.
The closing force is not reduced until the medium pressure in the outlet duct has attained at least 0.7 or 1 or 1.4 bar. The valve could be opened by fluid control once the medium pressure has attained this value. Otherwise it is opened pressure independently by pure mechanical actuation. The cited sealing effect and the germ ingress prevention with the valve open may also be improved by keeping the valves operating travel smallest. The maximum relative opening or closing travel of the two valve bodies is less than 2 mm, 1 mm, 0.7 mm or 0.4 mm, e.g. 0.3 mm. On droplet discharge the medium then emerges practically with zero pressure or by capillary creeping through the valve gap. Still further upstream means such as a pump for generating a medium pressure higher than the aforementioned pressures, i.e. two to five times higher, may be provided. This medium pressure amounts to e.g. at least 4, 6 or 7 bar.
To nevertheless attain a medium discharge at the outlet under reduced or without pressure, a throttle gap adjoines the valve upstream. This gaps passage cross-section is significantly smaller than that of the opened valve and may be varied as a function of the medium pressure. For example, the open valve cross-section may be at least 2, 40 or 50 times more than the throttle cross-section.
Upstream of the end valve or throttle gap a further valve or throttle is provided in the outlet duct. E.g. the medium flow is prethrottled in constant cross-sections already upstream of the throttle gap or end valve. The flow of the medium is also throttled at the transition from the converging chamber to the outlet duct or shut off microbiologically sealed at this transition. The further valve is a spring-loaded outlet or pressure relief valve. For forming the closing gap the closing faces of each of the valves may have only linear contact or maximum closing pressure along a sole e.g. annular micro line for maximum specific areal pressures. Therefore one of the closing faces of each valve is a sharp edge bounded by two angularly adjoining flanks or a spherical surface.
The medium is manually conveyed by a thrust piston pump or a flexible squeeze receptacle, such as a tube. In the latter the dispensers complete valve control is arranged in the constricted tube tip which is in one part with the tube shell. In the case of a piston pump the cylinder or piston runs commonly with the medium outlet counter the opening direction of the movable valve bodies during the pump stroke.
Irrespective of the described constructions a droplet former, particularly in the upside-down position of the dispenser with the medium outlet held downwards, accumulates a freely exposed medium droplet of a metered volume. The droplet then hangs adheringly suspended on the dispenser with a transition diameter smaller than its largest diameter. Thus the droplet does not detach until its lower end face comes into contact with a counter face, e.g. the eyeball. With this the droplet commences to flow onto the counter face. For the droplet the accumulator has a convex and/or concave adhering face which may be spherical, smooth or polygonal to increase the areal size at a same plan view area. This face directly adjoins the end valves closing faces and is formed by the end of a needle traversing the medium outlet.


REFERENCES:
patent: 1002995 (1911-09-01), Johnson
patent: 2281051 (1942-04-01), Roger
patent: 2832513 (1958-04-01), Tubin
patent: 3107035 (1963-10-01), Cholet
patent: 4770323 (1988-09-01), Debard
patent: 4830284 (1989-05-01), Maerte
patent: 5147073 (1992-09-01), Cater
patent: 5725131 (1998-03-01), Bell et al.
patent: 5785208 (1998-07-01), Dobbs et al.
patent: 35 03 354 A1 (1985-01-01), None
patent: 196 27 228 A1 (1996-07-01), None
German Patent Office search report on European patent application No. 19840723.8, dated Apr. 20, 1999.

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