Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1995-05-09
1997-04-29
Millin, V.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604228, 604110, A61M 5315
Patent
active
056244088
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates generally to a syringe and more particularly, although not exclusively, to a syringe which is intended for one time use only, i.e. a so-called disposable syringe, and which is of the kind that includes a rod which is fitted in a container for reciprocating movement in relation thereto and one end of which has the form of or coacts with a needle, a piston which is able to coact with the rod, and coupling means which function to connect and disconnect the piston to and from the rod.
The present invention is primarily intended to provide a syringe of this kind which is constructed so as to enable the container to be filled with liquid through the needle and the liquid then dispensed through said needle and so that after this the container can no longer be filled with and emptied of liquid.
The present invention pertains in particular to a syringe of the kind in which the coupling means which function to connect and disconnect the piston to and from the rod adopt an active coupling state over a movement path in which the piston is drawn by the rod from a position close to the needle to a position in which it is distanced from said needle, and is brought to a disconnected state when the piston is pressed by the rod through an adapted short movement path in a direction towards the needle, said coupling means comprising support and/or slide surfaces which are provided on that part of the rod which lies proximal to the needle and which coact with opposing support and/or slide surfaces on the piston in the coupled state of the rod and the piston.
BACKGROUND ART
Disposable syringes of the aforedescribed kind, by which is meant syringes that can only be used once, can be divided into a number of function-dependent categories with regard to their function-dependent characteristics.
A first syringe category is exemplified by the syringe illustrated and described in the International Patent Publication PCT/SE88/00634, International Publication No. WO 89/04677. In the case of this syringe, the rod can be twisted in relation to the container and the piston so as to move the coupling means on the one hand to a connecting state and on the other hand to a disconnecting state, as the rod is twisted. Thus, with this type of syringe, it is necessary that the piston is unable to twist or rotate or at least not essentially, at the same time as the rod is twisted in relation to the container.
It is thus of great importance with this category of syringe that means are provided to ensure that the piston will not twist together with the rod.
In a second syringe category, the rod, or red unit, carries a piston or piston unit and moves backwards and forwards in the container without twisting, and the outer surface of the piston unit and the inner surface of the container include means which mutually coact to lock the piston in a lowermost position. Examples of these prior art syringe assemblies are described and illustrated in prior publications U.S. Pat. Nos. 4,391,272; 4,775,364; PCT/GB87/00728 with respective International Publication Nos. WO 88/02640; GB-A 2,197,792 and FR-A 2,613,628.
A third category of disposable syringes includes a rod unit which is moved forwards and backwards in the container without twisting, and a piston unit which is fastened to the rod unit by means of a separate connecting part.
This connecting part is pivotally mounted on the rod part for rotation about a centre line on the rod, the piston and the container, and can be guided into to different rotational positions by grooves disposed on the piston unit.
An example of this type of syringe is described and illustrated in publication NO-A 163,263.
DISCLOSURE OF THE PRESENT INVENTION
TECHNICAL PROBLEMS
When studying the earlier known art as described above, while considering the comprehensive efforts that have been made to construct a disposable syringe which is well adapted for mass production at a cost which is comparable with the cost of manufacturing standard reusable syringes, it will be seen that
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patent: 4775364 (1988-10-01), Alles
patent: 5007904 (1991-04-01), Densmore et al.
patent: 5059179 (1991-10-01), Quatrochi et al.
patent: 5084017 (1992-01-01), Maffetone
patent: 5181912 (1993-01-01), Hammett
Alexander V.
Dille Safe AB
Millin V.
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