Safety syringe

Details Safety syringe Safety syringe

1998-11-03

2000-10-17

Dawson, Glenn K.

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

604110, 604198, A61M 532, A61M 500

Patent

active

061324019

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to a safety syringe.


BACKGROUND TO THE INVENTION

With the increasing risk of infection through needle injuries, there is a demand for a syringe which can be used and disposed of in a manner which reduces the risk of such injury.


OBJECT OF THE INVENTION

It is an object of this invention to provide a safety syringe.


SUMMARY OF THE INVENTION

In accordance with this invention there is provided a syringe comprising: a generally tubular protective sheath carrying piston engaging formations and having a needle end and an opposite rear end; fluid pathway through the head and longitudinally through the body, the piston body being operatively locatable to extend within the sheath and be engaged by the piston engaging formations, with the piston head outside the sheath and connected to and in fluid communication with the piston body; the operatively located piston head and along the sheath to a discharged position, to thereby release the piston engaging formations, and grip the released piston, the barrel being oppositely slidable from the discharged position to withdraw the released piston substantially from the sheath to a safe locked position relative to the sheath, characterized in that the barrel is shaped and dimensioned to be slidable over the outside of the protective sheath and the piston body and sheath carry clips and stops to operatively lock the piston body relative to the sheath to hold a needle used with the syringe inside the sheath before and after use.
Preferably in a first embodiment of the invention the piston body has a front and a rear end, with front and rear clips thereon, and the sheath has stops at its rear end, the piston body clips and stops being arranged to enable the piston body to be inserted into the sheath with the rear piston body clips engaging the sheath stops and locking the piston body against withdrawal from and insertion into the sheath, in that rotational orientation with the sheath, and being further arranged to enable movement of the barrel to its discharged position to release the rear piston body clips, and to enable the front piston body clips to engage the stops on movement of the piston body to the safe locked position.
There is provided for the sheath to have a first and second axial keyway means, the first keyway means having a cross sectional shape designed to guide a clip rotating therein in use into the second keyway means, and the second keyway means having abrupt edges designed to prevent rotational movement of a clip therein in use.
Further, each of the first and second keyway means are a pair of diametrically opposed matching keyways, with the pairs located at 90 degrees to each other in cross-sectional orientation of the sheath.
Each keyway of a pair has a transverse clip stop, the clip stop of the first keyway pair being located further into the sheath interior than the clip stop of the second keyway pair.
Preferably, the front piston body clips of the piston body form keyway slides, and have opposed clipping formations, being a front formation which is able to slide over the stops in a forward direction only, and a rear formation which is able to slide over the stops in a withdrawal direction only.
The rear piston body clips of the piston body may have opposed clipping formations, being a forward clipping formation slidable over stops on insertion into the sheath, and a rear formation which abuts the stops when the piston body is slid into the sheath.
Preferably, the rear formation of the rear piston body clips is shaped to co-operate with the piston head, on movement of the piston head with the barrel at the end of a discharge stroke in use, to disengage the forward formation of the rear piston body clip from its stop in use.
Alternatively, the piston engaging formations on the sheath may include barbed flaps arranged to engage slots on the piston.
Preferably, these flaps are part of the sheath wall and project axially rearwardly from a hinged portion of the sheath at the needle end of the sheath, the

REFERENCES:
patent: 5320606 (1994-06-01), Jore
patent: 5656031 (1997-08-01), Thorne et al.

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