Dual-chamber safety hypodermic syringe

Details Dual-chamber safety hypodermic syringe Dual-chamber safety hypodermic syringe

2000-12-26

2002-10-22

Nguyen, Anhtuan T. (Department: 3763)

Surgery

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

Treating material introduced into or removed from body...

C128S919000, C604S220000, C604S240000

Reexamination Certificate

active

06468250

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a safety hypodermic syringe and, more particularly, to a dual-chamber safety hypodermic syringe, which is suitable for use to inject medicine into the body as well as to draw blood from the body, and enables the needle cannula to be safely received in an independent needle chamber after its service.
2. Description of Related Art
In regular safety hypodermic syringes, the plunger has catch means at the front side for catching the needle assembly. After the plunger had been pushed to the front side to squeeze medicine out of the barrel, the catch means is forced into engagement with the needle hub of the needle assembly. Therefore, the needle assembly is pulled backwards and received inside the barrel after a backstroke of the plunger. However, when the user pulls the plunger to the rear limit position, the plunger protrudes over the rear side of the barrel at a distance, and the length of the hypodermic syringe is relatively increased. Because the front side of the barrel is kept in an open status, the needle cannula tends to be forced out of the barrel again when hitting the plunger against an object accidentally. In order to eliminate this problem, another prior art may employ much effort forwards to the plunger to curve the metal needle cannula after the needle assembly has been moved backwards with the plunger inside the barrel. However, the needle cannula may be forced to pierce through the peripheral wall of the barrel when employing force forwards to the plunger to curve the needle cannula. There is still one another structure of safety hypodermic syringe, in which the plunger is broken and plugged into the front opening of the barrel again to curve the needle cannula of the needle assembly after the needle assembly had been received inside the barrel. However, it requires much effort to plug the plunger into the front opening of the barrel against the metal needle cannula and to curve the metal needle cannula, and an accident of piercing through the peripheral wall may still occur when curving the metal needle cannula.
Further, in order to prevent engagement of the catch means of the plunger with the needle hub of the needle assembly before the use of the safety syringe, a gap must be maintained between the plunger and the needle hub of the needle assembly. However, the presence of the gap causes the safety hypodermic syringe unable to be used to draw blood from the body. This design also causes a high cost of packing material to keep the gap in distance.
Therefore, it is desirable to provide an improved hypodermic syringe to mitigate and/or obviate the aforementioned problems.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide a dual-chamber safety hypodermic syringe, which enabling the needle assembly to be safely received in an independent needle chamber after its service, and preventing the needle cannula from being pushed forwardly or piercing sideways to the outside of the barrel to injure people by an accident. Another object of the present invention is to provide a dual-chamber safety hypodermic syringe, which is practical for use to inject medicine into the body as well as to draw blood from the body.
To achieve the object, the dual-chamber safety hypodermic syringe of the present invention includes a needle assembly, the needle assembly comprising a needle hub and a needle cannula mounted in the needle hub, the needle hub comprising a neck on the middle and an inlet on the neck in communication with the needle cannula, and a handle extended sideways from the periphery thereof; and a barrel, the barrel comprising a front side, a rear side, a medicine chamber and a needle chamber respectively extended in axial direction, an outlet in the front side of the barrel, the needle chamber having a front open side connected to the outlet and a rear open side extended through the rear side of the barrel, the medicine chamber having a closed front side and a rear open side extended to through the rear side of the barrel, a guide hole communicated between the medicine chamber and the needle chamber, a longitudinal sliding slot disposed in parallel to and in communication with the needle chamber, and a front retaining hole extended sideways from a front end of the longitudinal sliding slot; wherein the needle assembly is slidably mounted in the needle chamber such that when the handle is moved forwards along the longitudinal sliding slot and engaged into the front retaining hole, the needle assembly is locked in an extended position to hold the needle cannula outside said barrel and to keep the inlet in communication with the guide hole for enabling a liquid medicine or blood to pass through the medicine chamber, the guide hole, the inlet and the needle cannula. After the service of the safety hypodermic syringe, the handle is disengaged from the front retaining hole and then moved along the longitudinal sliding slot needle in the reversed direction to receive the needle assembly safely inside the needle chamber.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 4941883 (1990-07-01), Venturini
patent: 5263942 (1993-11-01), Smedley et al.
patent: 5298023 (1994-03-01), Haber et al.
patent: 5300038 (1994-04-01), Haber et al.
patent: 5498245 (1996-03-01), Whisson
patent: 5514107 (1996-05-01), Haber et al.
patent: 5709667 (1998-01-01), Carilli
patent: 5728073 (1998-03-01), Whisson

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