Safety syringe needle device with interchangeable and retractable needle platform
The syringe includes a barrel, a plunger, and an adapter for mounting the needle in the distal end of the barrel. The adapter includes a protrusion projecting away from the needle end and into the barrel defining an annular space between the barrel and the protrusion. The plunger and protrusion have complementary surfaces whereby the plunger may grip the adapter for removal of the adapter into the interior of the barrel after use. These complementary surfaces afford initial resistance to further axial movement of the plunger toward the adapter, signalling the user that further axial pressure will permanently lock the plunger and adapter to one another whereby, upon application of full axial pressure on the plunger, the complementary surfaces of the plunger and adapter permanently lock to one another to enable joint unitary movement of the plunger and adapter together with the needle carried by the adapter into the barrel. The adapter includes vent passages communicating between the central passage through the adapter and the annular space whereby air can be vented from the barrel after receiving fluid within the barrel and prior to injection. Thus, the syringe may be oriented in a vertical position needle end uppermost with the vent passages forming the most superior portion of the barrel interior whereby air may be vented.
1. A syringe comprising:
a hollow axially elongated barrel having distal and proximal ends;
a needle carrier releasably secured to said distal end of said barrel;
a hollow needle carried by said carrier and in communication with the interior of the barrel;
a plunger axially slidable in said barrel and having a thumbpress at a proximal end thereof and external to said proximal end of the barrel, said plunger including a bung adjacent an opposite end and within the barrel;
an element carried by said opposite end of said plunger and engageable with a mating element carried by said needle carrier, one of said elements snapping over another of said elements to secure the elements to one another in response to axial movement of said plunger toward said distal end of the barrel and into engagement with said carrier;
said element in engagement with said mating element carried by the needle carrier enabling detachment and removal of said carrier with said needle from said distal end of the barrel and withdrawal of said needle carrier and said needle into the barrel in response to axial sliding movement of the plunger away from the distal end of the barrel;
said needle carrier being threadedly engaged with the distal end of the barrel, said elements having surfaces interengageable with one another enabling rotation of said plunger to unthread said carrier from the barrel and withdrawal of the carrier and needle axially into the barrel.