Abstract: A hypodermic syringe has a barrel, a piston with plunger located in the barrel cavity, an elongated body on the barrel forward end and a needle releasably secured to the body end. A sheath slidingly received onto the elongated body has arms with openings on their end portions which can be locked onto pins on the band exterior. The sheath also has shields which normally extend outwardly. A spring-loaded actuator sleeve is slidingly received on the sheath. When the plunger has emptied the barrel cavity, further movement releases the sheath arms from the pins and the spring-loaded actuator moves over the shields closing about the needle.

Abstract: A hypodermic syringe and needle combination with a releasable, automatic needle enclosing sheath. A syringe barrel having an open and a closed end includes first and second longitudinally extending guide channels for guiding push rods secured to the thumb platform of a plunger rod. Ball-end engaging sockets are located at the ends of the guide channels for capturing ball-ends secured to the needle sheath which is slidably supported and displaceable between (1) a first position where the needle sheath is locked by engagement of the ball-ends in the sockets and which exposes the needle, and (2) a second position where the needle sheath encases the needle. The needle sheath is spring biased so that it travels from the first position to the second position when the ball-ends are released from the sockets by pressure applied on the thumb platform which causes the pushrods to push the ball-ends out of the sockets.

Abstract: A needle sheath for completely encasing the needle of a disposable syringe is provided as a slidable attachment to the end of the syringe. The sheath is spring loaded. A push-button locking mechanism keeps the sheath in its unactivated position, leaving the hypodermic needle exposed, as needed for use. After use of the syringe, activating the button-locking mechanism causes the sheath to be driven by the spring mechanism to cover the length of the needle. The end flaps of the sheath that were held apart by the hypodermic needle close inward and overlap, completely encasing the needle.