Abstract: An improved safety IV placement device includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after placement of the IV cannula and removal of the needle from within the cannula. An internal spring, which engages the sheath, expands to move the sheath to cover the needle point prior to placement of the IV cannula and after the needle is removed from the indwelling cannula. The spring is a non-uniform helical spring having multiple 360 turns each turn uniformly spaced from adjacent turns.

Abstract: An improved safety hypodermic syringe for dental applications which further includes first finger grip, preferably a thumb ring, on the end of the plunger, forward finger holders and a lock mechanism, which includes extending fingers for grasping the top of the reciprocal sliding sheath. The syringe assembly also includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after delivering contents from the syringe body. The fingers, preferably biased by a living hinge hold back the locking ring while the dentist administers anesthesia through the syringe. An internal spring, which engages the syringe body and the sheath, expands to move the sheath to cover the needle point. The spring is a non-uniform helical spring having multiple 360° turns with each turn uniformly spaced from adjacent turns.

Abstract: An improved safety hypodermic syringe includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body, a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after delivering contents from the syringe body, and a spring engaging the syringe body and the sheath and expandable to move the sheath to cover the needle point, where the spring is a non-uniform helical spring having multiple 360° turns each turn uniformly spaced from adjacent turns, each 360° turn comprising first and second alternating angled portions, the first of the alternating angled portions being at a first angle to a plane perpendicular to an axis through the center of the helical spring and the second angled portions being at a second lesser angle to the plane perpendicular to the axis.