Patent ID: 8029279
Filing Date: 2011-10-04
Classification: A61M,F16F

Abstract:
1. An improved dental syringe having: a) a hollow tubular syringe body, b) a hollow needle communicating with the hollow of the syringe body, c) a reciprocal tubular needle sheath disposed on the exterior of the syringe body, d) a spring engaging the syringe body and the sheath and expandable to move the sheath to cover the needle point, and e) 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, wherein the improvement comprises: a non-uniform helical spring having multiple 360° turns, each turn uniformly spaced from adjacent turns, each 360° turn comprising alternating angled portions and flat portions, the angled portions being at an angle to a plane perpendicular to an axis through the center of the helical spring and the flat portions being substantially parallel to the plane perpendicular to the axis, a first finger grip attached to or integral with the top of the syringe barrel, a locking collar integral with or attached to the first finger grip, said locking collar having two fingers extending laterally over the barrel and positioned to retain the sheath in a retracted position, and a second finger grip on the end of the plunger.