Patent ID: 7211064
Filing Date: 2007-05-01
Classification: A61M

Abstract:
1. A disposable syringe comprising: a needle cannula; a barrel having an inner surrounding barrel wall surface which surrounds an axis and which confines a passage, said passage having open lower and upper ends which are disposed opposite to each other in a longitudinal direction parallel to the axis, said inner surrounding barrel wall surface including a larger-diameter segment and a smaller-diameter segment which confine rear and front passageways respectively, and which are disposed proximate to said open lower and upper ends, respectively, to form a surrounding shoulder portion therebetween, said smaller-diameter segment including a front surrounding region and a rear surrounding region which is proximate to said surrounding shoulder portion, said larger-diameter segment including proximate and distal surrounding regions which are opposite to each other in the longitudinal direction and which are respectively proximate to and distal from said surrounding shoulder portion; a tubular needle seat including a grip member disposed to bring said surrounding gripped portion into engagement with one of said rear surrounding region and said proximate surrounding region, said grip member being configured to provide a resisting force that holds said surrounding gripped portion in position so as to prevent movement of said surrounding gripped portion relative to a respective one of said rear surrounding region and said proximate surrounding region during a piercing action of said needle cannula for a hypodermic or intravenous injection, and that permits disengagement of said surrounding gripped portion from said respective one of said rear surrounding region and said proximate surrounding region so as to enable a subsequent movement of said tubular needle seat relative to said inner surrounding barrel wall surface when said grip member is subjected to a first external force; a plunger which, in a position of use, is disposed to be movable in said larger-diameter segment, said plunger including a biasing member disposed between said shank portion and said tubular intermediate wall to bias said coupling rod towards the retracted position; a retaining member disposed to retain said thrust end in the position of use against biasing action of said biasing member; and a triggering member disposed to prevent said retaining member from retaining said thrust end in response to a second external force, thereby permitting said coupling rod to be biased towards the retracted position.