Patent ID: 6139526
Filing Date: 2000-10-31
Classification: A61M

Abstract:
A single use hypodermic syringe comprisinga generally tubular envelope adapted to contain a fluid to be dispensed and containing a plunger for dispensing said fluid,said tubular envelope having a front dispensing end and a dispensing needle coupled to said front end, said front end having means for stopping the motion of said plunger after fluid has been dispensed,said plunger including an upper elongated member and a lower elongated member positioned with said upper member overlying said lower member and adapted to slide with respect to each other,said upper and lower members having engaging parts adapted to permit said upper and lower members to engage each other and to move as a unit toward said fluid dispensing end of said envelope as a fluid dispensing operation is performed, said engaging parts including a hook-like process on said upper member and a depression in the top surface of said lower member in which said hook-like process is seated when said plunger is in position to perform a dispensing operation,said upper member having a slanted wall positioned at its rear end and said lower member having a slanted wall at its front end, said slanted walls engaging each other and assisting in causing said plunger to move forwardly in said envelope in performing a dispensing operation,said lower member having a front end adapted to engage and bear against said front end of said envelope as a stop to stop the forward motion thereof,said upper member having an enlarged end wall outside said envelope usable for manually pressing said plunger forwardly as a unit inside said envelope in performing a fluid dispensing operation,said upper member being seated on said lower member as described preparatory to performing a fluid dispensing operation, at the end of which continued dispensing pressure applied to said enlarged end wall forces said hook-like process to slide on said lower member out of said notch whereby said upper member slides away from and out of contact with said lower member and is thus permanently out of contact therewith and no additional dispensing operation can be performed thereby.