Importance

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Abstract

A hypodermic jet injector employing self-contained, patient fillable, thin-walled disposable ampules. Each ampule includes an elongate plastic body with an injection orifice at a first end, an internal propellant at a closed second end, and a double piston slidably and sealingly mounted within the body entirely between the orifice and the internal propellant, and also includes an auxiliary access opening in the ampule side wall. An ampule chamber with a corresponding access opening in its_side wall is provided to receive and support the thin-walled ampule. The main body of the ampule is molded with draft angles, and the double piston construction includes a soft rubber plunger and a relatively hard plunger to the front and rear, respectively, of the auxiliary access opening in the ampule, with the two plungers interconnected by a connecting rod spanning the central section of the ampule. The ampule chamber is provided with a draft angle in the front section of its bore adjacent to the soft plunger in the ampule, and a straight bore in the rear section adjacent to the hard plunger in the ampule. The injector includes a high-resolution metered filling device located parallel to the ampule chamber and including a piston engagement member which is laterally movable into contact with the connecting rod, which consequently moves under control of the filling device. The metered filling device includes a digital dosage display including a drum bearing a plurality of dosage values in integer form arranged in a spiral pattern on its surface, and a dosage selection window positioned so as to expose a single dosage value at a time.

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First Claim