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Disposable syringe with automatic needle retraction

  • US 5,125,898 A
  • Filed: 10/15/1991
  • Issued: 06/30/1992
  • Est. Priority Date: 03/22/1990
  • Status: Expired due to Term
First Claim
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1. A disposable syringe assembly, comprising:

  • a barrel having a proximal end and a distal end and an internal central bore;

    a tubular plunger having a closed proximal end, said plunger being telescopingly insertable within the proximal end of said central bore of said barrel and adapted for sealed, sliding reciprocating movement therewithin;

    needle attachment means mounted around the inner wall of said barrel, said needle attachment means being adapted for receiving a hypodermic needle mountable therein and having a releasable hub portion adapted for movement within said central bore of said barrel when released;

    a plunger distal seal member mounted on the distal end of said tubular plunger, said plunger distal seal member having a releasable hub portion adapted for sealed sliding movement within said tubular plunger when released, said plunger distal seal member closing and sealing the distal end of said plunger prior to release of said hub portion of said plunger distal seal member, the interior of said tubular plunger being relatively evacuated;

    said releasable hub portions of said needle attachment means and said plunger distal seal member being releasable in sequence and lockingly engageable with one another upon application of a predetermined longitudinal axial force on said plunger, the distal end of said barrel having an opening therein exposing the distal faces of said releasable hub portions of said plunger distal seal member and said needle attachment means to the atmosphere;

    said releasable hub portions of said needle attachment means and said plunger distal seal member being forced, when engaged with one another and released, into the relatively evacuated interior of said plunger by differential pressure between said evacuated interior and the atmosphere.

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