Method and device to protect syringes and similar medical instruments

Abstract

A needle-stick safety syringe includes an inner tubular body, plunger, and needle extending from a distal end of said inner tubular body, an outer tubular housing concentrically and slidingly surrounding at least a portion of the inner tubular body and biased apart from the inner tubular body. A recess is defined within an interior wall surface of the outer tubular housing, and a latch attached to a distal end of the inner tubular body. The latch includes a ring-shaped collar attached to the distal end of the inner tubular body and includes a cantilevered push-stop. A portion of the cantilevered push-stop is sized to fit within the recess when the latch is sufficiently disposed within the outer tubular housing.

What is claimed is:  
     
         1 . A needle-stick safety syringe, comprising: 
 an inner tubular body, plunger, and needle extending from a distal end of said inner tubular body;    an outer tubular housing concentric with and sized to fit around at least a portion of said inner tubular body and to slide freely thereon;    a spring disposed to bias apart said inner tubular body and said outer tubular housing;    a recess defined within an interior wall surface of said outer tubular housing; and    a latch attached to a distal end of said inner tubular body, said latch including a ring-shaped collar permanently attached to said distal end of said inner tubular body and having an outer diameter sized to slide freely within said outer tubular housing and further including a cantilevered push-stop, said cantilevered push-stop including a portion sized to fit within said recess when said latch is sufficiently disposed within said outer tubular housing, said latch push-stop engaging against a distal edge of said outer tubular housing to oppose bias of said spring;    wherein when said cantilevered push-stop is urged away from said outer tubular housing, said spring biases said outer tubular housing over said latch and said recess engages a portion of said push-stop.    
     
     
         2 . The syringe of  claim 1 , wherein said recess defines an annular shape within said interior wall surface of said outer tubular housing.  
     
     
         3 . The syringe of  claim 1 , wherein said recess is disposed adjacent a proximal end of said outer tubular housing.  
     
     
         4 . The syringe of  claim 1 , further including an exterior trigger disposed on an outer surface of said outer tubular housing adjacent a distal end thereof; 
 wherein user-exerted force on said exterior trigger urges said cantilevered push-stop away from said outer tubular housing.    
     
     
         5 . The syringe of  claim 4 , wherein said exterior trigger is a cantilever trigger.  
     
     
         6 . The syringe of  claim 4 , wherein said exterior trigger is selected from a material group consisting of (a) rubber, (b) plastic, and (c) flexible metal.  
     
     
         7 . The syringe of  claim 1 , wherein said spring is disposed within said outer tubular housing.  
     
     
         8 . A needle-stick safety syringe, comprising: 
 an inner tubular body, plunger, and needle extending from a distal end of said inner tubular body;    an outer tubular housing concentric with and sized to fit around at least a portion of said inner tubular body and to slide freely thereon;    a spring disposed within said outer tubular housing to bias apart said inner tubular body and said outer tubular housing;    a recess defining an annulus within an interior wall surface of said outer tubular housing adjacent a proximal end of said outer tubular housing; and    a latch attached to a distal end of said inner tubular body, said latch including a ring-shaped collar permanently attached to said distal end of said inner tubular body and having an outer diameter sized to slide freely within said outer tubular housing and further including a cantilevered push-stop, said cantilevered push-stop including a portion sized to fit within said recess when said latch is sufficiently disposed within said outer tubular housing, said latch push-stop engaging against a distal edge of said outer tubular housing to oppose bias of said spring;    wherein when said cantilevered push-stop is urged away from said outer tubular housing, said spring biases said outer tubular housing over said latch and said recess engages a portion of said push-stop.    
     
     
         9 . The syringe of  claim 8 , further including an exterior trigger disposed on an outer surface of said outer tubular housing adjacent a distal end thereof; 
 wherein user-exerted force on said exterior trigger urges said cantilevered push-stop away from said outer tubular housing.    
     
     
         10 . The syringe of  claim 9 , wherein said exterior trigger is a cantilever trigger.  
     
     
         11 . The syringe of  claim 9 , wherein said exterior trigger is selected from a material group consisting of (a) rubber, (b) plastic, and (c) flexible metal.  
     
     
         12 . A method of fabricating a needle stick safety syringe, comprising the following steps: 
 (A) providing an inner tubular body, plunger, and needle extending from a distal end of said inner tubular body;    (B) providing an outer tubular housing concentric with and sized to fit around at least a portion of said inner tubular body and to slide freely thereon;    (C) disposing a spring within said outer tubular housing to bias apart said inner tubular body and said outer tubular housing;    (D) defining an annulus-shaped recess within an interior wall surface of said outer tubular housing adjacent a proximal end of said outer tubular housing; and    (E) attaching a latch to a distal end of said inner tubular body, said latch including a ring-shaped collar permanently attached to said distal end of said inner tubular body and having an outer diameter sized to slide freely within said outer tubular housing and further including a cantilevered push-stop, said cantilevered push-stop including a portion sized to fit within said recess when said latch is sufficiently disposed within said outer tubular housing, said latch push-stop engaging against a distal edge of said outer tubular housing to oppose bias of said spring;    wherein when said cantilevered push-stop is urged away from said outer tubular housing, said spring biases said outer tubular housing over said latch and said recess engages a portion of said push-stop.    
     
     
         13 . The method of  claim 12 , further including: 
 disposing an exterior trigger on an outer surface of said outer tubular housing adjacent a distal end thereof;    wherein user-exerted force on said exterior trigger urges said cantilevered push-stop away from said outer tubular housing.    
     
     
         14 . The method of  claim 13 , wherein said exterior trigger is a cantilever trigger.  
     
     
         15 . The method of  claim 13 , wherein said exterior trigger is selected from a material group consisting of (a) rubber, (b) plastic, and (c) flexible metal.  
     
     
         16 . A method of preventing re-use of a needle stick safety syringe, comprising the following steps: 
 (A) providing a syringe having an inner tubular body, plunger, and needle extending from a distal end of said inner tubular body;    (B) disposing an outer tubular housing concentric with and sized to fit around at least a portion of said inner tubular body and to slide freely thereon, said outer tubular housing having an interior wall defining a recess and said outer tubular housing being biased away from a said needle when said syringe is to be used;    (C) attaching a latch to a distal end of said inner tubular body, said latch including a ring-shaped collar permanently attached to said distal end of said inner tubular body and having an outer diameter sized to slide freely within said outer tubular housing and further including a cantilevered push-stop, said cantilevered push-stop including a portion sized to fit within said recess when said latch is sufficiently disposed within said outer tubular housing, said latch push-stop engaging against a distal edge of said outer tubular housing to oppose bias of said spring;    wherein after said syringe has been used, said cantilevered push-stop is urged away from said outer tubular housing such that said outer tubular housing is biased to cover said latch and said recess engages a portion of said push-stop, wherein said needle is sheathed within a distal region of said outer tubular housing thereby preventing re-use of said syringe.    
     
     
         17 . The method of  claim 16 , wherein said recess is an annulus-shaped recess.  
     
     
         18 . The method of  claim 16 , wherein said recess is defined adjacent a proximal end of said outer tubular housing.  
     
     
         19 . The method of  claim 16 , further including disposing a spring within said outer tubular housing to bias said outer tubular housing relative to said inner tubular body.