Syringe assembly with automatic safety sheild

Abstract

A safety shield for use with a hypodermic syringe device is disclosed. The safety shield is moveable relative to the syringe barrel between retracted position and a needle containing position. In the retracted position, the syringe device may be used to inject the needle into the patient. After the medication has been injected or as the needle is withdrawn from the patient, in its operative mode the shield automatically extends from its retracted position to a needle containing position to shield the point of the needle to prevent accidental sticks and without further input from the operator to render the syringe unusable after a single injection.

1 . A safety shield assembly for use with a syringe device having a hollow barrel defining a reservoir within which a medicament may be held, a forward projecting hypodermic needle in fluid communication with the reservoir, the syringe device further including a plunger rod slidable within and partially projecting rearward from the open proximal end of said syringe barrel, said plunger rod selectively moveable within the reservoir along a forward injection stroke, whereby medicament is expelled from the reservoir through the needle, said safety shield assembly comprising:
 a. an outer shield axially moveable relative to said syringe barrel between retained and needle-containing positions, said outer shield including a first engagement member arranged to engage a first catch member situated on said syringe barrel to retain said outer shield in a retracted position;   b. an actuation member located on said outer shield, whereupon actuation of said actuation member in the injection stroke direction causes said first engagement member to release from said first catch member to disengage said outer shield from said retained position and move said outer shield to said needle-containing position.   
     
     
         2 . The safety shield assembly of  claim 1 , wherein said outer shield additionally comprises a second engagement member located proximally from said first engagement member, said second engagement member arranged to engage a second catch member situated on said syringe barrel to prevent distal movement of said outer shield beyond said needle-containing position. 
     
     
         3 . The safety shield assembly of  claim 2 , wherein said outer shield additionally comprises a third engagement member located proximally from said first engagement member, said third engagement member arranged to engage said first catch member situated on said syringe barrel to prevent proximal movement of said outer shield once in said needle-containing position. 
     
     
         4 . The safety shield assembly of  claim 2 , wherein said second engagement member comprises an endwall of an elongated slot situated on said outer shield. 
     
     
         5 . The safety shield assembly of  claim 3 , additionally comprising a compression spring disposed between said syringe barrel and said outer shield, said compression spring provided for propelling said outer shield to said needle-containing position once said outer shield is disengaged from said retained position. 
     
     
         6 . A safety shield assembly for use with a syringe device having a hollow barrel defining a reservoir within which a medicament may be held, a forward projecting hypodermic needle in fluid communication with the reservoir, the syringe device further including a plunger rod slidable within and partially projecting rearward from the open proximal end of said syringe barrel, said plunger rod selectively moveable within the reservoir along a forward injection stroke, whereby medicament is expelled from the reservoir through the needle, said safety shield assembly comprising:
 a. an outer shield axially moveable relative to said syringe barrel between retracted and needle-containing positions, said outer shield including a first engagement member arranged to engage a catch member situated on said syringe barrel to retain said outer shield in a retracted position; and,   b. an actuation member located on said outer shield, whereupon manual actuation of said actuation member in the injection stroke direction causes said first engagement member to release from said first catch member to disengage said outer shield from said retained position to enable movement said outer shield to said needle-containing position preventing access to the sharp end of the needle.   
     
     
         7 . The safety shield assembly of  claim 6 , wherein said disengaged outer shield is moved to said needle-containing position by manual actuation in the injection stroke direction. 
     
     
         8 . The safety shield assembly of  claim 6 , additionally comprising a compression spring disposed between said syringe barrel and said outer shield, said compression spring provided for propelling said disengaged outer shield to said needle enclosing position. 
     
     
         9 . The safety shield assembly of  claim 6 , additionally comprising a finger flange extending radially from said syringe body, said actuation member arranged to abut with said finger flange when said outer shield reaches said needle-containing position to prevent distal movement of said outer shield past said needle containing position. 
     
     
         10 . The safety shield assembly of  claim 6 , wherein said outer shield additionally comprises a second engagement member located proximally from said first engagement member, and arranged to engage said catch member as said outer shield reaches said needle-containing position to prevent proximal movement of said outer shield. 
     
     
         11 . The safety shield assembly of  claim 6 , wherein said actuation member is arcuate in shape. 
     
     
         12 . The safety shield assembly of  claim 11 , wherein said outer shield is actuated simultaneously with actuation of the plunger along the injection stroke. 
     
     
         13 . The safety shield assembly of  claim 12 , wherein said outer shield and said plunger are actuated simultaneously by a user's thumb. 
     
     
         14 . The safety shield of  claim 11 , wherein said outer shield may be actuated after said plunger has been actuated along the injection stroke.