Full displacement retractable syringe
First Claim
1. A full displacement syringe, comprising:
- an elongated housing comprising a hollow barrel having a front end portion, and an inner surface;
a plunger configured to reciprocate in the barrel, the plunger having a retraction cavity within and a tubular nose in front with a leading wall having a removably sealed opening into the retraction cavity;
a retraction mechanism mounted in the front end portion of the barrel, the retraction mechanism comprising a needle and needle holder having a head, a biasing element tending to drive the needle holder rearwardly and a movable holding ring mounted on the head of the needle holder, said ring holding the retraction mechanism by contact with the inner surface of the barrel, wherein the retraction mechanism forms the bottom of a variable fluid chamber in the barrel;
a plunger seal forcibly slideably mounted near the front of the tubular nose of the plunger, said plunger seal being movable with the plunger in sliding contact with the inner surface of the barrel during fluid transfer operations;
a plunger seal restraint located on the barrel wall to restrain the plunger seal from forward movement after it has reached the bottom of the variable chamber without said restraint preventing the plunger nose from sliding forward through the plunger seal to operate the retraction mechanism;
whereby depression of the plunger to place the plunger seal at the bottom of the variable fluid chamber causes substantially full displacement of fluid from the barrel and further forward movement of the plunger causes the leading wall of the tubular nose of the plunger to operate the retraction mechanism by moving through the plunger seal to push the movable holding ring off the head of the needle holder, thereby initiating retraction.
1 Assignment
0 Petitions
Accused Products
Abstract
A full displacement retractable syringe has a front mounted retraction mechanism and a plunger with a sliding seal and a retraction opening with a sliding stopper. A needle holder is held in place with a holding ring which seals the front part of the barrel from fluid leakage and forms the bottom of a variable chamber in the barrel. The top of the variable chamber is formed by the nose of the plunger with its sliding plunger seal and stopper. Substantially all of the fluid contained in the variable chamber is expelled through a needle when the plunger is depressed to bring the upper and lower boundaries of the fluid chamber together. Because the plunger seal is restrained from forward movement by a stop in the barrel, the nose of the plunger slides through the plunger seal to operate the retraction mechanism. When the holding ring and stopper are gradually removed an instable state is reached whereby a spring compressed under the head of the needle holder overcomes remaining holding forces and the needle holder and needle together with the stopper are forced rearwardly into the retraction cavity. The syringe can be reused only until the plunger is fully depressed after the last injection. Coincident with the retraction action, the plunger enters the barrel to prevent reuse.
-
Citations
19 Claims
-
1. A full displacement syringe, comprising:
-
an elongated housing comprising a hollow barrel having a front end portion, and an inner surface; a plunger configured to reciprocate in the barrel, the plunger having a retraction cavity within and a tubular nose in front with a leading wall having a removably sealed opening into the retraction cavity; a retraction mechanism mounted in the front end portion of the barrel, the retraction mechanism comprising a needle and needle holder having a head, a biasing element tending to drive the needle holder rearwardly and a movable holding ring mounted on the head of the needle holder, said ring holding the retraction mechanism by contact with the inner surface of the barrel, wherein the retraction mechanism forms the bottom of a variable fluid chamber in the barrel; a plunger seal forcibly slideably mounted near the front of the tubular nose of the plunger, said plunger seal being movable with the plunger in sliding contact with the inner surface of the barrel during fluid transfer operations; a plunger seal restraint located on the barrel wall to restrain the plunger seal from forward movement after it has reached the bottom of the variable chamber without said restraint preventing the plunger nose from sliding forward through the plunger seal to operate the retraction mechanism; whereby depression of the plunger to place the plunger seal at the bottom of the variable fluid chamber causes substantially full displacement of fluid from the barrel and further forward movement of the plunger causes the leading wall of the tubular nose of the plunger to operate the retraction mechanism by moving through the plunger seal to push the movable holding ring off the head of the needle holder, thereby initiating retraction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A full displacement syringe, comprising:
-
a syringe barrel having a wall defining a hollow interior surface and a front end portion; a plunger having a nose portion in front and a forcibly slidable plunger seal on the nose that moves with the plunger during normal syringe operations; a retraction mechanism having a spring mounted in the front part of the barrel, characterized by a needle holder having a movable holding ring member which traverses the barrel to the interior surface thereof to hold the retraction mechanism in place above the compressed spring located under the needle holder, said retraction mechanism forming the bottom of a variable fluid chamber in the barrel; a stop in the barrel which prevents forward movement of the plunger seal after it reaches the bottom of the variable fluid chamber thereby expelling substantially all fluid; said nose portion of the plunger having a leading wall portion forming a removably sealed opening large enough to receive the head of the needle holder while pressing against said movable holding ring member; whereby said plunger can move forward relative to said plunger seal after the plunger seal is at the bottom of the variable fluid chamber thereby causing said leading wall to dislodge and move said holding ring member off the head of the needle holder to initiate retraction. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
-
18. A full displacement retractable syringe, comprising:
-
an elongated syringe housing having a tubular wall, comprising a nose portion in front, an intermediate body section and an opening behind for receiving a plunger; a retraction mechanism mounted in the nose portion of the housing, the retraction mechanism comprising a needle and a rearwardly biased needle holder having a head portion and a holding ring releaseably mounted on the head portion and extending in sealing contact with the wall of the housing which together form the lower boundary of a variable fluid chamber in the housing; an elongated tubular plunger having a wall configured in front to form a protruding tip, the protruding tip having a bearing surface for a slidable plunger seal to be mounted thereon and an opening therein leading into the plunger, the opening being occupied by a stopper slidingly mounted in said opening; a plunger seal mounted on a front part of the bearing surface on the protruding tip, for movement with the plunger in sliding sealing contact with the housing, the plunger seal being slidable rearwardly along said bearing surface in response to force applied to the seal in excess of operational force or pressure force generated in the course of drawing and expelling fluid to or from said fluid chamber, wherein said tip, said stopper and said seal define the upper boundary of a variable fluid chamber in the housing; whereby nearly all fluid previously drawn into the variable fluid chamber is expelled through the needle when the upper and lower boundaries of the fluid chamber are brought together by depression of the plunger to a first position, and retraction occurs by movement of the plunger forward beyond the first position whereby the plunger seal is constrained against forward movement by a restriction causing the plunger seal to slide rearwardly relative to the protruding tip while the protruding tip engages and pushes the holding ring from the head of the needle holder to free the needle holder and allow it to retract into the plunger through the opening in said tip.
-
-
19. A full displacement retractable syringe, comprising:
-
an elongated tubular housing comprising a barrel having a wall with an inner surface defining a hollow space comprising a fluid chamber and an opening behind; a plunger having a tubular wall configured to define a protruding tip portion in front having a tip and a hollow interior, the hollow interior comprising a retraction cavity, the plunger having a thumb cap behind and being adapted for reciprocating movement within said housing; an opening in the tip portion of the plunger leading into the retraction cavity and slidingly sealed by a removable stopper; a plunger seal movably mounted in a forward position near the front of the protruding tip portion of the plunger, for slidable movement relative to the plunger from the forward position on said tip portion to a rearward position on said tip portion behind said forward position, said plunger seal extending laterally in sliding sealed contact with the inner wall of said housing to form a seal on the plunger for drawing or expelling fluid from the housing; a retraction mechanism mounted in the front of the housing, the retraction mechanism having a needle mounted in an inwardly biased needle holder having a head portion fitted with a holding ring releaseably mounted thereon, the ring extending laterally in sealing contact with the wall of the housing; the protruding tip, stopper and plunger seal comprising the upper boundary of a variable fluid chamber in the housing; the needle holder head and holding ring comprising the lower boundary of the variable fluid chamber in the housing; whereby fluid is fully displaced from the variable chamber when the upper boundary and lower boundary are brought together by forward movement of the plunger to a first position of the plunger; retraction occurring by further forward movement of the plunger to a second position beyond said first position whereby the holding ring is pushed forwardly relative to the head of the needle holder by the end of the protruding tip while the needle holder and plunger seal are held stationary by the housing as the plunger moves forward until the needle holder comes free from the holding ring to retract along with the stopper into the retraction cavity of the plunger.
-
Specification