Retractable sheath for hypodermic needle
First Claim
1. A retractable sheath assembly for a hypodermic needle, comprising:
- a barrel adapted to be attached to a syringe of a hypodermic needle with the needle projecting axially from the barrel;
an elongate, cylindrical sheath telescopically mounted relative to the barrel and slidably moveable from an extended position to cover the needle to a retracted position uncovering the needle;
the sheath having an inner end portion and the barrel having a distal end portion;
a cam formed on one of said barrel distal end portion and said sheath inner end portion;
a cam follower formed on the other of said sheath inner end portion and said barrel distal end portion, the cam follower being adapted to engage the cam; and
the cam having a first segment unblocking the cam follower and permitting retraction of the sheath to uncover the needle, a second segment blocking the cam follower and preventing retraction of the sheath to uncover the needle, and an intermediate segment for moving the cam follower between the first and second segments after retraction of the sheath to uncover the needle.
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Accused Products
Abstract
A retractable sheath for a hypodermic needle is shown for preventing accidental needle pricks. The sheath automatically extends to cover the needle and retracts to expose the needle without having to touch the sheath or activate any locking or release mechanisms. A barrel is mounted on the hypodermic needle or syringe with the needle projecting axially therefrom. A telescoping sheath is mounted in or over the barrel to extend and retract respectively to cover and uncover the needle. A cam and cam follower co-operatively formed in the barrel and sheath prevents the sheath from retracting by an accidental force on the sheath but allows the sheath to be cocked, so that a second deliberate force on the sheath allows the sheath to retract allowing the needle to be inserted into the skin. The cam has a first segment which allows the cam follower to slide longitudinally permitting the sheath to retract, a second segment which blocks the cam follower preventing retraction of the sheath, and an intermediate segment that moves the cam follower from the blocked position to the ready or cocked position, so that a subsequent force on the sheath allows it to retract automatically and then return to the blocked position.
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Citations
15 Claims
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1. A retractable sheath assembly for a hypodermic needle, comprising:
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a barrel adapted to be attached to a syringe of a hypodermic needle with the needle projecting axially from the barrel; an elongate, cylindrical sheath telescopically mounted relative to the barrel and slidably moveable from an extended position to cover the needle to a retracted position uncovering the needle; the sheath having an inner end portion and the barrel having a distal end portion; a cam formed on one of said barrel distal end portion and said sheath inner end portion; a cam follower formed on the other of said sheath inner end portion and said barrel distal end portion, the cam follower being adapted to engage the cam; and the cam having a first segment unblocking the cam follower and permitting retraction of the sheath to uncover the needle, a second segment blocking the cam follower and preventing retraction of the sheath to uncover the needle, and an intermediate segment for moving the cam follower between the first and second segments after retraction of the sheath to uncover the needle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification