Medical needle safety device

A safety device for a medical needle having a mount end and a sharp tip, which device comprises:

• a tubular support directly or indirectly associated with the needle mount end;
• a tubular protective shield disposed co-axially on the support for sliding movement with respect thereto from a set position where a part of the length of the needle back from its tip is exposed, to a fully retracted position and then to a locked position where the shield covers the needle to afford protection thereto, the shield and support being restrained against significant relative rotational movement;
• a locking member rotationally mounted on the support within the shield, there being a cam profile on one of the locking member and support and a cam follower on the other of the locking member and support whereby forward axial movement of the support with respect to the locking member causes the locking member to rotate relative to the support;
• a guide extending generally axially of the shield and defining a shoulder towards the rearward end thereof;
• an abutment on the locking member engageable with the guide and receivable behind said shoulder when the shield is in its locked position;
• resilient means for urging the locking member rearwardly, said resilient means acting between the locking member and the shield thereby to urge the locking member rearwardly with respect to the shield;
• and
• a stop defined by the shield and positioned for engagement by the abutment to hold the locking member against rearward movement under the action of said resilient means when the shield is in its set position;
• whereby rearward movement of the shield from its set position relative to the support causes interaction between the cam profile and cam follower to turn the locking member with respect to the support thereby rotationally shifting the locking member from said stop, and on subsequent forward movement of the shield to its locked position under the action of said resilient means, the interaction between the cam profile and cam follower causes the locking member to turn further to allow engagement of the abutment with the shoulder of the shield, thereby preventing subsequent rearward movement of the shield from its locked position.