US Patent 7387616 Safe medical needle apparatus

A safe medical needle apparatus, including a needle duct having a needle head, a needle seat, in which the needle tail is installed; a safe protecting shell and a biasing part through which the needle duct can pass; A protuberant stop portion, which is provided on the outer surface of the needle duct near the needle head, and the maximum size of cross section thereof is larger than the outer diameter of the remainder of the needle duct; the safe protecting shell there inside includes sequentially a biasing part cavity near the outlet, a protecting cavity, the across section of which is smaller than the biasing part cavity, a stop portion of the protecting shell and a needle seat cavity near the inlet of the needle duct and matching the needle seat; the size of the stop portion of the protecting shell is smaller than the maximum size of the stop portion of the needle duct, making the needle duct be movable therein but the stop portion of the needle duct be locked thereby, wherein a side of the biasing part cavity having a releasing port. Said biasing part is elastic and includes a through hole, under action of a external force the biasing part is contained in the biasing part cavity and is so biased that the needle duct can pass the through hole, and if the external force is removed, the through hole displaces and staggers with the needle duct under the action of the elasticity.