US Patent 9339611 Retracting sheath detachable safety needle with moving spring

A passive safety needle device is disclosed having a housing, a needle hub, a needle cannula, a retractable sheath, a spring to bias the retractable sheath in a distal direction to cover the distal end of the needle cannula, a radial protrusion to cause the spring to move from the proximal spring position to the distal spring position, and a catch to secure the distal end of the spring to the distal end of the housing. The spring may bias the retractable sheath in a distal direction to cover the distal end of the needle cannula. The radial protrusion causes the spring to move from a proximal spring position to the distal spring position towards the catch located at the distal end of the housing.