US Patent 7314464 Pen needle and safety system

A safety shield system having a needle assembly with a safety shield movable from a first position enclosing an end of a needle cannula, to a second position exposing the end of the needle cannula for injection, to a third position lockingly enclosing the end of a needle cannula. The safety shield system permits retraction of the safety shield during use, but extends the shield enclosing the needle cannula in a locked position following use. The safety shield system also has a cap for receiving the needle assembly and lockingly enclosing another end of the needle cannula. Thus, both ends of a double-ended needle cannula are lockingly enclosed following use of the needle assembly of the inventive safety shield system.