US Patent 9751222 Lockback folding knife with safety mechanism

A lockback folding knife having a handle, a blade body pivotally connected in the handle, a constraint member pivotally connected with the handle and having an end abutted with the peripheral edge of the blade body when the blade body is completely stretched out of or received into the handle, a first elastic element having an end fastened in the handle and other end abutted with other end of the constraint member, a locking pin protruded on the constraint member, and a safety switch pivotally connected in the handle and having a locking groove formed thereon corresponding to the locking pin. The locking groove and pin are fastened together when the blade body is completely stretched out of or received into the handle, and the locking groove is escaped from being fastened with the locking pin when the safety switch is applied force.