Patent ID: 7469475

Claim:
A safe knife sheath comprising a sheath body and a blade support; the blade support is mounted inside the sheath body and movable in a sliding motion; a front part of the sheath body has a push button; a lower part of the push button is connected to a positioning element; a lower part of the blade support has a positioning groove corresponding to the positioning element; a positioning channel is disposed near an upper inner surface of the sheath body; on a top near an inner end of the blade support a positioning lobe corresponding to the positioning channel is disposed so that the blade support is prevented from being pulled out from the knife sheath when the positioning lobe reaches an outer end of the positioning channel; a top of the push button is connected to one end of a first reset spring, and the other end of the first reset spring is fixed in the upper end of the sheath body; in the back of the blade support a trapezoidal piece is disposed; the trapezoidal piece is in trapezoid shape with a bottom side, a top side, a first slanted side and a second slanted side; the bottom side which is parallel to the top side is shorter than the top side; the first slanted side is disposed further away from an inner end of the blade support; the second slanted side is disposed nearer to the inner end of the blade support; on the lower side of the trapezoidal piece a second reset spring is disposed; the second reset spring is a torsion spring with a first leg and a second leg; the first leg is fixed in a lower end of the sheath body; the second leg of the second reset spring is in an inverted V shape skewed towards an outer end of the sheath body so that the outer end of the second leg bends downwards; and the second leg is fixed on an inner side of the sheath body; the second slanted side of the trapezoidal piece substantially abuts against the outer end of the second leg when the blade support is at a position when the positioning lobe reaches the outer end of the positioning channel.