Patent ID: 8439941

Claim:
A disposable lancing device comprising: a housing; a spring member; a lancet having a puncture member provided at a distal end thereof, the lancet being housed in the housing and urged by the spring member such that the puncture member is configured to extend out from the housing and carry out a puncturing operation; a locking ring disposed within the housing such that the lancet is allowed to displace in an extension direction through the locking ring; a locking protrusion extending from the lancet and adapted to be engaged by the locking ring so as to hold the lancet in a puncture-ready position located deep in the housing with the spring member being compressed; an operating member adapted to carry out the puncturing operation by rotating the locking ring so as to disengage the locking protrusion from the locking ring and displace the lancet in the extension direction by means of the spring member; and a reuse-preventing protrusion provided on the lancet and configured to prevent the locking protrusion from being re-engaged by the locking ring such that with the locking ring located at a rotational position representing that the locking protrusion has been disengaged and the puncturing operation of the lancet has been carried out, as the lancet is pushed and displaced deep into the housing the reuse-preventing protrusion comes into abutment against the locking ring so as to limit deep displacement of the lancet relative to the locking ring, wherein the locking protrusion and the reuse-preventing protrusion are formed on an outside peripheral face of the lancet, while being spaced away from each other in a circumferential direction, the locking protrusion is formed at a location axially rearward by a prescribed dimension from the reuse-preventing protrusion, the locking ring is attached rotatably about the outside peripheral face of the lancet, and has a mating portion of an inner flange shape, the mating portion includes a first passage slot through which the reuse-preventing protrusion is able to pass, and a second passage slot through which the locking protrusion is able to pass, and a relative position in the circumferential direction of the reuse-preventing protrusion and the locking protrusion of the lancet differs from the relative position in the circumferential direction of the first passage slot and the second passage slot of the locking ring.