Patent ID: 8038694

Claim:
A lancet instrument adapted to be detachably fitted to a lancing apparatus when used, comprising: a lancet defined by a lancet body with a sharp lancet tip at its tip and a lancet hub fixed to said lancet body so that the lancet tip is exposed, said lancet hub including an elastic deformation part that is elastically deformable so that the distance of said elastic deformation part from said lancet body can be changed; a ring-like member separate and distinct from said lancet, said ring-like member being fitted to an outer periphery of said elastic deformation part of said lancet hub so that a distal-most end of the ring-like member is positioned proximally of a distal-most end of the elastic deformation part of said lancet hub, the ring-like member being releasable from said elastic deformation part of said lancet hub in a tip direction by changing the distance between said elastic deformation part of said lancet hub and said lancet body, wherein, upon release of said ring like member from said elastic deformation part, said elastic deformation part expands to a radially enlarged state in order to limit movement of the lancet hub in the tip direction; and a casing storing said lancet so as to be movable in the longitudinal direction, the casing having a ring-like member contact part formed in an inner peripheral part of the casing so that the ring-like member is brought into contact with the ring-like member contact part and is blocked to move in the tip direction, and the casing possessing a tip opening through which said lancet tip can be projected; wherein the projection of said lancet tip through said tip opening of said casing is blocked by moving said ring-like member released from said lancet hub in the tip direction between the distal-most end of said elastic deformation part of said lancet hub and said ring-like member contact part to restrict the movement of said lancet; wherein an inner periphery of said ring-like member has a tapered shape such that an inside diameter of the ring-like member gradually increases in the tip direction; and wherein an outer periphery of a fitting part of said elastic deformation part, to which said ring-like member is fitted, has a tapered shape such that an outside diameter of the fitting part gradually increases in the tip direction.