| 主权项 |
1. A liquid injection instrument comprising:
an internal structural body having
a cylindrical body that has a cylindrical shape and has an inner cavity part in which a liquid is housed,a hollow needle that is disposed at a distal part of the cylindrical body, communicates with the cylindrical body, and has a sharp needle tip at a distal end,a gasket that is slidable in the cylindrical body, anda plunger that is coupled to the gasket and carries out a movement operation of the gasket along an axial direction of the cylindrical body; and a protector that is disposed on an outer circumferential side of the internal structural body movably relative to the internal structural body along the axial direction, and has a tubular shape and a distal opening; wherein the protector is capable of taking
a first state in which the liquid still remains housed in the cylindrical body and the distal opening of the protector is located closer to a distal side than the needle tip,a second state in which the needle tip protrudes from the distal opening of the protector due to a movement of the protector toward a proximal side and the gasket is movable in a distal direction,a third state in which the liquid is discharged via the hollow needle due to a movement of the gasket in the distal direction, anda fourth state in which the distal opening of the protector is located closer to the distal side than the needle tip again, wherein the protector has an outside engagement piece that is provided in a tube wall of the protector and is elastically deformed, the cylindrical body has an inside engagement piece that is provided at a proximal part of the cylindrical body, engages with the outside engagement piece in the fourth state, and is elastically deformed, and the plunger has a pressing portion that presses and deforms the inside engagement piece outward in the fourth state, wherein in the third state, the pressing portion of the plunger moved in the distal direction presses and expands the outside engagement piece outward collectively with the inside engagement piece, and wherein in the fourth state, the outside engagement piece returns to an original shape, and the inside engagement piece remains pressed and deformed outward by the pressing portion to engage directly with the outside engagement piece, so that the movement of the protector in a proximal direction is prohibited by the engagement. |
