| 摘要 |
PROBLEM TO BE SOLVED: To enable a needle head set to be drawn into an outer tube after use of a syringe to prevent a bite into a human body by forming grooves between a plurality of wing parts equipped on a lock head making the front end of the wing part smaller than the rear end and the cross section on the rear end of all of a plurality of wing parts larger than an engaging hole of a lock sheet. SOLUTION: A lock head 70 is disposed on the front end of a plunger 60. The lock head 70 is equipped with a plurality of wing parts 71 and a protruding pillar 73. Grooves 72 are formed between wing parts 71. The front ends of the wing parts 71 are made smaller than the rear ends and the cross section of the whole rear ends of the wing parts 71 is made larger than an engaging hole 51 of a lock sheet 50. When the plunger 60 is proceeded toward the front end of the outer tube to approach the front end, the wing parts 71 are pressed by the engaging hole 71 to contract and, when the lock head 70 passes through the engaging hole 51, the wing parts 71 recover the original dimensions so as not to be drawn outside the engaging hole 51. When the plunger is rearward drawn out, the needle head set 30 is drawn into a storage chamber together interlocking with the lock sheet 50. |
