| 摘要 |
A disposable syringe includes a needle assembly having a needle seat retained in a barrel by a grip member to fix a needle cannula, a tubular plunger movable in the barrel toward the needle seat during an injection course, and a coupling member having a retained shank in frictional engagement with the plunger, and an anchored portion disposed outwardly of the plunger to engage a rear anchoring portion of the needle seat when the coupling member is moved forwardly. When the plunger is moved further forward to cause the plunger to move relative to the coupling member, the retained shank is released to enable the needle assembly to retract into the plunger by means of a biasing member. A guiding sleeve is sleeved on the needle seat, and can be forced to extend between the needle seat and the grip member so as to decrease the frictional force therebetween for ensuring successful retraction of the needle assembly.
|
