| 摘要 |
A disposable dental safety-syringe comprises a barrel 10 to receive a cartridge 24 of injectable fluid, said barrel having a forward end for connection to a needle 38 and a rearward end for receiving a plunger 13, and a sleeve 22 mounted relative to the barrel and slidable between three locking positions; wherein the sleeve either extends beyond the forward end of the barrel (Fig 2c), sheathing the needle, or the sleeve is rearward of the forward end of the barrel, exposing the needle (Fig 2b). The sleeve comprises a lock 25 in the form of circumferentially offset cooperable configurations (26, Fig 4, 27, Fig 5c) interengageable by rotation to move between a release position (where axial movement of the sleeve relative to the barrel is possible) and a temporary lock position (where axial movement of the sleeve relative to the barrel is restricted but rotation back to the release position is possible) and to a permanent lock position (wherein both axial movement and rotation of the sleeve are restricted). The circumferentially offset cooperable configurations may comprise a number of inwardly extending formations provided in the form of multiple ramp surfaces and stop surfaces. |
