| 摘要 |
<p>A syringe has a barrel (1) housing a plunger (8) linked to a piston incorporating a seal (7) by a coupling member (9). A flange (12) on the coupling member (9) limits the extent of movement of the plunger and piston assembly, in association with latches (16). As the plunger (8) is operated through a sequence of expelling air from the syringe, to draw in liquid into the syringe and then to eject the liquid out again through a needle connected to an outlet (5), camways (11) at the ends of the coupling member (9) operate with projecting keys in such a way that the coupling member (9) is caused to rotate in stages. Then after the plunger is withdrawn again (after ejection of the liquid) the projecting keys (10) on the part associated with the piston seal (7) will become detached from the relevant keyways (11) so that the syringe cannot be used a second time.</p> |
