| 摘要 |
<p>1. A safety syringe having a retractable needle facility incorporated therein is disclosed. The syringe comprises a barrel and plunger and needle assembly, the plunger having gasket means on its end to seal between the plunger and barrel to form a reservoir in known fashion. The gasket means is compressible under an additional load. In a first downward stroke of the plunger under normal load, without the additional load applied, the plunger does not engage the needle assembly, so that fluid is then drawn into the barrel of the syringe by a first upstroke. In a second down stroke after the injection has been completed, an additional load is applied to the plunger to compress the gasket so that the end of the plunger travels further to engage the needle assembly for subsequent retraction of the needle assembly on a second upstroke. By this means the needle is thus caused to retract mto the barrel of the synnge upon completion of injection, the compressible gasket being provided with internal ribs so that it is self supporting under normal load.</p> |
