| 摘要 |
A self retracting hypodermic syringe resembles and is used like a standard syringe except that it is automatically disabled at the instant that the injection is completed. During the injection, the plunger is pressed into the syringe body. When the plunger reaches the front of the syringe an actuating element attaches to the needle assembly and unlocks it from the syringe body. At the same time a spring is unlatched driving the injection needle into the body of the syringe. In order to actuate the spring the plunger must be driven beyond a detent provided for tactile identification of the limit of travel for the purpose of filling the syringe. After use, the needle cannot be retrieved and the syringe is not reusable. The fast withdrawal of the needle from the patient results in much less pain.
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