Abstract: A safety structure for covering a syringe needle includes a safety sleeve and a hub provided with a sideward projection. The safety sleeve is fitted around the hub and provided with an axial sliding slot, a locating slot laterally extended from the sliding slot, a locating hole located at a bottom of the locating slot behind a locating section, and two opposing protrusions located in the locating slot between the sliding slot and the locating section. When the projection is abutted on a bottom of the sliding slot, the needle is exposed from the safety sleeve; when the projection is reversibly located behind the two opposing protrusions, the needle is temporarily enclosed in the safety sleeve and protected against contamination; and when the projection is moved behind the locating section into the locating hole, the needle is permanently enclosed in the safety sleeve without the risk of stabbing a user.

Abstract: A safety syringe with a needle sleeve is provided. The needle sleeve is put around a cap of the syringe with a shoulder portion inside the needle sleeve abutting against a rear flange of the cap, such that the cap, a hub tightly fitted in the cap, and the needle sleeve together form a needle sleeve assembly, which allows the hub to temporarily locate closely before a neck portion of a barrel of the syringe, so that the syringe may be sterilized under high temperature without stress deformation and thermal deformation. When the cap is depressed, the hub and a cannula held thereto are caused to move backward and be stably retained to the neck portion of the barrel in an airtight relation. And when the cap is pulled forward again, it brings the needle sleeve to together separate from the hub to expose the cannula for injection.

Abstract: A safety syringe with a needle sleeve lock is provided. The needle sleeve lock is put around a cap of the syringe with radially outward projected second stoppers at rear end of the cap located between a shoulder portion and two radially inward projected first stoppers inside the needle sleeve lock, such that the cap, a hub tightly fitted in the cap, and the needle sleeve lock together form a needle sleeve lock assembly, which allows the hub to temporarily locate closely before a neck portion of a barrel of the syringe, so that the syringe may be sterilized under high temperature without stress deformation and thermal deformation. When the cap is turned to separate the second stoppers on the cap from the first shoulder portion and the first stoppers of the needle sleeve lock and then depressed, the hub and a cannula held thereto are caused to move backward and be stably retained to the neck portion of the barrel in an airtight relation.

Abstract: A safety syringe ensuring stable and airtight connection of a hub to a barrel of the syringe is provided. A rear portion of the hub is tightly fitted in a neck portion at a front end of the barrel, such that the hub is prevented from moving out of the barrel via the neck portion. A first airtight contact line is formed at joint of two shoulder portions separately formed on the hub and the neck portion, and a second airtight contact line is formed at a position within a contact surface between the hub and the neck portion, so that the hub is stably and air-tightly connected to the barrel. A plunger is disposed in the barrel to push medical liquid in the barrel into the hub and a cannula fixed to the hub for injection purpose. An engaging cone having a slit is forward projected from a front end of the plunger to engage into receiving holes formed on the hub when the plunger is fully push forward.

Abstract: A safety syringe that is characterized by that a plunger thereof has an elastic stopper fitted around a neck portion of the plunger near a front end thereof. When the plunger is fully pushed forward in a barrel of the syringe, the stopper slightly deforms to allow the plunger to move forward a little further, so that all medical liquid in the barrel is injected into a patient's body. The safety syringe is also characterized by that an elastic catch hook is provided at the front end of the plunger and a catch rib is provided around a rear inner end of a locking tip that is fitted to a front end of the barrel for a needle to connect thereto. When the plunger is further pushed forward in the barrel, the catch hook is moved beyond the catch rib and retained in the locking tip by the catch rib. Whereby, simply pulling the plunger backward could directly pull the locking tip and a used needle backward into the barrel to avoid injuring others.