Abstract: A first embodiment of an automatic injector employs less material and fewer parts by eliminating an outer housing required in earlier automatic injectors. In a second embodiment, a manually operated sharps protector is provided. In a third embodiment, the sharps protector is deployed by a spring positioned internally of the sharps protector. In a fourth embodiment, the sharps protector is deployed by a spring positioned externally of the sharps protector. In all embodiments, removal of a safety cap enables a user to press on an outer gun sleeve that displaces in an axial direction and releases the trailing end of a spring holder so that a compressed spring that bears against the spring holder unloads and drives a piston that displaces a cannula into the tissue of a user, followed by a liquid medicament injection through the cannula.

Abstract: An additive adapter for use in conjunction with an injector wherein the injector includes a cylindrical body having a rearward open end and a forward end necked inwardly to form an annular lip. The forward end having a central opening of reduced diameter which is closed off by a sealing diaphragm. A plunger is sealingly and slidably fitted in the rearward portion of the body to form a medicament chamber between the sealing means and the plunger. A needle hub is affixed to the annular lip and carries a needle which is in fluid communication with the medicament chamber upon the opening of the sealing diaphragm. The additive adapter comprises a main body portion including a cylindrical skirt portion extending from the rearward end of the cylindrical sleeve. The skirt is sized to snugly engage and fit over the forward portion of the injector's cylindrical body. A cylindrical shield having a diameter larger than the cylindrical sleeve extends from the forward end thereof.

Abstract: A hypodermic injection device comprising a cartridge holder having a cylindrical body open at one end and closed at the other end, the closed end being provided with an aperture, a cartridge with the holder, the cartridge including an ampoule having a cylindrical sleeve open at one end and having a necked portion at the other end to receive a hub mounting a cannula, the cannula facing the apertured end of the cylindrical body, a piston slidably carried within the sleeve adjacent the open end thereof to define a medicament chamber between the piston and cannula, fluid medicament in the medicament chamber, the piston having a concave face on the side forming one end of the medicament chamber, a spring power assembly adjacent the open end of the ampoule sleeve for moving the cartridge forward and for injecting the fluid medicament, spacer means positionable between the outer face of the piston and the adjacent spring power means to vary the position of the piston within the ampoule sleeve and thereby control the