GB1263355A — Hypodermic injection device

USPTO Abstract

1,263,355. Hypodermic injection devices. P H I L I P S ' GLOEILAMPENFABRIEKEN N.V. 3 July, 1969 [9 Aug., 1968], No. 33615/ 69. Heading A5R. A hypodermic injection device comprises a cartridge holder closed off at one end containing a cartridge 106 consisting of an ampoule 136 with a cannula 150 attached at one end, and a piston 148 at the other, the cannula end of the cartridge being sealed by a frictional engagement of the periphery of the piston end of the ampoule with the cartridge holder wall. The device is operated by a spring-loaded firing mechanism consisting of a plunger 162 which has a cylindrical head 164 acting on the piston 148 and a cylindrical body having springy arms extending backwards longitudinally with detent heads 186 at their ends which engage behind an end wall 122 of an inner sleeve 101 when the firing mechanism is cocked. The plunger is biassed towards the piston by a coil spring 138 and is released by sliding down an outer sleeve 192, which in its end wall 194 has a frustoconical cam surface 198 which acts on the detents 186 to push them axially inwards to enable them to pass through hole 120 in the end wall 122. The frictional engagement around the cartridge may be an annular bead 160, Fig. 7, extending around the inner surface of holder sleeve 104, or the outer end of the cartridge may be flared (92 Fig. 4 not shown). The closed end of the cartridge holder has a cannula-puncturable stopper 158, and the cannula end of the ampoule 136 is sealed by a diaphragm 152 (or 72, Fig. 1) which is rupturable by fluid pressure, or by engaging the ampoule end of the cannula. The plunger head 164 may be provided with a plurality of circumferentially spaced, radially extending tabs 168 which initially engage both the end of the ampoule shell and its piston (Fig. 7). After firing, the tabs push the cartridge to the end of its holder, when their outer portions break off and the inner portions act on the piston as shown in Fig. 9, to expel the contents of the ampoule. A safety device is provided, in the form of a cap 142 with a safety pin 144 which extends between the spring arms 184 to prevent operation of the device before its removal.