| CPC A61M 5/322 (2013.01) | 27 Claims |
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1. An injection device comprising:
an injection device body;
a needle shroud retractable into the injection device body;
a control spring coupled to the needle shroud and biased to cause the needle shroud to be at least partially extended from the injection device body in an initial position; and
a hold detent mechanism coupled to at least the needle shroud, wherein the hold detent mechanism is configured to:
activate, when the needle shroud is retracted from the initial position into the injection device body to a hold position, to create a hold detent force opposite a control spring force caused by compression of the control spring during said retraction of needle shroud to said hold position; and
deactivate, when the needle shroud is extracted from the hold position subsequent to the retraction, to release the hold detent force and enable the needle shroud to extend from the injection device body to substantially the initial position; and
a collar within the injection device body and rotatably configured for guiding said needle shroud between the initial position and the hold position;
a plunger and biasing means for biasing the plunger towards a distal end of the injection device,
wherein when the needle shroud is in the initial position, the plunger is retained by a combination of a rear casing of the injection device and the collar preventing the biasing means from displacing the plunger in a distal direction, and on activation of the injection device, the collar rotates and guides the needle shroud to the holding position and causing, when the needle shroud is in the holding position, the biasing means to move the plunger in the distal direction of the injection device.
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