Automatic injector
An automatic injector dispenses a predetermined dose of medicament without a user having to manually force the needle into an injection site. The automatic injector includes a needle cover having a locked retracted position with respect to the injector housing prior to a medicament dispensing operation. The needle cover is operative to engage an injection site prior to a medicament dispensing operation.
1. An automatic injector comprising:
a housing;
a cartridge container disposed within the housing;
a cartridge received in the cartridge container, the cartridge containing a medicament and including a needle assemble to allow the medicament to be dispensed there through, the needle assembly comprising a needle;
an actuation assembly comprising a power pack outer body, power pack inner body comprising a hollow interior, a collet received within the hollow interior of the power pack inner body, and a power pack spring assembly providing a stored energy source, the actuation assembly disposed within the housing, the actuation assembly operative to drive the medicament through the needle during a medicament dispensing operation in response to release of stored energy from the stored energy source;
a needle cover received in the housing, the needle cover having an opening operative to receive there through at least part of the cartridge container, the needle cover having a locked retracted position with respect to the housing prior to a medicament dispensing operation, the needle cover having a surface operative to contact an injection site prior to a medicament dispensing operation; and
a needle cover spring compressed between said surface of the needle cover and the cartridge container, the needle cover spring comprising a maximum load less than force required to release stored energy from the stored energy source of the actuation assembly to drive the medicament through the needle.
2. The automatic injector of claim 1 further comprising a locking mechanism operative to prevent movement of the needle cover outward from the housing when the needle cover is in the locked retracted position, the locking mechanism comprising a locking tooth that engages the needle cover when the needle cover is in the locked retracted position.
3. The automatic injector of claim 1 wherein the needle cover has a locked extended position with respect to the housing after the medicament dispensing operation.
4. The automatic injector of claim 3 further comprising a locking mechanism operative to prevent movement of the needle cover into the housing when the needle cover is in the locked extended position, the locking mechanism comprising a locking arm connected to the cartridge container that engages an outer edge of the needle cover when the needle cover is in the locked extended position.
5. The automatic injector of claim 1 wherein the needle cover surface operative to contact an injection site is an enclosed front end surface of the needle cover, the front end surface having an opening sized to permit passage of only the needle there through.
6. The automatic injector of claim 1 wherein the needle cover extends beyond the housing in the locked retracted position.
7. The automatic injector of claim 1 wherein the needle cover is received in the housing between the housing and the cartridge container.
8. The automatic injector of claim 1 wherein no part of the housing is operative to contact an injection site during a medicament dispensing operation.
9. The automatic injector of claim 1 wherein the housing has an oval-shaped lateral cross section.
10. The automatic injector of claim 1 wherein stored energy released from the stored energy source during a medicament dispensing operation is not transferred to the needle cover.
11. The automatic injector of claim 1 wherein residual stored energy released from the stored energy source is contained by the cartridge container, the cartridge, the housing, and the actuation assembly to prevent kickback of the automatic injector during a medicament dispensing operation.
12. The automatic injector of claim 1 wherein the cartridge container has a closed front end having an opening therein sized to receive only the needle there through during a medicament dispensing operation.
13. The automatic injector of claim 1 wherein the medicament comprises epinephrine or diazepam.
14. The automatic injector of claim 1 wherein the needle is encased in a sheath and wherein the power pack spring assembly provides an injection force sufficient to advance the cartridge within the cartridge container to drive the needle such that the needle pierces the sheath to permit injection of the medicament.
15. The automatic injector of claim 1 wherein the force required to release stored energy from the stored energy source of the actuation assembly is a force required to release the collet from the power pack inner body when the automatic injector is pressed against an injection surface.