Dental cartridge assembly auto-injector with protective needle cover

An automatic injection device pre-loaded with a charge of medicament for automatically self-administering said medicament upon actuation thereof, comprising:

• a generally tubular outer body having a rearward end and a forward end;
• a medicament cartridge assembly carried within said outer body, said cartridge assembly including
• i) a glass container having a rearward portion thereof with a predetermined inner diameter and a forward portion thereof with an inner diameter smaller than said predetermined inner diameter,
• ii) a charge of medicament disposed within said glass container,
• iii) a plunger member rearwardly confining said medicament within said glass container and being slidably movable forwardly within said glass container,
• iv) a seal for sealing the forward portion of said glass container having said smaller inner diameter and for forwardly confining said medicament within said glass container,
• a needle disposed forwardly of said cartridge within said outer body, said needle having a forward end and a rearward end, said rearward end of said needle being disposed proximate said seal and being separated from said medicament by said seal when said injection device is in a storage condition, at least one of said seal and said needle being movable with respect to the other so that said rearward end of the needle pierces said seal to establish communication with said medicament during an injection operation, and said needle being movable with respect to said body so that said needle projects outwardly from the forward end of said body during said injection operation,
• a rigid needle cover member normally maintained in an inoperative position wherein the needle cover is retracted with respect to said body so that the forward end of said needle is permitted to extend forwardly beyond said needle cover member and being movable relative to said body to a protective position wherein the needle cover member extends forwardly beyond the forward end of said needle with the needle projecting outwardly from the forward end of said body, said needle cover being movable from said inoperative position to said protective position as a result of said injection operation;
• a locking arrangement for locking said needle cover in said protective position after said injection operation so as to maintain said cover member in said protective position extending forwardly beyond the forward end of said needle;
• and
• a releasable drive assembly comprising a releasable spring and a collet member, said releasable spring being releasable in response to a predetermined actuating procedure to drive said collet member forwardly within said outer body and thereby enable
• i) at least one of said seal and said needle to move with respect to the other so that said rearward end of said needle pierces said seal to establish communication with said medicament,
• ii) the needle to move with respect to the body so that the needle projects outwardly from the forward end of the body, and
• iii) the needle cover to move relative to said body from the inoperative position to the protective position so that the needle cover member extends beyond the forward end of the needle with the needle projecting outwardly from the forward end of the body.