Patent ID: 8568367

Claim:
An automatic injection device containing a pre-loaded charge of medicament for automatically self-administering the medicament upon actuation thereof, the device comprising: a housing; a medicament chamber disposed in the housing, the medicament chamber including a first compartment containing a first medicament portion, and a second compartment containing a second medicament portion to be mixed with the first medicament portion; a seal structure between the first compartment and the second compartment, the seal structure being initially in a sealing condition that maintains the first compartment separate from the second compartment, the seal structure being converted to a mixing condition as a result of activation of the device; a needle assembly that dispenses the medicament charge from the medicament chamber; and an activation assembly disposed in the housing and including a stored energy source, wherein activation of the activation assembly releases the stored energy from the stored energy source, causing the seal structure to be converted from the sealing condition to the mixing condition, and thereby causing or allowing the first and second medicament portions to be mixed and forced through the needle assembly; wherein the needle assembly comprises a needle and a needle support for mounting the needle to the medicament chamber, the needle support defining a needle assembly chamber having a rearward opening in fluid communication with the medicament chamber, the rearward opening has the smallest diameter opening through which fluid flows from the medicament chamber to the rearward opening, the needle assembly chamber having an inner surface tapering radially inward as it extends axially forward towards a rearward end of the needle, the needle support having a passageway connecting the needle assembly chamber to the needle and having a diameter narrower than the outside diameter of the needle, the inner surface of the needle assembly chamber having a diameter at the connection to the passageway that equals the diameter of the passageway.