PEN NEEDLE SHIELD

1 . A pen needle shield assembly comprising:

a hub fixed to a needle cannula; and

a movable shield surrounding the hub, the movable shield comprising:

an upper portion having an outer diameter;

a lower portion having an outer diameter greater than the outer diameter of the upper portion; and

a distal opening; wherein

the movable shield moves from a first position where the needle cannula is retracted in the movable shield prior to use, to a second position where the needle cannula is extended out of the movable shield through the distal opening for medication delivery and to a third position where the needle cannula is retracted in the movable shield and locked to prevent further use.

2 . The pen needle shield assembly of claim 1 , wherein:

the movable shield includes a cam mechanism having an upper track and a lower track;

the upper track of the cam mechanism is disposed in the upper portion; and

the lower track of the cam mechanism is disposed in the lower portion.

3 . The pen needle shield assembly of claim 2 , wherein

the lower track of the cam mechanism includes an intermediate section corresponding to the first position and a bottom section corresponding to the third position; and

the third position is proximal to the first position.

4 . The pen needle shield assembly of claim 2 , wherein the hub includes a knob that comprises a flexible flange that extends outwardly and is configured to engage the cam mechanism.

5 . The pen needle shield assembly of claim 4 , wherein the knob includes two knobs disposed 180 degrees from each other.

6 . The pen needle shield assembly of claim 4 , wherein

the cam mechanism includes an opening that extends through an outer wall of the movable shield; and

the knob extends into the slot of the cam mechanism.

7 . The pen needle shield assembly of claim 4 , wherein the knob engages the lower track in the first position, engages the upper track in the second position and engages the lower track in the third position.

8 . The pen needle shield assembly of claim 7 , wherein the knob in the first position and in the third position engage different portions of the lower track.

9 . The pen needle shield assembly of claim 1 , wherein the movable shield rotates when moving from the first position to the second position.

10 . The pen needle shield assembly of claim 9 , wherein the movable shield does not rotate when moving from the second position to the third position.

11 . The pen needle shield assembly of claim 1 , wherein the hub includes an activation stop that locks the movable shield in the third position.

12 . The pen needle shield assembly of claim 11 , wherein the activation stop includes two activation stops disposed 180 degrees from each other.

13 . The pen needle shield assembly of claim 11 , wherein the activation stop comprises a flexible flange that is elastically compressed in the first and second position and is released in the third position to extend outwardly and contact a proximal end of the movable shield.

14 . The pen needle shield assembly of claim 1 , further comprising a coil spring that is compressed during use of the pen needle shield assembly in the second position.

15 . The pen needle shield assembly of claim 14 , wherein the coil spring applies a force to keep the movable shield in the first position prior to use.

16 . The pen needle shield assembly of claim 14 , wherein the coil spring applies a force to move the movable shield from the second position to the third position.

17 . The pen needle shield assembly of claim 14 , wherein

the hub includes an inner stepped surface; and

the spring contacts the inner stepped surface of the hub and an inner surface adjacent to a distal end of the movable shield.