NEEDLE RETRACTION MECHANISM FOR AUTOINJECTOR
An aspect of some embodiments of the present invention relates to a needle safety mechanism for an autoinjector. Optionally, an unshielded needle may be safeguarded when there is a change in resistance discharging the injector payload. The needle may optionally be safeguarded by retraction to a protected space and/or by deployment of a needle shield. Optionally the stress that prompts safeguarding the needle may include a torque and/or a linear stress.
1 . A drug injector having a needle safeguard mechanism comprising:
a housing including a shielded location;
a point of the needle protruding from said housing;
a retractor mechanically coupled to the needle, said retractor retracting said point to said shielded location; and
a sensor operationally linked to said retractor, said sensor sensing a resistance to discharging of the drug through the needle;
wherein said retractor is responsive to said sensor to retract said point to said shielded location in response to said resistance.
2 . The drug injector of claim 1 , wherein said retractor includes a support of the needle and wherein said support reverts to a retracted state in response to said resistance.
3 . The drug injector of claim 2 , wherein said support includes an interference element, and wherein said resistance overcomes said interference element.
4 . The drug injector of claim 3 , wherein said interference element includes an annular snap.
5 . The drug injector of claim 2 , wherein said support includes a telescoping assembly.
6 . The drug injector of claim 5 , wherein said telescoping assembly is held in an extended mode by an interference element.
7 . The drug injector of claim 2 , further comprising:
a driver driving said discharging and wherein said driver is supported by said support, and wherein in response to said resistance said driver produces a stress on said support and wherein said stress reverts said support to said retracted state.
8 . The drug injector of claim 7 , further including:
a plunger and wherein said driver drives said discharging by imparting a linear motion to said plunger and wherein said resistance is to said linear motion of said plunger.
9 . The drug injector of claim 1 further comprising:
a lock mechanically coupled to the needle, said lock retaining said point in said protruding position; and wherein said retractor is operationally linked to said lock to release said lock in response to said resistance.
10 . The drug injector of claim 9 , wherein said sensor is further sensitive to a second condition, and said lock retains said point in said protruding position until said second condition is met.
11 . The drug injector of claim 10 , wherein said point is biased to said shielded position.
12 . The drug injector of claim 9 , wherein said lock includes at least one element selected from the group consisting of an interference element, an annular snap, a rib snap, a flange and a groove.
13 . The drug injector of claim 10 , wherein said second condition is a volume of said discharging passing a predetermined threshold.
14 . The drug injector of claim 1 , wherein the sensor senses a torque.
15 . The drug injector of claim 1 , wherein said retracting is in response to a change in said resistance.
16 . The drug injector of claim 1 , wherein said retracting is in response to an increase in said resistance.
17 . The drug injector of claim 1 , wherein said retracting is in response to a decrease in said resistance.
18 . The drug injector of claim 1 , wherein said retracting is in response said resistance passing a threshold.
19 . A method of safeguarding a needle of an injector comprising:
discharging a drug through the needle;
sensing a resistance to said discharging, and
safeguarding the needle in response to said resistance.
20 . The method of claim 19 , wherein said safeguarding is in response to said resistance passing a predetermined threshold.
21 . The method of claim 19 wherein said safeguarding is in response to a change in said resistance.
22 . The method of claim 19 wherein said safeguarding is in response to an increase in said resistance.
23 . The method of claim 19 wherein said safeguarding is in response to a decrease in said resistance.
24 . The method of claim 19 , further comprising:
locking the needle in an extended position during said discharging; and
wherein said safeguarding includes releasing said locking.
25 . The method of claim 19 , wherein said resistance occurs upon at least one event selected from the group consisting of a completion of said discharging, a fluid leak, jamming of a mechanical component, disconnection of a mechanical component and obstruction of a fluid flowpath.
26 . The method of claim 19 , further comprising:
inhibiting said safeguarding until a second condition is met.
27 . The method of claim 26 , wherein said second condition includes said discharging passing a predetermined volume.
28 . The method of claim 27 , wherein said volume of discharging is measured by counting motor rotations.
29 . The method claim 19 , wherein the needle is a component of a pre filled syringe inside autoinjector and further comprising:
placing the autoinjector on a patient;
extending the needle to an extended position subsequent to said placing and prior to said discharging, and
wherein said safeguarding includes retracting the needle to a retracted position.
30 . The method claim 19 , further comprising:
indicating that it is safe to remove an injection device including said needle after said safeguarding.