Feedback Mechanism for an Injection Device

Abstract

A feedback mechanism for an injection device that is configured to deliver a medicament to a user is described. The feedback mechanism comprises a piston and a fluid chamber, and the piston is adapted to move into the fluid chamber during use of the injection device. The feedback mechanism also has a damper that is arranged to damp movement of the piston, and an indicator that is arranged to provide feedback to the user after the piston has moved a pre-determined distance into the fluid chamber.

1 . A feedback mechanism for an injection device, the injection device configured to deliver a medicament to a user, the feedback mechanism comprising:
 a piston;   a fluid chamber, wherein the piston is configured to move into the fluid chamber during use of the injection device;   a damper configured to damp movement of the piston; and   an indicator configured to provide feedback to the user after the piston has moved a predetermined distance into the fluid chamber.   
     
     
         2 . The feedback mechanism of  claim 1 , further comprising a biasing member configured to urge the piston into the fluid chamber. 
     
     
         3 . The feedback mechanism of  claim 1 , wherein the damper comprises a rotary agitator disposed within the fluid chamber, and wherein movement of the piston into the fluid chamber causes rotation of the rotary agitator such that the movement of the piston is damped by the rotary agitator. 
     
     
         4 . The feedback mechanism of  claim 3 , wherein the rotary agitator comprises one or more of fins, paddles, or angled plates that are configured to rotate within a fluid of the fluid chamber. 
     
     
         5 . The feedback mechanism of  claim 3 , wherein the piston comprises the rotary agitator. 
     
     
         6 . The feedback mechanism of  claim 5 , wherein a distal end of the piston comprises the rotary agitator. 
     
     
         7 . The feedback mechanism of  claim 3 , wherein the piston comprises an outward protrusion configured to engage a helical thread formed in a cylindrical bore of a plunger such that the movement of the piston into the fluid chamber causes the outward protrusion to move along the helical thread to rotate the piston. 
     
     
         8 . The feedback mechanism of  claim 1 , wherein the piston comprises a plate that extends across the fluid chamber, and the damper comprises one or more orifices located in the plate through which fluid flows as the piston moves into the fluid chamber. 
     
     
         9 . The feedback mechanism of  claim 1 , further comprising a recipient chamber into which fluid is urged as the piston moves into the fluid chamber, and wherein the damper comprises an orifice arranged between the fluid chamber and the recipient chamber. 
     
     
         10 . The feedback mechanism of  claim 9 , wherein the recipient chamber comprises a slider configured to be moved by fluid passing into the recipient chamber. 
     
     
         11 . The feedback mechanism of  claim 10 , wherein the slider is configured to engage the indicator after the slider has moved a predetermined distance to provide feedback to the user. 
     
     
         12 . The feedback mechanism of  claim 11 , wherein the indicator is a pre-stressed element configured to generate an audible sound when the slider engages the indicator after the slider has moved the predetermined distance. 
     
     
         13 . The feedback mechanism of  claim 1 , wherein the indicator is disposed between the piston and a part of the injection device, such that movement of the piston into the fluid chamber causes the indicator to be engaged by the piston, the indicator providing feedback to the user after being engaged by the piston. 
     
     
         14 . The feedback mechanism of  claim 1 , wherein the indicator is disposed between the piston and a part of the injection device, such that movement of the piston into the fluid chamber causes the indicator to be engaged by the part of the injection device, the indicator providing feedback to the user after being engaged by the part of the injection device. 
     
     
         15 . The feedback mechanism of  claim 1 , wherein the indicator comprises a sound generator configured to generate an audible sound. 
     
     
         16 . The feedback mechanism of  claim 15 , wherein the sound generator comprises a pre-stressed element configured to generate the audible sound when deflected. 
     
     
         17 . The feedback mechanism of  claim 16 , wherein the pre-stressed element is mounted to a plunger and arranged to be deflected as the plunger moves to displace a medicament. 
     
     
         18 . The feedback mechanism of  claim 17 , wherein the plunger comprises an arm to which the pre-stressed element is mounted. 
     
     
         19 . The feedback mechanism of  claim 18 , wherein the arm is arranged to engage the piston as the piston moves into the fluid chamber, the arm being arranged to deflect the pre-stressed element after engaging the piston. 
     
     
         20 . The feedback mechanism of  claim 1 , wherein the piston is in direct contact with a fluid within the fluid chamber, the fluid being distinct from a medicament within a reservoir of the injection device.