DOSE SETTING SENSOR ASSEMBLY WITH ALGORITHMIC AUTO CALIBRATION

Abstract

Drug delivery system comprising a dose setting member adapted to incrementally rotate in a first direction to set a dose, and incrementally rotate in an opposed second direction to reduce a set dose, the dose setting member having a rotational slack in each incremental rotational position. The system further comprises a rotary sensor adapted to detect the amount of rotation of the dose setting member during dose setting. Processor means is adapted to detect a first or second dose setting pattern when the final dose was set by rotating the setting member in the first respectively the second direction. When a first / second dose setting pattern is detected the detected amount of rotation is used to calculate a corrected amount of rotation using a first/ second algorithm compensating for a slack-induced error generated corresponding to the first/ second dose setting pattern.

Description

Claims

1. A drug delivery system, comprising: a housing defining a reference axis for rotation,a drug reservoir or structure for receiving a drug reservoir,drug expelling structure comprising: a dose setting member adapted to (i) incrementally rotate in a first direction to set a dose, and (ii) incrementally rotate in an opposed second direction to reduce a set dose, the dose setting member having a rotational slack in each incremental rotational position, andan actuation member adapted to cause a final set dose amount to be expelled,a rotary sensor adapted to detect the amount of rotation of the dose setting member relative to the housing during dose setting,a memory, andprocessor structure adapted to: detect a first dose setting pattern when the final dose was set by rotating the setting member in the first direction,detect a second dose setting pattern when the final dose was set by rotating the setting member in the second direction,when a first dose setting pattern is detected: based on the detected amount of rotation calculating a corrected amount of rotation using a first algorithm compensating for a slack-induced error generated corresponding to the first dose setting pattern,when a second dose setting pattern is detected: based on the detected amount of rotation calculating a corrected amount of rotation using a second algorithm compensating for a slack-induced error generated corresponding to the second dose setting pattern, andstore in the memory calculated corrected amounts of rotation or dose data corresponding thereto.

2. A drug delivery system as in claim 1, the drug expelling structure further comprising: a drive spring for expelling a set amount of drug from the drug reservoir,the dose setting member being adapted to (i) incrementally rotate in a first direction to set a dose and strain the drive spring correspondingly, and (ii) incrementally rotate in an opposed second direction to reduce a set dose and unstrain the drive spring correspondingly,wherein the actuation member is a release member adapted to release the strained drive spring to expel a final set dose amount.

3. A drug delivery system as in claim 2, the system being in the form of an assembly comprising a drug delivery device and an add-on device adapted to be releasably mounted on the drug delivery device, wherein the drug delivery device comprises: the housing,the drug reservoir or the structure for receiving a drug reservoir, andthe drug expelling structure comprising a drug delivery device dose setting member and a drug delivery device release member, the add-on device comprising: the rotary sensor, andthe processor structure.

4. A drug delivery system as in claim 3, wherein the add-on device further comprises: an add-on housing being releasably attachable to the drug delivery device housing,an add-on dose setting member, andan add-on release member axially moveable relative to the add-on dose setting member between a dose setting state and a dose expelling state, wherein: the add-on dose setting member is adapted to non-rotationally engage the drug delivery device dose setting member,the rotary sensor is adapted to detect the amount of rotation of the add-on dose setting member relative to the add-on housing during dose setting, andwhen in a mounted state, the add-on release member is adapted to release the drug delivery device release member when moved from the dose setting state to the dose expelling state.

5. A drug delivery system as in claim 1, wherein the rotary sensor is de-activated when the add-on release member is moved from the dose setting state to the dose expelling state.

6. A drug delivery system as in claim 1, the system being in the form of an assembly comprising a drug delivery device and an add-on device adapted to be releasably mounted on the drug delivery device, wherein the drug delivery device comprises: the housing,the drug reservoir or the structure for receiving a drug reservoir, andthe drug expelling structure comprising a drug delivery device dose setting member and a drug delivery device actuation member, the add-on device comprising: the rotary sensor, andthe processor structure.

7. A drug delivery system as in claim 1, the drug expelling structure further comprising: a piston rod adapted to engage and axially displace a piston in a loaded cartridge in a distal direction to thereby expel a dose of drug from the cartridge, anda drive member coupled directly or indirectly to the piston rod, wherein, when the drug expelling structure comprises a drive spring: the drive spring is coupled to the drive member, andthe release member is adapted to release the strained drive spring to rotate the drive member to expel the set dose amount.

8. A drug delivery system as in claim 1, wherein the processor structure for a detected first dose pattern is adapted to: detect a dose setting pause between two consecutive dose setting rotations in the first direction, andwhen one or more dose setting pauses are detected: based on the detected amount of rotation calculating a corrected amount of rotation using a third algorithm compensating for a slack-induced error generated corresponding to the first dose setting pattern when one or more dose setting pauses have been detected.

9. A drug delivery system as in claim 1, wherein: the drug expelling structure comprises an over-torque mechanism allowing the dose setting member to be rotated further in the first direction when a predetermined maximum dose has been set, andthe processor structure is adapted to detect an over-torque condition and calculate the amount of rotation of the dose setting member relative to the housing corresponding to the set maximum dose.

10. A drug delivery system as in claim 1, further comprising: transmitter structure adapted to transmit dose related data to an external receiver.

11. An add-on device adapted to be releasably mounted on a drug delivery device, the drug delivery device comprising: a device housing defining a reference axis for rotation,a drug reservoir or structure for receiving a drug reservoir, anddrug expelling structure comprising: a device dose setting member adapted to (i) incrementally rotate in a first direction to set a dose, and (ii) incrementally rotate in an opposed second direction to reduce a set dose, the dose setting member having a rotational slack in each incremental rotational position, anda device actuation member adapted to cause a final set dose amount to be expelled, the add-on device comprising: an add-on housing being releasably attachable to the device housing,an add-on dose setting member adapted to non-rotationally engage the device dose setting member,an add-on actuation member axially moveable relative to the add-on dose setting member between a dose setting state and a dose expelling state, the add-on actuation member being adapted to, when in a mounted state, actuate the device actuation member when moved from the dose setting state to the dose expelling state,a rotary sensor adapted to detect the amount of rotation of the add-on dose setting member relative to the add-on housing during dose setting, andprocessor structure adapted to: detect a first dose setting pattern when the final dose was set by rotating the add-on dose setting member in the first direction,detect a second dose setting pattern when the final dose was set by rotating the add-on dose setting member in the second direction, wherein: when a first dose setting pattern is detected: based on the detected amount of rotation calculating a corrected amount of rotation using a first algorithm compensating for a slack-induced error generated corresponding to the first dose setting pattern, andwhen a second dose setting pattern is detected: based on the detected amount of rotation calculating a corrected amount of rotation using a second algorithm compensating for a slack-induced error generated corresponding to the second dose setting pattern, wherein: the add-on dose setting member is adapted to non-rotationally engage the dose setting member,the rotary sensor is adapted to detect the amount of rotation of the add-on dose setting member relative to the add-on housing during dose setting, andwhen in a mounted state, the add-on actuation member is adapted to actuate the device actuation member when moved from the dose setting state to the dose expelling state.

12. An add-on device as in claim 11, the drug expelling structure further comprising: a drive spring for expelling a set amount of drug from the drug reservoir,the dose setting member being adapted to: (i) incrementally rotate in a first direction to set a dose and strain the drive spring correspondingly, and (ii) incrementally rotate in an opposed second direction to reduce a set dose and unstrain the drive spring correspondingly, andthe actuation member being a release member adapted to release the strained drive spring to expel a final set dose amount, wherein: when in a mounted state, the add-on actuation member is adapted to actuate the device actuation member when moved from the dose setting state to the dose expelling state, the add-on actuation member having a maximum axial travel relative to the add-on housing of 10 mm.

13. An add-on device as in claim 11, wherein the processor structure for a detected first dose pattern is adapted to: detect a dose setting pause between two consecutive dose setting rotations in the first direction, andwhen one or more dose setting pauses are detected: based on the detected amount of rotation calculating a corrected amount of rotation using a third algorithm compensating for a slack-induced error generated corresponding to the first dose setting pattern when one or more dose setting pauses have been detected.

14. An add-on device as in claim 11, wherein: the drug expelling structure comprises an over-torque mechanism allowing the dose setting member to be rotated further in the first direction when a predetermined maximum dose has been set, andthe processor structure is adapted to detect an over-torque condition and calculate the amount of rotation of the dose setting member relative to the housing corresponding to the set maximum dose.

15. An add-on device as in claim 11, wherein the rotary sensor is in the form of: (i) a galvanic rotary encoder comprising a circular array of encoder segments, or(ii) a magnetic sensor comprising at least one magnetometer adapted to measure a magnetic field from a moving magnet.