Drug delivery devices and dose measurement systems

Abstract

The present disclosure relates to a medication delivery device comprising a rotation sensor as part of or adapted to be part of a medication injection device, thereby measuring the amount of a dose dispensed by the medication injection device.

Description

Technical Field

[0001] The present disclosure relates to drug delivery devices and dose measurement systems for drug delivery devices. Background Art

[0002] There are many diseases that need to be treated regularly by delivering medicaments using a medicament delivery device. This delivery can be carried out using an injection device, applied by medical staff or the patient himself. For example, type 1 and type 2 diabetes can be treated by the patient himself by injecting insulin doses, for example, once or several times a day. For example, a pre-filled disposable insulin pen can be used as an injection device. Alternatively, a reusable pen can be used. A reusable pen allows an empty medicament cartridge to be replaced with a new medicament cartridge. Any pen can have a set of one-way needles, which are replaced before each use. The insulin dose to be injected can then be manually selected, for example, at the insulin pen by turning the dose knob and observing the actual dose from the dose window or display of the insulin pen. The dose is then injected by inserting the needle into a suitable skin part and pressing the injection button of the insulin pen. In order to be able to monitor insulin injection, for example, to prevent the insulin pen from being manipulated incorrectly or to record the dose applied, it is desirable to measure information related to the condition and / or use of the injection device, such as information about the injected insulin dose. Summary of the invention

[0003] It is an object of the present disclosure to provide an improved medicament delivery device and a dose measurement system for a medicament delivery device.

[0004] According to the present disclosure, a drug delivery device is provided, comprising:

[0005] a medicament reservoir; a dispensing mechanism operable to dispense the medicament from the reservoir, the dispensing mechanism comprising a sleeve configured to rotate during dispensing of the medicament and having a plurality of configurations at an end of the sleeve; and

[0006] A dose measurement system comprising a processor and at least one mechanically actuated sensor, the at least one mechanically actuated sensor being configured such that, in use, rotation of a sleeve causes a configuration-by-configuration engagement of the sensor such that the sensor detects rotation of the sleeve, the processor being configured to determine a dose dispensed from a medicament reservoir based on the detected rotation of the sleeve.

[0007] The use of a mechanical sensor engaged with the sleeve provides a compact system for determining the dose dispensed from the medicament reservoir. Mechanical sensors are generally more energy efficient than other types of sensors (e.g., light gates), and therefore smaller batteries can be used. Due to the configuration on the sleeve where the mechanical sensor engages the dispensing mechanism, the system can be more portable than if the sensor detects external components of the device.

[0008] In some embodiments, the plurality of configurations comprises a plurality of teeth.

[0009] In some embodiments, the formations are formed on the proximal end of the sleeve.

[0010] The formations on the proximal end of the sleeve allow the sensor to be axially aligned with the sleeve.The sensor may be disposed proximally of the sleeve.

[0011] In some embodiments, the sleeve is a dial sleeve or a drive sleeve.

[0012] In some embodiments, the sensor includes a sensing member configured to move from an unactuated state to an actuated state when the sensing member engages with one of the structures during rotation of the sleeve, wherein the sensor detects movement of the sensing member between the unactuated state and the actuated state.

[0013] In some embodiments, each formation includes a leading edge, and wherein during rotation of the sleeve, engagement of the sensor with the leading edge of a first formation in the formations to engagement of the sensor with the leading edge of an adjacent second formation in the formations represents one encoding period, and wherein the sensor is actuated for between 40% and 60% of the encoding period, and preferably, the sensor is actuated for about 50% of the encoding period. This configuration produces a symmetrical scheme, which can contribute to the robustness of tolerances since tolerances are symmetrically distributed in many cases.

[0014] In some embodiments, the medicament delivery device further comprises a dose dial and a housing, wherein the dose dial is configured to rotate relative to the housing to set a dose of the medicament to be delivered by the dispensing mechanism, and wherein the sensor is mounted to the dose dial.

[0015] The sensor mounted to the dose dial allows for a compact drug delivery device. In some embodiments, the sensor is mounted to the interior of the dose dial so that the dose measurement system is small and compact.

[0016] In some embodiments, the drug delivery device comprises a torque limiter, wherein the sensor is mounted to the dose dial via the torque limiter, such that rotation of the dose dial relative to the housing with a torque greater than a predetermined limit causes the torque limiter to move to an open state so that the dose dial can be rotated relative to the sensor, and preferably, the torque limiter comprises an overload clutch.

[0017] The torque limiter prevents damage to the sensor in the event that a user applies a large torque on the dose dial during setting of a dose to be delivered by the measured delivery device.

[0018] In some embodiments, the drug delivery device further includes a one-way mechanism, wherein the sensor is mounted to the dose dial via the one-way mechanism such that the sensor is resisted from rotating relative to the dose dial in a direction in which the sleeve rotates during drug dispensing, and is allowed to rotate relative to the dose dial in an opposite direction in which the sleeve rotates during drug dispensing.

[0019] In the event that a user pushes the sleeve to rotate in a direction opposite to the direction in which the sleeve rotates during dispensing of medicament, then the one-way mechanism prevents damage to the sensor as the sensor will rotate together with the sleeve in said opposite direction.

[0020] According to another aspect, a dose measurement system for a drug delivery device is provided, wherein the drug delivery device comprises: a housing containing a reservoir for a drug; and a dispensing mechanism operable to dispense the drug from the reservoir and comprising a component configured to rotate during drug dispensing, the component comprising a plurality of configurations; and an actuator configured to be movable relative to the housing when actuated to operate the dispensing mechanism to dispense the drug from the reservoir, the dose measurement system comprising: a sensor movable from an idle position to a detection position, wherein rotation of the component causes each configuration to be detected by the sensor, such that the sensor detects the rotation of the component; a processor configured to determine a dose dispensed from the drug reservoir based on the detected rotation of the component; and

[0021] an activation switch movable from an initial closed state to an open state to activate the dose measurement system upon actuation of the actuator, the sensor being configured to be mounted to the actuator such that actuation of the actuator causes the sensor to move relative to the housing to reach a detection position, wherein the activation switch reaches the open state before the sensor reaches the detection position.

[0022] The configuration of the sensor and the activation switch ensures that the dose measurement system is activated before the sensor reaches the detection position. This helps to ensure that the sensor is not in the detection position before the dose measurement system is powered on.

[0023] In some embodiments, the actuator is slidable relative to the housing. Sliding movement of the actuator may be easier for the patient, especially if the patient is elderly or frail.

[0024] In some embodiments, the activation switch includes a pivoting member that pivots from a closed state to an open state to activate the dose measurement system.

[0025] In some embodiments, the drug delivery device includes a stopper, and wherein the activation switch is configured to rest on the stopper when the activation switch is in the off state.

[0026] In some embodiments, the activation switch is configured to engage a portion of the drug delivery device when the actuator is moved to operate the dispensing mechanism such that the activation switch is urged to an on state, and preferably, the portion comprises a portion of the dispensing mechanism.

[0027] This configuration allows actuation of the start switch without the need for additional components.In some embodiments, the portion comprises a drive sleeve of a dispensing mechanism.

[0028] In some embodiments, the activation switch is configured to move the activation switch a first distance from the off state to the on state, and the sensor is configured to move the sensor a second distance from the rest position to the detection position, wherein the second distance is greater than the first distance. This helps ensure that the activation switch reaches the on position before the sensor reaches the detection position.

[0029] In some embodiments, the dose measurement system comprises a first radial support and a second radial support, wherein the actuator is rotatably mounted to a portion of the device via the first support and the second support, the first support and the second support being axially spaced apart. The portion of the device may be, for example, a rotatable sleeve of the device (e.g., a dial sleeve) or may be a housing.

[0030] In some embodiments, the dose measurement system comprises a support member and a coupling member, wherein the dose setting dial is fixed relative to the support member, and wherein the support member is coupled to the coupling member, and preferably the support member is coupled to the coupling member via a pivot.

[0031] In some embodiments, the support member is rotatably coupled to the coupling member via at least one radial bearing and preferably via a first radial bearing and a second radial bearing. Optionally, the second radial bearing is axially spaced apart from the first radial bearing in the direction of actuation movement of the actuator.

[0032] In some embodiments, the dose measurement system has any of the features discussed above. In some embodiments, a drug delivery device is provided, the drug delivery device comprising a dose measurement system having any of the features discussed above.

[0033] According to another aspect, there is provided a dose measurement system for a drug delivery device, wherein the drug delivery device comprises a reservoir for a drug and a dispensing mechanism operable to dispense the drug from the reservoir, the dispensing mechanism comprising a component configured to rotate during dispensing of the drug, the component comprising a plurality of first encoder areas and a plurality of second encoder areas, the dose measurement system comprising: a first sensor and a second sensor, the first sensor and the second sensor being offset such that, in use, rotation of the component causes one of the first encoder areas to align with the first sensor while one of the second encoder areas is aligned with the second sensor, and then one of the second encoder areas to align with the first sensor while one of the first encoder areas is aligned with the second sensor, the first sensor and the second sensor being configured to distinguish between the first encoder area and the second encoder area to detect rotation of the component;

[0034] A processor is configured to determine a dose to be dispensed from the medicament reservoir based on the detected rotation of the component.

[0035] The arrangement of the offset first and second sensors increases the resolution of the component rotation measurement for a given size of the encoded area, thereby allowing a more accurate determination of the dose dispensed from the medicament reservoir.

[0036] In some embodiments, the component includes a plurality of configurations, wherein each first encoder region includes at least a portion of a corresponding configuration detectable by the first sensor and the second sensor when the component is rotated, wherein the second encoder regions are disposed between adjacent first encoder regions.

[0037] In some embodiments, wherein each formation comprises teeth, wherein each first encoded region comprises at least a portion of a corresponding tooth detectable by the first and second sensors when the component is rotated, wherein each second encoder comprises at least gaps between adjacent teeth.

[0038] In some embodiments, the first sensor and the second sensor are arranged such that for all rotational positions of the component in which the first sensor is aligned with one of the first encoded regions, the second sensor is aligned with one of the second encoded regions.

[0039] This helps ensure that for a given number and size of encoded regions, the maximum resolution of component rotation measurement can be achieved. Furthermore, it can be determined that initial axial movement will cause the first encoded region to align with one of the first and second sensors, and thus erroneous readings due to initial axial movement can be ignored.

[0040] In some embodiments, the component includes multiple encoding periods, wherein each encoding period includes a first encoding region in the first encoding regions and an adjacent second encoding region, wherein for a given rotational position of the component, the first sensor is aligned with a portion of one of the encoding periods and the second sensor is aligned with a different portion of one of the encoding periods.

[0041] In some embodiments, the dose measurement system further comprises a third sensor, the third sensor being aligned with a portion of one of the encoding periods different from the first sensor and the second sensor when the component is in the given rotational position.

[0042] The processor is thus able to determine the direction of rotation of the component.

[0043] In some embodiments, the dose measurement system further comprises a fourth sensor, which is aligned with a portion of one of the encoding periods that is different from the first sensor, the second sensor, and the third sensor when the component is in the given rotational position. The processor is thus able to determine the rotational direction of the component.

[0044] In some embodiments, the dose measurement system further comprises a third sensor configured such that, in use, when the component is rotated, the third sensor is aligned with one of the first encoded regions at the same time as the first sensor is aligned with one of the first encoded regions.

[0045] If the first sensor fails to detect the coded region due to a detection error, the third sensor provides redundancy and also allows filtering of impossible detection events. Thus, there is a pairwise redundancy that allows detection and compensation of erroneous switch state detections.

[0046] In some embodiments, the dose measurement system further comprises a fourth sensor configured such that, in use, when the component rotates, the fourth sensor is aligned with one of the first coded regions at the same time as the second sensor is aligned with one of the first coded regions.

[0047] If the second sensor fails to detect the coded region due to a detection error, the fourth sensor provides redundancy and also allows filtering of impossible detection events. Thus, there is a pairwise redundancy that allows detection and compensation of erroneous switch state detections.

[0048] In some embodiments, when the first sensor is aligned with the transition between the first coding region and the second coding region, the third sensor is also aligned with the transition between the first coding region and the second coding region. In some embodiments, when the second sensor is aligned with the transition between the first coding region and the second coding region, the fourth sensor is also aligned with the transition between the first coding region and the second coding region.

[0049] In some embodiments, each of the first encoded region and the second encoded region extends through the same predetermined angle around the rotational axis of the component.

[0050] In some embodiments: the predetermined angle is approximately 15 degrees or 30 degrees.

[0051] In some embodiments, the second sensor is offset from the first sensor in the first direction about the rotational axis by an odd integer multiple of an angle subtended by each first encoded region about the rotational axis.

[0052] In some embodiments, the second sensor is offset from the first sensor 165 degrees about the axis of rotation in the first direction.

[0053] In some embodiments, each of the first encoded regions and the second encoded regions includes a length extending in a rotational direction of the component, wherein the dose measurement system includes a third sensor that is offset from the first sensor and the second sensor so that in use when the first sensor is aligned with one of the first encoded regions and the second sensor is aligned with one of the second encoded regions, the third sensor is aligned with a different portion of the length along one of the first encoded regions and the second encoded region.

[0054] In some embodiments, the processor is configured to determine a dose dispensed from the medicament reservoir by a process comprising counting a number of transitions between the first coded region and the second coded region detected by the first sensor and the second sensor.

[0055] In some embodiments, the first sensor and the second sensor are configured to move from an idle position to a detection position, wherein movement of the sensor to the detection position causes one of the first area and the second area to align with one of the first coded areas, and wherein the processor is configured such that when determining the dispensed dose, the processor compensates for the alignment when the sensor moves to the detection position.

[0056] This allows for improved accuracy in embodiments where the sensor is moved axially to the detection position. This is because, in some embodiments, such axial movement will cause one of the first sensor and the second sensor to align with the first coded region, which will appear as an erroneous reading of the transition to the first coded region. The processor can disregard this erroneous reading to more accurately determine the dose dispensed.

[0057] In some embodiments, the processor is configured to determine a dose to be dispensed from the medicament reservoir based on a signal from one of the first sensor and the second sensor and an inverted signal from the other of the first sensor and the second sensor.

[0058] In some embodiments, the processor is configured to determine a dose to be dispensed from the medicament reservoir based on a superposition of a signal from one of the first sensor and the second sensor and an inverted signal from the other of the first sensor and the second sensor.

[0059] In some embodiments, the processor is configured to determine a dose to be dispensed from the medication reservoir by comparing the superposition to a first threshold and a second threshold that is greater than the first threshold, and preferably counting the number of times the superposition transitions from a value below the first threshold to a value greater than the second threshold and / or from a value above the second threshold to a value below the first threshold.

[0060] This helps improve the accuracy of dose determination by helping to filter out errors such as sensor noise and switch jitter. Additionally, having four sensors can further improve accuracy because two simultaneous errors can be ignored.

[0061] In some embodiments, the dose measurement system has any of the features discussed above.

[0062] In some embodiments, a drug delivery system including a dose measurement system is provided.

[0063] These and other aspects of the disclosure will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0065] FIG1 is an exploded view of a drug delivery device;

[0066] 2 is a cross-sectional side view of a portion of a medication delivery device including a dose measurement system according to an embodiment;

[0067] FIG3 is a cross-sectional side view of the drug delivery device of FIG2 before the actuator is actuated by a user;

[0068] FIG4 is a cross-sectional side view of the device of FIG2 once the actuator has been actuated by a user;

[0069] FIG5 is a perspective view of an encoder ring of the device of FIG2;

[0070] Fig. 6 is a perspective view of the dial sleeve of the device of Fig. 2;

[0071] Fig. 7 is a perspective view of a portion of the dial sleeve and the sensor of the device of Fig. 2;

[0072] Fig. 8 is a side view of a portion of the dial sleeve and the sensor of the device of Fig. 2 with the sensing member in an unactuated state;

[0073] Fig. 9 is a perspective view of a portion of the dial sleeve and the sensor of the device of Fig. 2 with the sensing member in an actuated state;

[0074] FIG10 is a schematic side view of the sensor of the device of FIG2 showing the sensing member being actuated;

[0075] FIG11 is a schematic side view of a first coding region and a second coding region of a dial sleeve of the device of FIG2 ;

[0076] FIG12 is a schematic side view of a first coded region and a second coded region of a sensor actuating the device of FIG2;

[0077] FIG13 is a cross-sectional side view of a portion of the device of FIG2 showing a portion of the support member and the coupling member;

[0078] FIG14 is a cross-sectional side view of a portion of the device of FIG2 showing a portion of a coupling member;

[0079] FIG15 is a schematic block diagram of a dose measurement system of the apparatus of FIG2 ;

[0080] FIG16A is a schematic diagram of a sensor of another embodiment of a dose measurement system;

[0081] FIG16B is a schematic diagram of a sensor of another embodiment of a dose measurement system;

[0082] FIG16C is a schematic diagram of a sensor of another embodiment of a dose measurement system;

[0083] FIG. 17 shows a signal output from a sensor of the embodiment of FIG. 16A ;

[0084] FIG. 18 shows the signals output from the sensor of the embodiment of FIG. 16A and the superimposed signals;

[0085] FIG19 is a top view of the sensor and activation switch of the embodiment of FIG16B;

[0086] Fig. 20 shows the signals output from the sensor and activation switch of the embodiment of Fig. 16B and the superimposed signal;

[0087] FIG21 is a top view of the sensor and activation switch of the embodiment of FIG16C;

[0088] FIG22 is a perspective view of a portion of a dial sleeve and a sensor according to another embodiment; and

[0089] 23 is a circuit diagram of an embodiment of a dose measurement system. DETAILED DESCRIPTION

[0090] In the following disclosure, embodiments will be described with reference to insulin injection devices. However, the present disclosure is not limited to such applications and may be deployed equally well with medicament delivery devices that eject other medicaments.

[0091] The term "distal" refers to a position relatively closer to a medication delivery site (eg, an injection site in the case of an injection device), and the term "proximal" refers to a position relatively farther from a medication delivery site.

[0092] FIG1 is an exploded view of a drug delivery device 1. In this example, the drug delivery device 1 is an injection device 1, such as Sanofi's Insulin injection pen or Sanofi Insulin injection pens, however, the present disclosure is also compatible with other types and manufactures of injection pens as described below. The present disclosure is also compatible with other types of drug delivery devices, such as needle-free injectors.

[0093] The injection device 1 of FIG. 1 is a prefilled injection pen comprising a housing 2 and containing a reservoir 14 for a medicament, in this embodiment, an insulin container 14. A needle 15 can be attached to the reservoir 14. The injection device 1 can be disposable or reusable. The needle 15 is protected by an inner needle cap 16 and an outer needle cap 17 and / or an alternative cap 18.

[0094] The dose of insulin to be ejected from the injection device 1 can be programmed by moving a dose setting member 12, which in the present embodiment is a dose setting dial 12 that can be rotated relative to the housing 2 to allow a dose to be "dialed in". The currently programmed dose is then displayed via a dose window 13, for example in multiples of units. For example, where the injection device 1 is configured to administer human insulin, the dose may be displayed in so-called international units (IU), where one IU is the biological equivalent of approximately 45.5 micrograms of pure crystalline insulin (1 / 22 mg). Other units may be employed in a drug delivery device to deliver analog insulin or other medicaments.

[0095] The dose window 13 may be in the form of an aperture in the housing 2 that allows a user to view a limited portion of the number sleeve 10 that is configured to move when the dose setting dial 12 is turned to provide a visual indication of the currently programmed dose. It should be noted that the selected dose may be displayed differently from the dose window 13 shown in FIG. 1 as well. For example, due to space limitations on the number sleeve 10, only every other dose unit may be shown. Unnumbered dose units may be represented by tick marks between the displayed numbers. Alternatively, the number sleeve 10 may remain stationary during the dose dialing phase, and the dose window 13 may move as the dose is dialed in to reveal the number corresponding to the dose dialed. In either case, the number sleeve 10 may be a component that rotates when a dose is dispensed from the injection device 1.

[0096] In this example, the dose setting dial 12 comprises one or more formations 12a, 12b, 12c that facilitate programming as they improve the grip felt by the user when holding the dose setting dial 12. In another example (not shown), the dose setting dial comprises no formations.

[0097] The injection device 1 can be configured so that rotating the dose setting dial 12 causes a mechanical click to provide acoustic feedback to the user. The number sleeve 10 interacts mechanically with the piston in the insulin container 14. When the needle 15 is pierced into the skin portion of the patient and then the dose setting dial 12 is pushed axially relative to the housing 2, the insulin dose displayed in the display window 13 will be ejected from the injection device 1. Therefore, the dose setting dial 12 forms an actuator that can be actuated by the user to dispense the medicament. When the needle 15 of the injection device 1 is retained in the skin portion for a certain time after pushing the dose setting dial 12, a higher percentage of the dose is actually injected into the patient. The ejection of the insulin dose can also cause a mechanical click, but the mechanical click is different from the sound generated when the dose setting dial 12 is rotated to set the dose to be delivered.

[0098] The injection device 1 comprises a dial sleeve 10, which in the present embodiment is the same component as the number sleeve 10. In other embodiments (not shown), the dial sleeve 10 may be fixed to the proximal end of the number sleeve 10.

[0099] The dial sleeve 10 has a proximal end close to the dose setting dial 12. The dial sleeve 10 (and the number sleeve 10 being the same component) rotates relative to the dose setting dial 12 during dose discharge, but not during dose dialing. During dose dialing, the user rotates the dose setting dial 12 relative to the housing 2, which causes a corresponding rotation of the dial sleeve 10 relative to the housing 2.

[0100] In order to operate the injection device 1 to dispense a medicament from the container 14, the dose setting dial 12 is configured to move axially a short distance relative to the housing 2 and the dial sleeve 10 of the injection device 1. This movement occurs when a user applies a force on the end of the dose setting dial 12. For example, the user pushes the dose setting dial 12 axially towards the injection site. This movement disengages the clutch (not shown) and allows the dial sleeve 10 and other internal components of the injection device 1 to rotate relative to the dose setting dial 12. Alternatively, the injection device 1 may include a separate injection button (not shown in FIG. 1) that is mounted to the dose setting dial 12 and moves axially relative to the housing 2 to cause the medicament to be dispensed. The injection button may be located at the proximal end of the dose setting dial 12.

[0101] In various embodiments, during delivery of an insulin dose, the dose setting dial 12 is moved axially to its initial position (ie, without rotation), and the number sleeve 10 is rotated to return to its initial position, for example to display a dose of zero units.

[0102] The injection device 1 can be used for several injection procedures until the insulin container 14 is emptied or the medication in the injection device 1 reaches its expiration date (eg, 28 days after the first use).

[0103] Before using the injection device 1 for the first time, it may be necessary to perform a so-called "priming shot" to remove air from the insulin container 14 and the needle 15, for example by selecting two units of insulin and pressing the dose setting dial 12 while keeping the needle 15 of the injection device 1 pointing upwards. For ease of presentation, in the following it will be assumed that the ejected dose substantially corresponds to the injected dose, such that, for example, the number of medicament dosage units ejected from the injection device 1 is equal to the number of medicament dosage units received by the user. However, in some applications of the device, it may be necessary to take into account the difference (e.g., loss) between the ejected amount and the injected dose.

[0104] Referring now to FIGS. 2 to 15 , an embodiment of a drug delivery device 100 is shown. The drug delivery device 100 is similar to the drug delivery device 1 described with respect to FIG. 1 , and therefore a detailed description of the common features of the drug delivery device 100 will not be repeated hereinafter. The difference is that the drug delivery device 100 includes a dose measurement system 101.

[0105] The drug delivery device 100 comprises a housing 102 containing a reservoir (not shown) for a drug. The drug delivery device 100 further comprises a dispensing mechanism 104 operable to dispense the drug from the reservoir.

[0106] The dispensing mechanism 104 includes a clutch 105, a dial sleeve 106, a drive sleeve 107, a drive member (not shown), a plunger rod (not shown) and a piston (not shown). The drive member may include a biasing member (not shown, such as a spring) and is configured to bias the drive sleeve 107 to rotate relative to the housing 102.

[0107] The drive sleeve 107 is coupled to the plunger rod such that rotation of the drive sleeve 107 in a first rotational direction (indicated by arrow "X" in FIGS. 7 to 11) causes the plunger rod to move axially in a distal direction to dispense the medicament from the reservoir. More specifically, a piston (not shown) is mounted to the distal end of the plunger rod such that during rotation of the drive sleeve 107 in the first rotational direction X, axial movement of the plunger rod in the distal direction causes the piston to slide distally within the reservoir to dispense the medicament therefrom.

[0108] In one embodiment, the drive sleeve 107 and the plunger rod include corresponding threads (not shown) that are engaged so that rotation of the drive sleeve 107 causes axial movement of the plunger rod. In other embodiments (not shown), the drive sleeve 107 is coupled to the plunger rod via one or more intermediate components (not shown).

[0109] The clutch 105 is initially in an engaged position in which the clutch 105 prevents the drive sleeve 107 from rotating in the first rotational direction X under the force of the drive member. In some embodiments, the clutch 105 has one or more splines (not shown) or other engagement elements that engage with the drive sleeve 107 or another component to prevent the drive sleeve 107 from rotating relative to the housing 102 when the clutch 105 is in the engaged position.

[0110] The drug delivery device 100 further comprises a dose setting member 108, which in this embodiment is a dose setting dial 108 mounted to the proximal end of the housing 102. The dose of drug to be discharged from the drug delivery device 100 can be programmed or "dialed in" by rotating the dose setting dial 108, and then displaying the currently programmed dose via a dose window (not shown), for example in multiples of units. In some embodiments, the dose setting dial 108 is rotated relative to the housing 102 in a second rotational direction opposite to the first rotational direction X, so that the dial sleeve 106 is also rotated relative to the housing 102 in the second rotational direction from an initial position (indicating a "zero" dose) until the desired dose is selected.

[0111] The dial sleeve 106 has a proximal end close to the dose setting dial 108. The dial sleeve 106 (and the number sleeve 106 as the same component) rotates relative to the dose setting dial 108 during dose ejection, not during dose dialing. In other embodiments (e.g., embodiments in which the dose setting dial 108 includes a separate actuator (such as a button)), the dial sleeve 106 does not rotate relative to the dose setting dial 108 during dose ejection, but the dose setting dial 108 rotates together with the dose sleeve 106, and optionally, both the dose setting dial 108 and the dial sleeve 106 rotate relative to the actuator.

[0112] During a dose dialing process, the user rotates the dose setting dial 108 in a second rotational direction relative to the housing 102 , which causes a corresponding rotation of the dial sleeve 106 relative to the housing 102 .

[0113] The dispensing mechanism 104 further comprises a number sleeve 106, which in this embodiment is the same component as the dial sleeve 106. In other embodiments (not shown), the dial sleeve may be fixed to the number sleeve.

[0114] The user will be able to determine that the desired dose has been selected by viewing the number sleeve 106 through a viewing window (not shown) in the housing 102 .

[0115] The dose setting dial 108 forms an actuator that can be actuated by a user to dispense a medicament. In more detail, the dose setting dial 108 is axially slidable relative to the housing 102 to operate the dispensing mechanism 104 to dispense a medicament from the reservoir. In some embodiments, rotation of the dose setting dial 108 in the second rotational direction during dose dialing causes the dose setting dial to move axially in the proximal direction. In other embodiments, rotation of the dose setting dial 108 in the second rotational direction during dose dialing does not cause the dose setting dial 108 to move axially.

[0116] In operation, the dose setting dial 108 is configured to move axially a short distance relative to the housing 102. This movement occurs when a user applies a force on the dose setting dial 108 (e.g., the user pushes the dose setting dial 108 axially in a distal direction toward the injection site). This axial movement of the dose setting dial 108 disengages the clutch 105, causing the clutch 105 to move to a disengaged position. For example, the distal movement of the dose setting dial 108 may cause a corresponding distal movement of the clutch 105, which disengages the clutch 105, e.g., disengages a spline or other engagement element (not shown). Disengaging the clutch 105 allows the dial sleeve 106 and the drive sleeve 107 to rotate relative to the housing 102 and the dose setting dial 108 in a first rotational direction X under the force of the drive member to dispense a medicament from the reservoir.

[0117] As long as the dose setting dial 108 remains depressed by the user, the clutch 105 will remain in the disengaged position and thus the dial sleeve 106 and the drive sleeve 107 will continue to rotate in the first rotational direction X under the force of the drive member to deliver the medicament to the user until the dial sleeve 106 reaches the initial position. The dose setting dial 108 may be biased proximally by a dial biasing member (not shown).

[0118] The dial sleeve 106 includes a cylindrical body 110 and an encoder ring 111 disposed on the proximal end of the body 110. In the present embodiment, the encoder ring 111 is attached to the body 110, but in other embodiments, the encoder ring 111 may be integrally formed with the body 110 (e.g., the encoder ring 111 and the body 110 are molded or cast from a single portion of material).

[0119] The encoder ring 111 comprises a plurality of formations 112, which in this embodiment are teeth 112, with gaps 113 between them. The teeth 112 extend proximally.

[0120] The dose measurement system 101 further comprises a mechanically actuated sensor 114 configured such that, in use, rotation of the dial sleeve 106 in the first rotational direction X causes the individual formations 112 to engage the sensor 114 such that the sensor 114 detects the rotation of the dial sleeve 106 .

[0121] The dose measurement system 101 further includes one or more processors 115 configured to determine a dose dispensed from the medicament reservoir based on the detected rotation of the dial sleeve 106. The processor 115 may include, for example, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.

[0122] The dose measurement system 101 further includes one or more computer-readable storage media. In the present embodiment, the computer-readable storage media include memory units 116A, 116B, including a program memory 116A and a main memory 116B, which can store software executed by the processor 115 .

[0123] The dose measurement system 101 further includes a battery 109 configured to supply power to the dose measurement system 101 .

[0124] The dose measurement system 100 further includes an output terminal 117. The output terminal 117 may be for transmitting the dose to the patient via a wireless network such as Wi-Fi or ) a wireless communication interface for communicating with another device; or an interface for a wired communication link, such as a receptacle for receiving a Universal Serial Bus (USB), mini USB, or micro USB connector.

[0125] In the present embodiment, the sensor 114 is a mechanically actuated switch 114. In one specific embodiment, the sensor 114 is a C&K(TM) HDT0001 switch.

[0126] In some embodiments, when the formation 112 engages the switch 114 during rotation of the dial sleeve 106 , the switch 114 moves from one of the on state or the off state to the other of the on state or the off state.

[0127] The sensor 114 includes a sensing member 118 configured to move from an unactuated state to an actuated state when the sensing member 118 is engaged by one of the formations 112 during rotation of the dial sleeve 106. The sensor 114 is configured to detect movement of the sensing member 118 between the unactuated state and the actuated state. The sensing member 118 may be a pivoting member 118 that rotates when the sensing member 118 is engaged by one of the formations 112 during rotation of the dial sleeve 106.

[0128] In some embodiments, each formation 112 includes a leading edge 112A arranged such that the leading edge 112A of each formation 112 sequentially abuts the sensor 114 when the dial sleeve 106 rotates in the first rotational direction X. In some embodiments, during rotation of the dial sleeve 106, engagement of the sensor 114 with the leading edge 112A of a first formation in the formations 112 to engagement of the sensor 114 with the leading edge 112A of an adjacent second formation in the formations 112 represents one encoding cycle.

[0129] In some embodiments, the sensor 114 is activated for between 40% and 60% of the encoding period. Preferably, the sensor 114 is activated for about 50% of the encoding period. When the dial sleeve 106 is rotated in the first rotational direction X during the dispensing process of the medicament, the sensor 114 is activated for 50% of the angular position of the dial sleeve 106 in one full rotation, and the sensor 114 is not activated for the remaining 50% of the angular position of the dial sleeve 106.

[0130] In some embodiments, the drug delivery device 100 includes a torque limiter (not shown). The sensor 114 is mounted to the dose setting dial 108 via the torque limiter, so that rotation of the dose dial 108 relative to the housing 102 at a torque greater than a predetermined limit causes the torque limiter to move to an open state, causing the dose setting dial 108 to rotate relative to the sensor 114. Optionally, the torque limiter includes an overload clutch (not shown).

[0131] As explained above, in some embodiments, axially pressing the dose setting dial 108 relative to the housing 102 disengages the clutch 105 to allow the dial sleeve 106 and the drive sleeve 107 to rotate relative to the housing 102 and the dose setting dial 108. In some embodiments, with the dose setting dial 108 depressed and the clutch 105 in a disengaged state, a user may grasp the dial sleeve 106 and overcome the force of the drive mechanism to rotate the dial sleeve in the second rotational direction relative to the dose setting dial 108. Such unintended operation of the device 100 may result in damage to the device 100. In particular, the sensing member 118 of the sensor 114 may be shaped and arranged to detect the rotation of the dial sleeve 106 relative to the dose setting dial 108 in the first rotational direction, i.e., such that the sensing member 118 moves on the formation 112 without agitation. Conversely, if the dial sleeve 106 is forced in the second rotational direction relative to the dose setting dial 108 , this may cause the formation 112 of the dial sleeve 106 to interfere with the sensing member 118 of the sensor 114 , which may result in damage to the sensing member 118 or misalignment of the sensing member 118 relative to the formation 112 .

[0132] In some embodiments, the drug delivery device 100 includes a one-way mechanism (not shown). The one-way mechanism can be configured to mitigate the above situation.

[0133] In one embodiment, the sensor 114 is mounted to the dose setting dial 108 via a one-way mechanism, such that rotation of the sensor 114 relative to the dose setting dial 108 is resisted by the one-way mechanism. Thus, under normal operating conditions, when the clutch 105 is disengaged and the dial sleeve 106 is rotated in the first rotational direction X during medicament dispensing, the formation 112 moves on the sensing member 114 and the sensing member 114 is held stationary by the one-way mechanism, such that relative rotation of the formation 112 and the sensing member 114 can be detected.

[0134] The one-way mechanism is configured to allow the sensor 114 to rotate relative to the dose setting dial 108 in the second rotational direction. Thus, in the unintended operating scenario discussed above where the user disengages the clutch 105 and then forces the dial sleeve 106 in the second rotational direction, the formation 112 will be urged against the sensing member 118 and will urge the sensor 114 to also rotate in the second rotational direction. The one-way mechanism allows the sensor 114 to rotate in the second rotational direction, and thus the sensor 114 will rotate relative to the dose setting dial 108 in the second rotational direction together with the dial sleeve 106, and thus will not force the formation 112 over the sensing member 118, and thus will prevent damage to the sensing member 118 and / or formation 112. In some embodiments, the one-way mechanism may include ratchet teeth on one or both of the dose setting dial 108 and the sensor 114.

[0135] The sensor 114 is mounted to the dose setting dial 108 such that axial movement of the dose setting dial 108 relative to the housing 102 to operate the dispensing mechanism 104 to dispense the medicament also axially moves the sensor 114. More specifically, the sensor 114 moves from a rest position (shown in FIG. 3 ) in which the sensor 114 is spaced apart from the formations 112 in the axial direction of the medicament delivery device 100 to a detection position (shown in FIG. 4 ) in which the sensor 114 moves distally such that rotation of the dial sleeve 106 causes each formation 112 to be detected by the sensor 114 such that the sensor 114 detects the rotation of the dial sleeve 106. In the present embodiment where the sensor 114 comprises a mechanical switch 114, when the sensor 114 is in the detection position, the formations 112 are physically engaged with the sensor 114 as the dial sleeve 106 rotates in the first rotational direction X.

[0136] The drug delivery device 100 further includes an activation switch 119 that can be moved from an initial closed state (shown in FIG. 3 ) to an open state to activate the dose measurement system 101 when the dose setting dial 108 is actuated. For example, movement of the activation switch 119 to the open state can cause one or more of the sensors 114, the processor 115, or other components of the dose measurement system 101 to wake up or power on.

[0137] In the present embodiment, the start switch 119 is mounted to the dose setting dial 108 such that the start switch 119 moves with the dose setting dial 108 such that the start switch 119 is urged against a component of the drug delivery device 100 (e.g., the drive sleeve 107) to move the start switch 119 to an on state.

[0138] In another embodiment (not shown), the activation switch 119 is mounted to a component of the pharmaceutical device 100 other than the dose setting dial 108, wherein sliding movement of the dose setting dial 108 during actuation causes the dose setting dial 108 or a portion connected to the dose setting dial 108 to be urged against the activation switch 119 to move the activation switch 119 to the on state. For example, the activation switch 119 may be mounted to the proximal end of the drive sleeve 107.

[0139] The sensor 114 and the activation switch 119 are configured such that when the user slides the dose setting dial 108 in the distal direction to actuate the dose setting dial 108, the activation switch 119 reaches the on state before the sensor 114 reaches the detection position. This helps to ensure that the dose measurement system 101 has time to be powered on before the sensor 114 reaches the detection position to detect the rotation of the dial sleeve 106. Thereby, the measurement accuracy of the dose dispensed by the dispensing mechanism 104 is increased.

[0140] The skilled person will recognize that many different types of start switches 119 may be used, for example, relays, analog switches, pressure sensors, push switches or flick switches. In one embodiment, the start switch 119 comprises a Panasonic (TM) ESE13 switch.

[0141] In the present embodiment, the activation switch 119 comprises a pivoting member 120 which pivots from a closed state to an open state to activate the dose measuring system 101. The pivoting member 120 is pivotally connected to the dose setting dial 108.

[0142] The activation switch 119 is configured to engage a portion of the drug delivery device 100 when the dose setting dial 108 is moved axially to operate the dispensing mechanism 104, such that the activation switch 119 is urged to the on state. In some embodiments, the portion comprises a portion of the dispensing mechanism 104, for example, the drive sleeve 107. In some embodiments where the activation switch 119 comprises a pivoting member 120, the pivoting member 120 engages with the portion of the drug delivery device 100 when the dose setting dial 108 is moved axially, such that the pivoting member 120 rotates relative to the dose setting dial 108 from the off state to the on state.

[0143] In some embodiments, the drug delivery device 100 includes a stopper 122, and wherein the activation switch 119 is configured to rest on the stopper 122 when the activation switch 119 is in the closed state.

[0144] In some embodiments, the drug delivery device 100 includes a support member 121. The support member 121 protrudes axially from the dose setting dial 108 in the distal direction. The support member 121 is generally cylindrical and is configured to be received in a hole of the drive sleeve 107. When the dose setting dial 108 is actuated, the support member 121 moves into the drive sleeve 107. The support member 121 can be attached to the dose setting dial 108 or formed integrally with the dose setting dial. In one embodiment, the support member 121 is mounted to the start switch 119.

[0145] Optionally, the support member 121 includes a stop 122 against which the start switch 119 abuts when the start switch 119 is in the off state. The stop 122 may be in the form of a stop surface 122 of the support member 121. In the present embodiment, the pivot member 120 abuts the stop surface 122 when the start switch is in the off state. During actuation of the actuator 109, the pivot member 120 rotates away from the stop surface 122 when the pivot member 120 is urged against the drive sleeve 107. Once the start switch 119 reaches the on state, the pivot member 120 may be further rotated to accommodate additional axial movement of the dose setting dial 108 in the distal direction relative to the housing 102, so that the dose measurement system 101 remains powered. In other embodiments, the activation switch 119 need only be moved briefly to the on state to power on the dose measurement system 101 , after which time the dose measurement system 101 will remain powered until the battery is depleted or for a set period of time regardless of the subsequent position of the activation switch 119 .

[0146] In some embodiments, the activation switch 119 is configured such that the activation switch 119 moves a first distance D1 from the off state to the on state (as illustrated in FIG. 3 ), and the sensor 114 is configured such that the sensor 114 moves a second distance D2 from the rest position to the detection position (as illustrated in FIG. 3 ). The second distance D2 is greater than the first distance D1 such that the activation switch 119 reaches the on state before the sensor 114 reaches the detection position. The dose setting dial 108 must be axially moved the first distance D1 to move the activation switch 119 to the on state, and must be axially moved the second distance D2 to move the sensor 114 to the detection position. Both the first distance D1 and the second distance D2 may extend in the axial direction of the drug delivery device 100.

[0147] 3, once the pivot member 120 is urged against the dial sleeve 107, the start switch 119 moves from the closed state to the open state to power the processor. However, it will be appreciated that in alternative embodiments (not shown), the pivot member 120 is partially or fully rotated after abutting the dial sleeve 107 before the start switch 119 is moved to the open state and the processor is powered. The point at which the start switch 119 moves to the open state is the switching point of the start switch 119.

[0148] Similarly, in FIG3 , when the sensing member 118 overlaps one of the structures 112 in the axial direction of the device 100, the sensor 114 moves from the rest position to the detection position, so that if the sensor 114 is aligned in the rotational direction with the structure 112, the sensing member 118 will begin to rotate and this is detected by the processor. However, it should be recognized that in alternative embodiments (not shown), before this movement is detected, the sensing member 118 partially or completely rotates after abutting the structure 112, and this position of the sensing member 118 is the switching point of the sensing member 118. In other words, the detection position of the sensor 114 can be a position where the switching point of the sensing member 118 is aligned axially with the structure 112.

[0149] Upon axial movement of the dose setting dial 108 , the switching point of the activation switch 119 is reached before the switching point of the sensor 114 .

[0150] In some embodiments, the dose setting dial 108 must be moved axially a third distance D3 (as shown in FIG. 3 ) to operate the dispensing mechanism 104 to dispense the medicament, for example, to disengage the clutch 105. The third distance D3 can be greater than the first distance D1 and the second distance D2 to help ensure that the medicament is not dispensed from the reservoir until the activation switch 119 has been moved to the on state and the sensor 114 has moved to the detection position.

[0151] In some embodiments, the support member 121 is rotatably coupled to a component of the drug delivery device 100 via a first support 125 and a second support 126. The first support 125 and the second support 126 may be radial supports. However, it should be appreciated that one of the first radial support 125 and the second radial support 126 may be omitted.

[0152] In the present embodiment, the support member 121 is rotatably coupled to the coupling member 127 via the first support 125 and the second support 126. However, it will be appreciated that in other embodiments, the coupling member 127 is omitted.

[0153] The first support 125 includes a curved inner surface 121A of the support member 121 and a curved outer surface 127A of the coupling member 127. The inner surface 121A and the outer surface 127A may be cylindrical. The inner surface 121A and the outer surface 127A may extend circumferentially around the longitudinal axis of the drug delivery device 100.

[0154] The inner surface 121A and the outer surface 127A are joined to form a first radial bearing 125 such that the support member 121 can rotate relative to the coupling member 127 , wherein the inner surface 121A of the support member 121 slides on the outer surface 127A of the coupling member 127 .

[0155] The second support 126 includes a circumferentially extending groove 121B of the support member 121 and a rib 127B of the coupling member 127. The rib 127B is received in the groove 121B. The rib 127B and the groove 121B form a second radial support 126 so that the support member 121 can rotate relative to the coupling member 127, wherein the rib 127B rotates in the groove 121B. In some embodiments, the engagement of the rib 127B and the groove 121B axially retains the support member 121 and the coupling member 127 relative to each other.

[0156] It will be appreciated that in alternative embodiments (not shown), the support member 121 may include grooves that receive ribs of the coupling member 127 to form the second bearing 126 .

[0157] The coupling member 127 is rotationally fixed relative to the dial sleeve 106. The coupling member 127 may be slidably mounted to the sleeve 106 such that the coupling member 127 is axially movable with the dose setting dial 108 during actuation. For example, the coupling member 127 may be slidably mounted on a longitudinal member that extends distally from the coupling member 127 and is connected to an inner portion of the drug delivery device 100. In another embodiment, the coupling member 127 is mounted to the clutch 105 such that actuation of the dose setting dial 108 axially urges the coupling member 127, which in turn axially urges the clutch 105 to disengage.

[0158] Optionally, the device 100 further includes a pivot 128. In FIG. 14 , the pivot 128 is shown in the form of a pivot point 128A, including a rounded protrusion 128A extending proximally from the proximal end of the coupling member 127 (the pivot point 128A is not shown in FIG. 13 ). The protrusion 128A abuts a generally flat distally facing surface of the support member 121. In an alternative embodiment (not shown), the rounded protrusion is disposed on the distally facing surface of the support member 121 and abuts the proximally facing surface of the coupling member 127.

[0159] The pivot 128 is configured to allow rotation of the dose setting dial 108 relative to the coupling member 127 (e.g., due to rotation of the coupling member 127 relative to the dose setting dial 108 during the dispensing process of the medicament). The pivot 128 helps to minimize the contact surface area between the support member 121 and the coupling member 127, and thus reduce the friction between them.

[0160] The pivot 128 is configured such that if the user exerts a force on the dose setting dial 108 that urges the dose setting dial 108 to tilt relative to the housing 102, for example by exerting an off-center force at the peripheral edge of the dose setting dial 108, the dose setting dial 108 will be urged to tilt about the pivot 128. However, the first radial support 125 and the second radial support 126 are configured to resist said tilting of the dose setting dial 108, and thus the radial supports 125, 126 help maintain the dose setting dial 108 aligned with the housing 102.

[0161] In more detail, it is desirable to prevent tilting of the dose setting dial 108 relative to the housing 102, which tilting may otherwise cause misalignment of the sensor 114 relative to the structure 112. For example, if the user presses on the edge of the dose setting dial 108 during actuation, this may cause the dose setting dial 108 to be urged to tilt relative to the longitudinal axis of the drug delivery device 100, so that the proximal end of the dose setting dial 108 is no longer perpendicular to the longitudinal axis and is now angled thereto instead. To help prevent this, the second support 126 is located distally of the first support 125. Therefore, if the user exerts a force on the dose setting dial 108 that causes the dose setting dial 108 to tilt, the second support 126 will provide a reaction force that prevents the dose setting dial 108 from tilting. The second support 126 being spaced apart from the pivot 128 means that the reaction force required for the second support 126 to stabilize the dose setting dial 108 and prevent tilting is less than if the second support 126 were located closer to the pivot 128.

[0162] The second support 126 may be located radially outward of the first support 125, in other words, further away from the longitudinal axis of the drug delivery device 100 than the first support 125. That is, the second support 126 may have a larger diameter than the first support 125. Therefore, if the dose setting dial 108 rotates while tilting, the reaction torque applied by the first support 125 is reduced compared to if the first support 125 has a larger diameter. This reduces the friction that resists the rotation of the dose setting dial 108. The second support 126 has a larger diameter than the first support 125 to provide support when the dose dial arrangement 108 is tilted about the pivot 128.

[0163] Optionally, the support member 121 or another component may include the aforementioned stopper 122 against which the activation switch 119 abuts when in the closed state.

[0164] The operation of the drug delivery device 100 will now be described. The user dials in a dose to be delivered by rotating the dose setting dial 108 relative to the housing 102 in a second rotational direction, which causes a corresponding rotation of the dial sleeve 106 relative to the housing 102 in the second rotational direction until the desired dose is displayed in a dose window (not shown). A needle (not shown) is inserted into the patient's injection site.

[0165] To deliver a dose of medicament, the user pushes the dose setting dial 108 axially in the distal direction into the housing 102. This causes the sensor 114 and the activation switch 119 mounted to the dose setting dial 108 to move axially in the distal direction. The axial movement of the dose setting dial 108 first causes the activation switch 119 to abut the drive sleeve 107, so that the activation switch 119 moves to the on state and thus the processor 115 of the dose measurement system 101 is powered on.

[0166] Continued movement of the dose setting dial 108 in the distal direction causes the sensor 114 to move to the detection position, wherein the sensor 114 overlaps the formation 112 in the axial direction of the drug delivery device 100, and then operates the dispensing mechanism 104 to discharge the drug from the reservoir for delivery via the needle. For example, the drug delivery device 100 may include a release mechanism that is activated to release the drive member when the dose setting dial 108 has moved distally to an axial position where the sensor 114 is in the detection position, or in other embodiments, when the dose setting dial 108 has moved further distally to the axial position (e.g., moved a third distance D3).

[0167] In the present embodiment, movement of the dose setting dial 108 relative to the housing 102 by the third distance D3 causes the clutch 105 to disengage, so that the clutch 105 moves to the disengaged position. Thus, the dial sleeve 106 and the drive sleeve 107 are allowed to rotate relative to the housing 102 and the dose setting dial 108 in the first rotational direction X under the force of the drive member to dispense the medicament from the reservoir. In another embodiment (not shown), the clutch 105 is disengaged when the dose setting dial 108 has moved the second distance D2 relative to the housing 102 while the sensor 114 reaches the detection position.

[0168] The sensor 114 detects rotation of the dial sleeve 106 relative to the housing 102 in the first rotational direction X during the dispensing process of the medicament, so that the processor 115 can determine the dose delivered by the medicament delivery device 100. In particular, the rotation of the dial sleeve 106 causes the one-by-one formations 112 to be urged against the sensing member 118, so that the sensing member 118 repeatedly moves between the unactuated state (shown in FIG. 8 ) and the actuated state (shown in FIG. 9 ).

[0169] The processor 115 is configured to determine the delivered dose based on the movement of the sensing member 118. For example, the processor 115 can be configured to count the number of times the sensing member 118 transitions from the non-actuated state to the actuated state and / or the number of times the sensing member 118 transitions from the actuated state to the non-actuated state. The memories 116A, 116B can be programmed with information or instructions that allow the processor 115 to convert the number of transitions into the delivered dose.

[0170] When the dial sleeve 106 rotates in the first rotational direction X, a portion of the leading edge 112A of the first formation 112 will abut the sensing member 118 and push the sensing member 118 from the unactuated state to the actuated state, causing the sensor 114 to transition from outputting a LOW signal to outputting a HIGH signal. This indicates the beginning of the first encoding region 123 and the end of the second encoding region 124. As the dial sleeve 106 continues to rotate in the first rotational direction X, the formation 112 will remain engaged with the sensing member 118, causing the sensing member 118 to remain in the actuated state. As the formation 112 begins to pass the sensor 114, the sensing member 118 will begin to move back toward the unactuated state while still engaging with the formation 112. In some embodiments, the sensing member 118 is biased into the unactuated state by a biasing member (not shown, such as a spring).

[0171] With further rotation of the dial sleeve 106 in the first rotational direction X, the sensing member 118 will reach the unactuated state and thus the sensor 114 will transition from outputting a high signal to outputting a low signal. This indicates the end of the first encoded region 123 and the beginning of the second encoded region 124. The sensor 114 will then align with the gap 113 adjacent to the formation 112 and thus the sensing member 118 will remain in the unactuated state and thus the sensor 114 will output a low signal until the dial sleeve 106 rotates to a position in which a portion of the leading edge 112A of the second formation 112 adjacent to the first formation 112 abuts the sensing member 118 and pushes the sensing member 118 from the unactuated state to the actuated state, causing the sensor 114 to transition from outputting a low signal to outputting a high signal again.

[0172] Rotation of the dial sleeve 106 in the first rotational direction X thus causes the sensor 114 to generate an oscillating signal, for example a square wave signal. The signal is input to the processor 115. The processor 115 may then use edge detection to determine the angular displacement of the dial sleeve 106 and thereby determine the dose dispensed from the medicament reservoir.

[0173] Movement of the sensing member 118 between the unactuated state and the actuated state is depicted in FIGS. 10 and 12 , which show schematic illustrations of the sensor 114 and the configuration 112 .

[0174] The dial sleeve 106 includes a plurality of first encoded regions 123 and a plurality of second encoded regions 124 alternately arranged around the rotation axis of the dial sleeve 106. Each first encoded region 123 starts when the sensing component 118 is pushed into an actuated state by a corresponding formation 112 adjacent to the sensing component 118, causing the sensor 114 to transition to output a high signal; and ends when the formation 112 passes the sensor 114, causing the sensing component 118 to move back to an unactuated state and the sensor 114 to transition to output a low signal. Each second encoded region 124 starts at a rotation position of the dial sleeve 106 in which the sensing component 118 reaches an actuated state in which the sensor 114 outputs a low signal; and ends when the sensing component 118 is pushed into an unactuated state by an adjacent formation 112 adjacent to the sensing component 118, causing the sensor 114 to output a high signal.

[0175] The sensor 114 is therefore able to distinguish between the first coding region 123 and the second coding region 124 because when the sensor 114 is aligned with the first coding region 123, the sensing component 118 is in an unactuated state and the sensor 114 outputs a high signal (or in an alternative embodiment, a low signal), and when the sensor 114 is aligned with the second coding region 124, the sensing component 118 is in an actuated state and the sensor 114 outputs a low signal (or in the alternative embodiment, a high signal).

[0176] Each first encoded region 123 subtends a predetermined angle around the rotational axis of the dial sleeve 106, and each second encoded region 124 subtends the same predetermined angle around the rotational axis of the dial sleeve 106. This does not necessarily mean that the formations 112 subtend the same angle around the rotational axis of the dial sleeve 106 as the gaps 113 between the formations 112. This is because the arrangement of the sensing member 118 and the formations 112 is such that the sensing member 118 remains in the actuated state even when the apex 112B of the formations 112 passes the apex 118A of the sensing member 118. For example, the trailing edge 112C of the formation 112, which generally faces in a circumferential direction opposite to the leading edge 112A, may still abut the sensing member 118 to prevent the sensing member 118 from returning to the non-actuated state. This is referred to as "ON drag", and refers to the relative movement required of the engaged formation 112 and sensor 114 before the sensing member is again transformed into the non-actuated state once the sensing member 118 has been transformed into the actuated state. In one embodiment, the formation 112 and the sensing member 118 are arranged so that the engaged formation 112 must move 1 mm relative to the sensing member 118 before the sensing member 118 transitions back to the unactuated state. Once engaged and moved to the actuated state by the formation 112, the sensing member 118 remains in the actuated state for 1 mm of travel of the formation 112.

[0177] In some embodiments, the size and / or shape of each formation 112 is adjusted to account for the opening resistance, such that the size of the first encoded region 123 and the second encoded region 124 remain equal. For example, the angle subtended by each formation 112 about the rotational axis of the dial sleeve 106 can reduce the size of the opening resistance (shown by arrow D4 in Figures 11 and 12).

[0178] In some alternative embodiments (not shown), the sensor 114 outputs a high signal when the sensing member 118 is in the unactuated state, and outputs a low signal when in the actuated state. In yet other embodiments, the sensor 114 outputs an analog signal that depends on the position of the sensing member 118, for example, a signal that is below a predetermined value when the sensing member 118 is in the unactuated state and above a predetermined value when in the actuated state. In some embodiments, the signal is generally sinusoidal when the dial sleeve 106 rotates in the first rotational direction X.

[0179] In one embodiment, processor 115 is configured to determine the dose dispensed from the reservoir by counting the number of low-to-high transitions and high-to-low transitions of the signal output by sensor 114. In some embodiments, this involves edge counting of the signal generated by sensor 114, e.g., positive and / or negative edge counting.

[0180] The processor 115 is thus able to determine the rotational displacement of the dial sleeve 106 during the delivery of the medicament with a resolution equal to the angle subtended by each of the first coded region 123 and the second coded region 124 about the rotational axis of the dial sleeve 106. From this rotational displacement, the processor 115 can determine the amount of medicament dispensed from the reservoir. The smaller the angle subtended by each of the first coded region 123 and the second coded region 124 about the rotational axis, the greater the resolution of the dose determination measurement.

[0181] The processor 115 can be configured to transmit the determined dosage of the medicament and, if determined, timestamp information to another device, such as a computer (not shown). As described above, the output 117 can be configured to transmit information using a wireless communication link. Alternatively, the dose measurement system 101 can be connected to a computer (not shown) using a wired connection (not shown) to allow information to be uploaded to the computer. The processor 115 can be configured to periodically transmit information to the computer. In some embodiments, the dose measurement system 115 can be used to monitor compliance with a specific dosage regimen.

[0182] In the present embodiment, the dial sleeve 106 comprises twenty-four formations 112. Thereby, twenty-four first encoded regions 123 and twenty-four second encoded regions 124 are provided. Each encoded region 123, 124 subtends an angle of 7.5 degrees about the rotation axis of the dial sleeve 106.

[0183] Referring now to FIGS. 16A to 18 , another embodiment of a dose measurement system 201 is shown. The dose measurement system 201 is similar to the dose measurement system 101 described above with respect to the embodiment of FIGS. 2 to 15 , wherein similar features retain the same reference numerals, and is part of a drug delivery device (not shown) having the same features as FIGS. 2 to 15 . However, the dose measurement system 201 differs in that it has a first sensor 214A and a second sensor 214C. The dial sleeve 206 includes a plurality of formations 212 separated by gaps 213, wherein the formations 212 are configured to engage the first sensor 214A and the second sensor 214C when the dial sleeve 206 is rotated.

[0184] Each of the first sensor 214A and the second sensor 214C can be of the same type as the sensor 114 of the embodiments described above with respect to Figures 2 and 15, having a sensing member 218A, 218C movable between an unactuated state and an actuated state, and therefore a detailed description will not be repeated below.

[0185] As in the embodiments of Figures 2 and 15, the dial sleeve 206 includes a plurality of first coded regions 223 and a plurality of second coded regions 224 arranged alternately around the rotation axis of the dial sleeve 206. The first coded regions 223 are formed by a portion of the corresponding structure 212, which, when aligned with the sensing member 218A, 218C, pushes the sensing member to the actuated state. The second coded regions 224 are formed between the first coded regions 223.

[0186] Each of the first sensor 214A and the second sensor 214C generates a high signal when the sensor 214A, 214C is aligned with one of the first coded regions 223, and generates a low signal when aligned with one of the second coded regions 224. Thus, each sensor 214A, 214C is able to distinguish between the first coded region 223 and the second coded region 224 and generate a signal accordingly.

[0187] The first sensor 214A and the second sensor 214C are offset such that, in use, rotation of the dial sleeve 206 in the first rotational direction X causes one of the first encoder regions 223 to align with the first sensor 214A, while one of the second encoder regions 224 to align with the second sensor 214C. Furthermore, further rotation of the dial sleeve 206 in the first rotational direction X causes one of the second encoder regions 224 to align with the first sensor 214A, while one of the first encoder regions 223 to align with the second sensor 214C. Thus, when the first sensor 214A detects one of the first encoder regions 223, the second sensor 214C will align with one of the second encoder regions 224, and when the second sensor 214C detects one of the first encoder regions 223, the first sensor 214A will align with one of the second encoder regions 224.

[0188] The relative positions of the first sensor 214A and the second sensor 214C relative to the first coded region 223 and the second coded region 224 are depicted in the schematic diagram of Figure 16A. In Figure 16A, the first sensor 214A is aligned with the first coded region 223, and therefore the first sensing member 218A will be in an actuated state, but this is not shown in order to give a clearer indication of the respective positions of the sensors 214A, 214C relative to the coded regions 223, 224.

[0189] In FIG. 16A , the configuration 212 and the gap 213 are schematically shown for illustrative purposes, and FIG. 16A is provided to illustrate the arrangement of the first encoding region 223 and the second encoding region 224 relative to the sensors 214A, 214C.

[0190] The first sensor 214A and the second sensor 214C may be arranged such that for all rotational positions of the dial sleeve 206 in which the first sensor 214A is aligned with one of the first coded regions 223, the second sensor 214C is aligned with one of the second coded regions 224. Thus, during rotation of the dial sleeve 206, when the sensing member 218A of the first sensor 214A transitions from the non-actuated state to the actuated state, the sensing member 218C of the second sensor 214C transitions from the actuated state to the non-actuated state.

[0191] In some embodiments, the first sensor 214A and the second sensor 214C are offset in the first rotational direction X about the axis of rotation of the drive sleeve 206 by 165 degrees.

[0192] The first sensor 214A and the second sensor 214C may be arranged such that for all rotational positions of the dial sleeve 206 in which the first sensor 214A is aligned with one of the second coded regions 224, the second sensor 214C is aligned with one of the first coded regions 223. Thus, during rotation of the dial sleeve 206, when the sensing member 218A of the first sensor 214A transitions from an actuated state to a non-actuated state, the sensing member 218C of the second sensor 214C transitions from a non-actuated state to an actuated state.

[0193] A processor (not shown) is configured to determine the delivered dose based on the movement of the first sensing member 218A and the second sensing member 218C. For example, the processor can be configured to count the number of times the sensing members 218A, 218C transition from the non-actuated state to the actuated state and / or the number of times the sensing members 218A, 218C transition from the actuated state to the non-actuated state. The processor can be preprogrammed with information that allows the processor to convert the number of transitions into a determination of the dose delivered by the drug delivery device.

[0194] In one embodiment, the processor is configured to determine the delivered dose based on one of the following: counting the transition of the sensing members 218A, 218C from the unactuated state to the actuated state; or counting the transition of the sensing members 218A, 218C from the second position to the unactuated state. Figure 17 shows such an example, in which the processor is configured to count the number of times the signals 219A, 219C output from the first sensor 214A and the second sensor 214C are respectively converted from low to high. This can be referred to as positive edge counting. In another example, the processor is configured to count the number of times the signals 219A, 219C output from the first sensor 214A and the second sensor 214C are converted from high to low. This can be referred to as negative edge counting.

[0195] Providing a first sensor 214A and a second sensor 214C offset in a first rotational direction X advantageously means that the resolution of the dose determination is increased compared to an embodiment having only a single sensor. In this embodiment, the resolution for a given size of the configuration 212 is doubled compared to an embodiment having only a single sensor. Thus, the size of the configuration 212 can be increased, and therefore the angle of each of the first encoding region 223 and the second encoding region 224 can be increased, resulting in a larger edge tolerance as explained below, while achieving the same resolution as a single sensor configuration. For example, if a first sensor 214A and a second sensor 214C are used, the number of configurations 212 can be reduced to twelve while achieving the same measurement resolution as the twenty-four configuration 112 embodiments of Figures 2 to 15.

[0196] Providing twelve configurations 212 means that each of the first encoded region 223 and the second encoded region 224 subtends an angle of 15 degrees about the axis of rotation of the dial sleeve 206. If only a single sensor 114 were utilized, and the processor counted only one of the negative or positive edges, the resolution of the measurement would be 30 degrees, which is the angle that the dial sleeve 206 would need to rotate for successive transitions of the signal output by the sensor from high to low (or low to high in a negative edge counting embodiment). However, because the first sensor 214A and the second sensor 214C are used, the resolution is doubled, making it the same as a single sensor embodiment with twenty-four configurations. However, an advantage of using fewer, larger configurations 212 (e.g., twelve configurations 212 in the present embodiment, although the skilled person will recognize that a different number of configurations 212 may be used) is that a greater edge tolerance is achieved.

[0197] The edge tolerance is the maximum distance the dial sleeve 206 must be rotated (in either the first rotational direction X or the second rotational direction Y) to align the sensor 214A, 214C with the transition between one of the first encoded regions 223 and one of the second encoded regions 224. Thus, in this embodiment, with twelve configurations 212, the maximum edge tolerance is 7.5 degrees. For comparison, in an embodiment with a single sensor 114 and twenty-four configurations 112, the edge tolerance is 3.75 degrees.

[0198] A larger edge tolerance is advantageous because it reduces the likelihood of false edge detection by the sensors 214A, 214C that might otherwise occur due to mechanical tolerances. This is because for embodiments having a larger edge tolerance, the sensing members 218A, 218C are less likely to transition from one of the unactuated and actuated states to the other of the first and second positions for a given rotational displacement of the dial sleeve 206. Thus, for example, a small amount of "play" or accidental rotation of the dial sleeve 206 relative to the housing 202 is less likely to cause the first and second sensors 214A, 214C to transition between outputting low / high signals, which would otherwise result in erroneous edge detection by the processor and thus measurement errors.

[0199] In some embodiments, the edge tolerance is at least 5 degrees, at least 7 degrees, and preferably, the edge tolerance is at least 7.5 degrees.

[0200] In some embodiments, the first and second sensors 214A, 214C are mounted to a dose setting dial (not shown) such that the sensors 214A, 214C can be moved from a rest position to a detection position in a manner similar to that described with respect to the embodiments of FIGS. 2-15 .

[0201] The first sensor 214A and the second sensor 214C may be arranged such that for all rotational positions of the dial sleeve 206, one of the first sensor 214A and the second sensor 214C is aligned with the first coded region 223 and the other of the first sensor 214A and the second sensor 214C is aligned with the second coded region 224. This means that when the user actuates the dose setting dial 208 (not shown) such that the first sensor 214A and the second sensor 214C move to the detection position, one of the first sensor 214A and the second sensor 214C will engage with one of the formations 212 such that the sensing members 218A, 218C of the sensors 214A, 214C move to the actuated state and thus the signal output from the sensors 214A, 214C transitions from low to high (or in embodiments where the sensors output inverted signals, the other sensor outputs such a transition).

[0202] If such transitions are counted and used to determine the dose dispensed from the reservoir, the determined dose will be greater than the actual dose dispensed. To compensate for this, in some embodiments, the processor is configured to disregard the first detected low to high transition from the output of the sensors 214A, 214C, as this is caused by axial movement of one of the sensors 214A, 214C to the detection position. The processor considers the remaining low to high transitions to determine the dose dispensed, as these transitions are the result of rotation of the dial sleeve 206 during the medicament dispensing process, and not due to axial movement of the sensors 214A, 214C.

[0203] In some embodiments, the dial sleeve 206 includes a plurality of encoding periods 225, wherein each encoding period 225 includes one of the first encoding regions 223 and an adjacent second encoding region 224. In some embodiments, for a given rotational position of the dial sleeve 206, the first sensor 214A is aligned with a portion of one of the encoding periods 225, and the second sensor 214C is aligned with a different portion of one of the encoding periods 225. If each encoding period 225 is considered to have a hypothetical period of 360 degrees, i.e., the configuration 212 repeats every 360 degrees, the first sensor 214A and the second sensor 214C may be offset by 180 degrees of the encoding period 225.

[0204] In some embodiments, the offset angle of the first sensor 214A and the second sensor 214C about the rotational axis of the dial sleeve 206 is an odd integer multiple of the angle subtended by each first encoded region 223 about the rotational axis of the drive sleeve 206. For example, if the first encoded regions 223 subtend 15 degrees about the rotational axis, the offset angle may be 15 degrees, 45 degrees, 75 degrees, 105 degrees, 135 degrees, 165 degrees, 195 degrees, 225 degrees, 255 degrees, 285 degrees, 315 degrees, or 345 degrees.

[0205] In one such embodiment, the first sensor 214A and the second sensor 214C are offset by an angle that is eleven times the angle subtended by each first encoded region 223 about the rotational axis of the drive sleeve 206. The first sensor 214A and the second sensor 214C are offset about the rotational axis of the drive sleeve 206 by 165 degrees.

[0206] The processor can be configured to determine the dose dispensed from the medication reservoir based on the signal output from one of the first sensor 214A and the second sensor 214C and the inversion of the signal output from the other of the first sensor 214A and the second sensor 214C. In one embodiment shown in FIG. 18 , the processor is configured to determine the dose dispensed from the medication reservoir based on the superposition of the signal from one of the first sensor 214A and the second sensor 214C and the inversion of the signal from the other of the first sensor 214A and the second sensor 214C. In this particular embodiment, the superposition 220 of the inversion of the signal 219A output from the first sensor 214A and the signal 219C output from the second sensor 214C.

[0207] The superposition 220 may be calculated by adding the first signal 219A to the inverse of the second signal 219C.

[0208] The processor is configured to determine the dose dispensed from the medicament reservoir by comparing the overlay 220 to a first threshold 226 and a second threshold 227 that is greater than the first threshold 226. In one such embodiment, the processor counts the number of times the overlay 220 transitions from a value below the first threshold 226 to a value greater than the second threshold 227 and / or the number of times the overlay transitions from a value above the second threshold 227 to a value below the first threshold 226. This helps improve the accuracy of the dose determination by helping to filter out errors such as sensor noise and switch jitter. This is because if one of the first sensor 214A and the second sensor 214C gives an erroneous reading, this will not cause the overlay 220 to transition in a manner that is counted by the processor in the dose determination calculation.

[0209] In this embodiment, the processor counts the number of times the superposition 220 transitions from a value below the first threshold 226 to a value greater than the second threshold 227 and the number of times the superposition transitions from a value above the second threshold 227 to a value below the first threshold 226. This count is used to determine the dose dispensed from the reservoir. As previously described, in embodiments where the sensors 214A, 214C are moved axially on the actuator, the first count can be ignored.

[0210] The first threshold 226 may be such that the superposition 220 is below the first threshold 226 when the first sensor 214A is aligned with the second encoded portion 224 and the second sensor 214C is simultaneously aligned with the first encoded portion 223 and is above the first threshold 226 otherwise. That is, in order for the superposition 220 to be below the first threshold 226, both the inverse of the second signal 219C and the first signal 219A must be low.

[0211] The second threshold 227 may be such that the superposition 220 is above the second threshold 227 when the first sensor 214A is aligned with the first encoded portion 223 and the second sensor 214C is simultaneously aligned with the second encoded portion 224 and is otherwise below the second threshold 227. That is, in order for the superposition 220 to be above the second threshold 227, both the inverse of the second signal 219C and the first signal 219A must be high.

[0212] In some embodiments, when the overlay 220 is equal to or below the first threshold 226, the overlay 220 is in a low state L, and when the overlay 220 is equal to or above the second threshold 227, the overlay 220 is in a high state H. When the overlay 220 is above the first threshold 226 but below the second threshold 227, the overlay 220 is in an UNDEFINED state. The processor may count the number of times the overlay 220 transitions from the low state to the high state and / or from the high state to the low state to determine the dispensed dose.

[0213] For example, for certain rotational positions of the dial sleeve 206, the signal 219A output from the first sensor 214A should be high and the signal 219C output from the second sensor 214C should be low, so that the inverse of the signal 219C output from the second sensor 214C should be high, and thus two high signals mean that the superposition signal 220 should be above the second threshold 227 (the superposition 220 should be in a high state H). However, the mechanical switch of the first sensor 214A may momentarily "bounce", causing it to output a low reading. In such a situation, the superposition 220 will be below the second threshold 227 but will still be greater than the first threshold 226, because the inverse signal is still high (the superposition will be in an undefined state). The superimposed signal 220 will only transition to a value below the first threshold 226 and thus be counted by the processor to determine the dose dispensed when both the signal 219A output from the first sensor 214A and the inverse of the signal 219C output from the second sensor 214C are low (at which point the superimposed signal 220 will transition to the low state L, the total transition from high to low being counted as one increment by the processor in the dispensed dose determination). Thus, the switch bounce will not be counted by the processor in the dose dispense calculation and thus will not contribute to an erroneous dose determination value. Alternatively, if after the "bounce", the first sensor 214A instead outputs a high reading again, the superimposed signal 220 will transition back to the high state H, and this will not be counted as an increment by the processor because the superimposed signal was previously in the high state H before moving to the undefined state and thus has not yet transitioned from the low state L to the high state H.

[0214] In some embodiments, when the dial sleeve 206 has reached the zero position and has completed rotation such that the programmed dose has been dispensed from the reservoir, the first sensor 214A and the second sensor 214B will each align with a particular coded region 223, 224 for a period longer than the time the dial sleeve 206 rotates and the first and second sensors 214A, 214C align with the individual coded regions 223, 224. This is demonstrated in FIG. 18 , which shows that after the last transition (in the example of FIG. 18 , transition number 8) between the first and second coded regions 223, 224 detected by the sensors 214A, 214C during the rotation of the dial sleeve 206 occurs, the signals 219A, 219C output from the first and second sensors 223, 224 remain in the high and low states (and therefore the superposition 220 remains in the high state) for a longer period of time. In FIG. 18 , the last transition after transition number 8 is due to the actuator (in this case the dose setting dial 208 ) moving proximally away from its actuated position, causing the sensors 214A, 214C to move out of the detection position and back to the rest position and therefore no longer engage the formation 212 .

[0215] The processor may therefore determine that the dial sleeve 206 has stopped rotating, and therefore a dose has been dispensed, if the first sensor 214A and / or the second sensor 214C remains aligned with one of the first and second coded regions 223, 224 for more than a predetermined amount of time. The predetermined amount of time may be selected to be greater than the amount of time that either of the first and second coded regions 223, 224 will remain aligned with one of the first and second sensors 214A, 214C during rotation of the dial sleeve 206 during operation of the dispensing mechanism to dispense medicament from a reservoir.

[0216] If the processor determines that a dose has been dispensed, the processor may perform one or more operations, such as: indicating to a user that a dose has been dispensed, for example, via a user interface such as an LED, speaker, or screen or by transmitting a signal to display such information on a separate device; storing and / or transmitting data related to the dispensed dose; ignoring any additional transitions between the first and second coded regions detected by the sensor so that the additional transitions are not used to calculate the dispensed dose; and / or powering down the dose measurement system to save energy.

[0217] Referring now to FIGS. 16B , 19 and 20 , another embodiment of a dose measurement system 301 is shown. The dose measurement system 301 is similar to the dose measurement system 201 described above with respect to the embodiments of FIGS. 16A and 17 - 18 , with similar features retaining the same reference numerals, and is part of a drug delivery device (not shown) having the same features as FIGS. 2 - 15 . However, the dose measurement system 301 differs in that, in addition to including the first sensor 314A and the second sensor 314C, the dose measurement system 301 further includes a third sensor 314B and a fourth sensor 314D.

[0218] The dial sleeve 306 includes a plurality of formations 312 separated by gaps 313 , wherein the formations 312 are configured to engage a first sensor 314A, a second sensor 314C, a third sensor 314B, and a fourth sensor 314D when the dial sleeve 306 is rotated.

[0219] Each of the first sensor 314A, the second sensor 314C, the third sensor 314B and the fourth sensor 314D can be of the same type as the first sensor 214A and the second sensor 214C of the embodiments described above with respect to Figures 16A and 17 to 18, and respectively have a first sensing member 318A, a second sensing member 318C, a third sensing member 318B and a fourth sensing member 318D that can move between an unactuated state and an actuated state, and therefore the detailed description will not be repeated below.

[0220] As with the embodiments of FIG. 16A and FIG. 17 to FIG. 18 , the dial sleeve 306 includes a plurality of first coded regions 323 and a plurality of second coded regions 324 alternately arranged around the rotation axis of the dial sleeve 306. The first coded regions 323 are formed by a portion of the corresponding structure 312, which, when aligned with the sensing member 318A, 318C, 318B, 318D, pushes the sensing member to the actuated state. The second coded regions 324 are formed between the first coded regions 323.

[0221] Each of the first sensor 314A, the second sensor 314C, the third sensor 314B, and the fourth sensor 314D generates a high signal when the sensor 314A, 314C, 314B, 314D is aligned with one of the first coded regions 323, and generates a low signal when aligned with one of the second coded regions 324. Therefore, each sensor 314A, 314C, 314B, 314D is able to distinguish between the first coded region 323 and the second coded region 324 and generate a signal accordingly.

[0222] As with the embodiment of the dose measurement system 201 of FIGS. 16A and 17-18 , the first sensor 314A and the second sensor 314C are offset such that, in use, rotation of the dial sleeve 306 in the first rotational direction X causes one of the first encoder regions 323 to align with the first sensor 314A, while one of the second encoder regions 324 to align with the second sensor 314C. Furthermore, further rotation of the dial sleeve 306 in the first rotational direction X causes one of the second encoder regions 324 to align with the first sensor 314A, while one of the first encoder regions 323 to align with the second sensor 314C. Thus, when the first sensor 314A detects one of the first encoded regions 323, the second sensor 314C will align with one of the second encoded regions 324, and when the second sensor 314C detects one of the first encoded regions 323, the first sensor 314A will align with one of the second encoded regions 324.

[0223] The third sensor 314B and the fourth sensor 314D are offset from the first sensor 314A and the second sensor 314C in the rotational direction of the dial sleeve 306 .

[0224] In some embodiments, the first sensor 314A and the second sensor 314C are offset 165 degrees about the rotational axis of the drive sleeve 306 in the first rotational direction X. In some embodiments, the third sensor 314B is offset 90 degrees from the first sensor 314A about the rotational axis in the first rotational direction X, and wherein the fourth sensor 314D is offset 105 degrees from the third sensor 314A about the rotational axis in the second rotational direction.

[0225] In FIG. 16B , the configuration 312 and the gap 313 are schematically shown for illustrative purposes, and FIG. 16B is provided to show the arrangement of the first encoding region 323 and the second encoding region 324 relative to the sensors 314A, 314C, 314B, 314D.

[0226] The third sensor 314B is arranged such that, in use, rotation of the dial sleeve 306 in the first rotational direction X causes one of the first encoder regions 323 to align with the first sensor 314A, while another of the first encoder regions 323 is aligned with the third sensor 314B. Furthermore, further rotation of the dial sleeve 306 in the first rotational direction X causes one of the second encoder regions 324 to align with the first sensor 314A, while another of the second encoder regions 323 is aligned with the third sensor 314B. Thus, when the first sensor 314A detects one of the first encoder regions 323, the third sensor 314B will align with another of the first encoder regions 323, and when the first sensor 314A detects one of the second encoder regions 324, the third sensor 314B will align with another of the second encoder regions 324.

[0227] The third sensor 314B may be arranged such that for all rotational positions of the dial sleeve 306 in which the first sensor 314A is aligned with one of the first coded regions 323, the third sensor 314B is aligned with one of the first coded regions 323. Thus, during rotation of the dial sleeve 306, when the sensing member 318A of the first sensor 314A transitions from the non-actuated state to the actuated state, the sensing member 318B of the third sensor 314B transitions from the non-actuated state to the actuated state. Similarly, the third sensor 314B may be arranged such that for all rotational positions of the dial sleeve 306 in which the first sensor 314A is aligned with one of the second coded regions 324, the third sensor 314B is aligned with one of the second coded regions 324. Thus, during rotation of the dial sleeve 306 , when the sensing member 318A of the first sensor 314A transitions from the actuated state to the unactuated state, the sensing member 318B of the third sensor 314B transitions from the actuated state to the unactuated state.

[0228] The fourth sensor 314D is arranged such that, in use, rotation of the dial sleeve 306 in the first rotational direction X causes one of the first encoder regions 323 to align with the second sensor 314C, while another of the first encoder regions 323 is aligned with the fourth sensor 314D. Furthermore, further rotation of the dial sleeve 306 in the first rotational direction X causes one of the second encoder regions 324 to align with the second sensor 314C, while another of the second encoder regions 323 is aligned with the fourth sensor 314D. Thus, when the second sensor 314C detects one of the first encoder regions 323, the fourth sensor 314D will align with another of the first encoder regions 323, and when the second sensor 314C detects one of the second encoder regions 324, the fourth sensor 314D will align with another of the second encoder regions 324.

[0229] The fourth sensor 314D may be arranged such that for all rotational positions of the dial sleeve 306 in which the second sensor 314C is aligned with one of the first coded regions 323, the fourth sensor 314D is aligned with one of the first coded regions 323. Thus, during rotation of the dial sleeve 306, when the sensing member 318C of the second sensor 314C transitions from the non-actuated state to the actuated state, the sensing member 318D of the fourth sensor 314D transitions from the non-actuated state to the actuated state. Similarly, the fourth sensor 314D may be arranged such that for all rotational positions of the dial sleeve 306 in which the second sensor 314C is aligned with one of the second coded regions 324, the fourth sensor 314D is aligned with one of the second coded regions 324. Thus, during rotation of the dial sleeve 306 , when the sensing member 318C of the second sensor 314C transitions from the actuated state to the unactuated state, the sensing member 318D of the fourth sensor 314D transitions from the actuated state to the unactuated state.

[0230] In some embodiments, the dial sleeve 306 includes a plurality of encoding periods 325, wherein each encoding period 325 includes one of the first encoding regions 323 and an adjacent second encoding region 324. In some embodiments, for a given rotational position of the dial sleeve 306, the first sensor 314A is aligned with a portion of one of the encoding periods 325, and the second sensor 314C is aligned with a different portion of one of the encoding periods 325. If each encoding period 325 is considered to have a hypothetical period of 360 degrees, i.e., the configuration 312 repeats every 360 degrees, the first sensor 314A and the second sensor 314C may be offset by 180 degrees of the encoding period 325.

[0231] The third sensor 314B is in phase with the first sensor 314A, such that the sensors 314B, 314A are aligned with the same portion of the corresponding encoding period 325, and are therefore offset by zero degrees of the encoding period 325. The fourth sensor 314D is in phase with the second sensor 314C, such that the sensors 314D, 314C are aligned with the same portion of the corresponding encoding period 325, and are therefore offset by zero degrees of the encoding period 325.

[0232] If the first sensor 314A fails to detect the coded regions 323, 324 due to a detection error, the third sensor 314B provides redundancy and also allows filtering of impossible detection events. If the second sensor 314C fails to detect the coded regions 323, 324 due to a detection error, the fourth sensor 314D provides redundancy and also allows filtering of impossible detection events (please explain examples of such impossible detection events).

[0233] The processor can be configured to determine the dose dispensed from the medication reservoir based on the superposition of the inverse phases of the signals 319A, 319B output from the first sensor 314A and the third sensor 314B and the signals 319C, 319D output from the second sensor 314C and the fourth sensor 314D, or the superposition of the inverse phases of the signals 319C, 319D output from the second sensor 314C and the fourth sensor 314D and the signals 319A, 319B output from the first sensor 314A and the third sensor 314B.

[0234] In the particular embodiment shown in FIG. 20 , the dose is determined based on an inverse superposition 320 of signals 319A, 319B output from the first and third sensors 314A, 314B and signals 319C, 319D output from the second and fourth sensors 314C, 314D.

[0235] The superposition 320 may be calculated by adding the first signal 219A and the third signal 219B with the inverse of the second signal 219C and the fourth signal 219D.

[0236] The processor is configured to determine a dose to be dispensed from the medicament reservoir by comparing the overlay 320 to a first threshold 326 and a second threshold 327 that is greater than the first threshold 326 .

[0237] In one such embodiment, the processor counts the number of times the overlay 320 transitions from a value below the first threshold 326 to a value greater than the second threshold 327 and / or the number of times the overlay transitions from a value above the second threshold 327 to a value below the first threshold 326. This helps improve the accuracy of the dose determination by helping to filter out errors such as sensor noise and switch bounce. This is because if one or both of the sensors 314A, 314B, 314C, 314D give an erroneous reading, this will not cause the overlay 320 to transition in a manner that is counted by the processor in the dose determination calculation.

[0238] In this embodiment, the processor counts the number of times the superposition 220 transitions from a value below the first threshold 326 to a value greater than the second threshold 327 and the number of times the superposition transitions from a value above the second threshold 327 to a value below the first threshold 326. This count is used to determine the dose dispensed from the reservoir. As previously described, in embodiments where the sensors 314A, 314B, 314C, 314D are axially moved on an actuator that operates the activation switch 332, the first count may be disregarded. The signal 333 to activate the switch 332 is shown in FIG.

[0239] The first threshold 326 may be such that in order for the superposition 320 to be below the first threshold 326, at least three of the inverses of the signals 319A, 319B output from the first and third sensors 314A, 314B and the signals 319C, 319D output from the second and fourth sensors 314C, 314D must be low.

[0240] The second threshold 227 may be such that in order for the superposition 320 to be above the second threshold 326, at least three of the inverses of the signals 319A, 319B output from the first and third sensors 314A, 314B and the signals 319C, 319D output from the second and fourth sensors 314C, 314D must be high.

[0241] In some embodiments, when the overlay 320 is equal to or below the first threshold 326, the overlay 320 is in a low state L, and when the overlay 320 is equal to or above the second threshold 327, the overlay 320 is in a high state H. When the overlay 320 is above the first threshold 326 but below the second threshold 327, the overlay 320 is in an UNDEFINED state. The processor may count the number of times the overlay 320 transitions from the low state to the high state and / or from the high state to the low state to determine the dispensed dose.

[0242] For example, for certain rotational positions of the dial sleeve 306, the signals 319A, 319B output from the first sensor 314A and the third sensor 314C should be high, and the inverse of the signals 319C, 319D output from the second sensor 314B and the fourth sensor 314D should be high, and thus the four high signals mean that the superposition signal 320 should be equal to or above the second threshold 327 (the superposition 320 should be in the high state H). However, the mechanical switch of the first sensor 314A may momentarily "bounce", causing it to output a low reading. In such a situation, the superposition 320 is still equal to or above the second threshold 327, and thus the state of the superposition 320 will remain in the high state H. Therefore, the superposition 320 does not transition to the low state, and thus the processor does not count increments for the dispensed dose determination calculation. In fact, if the mechanical switch of the fourth sensor 314D also "bounces" at the same time so that it outputs a high reading and therefore the inversion of the signal 319D is low, the superposition 320 includes two low and two high signal inputs and therefore the superposition 320 will be greater than the first threshold 326 but less than the second threshold 327. The superposition 320 will therefore be in an undefined state U.

[0243] The superimposed signal 220 will transition to a value equal to or below the first threshold 226, and therefore be counted by the processor to determine the dispensed dose, only when at least three of the following occur: the first sensor 314A output signal 319A is low, the third sensor 314B output signal 319B is low, the second sensor 314C output signal 319C is high such that the inversion is low, and the fourth sensor 314D output signal 319D is high such that the inversion is low (at which point the superimposed signal 320 will transition to the low state L, and the total transition from high to low is counted by the processor as an increment in the dispensed dose determination).

[0244] Thus, in the dose dispensing calculation, multiple switch bounces or other such errors will not be counted by the processor and will therefore not contribute to erroneous dose determination values.

[0245] Referring now to FIGS. 16C to 21 , another embodiment of a dose measurement system 401 is shown. The dose measurement system 401 of FIG. 16C is similar to the dose measurement system 301 of the embodiments of FIGS. 16B , 19 , and 20 , with similar features retaining the same reference numerals. The differences are that the configuration 412 and gap 413 of the dial sleeve 406 have different sizes, and the first sensor 414A, the second sensor 414C, the third sensor 414B, and the fourth sensor 414D have different arrangements relative to the first coded region 423 and the second coded region 424.

[0246] The dial sleeve 406 includes half of the formations 412 and gaps 413 of the dial sleeve 306 of Figures 16B, 19 and 20. In the present embodiment, the dial sleeve 406 includes six formations 412 and six gaps 413.

[0247] As with the embodiments of FIGS. 16A and 17-18 and 16B and 19-20, the dial sleeve 406 includes a plurality of first coded regions 423 and a plurality of second coded regions 424 alternately arranged around the rotation axis of the dial sleeve 406. The first coded regions 423 are formed by a portion of the corresponding structure 412 that urges the sensing member 418A, 418C, 418B, 418D to an actuated state when aligned with the sensing member 418A, 418C, 418B, 418D. The second coded regions 424 are formed between the first coded regions 423.

[0248] Each of the first sensor 414A, the second sensor 414C, the third sensor 414B, and the fourth sensor 414D generates a high signal when the sensor 414A, 414C, 414B, 414D is aligned with one of the first coded regions 423, and generates a low signal when aligned with one of the second coded regions 424. Therefore, each sensor 414A, 414C, 414B, 414D is able to distinguish between the first coded region 423 and the second coded region 424 and generate a signal accordingly.

[0249] As with the embodiment of the dose measurement system 201 of FIGS. 16A and 17-18 and the embodiment of FIGS. 16B and 19-20 , the first sensor 414A and the second sensor 414C are offset such that, in use, rotation of the dial sleeve 406 in the first rotational direction X causes one of the first encoder regions 423 to align with the first sensor 414A, while a second encoder region 424 to align with the second sensor 414C. Furthermore, further rotation of the dial sleeve 406 in the first rotational direction X causes one of the second encoder regions 424 to align with the first sensor 414A, while a first encoder region 423 to align with the second sensor 414C. Therefore, when the first sensor 414A detects a first encoding region in the first encoding region 423, the second sensor 414C will be aligned with a second encoding region in the second encoding region 424, and when the second sensor 414C detects a first encoding region in the first encoding region 423, the first sensor 414A will be aligned with a second encoding region in the second encoding region 424.

[0250] The third sensor 414B and the fourth sensor 414D are offset from the first sensor 414A and the second sensor 414C in the rotational direction of the dial sleeve 406. In FIG16C , the configuration 412 and the gap 413 are schematically shown for illustrative purposes, and FIG16C is provided to show the arrangement of the first encoded region 423 and the second encoded region 424 relative to the sensors 414A, 414C, 414B, 414D.

[0251] In some embodiments, the first sensor 414A and the third sensor 414B are offset 165 degrees about the rotational axis of the drive sleeve 406 in the first rotational direction X. In some embodiments, the second sensor 414C is offset 90 degrees about the rotational axis from the first sensor 414A in the first rotational direction X, and wherein the fourth sensor 414D is offset 105 degrees about the rotational axis from the fourth sensor 414A in the second rotational direction.

[0252] The third sensor 414B is arranged such that when the dial sleeve 406 is rotated, such that when the first sensor 414A is aligned with the transition between the coded regions 423, 424 and the second sensor 414C is aligned with the transition between the coded regions 423, 424, the third sensor 414B is not aligned with the transition between the coded regions 423, 424 (i.e., the third sensor 414B is aligned with only one of the first coded region 423 or the second coded region 424). In some embodiments, when the dial sleeve 406 is in such a position, the third sensor 414B is equidistant from the two nearest transitions between the first coded region 423 and the second coded region 424.

[0253] The fourth sensor 414D is arranged such that when the dial sleeve 406 is rotated, such that when the first sensor 414A is aligned with the transition between the coded regions 423, 424 and the second sensor 414C is aligned with the transition between the coded regions 423, 424, the fourth sensor 414D is not aligned with the transition between the coded regions 423, 424 (i.e., the fourth sensor 414D is aligned with only one of the first coded region 423 or the second coded region 424). In some embodiments, when the dial sleeve 406 is in such a position, the fourth sensor 414D is equidistant from the two nearest transitions between the first coded region 423 and the second coded region 424.

[0254] The third sensor 414B and the fourth sensor 414D are offset such that, in use, rotation of the dial sleeve 406 in the first rotational direction X causes one of the first encoder regions 423 to align with the third sensor 414B, while one of the second encoder regions 424 to align with the fourth sensor 414D. Furthermore, further rotation of the dial sleeve 406 in the first rotational direction X causes one of the second encoder regions 424 to align with the third sensor 414B, while one of the first encoder regions 423 to align with the fourth sensor 414D. Thus, when the third sensor 414B detects one of the first encoder regions 423, the fourth sensor 414D will align with one of the second encoder regions 424, and when the fourth sensor 414D detects one of the first encoder regions 423, the third sensor 414B will align with one of the second encoder regions 424.

[0255] In some embodiments, when the first sensor 414A is aligned with the transition between the coding regions 423, 424, the second sensor 414C is aligned with the transition between the coding regions 423, 424, and wherein when the third sensor 414B is aligned with the transition between the coding regions 423, 424, the fourth sensor 414D is aligned with the transition between the coding regions 423, 424.

[0256] In some embodiments, the dial sleeve 306 includes a plurality of encoding periods 425, wherein each encoding period 425 includes one of the first encoding regions 423 and an adjacent second encoding region 424. In some embodiments, for a given rotational position of the dial sleeve 406, the first sensor 414A, the second sensor 414C, the third sensor 414B, and the fourth sensor 414D are each aligned with a different portion of the corresponding encoding period 425.

[0257] If each encoding period 425 is considered to have an imaginary period of 360 degrees, i.e., configuration 412 repeats every 360 degrees, first sensor 414A and second sensor 414C may be offset by 180 degrees of encoding period 425. Third sensor 414B and fourth sensor 414D may be offset by 180 degrees of encoding period 425.

[0258] In some embodiments, the third sensor 414B may be offset 90 degrees relative to one of the first sensor 414A and the second sensor 414C, and 270 degrees relative to the other of the first sensor 414A and the second sensor 414C. The fourth sensor 414B may be offset 270 degrees relative to the one of the first sensor 414A and the second sensor 414C, and 90 degrees relative to the other of the first sensor 414A and the second sensor 414C.

[0259] In this embodiment, the third sensor 414B is offset 270 degrees relative to the first sensor 414A and 90 degrees relative to the second sensor 414C. The fourth sensor 414D is offset 90 degrees relative to the first sensor 414A and 270 degrees relative to the second sensor 414C.

[0260] Since the first sensor 414A, the second sensor 414C, the third sensor 414B and the fourth sensor 414D are all out of phase with respect to each other, the processor is able to determine whether the dial sleeve 406 is rotating in the first rotational direction or the second rotational direction. As the dial sleeve 406 rotates, only one of the sensors 414A, 414C, 414B, 414D is aligned with the positive edge transition from the first encoded region 423 to the second encoded region 424.

[0261] For example, if the dial sleeve 406 is rotated in the first rotational direction X, the actuation will have the following order: first sensor 414A, third sensor 414B, second sensor 414C, and then fourth sensor 414D. That is, one of the configurations 212 will abut the sensing member 418A of the first sensor 414A to move the sensing member 418A from the unactuated state to the actuated state; one of the configurations 212 will abut the sensing member 418B of the third sensor 414B to move the sensing member 418B from the unactuated state to the actuated state; one of the configurations 212 will abut the sensing member 418C of the second sensor 414C to move the sensing member 418C from the unactuated state to the actuated state; and then, one of the configurations 212 will abut the sensing member 418D of the fourth sensor 414D to move the sensing member 418D from the unactuated state to the actuated state.

[0262] In contrast, if the dial sleeve 406 is rotated in the second rotational direction, the actuation will have the following order: the first sensor 414A, the fourth sensor 414D, the second sensor 414C, and then the third sensor 414B. That is, one of the configurations 212 will abut the sensing member 418A of the first sensor 414A to move the sensing member 418A from the unactuated state to the actuated state; one of the configurations 212 will abut the sensing member 418D of the fourth sensor 414D to move the sensing member 418D from the unactuated state to the actuated state; one of the configurations 212 will abut the sensing member 418C of the second sensor 414C to move the sensing member 418C from the unactuated state to the actuated state; and then, one of the configurations 212 will abut the sensing member 418B of the third sensor 414B to move the sensing member 418D from the unactuated state to the actuated state.

[0263] Thus, the processor may determine the rotational direction of the dial sleeve 406 based on the order of actuation of the sensors 414A, 414B, 414C, 414D. In some embodiments, the determination of the rotational direction may be made starting from any one of the sensors 414A, 414B, 414C, 414D. For example, if the second sensor 414C is actuated, the processor may determine that the dial sleeve 406 is rotating in the first rotational direction X if the next actuation is the fourth sensor 414D, and may determine that the dial sleeve 406 is rotating in the second rotational direction if the next actuation is the third sensor 414B.

[0264] The processor may be configured to disregard the detected rotation of the dial sleeve 406 from the dispensed dose determination if it is determined that the rotation is in the second rotational direction. For example, when the dial sleeve 406 is rotated in the first rotational direction X during the dispensing of the medicament, the dial sleeve 406 will reach the "zero" position once the dial sleeve 406 has been fully rotated in the first rotational direction X and all doses have been dispensed. However, it has been found that once the dial sleeve 406 reaches the "zero" position, the dial sleeve 406 may rotate slightly past the "zero" position and may then rotate back again in the second rotational direction (which may be referred to as "backspin"), which may cause another of the sensors 414A, 414B, 414C, 414D to be actuated. If this further rotation is taken into account when calculating the dispensed dose, the measurement will be higher than the actual dose delivered. However, due to the rotation of the dial sleeve in the second rotational direction, the rotation may be disregarded from the calculation. During rotation of the dose setting dial 408, the dial sleeve 406 may also be moved in a second rotational direction to "dial in" a dose.

[0265] It should be noted that in an alternative embodiment (not shown), one of the third sensor 414B and the fourth sensor 414D is omitted. In such an arrangement, the processor is still able to determine the rotational direction of the dial sleeve 406 based on the readings from the three remaining sensors.

[0266] In the above embodiments, the sensors 114, 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D are mechanically actuated. However, it will be appreciated that in some embodiments, different types of sensors are used. In an alternative embodiment shown in FIG. 22 , the dose measurement system comprises one or more light sensors 514. The or each light sensor 514 may comprise a light shutter. The dial sleeve 506 may comprise a plurality of configurations 512 separated by gaps 513. As the dial sleeve 506 rotates, the configurations 512 align with the light shutter one by one to interrupt the light beam of the light shutter, so that the sensors 514 detect the rotation of the dial sleeve 506. In an embodiment having a plurality of sensors 514, the sensors 514 may be arranged as described above with reference to any one of FIGS. 16A to 16C .

[0267] In other embodiments (not shown), the sensors 114, 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D, 514 may be, for example, magnetic sensors or capacitive sensors. For example, in one embodiment (not shown), the first encoded region may comprise a plurality of portions of magnetic material adhered to the proximal end of the dial sleeve and spaced apart about the axis of rotation of the dial sleeve, the second encoded region being formed as a space between adjacent portions of the magnetic material. The or each sensor comprises a magnetic sensor, for example a Hall sensor, that detects the presence of magnetic material. In yet another embodiment (not shown), the first encoded region may comprise a plurality of portions of reflective material adhered to the proximal end of the dial sleeve and spaced apart about the axis of rotation of the dial sleeve, the second encoded region being formed as a space between adjacent portions of the reflective material, or alternatively formed as a portion of a material having different optical properties than the first encoded region (such as being less reflective). The or each sensor may comprise an optical sensor which can distinguish between optical properties of the first and second encoded regions.

[0268] In the above embodiment, the dose setting dial 108 forms an actuator that is axially movable relative to the housing to operate the dispensing mechanism to dispense the medicament from the reservoir. However, in an alternative embodiment (not shown), the actuator alternatively includes a component that can be moved relative to the dose setting dial to dispense the medicament. In one embodiment (not shown), the actuator includes a push button that is mounted to the dose setting dial and can slide axially relative to the dose setting dial to operate the dispensing mechanism to dispense the medicament from the reservoir. In operation, the push button is configured to move axially a short distance relative to the housing and the dial sleeve. This movement occurs when the user applies force on the push button. For example, the user pushes the push button axially in the distal direction toward the injection site. This axial movement of the push button disengages the clutch, so that the clutch moves to the disengaged position, and thus allows the dial sleeve and the drive sleeve to rotate relative to the housing and the dose setting dial in a first rotational direction under the force of the drive member to dispense the medicament from the reservoir. The push button can be located at the proximal end of the dose setting dial. The push button can be biased toward the proximal side. In some embodiments, the sensor 114, 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D, 514 is mounted to a push button to move relative to the housing and the dose setting dial. The sensor can move from a rest position to a detection position when the push button is actuated, which can also cause the start switch to be actuated to an on state to power the dose measurement system, similar to what was previously described. The start switch can reach the on state before the sensor reaches the detection position.

[0269] In some alternative embodiments (not shown), the sensor 114, 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D, 514 does not move axially with the actuator. The sensor can be in the detection position before the actuator is actuated. In some embodiments (not shown), the sensor is fixed relative to the housing.

[0270] In the above embodiments, the coded region is provided on the dial sleeve 106 , 206 , 306 , 406 , 506 and the or each sensor 114 , 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D, 514 is configured to detect rotation of the dial sleeve 106 , 206 , 306 , 406 , 506 . However, in alternative embodiments (not shown), the coded region (e.g., configuration and gap) is disposed on the drive sleeve 107, and the or each sensor 114, 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D, 514 is configured to detect rotation of the drive sleeve 107. In yet other embodiments (not shown), the coded region is disposed on another component, and the or each sensor 114, 214A, 214B, 214C, 214D, 314A, 314B, 314C, 314D, 414A, 414B, 414C, 414D, 514 is configured to detect rotation of the component. In some embodiments (not shown), the component is a component of a dispensing mechanism.

[0271] In some embodiments (not shown), one or more of the signals 219A, 219C, 319A, 319B, 319C, 319D, 419A, 419B, 419C, 419D output from the sensor are filtered to improve measurement accuracy by, for example, filtering noise from the signal. In some embodiments, the signal is filtered by a low pass filter. In some embodiments, the signal is filtered before being input to the processor. In other embodiments, the processor filters the signal.

[0272] Electromechanical switches include electrical contacts that can oscillate for a short time after being turned on or off. This can result in several fast signal pulses after the original signal edge, which is called jitter. Jitter can be reduced by switches with oscillation-minimizing contact designs. Further, as described above, the signal can be filtered by electronics or software as long as the jitter duration is shorter than the regular signal pulse duration. This filtering is called debouncing.

[0273] It would be advantageous to improve power management so that smaller batteries with smaller capacities could be used, resulting in smaller dose measurement systems. Reducing peak current is advantageous because small batteries are more sensitive to peak current.

[0274] Improved power management can include reducing energy consumption during storage. In one such embodiment (not shown), the battery is mechanically disconnected by a strip (e.g., a paper or plastic strip) during storage. The user can pull the strip to activate the dose measurement system. In another embodiment (not shown), the battery is mechanically disconnected by a mechanism. When the actuator is pressed for the first time, the component is disconnected and a permanent connection between the electronic device and the battery is enabled. In yet another embodiment (not shown), the battery is mechanically disconnected by a life switch on the PCB. This activation can be irreversible. In yet another embodiment, the electronic device remains in a strong power saving mode until the actuator is pressed for the first time. In yet another embodiment (not shown), the battery is inserted into the device only before first use. In some embodiments (not shown), the button can be replaced or recharged.

[0275] The processor may have a minimum sampling interval. In some embodiments, the shortest gap is about 700 μs. In such an embodiment, a sampling interval of 500 μs is sufficient to properly detect such short gaps. In such an embodiment, the minimum sampling frequency to detect all signal edges is calculated as:

[0276]

[0277] In Equation 1, fmin is the minimum sampling frequency, and T is the sampling interval. Therefore, for a sampling interval of 500 μs, the minimum sampling frequency is 2 kHz.

[0278] Using mechanical switches instead of light gates / barriers reduces energy consumption because, in some embodiments, the state of a mechanical switch can be detected with less than 100 μA per switch. If the signal is of good quality, additional energy can be saved by detecting the edge of each interrupt. This means that the switch can be connected to an interrupt port of the processor. The interrupt port can be selected to be triggered by a rising / falling edge in the switch state, thereby allowing the processor to wait in a low energy state instead of performing a permanent energy expensive polling operation at a high sampling frequency.

[0279] In an embodiment where a shutter / barrier is used, during an estimated sampling period of 500 μs, the IR-LED can be turned on (rise time typically 10 μs @ ≤ 100 kΩ, same for sink), the ADC can acquire (2 μs) and convert (5 μs), and the rest of the time the IR-LED can be turned off to save power.

[0280] This has been found to reduce power.

[0281] In some embodiments (not shown), the drug delivery device includes a user interface, such as one or more LEDs that prompt a user or provide an indication to a user. The user interface can be optimized to reduce power consumption. For example, if multiple LEDs of one color are used for a specific prompt or indication, the number of LEDs of that color can be reduced. In some embodiments, the LED power is reduced. In some embodiments, an injection reminder function is removed, such as a reminder alarm. In some embodiments, a residence time indication (e.g., a visual or audible indication of the amount of time the drug delivery device should remain in place after an injection) is removed. In some embodiments, an end-of-life mode (e.g., an indicator that the dose measurement system and / or drug delivery device has reached the end of its operating life) is removed. In some embodiments, the user interface is omitted.

[0282] In some embodiments, the BLE (Bluetooth(TM) Low Energy) announcement duration is reduced. The announcement time defines how long the drug delivery device attempts to connect to a mobile phone or other device. This parameter is important when the mobile phone is often out of reach (e.g. too far away or turned off). Experiments have shown that 5 seconds are sufficient when the mobile phone is within a suitable reachable radio range. Therefore, the announcement time can be reduced from 15 seconds to about 5 seconds. This means that the announcement energy can be increased by 3 times.

[0283] In some embodiments, the BLE communication timeout is reduced. The communication channel currently remains open for 3 seconds after data transmission. This can be improved when a mobile phone or other device sends an explicit communication shutdown command to the drug delivery device and the timeout is left only as an inefficient operation.

[0284] In some embodiments, the number of communication attempts per day is reduced. Data can be transmitted to the mobile phone after an injection, but only if the last data transmission before that exceeds a predetermined time period (e.g., 12 hours). In some embodiments, the startup log data is never transmitted separately. This helps save energy for users who have several injections and / or priming doses per day.

[0285] There may be use cases where the user wants to force an immediate data transfer. This can be initiated by a button press pattern. One more step is to only transmit after a specific button press pattern (e.g., pressing an actuator or another button five times in rapid succession, or long pressing a button a certain number of times). In some embodiments, data is transmitted after a normal button release event, but only if the last data transmission was more than a predetermined time period (e.g., 12 hours) before that. In some embodiments, pre-fill data is not transmitted separately. For example, if the user performs a pre-fill operation in which the processor detects one or two rotational increments, this is not transmitted separately to the dose delivery data (in some embodiments, pre-fills (e.g., measurements equal to or less than two rotational increments) are ignored and not transmitted).

[0286] Avoiding or reducing current peaks is advantageous because they reduce the available capacity of the battery. Therefore, it is advantageous to optimize the energy management for UI, sensor and communication current peaks. In some embodiments, the current peaks of the electronic components are aligned continuously. In some embodiments, components with high current are not active at the same time as components with high peak current, or at least such simultaneous occurrence is minimized.

[0287] Visible LEDs may have high peak currents, but the timing is controllable. BLE communications may have high peak currents, which may not be controllable or predictable. Therefore, in some embodiments, communication begins only after potential user feedback of the LEDs has been completed.

[0288] The radio range may depend on the transmit power of the dose measurement system (e.g., a system on chip (SoC) component). Reducing the power will reduce the average and peak currents. In some embodiments, the maximum output power is +0 dBm and has a peak current of 5.3 mA. If the maximum output power is instead +4 dBm, the peak current will be 7.5 mA, which may be too high for smaller battery types. Reducing the output power to -4 dBm results in a peak current of 4.2 mA.

[0289] In some embodiments, the battery is a CR1225 button cell with a nominal capacity of 48 mAh.

[0290] While the above embodiments have been described with respect to collecting data from an insulin injection pen, it should be noted that embodiments of the present invention may be used for other purposes, such as monitoring the injection of other medicaments.

[0291] The injection device may include a cartridge containing a liquid drug or medicament. In an example, by pressing an injection button, a portion of it may be discharged from the cartridge according to a dialed or preset amount. The term "drug" or "medicament" may refer to a pharmaceutical formulation comprising at least one pharmaceutically active compound. More details about specific pharmaceutical formulations may be obtained from the disclosure of co-pending application PCT / EP2018 / 082640, attorney docket number DE2017 / 081, which, to the extent possible, should be incorporated herein by reference.

[0292] Those skilled in the art will appreciate that various modifications (additions and / or removals) may be made to the various components of the materials, formulations, apparatuses, methods, systems, and embodiments described herein without departing from the overall scope and spirit of the invention, and that the invention encompasses such modifications and any and all equivalents thereof.

Claims

1. A dose measurement system (201, 301, 401) for a drug delivery device (100), wherein the drug delivery device comprises a drug reservoir and a dispensing mechanism (104) operable to dispense a drug from the drug reservoir, the dispensing mechanism (104) comprising a component configured to rotate during drug dispensing, the component comprising a plurality of first encoder regions (223, 323, 423) and a plurality of second encoder regions (224, 324, 424), the dose measurement system comprising: a first sensor (214A, 314A, 414A) and a second sensor (214C, 314C, 414C), the first sensor and the second sensor being offset such that, in use, rotation of the component causes a first one of the first encoder regions (223, 323, 423) to align with the first sensor (214A, 314A, 414A) while a second one of the second encoder regions (224, 324, 424) to align with the second sensor (214C, 314C, 414C), and then a second one of the second encoder regions (224, 324, 424) to align with the first sensor (214A, 314A, 414A) while a first one of the first encoder regions (223, 323, 423) to align with the second sensor (214C, 314C, 414C), the first sensor and the second sensor being configured to distinguish between the first encoder region and the second encoder region to detect rotation of the component; as well as A processor (115) is configured to determine a dose to be dispensed from the medicament reservoir based on the detected rotation of the component.

2. The dose measurement system (201, 301, 401) of claim 1, wherein the component comprises a plurality of configurations (212, 312, 412), wherein each first encoder region (223, 323, 423) comprises at least a portion of a corresponding configuration detectable by the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C) when the component is rotated, wherein the second encoder region (224, 324, 424) is disposed between adjacent first encoder regions (223, 323, 423).

3. The dose measurement system (201, 301, 401) of claim 2, wherein each formation (212, 312, 412) comprises teeth, wherein each first encoder region (223, 323, 423) comprises at least a portion of a corresponding tooth detectable by the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C) when the component is rotated, and wherein each second encoder region (224, 324, 424) comprises at least gaps between adjacent teeth.

4. The dose measurement system according to claim 1 , wherein the first sensor and the second sensor are arranged such that for all rotational positions of the component in which the first sensor is aligned with one of the first encoder areas, the second sensor is aligned with one of the second encoder areas.

5. The dose measurement system (201, 301, 401) of any one of claims 1 to 3, wherein the component comprises a plurality of encoding periods (225, 325, 425), wherein each encoding period comprises a first encoder region of the first encoder regions (223, 323, 423) and an adjacent second encoder region (224, 324, 424), wherein for a given rotational position of the component, the first sensor (214A, 314A, 414A) is aligned with a portion of one of the encoding periods and the second sensor (214C, 314C, 414C) is aligned with a different portion of one of the encoding periods.

6. The dose measurement system (401) of claim 5, further comprising a third sensor (414B) aligned with a portion of one of the encoding periods (225, 325, 425) different from the first sensor (414A) and the second sensor (414C) when the component is in the given rotational position.

7. The dose measurement system (401) of claim 6, further comprising a fourth sensor (414D) that is aligned with a portion of one of the encoding periods (225, 325, 425) that is different from the first sensor (414A), the second sensor (414C), and the third sensor (414B) when the component is in the given rotational position.

8. The dose measurement system (301) according to any one of claims 1 to 3, further comprising a third sensor (314B), the third sensor being configured such that, in use, when the component is rotated, the third sensor (314B) is aligned with a first one of the first encoder areas (223, 323, 423) at the same time as the first sensor (314A) is aligned with a first one of the first encoder areas (223, 323, 423).

9. The dose measurement system (301) of claim 8, further comprising a fourth sensor (314D), the fourth sensor being configured such that, in use, when the component is rotated, the fourth sensor (314D) is aligned with a first one of the first encoder areas (223, 323, 423) at the same time as the second sensor (314C) is aligned with a first one of the first encoder areas (223, 323, 423).

10. The dose measurement system (301) of claim 8, wherein when the first sensor is aligned with a transition between the first encoder region and the second encoder region, the third sensor is also aligned with a transition between the first encoder region and the second encoder region.

11. The dose measurement system (301) of claim 9, wherein when the second sensor is aligned with a transition between the first encoder region and the second encoder region, the fourth sensor is also aligned with a transition between the first encoder region and the second encoder region.

12. The dose measurement system (201, 301, 401) according to any one of claims 1 to 3, wherein each of the first encoder region (223, 323, 423) and the second encoder region (224, 324, 424) extends over the same predetermined angle around the rotation axis of the component.

13. The dose measurement system (201, 301, 401) according to claim 12, wherein the predetermined angle is 15 degrees or 30 degrees.

14. The dose measurement system (201, 301, 401) of claim 12, wherein the second sensor (214C, 314C, 414C) is offset from the first sensor (214A, 314A, 414A) in a first direction about the rotation axis by an odd integer multiple of an angle subtended by each first encoder region (223, 323, 423) about the rotation axis.

15. The dose measurement system (201, 301, 401) of claim 14, wherein the second sensor (214C, 314C, 414C) is offset from the first sensor (214A, 314A, 414A) by 165 degrees in a first direction about the rotation axis.

16. A dose measurement system (201, 301, 401) according to claim 1, wherein each of the first encoder area and the second encoder area includes a length extending in the rotational direction of the component, wherein the dose measurement system includes a third sensor, the third sensor is offset from the first sensor and the second sensor, so that in use when the first sensor is aligned with one of the first encoder areas and the second sensor is aligned with one of the second encoder areas, the third sensor is aligned with a different portion of the length along one of the first encoder area and the second encoder area.

17. The dose measurement system (201, 301, 401) of any one of claims 1 to 3, wherein the processor (115) is configured to determine a dose dispensed from the medicament reservoir by a process comprising counting a number of transitions between the first encoder region (223, 323, 423) and the second encoder region (224, 324, 424) detected by the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C).

18. A dose measurement system (201, 301, 401) according to any one of claims 1 to 3, wherein the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C) are configured to move from an idle position to a detection position, wherein movement of the sensors to the detection position causes one of the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C) to align with one of the first encoder areas (223, 323, 423), and wherein the processor (115) is configured such that when determining the dispensed dose, the processor (115) compensates for the alignment when the sensors move to the detection position.

19. The dose measurement system (201, 301, 401) of any one of claims 1 to 3, wherein the processor (115) is configured to determine a dose dispensed from the medicament reservoir based on a signal from one of the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C) and an inverted signal from the other of the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C).

20. The dose measurement system (201, 301, 401) of claim 19, wherein the processor (115) is configured to determine a dose dispensed from the medicament reservoir based on a superposition of the signal from one of the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C) and the inverted signal from the other of the first sensor (214A, 314A, 414A) and the second sensor (214C, 314C, 414C).

21. The dose measurement system (201, 301, 401) of claim 20, wherein the processor (115) is configured to determine a dose dispensed from the medicament reservoir by comparing the superposition to a first threshold and a second threshold greater than the first threshold.

22. The dose measurement system (201, 301, 401) of claim 21, wherein the processor (115) is configured to determine a dose dispensed from the medicament reservoir by counting the number of times the superposition transitions from a value below the first threshold to a value greater than the second threshold and / or from a value above the second threshold to a value below the first threshold.

23. A drug delivery system comprising the dose measurement system of any one of claims 1 to 22.

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