Injection Device with a Preselector

Abstract

An injection device for setting and injecting a dose of a medicament comprises a housing) extending along an axial direction (z), a dose setting mechanism arranged in the housing, a dose dial displaceable relative to the housing for setting of the dose, a dose tracker (50; 150) operably connectable to the dose dial (12), the dose tracker is at least one of translationally or rotationally displaceable relative to the housing during setting of a dose, wherein a positional state of the dose tracker relative to the housing is indicative of a size of the dose, and a preselector configured to define a maximum dose positional state of the dose tracker relative to the housing, and a first marker provided on one of the dose tracker and the preselector and configured to indicate the positional state of the dose tracker relative to the preselector.

Claims

1. An injection device for setting and injecting a dose of a medicament, the injection device comprising: a housing; a dose setting mechanism arranged in the housing; a dose dial displaceable relative to the housing for setting of the dose; a dose tracker operably connectable to the dose dial, wherein the dose tracker is at least one of translationally displaceable or rotationally displaceable relative to the housing during setting of a dose, and wherein a positional state of the dose tracker relative to the housing is indicative of a size of the dose; a preselector configured to define a maximum dose positional state of the dose tracker relative to the housing; and a first marker provided on one of the dose tracker and the preselector and configured to indicate the positional state of the dose tracker relative to the preselector.

2. The injection device according to claim 1, wherein the preselector is configured to vary the maximum dose positional state of the dose tracker.

3. The injection device according to claim 1, wherein the preselector is at least one of translationally displaceable or rotationally displaceable relative to the housing between at least two preselection positional states, and wherein the preselector is lockable relative to the housing in any of the at least two preselection positional states.

4. The injection device according to claim 1, further comprising an indicator assembly configured to indicate when the dose tracker reaches the maximum dose positional state.

5. The injection device according to claim 4, wherein the first marker is located on the dose tracker, and wherein the indicator assembly is configured to reveal the first marker on the dose tracker when the dose tracker reaches the maximum dose positional state.

6. The injection device according to claim 4, wherein the indicator assembly is integrated into the preselector and comprises an aperture extending through the preselector, and wherein the first marker of the dose tracker is discernible through the aperture when the dose tracker reaches the maximum dose positional state.

7. The injection device according to claim 6, wherein the indicator assembly comprises a magnifying lens arranged in the aperture.

8. The injection device according to claim 1, wherein the dose tracker comprises at least one tracking stop feature, wherein the preselector comprises at least one preselector stop feature, and wherein the preselector stop feature is configured to engage with the at least one tracking stop feature to block and to prevent a displacement of the dose tracker beyond the maximum dose positional state.

9. The injection device according to claim 4, wherein the first marker is provided on the dose tracker, wherein a second marker is provided on the preselector, and wherein the indicator assembly is configured to determine the positional state of the dose tracker based on the first marker and to determine a preselection positional state of the preselector based on the second marker.

10. The injection device according to claim 9, wherein the indicator assembly is configured to compare the positional state of the dose tracker with the preselection positional state of the preselector.

11. The injection device according to claim 3, wherein the indicator assembly comprises a processor and an electronic display to: visualize at least one of the positional state of the dose tracker and a preselection positional state of the preselector; and/or visualize the positional state of the dose tracker relative to the preselection positional state of the preselector.

12. The injection device according to claim 11, wherein the indicator assembly comprises a communication unit connected to the processor to exchange electronic data with a remote electronic device.

13. The injection device according to claim 1, further comprising a piston rod and a cartridge comprising a barrel filled with a medicament.

14. An add-on device configured for attachment or coupling to an injection device for setting and injecting a dose of a medicament, the injection device comprising: a housing, a dose setting mechanism arranged in the housing, a dose dial displaceable relative to the housing for setting of the dose, a dose tracker operably connectable to the dose dial, wherein the dose tracker is at least one of translationally displaceable or rotationally displaceable relative to the housing during setting of a dose, and wherein a positional state of the dose tracker relative to the housing is indicative of a size of the dose, a preselector configured to define a maximum dose positional state of the dose tracker relative to the housing, and a first marker provided on one of the dose tracker and the preselector and configured to indicate the positional state of the dose tracker relative to the preselector; wherein the add-on device comprises: a remote indicator assembly configured to indicate a positional state of the dose tracker relative to the preselector.

15. The add-on device according to claim 14, wherein the remote indicator assembly comprises at least one of: a first position sensor configured to determine the positional state of the dose tracker, and a second position sensor configured to determine a preselection positional state of the preselector.

16. The add-on device according to claim 14, wherein the indicator assembly comprises a processor and an electronic display configured for: visualizing at least one of the positional state of the dose tracker and a preselection positional state of the preselector; and/or visualizing the positional state of the dose tracker relative to the preselection positional state of the preselector.

17. The injection device according to claim 13, wherein the barrel is sealed by a bung that is axially displaceable relative to the barrel by the piston rod.

18. The add-on device according to claim 14, wherein the injection device further a cartridge comprising a barrel filled with a medicament.

19. The add-on device according to claim 18, wherein the injection device further comprises a piston rod and wherein the barrel of the cartridge is sealed by a bung that is axially displaceable relative to the barrel by the piston rod.

20. The add-on device according to claim 14, wherein the preselector of the injection device is configured to vary the maximum dose positional state of the dose tracker.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0135] In the following, embodiments of the drive mechanism and the injection device are described in detail by making reference to the drawings, in which:

[0136] FIG. 1 is a schematic representation of the injection device comprising a dose tracker and a preselector,

[0137] FIG. 2 shows a configuration with the preselector in a first preselection positional state and the dose tracker in a first positional state and a corresponding configuration of the indicator assembly,

[0138] FIG. 3 corresponds to FIG. 2 with the dose tracker in the maximum dose positional state,

[0139] FIG. 4 is another configuration of the preselector in a second preselection positional state and the dose tracker in a first positional state smaller than the maximum dose positional state,

[0140] FIG. 5 corresponds to FIG. 4 with the dose tracker in the maximum dose positional state,

[0141] FIG. 6 shows another schematic example of an injection device,

[0142] FIG. 7 shows another example of the injection device connected or coupled with an add-on device,

[0143] FIG. 8 is a block diagram of an add-on device,

[0144] FIG. 9 is an exploded view of an injection device as handed out to a patient,

[0145] FIG. 10 is an exploded view of the components that make up the injection device according to FIG. 9,

[0146] FIG. 11 is a perspective view of another example of the injection device comprising a preselector and an indicator assembly,

[0147] FIG. 12 is a perspective enlarged view of the proximal end of the device according to FIG. 11,

[0148] FIG. 13 is a perspective illustration of the device according to FIGS. 11 and 12 with the housing partially cut away,

[0149] FIG. 14 is an isolated view of a preselector,

[0150] FIG. 15 is a longitudinal cut through the proximal end of the housing of the injection device according to FIGS. 11-13,

[0151] FIG. 16 is a side view of a proximal portion of the injection device with the preselector in a minimum preselection positional state,

[0152] FIG. 17 is the device according to FIG. 16 with the preselector in an intermediate preselection positional state, and

[0153] FIG. 18 is a side view of the injection device according to FIGS. 16 and 17 with the preselector in a maximum preselection positional state,

[0154] FIG. 19 is an isolated and perspective view of the dose tracker,

[0155] FIG. 20 is another example of a proximal end of an injection device comprising an electronically implemented indicator assembly in an initial configuration with the preselector in a minimum preselection positional state,

[0156] FIG. 21 is the device according to FIG. 20 with the dose tracker and the dose dial in the maximum dose positional state,

[0157] FIG. 22 is the device according to FIGS. 20 and 21 with the preselector in a maximum preselection positional state and with the dose dial and the dose tracker in a zero dose configuration,

[0158] FIG. 23 is another configuration of the device according to FIG. 22 with the dose tracker and the dose dialin a maximum dose positional state,

[0159] FIG. 24 is a perspective view of the injection device according to FIGS. 20-21 with the housing partially cut away,

[0160] FIG. 25 shows the indicator assembly of the device according to FIGS. 20-24 detached from the housing of the injection device,

[0161] FIG. 26 is another illustration of the injection device with the indicator assembly provided in an add-on device detached from the injection device,

[0162] FIG. 27 is a bottom view of the add-on device,

[0163] FIG. 28 is an enlarged illustration of the proximal portion of the device according to FIG. 24,

[0164] FIG. 29 shows the interaction between a first position sensor with the first marker on the dose tracker with the dose tracker in an initial configuration,

[0165] FIG. 30 represents another configuration of the position sensor according to FIG. 29 with the dose tracker in a first positional state,

[0166] FIG. 31 shows the dose tracker in a second positional state and

[0167] FIG. 32 shows the dose tracker in a third positional state.

DETAILED DESCRIPTION

[0168] The schematic illustration of an injection device 1 in accordance to FIG. 1 is rather simplified and is only used to reveal and show the mutual interaction between a dose dial, a dose tracker, a preselector and an indicator assembly of an injection device. The injection device 1 comprises a housing 10. The housing 10 may be an elongated housing and may extend in a longitudinal or axial direction (z). Inside the housing 10 there is typically provided a reservoir or a cartridge 6 configured to contain and to hold a liquid medicament. The housing 10 comprises a distal end 2 near a dispensing end of the cartridge 6. Opposite the distal end the cartridge 6 is provided with a bung 7 that seals an interior of the cartridge 6 in proximal direction. For expelling or dispensing of a dose of the medicament from the interior of the cartridge 6 the injection device 1 comprises a drive mechanism 8. The drive mechanism 8 comprises a piston rod 20 configured to exert a distally directed pressure to the bung and in order to drive the bung 7 in distal direction.

[0169] The injection device 1 also comprises a dose setting mechanism 9. The dose setting mechanism comprises at least a dose tracker 50. The dose tracker 50 is displaceable relative to the housing 10. It is at least one of translationally or rotationally displaceable relative to the housing 10 during setting of a dose. Typically and during dose dispensing under the action of the drive mechanism 8 the dose tracker 50 returns into a zero dose configuration. In a subsequent dose setting procedure the dose tracker 50 can be become repeatedly subject to at least one of a translational or rotational displacement relative to the housing 10. The displacement of the dose tracker 50 during setting of a dose is controllable or inducible by means of a dose dial 12 that is displaceable relative to the housing 10 for setting of the dose. For instance the dose dial 12 is rotationally supported on a proximal end of the housing 10.

[0170] Insofar the illustration of FIG. 1 does not reflect the relative positions of the various components of the injection device relative to each other. The injection device 1 further comprises a trigger 11 by way of which a dose dispensing action can be triggered and/or controlled after a dose of appropriate size has been set in a dose setting procedure. The trigger is operable engageable with the drive mechanism for dispensing or expelling of the dose.

[0171] In addition to the dose tracker 50 the injection device 1 comprises a preselector 70. The preselector 70 is configured to define a maximum dose positional state 55 of the dose tracker relative to the housing 10. The maximum dose positional state 55 is that positional state of the dose tracker 50 that is furthest away from a zero dose positional state of the dose tracker. The maximum dose positional state 55 defines the maximum sized dose of a medicament that can be dispensed with the injection device.

[0172] By means of the preselector 70 the maximum dose positional state 55 and hence the maximum dose to be dispensed with the injection device 1 can be varied and modified. Insofar the preselector 70 provides a limiter or is a limiter for the dose setting mechanism 9. The dose setting mechanism 9 and the dose tracker 50 may be originally configured and designed to provide a selection of doses of variable size. With the preselector 70 only one or a few predefined doses among a range of differently sized doses that could be originally dispensed with the injection device 1 are pre-set. Hence, by means of the preselector 70 the capability of the dose setting mechanism 9 to set and to select numerous differently sized doses is reduced to only one or a few differently sized doses of the medicament.

[0173] Insofar and by means of the preselector 70 the injection device 1 can be transformed or transferred into a kind of a fixed dose injection device. This is of particular benefit for situations where the user himself should not decide about the size of a dose of the medicament to be administered. From a user perspective the preselector therefore facilitates overall usage and handling of the injection device.

[0174] Typically, the preselector 70 and the dose tracker 50 are configured to mechanically engage. The dose tracker 50 may comprise at least one tracking stop feature 51 and the preselector may comprise at least one preselector stop feature 73. By means of the preselector stop feature 73 the preselector 70 mechanically engages with the correspondingly shaped tracking stop feature 51 of the dose tracker 50. In this way a displacement of the dose tracker 50 beyond the maximum dose positional 55 state can be blocked and prevented. The preselector 70 may be only operable by caregivers or medical staff. It may be protected against misuse and may not be operable or actuatable or reconfigurable by the end user or patient. However and according to an individual prescription schedule or medication schedule the care giver may individually modify or configure the preselector 70 so that the injection device becomes capable to dispense and to expel a dose of required size.

[0175] The injection device 1 further comprises an indicator assembly 90 by way of which at least a relative position of the dose tracker 50 relative to the preselector 70 can be indicated. Since the device 1 is limited to expel or to dispense only a single sized dose of known size the injection device 1 may be void of a specific dose indicating mechanism, e.g. illustrating the dose size in terms of units of the medicament, such as international units of insulin. It is not required for the indicator assembly 90 to visualize or illustrate a number of units of the medicament actually set. Since the injection device can be limited or restricted to the dispensing or expelling of multiple doses of equal size that particular size is known to at least the caregiver. It is hence sufficient for the patient when the indicator assembly has a limited function and is only capable to provide a comparison between the actual positional state 54 of the dose tracker compared to the predefined maximum dose positional state 55 of the dose tracker 50.

[0176] In FIG. 2 a configuration is illustrated wherein the preselector 70 is in a first preselection positional state 110. The length of the arrow representing the first preselection positional state 110 is indicative of the path length the dose dial 12 or the dose tracker 50 may be displaced starting from a zero dose configuration until reaching a maximum dose positional state 55. In the configuration according to FIG. 2 the momentary positional state 54 of the dose tracker 50 is also illustrated. This arrow is shorter than the arrow representing the first preselection positional state 110. Accordingly, the indicator assembly 90 as shown in FIG. 2 provides an indication 91 that the maximum dose positional state 55 has not yet been reached. For example the indication 91 is illustrated as a curved arrow indicating to a user of the injection device to dial the dose dial 12 further in a dose incrementing direction, e.g. clockwise.

[0177] In the configuration according to FIG. 3 the dose dial 12 and hence the dose tracker 50 have been further displaced. Here, the positional state 54 of the dose tracker 50 coincides and corresponds to the maximum dose positional state 55. Accordingly the indicator assembly 90 provides a first marker 85, e.g. in form of a second indication 92 that represents a confirmation that the dose tracker 50 has reached the maximum dose positional state 55.

[0178] The illustration of FIG. 4 is somewhat comparable to the configuration of FIG. 2. The configuration as illustrated in FIG. 5 is somewhat comparable to the configuration of FIG. 3. In FIG. 4 the preselector 70 has been moved to a second preselection positional state 110. In comparison to FIG. 2 the second preselection positional state 110 represents a larger maximum dose of the medicament to be expelled. Also here, the reduced length of the arrow representing the actual positional state 54 of the dose tracker 50 illustrates that the dose tracker 50 has not yet reached the maximum dose positional state 55. Accordingly, the indicator assembly 90 provides a first indicator 191 that differs from a second indicator 192 as illustrated in FIG. 5. Also here, the second indicator 192 represents a first marker 85 that is indicative that the dose tracker 50 has reached the maximum dose positional state 55. The indicators 90, 91, 191, 192 may comprise symbols, numbers, letters or just a differently colored structure in order to distinguish between the maximum dose positional state of the dose tracker and a non-maximum dose positional state of the dose tracker.

[0179] With the present injection device 1 injection and hence dispensing of the dose should only be triggered and commence when the dose tracker has reached the maximum dose positional state 55.

[0180] The preselector 70 is at least one of translationally or rotationally displaceable relative to the housing 10 between the at least two preselection positional states 110, 110. In any of the available preselection positional states 110, 110 the preselector is lockable relative to the housing 10. Hence during dose setting the preselector 70 is stationary or fixed to the housing 10 while the dose tracker 50 is subject to at least one of a translational or rotational displacement relative to the housing 10.

[0181] The schematic illustration of the injection device 1 directly corresponds to the implementation of an injection device as described later with regard to FIGS. 9-19. Here, the indicator assembly 90 is integrated or connected to the preselector 70. The dose tracker is provided with at least a first marker 85. The indicator assembly 90 is configured to reveal the first marker 85 on the dose tracker 50 when the dose tracker 50 reaches the maximum dose positional state 55. In the maximum dose positional state 55 the relative position or orientation of the first marker coincides or aligns with the position of the indicator assembly 90. In this way and when reaching the maximum dose positional state 55 the at least first marker 85 is revealed by the indicator assembly 90. For instance, the indicator assembly 90 may comprise an aperture 75 through which aperture the dose tracker or at least a portion thereof, namely a portion provided with the first marker 85 is discernible.

[0182] In the schematic representation of FIG. 6 the indicator assembly 190 is implemented as an electronic indicator assembly. The indicator assembly 190 may interact separately with the dose tracker 150 and with the preselector 170. For instance, the indicator assembly 190 may be configured to determine the preselection positional state 110 of the preselector 170 separate from the positional state 54 of the dose tracker 150. Here, the indicator assembly 190 does not have to be integrated or connected to the preselector 170. The indicator assembly 190 may be located elsewhere in or on the housing 10 of the injection device 1.

[0183] Typically, the indicator assembly 190 comprises a first position sensor 430 configured to determine or to detect a positional state of the dose tracker 150. The indicator assembly 190 may comprise a second position sensor 390 configured to determine or to detect a positional state of the preselector 170. Moreover, the electronically implemented indicator assembly 190 may comprise a processor 420 to process signals obtainable from the first position sensor 390 and obtainable from the second position sensor 430.

[0184] The processor 420 may be configured to compare the positional state of the dose tracker 150. If the processor 420 determines that the positional state of the dose tracker 150 corresponds to the maximum dose positional state 55 as governed and defined by the momentary preselection positional state 110 of the preselector 70 the processor 420 is configured go provide a respective indicator on an electronic display 410 of the indicator assembly 190. The indicator assembly 190 may further comprise a communication unit 440, e.g. implemented in form of an antenna to receive and/or to transmit electronic data or signals. By means of the communication unit 440 the indicator assembly 190 may exchange data with an external electronic device 500.

[0185] The external electronic device 500 may be implemented as a smartphone. The external electronic device may comprise a portable electronic device. It may be provided with a software or a software application that is configured to communicate with the communication unit 440 in a wireless way.

[0186] The drive mechanism 8 and the dose setting mechanism 9 as well as the preselector 170 and the dose tracker 150 do not have to be implemented all mechanically. At least one of the drive mechanism 8, the dose setting mechanism 9, the dose tracker 150 and the preselector 170 may be implemented electromechanically. In this way the indicator assembly 190 or its processor 420 can be configured to reconfigure the preselector 170. For instance, the external electronic device 500 may be configured to communicate with the processor 420 via the communication unit 440 to modify the configuration of the preselector 170. When implemented as an electromechanical dose setting mechanism 9 the preselector 170 may be electronically implemented and may be reconfigurable remotely by means of at least one of the electronic device 500 and the processor 420.

[0187] In FIG. 7 another embodiment of the injection device 1 is illustrated. Here, the indicator assembly 190 is not integrated into the device 1 but is provided as a remote indicator assembly 490 that is provided in or on an add-on device 400. The add-on device 400 is configured for detachable attachment to the housing 10 of the injection device 1. The add-on device 400 comprises all those features and components of the electronic indicator assembly 190 as described above in connection with FIG. 6. The detachable add-on device 400 is particularly configured and dedicated for use with injection devices 1 that are configured as disposable injection devices and which are intended to be discarded entirely once the medicament has been used up.

[0188] In FIG. 8 a rather schematic illustration of the add-on device 400 is provided. The add-on device 400 comprises the remote indicator assembly 490 that is configured to visualize or to indicate audibly or haptically to a user that a maximum dose positional state 55 of the dose tracker 150 has been reached. The electronic display 410 may comprise a so called electronic paper or e-paper display device that mimics the appearance of ordinary ink on paper. The electronic display 410 may comprise one of an electrophoretic display, a micro encapsulated electrophoretic display, an electrowetting display, an electrofluidic display and a plasmonic electronic display. Such electronic paper displays only consume a minimum of electric energy.

[0189] The communication unit 440 may comprise an antenna, such as an RFID antenna. The external electronic device 500 may comprise an RFID reader configured to wirelessly provide and to wirelessly transfer electric energy to the remote indicator assembly 490. Alternative or additional the communication unit 440 may comprise other radio frequency based antennas that may be configured to support one of a WLAN, Wi-Fi or Bluetooth communication protocol. In this way the processor 420 and the electronic display 410 may receive sufficient power for visualizing or for generally indicating the positional state of the dose tracker 150 relative to the preselector 170. The add-on device 400 and/or the remote indicator assembly 490 may also comprise at least one actuation element 450, in form of at least one or several buttons. The actuation element 450 may be also integrated into the electronic display 410. Here, the electronic display 410 may comprise a touch sensitive display.

[0190] By means of the actuation element 450 a user may confirm that a dose dispensing operation has just been conducted. Also during dispensing or during dose setting the user may press on the actuation element 450 thus inducing a change of the visual appearance of the electronic display 410. In this way, the electronic display 410 may alternately provide information regarding the preselection positional state and a momentary positional state of the dose tracker.

[0191] In the following an example of a handheld and all mechanically implemented injection device 1 is described with regard to FIGS. 9 and 10.

[0192] The injection device 1 as shown in FIGS. 9 and 10 is a pre-filled disposable injection device that comprises a housing 10 to which an injection needle 15 can be affixed. The injection needle 15 is protected by an inner needle cap 16 and either an outer needle cap 17 or a protective cap 18 that is configured to enclose and to protect a distal section of the housing 10 of the injection device 1. The housing 10 may comprise and form a main housing part configured to accommodate a drive mechanism 8 as shown in FIG. 10. The injection device 1 may further comprise a distal housing component denoted as cartridge holder 14. The cartridge holder 14 may be permanently or releasably connected to the main housing 10. The cartridge holder 14 is typically configured to accommodate a cartridge 6 that is filled with a liquid medicament. The cartridge 6 comprises a cylindrically-shaped or tubular-shaped barrel 25 sealed in proximal direction 3 by means of a bung 7 located inside the barrel 25. The bung 7 is displaceable relative to the barrel 25 of the cartridge 6 in a distal direction 2 by means of a piston rod 20. A distal end of the cartridge 6 is sealed by a pierceable seal 26 configured as a septum and being pierceable by a proximally directed tipped end of the injection needle 15. The cartridge holder 14 comprises a threaded socket 28 at its distal end to threadedly engage with a correspondingly threaded portion of the injection needle 15. By attaching the injection needle 15 to the distal end of the cartridge holder 14 the seal 26 of the cartridge 6 is penetrated thereby establishing a fluid transferring access to the interior of the cartridge 6.

[0193] When the injection device 1 is configured to administer e.g. human insulin, the dosage set by a dial 12 at a proximal end of the injection device 1 may be displayed in so-called international units (IU, wherein 1 IU is the biological equivalent of about 45.5 g of pure crystalline insulin (1/22 mg).

[0194] As shown further in FIGS. 9 and 10, the housing 10 comprises a dosage window 13 that may be in the form of an aperture in the housing 10. The dosage window 13 permits a user to view a limited portion of a number sleeve 80 that is configured to move when the dial 12 is turned, to provide a visual indication of a currently set dose. The dial 12 is rotated on a helical path with respect to the housing 10 when turned during setting and/or dispensing or expelling of a dose.

[0195] The injection device 1 may be configured so that turning the dosage knob 12 causes a mechanical click sound to provide acoustical feedback to a user. The number sleeve 80 mechanically interacts with a piston in the insulin cartridge 6. When the needle 15 is stuck into a skin portion of a patient, and when the trigger 11 or injection button is pushed, the insulin dose displayed in display window 13 will be ejected from injection device 1. When the needle 15 of the injection device 1 remains for a certain time in the skin portion after the trigger 11 is pushed, a high percentage of the dose is actually injected into the patient's body. Ejection of an insulin dose may also cause a mechanical click sound, which is however different from the sounds produced when using the dial 12.

[0196] In this embodiment, during delivery of the insulin dose, the dial 12 is turned to its initial position in an axial movement, that is to say without rotation, while the number sleeve 80 is rotated to return to its initial position, e.g. to display a dose of zero units.

[0197] The injection device 1 may be used for several injection processes until either the cartridge 6 is empty or the expiration date of the medicament in the injection device 1 (e.g. 28 days after the first use) is reached.

[0198] Furthermore, before using injection device 1 for the first time, it may be necessary to perform a so-called prime shot to remove air from the cartridge 6 and the needle 15, for instance by selecting two units of the medicament and pressing trigger 11 while holding the injection device 1 with the needle 15 upwards. For simplicity of presentation, in the following, it will be assumed that the ejected amounts substantially correspond to the injected doses, so that, for instance the amount of medicament ejected from the injection device 1 is equal to the dose received by the user.

[0199] The expelling or drive mechanism 8 as illustrated in more detail in FIG. 10 comprises numerous mechanically interacting components. A flange like support of the housing 10 comprises a threaded axial through opening threadedly engaged with a first thread or distal thread 22 of the piston rod 20. The distal end of the piston rod 20 comprises a bearing 21 on which a pressure foot 23 is free to rotate with the longitudinal axis of the piston rod 20 as an axis of rotation. The pressure foot 23 is configured to axially abut against a proximally facing thrust receiving face of the bung 7 of the cartridge 6. During a dispensing action the piston rod 20 rotates relative to the housing 10 thereby experiencing a distally directed advancing motion relative to the housing 10 30 and hence relative to the barrel 25 of the cartridge 6. As a consequence, the bung 7 of the cartridge 6 is displaced in distal direction 2 by a well-defined distance due to the threaded engagement of the piston rod 20 with the housing 10.

[0200] The piston rod 20 is further provided with a second thread 24 at its proximal end. The distal thread 22 and the proximal thread 24 are oppositely handed.

[0201] There is further provided a drive sleeve 30 having a hollow interior to receive the piston rod 20. The drive sleeve 30 comprises an inner thread threadedly engaged with the proximal thread 24 of the piston rod 20. Moreover, the drive sleeve 30 comprises an outer threaded section 31 at its distal end. The threaded section 31 is axially confined between a distal flange portion 32 and another flange portion 33 located at a predefined axial distance from the distal flange portion 32. Between the two flange portions 32, 33 there is provided a last dose limiter 35 in form of a semi-circular nut having an internal thread mating the threaded section 31 of the drive sleeve 30.

[0202] The last dose limiter 35 further comprises a radial recess or protrusion at its outer circumference to engage with a complementary-shaped recess or protrusion at an inside of the sidewall of the housing 10. In this way the last dose limiter 35 is splined to the housing 10. A rotation of the drive sleeve 30 in a dose incrementing direction 4 or clockwise direction during consecutive dose setting procedures leads to an accumulative axial displacement of the last dose limiter 35 relative to the drive sleeve 30. There is further provided an annular spring 40 that is in axial abutment with a proximally facing surface of the flange portion 33. Moreover, there is provided a tubular-shaped clutch 60. At a first end the clutch 60 is provided with a series of circumferentially directed saw teeth. Towards a second opposite end of the clutch 60 there is located a radially inwardly directed flange.

[0203] Furthermore, there is provided a dose dial sleeve also denoted as number sleeve 80. The number sleeve 80 is provided outside of the spring 40 and the clutch 60 and is located radially inward of the housing 10. A helical groove 81 is provided about an outer surface of the number sleeve 80. The housing 10 is provided with the dosage window 13 through which a part of the outer surface of the number 80 can be seen. The housing 10 is further provided with a helical rib at an inside sidewall portion of an insert piece 62, which helical rib is to be seated in the helical groove 81 of the number sleeve 80. The tubular shaped insert piece 62 is inserted into the proximal end of the housing 10. It is rotationally and axially fixed to the housing 10. There are provided first and second stops on the housing 10 to limit a dose setting procedure during which the number sleeve 80 is rotated in a helical motion relative to the housing 10. As will be explained below in greater detail, at least one of the stops is provided by a preselector stop feature 73 provided on a preselector 70.

[0204] The dose dial 12 in form of a dose dial grip is disposed about an outer surface of the proximal end of the number sleeve 80. An outer diameter of the dose dial 12 typically corresponds to and matches with the outer diameter of the housing 10. The dose dial 12 is secured to the number 80 to prevent relative movement therebetween. The dose dial 12 is provided with a central opening.

[0205] The trigger 11, also denoted as dose button is substantially T-shaped. It is provided at a proximal end of the injection device 10. A stem 64 of the trigger 11 extends through the opening in the dose dial 12, through an inner diameter of extensions of the drive sleeve 30 and into a receiving recess at the proximal end of the piston rod 20. The stem 64 is retained for limited axial movement in the drive sleeve 30 and against rotation with respect thereto. A head of the trigger 11 is generally circular. The trigger side wall or skirt extends from a periphery of the head and is further adapted to be seated in a proximally accessible annular recess of the dose dial 12.

[0206] To dial a dose a user rotates the dose dial 12. With the spring 40 also acting as a clicker and the clutch 60 engaged, the drive sleeve 30 the spring or clicker 40, the clutch 60 and the number sleeve 80 rotate with the dose dial 12. Audible and tactile feedback of the dose being dialed is provided by the spring 40 and by the clutch 60. Torque is transmitted through saw teeth between the spring 40 and the clutch 60. The helical groove 81 on the number sleeve 80 and a helical groove in the drive sleeve 30 have the same lead. This allows the number sleeve 80 to extend from the housing 10 and the drive sleeve 30 to climb the piston rod 20 at the same rate. At a limit of travel a radial stop on the number sleeve 80 engages either with a first stop or a second stop provided on the housing 10 provided on the pre-selector 70 to prevent further movement in a dose incrementing direction 4. Rotation of the piston rod 20 is prevented due to the opposing directions of the overall and driven threads on the piston rod 20.

[0207] The last dose limiter 35 keyed to the housing 10 is advanced along the threaded section 31 by the rotation of the drive sleeve 30. When a final dose dispensed position is reached, a radial stop formed on a surface of the last dose limiter 35 abuts a radial stop on the flange portion 33 of the drive sleeve 30, preventing both, the last dose limiter 35 and the drive sleeve 30 from rotating further.

[0208] Should a user inadvertently dial beyond the desired dosage, the injection device 1, configured as a pen-injector allows the dosage to be dialed down without dispense of the medicament from the cartridge 6. For this the dose dial 12 is simply counter-rotated. This causes the system to act in reverse. A flexible arm of the spring or clicker 40 then acts as a ratchet preventing the spring 40 from rotating. The torque transmitted through the clutch 60 causes the saw teeth to ride over one another to create the clicks corresponding to dialed dose reduction. Typically, the saw teeth are so disposed that a circumferential extent of each saw tooth corresponds to a unit dose.

[0209] When the desired dose has been dialed the user may simply dispense the set dose by depressing the trigger 11. This displaces the clutch 60 axially with respect to the number sleeve 80 causing dog teeth thereof to disengage. However, the clutch 60 remains keyed in rotation to the drive sleeve 30. The number sleeve 80 and the dose dial 12 are now free to rotate in accordance with the helical groove 81.

[0210] The axial movement deforms the flexible arm of the spring 40 to ensure the saw teeth cannot be overhauled during dispense. This prevents the drive sleeve 30 from rotating with respect to the housing 10 though it is still free to move axially with respect thereto. The deformation is subsequently used to urge the spring 40 and the clutch 60 back along the drive sleeve 30 to restore the connection between the clutch 60 and the number sleeve 80 when the distally directed dispensing pressure is removed from the trigger 11.

[0211] The longitudinal axial movement of the drive sleeve 30 causes the piston rod 20 to rotate through the through opening of the support of the housing 10, thereby to advance the bung 7 in the cartridge 6. Once the dialed dose has been dispensed, the number sleeve 80 is prevented from further rotation by contact of at least one stop extending from the dose dial 12 with at least one corresponding stop of the housing 10. A zero dose position may be determined by the abutment of one of axially extending edges or stops of the number sleeve 80 with at least one or several corresponding stops of the housing 10.

[0212] The expelling mechanism or drive mechanism 8 as described above is only exemplary for one of a plurality of differently configured drive mechanisms that are generally implementable in a disposable pen-injector. The drive mechanism as described above is explained in more detail e.g. in WO2004/078239A1, WO 2004/078240A1 or WO 2004/078241A1 the entirety of which being incorporated herein by reference.

[0213] The injection device 1 further comprises a preselector 70 that is configured to define a maximum dose positional state 55 of the number sleeve 80. Here, the number sleeve 80 represents or substitutes the dose tracker 50 as described above. Although and in view of the indicator assembly 90 the number sleeve is no longer required to illustrate dose indicating numbers in the dosage window 13 of the housing 10. The dose tracker 50 and hence the number sleeve 80 comprises a tracking stop feature 51 to engage with a correspondingly shaped preselector stop feature 73 as will be described in greater detail with regard to FIG. 13.

[0214] As shown in FIGS. 11-13 the dose setting mechanism 9 comprises a preselector 70 that is at least one of translationally or rotationally displaceable relative to the housing 10 and hence relative to the sidewall 48 of the housing 10 between at least two preselection positional states 110, 110 and 110 as illustrated in the sequence of FIGS. 16, 17 and 18. The preselector 70 behaves as a limiter and provides a limiter function in order to delimit a displacement of the dose tracker 50 relative to the housing 10. The preselector 70 comprises a sleeve portion 71 enclosing at least a longitudinal section of the dose tracker 50 and hence of the number sleeve 80. Near an axial end the sleeve portion 71 comprises a preselector stop feature 73 in the form of an axial protrusion with a side edge extending parallel to the longitudinal axis of the housing 10.

[0215] The dose tracker 50 comprises a correspondingly shaped tracking stop feature 51. As shown in FIG. 13 there is a predefined axial distance between the tracking stop feature 51 and the preselector stop feature 73. The preselector 70 is hindered from rotation relative to the housing 10. It comprises a spline feature 74, which is in the form of a longitudinal protrusion received in a correspondingly shaped recess on an inside facing section of the sidewall 48 of the housing 10. In this way the preselector 70 is permanently rotationally locked to the housing 10. With the spline feature 74 the preselector 70 and its sleeve portion 71 is free to slide in axial or longitudinal direction relative to the housing 10. For providing a keyed engagement between the sleeve portion 71 and the housing 10 also the housing 10 may comprise a radially inwardly extending protrusion to slide in a groove or slot on the outside surface of the sleeve portion 71.

[0216] The preselector 70 further comprises a slider 72 that is accessible from outside the housing 10. The slider 72 can be integrally formed with the sleeve portion 71. The sleeve portion 71 and the slider 72 may be also provided as separate pieces that are connected together by mutually corresponding connectors, not explicitly illustrated here. The slider 72 is axially guided along a displacement path 49 formed by a recess 41 on an outside facing surface portion of the sidewall 48 of the housing 10. The recess 41 may be circumferentially confined by a surrounding edge 44 forming a stepped down portion in the outside surface of the sidewall 48. The recess 41 comprises a through opening 42 as indicated in FIG. 13. The through opening 42 is formed in a bottom section 43 of the recess. The through opening 42 comprises a longitudinal slit through which the interconnection of the sleeve portion 71 and the slider 72 extends. On the outside surface the slider 72 has a gripping structure 77 featuring various protrusions that are separated in axial direction so as to provide a rather slip-free engagement, e.g. with a finger of a hand of a user.

[0217] The preselector 70 further comprises a detent structure 76 best shown in FIG. 15. The detent structure 76 is configured to engage with a correspondingly shaped counter detent structure 46 provided on the sidewall 48 of the housing 10. The counter detent structure 46 comprises at least two recesses 47 that are separated from each other along the longitudinal axis. The detent structure 76 of the preselector 70 comprises a resiliently deformable snap feature, such as a radially deformable tongue to mechanically engage with one of the recesses 47 of the counter detent structure 46 of the housing 10. In this way the preselector 70 is displaceable relative to the housing between at least two preselection positional states 110, 110, 110. In any of the preselection positional states 110, 110, 110 the preselector 70 is locked to the housing. In order to displace the preselector 70 relative to the housing, e.g. from one preselection positional state 110 to another preselection positional state 110 the holding force acting between and provided by the detent structure 76 and the counter detent structure 46 must be overcome.

[0218] The axial position of the preselector 70 determines a maximum distance the dose tracker 50 can be displaced starting from a zero dose configuration as shown in FIG. 13, 16, 17 or 18 to a maximum dose configuration in which the dose tracker 50 protrudes from a proximal end of the housing 10 until the tracking stop feature 51 abuts with the preselector stop feature 73 thus blocking any further proximally directed and dose increasing rotation of the dose tracker 50 in unison with the dose dial 12.

[0219] The dose tracker 50 and hence the number sleeve 80 comprises a helical groove 81 engaged with a correspondingly shaped protrusion 63 provided at the proximal end of the housing 10. The protrusion 63 may be provided on an inside facing surface portion of the insert 62 fixed to the proximal end of the housing 10. The insert facilitates assembly of the components inside the housing of the injection device.

[0220] Also a portion of the bottom section 43 and hence of the recess 41 may be provided by the insert 62. The insert 62 may provide a proximal end cap of the housing 10 of the injection device 1.

[0221] The preselector 70 is arrestable or fixable to the sidewall 48 of the housing 10 in at least two different discrete positions denoted as preselection positional states 110, 110, 110. The axial distance between neighboring preselection positional states 110, 110 is identical and corresponds to the longitudinal advancing motion of the dose tracker 50 as the dose tracker 50 undergoes a complete revolution relative to the housing 10. In this way it is guaranteed, that the tracking stop feature 51 always exactly engages with the preselector stop feature 73 when reaching the maximum dose positional state 55.

[0222] In the configuration as shown in FIG. 16 the dose tracker 50 can be rotated at least by one complete revolution until its tracking stop feature 51 abuts and engages with the preselector stop feature 73. By displacing the preselector 70 to the next preselection positional state 110 as shown in FIG. 17, the dose tracker 50 can be rotated at least by two complete revolutions until the tracking stop feature 51 and the preselector stop feature 73 mechanically engage thereby blocking any further dose increasing displacement of the dose tracker 50 and hence of the dose dial 12.

[0223] In the configuration of FIG. 18 the preselector 70 is in the most proximal position of three discrete allowable and supported preselection positional states 110, 110, 110. In this position of the preselector 70 the dose tracker 50 can be rotated at least by three complete revolutions relative to the housing 10.

[0224] In FIG. 19 an isolated view of the dose tracker 50 in form of the number sleeve 80 is provided. As shown there the outside surface of the dose tracker 50 comprises a first marker 85. The first marker 85 comprises a first surface section 82 that may be provided with a first indication 91. The marker 85 comprises a second surface section 84 non-overlapping with the first surface section 82. The second surface section 84 may be provided with a second indication 92. As already described in connection with FIGS. 2 and 3 first and second indications 91, 92 may comprise different symbols or different colors.

[0225] The second surface section 84 and hence the second indication 92 may provide a confirmation symbol indicating to the end user that the dose tracker 50 has reached the predefined maximum dose positional state 55. The second surface section 84 and the second indication 92 are arranged in such a distance to the tracking stop feature 51 which distance substantially corresponds to the longitudinal distance between the preselector stop feature 73 and an aperture 75 provided in the preselector 70. The aperture 75 extends radially through the preselector 70. The aperture 75 may extend through an overlapping portion of the sleeve portion 71 and the slider 72. As illustrated in FIG. 16 the aperture 75 may be provided with a magnifying lens 78.

[0226] In this way and when reaching the maximum dose positional state 55 in which the tracking stop feature 51 engages with the preselector stop feature 73 the second surface portion 84 and hence the second indication 92 overlaps with and aligns with the aperture 75 so that the second surface portion 84 and the second indication 92 provided thereon becomes discernible and visible through the aperture 75. This is an indication to the end user that the maximum dose positional state 55 has been reached.

[0227] Before reaching the maximum dose positional state 55 the first surface portion 82, eventually with the first indication 91 is revealed in the aperture 75 thus indicating to the user that the maximum dose positional state 55 has not yet been reached and that dispensing should not yet commence.

[0228] On an outside surface of the sidewall 48 of the housing 10 there is further provided at least one preselection indication 45. Apparently and as illustrated in FIGS. 11 and 12 there are provided three consecutive preselection indications 45. The preselection indications 45 comprise a triangular shaped pointer in combination with a number, e.g. 1, 2, 3. The preselection indications 45 are arranged along the displacement path 49 of the preselector 70 and hence of its slider 72. Near or aligned with the aperture 75 there is further provided a pointer 79. Since the preselection indications 45 are separated along the displacement path 49 of the preselector 70 in any one of the preselection positional states 110, 110, 110 the pointer 79 points to one of the preselection indications 45. The preselection indication 45 in the present embodiment corresponds to the total number of revolutions of the dose tracker 50 for the respective preselection positional state. However, the preselection indication 45 may also represent standard units of the medicament to be dispensed or may provide any other dose size indicating symbol.

[0229] In the sketches of FIGS. 11 and 12 the preselector 70 is in the largest preselection positional state 110. Accordingly, the pointer 79 is in alignment with the largest preselection indication 45, namely with number 3.

[0230] The position of the preselector 70 relative to the housing 10 is therefore indicative of the maximum dose that can be set with the dose setting mechanism 9. The indicator assembly 90 presently integrated into the preselector 70 is then indicative, that the momentary configuration and status of the dose setting mechanism 9 corresponds to the pre-set dose.

[0231] Even though the presently illustrated embodiments only show a fixing or locking of the limiter 70 or the preselector 70 at discrete positions relative to the housing 10 that correspond to consecutive and complete revolutions of the dose tracker 50 it is also conceivable that the dose tracker 50 comprises two or even three tracking stop features 51 to engage with the limiter stop feature or preselector stop feature 73. Alternatively also the preselector 70 may comprise two or more preselector stop feature 73 to engage with the tracking stop feature 51. In this way the maximum dose positional state could be assigned with every half or every third revolution of the dose tracker 50 relative to the housing 10. Furthermore it is conceivable, that two or more tracking stop feature 51 simultaneously engage with correspondingly shaped two or more preselector stop feature 73. In this way the mechanical interaction and robustness of the abutment between the dose tracker 50 and the preselector 70 can be enhanced and increased.

[0232] FIGS. 20-24 show another example of an injection device. Here and contrary to the injection device 1 as described in connection with FIGS. 11-19 the indicator assembly 190 is implemented as an electronic indicator assembly. As shown in FIG. 20 the electronic indicator assembly 190 comprises an electronic display 410 having a first display section 412 and having a second display section 414. The display 410 is typically provided on or near a proximal end of the housing 10. The preselector 170 is all mechanically implemented as already described in connection with FIGS. 11-19. Also here the preselector 170 comprises a sleeve portion 171 that is rotationally locked to the housing 10 by means of a spline feature 174 on an outside surface of the sleeve portion 171.

[0233] The sleeve portion 171 encloses a portion of an outside surface of the dose tracker 150. Also here the dose tracker 150 comprises a number sleeve 180. The dose tracker 150 also comprises a tracking stop feature 151 to abut and to engage with a correspondingly shaped preselector limiting stop feature 173. The sleeve portion 171 is connected to a slider 172 having a gripping structure 177 on an outside facing surface section. The slider also comprises a pointer 179 to point to one of the three preselection indications 45 that are arranged along the displacement path 49 of the slider 172. Even though not illustrated in detail the preselector 70 and the housing 10 comprise a detent structure 76 and a counter detent structure 46 as described in connection with FIGS. 14 and 15 above.

[0234] In this way the preselector 170 can be fixed and locked to the sidewall 48 of the housing 10 in any of the available preselection positional states 110, 110, 110.

[0235] Contrary to the example as shown in FIGS. 11-19 the indicator assembly 190 is provided separate from the preselector 170. For this the indicator assembly 190 comprises a first position sensor 430 and a second position sensor 390 as illustrated in FIG. 27. The first position sensor 430 is configured to determine or to detect a positional state of the dose tracker 150 relative to the housing 10. The second position sensor 390 is configured to determine and to detect a preselection positional state of the preselector 70. Both position sensors 430, 390 are configured to generate electric signals being indicative of the detected position of the dose tracker 150 and the preselector 170.

[0236] The indicator assembly 190 further comprises a processor 420 connected to the first position sensor 430 and connected to the second position sensor 390. In this way the indicator assembly 190 is enabled to compare a measured or detected positional state 54 of the dose tracker 150 with the preselection positional state 110 of the preselector 170. Depending on the comparison the electronically implemented indicator assembly 190 is configured to provide one of at least two indicators 191, 192 as shown in FIGS. 20 and 21. In FIG. 20 in which the dose tracker is not yet in the maximum dose positional state 55 the indicator assembly 190 provides a first indication 191 in the second display section 414 thus illustrating to the user that the dose dial 12 has to be rotated further.

[0237] If the dose dial 12 has been rotated further so that the dose tracker 50 is screwed out of the housing 10 in proximal direction the tracking stop feature 151 engages with the preselector stop feature 173. The position of the dose tracker 150 detected by the indicator assembly 190 then reveals that the maximum dose positional state 55 has been reached. Accordingly, the indicator assembly 190 is configured to provide the second indication 192 in the second display section 414 of the display 410 thereby confirming to the user that the dose tracker 150 has reached the intended maximum dose positional state 55. In the configuration as shown in FIG. 21 the injection device 1 is ready for starting a dispensing operation.

[0238] In the first display section 412 there is provided the preselection indication 45 to which the pointer 179 of the slider 172 actually points. In the configuration of FIGS. 20 and 21 the pointer 179 is in alignment with the smallest preselection indication 445 of three available preselection indications 45. In the configuration of FIGS. 22 and 23 the preselector 170 has been displaced to a different preselection positional state 110 compared to the preselection positional state 110 as shown in FIG. 20. Correspondingly, in the first display section 412 the preselection indication 45 coinciding with the pointer 179 is reproduced. In a zero dose configuration in which the dose dial 12 and hence the dose tracker 150 have not yet been dialed or displaced in a dose incrementing direction the second display section 414 provides the first indication 191 as described above thereby indicating that the maximum dose positional state has not yet been reached.

[0239] By rotating and displacing the dose tracker 50 relative to the housing 10 along the dose incrementing direction 4 until the maximum dose positional state 55 has been reached, as shown in FIG. 23, the electronic display 410 of the indicator assembly 190 switches to the second indication 192 thereby confirming that the maximum dose positional state 55 has been reached. The device is then ready to commence and to conduct a dose dispensing procedure.

[0240] The preselector 170 comprises an extension 176. In the present illustration the extension 176 is radially overlapping at least with a portion of the electronic indicator assembly 190. The extension 176 is provided with a second marker 175. The second marker 175 is configured to interact with the sensor sections 391, 392, 393 of the second position sensor 390 as shown in FIG. 27. The second marker 175 is provided on an outside facing surface of the preselector 170. In any of the available preselection positional states 110, 110, 110 the second marker 175 is in contact or is aligned with only one of the sensor sections 391, 392, 393. In the preselection positional state 110 representing the smallest maximum dose size the second marker 175 may be aligned with the sensor section 393.

[0241] In an intermediate preselection positional state 110 the second marker 175 is aligned with the sensor section 392. In the preselection positional state 110 representing a maximum dose the second marker 175 is aligned with the sensor section 391. The second marker 175 may be electrically conducting. Its presence or vicinity to any one of the sensor sections 391, 392, 393 can be electronically detected by means of the processor 420 of the indicator assembly 190 being electrically connected to the position sensor 390.

[0242] In a similar way the first position sensor 430 may comprise a first detector element 422 and a second detector element 424. The detector elements 422 424 are arranged axially offset. They may be implemented as electrical contacts or as electromechanical switches, which upon mechanical contact with another structure or component may generate or interrupt an electrical signal that is transferrable to the processor 420. On an outside surface of the number sleeve 180 and hence on an outside surface of the dose tracker 150 there are provided two surface sections, namely a first surface section 182 and a second surface section 184. The surface sections 182, 184 comprise the shape of a helical thread.

[0243] The lead of the helical threads of the first and second surface sections 182, 184 is identical to a lead of a helical groove 181 of the dose tracker 150 or the number sleeve 180. As the dose tracker 150 is subject to a helical motion relative to the sidewall 48 of the housing 10 the first detector element 422 slides along the first surface section 182. Likewise, the second detector element 424 slides along the second surface section 184.

[0244] In the zero dose configuration as shown in FIG. 29 both detector elements 422, 424 are in contact with the respective first and second surface sections 182, 184. The outside surface of the number sleeve 180 and hence of the dose tracker 150 comprises at least a first marker 185 by way of which the first position sensor 430 becomes enabled to determine and to detect at least one of an axial or rotational position of the dose tracker 150. The marker 185 comprises at least two interrupts 183, 186 in the first surface section 182 and in the second surface section 184, respectively. In the illustration of FIGS. 29-33 the distal direction points to the right whereas the proximal direction points to the left.

[0245] As illustrated in FIG. 31 the first surface section 182 comprises a first interrupt 183. As illustrated in FIG. 30 the second surface section 184 comprises a second interrupt 186. After a complete revolution of the dose tracker 150 and hence of the number sleeve 180 the second interrupt 186 is aligned with the second detector element 424 as illustrated in FIG. 30. In this way, the second detector element 424 is switched. The second detector element 424 when aligned with the interrupt 186 may generate or interrupt an electrical signal that differs from an electrical signal of the second detector element 424 when aligned with the second surface section 184.

[0246] After two revolutions the opposite situation occurs as illustrated in FIG. 31. There, the second detector element 424 is in alignment and is in contact with the second surface section 184 while the first detector element 422 is in alignment with the first interrupt 183 of the first surface section 182. This configuration may represent a logical 2 while the configuration of FIG. 30 may represent a logical 1. In FIG. 32 and after three complete revolutions of the dose tracker 150, none of the detector elements 422, 424 remains in contact with any of the first or second surface sections 182, 184. This configuration may represent a logical 3. Hence, with two detector elements 424, 424 and with two surface sections 182, 184 each of which comprising at least one interruption 183, 186 four different discrete states of the dose tracker 150 can be electronically detected and determined.

[0247] The detector elements 421, 422, 424 can be implemented as mechanical switches when the surface sections 382, 384 and the interrupts 183, 186 comprise different radial height or depth on the outside surface of the 150. For instance, the surface sections 382, 384 each comprise a longitudinal groove on the outside surface of the number sleeve 180. The interrupts 183, 186 may flush with the outside surface of the number sleeve 180 or of the dose tracker 150. When implemented as mechanical switches, the detector elements 422, 424 may each comprise a radially displaceable and spring biased pin running along the respective surface section 182, 184 as the number sleeve 180 is subject to a rotation relative to the housing 10. When a pin of one of the detector elements 422, 424 aligns with an interrupt 183, 186 the respective pin is depressed against the action of the spring. Such a depression is accompanied by a closing or opening of an electrical switch or contact inside the detector element 422, 424.

[0248] There is further illustrated an optional detector element 421 that serves as an on-off switch for the add-on device 400. The further detector element 421 is configured to engage with a further surface section 188 on the outside surface of the number sleeve 80. The surface section 188 as illustrated in FIGS. 29 and 30 comprises a confined recess in the outside surface of the number sleeve 180 or of the dose tracker 150. The recess and hence the surface section 188 is only slightly larger than the extent of the detector element 421. In an initial configuration or zero-dose configuration as for instance illustrated in FIG. 29 the detector element 421 is in alignment with the recess at the surface section 188.

[0249] As soon as the number sleeve 180 is subject to a rotation relative to the housing 10 the detector element 421 and the recess 188 get out of engagement. Consequently, the detector element 421 will be subject to a radially outwardly directed depression as it starts to slide outside the recessed surface section 188 and hence along the outside surface of the number sleeve 180. In this way the add-on device 400 and hence the electronic components thereof, in particular its processor 420, is switched on and the status of the further detector elements 422, 424 can be monitored and processed. By means of a detector element 421 implemented as on/off switch, electric energy consumption of the add-on device 400 can be reduced and battery lifetime can be prolonged.

[0250] When after completion of a dose dispensing procedure the detector element 421 re-engages the recessed surface section 188 the add-on device 400 is switched off and electric energy can be saved.

[0251] The first position sensor 430 and the second position sensor 390 can be implemented in many different ways. Here, the first and second surface sections 182, 184 may be provided as radial grooves while the interrupts 183, 186 protrude radially from the respective groove. Alternatively, the interrupts 183, 186 can be provided as non-conductive sections on respective first and second electrically conductive surface sections 182, 184; or vice versa. Alternatively, the first and/or second surface sections 182, 184 could be electrically or magnetically encoded. For instance, the surface sections 182, 184 may be electrically conductive while the interrupts 183, 186 are electrically insulating or non-conductive. It is also conceivable that the surface sections 182, 184 and the interrupts 183, 186 mutually distinguish in terms of their visual appearance or light absorption characteristic as well and/or with regards to their magnetic properties.

[0252] In this way also other encoding schemes based on an optic encoding or magnetic encoding can be generally implemented. With an optically or magnetically implemented encoding of the outside surface 85 of the dose tracker 150 or the number sleeve 180 also respective first and second detector elements 422, 424 should be implemented. Here, first and second detector elements 422, 424 may be implemented as light detectors or as magnetic sensors.

[0253] In a situation wherein the slider 172 is located near the proximal end of the displacement path and wherein a maximum dose has been pre-selected, i.e. with the pointer 179 of the slider 172 aligns with the preselection indication 45 provided with number 3 the configurations as shown in FIGS. 29, 30 and 31 correspond to positions of the dose tracker 150 and hence of the number sleeve 180 that are smaller than the pre-selected dose size. Only when arriving in the proximal end position, in which the preselector stop feature 173 engages with the tracking stop feature 151 the electronic position detection of the dose tracker 150 coincides with the electronic position detection of the preselector 170. In such a situation the processor 420 is configured to switch the indicator 415 in the second display section 414 to confirm that the intended dose size has been set.

[0254] These electronic components may belong to the injection device 1 and hence to the dose setting mechanism 9 thereof. The injection device 1 may be further equipped with one or several electric power sources 402, such as button batteries. The electric power sources 402 can be integrated into the housing 10 or can be detachably mounted inside the housing 10 and/or its sidewall 48.

[0255] In a further embodiment and as indicated in FIG. 26 the electronic components as well as the electric power sources 402 can be all integrated into an add-on device 400 that may be detachably connectable to the housing 10, in particular to its sidewall 48. A detachable add-on device 400 may be usable with disposable injection devices that are equipped with a pre-filled cartridge 6 and which are intended to be discarded entirely after the content of the cartridge 6 has been used up.

[0256] Here, the injection device 1 could be void of an own indicator assembly 190. The add-on device 400 can be provided with a remote indicator assembly 490 which has the same structure as the indicator assembly 190 as described above. Here, all components belonging to the indicator assembly 190 are provided on the detachable add-on device 400, which may have a fastener or fastening structure 404 to engage with a correspondingly shaped counter fastener 406 in order to guarantee a correct and well-defined position of the add-on device 400 relative to the housing 10, to the dose tracker 150 and to the preselector 170.

[0257] The add-on device 400 is further equipped with the above mentioned first and second position sensors 430, 390 configured to detect and to determine a position of the dose tracker 150 relative to the preselector 170.

TABLE-US-00001 List of reference numbers 1 injection device 2 distal direction 3 proximal direction 4 dose incrementing direction 5 dose decrementing direction 6 cartridge 7 bung 8 drive mechanism 9 dose setting mechanism 10 housing 11 trigger 12 dial 13 dosage window 14 cartridge holder 15 injection needle 16 inner needle cap 17 outer needle cap 18 protective cap 20 piston rod 21 bearing 22 first thread 23 pressure foot 24 second thread 25 barrel 26 seal 28 threaded socket 30 drive sleeve 31 threaded section 32 flange 33 flange 35 last dose limiter 36 shoulder 40 spring 41 recess 42 through opening 43 bottom section 44 edge 45 preselection indication 46 counter detent structure 47 recess 48 sidewall 49 displacement path 50 dose tracker 51 tracking stop feature 54 positional state 55 maximum dose positional state 60 clutch 62 insert 63 protrusion 64 stem 70 preselector 71 sleeve portion 72 slider 73 preselector stop feature 74 spline feature 75 aperture 76 detent structure 77 gripping structure 78 lens 79 pointer 80 number sleeve 81 groove 82 surface section 84 surface section 85 marker 90 indicator assembly 91 indication 92 indication 110 preselection positional state 150 dose tracker 151 tracking stop feature 170 preselector 171 sleeve portion 172 slider 173 preselector stop feature 174 spline feature 175 marker 176 extension 177 gripping structure 179 pointer 180 number sleeve 181 groove 182 surface section 183 interrupt 184 surface section 185 marker 186 interrupt 188 surface section 190 indicator assembly 191 indication 192 indication 390 position sensor 391 sensor section 392 sensor section 393 sensor section 400 add-on device 402 electric power source 404 fastener 406 counter fastener 410 electronic display 412 display section 414 display section 420 processor 421 detector element 422 detector element 424 detector element 430 position sensor 440 communication unit 450 actuation element 490 remote indicator assembly 500 external electronic device