Patent Application
20140312074
The present invention relates to medical injection devices adapted for injecting apportioned doses of a drug. More specifically, the invention relates to drive mechanisms for medical injection devices incorporating spring assisted dose delivery and methods for manufacture thereof.
In particular, the invention provides improvements with respect to manufacturability and assembling operations during manufacture of a spring assisted injection device.
In the disclosure of the present invention reference is mostly made to the treatment of diabetes by injection or infusion of insulin, however, this is only a preferred use of the present invention.
In order to permit a patient to administer a proper dose of a medicament, various mechanical injection devices have been proposed such as the devices shown in WO 01/95959. Such injection devices facilitate easy and safe dose setting as well as subsequent administration of the set dose by means of a manually operable injection button. Some devices, such as the devices shown in WO 2008/116766 A1, incorporate a spring member wherein energy is stored during a dose setting operation. Upon activation of an injection button, the expelling operation is performed by means of an injection mechanism that utilizes the energy stored in the spring member for expelling the set dose.
WO 2010/033778 A2 discloses a medical injector which includes a spring for urging and displacing a sleeve causing mixing of mixable components of a held reservoir. A releasable retainer retains the sleeve against the force of the spring. Prior to release of the releasable retainer, the releasable retainer cooperates with a channel formed in the body of the injector.
Manufacture of injection devices incorporating a spring assisted injection mechanism usually introduce complexities due to the requirement of assembling one or more springs in a pre-tensioned state. This issue is particularly relevant when manufacturing injection devices that offers user adjustable dose setting.
Having regard to the technical complexity issues of the above-identified prior art, it is an object of the invention to provide a spring assisted injection device that provides for manufacture in a simplified and cost-effective way.
In a first aspect the present invention relates to a drive mechanism for an injection device configured for setting and expelling set doses of a drug from a drug-filled cartridge, the drive mechanism comprising:
According to the above aspect, by tensioning the spring device and locking the axial movement of the counter-element by means of an interlock between the counter-element and the piston driver, the spring device is in a controlled state, easy to assemble with the remaining components of the device and enabling simple insertion into casing elements forming a housing of the injection device. After the drive mechanism subassembly formed by the piston driver, the counter-element and the spring device has been arranged relative to the housing of the device, the interlock state may be subsequently released allowing the counter-element and the piston driver to axially move relative to each other and enables the dose setting mechanism to be operated between the minimum dose setting state and the maximum dose setting state.
In some embodiments the piston driver comprises a piston driver thread that engages a thread of a further component of the injection device. In accordance with these threaded components, the piston driver rotates and moves in an axial direction as a dose is being dialed up or down.
Also, in some embodiments a piston rod couples movement of the piston driver with movements of the piston during expelling of a set dose. The piston rod and the piston driver may be coupled so as to enable telescopically lengthening of the assembly formed by the piston rod and the piston driver during dose setting.
In some forms the said telescopically lengthening of the piston rod and the piston driver is provided by means of the piston driver thread engaging a thread defined by the piston rod. In other forms the said telescopically lengthening of the piston rod and the piston driver is provided by means of ratchet mechanism, such as an axial ratchet mechanism. The ratchet mechanism may incorporate ratchet teeth providing a one-way lengthening of the assembly formed by the piston driver and the piston rod.
In injection devices where the drive mechanism subassembly is placed radially into the housing of the device, the above assembly may be easily introduced into the housing as the assembly in the interlocked state will fit more easily into the housing. In addition, the radial placement of the subassembly enables better integration with additional components, such as electronic circuitry including position sensors to monitor movements of selected components of the device.
The longitudinal track and the track follower may be formed to unambiguously define the relative rotational position between the piston driver and the counter-element when the piston driver and the counter-element by a relative axial movement is/are shifted between the minimum dose setting state and the maximum dose setting state.
In one form the interlock is so configured that a relative rotational movement between the piston driver and the counter-element is required for activating and/or releasing the interlock.
In further embodiments the interlock may be so configured that activation and/or release of the interlock requires the spring device to be tensioned further than at the maximum dose setting state.
Also, the interlock may be so configured that a force originating from the spring device acts to maintain the interlock in the interlocked state.
In certain embodiments, the longitudinal track is configured for rotationally locking the piston driver relative to the counter-element during relative axial movements from the minimum dose setting state to the maximum dose setting state and vice versa. Hence, the piston driver may be rotationally locked relative to the counter-element to follow rotation of a dose setting knob of the device during dose setting. During dose expelling, the piston driver may remain rotationally locked.
Alternatively, in other embodiments, the longitudinal track may be formed generally longitudinally extending along the axis but with a pitch relative to said axis so that the piston driver and the counter-element rotates relatively to each other when being shifted between the minimum dose setting state and the maximum dose setting state. A corresponding rotation may occur during dose expelling from the set dose to the end of dose position which corresponds to the minimum dose position.
As noted above the piston driver may be configured to move axially relative to the piston rod during dose setting. Also, the piston driver may be configured to move axially relative to the housing during dose expelling.
In some embodiments the piston rod remains stationary relatively to the housing during dose setting.
The track follower may in some embodiments form part of the interlock.
The longitudinal track may define a main direction generally running along said axis. An interlock track may connect with the longitudinal track so that the track follower is receivable in the interlock track. The interlock track may extend sideways, i.e. in a circumferential direction relative to the main direction, so that a relative rotational movement between the piston driver and the counter-element enables activation and/or release of the interlock. Hence during activation and/or release of the interlock the track follower moves along the interlock track.
In some embodiments the interlock track forms a ramp shaped angled surface for releasably maintaining the piston driver and the counter-element in the interlocked state.
In alternative embodiments the piston driver and the counter-element define interlock geometries separate from the track follower and/or the longitudinal track.
In some embodiments, the injection device is for setting and expelling set doses of a drug from a drug-filled cartridge of the kind comprising an outlet and a slideably arranged piston which is driveable in a distal direction to expel the drug through the outlet. The injection device may in some embodiments further comprise a) a housing, b) a piston rod adapted to cooperate with the piston of the cartridge to cause a set dose to be expelled, c) a piston driver coupled to the piston rod, the piston driver being rotated during dose setting away from an initial position to effect the adjustment of the effective length of the piston rod and the piston driver, d) a dosing member mounted rotatably movable but axially fixed in the housing, the dosing member being prevented from rotating during dose setting and allowed to rotate during dose delivery, the dosing member controlling the distal movement of the piston rod during dose injection.
The initial position may correspond to a so-called end of dose state, i.e. the condition that the piston driver assumes after a complete expelling of a previously set dose.
In the present context the term ‘injection device’ should be interpreted to mean a device which is suitable for injecting a drug, such as a liquid drug, into a human or animal body. The injection device is preferably of the kind being suitable for performing repetitive self injection of drug, e.g. insulin for persons having diabetes, or growth hormone. The injection device may be in the form of an injection pen, i.e. of a kind having an elongated shape similar to that of an ordinary pen. Such injection device generally is characterized in that the device part which is intended to rest against an injection site is only held against the skin of the patient during injection of the drug, such as for a duration of less than 1 minute for the complete expelling of a previously set dose.
As mentioned above, the drug is preferably a liquid drug suitable for injection into a human or animal body, e.g. subcutaneously or intravenously. Alternatively, the drug may be a dry drug which has to be reconstituted prior to injection.
The housing may in some embodiments be a part of the injection device which at least substantially encloses the remaining parts of the injection device. Thus, the housing defines an outer boundary of the injection device. The housing may be substantially closed, i.e. it may have substantially solid walls, or it may comprise more or less open parts, such as openings, grids, etc.
The dose setting mechanism is the part of the injection device which is used for setting a desired dose. It may advantageously comprise a part which can be manipulated by an operator and one or more parts which ensure(s) that when an operator manipulates the relevant part, then the injection device is set in such manner that when the injection mechanism is subsequently operated, the desired dose is actually injected by the injection device. In some embodiments, the operator may operate the dose setting mechanism by rotating a rotatable dose knob.
The injection mechanism is the part of the injection device which is used for injecting a desired dose once is has been set by means of the dose setting mechanism. The injection mechanism comprises a piston rod, and the piston rod is adapted to cooperate with a piston positioned in a cartridge. This typically takes place by causing the piston rod to move in an axial direction in the injection device during injection of a previously set dose. The piston rod is typically arranged in the injection device in such a manner that it abuts the piston arranged in the cartridge, and axial movement of the piston rod will therefore cause corresponding axial movement of the piston in the cartridge. Thereby drug is expelled from the cartridge and injected by the injection device. The injection mechanism preferably comprises a part which can be operated by an operator, e.g. an injection button or a release mechanism, e.g. for releasing energy which was previously stored in the spring device during dose setting. The piston driver is axially movable in a proximal direction relatively to the housing during dose setting, and it is axially movable in a distal direction relatively to the housing during injection of a set dose. In the present context the term ‘distal direction’ should generally be interpreted to mean a direction substantially along a longitudinal axis of the injection device, and towards an end being adapted to receive an injection needle. Similarly, in the present context the term ‘proximal direction’ should be interpreted to mean a direction substantially along the longitudinal axis of the injection device, and substantially opposite to the distal direction, i.e. away from the end being adapted to receive an injection needle. The proximal direction is preferably in a direction towards the position of the rotatable dose knob. However, in embodiments incorporating a flexible piston rod that is partly deflected away from an first axis, the remaining parts of the mechanism may be configured for operating along the deflected axis and the included references to distal and proximal directions will generally have to be redefined.
The piston driver is in some embodiments connected to the rotatable dose knob in such a manner that rotating the dose knob causes the piston driver to move axially in a proximal direction. Furthermore, the piston driver is preferably connected to the spring device in such a manner that moving the piston driver axially in a proximal direction causes energy to be stored in the spring device, and in such a manner that releasing energy stored in the spring device causes axial movement of the piston driver in a distal direction. Finally, the piston driver is preferably connected to the piston rod in such a manner that axial movement of the piston driver in a distal direction causes the piston rod to cooperate with the piston to cause a set dose to be delivered.
Retaining means may be arranged to prevent axial movement of the piston driver in a distal direction relatively to the housing during the setting of a dose. In the case that the piston driver is connected to the spring device and the piston rod as described above, the retaining means prevents the spring device from releasing the stored energy and cause the piston rod to cooperate with the piston to inject drug during dose setting. Thus, it is prevented that drug is accidentally spilled, and it is ensured that a correct dose is being set. Controlling this by axially retaining the piston driver rather than locking the piston rod directly has the following advantage. When a cartridge is empty and therefore has to be replaced, it is necessary to return the piston rod to an initial position corresponding to a full cartridge. In the case that axial movement of the piston rod in a distal direction during dose setting is prevented by directly locking the piston rod, e.g. by means of a locking item or a dosing member, it may be difficult to return the piston rod during replacement of the cartridge. This is particularly the case when the piston rod and the locking item/dosing member are engaged in such a manner that they tend to jam. However, according to the present invention axial movement of the piston rod in a distal direction is prevented by axially retaining the piston driver, and the risk of jamming the piston rod during replacement of the cartridge is thereby minimised, since the piston rod is allowed to return freely to the initial position.
The retaining means may be a dosing member being axially fixed relatively to the housing, and the dosing member may be adapted to be rotationally locked relatively to the housing during dose setting, and it may be adapted to be able to perform rotational movement relatively to the housing during injection of a set dose. According to this embodiment, when the dosing member is rotationally locked relatively to the housing, it axially retains the piston driver, i.e. it prevents the piston driver from performing axial movements in a distal direction. However, when the dosing member is allowed to perform rotational movement relatively to the housing it allows the piston driver to move axially in a distal direction.
The dosing member and the piston driver may be connected via mating threads formed on the piston driver and the dosing member, respectively. According to this embodiment the piston driver can be moved axially in a proximal direction by rotating the piston driver, thereby allowing it to climb the threaded connection between the dosing member and the piston driver. However, the threaded connection prevents that the piston driver is pushed in a purely axial movement in a distal direction as long as the dosing member is not allowed to rotate relatively to the housing. When the dosing member is subsequently allowed to rotate, the piston driver is allowed to move axially in a distal direction while causing the dosing member to rotate.
The injection device may further comprise a locking item being movable between a locking position in which it prevents the dosing member from rotating relatively to the housing, and an unlocking position in which the dosing member is allowed to rotate relatively to the housing. According to this embodiment the locking item is in its locking position during dose setting and in its unlocking position during injection of a set dose. Mating teeth may be formed on the dosing member and the locking item, respectively, and these mating teeth may engage when the locking item is in the locking position. When the locking item is moved into its unlocking position, the mating teeth are, in this case, moved out of engagement, thereby allowing mutual rotational movement between the dosing member and the locking item.
The locking item may be moved from the locking position to the unlocking position in response to operation of the injection mechanism. According to this embodiment, the locking item is automatically moved into the unlocking position when a user operates the injection mechanism. Thereby the injection device is automatically shifted from a state where a dose can be set into a state where a dose can be injected when the user operates the injection mechanism. Thereby the user only has to perform a single operation in order to cause a set dose to be injected, and the injection device is thereby very easy to operate.
As an alternative to a dosing member, the retaining means may, e.g., be or comprise a key and groove connection, one or more braking elements, one or more slidable locking elements, and/or any other means being suitable for axially retaining the piston driver as described above during dose setting.
The piston driver may be prevented from performing rotational movements relatively to the housing during injection of a set dose. According to this embodiment the piston driver moves in a purely axial manner relatively to the housing during injection of a set dose. This provides a very simple movement pattern, and the risk that the injection device jams during injection of a set dose is minimised.
The piston driver and the piston rod may be connected via mating threads formed on the piston driver and the piston rod, respectively. According to this embodiment, the piston driver is preferably moved along this threaded connection during dose setting. During injection the piston rod is preferably moved along the piston driver in an axial movement.
In a preferred embodiment the piston driver is threadedly connected to the piston rod as well as to a dosing member. For instance, the piston driver may comprise an inner thread arranged to engage an outer thread of the piston rod and an outer thread arranged to engage an inner thread of the dosing member. According to this embodiment, the piston rod, the piston driver and the dosing member may be arranged relatively to each other in such a manner that at least part of the piston driver surrounds at least part of the piston rod, and at least part of the dosing member surrounds at least part of the piston driver. As an alternative, the piston rod may be hollow, and the piston driver may, in this case comprise an outer thread arranged to engage an inner thread of the hollow piston rod.
The injection device may further comprise means for preventing rotational movement of the piston rod during dose setting. The means for preventing rotational movement of the piston rod may comprise a key and groove connection between the piston rod and a member being fixed relatively to the housing. Such a key and groove connection prevents the piston rod from rotating relatively to the housing, but relative axial movement is possible. The member is fixed relatively to the housing during normal operation, i.e. at least when a cartridge is inserted in the housing. However, the member may advantageously be fixed to the housing in such a manner that it is released, e.g. allowing rotational movements of the member relatively to the housing, during change of cartridge. Such an arrangement would allow the piston rod to be moved back during change of cartridge. This will be explained in more detail below with reference to the drawings.
Alternatively, the means for preventing rotational movement of the piston rod may comprise a third thread connection provided between the piston rod and a member being fixed relatively to the housing. The remarks set forth above relating to the member being fixed to the housing are equally applicable here. The third thread connection preferably has a pitch being directed in a direction which is opposite to the direction of the first thread. According to this embodiment the first thread connection between the dosing member and the piston rod and the third thread connection between the member and the piston rod in combination prevent rotational movement of the piston rod during dose setting, and thereby prevent axial movement of the piston rod during dose setting.
The piston driver may be connected to the dose knob via a key and groove connection. In this case the piston driver is simply rotated along with the dose knob during dose setting, and the dose knob and the piston driver may be allowed to perform mutual axial movements.
The operation of the dose setting mechanism causes energy to be stored in a spring device, and the injection mechanism is driven by releasing energy previously stored in said spring device during dose setting. The spring device may, e.g., comprise a spring, such as a compressible spring, an extension spring or a torsion spring, or it may be or comprise any other suitable means capable of storing mechanical energy and subsequently releasing the stored energy. Such an injection device is very easy to use for persons having poor dexterity or low finger strength, e.g. elderly people or children, because only a relatively small force needs to be applied by the user in order to inject a set dose, since the necessary mechanical work is carried out by the spring device. Furthermore, in injection devices where the injection is performed by releasing energy previously stored in a spring device, the piston rod is normally moved during injection by applying a pushing force to the piston rod in a substantially axial direction.
The injection device may further define a release mechanism for releasing energy stored in the spring device, thereby causing a set dose to be injected. The release mechanism may, e.g., comprise a release button which the user operates. The release mechanism is preferably axially movable, and it may be operable by a user pressing a release button in a substantially axial direction. In this case the release button may be integral with the dose knob.
In a second aspect, the invention relates to a method of assembling an injection device incorporating a drive mechanism in any of the forms as described above.
Such method may comprise the steps of:
a) providing the spring device, the piston driver and the counter-element,
b) forming a drive mechanism subassembly by arranging the piston driver, the spring device and the counter-element relative to each other and operating the piston driver and the counter-element relatively to each other so that the spring device is tensioned,
c) moving the piston driver and the counter-element relatively to each other into a state where the tension of the spring device exceeds the tension of the spring device obtained when in the maximum dose setting state,
d) activating the releasable interlock for maintaining the piston driver and the counter-element in an interlocked state wherein the relative axial position between the piston driver and the counter-element is fixed and wherein the spring device is in a tensioned state.
In accordance herewith, the releasable interlock is activated only when the piston driver and the counter-element are positioned relatively to each other to assume a state where the tension of the spring device exceeds the tension of the spring device obtained when in the maximum dose setting state. Hence, the interlock mechanism cannot interfere with the operation of the dose setting mechanism during subsequent operations, e.g during use of the assembled injection device such as during dose setting operations and during dose expelling operations.
The assembling method may further comprise the step of providing a housing, and, subsequent to step c): the steps of,
e) positioning the assembly relative to the housing, and
f) releasing the interlock thereby enabling the piston driver and the counter-element to be axially moveable relative to each other between the minimum dose setting state and the maximum dose setting state.
Further, the method of assembling the injection device as defined above may further comprise that in step a), i.e. providing the spring device, the piston driver and the counter-element, these elements may be provided such that:
The assembling method may further comprise the step, subsequent to step e) of:
g) operating the piston driver and the counter-element relative to each other for setting the dose between the minimum dose setting state and the maximum dose setting state or vice versa.
As noted above, any of the details, embodiments and forms described in connection with the first aspect may be used in the assembling method according to the second aspect.
The invention will now be described in further detail with reference to the accompanying drawings in which:
a shows a shows cross sectional side view and
a and 2b shows similar views of the injection device of
a and 3b shows similar views of the injection device of
a and 4b shows similar views of the injection device of
a shows a schematic representation of a sensor system associated with a piston driver in the form of a dosage tube,
b shows a schematic representation of a sensor system associated with a locking nut,
a and 12b represent tables of sensor values of the sensor systems of
a, 15b and 15c show side views of selected components of the drive mechanism according to the invention during manufacture respectively representing a first, a second and third assembly state, and
a, 16b and 16c show cross sectional side views of the drive mechanism during manufacture respectively representing a fourth, a fifth and a sixth assembly state.
The drive mechanism included in injection device 1 is adapted to operate in two mechanical operational modes, respectively designated Dose Setting Mode and Dosing Mode. In Dose Setting Mode, dose setting may be performed by dialing up and down a manually operable dose setting member. In this mode, the piston rod of the device is held stationary so that no dose will be expelled. In Dosing Mode, altering an already set dose is prevented while the expelling of an already set dose can be performed. The mechanism may include a mechanical transition zone between the Dose Setting Mode and the Dosing Mode, the transition zone being designated Safe Mode. Safe Mode is a zone ensuring that neither dose setting nor dose expelling can be performed.
In
The injection device 1 of
In the injection device 1, the dose setting member forms a dose knob 5. When it is desired to set a dose the dose knob 5 is rotated. The dose knob 5 is rotationally locked to injection button 24 via a first spline connection. The injection button 24 is rotationally locked to a dose setting item via a second spline connection. In the following the dose setting item will be referred to as a counter-element 15. In the shown embodiment, the counter-element 15 is rotationally locked to the piston driver 6 via a third spline connection. Accordingly, when the dose knob 5 is rotated, the piston driver 6 is rotated along. Due to the threaded connection between the piston driver 6 and the locking nut 8, and because the locking nut 8 is prevented from rotating, due to the engagement between teeth 10, 11, the piston driver 6 is thereby moved axially in a proximal direction relative to the locking nut 8, and in a spiraling movement. Simultaneously, the piston driver 6 climbs along the piston rod 7 which remains fixed relative to the housing component 2.
In the shown embodiment, the injection device includes a spring device in the form of a helical compression spring 19 arranged internally between the piston driver 6 and the counter-element 15. During dose setting, the axial movement of the piston driver 6 causes compressible spring 19 to be compressed, i.e. energy is stored in the compressible spring 19. The distance traveled by the piston driver 6 corresponds to the dose being set.
An initially set dose may be dialed down fully or partly by reversing the direction of rotation of dose knob 5. Such dialing down may be performed all the way to the zero dose dial position to thereby return the piston driver 6 to the initial relative rotational position between the piston driver 6 and the locking nut 8. The injection device 1 may include an indexing mechanism whereby the dose knob 5 is configured to move in discrete rotational steps corresponding to the desired dose increments, i.e. providing a number of pre-defined rest-positions which may correspond to the number of locking positions between locking nut 8 relative to the housing 2. Referring to
In some embodiments, the force originating from the compressible spring 19, when compressed, may tend to automatically dial down an initially set dose. However, the inclusion of an indexing mechanism may prevent this by adequately designing the indexing mechanism to provide reluctance against self-returning of the dose knob 5.
a and 2b show the injection device 1 of
Comparing
In
When it is desired to inject the set dose, the injection button 24 is pushed in a distal direction, i.e. towards the housing component 2. The injection button 24 is connected to the locking item 12 via connecting part 25. Accordingly, pushing the injection button 24 causes the locking item 12 to move along in a distal direction, thereby moving the teeth 10, 11 out of engagement, allowing the locking nut 8 to rotate. The injection button 24 is configured in such a manner that it automatically returns to its initial distal position when external pressure acting on the injection button 24 is released. In the shown embodiment this is obtained by means of click spring 17.
The locking nut 8 may be mounted relative to the housing by means of a ball bearing or similar to provide a low-frictional rotation of the locking nut 8 during dosing.
a and 3b show the injection device 1 of
The compressed spring 19 pushes against the piston driver 6, thereby urging it in a distal direction. Since the locking nut 8 is now allowed to rotate, the piston driver 6 is allowed to move in a distal direction, while forcing the locking nut 8 to rotate due to the connection between the outer thread 22 of the piston driver 6 and the inner thread 23 of the locking nut 8. The energy stored in the compressed spring 19 will cause the piston driver 6 to perform this movement. Due to the connection between the inner thread 21 of the piston driver 6 and the outer thread 14 of the piston rod 7, the piston rod 7 is moved along in this movement. In use of the injection device 1, the piston rod 7 is arranged in abutment with a piston (not shown) arranged in a cartridge. Accordingly, moving the piston rod 7 as described above causes the set dose of drug to be expelled from the injection device 1. The injection movement may be halted at any time during injection by releasing the injection button 24. The dose movement may be continued by once again pushing the injection button 24 in the distal direction.
In the shown embodiment, the injection button 24 is provided with a plurality of axially extending teeth (not referenced) arranged to releasably engage corresponding teeth (not referenced) formed in the housing component 2 (cf.
a and 4b show the injection device 1 of
In accordance with the above, as the locking nut 8 only rotates during the injection process, i.e. from the start of the dosing movement of piston driver 6 till the end of dose state is reached, the locking nut 8 performs as a dosing member for metering doses expelled from the device.
In the shown embodiment, the piston rod 7 is rotationally locked with respect to the housing component 2 during dose setting and injection operations. However, in an alternative embodiment, the piston rod 7 may be configured to rotate during the dosing movement in a manner as described in WO 2006/114395. As known in the art, the rotational lock or the rotational guiding of piston rod 7 relative to housing component 2 may be provided by means of a locking disc 9 which engages a track or thread on piston rod 7 and which is locked relative to the housing during the dose setting and dose injection process.
Turning now to
In an exemplary embodiment and as identified in
In the shown embodiment, the sensor arrangements 40, 50, 60 and 70 are formed as conductive switch based sensors which are coupled to an electronic control circuit incorporating a processor and being powered by a power source. In
The first sensor arrangement 40 used for detecting a set dose is based on a principle of detecting the rotational motion between the piston driver 6 and the switch frame 80. As the counter-element 15 rotates together with the piston driver 6 and as the counter-element 15 is mounted axially fixed in the device 1, the counter-element 15 is utilized for detecting rotational movements during a dose setting operation. By keeping track of the rotation of counter-element 15 it is possible to determine the dose set. The sensor arrangement 40 is implemented as a Gray code pattern (referenced first Gray code pattern 41) which is fixedly arranged relative to counter-element 15. The first Gray code pattern 41 is formed as a cylindrical drum being swept by a set of contact arms comprised within the switch frame 80 as the piston driver 6 is rotated. Hence, it is possible to detect direction and keep count of the net dose set. The set of contact arms are formed as a group of eight contact arms below referred to as the first group of contact arms 42.
The second sensor arrangement 50 used for detecting the amount dosed is based on the same principle utilizing a first Gray code pattern 51 provided as a cylindrical drum fixedly arranged relative to the locking nut 8. This Gray code pattern 51 is being swept by a second group of contact arms 52 which in the shown embodiment consist of six contact arms.
The first and second gray code patterns 41 and 51 are provided as galvanically conducting patterns having a series of electrically insulating fields disposed thereon. Alternatively, the first and second Gray code patterns may be formed as a generally electrically insulating base material having a plurality of galvanically conducting fields disposed thereon. In the shown embodiment the code patterns 41 and 51 are provided as metallic or metallized sleeves which are fixedly attached to counter-element 15 respectively to locking nut 8.
In alternative embodiments, the first Gray code pattern 41 and/or the second Gray code pattern 51 may be provided as unitarily formed into counter-element 15 respectively to locking nut 8, such as being fabricated using MID technology (Molded Interconnect Devices). Typical known methods for producing conductor tracks on three-dimensional products include, for example, two-component injection molding, hot-stamping, mask-exposure methods and thin-film insert molding.
In a particular embodiment, the first Gray code pattern 41 and/or the second Gray code pattern 51 are formed by Laser Direct Structuring (LDS) whereby the counter-element 15 and/or the locking nut 8 are formed by an initially non-conductive doted thermoplastic material. The thermoplastic material on which the conductive areas are to be formed are activated by means of targeted laser radiation and then metallized in a chemical bath. Typically, the LDS process involves forming a first copper layer on the activated areas by means of a chemical metal-deposition process in a current-free copper bath, then a chemical nickel layer is applied electroless on top of the copper layer and finally a flash gold layer is applied electroless on top of the nickel layer to provide a corrosion resistant surface.
In this embodiment, and as indicated in
The galvanic copper layer is optional and provides for levelling the finished product to obtain a particular smooth surface of the conductive areas of the Gray code pattern. In other embodiments, this layer may be omitted.
The counter-element 15/Gray code 41 may be manufactured by a similar process as described above in connection with the locking nut 8/Gray code pattern 51, including the injection-molding of a thermoplastic support material to provide the surface geometries 15b to cooperate with corresponding surface geometries 16b of knurled disc 16 (see
By the above process a particular durable surface for the Gray code pattern is achieved which, especially for switch devices having contact elements wiping the surface of the code surface (containing the non-conductive and conductive areas), provides superior wear resistance, durability and electrical conductivity. Hence, in the particular application for the locking nut 8 above and/or for the counter-element 15, a particular reliable encoder solution is provided.
As for the contact elements, the state of each individual contact arm is detected by the switch sensor interface of the electronic control circuit and the information is processed by an algorithm implemented in the switch sensor interface. In this way the switch sensor interface counts the amount set, counts the amount dosed, and presents the value of these counters to the processor for further processing the data.
Electrically the sensors are configured as switches connected to ground, and the corresponding inputs to the electronic control circuit are held high by pull-up resistors to ensure a well-defined signal level. An open switch will not consume any power, but a closed switch will consume power as its pull-up resistor connects supply voltage and ground. A power conservation strategy is implemented that disables the pull-up resistors for the switches that are closed in the same manner as described in WO 2010/052275.
Such sensor system will not consume power continuously, but with this strategy only transitions that results in switches being closed can be detected. A switch that opens will not generate a rising voltage on its corresponding input since the pull-up resistor for that input has been disabled.
Further,
The first Gray code pattern 41 is schematically represented in
The first and second Gray code patterns have a code length of 8 codes (Index 0 through Index 7) and are each disposed within a 120 deg. span pr. sequence. Hence, for each full revolution that the counter-element 15 and locking nut 8 undergoes, the contact arms will swipe the respective Gray codes three times.
Each of the first and second Gray code patterns comprises separate tracks formed as a number of circular bands. A first circular band defines a continuous electrically conducting ground pattern (designated Ground SW). A set of two contact arms provides for redundant galvanic coupling to the first circular band of the Gray code patterns. The Gray code patterns further comprises two circular patterned bands each defining generally isolating fields of angular width 75 deg. spaced apart by 45 deg. conductive traces. The first of the two circular patterned bands is offset by an angle of 15 deg relative to the other of the two circular patterned bands. Contact arms designated SW 1, SW 2 are arranged to cooperate with the first circular patterned bands and contact arms designated SW 3 and SW 4 are arranged to cooperate with the other. The contact arms SW 1 and SW 2 are positioned 30 deg. apart. Also the contact arms SW 3 and SW 4 are positioned 30 deg. apart.
The first Gray code pattern further includes a further track forming a circular band of alternating conducting and isolating fields each having an angular width of 15 deg. This circular band is provided as a wake-up track. Also for this track a set of two contact arms spaced 30 deg. apart swipes this circular band and provides for redundant electrical connection.
a and 12b show table values of the first and the second sensor arrangement for each of the sequences Index 0 through Index 7 for a Gray code lay-out as shown in
As noted above, a switch that opens will not generate a rising voltage on its corresponding input since the pull-up resistor for the input has been disabled. Hence, having a Gray code pattern as defined in
For the second Gray code pattern 51 which is associated with the locking nut 8 another implementation is chosen. Here all pull-up resistors are enabled whenever the fourth sensor arrangement 70 detects that the injection button 24 is pressed in; and deactivated when the fourth sensor arrangement 70 detects that the injection button is in its non-depressed state. In this way the second sensor arrangement 50 associated with the locking nut 8 and relating to dosing is only consuming power when the device 1 is actually in Dosing Mode.
As noted above, the third sensor arrangement 60 provides information as to whether the piston driver 6 is within a pre-defined axial distance from the position the piston driver 6 assumes at the end of dose position. In one form, the third sensor arrangement 60 may be based on a simple principle of two contact arms being connected by a conductive circular band 61 arranged fixedly relative to piston driver 6 wherein the conductive circular band is provided between adjacent regions of electrically insulating material. When the conductive circular band is not in the proximity of its end of dose position, i.e. further away than 0 to 7 index positions from the end of dose position the conductive circular band connect the two contact arms and consequently the switch will remain in an open state. When the piston driver 6 reaches a point in the proximity of its end of dose position (an arbitrary point that is within 0-7 index positions from the end of dose position), the cylinder will connect the switch arms and cause the third sensor arrangement 60 to enter a closed state.
In the shown embodiment, the third sensor arrangement 60 is provided as three contact arms 62 cooperating with conductive cylinder 61, providing two separate state changes occurring at two mutual offset axial positions of piston driver 6 relative to the locking member 8. Such configuration provides increased reliability in safely detecting whether or not the piston driver 6 is within close proximity to its end of dose position.
Electrically, the sensor is configured as a switch connected to ground, and the corresponding input to the electronic control circuit is held high by a pull-up resistor to ensure a well-defined signal level.
The fourth sensor arrangement 70 is based on a switch being closed. In the depicted embodiment a contact arm 72 is manipulated by a flange (not shown) on the connecting part 25. When the injection button is not activated (not pushed in) the flange will not activate the switch and consequently the switch will remain in an open state. When the injection button 24 is pushed in, the flange will perform an axial movement and cause the fourth sensor arrangement 70 to enter a closed state. Electrically the sensor is configured as a switch connected to ground, and the corresponding input to the electronic control circuit is held high by a pull-up resistor to ensure a well-defined signal level.
In other embodiments, the third sensor arrangement 60 and/or the fourth sensor arrangement 70 may include a similar manufacturing process using LDS as described above having a hard gold layer provided on the outer surface. For example, the conductive cylinder 61 may be disposed on a non-conductive thermoplastic support either integrally formed with piston driver 6 or fixedly attached to piston driver 6, where the above described metal layer distribution (see
The mechanical coupling between the piston driver 6 and the locking nut 8 during dose setting (dialing up and dialing down) as well as during dosing means that the first and second Gray code patterns 41 and 51 will always end up at the same relative rotational position after a complete dosing has taken place. Hence, in the end of dose state of the device 1, the index of the first Gray code pattern 41 will be the same as the index of the second Gray code pattern 51 provided that the two Gray code patterns during manufacture have been aligned corresponding to an alignment in the end of dose state of the device 1.
As noted above, the dose setting mechanism may be designed to cover a dosable range that may be chosen as 80 or 100 index positions. Due to this and due to the fact that the shown embodiment utilizes Gray code patterns which only provide an absolute detection of the rotational position within a sequence of 8 rotational positions (corresponding to 120 deg. of rotation) the monitoring during operation of the device 1 is based on counting the number of full sequences as well as fractional sequences of rotation performed during relative rotational movement between the piston driver 6 and the locking nut 8. Hence, there will be a multitude of relative rotational positions between piston driver 6 and locking nut 8 where the signals from the first and second sensor arrangements are the same. Likewise, there will be a number of relative rotational positions between piston driver 6 and locking nut 8 which correspond to the relative rotational position at the end of dose state of the device 1. Therefore, the synchronization between the first and the second sensor arrangements are being monitored.
In the above sensor configuration, the exact adjusted dose size and/or the total amount of an expelled dose will not be detectable when basing the monitoring solely on instantaneous data provided by the first sensor arrangement 40 and the second sensor arrangement 50. Should one or more interrupts be missed during operation of the device there will be a risk that the synchronization between the electronic sensor system and the mechanical system may fail.
In order to ensure synchronization between the mechanical system and the electronic system, the information provided by the third sensor arrangement 60 is utilized which provides a detection that the relative rotation between piston driver 6 and locking nut 8 is within 1 sequence (0-7 Index positions) from the end of dose state. Combining this information and the differential information from the first sensor arrangement 40 and the second sensor arrangement 50 a detection of the exact end of dose state is deductible. If a discrepancy should occur between the continuous monitoring and instantaneous information obtained from the sensor arrangements 40, 50, 60 and 70, the electronic control circuit will detect this as a failure and provide a warning indication to the user of the device. If the error is one of a recoverable kind, the device may be reset by means of the signals from the first sensor arrangement 40, the second sensor arrangement 50 and the third sensor arrangement 60 and the synchronization between the mechanical system and the electronic system may be recovered. If the error is irrecoverable, a warning as to this instance may be indicated to the user.
Due to the rotational stop surfaces of the piston driver 6 relative to the locking nut 8 at the end of dose state, the relative position are well defined and thus allows the device to reset itself during normal operation, e.g. during operation of the injection button 24 and/or the dose knob 5. Hence, the device may be so adapted that the first and the second sensor arrangements synchronizes automatically when the device is in the end of dose state.
The above described sensor values are used for estimating the dose as set and the dose as expelled so as to provide an indication on a display of the device (not shown). In the shown embodiment, during a dosing operation, the display may be configured to continuously show the part of a set dose that remains to be injected, e.g. as defined by the display refresh rate.
The electronic control circuit of the injection device 1 may further include a memory circuit adapted to hold information relating to a plurality of set and/or injected doses and the timing information relating to each such dose. Hereby the dosing history may be browsed through for example by utilizing the injection button 24 as a means for stepping through the injection history.
The electronic control circuit of the injection device 1 may in addition, or as an alternative, be provided with means for communicating the contents of the memory to an external apparatus, such as a personal computer, a mobile communication terminal such as a SmartPhone or such as a glucose meter (BGM/CGM). Such means for communication may be provided by means of an optical port such as an IR port, an RF communication antenna such as for communicating via Bluetooth or NFC, or via cable connection, etc.
Now turning to
As shown in
It is to be noted that
The piston driver 6 is provided with radially extending protrusions 6c positioned at the proximal end of the piston driver (see also
As shown in
As apparent from
As shown in
Hereafter, as shown in
It is to be noted that the dose setting and injection mechanisms described above only relate to a few particular embodiments according to the invention. In accordance with the design aspects described above, other drive mechanisms such as the drive devices disclosed in US 2007/0088290 A1 may be utilized in accordance with the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11192105.2 | Dec 2011 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/074683 | 12/6/2012 | WO | 00 | 6/2/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61568218 | Dec 2011 | US |
