Sensor arrangement for an injection device

Abstract

The disclosure relates to a sensor arrangement for an injection device to determine an axial position of at least one device component of the injection device inside a housing of the injection device. The sensor arrangement includes an elongated member located inside the housing, extending in an axial direction and having at least a first section and a second section of different magnetization. The first and second sections are separated in the axial direction. The sensor arrangement also includes at least one magnetic sensor element attached to the housing to detect the axial position of at least one of the first and second sections.

Claims

1. A sensor arrangement for an injection device, the sensor arrangement comprising: an elongated member arrangeable inside a housing of the injection device such that the elongated member extends in an axial direction relative to the housing, the elongated member having at least a first section of a first magnetization and a second section of a second magnetization, wherein a direction of the first magnetization differs from a direction of the second magnetization, and wherein the first section and the second section are separated in the axial direction; and at least one magnetic sensor attachable to the housing to detect an axial position of at least one of the first section and the second section of the elongated member; wherein the elongated member is mechanically engaged with a device component that is axially displaceable along the elongated member and relative to the housing of the injection device, and wherein the device component is configured to attenuate or to amplify a magnetic field of the elongated member.

2. The sensor arrangement according to claim 1, wherein the first section and the second section are separated in the axial direction in a non-overlapping manner.

3. The sensor arrangement according to claim 1, wherein the elongated member comprises a helical pattern of differently magnetized sections.

4. The sensor arrangement according to claim 1, wherein the elongated member comprises a third section of a third magnetization and a fourth section with a fourth magnetization, wherein the second section is located axially between the first section and the third section, and wherein the third section is located axially between the second section and the fourth section.

5. The sensor arrangement according to claim 4, wherein the direction of the first magnetization is opposite to a direction of the third magnetization, wherein the direction of the second magnetization is opposite to a direction of the fourth magnetization, and wherein the direction of the first magnetization extends at a predefined non- zero angle with regard to the direction of the second magnetization.

6. The sensor arrangement according to claim 1, wherein the at least one magnetic sensor is arranged in a sensor housing attachable to the housing of the injection device.

7. The sensor arrangement according to claim 1, comprising a magnetic sensor array having multiple sensor elements separated from each other in the axial direction, the at least one magnetic sensor being one or more of the multiple sensor elements.

8. The sensor arrangement according to claim 1, wherein the elongated member comprises a magnetized coating.

9. The sensor arrangement according to claim 1, wherein the device component is ferromagnetic or ferrimagnetic.

10. The sensor arrangement according to claim 1, wherein the device component is permanently magnetized.

11. The sensor arrangement according to claim 1, wherein the device component magnetically interacts with the elongated member.

12. The sensor arrangement according to claim 1, wherein the device component is threadedly engaged with the elongated member, and is rotatably fixed to the housing but is slidably displaceable relative to the housing.

13. The sensor arrangement according to claim 1, wherein the device component is threadedly engaged with the housing and is rotatably fixed to the elongated member but is slidably displaceable relative to the elongated member.

14. The sensor arrangement according to claim 1, wherein the device component is a last dose limiting member of a drive mechanism of the injection device, wherein the last dose limiting member prevents setting a dose on the injection device that exceeds an amount of medicament left in a cartridge of the injection device.

15. The sensor arrangement according to claim 1, wherein the sensor arrangement is part of a drive mechanism of the injection device, and wherein the elongated member is a piston rod, a dose indicator, or a drive sleeve of the drive mechanism.

16. An injection device for setting and injecting of a dose of a liquid medicament, comprising: a housing to accommodate a cartridge filled with the liquid medicament; a drive mechanism comprising a piston rod to operably engage with a piston of the cartridge; and a sensor arrangement attached to the housing or arranged inside the housing, the sensor arrangement comprising: an elongated member located inside the housing, extending in an axial direction and having at least a first section and a second section, the first section having a different magnetization than the second section, the first section and the second section being separated in the axial direction, and at least one magnetic sensor element attached to the housing to detect an axial position of at least one of the first section and the second section of the elongated member; and wherein the elongated member is mechanically engaged with a device component that is axially displaceable along the elongated member and relative to the housing of the injection device and wherein the device component is configured to attenuate or to amplify a magnetic field of the elongated member.

17. The injection device according to claim 16, wherein the elongated member is mechanically engaged with a device component that is axially displaceable along the elongated member, wherein the device component is threadedly engaged with the elongated member, and is rotatably fixed to the housing but is slidably displaceable relative to the housing.

18. The injection device according to claim 16, further comprising the cartridge filled with the liquid medicament.

19. A sensor arrangement for an injection device, the sensor arrangement comprising: an elongated member arrangeable inside a housing of the injection device such that the elongated member extends in an axial direction relative to the housing, the elongated member having at least a first section of a first magnetization and a second section of a second magnetization, wherein a direction of the first magnetization differs from a direction of the second magnetization, and wherein the first section and the second section are separated in the axial direction; and wherein the elongated member comprises a third section of a third magnetization and a fourth section with a fourth magnetization, wherein the second section is located axially between the first section and the third section, and wherein the third section is located axially between the second section and the fourth section and wherein the direction of the first magnetization is opposite to a direction of the third magnetization and wherein the direction of the second magnetization is opposite to a direction of the fourth magnetization, wherein the directions of the first magnetization, the second magnetization, the third magnetization and the fourth magnetization extend at predefined non-zero angles with regard to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, an embodiment of the display arrangement, the drive mechanism and the injection device is described in detail by making reference to the drawings, in which:

(2) FIG. 1 schematically shows an injection device of pen-injector type,

(3) FIG. 2 shows a first embodiment of a sensor arrangement to determine an axial position of at least one device component,

(4) FIG. 3 shows another embodiment of the sensor arrangement,

(5) FIG. 4 schematically shows the elongated member with four axial sections of different magnetization and

(6) FIG. 5 schematically shows the sensor arrangement implemented as a supplemental device attached to the housing of the injection device.

DETAILED DESCRIPTION

(7) In FIG. 1 an injection device 100 is schematically illustrated in an exploded view. The injection device 100 is of pen-injector type. It comprises an elongated housing 102, also denoted as body. The housing 102 is of elongated shape and extends in an axial distal direction 1 and opposite in an axial proximal direction 2. At its distal end the housing 102 is connected to a cartridge holder 104. The housing 102 as well as the cartridge holder 104 are of tubular shape. The cartridge holder 104 is configured to accommodate a cartridge 122 while the housing 102 is configured to accommodate a drive mechanism 103 comprising numerous mechanically interacting components by way of which a piston 126 of the cartridge 122 is displaceable in distal direction 1 in order to expel a medicament from the interior of the tubular-shaped barrel 124 of the cartridge 122.

(8) The cartridge 122 further comprises a pierceable seal 128 at its distal end, which seal is penetrable or pierceable by a double-tipped injection needle of a needle assembly 106. As indicated in FIG. 1, the needle assembly 106 is releasably attachable to a distal end of the cartridge holder 104. As further shown in FIG. 1, the distal socket of the cartridge holder 104 comprises an outer thread to threadedly engage with a correspondingly-shaped inner thread of the needle assembly 106. The injection needle of the needle assembly 106 is initially covered with an inner needle cap 108. The entire needle assembly 106 is furthermore covered and equipped with an outer needle cap 110. Prior to conduct an injection procedure, outer and inner needle caps 110, 108 are to be detached from the needle assembly 106. The injection device 100 further comprises a protective cap 112 releasably attachable to the assembly of cartridge holder 104 and housing 102. Typically, the protective cap 112 covers the cartridge holder 104 while it is attached to the body 102.

(9) The cartridge holder 104 is either of transparent material or comprises an inspection window to visually inspect the medicament located inside the barrel 124 of the cartridge 122. The cartridge 122, in particular its barrel 124 is typically made of a vitreous material, such like glass. The barrel 124 may be also made of a plastic material being substantially inert to the medicament located therein.

(10) The drive mechanism 103 at least comprises a dose indicator 140 rotatably mounted inside the housing 102 and having numerous indicia or numbers printed on its outer circumference that are visible through a dosage window 116. The drive mechanism 103 further comprises a drive sleeve 150 operably engaged with the dose indicator 140 as well as with the piston rod 130. The piston rod 130 extending in axial direction comprises a radially widened pressure piece 132 at its distal end to exert distally directed pressure to the proximally facing portion of the piston 126 of the cartridge 120. In this way, a predefined amount of medicament, typically a dose of appropriate size is dispensable via the needle assembly 106 in fluid communication with the interior of the cartridge 122.

(11) Furthermore, the drive mechanism 103 comprises a dose dial 114 that is rotatable in a dose incrementing direction and eventually also in a dose decrementing direction. Dialing of the dose dial 114 in either direction relative to the housing 102 allows a user to individually set and modify a dose of the medicament of required size. At the proximal end of the injection device 100 there is located an injection button 120. Depressing of the injection button 120, typically in distal direction 1 induces or triggers a dispensing action. During dispensing the dose indicator 140 typically returns into a zero dose configuration and the piston rod 130 drives in distal direction to displace the piston 126 further in distal direction for the purpose of dose dispensing. Generally, the drive mechanism 103 as shown here resembles or is even identical to the drive mechanism as disclosed in WO 2004/078239A1, WO 2004/078240A2 or WO 2004/078241 A1 the entirety of which is herein incorporated by reference.

(12) In FIG. 5 a sensor arrangement 10 to determine an axial position of at least one component of the injection device 100 is schematically illustrated. In this embodiment the sensor arrangement 10 is implemented as a supplemental device having a sensor housing 50 that is attached or which is generally attachable to the an outside facing sidewall portion of the housing 102 of the injection device 100. As indicated in FIG. 5, the sensor housing 50 is connected to the housing 102 by means of a fixation 52. In the embodiment as shown in FIG. 5 the sensor arrangement 10 comprises at least a magnetic sensor 20 having several sensor elements 22 arranged along the axial direction. Hence, the various sensor elements 22 are arranged side-by-side or adjacently in axial direction so as to form an axially elongated sensor array 24.

(13) The sensor arrangement 10 typically comprises a sensor control 40 that is connected to all of the sensor elements 22. The sensor control 40 is operable to process the individual signals obtainable from the various sensor elements 22. The sensor control 40 is operable to provide an output to a processor 44 of the sensor arrangement 10, which processor 44 is operable to calculate an axial position of at least one device component 12, 212, and/or 30 of the injection device 100. Furthermore, the sensor arrangement 10 is equipped with a power supply, typically in form of an electric battery 42. Alternatively, the sensor arrangement 10 may be equipped with some other type of electrical power supply such like solar cells.

(14) Moreover, the sensor arrangement 10 may be further equipped with a display 46 in order to visualize a particular status of the injection device 100. Additionally or alternatively, the sensor arrangement 10 comprises a communication unit 48 by way of which an axial position of the at least one device component determined by the processor 44 can be communicated to any further device. The communication unit 48 may provide wired or wireless data transmission to a further external device. The communication unit 48 may be provided with standard communication protocols, such like Bluetooth, RFID or other radio-frequency operated wireless transmission protocols.

(15) In FIG. 2, a first embodiment of the sensor arrangement 10 is shown in greater detail. There, a longitudinal cross-section through the injection device 100 is provided. The sensor arrangement 10 comprises an elongated member 12 which elongated member 12 may be formed by the piston rod 130, by the dose indicator 140 or by the drive sleeve 150 of the drive mechanism 103 of the injection device 100. The elongated member 12 is axially displaceable inside the housing 102. As indicated in FIG. 2, the elongated member 12 is virtually divided into a number of sections 12a, 12b, 12c, 12d, 12e that are located axially adjacent. The sections 12a, 12b, 12c, 12d are of different magnetization as indicated by the arrows, points and crosses of the various sections 12a, 12b, 12c, 12d as shown in FIG. 2. In addition, the sensor arrangement 10 comprises at least one magnetic sensor element 22.1, 22.2, 22.3 only to mention a few. Typically the magnetic sensor 20 comprises a sensor array 24, formed by a longitudinal row of individual magnetic sensor elements 22.1, 22.2, 22.3 and so on. By means of the sensor array 24, the actual axial position of the elongated member 12 is precisely detectable. Moreover, also a movement of the elongated member 12 in axial direction 1 or 2 is directly detectable and quantitatively measurable by means of the sensor array 24.

(16) In FIG. 4, the different magnetizations of various sections 12a, 12b, 12c, 12d, 12e is shown in further detail. The elongated member 12 may be of substantially tubular elongated shape and the various sections 12a, 12b, 12c, 12d, 12e all extend over the entire cross-section of the elongated member in a plane substantially perpendicular to the axial elongation thereof. As shown in FIG. 4, the first section 12a has a magnetization pointing upwards. The second section 12b located axially adjacent to the first section 12a features a magnetization pointing to the right. A third section 12c adjacent to the second section 12b has a magnetization pointing downwards and a fourth section 12d axially adjacent to the third section 12c has a magnetization pointing substantially to the left. The fifth section 12e axially adjacent to the fourth section and has a magnetization pointing upwardly, like the first section 12a. In other words, the magnetization of adjacently arranged sections 12a, 12b, 12c, 12d, 12e of the elongated member 12 changes by a constant angle, presently by about 90°. The spiral or helical-shaped magnetization of the elongated member is similar to the one of a Halbach array. Moreover, the elongated member may be implemented as a Halbach array.

(17) In the embodiment according to FIG. 3 the sensor arrangement 10 comprises a slightly different elongated member 212. Also, this elongated member 212 may be implemented as one of a piston rod 130, a dose indicator 140 or a drive sleeve 150. The elongated member 212 is also segmented into various sections 212a, 212b, 212c, 212d, 212e and so on of different magnetization as indicated in FIG. 3. In contrast to the embodiment as described with respect to FIG. 2 the elongated member 212 as shown in FIG. 3 comprises an outer thread 216 by way of which the elongated member 212 is threadedly engaged with a second member 30. The second member 30 has an inner thread 36 and is hence axially displaceable relative to the elongated member through a rotation of the elongated member 212 relative to the second member 30.

(18) Typically, the elongated member 212 is rotatable relative to the housing 102 while the second member 30 is rotationally locked to the housing 102 but is further axially displaceable relative to the housing 102. Typically, the second member 30 modifies the magnetic field of the elongated member 212. For this purpose the second member 30 may be ferromagnetic or ferrimagnetic. In this case, the present and the axial position of the second member 30 is easily detectable by the array of sensor elements 22.1, 22.2, 22.3. Alternative to a ferromagnetic or ferrimagnetic implementation of the second member it is also conceivable that the second member exhibits a paramagnetic or diamagnetic behavior that is detectable by the sensor array 24.

(19) In order to obtain a predefined magnetized pattern of the elongated member, it is conceivable that the elongated member 12, 212 comprises a magnetized or magnetizable material in its bulk. Alternatively it is conceivable that the elongated member 12, 212 is provided with a magnetized or magnetizable coating 14, 214, which coating is magnetizable in axial sections in different directions.

LIST OF REFERENCE NUMBERS

(20) 1 distal direction

(21) 2 proximal direction

(22) 10 sensor arrangement

(23) 12 elongated member

(24) 12a,b,c,d,e section

(25) 14 coating

(26) 20 sensor

(27) 21.1 sensor element

(28) 22.2 sensor element

(29) 22.3 sensor element

(30) 24 sensor array

(31) 30 second member

(32) 36 thread

(33) 40 sensor control

(34) 42 power supply

(35) 44 processor

(36) 46 display

(37) 48 communication unit

(38) 50 sensor housing

(39) 52 fixation

(40) 100 injection device

(41) 102 housing

(42) 103 drive mechanism

(43) 104 cartridge holder

(44) 106 needle assembly

(45) 108 inner needle cap

(46) 110 outer needle cap

(47) 112 protective cap

(48) 114 dose dial

(49) 116 dosage window

(50) 120 injection button

(51) 122 cartridge

(52) 124 barrel

(53) 126 piston

(54) 128 seal

(55) 130 piston rod

(56) 132 pressure piece

(57) 140 dose indicator

(58) 150 drive sleeve

(59) 212 elongated member

(60) 212a,b,c,d,e section

(61) 214 coating

(62) 216 thread