An injection device having a needle detection function

Abstract

The present invention relates to an injection device. The injection device includes a housing, a needle connection part (55) for attaching a needle (61) to a cartridge (7) received in the housing (2), an injection drive mechanism (9), an electronic control system for controlling the injection drive mechanism (9), and a needle detection function for detecting the attachment of the needle (61) to the cartridge (7). The needle detection function (13) includes a slider (13) having a magnetic part and an electromagnetic sensor (203) disposed in the housing (2). The magnetic part is movable between a position away from the electromagnetic sensor (203) and a position near the electromagnetic sensor (203) when the slider (13) is in its retracted position. A signal indicating that the needle (61) is attached to the cartridge (7) is generated by the electromagnetic sensor (203).

Description

Technical Field

[0001] The present invention relates to an infusion device, and more particularly to an electromechanical infusion device for infusing a drug from a replaceable cartridge received in the device. Such an infusion device is typically controlled by an electronic control system. Similarly, in such an infusion device, it is necessary to attach a needle to the cartridge before use and remove and dispose of the needle after use.

[0002] More particularly, the present invention relates to an infusion device having a needle detection function for detecting the attachment of a needle to a cartridge and passing corresponding information to an electronic control system.

[0003] In a second aspect, the present invention relates to an infusion device comprising a needle shielding element mounted coaxially in a housing for shielding a needle attached to a cartridge.

[0004] In a third aspect, the present invention relates to an infusion device having a position detection function for detecting a situation where the device is pressed against an infusion surface.

Background Art

[0005] In this type of electronically controlled infusion device, it is desirable to prevent the device from performing an operation for infusing a drug to a user unless a condition that a needle is correctly attached to a cartridge is satisfied. Therefore, it is desirable that the device has means for detecting the presence of the needle and its correct attachment to the cartridge.

[0006] Systems for detecting the presence of a needle are known in the art. For example, in WO2005 / 077441, the detection system uses an optical sensor located in the cartridge / needle boundary region.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The use of such optical detection means has several drawbacks, particularly suggesting that the detection means cannot usually be combined with other electronic components, such as the positions of the optical transmitter and the optical receiver. In addition, the optical detection means may be exposed to various disturbances that can affect the reliability of detection.

Means for Solving the Problems

[0008] Therefore, an object of the present invention is to provide a detection function based on alternative technology that is not overly complicated to implement in an injection device and has high robustness.

[0009] Another object of the present invention is to provide a needle shielding function that can be conveniently handled to facilitate the attachment operation of the needle to the cartridge.

[0010] Yet another object of the present invention is to provide a position detection function related to simple and reliable means that is easy to implement in the device.

[0011] According to the present invention, there is provided an injection device, a long housing configured to extend along a longitudinal axis and receive a drug cartridge, a needle connection portion connected to a needle assembly having a needle and a needle hub for attaching the needle to the cartridge, an injection drive mechanism for driving a piston within the cartridge to discharge a drug from the cartridge, an electronic control system for controlling the injection drive mechanism based on user input and information indicating the state of the device, and a needle detection function for detecting the attachment of the needle to the cartridge and passing corresponding information to the electronic control system, wherein the needle detection function is a slider axially movable relative to the housing between an extended position and a retracted position, the slider comprising a magnetic portion, being biased to its extended position and maintained in its retracted position when the needle is attached to the cartridge, An electromagnetic sensor fixedly arranged within the housing, wherein the magnetic part is movable together with the slider between a position away from the electromagnetic sensor and a position near the electromagnetic sensor when the slider is in its retracted position, and a signal indicating that a needle is attached to the cartridge is generated by the electromagnetic sensor and passed to the electronic control system. An injection device is provided that has an electromagnetic sensor.

[0012] A preferred embodiment may have one or some of the following functions. The electronic control system is adapted not to operate the injection drive mechanism to release the drug from the cartridge if a signal indicating that the needle is attached to the cartridge is not passed by the electromagnetic sensor. The injection drive mechanism includes an axially displaceable piston rod for driving a piston within the cartridge and an electric motor for displacing the piston rod, and the electric motor is controlled by the electronic control system. The injection device further includes a body arranged within and fixedly attached to the housing, and the injection drive mechanism is attached to the body. The electronic control system has a processor and a printed circuit board fixedly arranged within the housing, and the electromagnetic sensor is supported by the printed circuit board and connected to the processor to pass a signal indicating that the needle is attached to the cartridge to the processor. The injection device further includes a cartridge holder for receiving and holding the cartridge, and the cartridge holder is relatively movable with respect to the housing between an open position where the cartridge can be installed in or removed from the cartridge holder and a closed position where the cartridge is in a position suitable for injection. The cartridge holder is rotatable between the open position and the closed position. The body and the cartridge holder include a fitting pivot pin and a pivot bearing that constitute a hinge connection, whereby the cartridge holder is rotatable relative to the housing between the open position and the closed position. The needle connection part includes a threaded cylindrical part of the cartridge holder provided at its distal end for screw connection of the needle hub. The slider includes a base for engaging with the needle assembly. The base has a central hole, and the central hole is designed such that when connecting the needle assembly to the needle connection part, the needle hub engages with the base at the peripheral edge of the hole while the needle passes through the hole. The base of the slider has a cup shape with a bottom wall facing the proximal side where the hole is provided. The bottom wall is substantially flat. Thus, when the needle hub is screwed and connected to the threaded part of the cartridge holder, and thereby the needle is attached to the cartridge, the bottom wall is firmly maintained at the retracted position of the slider between the needle hub and the cartridge holder, thereby constituting a partial seal to prevent any released drug from entering the housing from the cartridge. The slider includes an axial arm that protrudes proximally from the base and is provided with the magnetic part. The slider includes a guiding element that protrudes proximally from the base to axially guide the slider when the slider moves between the extended position and the retracted position. The body includes complementary guiding elements that engage with each guiding element of the slider to axially guide the slider when the slider moves between the extended position and the retracted position. The slider includes a biasing spring operably associated with each guiding element to bias the slider to its extended position.

[0013] According to another aspect of the present invention, there is provided an injection device, a long housing extending along a longitudinal axis and configured to receive a drug cartridge, An injection drive mechanism for driving a piston within the cartridge and thereby discharging a medicament from the cartridge, A needle shielding element which is nested within the housing and is adapted to shield a needle mounted to the cartridge and protruding distally from the housing in a fully extended position, and a fully retracted position spaced proximally from the extended position corresponding to a situation where the device is pressed against an injection site for injecting the medicament, and is axially displaceable between the fully extended position and the fully retracted position, A locking mechanism operable by a user to releasably lock the needle shielding element at one partial retracted position spaced proximally from the fully extended position and distally from the fully retracted position, the locking mechanism being suitable for facilitating attachment of the needle to the cartridge, The locking mechanism includes a locking button operable by a user to displace between a release position and a lock position, a first locking member attached to the locking button, and a corresponding second locking member provided on the needle shielding element, and a sliding path of the second locking member is defined by the displacement of the needle shielding element, The locking mechanism is designed such that when the locking button is in the release position, it is disengaged from the sliding path of the second locking member, and when the locking button is in the lock position, it is within the sliding path. Also, in the lock position, the first and second locking members are engaged to prevent distal displacement of the needle shielding element from the partial retracted position but allow proximal displacement of the needle shielding element. An injection device is provided.

[0014] Preferred embodiments may have one or some of the following functions. The locking button protrudes outwardly from the housing and is laterally displaceable between the release position and the lock position, One of the first and second locking members has a rigid stop member formed with a lateral contact surface and an inclined slope, and the other of the first and second locking members has a flexible arm. The flexible arm, at the locked position, engages with the slope and deflects and spreads to enable proximal displacement of the needle shielding element, and is also suitable for engaging with the contact surface to prevent distal displacement of the needle shielding element from the partially retracted position. The flexible arm is attached to the locking button, and the rigid stop member is provided on the needle shielding element. The flexible arm is a metal blade extending axially and attached to the locking button at one end, and the other end of the blade is a free end having an edge that engages with the lateral contact surface at the locked position. The injection device further comprises biasing means for biasing the needle shielding element to its fully extended position. The needle shielding element comprises a substantially cylindrical wall suitable for shielding a needle attached to the drug cartridge at the fully extended position, and an axial arm protruding proximally from the cylindrical wall and comprising the second locking member. The needle shielding element further comprises a guiding element protruding proximally from the cylindrical wall for guiding the needle shielding element axially when the needle shielding element moves between the fully extended position and the fully retracted position. The needle shielding element further comprises an enlarged gripping portion extending radially beyond the cylindrical wall at the distal end of the cylindrical wall. The enlarged portion engages with the distal edge of the housing at the fully retracted position to prevent further retraction of the needle shielding element. The gripping portion has a ridged surface to enhance capture by the user. The needle shielding element further comprises an axially extending holding arm protruding proximally from the cylindrical wall and provided with a stop member. The stop member is suitable for engaging with a complementary stop member fixed to the housing at the fully extended position to limit distal displacement of the needle shielding element. The injection device further comprises An electronic control system for controlling the injection drive mechanism based on user input and information indicating the state of the device, and a position detection function for detecting the position of the needle shielding element and passing corresponding information to the electronic control system. The position detection function includes a magnetic part provided on the needle shielding element and at least a first electromagnetic sensor fixedly arranged in the housing. The magnetic part is movable together with the needle shielding element between a position away from the first electromagnetic sensor and a position near the first electromagnetic sensor when the needle shielding element is in its fully retracted position. A signal indicating that the injection device is pressed against the injection surface and ready for injection is generated by the first electromagnetic sensor and passed to the electronic control system. The needle shielding element further includes a detection arm extending axially and protruding proximally from the cylindrical wall and provided with the magnetic part. The device further includes a second electromagnetic sensor fixedly arranged in the housing and axially spaced in the distal direction from the first electromagnetic sensor by a distance corresponding to the movement of the needle shielding element between the fully retracted position and the one partially retracted position. When the magnetic part is near the second electromagnetic sensor, a signal indicating that the needle shielding element is in a position suitable for the user to attach a needle to the cartridge is generated by the second electromagnetic sensor and passed to the electronic control system. The device further includes a body arranged in and fixedly attached to the housing, and the injection drive mechanism is attached to the body. The body includes complementary guiding elements that engage with each guiding element of the needle shielding element to axially guide the needle shielding element when the needle shielding element moves between the fully extended position and the fully retracted position. The electronic control system has a processor and a printed circuit board fixedly arranged in the housing. The electromagnetic sensor is supported by the printed circuit board and connected to the processor so as to pass a signal indicating the position of the needle shielding element to the processor. The electronic control system is adapted such that the injection drive mechanism is not actuated to discharge the liquid agent from the cartridge unless a signal indicating that the injection device is pressed against the injection surface and injection preparation is complete is passed by the electromagnetic sensor. The injection drive mechanism includes an axially displaceable piston rod for driving a piston within the cartridge and an electric motor for displacing the piston rod, the electric motor being controlled by the electronic control system.

[0015] According to another aspect of the present invention, there is provided an injection device comprising: a long housing configured to extend along a longitudinal axis and receive a drug cartridge; an injection drive mechanism for driving a piston within the cartridge to thereby discharge a drug from the cartridge; a needle shielding element axially displaceable between a fully extended position in which the needle shielding element is nested within the housing and is suitable for shielding a needle attached to the cartridge protruding distally from the housing, and a fully retracted position spaced proximally from the extended position corresponding to a situation where the device is pressed against an injection site for injecting the drug; an electronic control system for controlling the injection drive mechanism based on user input and information indicating the state of the device; the injection device further having a position detection function for detecting the position of the needle shielding element and passing corresponding information to the electronic control system; the position detection function includes a magnetic portion provided on the needle shielding element and a first electromagnetic sensor fixedly disposed within the housing, the magnetic portion being movable with the needle shielding element between a position away from the first electromagnetic sensor and a position near the first electromagnetic sensor when the needle shielding element is in its fully retracted position, and the injection device is provided, wherein the first electromagnetic sensor generates a signal indicating that the injection device is pressed against the injection surface and injection preparation is complete and passes it to the electronic control system.

[0016] A preferred embodiment may have one or some of the following functions. The electronic control system is adapted such that the injection drive mechanism is not actuated to discharge the liquid agent from the cartridge unless a signal indicating that the injection device is pressed against the injection surface and injection preparation is complete is passed by the electromagnetic sensor. The injection drive mechanism includes an axially displaceable piston rod for driving a piston within the cartridge and an electric motor for displacing the piston rod, the electric motor being controlled by the electronic control system. The injection device further includes a body disposed within and fixedly attached to the housing, and the injection drive mechanism is attached to the body. The electronic control system has a processor and a printed circuit board fixedly disposed within the housing. The electromagnetic sensor is supported by the printed circuit board and is connected to the processor to pass a signal indicating the position of the needle shielding element to the processor. The injection device further includes biasing means for biasing the needle shielding element to its fully extended position. The needle shielding element includes a substantially cylindrical wall suitable for shielding the needle attached to the drug cartridge in the fully extended position and an axially extending detection arm protruding proximally from the cylindrical wall and having the magnetic portion. The needle shielding element further includes a guiding element protruding proximally from the cylindrical wall for guiding the needle shielding element axially when the needle shielding element moves between the fully extended position and the fully retracted position. The body includes complementary guiding elements that engage with each guiding element of the needle shielding element for guiding the needle shielding element axially when the needle shielding element moves between the fully extended position and the fully retracted position. The needle shielding element further comprises an enlarged gripping portion extending radially beyond the cylindrical wall at the distal end of the cylindrical wall, the enlarged portion engaging with the distal edge of the housing in the fully retracted position, thereby preventing further retraction of the needle shielding element. The gripping portion has a ribbed surface to enhance capture by the user. The needle shielding element further comprises an axially extending retaining arm protruding proximally from the cylindrical wall and provided with a stop member, the stop member being adapted to engage with a complementary stop member fixed to the housing in the fully extended position to limit displacement of the needle shielding element in the distal direction. The device further comprises a locking mechanism operable by the user to releasably lock the needle shielding element in one partial retracted position spaced proximally from the fully extended position and distally from the fully retracted position, the partial retracted position being suitable for facilitating attachment of the needle to the cartridge. The locking mechanism has a locking button operable by the user to displace between a release position and a lock position, a first locking member attached to the locking button, and a corresponding second locking member provided on the needle shielding element, the displacement of the needle shielding element defining a sliding path of the second locking member. The locking mechanism is configured such that when the locking button is in the release position, it is out of the sliding path of the second locking member, and when the locking button is in the lock position, it is within the sliding path. Also, in the lock position, the first and second locking members are engaged to prevent distal displacement of the needle shielding element from the partial retracted position but allow proximal displacement of the needle shielding element. The locking button protrudes outwardly from the housing and is laterally displaceable between the release position and the lock position. One of the first and second locking members has a rigid stop member formed with a lateral contact surface and an inclined slope, and the other of the first and second locking members has a flexible arm, and the flexible arm engages with the slope and deflects and spreads at the lock position to allow proximal displacement of the needle shielding element, and also engages with the contact surface and is suitable for preventing distal displacement of the needle shielding element from the partial retracted position. The flexible arm is attached to the locking button, and the rigid stop member is provided on the needle shielding element. The flexible arm is a metal blade extending axially and attached to the locking button at one end, and the other end of the blade is a free end having an edge that engages with the lateral contact surface at the lock position. The device further includes a second electromagnetic sensor fixedly disposed within the housing and axially spaced distally from the first electromagnetic sensor by a distance corresponding to movement of the needle shielding element between the fully retracted position and the one partial retracted position, and when the magnetic portion is near the second electromagnetic sensor, a signal indicating that the needle shielding element is in a position suitable for the user to attach a needle to the cartridge is generated by the second electromagnetic sensor and passed to the electronic control system. Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the following drawings.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9A

Figure 9A

Figure 9C

Figure 9D

Figure 10A

Figure 10B

Figure 10C

Figure 11

Figure 12A

Figure 12B

Figure 12C

DETAILED DESCRIPTION OF THE INVENTION

[0018] The following definitions are used in this specification and the claims. The term "distal" refers to a position or direction that is close to or towards the outlet for the contents of the drug cartridge when received in the injection device. The term "proximal" refers to a position or direction that is opposite to the distal position or direction, and / or a position or direction that is close to or towards the capture portion of the injection device.

[0019] The present invention will be further described below with reference to the following preferred embodiments shown in the drawings.

[0020] The injection device shown in each figure is an electromechanical device that is electronically controlled such that an injection force is applied by an electric motor, particularly controlled by an electronic control system. The device is reusable and is adapted to receive a replaceable drug cartridge containing the drug to be injected.

[0021] Referring to FIG. 1, FIG. 2A, and FIG. 2B, the injection device 1 includes an elongated housing 2 extending along the longitudinal axis X. The housing 2 is formed by two outer shells 2a and 2b. The outer shells 2a and 2b fit together to define an internal volume.

[0022] The injection device 1 further includes a body 3 disposed within the internal volume defined by the outer shells 2a and 2b and fixedly attached to the housing 2, a cartridge holder 5 (hereinafter also referred to as a door) for receiving and holding the drug cartridge 7, and an injection drive mechanism 9 for driving a piston within the cartridge 7 to thereby discharge the drug from the cartridge.

[0023] At the distal end, the device 1 has a needle shielding element 11 for shielding the needle attached to the cartridge 7, a slider 13 for detecting the presence of the needle, and an annular seal 15 attached to the housing 2 for making a sealed connection between the distal edge 17 of the housing 2 and the needle shielding element when the device 1 is pressed against the injection site.

[0024] The device 1 also has a screen 19 provided on the proximal surface of the housing 2 for displaying visual information to the user, for example regarding the state of the device, and menu buttons 20 adjacent to the screen 19 for selecting the information displayed on the screen 19. The device further has a switch button 21 provided on the side of the housing 2 for switching the device on / off, an injection button 22 for the user to activate the injection, and a speaker 23 located at the proximal end for delivering an audio signal to the user.

[0025] As can be seen in FIG. 2B, the device 1 includes a locking button 25 protruding from the housing 2. The locking button 25 is actuated by the user to displace laterally in order to selectively lock or release the needle shielding element 11, as will be further described below.

[0026] Referring particularly to FIGS. 1 and 3, the device 1 comprises an electronic control system. The electronic control system has a processor (not shown), a main printed circuit board (PCB) 31 fixedly disposed within the housing 2 in the proximal region to support the processor, and a second PCB 32 that supports the sensors described below. The electronic control system is particularly adapted to acquire information indicating the state of the device (e.g., the needle being attached, the device being pressed against the injection site, etc.) and user inputs (e.g., the control button 21 being pressed, etc.), and to control the injection drive mechanism based on such information and user inputs.

[0027] It can be seen that on the inner surface of the outer shell 2b, there are provided protrusions 33 for supporting and fixing the main PCB 31. Similarly, on the outer shell 2a, there is formed an axially elongated through-hole 35 designed to fit with the cartridge holder 5.

[0028] The body 3 is a rigid structural part designed to fixedly support the stationary part of the injection drive mechanism 9. The body also rotatably supports the cartridge holder 5, and is designed to guide the needle shielding element 11 and the slider 13, both mounted on the body 3, to slide axially with respect to the housing 2. For this purpose, the body 3 has, at its distal end, a pair of opposing pivot bearings 39 having a common transverse axis for rotatably supporting the cartridge holder 9, and two pairs of axially extending guide bolts 41. As the needle shielding element 11 and the slider 13 move relative to the housing 2 respectively, one pair of these guide bolts 41 is provided to axially guide the needle shielding element 11, and the other pair is provided to axially guide the slider 13. The body 3 defines a central cavity 43 substantially over its entire length. The central cavity 43 is axially elongated to accommodate the cartridge holder 5 in its closed position and the cartridge 7 inserted therein.

[0029] The device 1 is provided with means for maintaining the cartridge 7 received in the housing 2 in a fixed position, in particular an axial fixed position, with respect to the body 3. These means include a cartridge seal 45 (shown in Figure 3). The cartridge seal 45 is provided to engage in a sealed manner with the distal end of the cartridge so as to prevent any leakage of the drug into the device.

[0030] The cartridge holder 5 is formed as an elongate sleeve suitable for axially receiving the drug cartridge 7 and comprises an upper wall 47, a bottom wall 48 and opposing side walls 49. The side walls 49 are provided with respective pivot pins 51 which extend transversely and are coaxial, and these pivot pins 51 engage with respective pivot bearings 39 of the body to form a hinge connection. By the cartridge holder 5 being articulated to the body 3 in this rotatable manner, the cartridge holder 5 is rotatable with respect to the housing 2 between an open (Figure 8) and a closed (Figure 2A) position. In the open position, the cartridge 7 can be installed into or removed from the cartridge holder 5. In the closed position, the cartridge 7 received in the cartridge holder 5 is in a position suitable for injection. The cartridge holder 5 has a shape and dimensions such that it passes through the elongate through-hole 35 of the outer contour 2a. In particular, the upper wall 47 has a shape such that it engages with the elongate through-hole 35 of the outer contour 2a and closes the whole when the cartridge holder 5 is in the closed position.

[0031] The cartridge holder 5 is provided with a window 53 on its upper wall 47 so that the contents of the cartridge 7 can be visually confirmed. Similarly, the cartridge holder 5 is formed at its distal end with a needle connection portion 55 for connection to the needle assembly 60 (Figure 10A) and attachment of the needle 61 (Figure 10A) to the drug cartridge 7. The needle connection portion 55 is constituted by a threaded portion of a cylindrical sleeve protruding distally, provided to accommodate the distal end of the drug cartridge 7.

[0032] The cartridge holder 5 is provided with a door magnet (not shown) attached to the bottom wall 48 for detecting the closed position of the cartridge holder 5 by a door sensor disposed within the housing 2. A long through-hole is also formed in the bottom wall 48. A flexible detection arm attached to the body 3 for detecting the presence of a cartridge by a cartridge sensor disposed within the housing 2 engages with this long through-hole.

[0033] A mechanism for locking the cartridge holder 5 in the closed position and opening the cartridge holder is omitted in this disclosure.

[0034] In the illustrated embodiment, the cartridge 7 is of a multi-chamber type and has a cylindrical body portion 62 and a neck portion 63 at its distal end. The cartridge 7 further has two pistons 65 and 66 slidably disposed within the cylindrical body portion 62. In the initial state of the cartridge 7, as shown in FIG. 3, the first piston 65 is provided at the proximal end of the body portion 62 so as to seal the proximal end of the cartridge 7, and the second piston 66 is disposed distally and axially spaced apart from the first piston. Thereby, both pistons 65 and 66 typically define two compartments or chambers 67 and 68 that contain a product to be mixed, typically prior to injection. Specifically, the first chamber 67 typically contains a liquid agent (or solvent), and the second chamber 68, which is located distally with respect to the first chamber, contains a lyophilized drug. A bypass portion 69 is formed in the body portion 62 so that the liquid agent can flow through the second chamber 68 and be mixed with the lyophilized drug. A distal opening is formed in the neck portion 63, and a partition wall 71 that closes the distal opening and through which a hollow needle can penetrate is provided. When the cartridge 7 is received in the cartridge holder 5, the neck portion 63 is engaged within the cylindrical sleeve of the cartridge holder that projects distally where the needle connection portion 55 is formed.

[0035] As can be seen in FIG. 10A, the needle assembly 60 is in fluid communication with the chamber 68 and has a needle 60 and a needle hub 73. The needle hub 73 supports the needle and is provided with an internal thread. This internal thread mates with the needle connection portion 55 of the cartridge holder 5 for attaching the needle 61 to the cartridge. The needle assembly 60 further includes a detachable needle cap 75 for protecting the intermediate needle 61 while the needle is being attached to the cartridge 7. Once the needle 61 is attached to the cartridge 7, the needle cap 75 can be removed.

[0036] Although the illustrated embodiment includes a multi-chamber cartridge, it will be understood that the present invention is applicable to any type of cartridge, and in particular to a cartridge having a single chamber for containing a liquid product.

[0037] Continuing to refer to FIGS. 1 and 3, the injection drive mechanism 9 includes an axially and axially displaceable piston rod 81 for driving the pistons 65, 66 within the cartridge 7, and an electric motor 83 provided with an output shaft 84 for displacing the piston rod 81 and controlled by an electronic control system. The device 1 includes a battery (not shown) for supplying power to the motor 83. The injection drive mechanism 9 further includes a transmission 85 for transmitting and converting the movement of the output shaft 84 to cause a linear displacement of the piston rod 81.

[0038] The injection drive mechanism 9 is attached to the body 3 such that the stationary part of the injection drive mechanism 9 having the motor 83 and the transmission 85 is firmly attached to the body, and the piston rod 81 is axially displaceable relative to these stationary parts and the body 3.

[0039] When the needle is attached to the cartridge 7 and when the device is activated, in the injection mode, the injection drive mechanism 9 drives the pistons 65, 66 within the cartridge by means of the piston rod 81. In a multi-chamber configuration as illustrated, for example, with the present embodiment, this may mix the liquid agent with the lyophilized agent and / or discharge the agent from the cartridge through the needle 61. Alternatively, in the case of a single-chamber configuration, when the piston is driven within the cartridge, the liquid agent will be discharged from the cartridge through the needle.

[0040] Referring particularly to FIGS. 1, 3, 4A, and 4B, the needle shielding element 11 is mounted on the housing 2 in a nested fashion and is axially displaceable between the fully extended position (shown in FIG. 3) and the fully retracted position (FIG. 12A). In the fully extended position, the needle shielding element 11 projects distally from the housing 2 and is suitable for shielding the needle 61 attached to the cartridge 7. The fully retracted position of the needle shielding element 11 is spaced proximally from the extended position and corresponds to the situation where the device 1 is pressed against the injection site for injecting the agent.

[0041] The needle shielding element 11 includes a substantially cylindrical wall 91 that, in the fully extended position, is suitable for shielding the needle 61 attached to the drug cartridge 7.

[0042] The needle shielding element 11 further includes a pair of guide elements 93 formed as hollow cylinders projecting proximally from the cylindrical wall 91. The pair of hollow cylinders 93 are slidably engaged with corresponding pairs of each guide bolt 41 that are provided on the body 3 and that constitute complementary guide elements for axially guiding the needle shielding element 11 when it moves between the fully extended position and the fully retracted position. The needle shielding element 11 further includes biasing means in the form of a pair of compression springs 95 respectively disposed in each hollow cylinder 93 for biasing the needle shielding element 11 to its fully extended position.

[0043] The needle shielding element 11 further includes a holding arm 97 extending in the axial direction. The holding arm 97 projects proximally from the cylindrical wall 91 and is provided with a stop member 99. The stop member 99 is suitable for engaging with a complementary stop member (not shown) of the body 3 at the fully extended position to limit the distal displacement of the needle shielding element 11. In other forms, the complementary stop member may be fixed to the housing 2 or may be integral with the housing 2.

[0044] The needle shielding element 11 further includes an enlarged gripping portion 101 extending radially beyond the cylindrical wall 91 at the distal end of the cylindrical wall 91. The enlarged gripping portion 101 may be formed of a relatively soft material compared to the material of the cylindrical wall 91 and other parts of the needle shielding element. The enlarged gripping portion 10 may be overmolded on the cylindrical wall 91 or may be attached to the cylindrical wall 91. The gripping portion 101 has a ridged surface 103 to enhance capture by the user. The enlarged gripping portion is designed to engage with the distal edge 17 of the housing at the fully retracted position of the needle shielding element 11 to prevent further retraction. In this fully retracted position, the gripping portion 101 engages the distal edge 17 of the housing 2 in the sense of being pressed against it, but does not contact the distal edge 17 directly because the annular seal 15 is interposed between the distal edge 17 and the gripping portion 101.

[0045] The needle shielding element 11 further includes a locking arm 105 projecting proximally from the cylindrical wall 91 and extending in the axial direction. The locking arm 105 is provided with a notch 107 opening laterally, a rigid stop member 108 having a lateral abutment surface 109, and an inclined slope 110. The needle shielding element 11 also has a detection arm 115 formed as an axially extended portion of the locking arm 105, and a magnetic part such as a magnet 117 is attached to the detection arm 115.

[0046] Referring particularly to FIGS. 1, 3, and 5, the slider 13 is nested in the housing 2 and is axially movable between the extended position shown in FIG. 3 and the retracted position (FIG. 10A).

[0047] The slider 13 includes a base 131 for engaging with the needle assembly 60 (FIG. 10A). The base has a central hole 132. The central hole 132 is designed such that when the needle assembly 60 is connected to the needle connection part 55, the needle hub 73 can engage with the base at the peripheral edge 133 of the hole while the needle 61 passes through the hole. The base 131 of the slider 13 is cup-shaped with a bottom wall 135. The bottom wall 135 has the hole 132 and faces proximally. Since the bottom wall 135 is substantially planar, when the needle hub 73 is screwed and connected to the needle connection part 55, that is, the threaded part of the cartridge holder 5, and thereby the needle 61 is attached to the cartridge 7, the bottom wall 135 is firmly maintained between the needle hub 73 and the cartridge holder 5. In this configuration, the slider 13 is maintained in the retracted position to form a partial seal that prevents any released drug from entering from the cartridge 7 into the housing 2.

[0048] Similar to the needle shielding element 11, the slider 13 includes a pair of guide elements formed as hollow cylinders 137 protruding proximally from the base 131. The pair of hollow cylinders 137 are provided on the body 3 and slidably engage with corresponding pairs of each guide bolt 41 that constitute complementary guide elements for axially guiding the slider 13 when it moves between the extended position and the retracted position. The slider 13 further includes biasing means in the form of a pair of compression springs 139 respectively disposed in and operably associated with each hollow cylinder 137 to bias the slider to its extended position.

[0049] The slider is provided with an axial arm 140. The axial arm 140 protrudes proximally from the base 131 and is provided with a magnetic part such as a slider magnet (not shown) inserted and fixed in a cavity 141 located at the free end of the axial arm 140, for example. The slider 13 is also provided with a pair of axially extending holding arms 143. The holding arms 143 protrude proximally from the base 131 and are provided with a stop member 145. The stop member 145 is suitable for engaging with a complementary stop member (not shown) of the body 3 in the extended position to limit the displacement of the slider 13 in the distal direction.

[0050] It should be noted that the needle shielding element 11 and the slider 13 are each slidable independently with respect to the housing 2 between their respective extended positions and retracted positions.

[0051] In particular, referring to FIGS. 6, 7, and 10B, it can be seen that the injection device 1 has a locking mechanism. The locking mechanism is operable by the user to releasably lock the needle shielding element 11 at one partial retracted position (FIGS. 10A and 10B) spaced proximally from the fully extended position (FIGS. 3 and 6) and spaced distally from the fully retracted position (FIGS. 7 and 12C). The partial retracted position is suitable for facilitating the attachment of the needle 61 to the cartridge 7.

[0052] In the configurations of FIGS. 6, 7, and 10B, the needle shielding element 11 is in its fully extended position, its fully retracted position, and its partially retracted locked position, respectively.

[0053] The locking mechanism has a locking button 25 operable by the user to be displaced laterally between an unlocked position and a locked position, a first locking member attached to the locking button 25, and a corresponding second locking member provided on the needle shielding element 11.

[0054] In the illustrated embodiment, the first locking member is a flexible arm in the form of a metal blade 151 that extends axially and is attached at one end to the locking button 25. The other end of the blade is a free end having an edge 153 for engaging with the second locking member.

[0055] The second locking member includes a rigid stop member 108 formed with a lateral abutment surface 109 and an inclined ramp 110 by the locking arm 105. In the locked position of the locking member, the edge 153 of the blade 151 engages with the lateral abutment surface 109.

[0056] The displacement of the needle shielding element 11 defines the sliding path of the locking arm 105, and it will be understood that the locking mechanism is designed such that the blade 151 is out of the sliding path of the locking arm 105 when the locking button 25 is in the release position, as shown in FIG. 6 (also shown in FIG. 12C). When the locking button 25 is in the locked position, the blade 151 is within the sliding path of the locking arm 105.

[0057] The blade 151 also engages with and slides on the ramp 110 and flexes and spreads when the needle shielding element 11 moves proximally from its fully extended position in the locked position of the locking button 25, being suitable to allow such proximal displacement of the needle shielding element. When reaching the notch 107, the blade 151 flexes back and drops into the notch 107. When the needle shielding element 11 attempts to return distally from its axial position towards its extended position, the edge 153 engages with the abutment surface 109, thereby preventing the distal displacement of the needle shielding element 11 from its partially retracted position. However, from this axial position, the locking mechanism allows the needle shielding element 11 to displace further proximally to the fully extended position (FIG. 7).

[0058] In another embodiment (not shown), the flexible arm or blade 151 may be provided on the needle shielding element 11, and the rigid stop member 108 may be provided on the locking button 25.

[0059] As shown in FIGS. 6, 7, 10B, and 12C, the injection device 1 is provided with a position detection function for detecting the position of the needle shielding element 11 and passing the corresponding information to the electronic control system.

[0060] The position detection function has a magnet 117 provided on the detection arm 115 of the needle shielding element 11. Further, it has a first electromagnetic sensor 201 and a second electromagnetic sensor 202 that are supported by the PCB 32 and thereby fixedly arranged in the housing 2. The second electromagnetic sensor 202 is axially spaced from the first electromagnetic sensor 201 in the distal direction by a distance corresponding to the movement of the needle shielding element 11 between the fully retracted position (FIG. 7) and the partially retracted position (FIG. 10B). The electromagnetic sensors 201 and 202 are connected to the processor so as to pass a signal indicating the position of the needle shielding element 11 to the processor.

[0061] Together with the needle shielding element 11, the magnet 117 is axially movable between a position far from the first sensor 201 and the second sensor 202 (FIG. 6), a position far from the first sensor 201 and close to the second sensor 202 (FIG. 10B), and a position close to the first electromagnetic sensor 201 and far from the second sensor 202.

[0062] When at a position far from one of the electromagnetic sensors 201 and 202, the magnetic field of the magnet 117 cannot change the state of the sensor 210 or 202. When at a position close to (or in the vicinity of) one of the electromagnetic sensors 201 and 202, the magnetic field of the magnet 117 can change the state of the sensor 201 or 202.

[0063] The position of the magnet 117 close to the first sensor 201 corresponds to the form in which the needle shielding element 11 is in its fully retracted position. At this position, the first sensor 201 creates a signal indicating that the injection device 1 is pressed against the injection surface and ready for injection, and passes it to the electronic control system.

[0064] The position of magnet 117 close to the second sensor 202 corresponds to the configuration in which the needle shielding element 11 is in its partial retracted position. In this position (when maintained by the locking mechanism), the second sensor 202 creates and passes to the electronic control system a signal indicating that the needle shielding element 11 is in a position suitable for the user to attach the needle to the cartridge.

[0065] The electronic control system is adapted such that it does not activate the injection drive mechanism 9 to discharge the medicament from the cartridge unless a signal indicating that the injection device 1 is pressed against the injection surface and is ready for injection is passed by the first electromagnetic sensor 201.

[0066] As shown in FIGS. 6, 9C and 10C, the injection device further has a needle detection function for detecting that the needle 61 is attached to the cartridge 7 and passing the corresponding information to the electronic control system.

[0067] The needle detection function has a slider magnet provided on the axial arm 140 of the slider 13 and a third electromagnetic sensor 203 supported by the PCB 32 and fixedly arranged in the housing thereby. The electromagnetic sensor 203 is connected to the processor so as to pass to the processor a signal indicating that the needle is attached to the cartridge.

[0068] Together with the slider 13, the slider magnet provided in the cavity 141 is axially movable between a position away from the sensor 203 (FIG. 9C) and a position close to the sensor 203 (FIG. 10C). When in a position far from the electromagnetic sensor 203, the magnetic field of the slider magnet cannot change the state of the sensor 203. When in a position close to (or in the vicinity of) the electromagnetic sensor 203, the magnetic field of the slider magnet can change the state of the sensor 203.

[0069] As shown in FIG. 9C, the position of the slider magnet away from the sensor 203 corresponds to the form in which the slider 13 is in its extended position. As shown in FIG. 10C, the position of the slider magnet close to the sensor 203 corresponds to the form in which the slider 13 is in its retracted position. In order to maintain the slider 13 in the retracted position, it is necessary to attach the needle 61 to the cartridge 7. At this position, the sensor 203 creates a signal indicating that the needle is attached to the cartridge and passes it to the electronic control system.

[0070] The electronic control system is adapted such that it does not activate the injection drive mechanism 9 to discharge the liquid agent from the cartridge unless a signal indicating that the needle is attached to the cartridge is passed by the electromagnetic sensor 203.

[0071] Referring now more specifically to FIGS. 6 and 7, it can be seen that the injection device 1 further has a fourth electromagnetic sensor 204 and a fifth electromagnetic sensor 205 that are fixed and supported by the PCB 32 and connected to the processor.

[0072] Similar to the electromagnetic sensors 201, 202, and 203 described above, the sensors 204 and 205 can detect the proximity of each magnet and pass their respective signals to the processor.

[0073] The fourth sensor (or door sensor) 204 is associated with a door magnet provided on the bottom wall 48 and detects the closed position of the cartridge holder 5. At the closed position, the sensor 204 generates a signal indicating that the cartridge holder (door) is closed on the housing 2 and passes it to the electronic control system.

[0074] The fifth sensor (or cartridge detection sensor) 205 is associated with a cartridge detection magnet (not shown) that detects the presence of the cartridge 7 within the cartridge holder 5. As already explained above and as shown in FIG. 7, the apparatus 1 includes a flexible detection arm 207 attached to the body 3. The detection arm 207 has an elbow 208 and a free end 209 provided with the cartridge detection magnet. The elbow 208 projects into the cartridge holder 5 through the elongated hole in the bottom wall 48 when the cartridge holder 5 is in the closed position. When the cartridge 7 is not within the cartridge holder 5, the detection arm 207 remains in its released state with the cartridge detection magnet spaced from the sensor 205, while when the cartridge is in the cartridge holder 5, the elbow 208 is pushed out to flex the detection arm 207 and bring the free end 209 closer to the sensor 205.

[0075] In the latter configuration, the cartridge 7 is within the cartridge holder 5 and the cartridge holder 5 is closed on the housing 2, while the sensor 205 generates a signal indicating that the door is closed and the cartridge is in place within the housing 2 and passes it to the electronic control system.

[0076] Starting from the initial configuration of the injection device as shown in FIGS. 2A and 2B, the main steps of operating the device will be described below with reference to FIGS. 8 - 12.

[0077] The user who wishes to proceed with the injection must ensure that the drug cartridge 7 is securely within the cartridge holder 5. This information can be automatically acquired by the device and displayed on the screen 19. If it is necessary to fill the device with an unused cartridge, as illustrated in FIG. 8, the user must open the cartridge holder 5 and axially insert the cartridge into the cartridge holder 5. This can be similarly illustrated in the same FIG. 8 for the reverse operation of removing an empty cartridge from the device, especially for replacement.

[0078] The following describes a series of operations for locking the needle shielding mechanism 11 and attaching a needle to the cartridge with reference to FIGS. 9A, 9B, 9C, 9D, 10A, and 10B.

[0079] The user needs to manually retract the needle shielding element 11 from the extended position and lock it at a partially retracted position (FIGS. 9A, 9B, 9D) suitable for installing the needle assembly. To do this, the user needs to move the locking button 25 laterally to the positions shown in FIGS. 9B and 9D. As described above, the user may place the button 25 in the locked position before or after retracting the needle shielding element 11. If the button 25 is in the locked position before retraction, the flexible blade slides on the inclined surface 110 during retraction, and each locking member can reach these engagement positions, so that the needle shielding element 11 can be retracted. Since the needle shielding element 11 and the slider can move independently, the slider 13 remains in its extended position.

[0080] In particular, as shown in FIG. 9C, the slider magnet remains axially spaced from the sensor 203.

[0081] FIG. 10A illustrates the process of attaching the needle 61 to the cartridge 7. To perform this, the user needs to insert the needle assembly 60 into the distal end of the device, thereby pushing the slider 13 back in the proximal direction. The attachment is achieved by threadedly engaging the needle hub 73 with the needle connection portion 55 of the cartridge holder 5. When performing this, the needle 61 penetrates the partition wall 71. Thereafter, the user may remove the needle cap 75, thereby exposing the needle.

[0082] In this position, as shown in FIG. 10B, the magnet 117 of the needle shielding element 11 is close to the sensor 202, thereby indicating to the electronic control system that the needle shielding element 11 is in a locked position suitable for attaching the needle.

[0083] When the slider 13 is maintained in the retracted position by the needle hub 73, as shown in FIG. 10C, the slider magnet stays close to the sensor 203, indicating the presence of the needle 61 attached to the cartridge.

[0084] When attaching the needle 61 to the cartridge, the user may return the locking button 25 to the release position (FIG. 11B) to release the locking mechanism and allow the needle shielding element 11 to return to its initial extended position (FIGS. 11A and 11B) under the biasing effect of the spring 95. In this position, the cylindrical wall 91 of the needle shielding element surrounds the needle 61, thus helping to shield the needle and reduce the anxiety associated with injection. The device is then ready for injection.

[0085] At this position, as shown in FIG. 6, it will be understood that the magnet 117 of the needle shielding element 11 is away from the sensors 201 and 202.

[0086] FIGS. 12A, 12B, and 12C illustrate the injection device 1 in the injection configuration. Here, the user presses the injection device against the injection site in view of starting the injection of the drug from the cartridge by pressing the injection button 22.

[0087] As can be seen in these figures, the needle shielding element 11 moves to its fully retracted position against the biasing force of the spring 95, and the gripping portion 101 hits the annular seal 15 (not shown in FIG. 12C) and is stopped by the distal edge 17 of the housing. The slider 13 remains in the retracted position as it is.

[0088] At this position, as shown in FIG. 12C, the magnet 17 of the needle shielding element 11 is close to the first sensor 201, thereby indicating to the electronic control system that the needle shielding element 11 is in the fully extended position and is in a suitable position for performing the injection.

[0089] It will be understood that the electronic control system is configured to control the injection drive mechanism to release the drug from the cartridge in a plurality of cumulative situations that may include one or more of the following. The cartridge holder is closed. There is a cartridge inside the cartridge holder. The needle is properly attached to the cartridge. The needle shielding element is fully retracted.

Claims

1. 1. An injection device comprising: an elongate housing (2) extending along a longitudinal axis (X) and configured to receive a medication cartridge (7); a needle coupling (55) for coupling with a needle assembly (60) having a needle (61) and a needle hub (73) to thereby attach said needle to said cartridge; an injection drive mechanism (9) for driving pistons (65, 66) within the cartridge, thereby expelling the medicament from the cartridge (7); an electronic control system for controlling the injection drive mechanism (9) based on user input and information indicative of the status of the device (1); a needle detection function for detecting attachment of a needle (61) to the cartridge (7) and passing corresponding information to the electronic control system; The needle detection function a slider (13) axially movable relative to the housing between an extended position and a retracted position, the slider (13) comprising a magnetic portion, biased to its extended position and maintained in its retracted position when a needle (61) is attached to the cartridge (7); an electromagnetic sensor (203) fixedly arranged within the housing (2), the magnetic portion being movable together with the slider (13) between a position spaced apart from the electromagnetic sensor (203) and a position adjacent to the electromagnetic sensor when the slider (13) is in its retracted position, the electromagnetic sensor (203) generating a signal indicating that a needle (61) has been attached to the cartridge (7) and passing it to the electronic control system.

2. 2. An injection device according to claim 1, wherein the electronic control system is adapted not to activate the injection drive mechanism (9) to expel the medicament from the cartridge (7) unless a signal is passed by the electromagnetic sensor (203) indicating that a needle (61) has been attached to the cartridge (7).

3. 2. The injection device according to claim 1, wherein the injection drive mechanism (9) comprises an axially displaceable piston rod (81) for driving pistons (65, 66) in the cartridge (7) and an electric motor (83) for displacing the piston rod (81), the electric motor (83) being controlled by the electronic control system.

4. 2. The injection device of claim 1, further comprising a body (3) disposed within and fixedly attached to the housing (2), the injection drive mechanism (9) being attached to the body (3).

5. 5. An injection device according to claim 4, wherein the electronic control system comprises a processor and a printed circuit board (32) fixedly arranged within the housing (2), and the electromagnetic sensor (203) is supported by the printed circuit board (32) and is connected to the processor so as to pass a signal to the processor indicating that a needle (61) has been attached to the cartridge (7).

6. 2. An injection device as described in claim 1, further comprising a cartridge holder (5) for receiving and holding the cartridge (7), the cartridge holder (5) being movable relative to the housing (2) between an open position in which the cartridge (7) can be installed in or removed from the cartridge holder (5), and a closed position in which the cartridge (7) is in a position suitable for injection.

7. 7. An injection device according to claim 6, wherein the cartridge holder (5) is rotatable between the open and closed positions.

8. 8. An injection device according to claim 7, comprising a body (3) disposed within and fixedly attached to the housing (2), the injection drive mechanism (9) being attached to the body (3), and the body (3) and the cartridge holder (5) comprising a mating pivot pin (51) and pivot bearing (39) forming a hinged connection, whereby the cartridge holder (5) is rotatable relative to the housing (2) between the open position and the closed position.

9. 7. An injection device according to claim 6, wherein the needle connection (55) comprises a threaded tubular portion of the cartridge holder (5) provided at its distal end for threaded connection with the needle hub (73).

10. 10. An injection device according to any one of claims 1 to 9, wherein the slider (13) comprises a base (131) for engaging with the needle assembly (60), the base (131) having a central hole (132), the central hole (132) being designed so that when the needle assembly (60) is connected to the needle connecting part (55), the needle (61) passes through the hole (132) while the needle hub (73) engages with the base (131) at a peripheral edge (133) of the hole (132).

11. 11. The injection device according to claim 10, wherein the base (131) of the slider (13) is cup-shaped with a bottom wall facing proximally and having the hole (132), and the bottom wall is substantially flat, so that when the needle hub (73) is threadably connected to the threaded portion of the cartridge holder (5) thereby attaching a needle (61) to the cartridge (7), the bottom wall firmly maintains the slider (13) in the retracted position between the needle hub (73) and the cartridge holder (5), thereby forming a partial seal that prevents any released medicament from entering the housing (2) from the cartridge (7).

12. 11. The injection device of claim 10, wherein the slider (13) comprises an axial arm (140) protruding proximally from the base (131) and provided with the magnetic portion.

13. 11. An injection device according to claim 10, wherein the slider (13) comprises a guide element (137) protruding proximally from the base (131) for axially guiding the slider (13) as it moves between the extended position and the retracted position.

14. 14. An injection device according to claim 13, which relies on claim 4, wherein the body (3) comprises complementary guide elements (41) which engage with each guide element (137) of the slider (13) to axially guide the slider (13) as it moves between the extended position and the retracted position.

15. 14. The injection device of claim 13, wherein the slider (13) comprises a biasing spring operatively associated with each guide element (137) for biasing the slider (13) to its extended position.

16. 1. An injection device comprising: an elongate housing (2) extending along a longitudinal axis (X) and configured to receive a medication cartridge (7); an injection drive mechanism (9) for driving pistons (65, 66) within said cartridge (7) and thereby expelling the medicament from said cartridge (7); a needle shielding element (11) telescopically mounted in the housing (2) and axially displaceable between a fully extended position in which the needle shielding element (11) protrudes distally from the housing (2) and is suitable for shielding a needle (61) attached to the cartridge (7), and a fully retracted position spaced proximally from the extended position corresponding to a situation in which the device is pressed against an injection site to inject the medicament; a locking mechanism operable by a user to releasably lock the needle shield element (11) at a partially retracted position spaced proximally from the fully extended position and spaced distally from the fully retracted position, the locking mechanism adapted to facilitate attachment of a needle (61) to the cartridge (7); the locking mechanism comprises a locking button (25) actuated by a user to be displaced between an unlocked position and a locked position, a first locking member (151) attached to the locking button (25), and a corresponding second locking member (105) provided on the needle shield element (11), wherein the displacement of the needle shield element (11) defines a sliding path for the second locking member (105); The locking mechanism is designed so that the locking button (25) is disengaged from the sliding path of the second locking member (105) when the locking button (25) is in the released position and is in the sliding path when the locking button (25) is in the locked position, and so that in the locked position the first and second locking members (151 and 105) engage to prevent distal displacement of the needle shield element (11) from the partially retracted position but allow proximal displacement of the needle shield element (11).

17. 17. An injection device according to claim 16, wherein the locking button (25) projects outwardly from the housing (2) and is laterally displaceable between the release position and the lock position.

18. 17. The injection device of claim 16, wherein one of the first and second locking members (151 and 105) comprises a rigid stop member having a lateral abutment surface (109) and an inclined ramp (110), and the other of the first and second locking members comprises a flexible arm (151) which, in the locked position, is adapted to engage with the ramp and flex and expand to allow proximal displacement of the needle shield element (11), and to engage with the abutment surface to prevent distal displacement of the needle shield element (11) from the partially retracted position.

19. 19. An injection device according to claim 18, wherein the flexible arm is attached to the locking button (25) and the rigid stop member is provided on the needle shield element (11).

20. 20. The injection device of claim 19, wherein the flexible arm is a metallic blade extending axially and attached at one end to the locking button (25), the other end of the blade being a free end having an edge that engages with the lateral abutment surface in the locked position.

21. 17. An injection device according to claim 16, further comprising biasing means for biasing the needle shield element (11) towards its fully extended position.

22. 17. The injection device of claim 16, wherein the needle shielding element (11) comprises a substantially cylindrical wall (91) suitable for shielding a needle (61) attached to the drug cartridge (7) in the fully extended position, and an axial arm (105) protruding proximally from the cylindrical wall (91) and comprising the second locking member.

23. 23. An injection device as described in claim 22, wherein the needle shield element (11) further comprises a guide element (93) protruding proximally from the cylindrical wall (91) for axially guiding the needle shield element (11) as it moves between the fully extended position and the fully retracted position.

24. 23. An injection device according to claim 22, wherein the needle shield element (11) further comprises an enlarged gripping portion at a distal end of the cylindrical wall (91) extending radially beyond the cylindrical wall (91), the enlarged portion engaging a distal edge of the housing (2) in the fully retracted position, thereby preventing further retraction of the needle shield element (11).

25. 25. The injection device of claim 24, wherein the gripping portion has a ridged surface to enhance grip by a user.

26. 23. An injection device according to claim 22, wherein the needle shield element (11) further comprises an axially extending retaining arm (97) projecting proximally from the cylindrical wall (91) and provided with a stop member, the stop member being suitable for engaging a complementary stop member fixed to the housing (2) in the fully extended position to limit the distal displacement of the needle shield element (11).

27. An injection device according to any one of claims 16 to 26, further comprising: an electronic control system for controlling the injection drive mechanism (9) based on user input and information indicative of the state of the device; a position sensing function for detecting the position of the needle shield element (11) and passing corresponding information to the electronic control system; The position sensing mechanism comprises a magnetic portion (117) provided on the needle shielding element (11) and at least a first electromagnetic sensor (201) fixedly arranged within the housing (2), the magnetic portion (117) being movable together with the needle shielding element (11) between a position spaced apart from the first electromagnetic sensor (201) and a position adjacent to the first electromagnetic sensor (201) when the needle shielding element (11) is in its fully retracted position, and the first electromagnetic sensor (201) generates a signal indicating that the injection device (1) is pressed against an injection surface and is ready for injection, and passes the signal to the electronic control system.

28. 28. An injection device according to claim 27, wherein the needle shielding element (11) further comprises an axially extending detection arm (115) protruding proximally from the cylindrical wall (91) and provided with the magnetic portion (117).

29. 28. The injection device of claim 27, further comprising a second electromagnetic sensor (202) fixedly disposed within the housing (2) and axially spaced from the first electromagnetic sensor (201) in the distal direction by a distance corresponding to the movement of the needle shield element (11) between the fully retracted position and one of the partially retracted positions, wherein when the magnetic portion (117) is in the vicinity of the second electromagnetic sensor (202), a signal is generated by the second electromagnetic sensor (202) and passed to the electronic control system indicating that the needle shield element (11) is in a position suitable for the user to attach a needle (61) to the cartridge (7).

30. 28. An injection device according to claim 27, further comprising a body (3) disposed within and fixedly attached to the housing (2), the injection drive mechanism (9) being attached to the body (3).

31. 31. An injection device according to claim 30, which relies on claim 23, wherein the body (3) comprises complementary guide elements (41) which engage with each guide element (93) of the needle shield element (11) to axially guide the needle shield element (11) as it moves between the fully extended position and the fully retracted position.

32. 31. An injection device according to claim 30, wherein the electronic control system comprises a processor and a printed circuit board (32) fixedly arranged within the housing (2), and the electromagnetic sensors (201, 202) are carried by the printed circuit board (32) and connected to the processor to pass signals indicative of the position of the needle shield element (11) to the processor.

33. 28. An injection device as described in claim 27, wherein the electronic control system is adapted not to activate the injection drive mechanism (9) to release the liquid medication from the cartridge (7) unless the electromagnetic sensor (201) passes a signal indicating that the injection device (1) is pressed against an injection surface and is ready for injection.

34. 28. An injection device according to claim 27, wherein the injection drive mechanism (9) comprises an axially displaceable piston rod for driving pistons (65, 66) in the cartridge (7) and an electric motor (83) for displacing the piston rod (81), the electric motor (83) being controlled by the electronic control system.

35. 1. An injection device comprising: an elongate housing (2) extending along a longitudinal axis (X) and configured to receive a medication cartridge (7); an injection drive mechanism (9) for driving pistons (65, 66) within said cartridge (7) and thereby expelling the medicament from said cartridge (7); a needle shielding element (11) telescopically mounted in the housing (2) and axially displaceable between a fully extended position in which the needle shielding element (11) protrudes distally from the housing (2) and is suitable for shielding a needle (61) attached to the cartridge (7), and a fully retracted position spaced proximally from the extended position, corresponding to a situation in which the device (1) is pressed against an injection site to inject the medicament; an electronic control system for controlling the injection drive mechanism (9) based on user input and information indicative of the status of the device (1); the injection device (1) further comprises a position sensing function for detecting the position of the needle shield element (11) and passing corresponding information to the electronic control system; The position detection mechanism comprises a magnetic portion (117) provided on the needle shielding element (11) and a first electromagnetic sensor (201) fixedly arranged within the housing (2), the magnetic portion (117) being movable together with the needle shielding element (11) between a position spaced apart from the first electromagnetic sensor (201) and a position adjacent to the first electromagnetic sensor (201) when the needle shielding element (11) is in its fully retracted position, the first electromagnetic sensor (201) generating a signal to pass to the electronic control system indicating that the injection device (1) is pressed against an injection surface and is ready for injection.

36. 36. An injection device as described in claim 35, wherein the electronic control system is adapted not to activate the injection drive mechanism (9) to release the liquid medication from the cartridge (7) unless the electromagnetic sensor (201) passes a signal indicating that the injection device (1) is pressed against an injection surface and is ready for injection.

37. 37. An injection device according to claim 36, wherein the injection drive mechanism (9) comprises an axially displaceable piston rod (81) for driving pistons (65, 66) in the cartridge (7), and an electric motor (83) for displacing the piston rod (81), the electric motor (83) being controlled by the electronic control system.

38. 36. An injection device according to claim 35, further comprising a body (3) disposed within and fixedly attached to the housing (2), the injection drive mechanism (9) being attached to the body (3).

39. 39. An injection device according to claim 38, wherein the electronic control system comprises a processor and a printed circuit board (32) fixedly arranged within the housing (2), and the electromagnetic sensor (201) is supported by the printed circuit board (32) and connected to the processor so as to pass a signal indicative of the position of the needle shield element (11) to the processor.

40. 36. An injection device according to claim 35, further comprising biasing means for biasing the needle shield element (11) towards its fully extended position.

41. An injection device as claimed in any one of claims 35 to 40, wherein the needle shielding element (11) comprises a substantially cylindrical wall (91) suitable for shielding a needle (61) attached to the drug cartridge (7) in the fully extended position, and an axially extending detection arm (115) projecting proximally from the cylindrical wall (91) and comprising the magnetic portion (117).

42. 42. An injection device as described in claim 41, wherein the needle shield element (11) further comprises a guide element (93) protruding proximally from the cylindrical wall (91) for axially guiding the needle shield element (11) as it moves between the fully extended position and the fully retracted position.

43. 43. An injection device according to claim 42, which is dependent on claim 38, wherein the body (3) comprises complementary guide elements (41) which engage with each guide element (93) of the needle shield element (11) to axially guide the needle shield element (11) as it moves between the fully extended position and the fully retracted position.

44. 42. An injection device according to claim 41, wherein the needle shield element (11) further comprises an enlarged gripping portion at the distal end of the cylindrical wall (91) extending radially beyond the cylindrical wall (91), the enlarged portion engaging a distal edge of the housing (2) in the fully retracted position, thereby preventing further retraction of the needle shield element (11).

45. 45. The injection device of claim 44, wherein the gripping portion has a ridged surface to enhance grip by a user.

46. 42. An injection device according to claim 41, wherein the needle shield element (11) further comprises an axially extending retaining arm (97) protruding proximally from the cylindrical wall (91) and provided with a stop member which, in the fully extended position, is adapted to engage a complementary stop member fixed to the housing (2) to limit the distal displacement of the needle shield element (11).

47. 41. The injection device of any one of claims 35 to 40, further comprising a locking mechanism operable by a user to releasably lock the needle shield element (11) in a partially retracted position spaced proximally from the fully extended position and spaced distally from the fully retracted position, the partially retracted position being suitable for facilitating attachment of a needle (61) to the cartridge (7); the locking mechanism comprises a locking button (25) actuated by a user to be displaced between an unlocked position and a locked position, a first locking member (151) attached to the locking button (25), and a corresponding second locking member (105) provided on the needle shield element (11), wherein the displacement of the needle shield element (11) defines a sliding path for the second locking member (105); The locking mechanism is designed so that the locking button (25) is disengaged from the sliding path of the second locking member (105) when the locking button (25) is in the released position and is in the sliding path when the locking button (25) is in the locked position, and so that in the locked position the first and second locking members engage to prevent distal displacement of the needle shield element (11) from the partially retracted position but allow proximal displacement of the needle shield element (11).

48. 48. An injection device according to claim 47, wherein the locking button (25) projects outwardly from the housing (2) and is laterally displaceable between the release position and the lock position.

49. 48. The injection device of claim 47, wherein one of the first and second locking members has a rigid stop member formed with a lateral abutment surface and an inclined ramp (110), and the other of the first and second locking members has a flexible arm (151) that, in the locked position, is adapted to engage with the ramp and flex and expand to allow proximal displacement of the needle shield element (11), and to engage with the abutment surface to prevent distal displacement of the needle shield element (11) from the partially retracted position.

50. 50. An injection device according to claim 49, wherein the flexible arm is attached to the locking button (25) and the rigid stop member is provided on the needle shield element (11).

51. 51. An injection device as described in claim 50, wherein the flexible arm is a metallic blade extending axially and attached at one end to the locking button (25), the other end of the blade being a free end having an edge that engages with the lateral abutment surface in the locked position.

52. 48. The injection device of claim 47, further comprising a second electromagnetic sensor (202) fixedly disposed within the housing (2) and axially spaced from the first electromagnetic sensor (201) in the distal direction by a distance corresponding to the movement of the needle shield element (11) between the fully retracted position and one of the partially retracted positions, wherein when the magnetic portion (117) is in the vicinity of the second electromagnetic sensor (202), a signal is generated by the second electromagnetic sensor (202) and passed to the electronic control system indicating that the needle shield element (11) is in a position suitable for the user to attach a needle (61) to the cartridge (7).

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