Abstract:
The present invention relates to a medicament delivery device comprising: a housing ( 10, 16 ) having a distal and an proximal end, said housing being adapted to receive a medicament container ( 18 ) with a delivery member ( 20 ) or with a connectable delivery member for delivery of a medicament; a drive mechanism ( 54 ) arranged to act on a plunger rod ( 58 ), which plunger rod ( 58 ) in turn is arranged to act on the medicament container ( 18 ) for providing automatic delivery of the medicament; a release mechanism ( 62 ) interactively connected to the drive mechanism ( 54 ) for releasing the drive mechanism ( 54 ) from a pre-tensioned state; a signal generating mechanism ( 90 ) for generating an audible and/or tactile and/or visual signal indicating that the medicament has been completely delivered, which signal generating mechanism ( 90 ) is operably connected to said drive mechanism such that it is arranged movable in a longitudinal direction in relation to said drive mechanism ( 54 ), that said drive mechanism ( 54 ) is arranged with a signal release mechanism ( 111 ) capable of activating said signal generating mechanism ( 90 ) at a certain longitudinal position of said drive mechanism after its release, for generating an audible and/or tactile and/or visual signal, wherein said signal generating mechanism ( 90 ) comprises a signal delay mechanism ( 105 ) operably arranged to delay the generation of signal after activation of said signal generating mechanism ( 90 ).

Description:
TECHNICAL AREA 
       [0001]    The present invention relates to a medicament delivery device and in particular to a device capable of indicating to a user when a medicament delivery sequence has been completed such that it is safe to remove the device from the dose delivery site. 
       BACKGROUND OF INVENTION 
       [0002]    Many medicament delivery devices are developed for self-administration, i.e. a user performs the medicament delivery her-, or himself. This requires a medicament delivery device, which is reliable, accurate, safe and easy to use. In order to meet these requirements, the risk of human errors must be minimized, the number of actions needed to be performed in order to receive a dose need to be reduced and the device must be intuitive to use. Thus, in order to minimize the risk of human errors, it is desirable to have a device that accurately provides a user with confirmation that he/she has received a complete dose of medicament. 
         [0003]    Medicament delivery devices such as injection devices providing automatic or manual delivery member insertion, automatic injection of a medicament, automatic delivery member retraction or automatic covering of the delivery member are known in the art. Though these injection devices provide many benefits, there is always room for improvement. For example, a device that provides both a complete delivery of medicament and release of a member that produces a reliable audible and/or tactile and/or visible confirmation to the user that the delivery has been completed has hitherto required extremely tight tolerances during manufacturing. 
         [0004]    For example, release of a member that produces a reliable audible and/or tactile and/or visible confirmation to the user that the delivery has been completed is disclosed in WO2011043714A1. The release is accomplished by disengaging a plunger rod from a second activator member once the plunger rod has terminated its displacement for delivering the medicament. The termination of the plunger rod displacement and the disengaging of the plunger rod from the second activator member must occur simultaneously if both a complete delivery of a medicament and a release of the second activator member which produces the reliable audible and/or tactile and/or visible confirmation to the user that the delivery has been completed are to be accomplished. 
         [0005]    Thus, in WO2011043714A1 there is only one mechanical position that is used to activate the release of the second activation member at the point where it is expected that the plunger displacement will terminate. The precision of the timing of the termination of plunger displacement and disengagement of the plunger from the second activation member relies on the manufacturing and assembly dimensions of the parts of the device and thus the tolerances play an important role in the proper functioning of the device. 
         [0006]    Thus, in order to compensate for component tolerances a signal generating member needs to be released before the plunger displacement has terminated. A user may then be prone to remove the device from the delivery site, accidentally causing interruption of the medicament delivery. In order to ensure a complete and accurate delivery of a medicament, all the parts or components of the device must be manufactured to very tight tolerances, leading to high manufacturing and assembling costs. 
         [0007]    Thus, it would be an improvement in the art to provide a medicament delivery device that can be manufactured and assembled, having reliable functions, such as a complete delivery of a medicament followed by an audible and/or tactile and/or visible confirmation to the user that the delivery has been completed. 
       BRIEF DESCRIPTION OF INVENTION 
       [0008]    In the present application, when the term “distal part/end” is used, this refers to the part/end of the device, or the parts/ends of the members thereof, which under use of the device is located the furthest away from the medicament delivery site of the patient. Correspondingly, when the term “proximal part/end” is used, this refers to the part/end of the device, or the parts/ends of the members thereof, which under use of the device is located closest to the medicament delivery site of the patient. 
         [0009]    The aim of the present invention is to remedy the drawbacks of the state of the art medicament delivery devices. This aim is obtained by a medicament delivery device comprising the features of the independent patent claim  1 . Preferable embodiments of the invention form the subject of the dependent patent claims. 
         [0010]    According to the present invention, it comprises a medicament delivery device provided with a preferably elongated housing that has a distal end and a proximal end. The housing may be adapted to receive a medicament container with a delivery member. The delivery member may either be attached to the medicament container or be made integral with it. The delivery member may alternatively be removably connectable to the medicament container. The connection elements may be of different type, like threads, bayonet connections or luer connections, for example. 
         [0011]    The medicament delivery device may further preferably comprise a drive mechanism arranged to act on a plunger rod, where the plunger rod is arranged to act on the medicament container for providing automatic delivery of the medicament. The drive mechanism is preferably pre-tensioned and will preferably interact with a release mechanism. The drive mechanism may on the one hand be automatically operated such that a pressing of the device against a dose delivery site will activate the drive mechanism. On the other hand, the drive mechanism may be manually operated such that the user activates the drive mechanism by e.g. pressing a button or the like. 
         [0012]    According to a preferable solution, the medicament delivery device may comprise a signal generating mechanism for generating an audible and/or tactile and/or visual signal indicating that the medicament has been completely delivered. The signal generating mechanism is preferably operably connected to the drive mechanism such that it is arranged movable in a longitudinal direction in relation to said drive mechanism. The movement in the longitudinal direction facilitates the design and generation of a signal in that very few components or special features are necessary. 
         [0013]    In order to activate the signal generating mechanism, the drive mechanism may preferably be arranged with a release mechanism capable of activating said signal generating mechanism at a certain longitudinal position of said drive mechanism after its release, for generating an audible and/or tactile and/or visual signal. Thus, the signal generating mechanism is activated by the release mechanism at a certain position. This position may be chosen depending on the desired function and desired indication time. In a favourable scenario, the signal may be generated after completed injection sequence so that the user is sure that it is safe to remove the device from the delivery site. 
         [0014]    In order to ascertain that the signal is generated after the injection sequence has ended, the signal generating mechanism may comprise a delay mechanism operably arranged to delay the generation of the signal after activation of said signal generating mechanism. The delay mechanism can be configured to vary the delay time depending on the desired end function. 
         [0015]    According to a favourable solution, the signal generating mechanism may comprise a signal generating element, where the delay mechanism may comprise a friction enhancing element operably connected to said signal generating element and arranged to act between said signal generating element and said drive mechanism. With such a solution, friction is used to delay the signal by slowing the movement of the signal generating element. 
         [0016]    According to one possible solution, the signal generating element may be arranged with a generally tubular body, arranged slidable in a correspondingly shaped passage, and wherein said friction enhancing element is arranged to act between the body and the passage. This may provide a functional and yet simple design where the friction enhancing element is slowing down the movement of the tubular body relative to the passage. 
         [0017]    The passage may have a first section as seen in a longitudinal direction having a diameter such that said friction enhancing element is in contact with the first section, and a second section having a diameter such that the friction enhancing element is not in contact with the second section. Thus the first section sets the length or time the signalling is delayed due to the friction. Then, when the friction enhancing element reaches the second section, the signal generating element is free to move relative the drive mechanism, thereby providing a signal. 
         [0018]    According one aspect of the invention for generating a signal, the signal generating element may be arranged with an abutment surface, operably arranged to interact with a corresponding abutment surface on the plunger rod driver for creating an audible and/or tactile signal when the abutment surfaces are moved in contact with each other. Thus when the second section is reached, the signal element is accelerated until the abutment surfaces hit each other, creating the signal. In that respect, the abutment surfaces may be positioned with a distance between each other when said friction enhancing element is moved from said first section to said second section. 
         [0019]    Further, the signal generating mechanism may comprise radially flexible arms, such that the arms may flex between a holding position and a release position, and wherein the arms are held in a holding position by a radially outwardly positioned support surface, which support surface terminates at said certain longitudinal position of said drive mechanism. In this way, when the arms reach the end of the support surface, the signal generating element is released. This gives a positive and reliable function of the activation. In this respect, the termination of the support surface may be varied in relation to the position of the plunger rod driver, and thus the signal generating mechanism, providing possibilities to vary the activation point in relation to the injection sequence position. 
         [0020]    If the device is intended to be used multiple times, it must be reset and a new medicament container supplied. Thus, also the signal generating mechanism must be reset. The device may therefore also comprise a signal element return mechanism operably connected to the signal generating mechanism for returning the signal element to its initial position when the drive mechanism is returned to its initial position. 
         [0021]    According to an embodiment, the signal element return mechanism may comprise a return element capable of contacting said signal element causing a relative movement between the signal generating element and the drive mechanism. Thus, when the drive mechanism and the signal generating element are moved in the distal direction back to their initial position, the return element will stop the signal generating element causing a relative movement when the drive mechanism continues in the distal direction. 
         [0022]    Further, the support surface may be arranged such as to act on said arms for holding said signal generating element after it has been brought to the initial position by said signal element return mechanism. Thus, the arms are again forced generally radially inwards, thereby locking the signal generating element to the drive mechanism. 
         [0023]    According to a favourable solution, the friction enhancing element may be made of a resilient material. Suitable materials are rubber or plastic, but it is to be understood that other suitable materials may be used. 
         [0024]    According to one solution, the friction enhancing element may be an O-ring. The signal generating element may then be arranged with a groove in which said O-ring may fit. The use of an O-ring provides a simple, yet reliable friction enhancing element of low cost. 
         [0025]    These and other aspects of, and advantages with, the present invention will become apparent from the following detailed description of the invention and from the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0026]    In the following detailed description of the invention, reference will be made to the accompanying drawings, of which 
           [0027]      FIG. 1  shows a perspective view o a non-limiting embodiment of a medicament delivery device, 
           [0028]      FIG. 2  is an exploded view of the embodiment of  FIG. 1 , 
           [0029]      FIGS. 3-9  are detailed views of components comprised in the embodiment of  FIG. 1 , and 
           [0030]      FIGS. 10-20  are detailed cross-sectional views of the embodiment of  FIG. 1 , showing different functional states. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The embodiment shown in the drawings comprises a generally elongated main housing  10  having a distal end  12  and a proximal end  14 ,  FIG. 1 . At the proximal end  14  a proximal housing part  16  is arranged to be releasably attached to the main housing  10  with a first tubular part  16   a,    FIGS. 1 and 2 , having generally the same diameter as the main housing  10 . Attaching elements could comprise threads, bayonet connections, snap-in elements and the like. In the embodiment shown the attaching elements are bayonet connections, as will be described below. The first tubular part  16   a  is arranged to a second tubular part  16   b  having a lesser diameter than the first tubular part  16   a.  As seen in the embodiment of  FIG. 2 , the proximal housing part  16  is arranged in two halves. It is to be understood that other designs are feasible for the desired function and/or due to production aspects. 
         [0032]    The proximal housing part  16  is designed to accommodate a medicament container  18 ,  FIGS. 2 and 3 . An appropriate medicament delivery member  20 ,  FIGS. 2 and 3 , is attached to, or made integral with, the medicament container  18 . A movable stopper  22  is further arranged inside the medicament container,  FIG. 11 . The medicament container  18  is preferably arranged in a medicament container holder  24 ,  FIGS. 2 and 3 . The medicament container holder  24  is arranged to be slidable in the longitudinal direction as will be explained below. 
         [0033]    Surrounding the medicament container holder  24  and coaxial therewith is a medicament delivery member shield  26 ,  FIGS. 3 and 4 . The medicament delivery member shield  26  is arranged with a distal tubular part  28 , which transforms into a proximal tubular part  30 ,  FIG. 4 . In this respect, the inner diameter of the proximal tubular part  30  is somewhat larger than the outer diameter of the medicament container holder  24 . Further, the outer diameter of the proximal tubular part  30  is somewhat smaller than the second tubular part  16   b  of the proximal housing part  16  such that the medicament delivery member shield  26  can move in the longitudinal direction in relation to the proximal housing part  16 . 
         [0034]    An outer surface of the medicament delivery member shield  26  is arranged with threads  32 ,  FIG. 4 , which threads  32  are arranged to cooperate with corresponding threads  34 ,  FIG. 4 , on an inner surface of a generally tubular element  36 , hereafter named depth adjuster. The outer surface of the depth adjuster  36  is arranged with indicia  38 , such as numbers. These indicia  38  are to cooperate with a cut-out  40 ,  FIG. 3 , in the proximal end of the second tubular part  16   b.    
         [0035]    The medicament container holder  24  is further arranged with a circumferential outwardly extending ledge  42  at its distal area,  FIG. 3 . A medicament delivery member return force element  44 , in the embodiment shown arranged as a compression spring, is arranged between a proximally directed surface of the ledge  42  and a distally directed circumferential ledge  46  of the medicament delivery member shield  26 ,  FIG. 4 , wherein the medicament delivery member return force element  44  urges the medicament container holder  24  and the medicament container  18  in the distal direction. The medicament container holder  24  is also arranged with a longitudinal, outwardly directed ledge  48  on its outer surface,  FIG. 3 , which ledge  48  is intended to fit into a longitudinally extending groove  50  in the medicament delivery member shield  26  for guide purposes. Further, the groove  50  ends in a somewhat larger cut-out  52 ,  FIGS. 3 and 4 , in the distal area of the distal tubular part  28  of the medicament delivery member shield, the function of which will be described below. 
         [0036]    The device further comprises a drive mechanism  54 ,  FIGS. 2 and 5 . The drive mechanism  54  comprises a plunger rod driver  56  arranged axially moveable within the main housing  10  between a distal end position and a proximal end position. The proximal end of the plunger rod driver  56  is operably connected to a distal end of an elongated plunger rod  58 ,  FIG. 2 , which in turn abuts the movable stopper  22  in the medicament container  18 . The proximal end position of the plunger rod driver  56  corresponds to a position where the plunger rod  58  and the stopper  22  have been pressed to the end of the stroke of the plunger rod  58 , i.e. the medicament container  18  has been emptied, and the distal end position of the plunger rod driver  56  corresponds to a position where the plunger rod  58  and the stopper  22  have not yet been moved, i.e. the medicament container  18  is full. 
         [0037]    The drive mechanism  54  further comprises a drive spring  60 , shown in the form of a helical coil spring,  FIG. 5 , which biases the plunger rod driver  56  towards its proximal end position. The drive spring  60  is supported by a tubular support element  61  that will prevent buckling of the drive spring  60 . A manually operated release mechanism  62 ,  FIGS. 4 and 5 , for releasing the plunger rod driver  56  of the drive mechanism  54  from the distal, or cocked, position to the proximal, or extended, position is arranged at an outer surface of the housing  10 . The release mechanism  62  is pivotable around a pivoting axle  64 ,  FIG. 5 , between an extended position and a depressed position and comprises a trigger button  66 , which is operably connected to a drive mechanism locking element  68  which locks and interacts with the plunger rod driver  56  via a proximally directed ledge  70  to hold the plunger rod driver  56  with the drive spring  60  in the tensioned state. Adjacent, or at least near, the release mechanism  62 , a status window  72 ,  FIG. 6 , is arranged through which symbols provided on the plunger rod driver  56  are visible to indicate the status of the medicament delivery device. The status window  72  is preferably made of a transparent, or at least translucent, plastic material. 
         [0038]    Further, a blocking mechanism  74 ,  FIG. 6 , is arranged to operatively act on the release mechanism  62  for preventing actuation of the release mechanism  62  in a first position and to allow actuation of the release mechanism  62  in a second position. The blocking mechanism  74  comprises a generally ring-shaped blocking element  76  surrounding the plunger rod driver  56  and is in an initial position positioned distally of the release mechanism  62  such that a part of the blocking element  76  is radially inside the distal end of the trigger button  66 , as shown in  FIG. 6 . In this position, the trigger button  66  is prevented from pivoting around the pivoting axle  64 , thus preventing the activation of the device. 
         [0039]    The ring-shaped blocking element  76  is arranged with two proximally directed arms  78 , which arms  78  are inter-connected by a proximal ring-shaped second element  80 . The arms  78  end in proximally directed end surfaces  82 ,  FIG. 6 . The proximally directed end surfaces  82  are arranged to be in contact with a distally directed end surface  84 ,  FIG. 4 , of the needle shield  26 , the function of which will be described below. The arms  78  are further arranged with cut-outs  86 ,  FIG. 6 , the function of which will be described below. 
         [0040]    According to the embodiment, the device is arranged with a signal generating mechanism  90 ,  FIG. 7 . It comprises a signal generating element  92  comprising an elongated tubular body  94 , provided with a circular end plate  96  with a proximally directed end surface, which is intended to be in contact with a distally directed end surface of the plunger rod  58 . Further, the side surface of the body  94  of the signal generating element  92  is arranged with a circumferential groove  98 ,  FIG. 7 . The body  94  is arranged to fit into a central passage  100  of a tubular element  102  attached to a proximal area of the plunger rod driver,  FIGS. 7 and 8 . The tubular element  102  is arranged with a proximally directed annular surface  104  at the proximal end of the plunger rod driver  56 ,  FIG. 7 . The area of the plunger rod driver  56  proximal of the annular surface  104  has a diameter somewhat larger than the diameter of the end plate  96 , such that the latter may fit into the proximal end of the plunger rod driver  56 . 
         [0041]    Further a signal delay mechanism  105  is arranged,  FIG. 8 . It comprises a friction enhancing element  106  intended to fit into the circumferential groove  98  of the signal generating element  92 . In the embodiment shown the friction enhancing element is an O-ring made of a resilient material such as rubber. The central passage  100  of the tubular element  102  is arranged with a first section  108 ,  FIG. 8 , having a diameter somewhat smaller than the diameter of the O-ring when fitted into the circumferential groove such that the O-ring is compressed when placed in the first section  108 , which first section is comprised in the signal delay mechanism  105 . The central passage  100  is further arranged with a second section  110 ,  FIG. 8 , that has a diameter that is slightly larger than the diameter of the O-ring, the function of which will be described below. 
         [0042]    Further, a signal release mechanism  111 ,  FIG. 8 , is provided on the plunger rod driver  56 . It comprises two arms  112 ,  FIGS. 7 and 8 , attached to the plunger rod driver and extend in the proximal direction, where the arms  112  are positioned on opposite sides of the central passage  100 . Each arm  112  is arranged with a generally radially inwardly directed ledge  114 . The inwardly directed ledges  114  are arranged to extend into cut-outs  116  in the central passage  100 . Further the arms  112  are arranged with generally radially outwardly extending ledges  118 , the function of which will be described below. 
         [0043]    The device is further arranged with a signal element return mechanism  120 ,  FIG. 9 . It comprises a generally cylindrical pusher element  122  arranged slidable inside the support element  61 . The support element  61  is arranged with longitudinally extending grooves  124  on its inner surface and the pusher element  122  is arranged with corresponding ledges  126  that fit into the grooves. The grooves end a certain distance before the proximal end of the support element  61  as seen in  FIG. 9 , whereby the end surface of the groove  124  will provide a stop surface for a proximally directed end surface of the ledges  126 , thereby limiting the movement in the proximal direction of the pusher element  122  relative to the support element  61 . The signal element return mechanism  120  is further provided with a compression spring  128  arranged to act on a distally directed end surface of the pusher element and a fixed wall  130  in the housing  10 , as seen in  FIG. 10 . 
         [0044]    The device is intended to function as follows. When the device is delivered to the user, the medicament delivery member shield  26  is in an extended, proximal position where the medicament delivery member  20  is shielded,  FIG. 6 . There is thus no risk for unintentional needle sticks. The plunger rod  58  is in a distal position where the plunger rod driver  56  is locked in a loaded state with the drive spring  60  compressed as seen in  FIG. 10 . The user then turns the depth adjuster  36  to set the desired or required penetration depth, which is displayed by the indicia  38 . 
         [0045]    The device is now ready to use and the user presses a proximal end of the medicament delivery member shield  26  against a dose delivery site, whereby the medicament delivery member shield  26  is moved in the distal direction inside the housing of the device. Upon pressing the device against the injection site, the medicament delivery member shield  26  also comes into contact with the proximally directed end surfaces  82  of the arms  78  of the blocking mechanism  74 . Thus the ring-shaped blocking element  76  of the blocking mechanism  74  is moved out of blocking position, allowing the release mechanism  62  to be activated. The next step is then for the user to activate the dose delivery sequence. 
         [0046]    According to the embodiment shown, the user depresses the trigger button  66  of the release mechanism  62 , whereby the drive spring  60  is released in that the drive mechanism locking element  68  is moved out of contact with the plunger rod driver  56 . The plunger rod driver  56  and the drive spring  60  then act to force the plunger rod  58  in the proximal direction acting on the stopper  22  inside the medicament container  18 . Since the medicament is incompressible and the passage through the medicament delivery member  20  is narrow, the medicament container holder  24  with the medicament container  18  will be moved in the proximal direction, against the comparatively weak force of the medicament delivery member return force element  44 . 
         [0047]    The movement of the medicament container  18  will now cause a penetration of the medicament delivery member  20  into the skin of the user. The force of the drive spring  60  is far more powerful than that of the medicament delivery member return force element  44 , which therefore is compressed when the drive mechanism  54  is released. The penetration movement is stopped when the circumferential ledge  42  of the distal end of the medicament container holder is adjacent a distally directed stop ledge (not shown) of the medicament delivery member shield  26  with the fully compressed medicament delivery member return force element  44  between the ledges. 
         [0048]    The force of the drive spring  60  now forces the plunger rod  58  in the proximal direction in relation to the medicament container  18 , moving the stopper  22  in the proximal direction, whereby a dose of medicament is delivered into the body of the user. When the plunger rod  58  is moving in the proximal direction, so is the signal generating element  92 . This is due to the arms  112  being forced radially inwards due to the outwardly directed ledges  118  being in contact with an inner surface of the arms  78  of the blocking mechanism  74  as seen in  FIG. 10 . The inwardly directed ledges  114  of the arms  112  are then abutting a distally directed surface, abutment surface, of the end plate  96  of the signal generating element  92 . 
         [0049]    When the plunger rod driver  56 , the signal generating element  92 , the plunger rod  58  and the stopper  22  have reached a position close to the proximal end position of the stopper  22 , the outwardly directed ledges  118  will enter the cut-outs  52  of the medicament delivery member shield  26 , as seen in  FIG. 11 . The arms  112  are then free to move radially outwardly when the outwardly directed ledges enter the cut-outs  52 . Thereby, the inwardly directed ledges  114  will be moved out of contact with the end plate  96  of the signal generating element  92 , as seen in  FIG. 12 . 
         [0050]    The force of the drive spring  60  will continue to urge the plunger rod driver  56  in the proximal direction causing it to move in relation to the signal generating element  92 . However, the relative movement between the plunger rod driver  56  and the signal generating element  92  is slowed due to the friction enhancing element  106  frictionally acting on the inner surface of the tubular element  102  of the plunger rod driver  56 . The friction also aids in transferring some force to the plunger rod  58 , ending the injection sequence. 
         [0051]    The relative movement continues between the plunger rod driver  56  and the signal element  92 . When the friction enhancing element  106  has been moved along the first section  108  it reaches the second section  110 , as seen in  FIG. 13 . Now the friction enhancing element  106  is moved out of contact with the inner surface of the tubular element  102 . As seen, the distally directed surface of the end plate, the abutment surface, is positioned a distance d from the annular surface  104 , an abutment surface. The spring force still acts on the plunger rod driver  56  and since it now can move freely, it will accelerate in the proximal direction the distance d until the proximal annular surface  104 , the abutment surface, of the plunger rod driver  56  hits the distally directed surface, the abutment surface, of the end plate  96  of the signal generating element  92 , as seen in  FIG. 14 . The impact will cause an audible as well as a tactile signal, indicating to the user that the injection sequence has ended and that it is safe to remove the medicament delivery device. In this respect it is to be understood that the length of the first section may be varied in order to vary the delay time before signalling. It is also possible to alter the actuation point by making the cut-outs  52  longer or shorter or to position them differently with respect to the plunger rod driver  56  and its positions during injection. 
         [0052]    When removing the device, since the force on the medicament delivery member shield  26  now is removed at its proximal end, the medicament delivery member return force element  44  will force the medicament delivery member shield  26  in the proximal direction, whereby the medicament delivery member  20  is again shielded by the medicament delivery member shield  26 . In its extended position, the medicament delivery member shield  26  is locked by a medicament delivery member shield locking mechanism (not shown). 
         [0053]    When the device is to be used again, the proximal housing part  16  is removed from the main housing part  10 . This may be done by turning the housing parts in relation to each other, if for instance a bayonet connection is used. 
         [0054]    In order to reset the device the plunger rod driver  56  has to be moved back to its initial position. This may be done by pushing on the plunger rod driver  56  in the distal direction with a suitable tool. This will cause the drive spring  60  to be again tensioned until the drive mechanism locking element  68  grips and holds the plunger rod driver  56 . Before resetting, the signal generating element  92  is still in the distal position and the arms  112  are in their outwardly flexing position, as seen in  FIG. 15 . When the plunger rod driver  56  now is moved back in the distal direction, the outwardly extending ledges  118  will come in contact with the arms  78  of the release mechanism blocking mechanism  74 , and be forced radially inwards, as seen in  FIG. 16 . Since the signal generating element  92  is still in the distal position, the inwardly directed ledges  114  of the arms will be positioned proximally of the end plate  96 , as seen in  FIG. 16 . 
         [0055]    The plunger rod driver  56  continues to be moved distally until the distal end surface of the signal generating element  92  is moved into contact with the pusher element  122  of the signal element return mechanism  120 ,  FIG. 17 . The pusher element  122  is urged in the proximal direction by the spring  128 , which will cause the signal generating element  92  to be moved proximally relative to the plunger rod driver  56  and its tubular element  102  as the latter continues in the distal direction. At a certain position, the outwardly directed ledges  118  will come in position with the cut-outs  86  whereby the arms  112  flex radially outwards, as seen in  FIG. 18 . This enables the end plate  96  of the signal generating element  92  to pass the inwardly directed ledges  114  of the arms  112  and to return to its initial position,  FIG. 19 , thereby resetting the signal mechanism. 
         [0056]    The pushing of the plunger rod driver  56  in the distal direction can now be ended. The plunger rod driver  56  will now slide in the proximal direction by the force of the compression spring  60  until the drive mechanism locking element  68  grips into the ledge  70  of the plunger rod driver. The proximal movement of the plunger rod driver  56  causes the outwardly directed ledges  118  of the arms  112  to be moved out of the cut-outs  86 , and again causes the arms  108  to be pushed radially inwards, thereby positioning the inwardly directed ledges  114  on the distal side of the end plate  96  of the signal element,  FIG. 20 . The device is now ready to be used for a subsequent injection. 
         [0057]    It is to be understood that the embodiment described above and shown in the drawings is to be regarded only as a non-limiting example of the invention and that it may be modified in many ways within the scope of the patent claims.