Abstract:
A control mechanism for a medicament delivery device is provided having a medicament container connection mechanism, for connecting a medicament container with a medicament delivery member; a penetration and withdrawal mechanism, for actuating a penetration and a withdrawal sequence; a medicament delivery drive unit, for expelling a medicament; an activation mechanism, for initiating a penetration and medicament delivery sequence; a stop mechanism, for initiating a withdrawal sequence; wherein the control mechanism further comprises a control member, linearly movable between a first position and a second position, which control member is connectable to the medicament container connection mechanism, to the penetration and withdrawal mechanism, to the medicament delivery drive unit, to the activation mechanism, and to the stop mechanism.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a U.S. National Phase application pursuant to 35 U.S.C. §371 of International Application No. PCT/EP2015/072815 filed Oct. 2, 2015, which claims priority to Swedish Patent Application No. 1451347-7 filed Nov. 10, 2014. The entire disclosure contents of these applications are herewith incorporated by reference into the present application. 
     
    
     TECHNICAL AREA 
       [0002]    The present disclosure relates to a control mechanism for a medicament delivery device and in particular to a device of limited size, capable of accurately controlling a number of functions of a medicament delivery device. 
       BACKGROUND 
       [0003]    For a number of years, infusers have been used that provide the patient or user with the means for administering a drug in an easy way without requiring a medically trained person, such as a physician or a nurse, to handle the device. 
         [0004]    In order to reduce the size of the infuser, a number of alternative designs regarding the plunger rod have been developed, in particular since the plunger rod conventionally is an elongated rod having a length that enables it to empty a tubular medicament container. Document EP 1 326 659 discloses an injecting device having a flexible plunger rod bendable around a guiding wheel. The plunger rod is driven by an electric motor, via a transmission, to empty a medicament container. The drawback with the solution according to EP 1 326 659 is that the guiding wheel is rather large and is positioned behind the medicament container, as seen in a longitudinal direction, making the device unnecessary long. 
         [0005]    Document WO 2010/112377 discloses a reusable medicament delivery device. In order to reduce the length of the device, the plunger rod is arranged in two telescopically arranged parts. The telescopic action requires two compression springs, rendering the device rather long. The device is further arranged with an electric motor. The motor, operably connected to an elongate member, is arranged to control the dose delivery movement of the plunger rods. Further, the motor is also used for retracting the plunger rods after completed dose delivery in order to be able to replace the medicament container. 
         [0006]    Another drawback with many of the mentioned devices is that there is no feature or mechanism for handling the injection needle after completed injection. When the device is withdrawn, the injection needle is completely exposed and may cause injuries to persons handling the device after use. 
       SUMMARY 
       [0007]    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/are located closest to the medicament delivery site of the patient. 
         [0008]    The aim of the present disclosure is to provide a control mechanism having a number of automatic features and wherein the number of components is kept as low as possible. 
         [0009]    The control mechanism according to the present application is adapted for a medicament delivery device, which medicament delivery device preferably comprises 
         [0010]    a medicament container connection mechanism, for connecting a medicament container with a medicament delivery member; a penetration and withdrawal mechanism, for actuating a penetration and a withdrawal sequence; a medicament delivery drive unit, for expelling a medicament; an activation mechanism, for initiating a penetration and medicament delivery sequence; a stop mechanism, for initiating a withdrawal sequence; wherein said control mechanism further comprises a control member, linearly movable between a first position and a second position, which control member is directly connectable to the medicament container connection mechanism, to the penetration and withdrawal mechanism, to the medicament delivery drive unit, to the activation mechanism, and to the stop mechanism, such that the different functions are actuated by the single control member. 
         [0011]    According to a further aspect, the control member is directly connected to the activation mechanism when the control member is in the first position, and the control member is directly connected to the penetration and withdrawal mechanism and to the medicament container connection mechanism during linear movement of the control member between the first and the second position, and the control member is also directly connected to the medicament delivery drive unit and to the stop mechanism when the control member is in the second position. The control member is manually actuatable when it is in the first position or in the second position. 
         [0012]    According to a another aspect, the activation mechanism comprises a manually actuated first locking element and wherein the control member comprises a first recess in which said first locking element is accommodated, such that the control member is directly connected to the activation mechanism when the control member is in the first position. The first locking element is connected to a push button of the activation mechanism, which push button may be pressed by a user to actuate the control mechanism. 
         [0013]    According to yet a further aspect, the control member is releasably held in the first position by said first locking element against a bias of a pre-tensioned first force element, and wherein manual actuation of the first locking element releases the control member to move linearly from the first position towards the second position under the bias of the first force element. 
         [0014]    According to yet another aspect, the first force element comprises a first anchoring element and the control member comprises a first seat and wherein the first anchoring element is releasably connected to the first seat, and configured to be disconnected from the first seat when the control member arrives at the second position. 
         [0015]    According to a another aspect, the medicament delivery drive unit comprises an electrical circuit having a second lead and a third lead and wherein the control member comprises a conductive surface to which said second lead and said third lead are directly connected when the control member is in the second position such that said electrical circuit is closed. 
         [0016]    According to a further aspect, the stop mechanism comprises a manually actuated second locking element and wherein the control member comprises a second recess in which said second locking element may be accommodated, and configured such that the control member is directly connected to the stop mechanism when the control member arrives at the second position. 
         [0017]    According to one aspect, the control member may further be releasably held in the second position by said second locking element against a bias of a pre-tensioned second force element, and wherein manual actuation of the second locking element releases the control member to move linearly from the first position towards the second position under the bias of the second force element. Accordingly, the control element is stationary in the second position, keeping the circuit closed, until the stop mechanism is actuated by a user pressing a push button of the stop mechanism. 
         [0018]    According to yet an aspect, the second force element comprises a second anchoring element and the control member comprises a second seat and wherein the second anchoring element is configured to be connected to the second seat when the control member arrives at the second position. 
         [0019]    According to a further aspect, the penetration and withdrawal mechanism comprises a pinion arranged on a rotatable sleeve, and the control member comprises a toothed rack, and wherein linear movement of the control member between the first position and the second position causes rotation of said rotatable sleeve via interaction between said pinion and said toothed rack. Since a delivery member, e.g. a needle, is threadedly connected to the rotatable sleeve, rotation of the sleeve causes a penetration or a withdrawal of the delivery member when the control member moves between the first position and the second position. 
         [0020]    According to one further aspect, the medicament container connection mechanism comprises a movable body arranged with a ledge, and the control member comprises a slit, which slit has a stop surface, and wherein linear movement of the control member from the first position to the second position causes movement of the body via interaction between said ledge and said stop surface. Such a body may comprise a piercing needle that is moved to penetrate a septum of a medicament container. The piercing needle may also be connected to the delivery member via a flexible tube, such that piercing of the septum connects the drug of the medicament container with the delivery member. 
         [0021]    In order to expel doses of medicament from the medicament container to the medicament delivery member, the drive unit may further comprise a plunger rod, which plunger rod may comprise a number of distinct separate segments being inter-connectable to each other for forming an elongated plunger rod. The use of distinct separate segments enables a very compact device because the elongated plunger rod is “built” by separate successive segments, one at a time. Since the segments are separate, the segments may be packed closely together. There is no need to make room for a plunger rod that is bent or arch-shaped. Thus, the length of a conventional elongated plunger rod does not dictate the size of the medicament delivery device in the present case. 
         [0022]    In order to drive the plunger rod into the medicament container for expelling a dose of medicament, the plunger rod elements may be arranged with threads, designed to interact with a plunger rod drive wheel rotatably connected to an electric motor of the drive unit. 
         [0023]    These and other aspects of, and advantages with, the present disclosure will become apparent from the following detailed description of the disclosure and from the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0024]    In the following detailed description of the disclosure, reference will be made to the accompanying drawings, of which 
           [0025]      FIG. 1  is a perspective view of a medicament delivery device where one housing part is detached for clarity, 
           [0026]      FIG. 2  is another perspective view of the medicament delivery device of  FIG. 1  with a housing part removed, 
           [0027]      FIG. 3  is a perspective view of the medicament delivery device of  FIG. 1  turned 180 degrees in relation to  FIG. 2 , 
           [0028]      FIGS. 4 to 13  show different detailed views of components comprised in the medicament delivery device of  FIG. 1 , and 
           [0029]      FIGS. 14 to 22  show different functional states of the medicament delivery device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    The exemplary embodiment shown in the drawings comprises a proximal housing part  10  and a distal housing part  12 . It is however to be understood that the device can comprise further housing parts depending on design and production issues. The distal housing part  12  is arranged to accommodate a number of elements and mechanisms. Preferably, the assembled housing has a generally flat, rectangular shape having a measure or thickness, viewed along a proximal-distal axis, PD, that is much less than the dimensions in the other two directions, vertical axis VA and horizontal axis HA. 
         [0031]    An activation mechanism  14  is arranged in the device for activating different functions of the device as will be described, see  FIG. 2 . The activation mechanism  14  comprises a push button  16 , extending through a passage  18  of the distal housing part  12 . The push button  16  comprises a generally tubular body  20  provided with an end wall  22 ,  FIG. 4 , which acts as contact surface for a user as will be described. The push button  16  may be arranged with indicia that provide the user with information regarding its function, such as the word ON, indicating to a user that this is the button that activates the device. A centrally positioned shaft  24  is arranged on the end wall, extending in the proximal direction. The shaft  24  is arranged to fit into a generally tubular guide post  26  in the proximal housing part  10 ,  FIG. 5 . The body  20  of the push button  16  is further arranged with two longitudinally extending ledges  28 ,  FIG. 4 b   , arranged opposite each other. The ledges  28  are attached such that they extend a distance radially from the side surface of the tubular body  20 . A distally directed stop surface  30  is thereby formed on each ledge  28 , which stop surface  30  is in contact with an inner surface  31 ,  FIG. 1 , of the distal housing part  12  around the passage  18 , when the push button  16  is forced in the distal direction as will be described. 
         [0032]    Further a proximally directed stop surface  32  is formed by the opposite end of the ledge  28 , which stop surface  32  is intended to come in contact with an inner surface of the proximal housing part  10  when the push button  16  is pressed, thereby limiting the movement of the push button  16 . The body  20  of the push button  16  is further arranged with an extension  34  in the proximal direction. On the extension  34  an elongated ledge  36  is integrated, which ledge  36  extends on both sides of the extension  34  and the body  20 . The side surface of the elongated ledge  36  facing radially inwards is arranged with an inclined surface  38 ,  FIG. 4   a.    
         [0033]    The activation mechanism further comprises a support element  40  in the form of an arc-shaped elongated plate, operably connected to the push button  16 ,  FIG. 4 , hereafter named wedge lock pin. Generally in the centre of the wedge lock pin, a protrusion  42  is arranged, forming a first locking element. The end surface of the protrusion  42  is arranged with a bevelled surface  44  at one corner and a cut-out  46  at the other corner. The protrusion  42  is further arranged with a central slit  48 , through which the elongated ledge  36  fits such that the inclined surface  38  of the elongated ledge  36  is in contact with an inclined surface  50  arranged between the central slit  48  and a longitudinal slit  52  in the wedge lock pin  40 , as seen in  FIG. 4 b   . The wedge lock pin  40  is seated with a proximal end in a seat  54  in the proximal housing part,  FIG. 6 . The distal end of the wedge lock pin  40  extends into the interior of the body  20  of the push button  16 . 
         [0034]    The protrusion  42  of the wedge lock pin  40  is accommodated in a first seat  56  on a first side surface  58  of a generally plate-shaped control element  60 ,  FIG. 4 , comprised in a control mechanism  62 . A second seat  64  is further arranged on the first side surface  58  of the control element, offset in relation to the first seat  56 . Further, the first side surface  58  of the control element  60  is arranged with power connection elements in the form of a surface  66  of conductive material, the function of which will be described below. The first side surface  58  is further arranged with a toothed rack  68 . Further the first side surface  58  is arranged with a third seat  70  positioned in a longitudinally extending groove  72 , which groove  72  extends the whole width of the control element  60 . 
         [0035]    The opposite side surface, i.e. the second side surface  76 , is also arranged with a first seat  78  as well as a groove  80 . In this case the groove  80  extends only to one end of the control element  60 . The second side surface  76  is further arranged with a longitudinally extending first ledge  82 . A second longitudinally extending ledge  84  is positioned parallel with, and at a distance to, the first ledge  82 . The second ledge  84  is further arranged with a third ledge  86  extending a certain length of the second ledge  84 , where the third ledge  86  is positioned 90 degrees in relation to the second ledge  84 . The third ledge  86  thereby extends towards the first ledge  82 , creating an elongated slit  88  between the third ledge  86  and the first ledge  82 . The slit  88  ends in a stop surface  90 . 
         [0036]    The control element  60  is intended to fit into a compartment  92  of the proximal housing part  10 ,  FIG. 5 , which compartment  92  is delimited by two parallel wall sections  94 ,  96 ,  FIGS. 5 and 6 , such that the control element  60  is capable of moving or sliding inside the compartment  92  between a first position and a second position, as will be described below. The wall section  94  that is facing the first side surface  58  of the control element  60  is arranged with a recess  98 ,  FIG. 5 . The other wall section  96  is arranged with a cut-away portion  100 . The function of the recess  98  and the cut-away portion  100  will be described below. 
         [0037]    Further, a first thin band-shaped element  102 , a penetration ribbon,  FIG. 7 , is connected to the control element  60  via an first anchoring element  104  attached to one end, which first anchoring element  104  fits into the first seat  78  on the second side surface  76  of the control element  60 . The penetration ribbon  102  is guided around two posts  106 , fixed on the proximal housing part  10 , and the second end of the penetration ribbon  102  is connected to the free end of a first force element in the form of a clock spring  108 , hereafter named penetration spring. The penetration spring  108  is wound around a further post  110  fixed in the proximal housing part  10  and with an inner end attached to the post  110 . 
         [0038]    A second thin band-shaped element  112 , a retraction ribbon, is arranged with an second anchoring element  114  attached to an end, which second anchoring element  114  fits into the recess  98  in the wall section  94  of the compartment  92 . The retraction ribbon  112  is also guided around two fixed posts  116 . A second force element in the form of a clock spring  118 , hereafter named retraction spring, is attached to the free end of the retraction ribbon  112 . The retraction spring  118  is wound around and attached to, a fixed post  120 . 
         [0039]    Further, a stop mechanism  121  is arranged in the device for stopping different functions of the device as will be described, see  FIG. 2 . The stop mechanism  121  comprises a push button  122  is arranged to the device,  FIG. 8 . It comprises a button with the same design as the start button, i.e. having a central body  124  as well as a shaft  126 ,  FIG. 8 , which shaft  126  is intended to fit into a guide post  128  in the proximal housing part  10 ,  FIG. 5 . Further, the stop button  122  is operably connected to a support element, a wedge lock pin  130 , which is arranged with a protrusion  132  with a similar design as the one for the start button, thus forming a second locking element. The button and the wedge lock pin are further designed as disclosed in connection with the start button, whereby the details of the components will not be described in detail again. The stop button  122  extends through a passage  133  in the distal housing part  12  adjacent the passage  18  of the start button,  FIG. 1 . The stop button  122  may also be arranged with indicia that provide the user with information regarding its function, such as the word OFF, indicating to a user that this is the button that de-activates the device. 
         [0040]    The toothed rack  68  of the control element  60  is in contact with a pinion  134  of a penetration and withdrawal mechanism  135 ,  FIG. 9 , placed on an outer surface of a generally tubularly shaped rotator sleeve  136 ,  FIG. 9 . The rotator sleeve  136  is journalled on a generally tubular post  138 ,  FIG. 6 , in the proximal housing part  12 . The tubular post  138  is further arranged with two opposite slits  140  extending along the extension of the post  138 . Inside the post  138  a medicament delivery member holder  142 ,  FIG. 9 , is arranged so as to be slidable along the extension of the post  138 . The medicament delivery member holder  142  has a generally tubular body  144  with a diameter somewhat smaller than the diameter of the post  138 . The body  144  is arranged with a wall section  146 , and a medicament delivery member  148  is attached centrally in the wall section  146 . On the outer surface of the body  144 , two oppositely positioned, rectangular, protrusions  150  are arranged. These protrusions  150  have a width that is somewhat smaller than the width of the slits  140  of the post  138  such that the rectangular protrusions  150  can slide along the slits  140  as will be described. At the radially outwardly facing surfaces of the rectangular protrusions  150 , two generally cylindrical protrusions  152  are arranged. These cylindrical protrusions  152  are intended to fit into generally spirally extending grooves  154  on an inner surface of the rotator sleeve  136 ,  FIG. 9 , the function of which will be described below. 
         [0041]    The proximal housing part  10  is further arranged to accommodate a medicament container  156 . In the preferred embodiment, the medicament container comprises a generally tubular body  158  with a first end arranged with a passage. Inside the passage a generally resilient stopper  160  is arranged, closing the passage, which stopper  160  is movable inside the body  158 . The opposite second end of the body is preferably arranged with a neck portion  162 , having a central opening. The opening of the neck portion  162  is sealed by a membrane or septum  161  of a pierceable material,  FIG. 17 . In the vicinity of the neck portion  162  of the medicament container  156 , a medicament container connection mechanism  163  is arranged,  FIG. 10 . The medicament container connection mechanism  163  comprises a piercer  164  that is arranged slidable in the proximal housing part  10 ,  FIGS. 2 and 10 . It comprises a generally tubular movable body  166 ,  FIG. 9 , having an inner diameter somewhat larger than the diameter of the neck portion  162  of the medicament container  156 . The piercer  164  is arranged with a central wall  168 . A hollow piercing needle  170  is attached to the centre of the central wall  168 . The body  166  is further arranged with two generally radially outwardly extending ledges  172 ,  174  on opposite sides. One ledge  172  is arranged to be in contact with a fixed support surface on the proximal housing part  10 . The other ledge  174  is arranged to fit into the slit  88  of the control element  60 , the function of which will be described below. 
         [0042]    The device further comprises a drive unit  176 ,  FIG. 11 . The drive unit  176  comprises an electric motor  178  placed inside the housing and held in place by support surfaces of the proximal housing part  10 . The electric motor  178  is arranged with a drive shaft  180 ,  FIG. 2 . A first cog wheel  182  of a transmission  184  is attached to the drive shaft  180 ,  FIG. 11 . The first cog wheel  182  is in engagement with a second cog wheel  186  of the transmission  184 , where the second cog wheel  186  is journalled in seats  188  in the first housing part  10 ,  FIG. 5 . The second cog wheel  186  is in engagement with circumferentially arranged teeth  190  of a generally ring-shaped plunger rod drive wheel  192 . The inner surface of the plunger rod drive wheel  192  is arranged with threads  194 ,  FIG. 12 . These threads  194  are in turn arranged to be in engagement with thread segments  196  of a first plunger rod element  198 . The first plunger rod element  198  has a generally rectangular shape as seen in a cross-section view, where the thread segments  196  are arranged in the corners of the first plunger rod element  198 , as seen in  FIG. 12 . The proximal end of the first plunger rod element  198  is directed towards the first end of the medicament container  156 , wherein the proximal end of the first plunger rod element  198  is intended to be moved in contact with the stopper  160 , as will be described below. The dimensions of the first plunger rod element  198  are such that it will fit into the tubular body  158  of the medicament container  156 . 
         [0043]    The first plunger rod element  198  is arranged with two longitudinally extending grooves  200  on opposite sides thereof. These grooves  200  are intended to cooperate with guide beams  202  arranged extending from a plunger rod element holder  204 . The guide beams  202  are arranged on opposite sides of a passage  206  in the plunger rod element holder  204 , and the first plunger rod element  198  extends through the passage  206  in an initial position. The guide beams  202  are designed such that they have complementary shapes to, and fit into, the elongated grooves  200  of the first plunger rod element  198 . Radially outwardly directed surfaces of the guide beams  202  are designed with a curved shape so as to act as support surfaces for the plunger rod drive wheel  192 . 
         [0044]    The plunger rod element holder  204  is further arranged with a generally rectangularly shaped storage compartment  208 , which storage compartment  208  has four side walls and extends generally perpendicularly to the passage  206 . In the storage compartment  208 , a number of further plunger rod elements  210  are placed. The further plunger rod elements  210  have a shape generally corresponding to the first plunger rod element as seen in  FIG. 13 , i.e. having a generally rectangular cross-sectional shape, where the corners are provided with thread segments  196 , and with longitudinal grooves  200 . The further plunger rod elements  210  are arranged with first  212  and second  214  connection elements at their ends, where the first plunger rod element  198  is arranged with a first connection element  212  at its distal end. The first connection element  212  comprises a transversally arranged groove  216 . The side edges of the groove  216  are arranged with inwardly directed ledges  218 , where the groove  216  and each ledge  218  form a slit  220 . Stop surfaces  222  are arranged at a lower end of the slits  220  as seen in  FIG. 13 . A flexible tongue  224  is arranged in the groove  216 , having a certain inclination as well as a wedge-shaped end protrusion  226 . 
         [0045]    A subsequent plunger rod element  210  that is placed adjacent the first plunger rod element  198  is arranged with a second connection element  214  at its end facing towards the first plunger rod element  198 . The second connection element  214  comprises two proximally directed ledges  228 , designed with a distance between them, generally corresponding to the width of the groove  216  of the first connection element  212 . At the free ends of the ledges  228  outwardly extending protrusions  230  are arranged, which protrusions  230  have a cross-sectional shape complementary to the shape of the slits  220  such that the protrusions  230  can slide into the slits  220  when a subsequent plunger rod element  210  is moved in a direction transversal to the longitudinal direction of the plunger rod elements, as will be described. 
         [0046]    Further an end surface  232  of the plunger rod element  210  between the protrusions  230  is arranged with a connection element  234 , with which the flexible tongue  224  with its wedge-shaped end protrusion  226  may engage when the plunger rod elements are connected as described. All further plunger rod elements  210  in the storage compartment  208  are arranged with the mentioned first and second connection elements  212 ,  214  so as to create an elongated plunger rod by the interconnected plunger rod elements. The plunger rod elements in the compartment are urged towards the passage  206  by an end piece  236 ,  FIG. 12 , placed at the top of the stack of further plunger rod elements  210  in the storage compartment  208 . The end piece  236  is tensioned by a generally flat band spring element  238  with one end seated in the end piece  236  and the opposite end in contact with the bottom  240 ,  FIG. 11 , of the plunger rod element holder  204 . 
         [0047]    The device is further arranged with a suitable power source  242 ,  FIGS. 2 and 3 , that in the embodiment shown is a battery of a generally flat and circular shape, a so called button cell. It is however to be understood that other types of power sources are feasible within the scope. The poles of the battery are connected to leads where a first lead  244  is connected to an input connector  246  of the electric motor  178 ,  FIG. 3 . A second lead  248  is drawn from the battery to a wall section  250  of the compartment  92  in which the control element  60  can move. The end of the second lead  248  is arranged with a flexible end portion capable of contacting the conductive surface  66  of the control element  60 . Further, a third lead  252  is arranged adjacent the second lead  248 , where the third lead  252  also is arranged with a flexible end portion capable of contacting the conductive surface  66  of the control element  60 . The third lead  252  is then connected to a second input connector  254  of the electric motor. The second and third leads are comprised in the power connection elements as will be described. An electric circuit is thus comprised by the battery, the first, the second and the third leads and the electric motor. The conductive surface  66  serves as a switch of the circuit. When the conductive surface contacts the second and the third leads, the circuit is closed, allowing a current to flow through the circuit to drive the electric motor  178 . 
         [0048]    The device is intended to function as follows. When delivered to a user, it is energized in that the penetration spring  108  is tensioned and held in that state by the first anchoring element  104  engaged in the first seat  78  of the control element  60 , as seen in  FIG. 7 . The control element  60  in turn is held stationary in the first position against the force of the penetration spring  108  by the protrusion  42  of the wedge-lock pin  40  of the ON-button fitting into the first seat  56 , as seen in  FIG. 14 . The retraction spring  118  is also tensioned and held in that state by its second anchoring element  114  seated in the recess  98  of the compartment  92 , as seen in  FIG. 7 . 
         [0049]    When the device is to be used a lid (not shown) on the distal housing part  12  is opened and a medicament container  156  is placed in the interior of the device, after which the lid is closed. The device is then attached to the body of the patient with suitable elements. That could for example be an adhesive on the proximal surface of the proximal housing part  10 , elastic straps around the body of the patient, for example. 
         [0050]    When the device is positioned properly, the user may activate it by pressing the on-push button  16  of the activation mechanism  14 . The push button  16  will then move in the proximal direction inside the housing whereby the inclined surface  38  of the ledge  36  will act on the wedge lock pin  40  such that its central protrusion  42  is moved out of contact with the first seat  56  of the control element  60 , as seen in  FIG. 15 . The control element  60  is now free to move from the first position and will be pulled towards the second position by the pre-tensioned penetration spring  108  fitting in the first seat  78  of the control element  60 . The second anchoring element  114  of the retraction spring  118  is still seated in the recess  98  of the compartment  92  and will slide in the groove  72  of the control element  60  when the latter is moved. 
         [0051]    As the control element  60  moves, its toothed rack  68  will act on the pinion  134  of the rotator sleeve  136 . The rotation of the rotator sleeve  136  will cause the cylindrical protrusions  152  of the medicament delivery member holder  142  to slide in the spiral grooves  154  of the rotator sleeve  136 , whereby the medicament delivery member holder  142  will move in the proximal direction and so will the medicament delivery member  148 , whereby a penetration is obtained,  FIG. 16 . 
         [0052]    The movement of the control element  60  will cause the second ledge  174  of the piercer  164  to come in contact with the stop surface  90  in the slit  88  of the control element  60 . 
         [0053]    This will cause the piercer  164  to move towards the medicament container  156 . The end of the piercing needle  170  will then penetrate the septum  161  of the medicament container, whereby a fluid connection is obtained between the interior of the medicament container  156  and the medicament delivery member  148 ,  FIG. 17 , via a flexible tube (not shown). 
         [0054]    Further movement of the control element  60  will cause the conductive area  66  of the control element  60  to be moved into the second position and into contact with the second and the third leads,  248 ,  252 . In this position, the protrusion  132  of the wedge lock pin  130  of the stop button  122  will enter the second seat  64  of the first side surface  58  of the control element  60 ,  FIG. 18 , thereby locking the control element  60  in this position. The penetration spring  108  is now released from the control element  60  because its first anchoring element  104  has come to the cut-away portion  100  in the wall of the compartment  92  and the second anchoring element  114  of the retraction spring  118  is released from the recess  98  in the side wall of the compartment  92  because the second anchoring element  114  now can slide into the third seat  70  of the control element  60 , as seen in  FIG. 19 . However, the retraction spring  118  is still tensioned since the control element  60  is held by the second locking element  132 . 
         [0055]    Further, the contact of the leads  248 ,  252 , with the conductive area  66 , i.e. the power connection elements, will cause the power source  242  to be connected to the electric motor  178 , thereby energizing the latter to start rotating the first cogwheel  182 . The rotation of the first cogwheel  182  is transmitted to the second cogwheel  186  of the transmission  184  and then to the plunger rod drive wheel  192  via its teeth  190 . Since the threads  194  of the plunger rod drive wheel  192  is in contact with the thread segments  196  of the first plunger rod element  198 , the first plunger rod element  198  is moved in the direction of the medicament container  156 . When the proximal end of the first plunger rod element  198  comes in contact with the stopper  160 , it will move the stopper  160  inside the medicament container towards its neck portion  162 , whereby medicament will be forced through the fluid connection and through the medicament delivery member  148 , thereby delivering medicament to the user. 
         [0056]    When the first plunger rod element  198  has moved a distance towards and inside the medicament container  156 , the space behind the first plunger rod element  198  is so large that a subsequent plunger rod element  210  may be pushed in the vertical direction by the flat band spring element  238  acting on the uppermost positioned end piece  236  in the storage compartment  208 . When the following plunger rod elements  210  are pushed downwards in the vertical direction, they are connected to a previous plunger rod element in that the ledges  228  of the first connection elements  212  of the subsequent segment fit into the slits  220  of the groove  216  of the second connection element  214  and wherein the plunger rod elements are inter-locked by the flexible tongues  224  engaging the connection elements  234 . In this manner a sequential “building” of a continuous plunger rod is performed with the segments while performing injection of medicament from the medicament container  156  through the medicament delivery member  148 , as seen in  FIG. 20 . 
         [0057]    When the plunger rod has pushed the stopper  160  inside the medicament container  156  to the most proximal position, whereby the dose delivery sequence is ended, the device can be switched off. In order to do this the OFF-button  122  is depressed. This causes the protrusion  132  of the wedge lock pin  130  of the OFF-button to be moved out of the second seat  64  of the control element  60 , thereby releasing the control element,  FIG. 21 . Due to the force of the retraction spring  118 , the control element  60  is now moved back to its original position, i.e. the first position,  FIG. 22 . The movement of the control element  60  causes the conductive area  66  to be moved away from the leads  248 ,  252 , thereby breaking the electric connection with the power source  242 , whereby the electric motor  178  is switched off. Further, the movement of the control element  60  will cause its toothed rack  68  to act on the pinion  134  of the rotator sleeve  136 . The rotation of the rotator sleeve  136  in the opposite direction will in turn cause a retraction of the medicament delivery member  148  from its extended position to the initial position where the medicament delivery member is hidden inside the device. The device is now safe to be removed from the body of the user. 
         [0058]    If the device is to be used again, the device is opened in a suitable way and the medicament delivery member holder is replaced with a new clean/sterile holder and medicament delivery member. Further the empty medicament container is replaced with a full medicament container. 
         [0059]    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 disclosure and that it may be modified in many ways within the scope of the patent claims.