Abstract:
An injection device includes a housing; a container holder configured for accommodating a medicament container and having a needle attached to one end thereof and a stopper sealingly and slidably arranged inside the medicament container at the other end thereof; a drive unit, including a plunger rod, a plunger driver, and a first energy accumulating member operationally associated with the plunger driver; and an injection indication mechanism, including a tactile signaling element and a drive mechanism for driving the tactile signaling member, the drive mechanism being coupled to the plunger driver.

Description:
[0001]    The present invention relates to an injection device having several automatic functions such as automatic penetration, automatic injection and automatic safety means for preventing accidental needle sticks and in particular an injection device capable of handling medicament in fluid form having high viscosity. 
       BACKGROUND 
       [0002]    The present invention relates to injection devices for injecting medicament in fluid form having high viscosity which means that these devices require high forces in order to press the fluid through a needle when injecting the medicament. 
         [0003]    Auto-injectors or pen-injectors have been on the market for many years. One of the first auto-injectors was developed for war-times, which was activated by pressing the injector against a body part for activating it. The main concern was to have the medicament injected as fast as possible, without much concern for the patient or for handling safety aspects. During recent years some medicaments have been developed such that these have to be injected by the patients themselves. Therefore, depending on the intended use and type of medicament, injection devices having a varying degree of automatic functions that facilitate the injection of medicaments in a reliable and safe way for patients and even for trained personnel; e.g. physicians, nurses, have also been developed. 
         [0004]    Auto-injector devices having an automated injection function often comprise a housing, a spirally wound compression spring acting on a plunger rod which in its turn acts on a stopper inside a medicament container for expelling the medicament through a needle attached to the container. Normally, one end of the spring often abuts an inner end surface of the housing, which means that the housing has to be dimensioned to the force of the spring. When fluids with high viscosity are to be injected using an auto-injector, high forces are required to expel the medicament through a fine needle. Consequently, the spring becomes very large both regarding the diameter of the wound spring and also the diameter of the thread of the wire. The size of the spring means that the device becomes large, and for some applications and customers, such device sizes are not acceptable. 
         [0005]    Furthermore, in particular when injection of medicament takes a long tome, for example when a high-viscosity liquid is injected and/or a needle having a small diameter is used, the user of the injection device wants to know whether or not the injection is still proceeding. In other words, the user self-administering a medicament needs to be informed when the injection is completed and it is safe to remove the injector from the injection site. 
         [0006]    WO 2004/020028 describes an injection device having a closed scale band. When administering a product, a required dosage is set on the injection device by rotating a rotational button. This transports the scale band in accordance with setting a dosage, such that once the dosage setting rotation is complete, the corresponding dosage unit can be read through a window. Such scale band for dosage indication does however not show the progress of injection. 
         [0007]    An injection device having a band type indicator as suggested in WO 2004/020028 is, however, complex to assemble. Moreover, the movement of the band is visible to the user from one direction or viewing angle (or small band of viewing angles) only. Furthermore, slow injections may be difficult to detect by a user. 
         [0008]    Another means of information regarding the progress of an injection is by tactile means. Document WO 2008/083875 discloses a medical delivery device comprising a tactile information means capable of providing vibration to the device during e.g. an injection cycle. The vibration is preferably generated by an unbalance member. The tactile information member of the device is rather bulky, especially if it is to be fitted into a rather small device, at the same time as the space usually is limited. Also, vibrations of the whole device may be undesirable in some instances and for some patients, desiring more subtle tactile information. 
       BRIEF DESCRIPTION OF INVENTION 
       [0009]    In order to overcome one or several of the above-mentioned problems, an injection device according to independent claim  1  is provided. 
         [0010]    Further aspects, improvements and variations are disclosed in the dependent claims, the figures and the description. 
         [0011]    In the present application, when the term “distal” is used, this refers to the direction pointing away from the dose delivery site. When the term “distal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which is/are located furthest away from the dose delivery site. 
         [0012]    Correspondingly, when the term “proximal” is used, this refers to the direction pointing to the dose delivery site. When the term “proximal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which is/are located closest to the dose delivery site. 
         [0013]    The injection device according to the present invention may comprise a housing, which may be one part or several interconnected and attached parts, such as a proximal housing part, a distal housing part and possibly with intermediate housing parts. 
         [0014]    One of the housing parts may preferably comprise a container holder arranged within said housing, preferably a proximal housing part if the device is provided with several housing parts. The container holder is configured to accommodate a medicament container having a needle attached to one end thereof and a stopper sealingly and slidably arranged inside said medicament container at the other end. 
         [0015]    The device may further comprise a drive unit comprising a plunger rod, arranged to act on the stopper of the medicament container, and a plunger drive means, capable of driving the plunger rod in the proximal direction, thereby moving the stopper. The plunger drive means may be slidably arranged in relation to the plunger rod and may further be rotationally locked to the plunger rod as well as being rotatable in relation to the housing. 
         [0016]    The drive unit may further comprise a first energy accumulating member arranged in the interior of the housing of the injection device and adapted to accumulate and store energy. The energy accumulating member may be some sort of spring that may be tensioned in order to provide energy when the plunger drive means is released. Preferably the first energy accumulating member is a spirally wound spring. Said plunger drive means is preferably operationally associated with said first energy accumulating member. 
         [0017]    The plunger drive means may preferably be releasable such that due to an output torque from said first energy accumulating member, the plunger drive means is allowed to be rotated and the plunger rod is urged towards the proximal end of the injection device whereby an injection is performed. 
         [0018]    According to a main aspect of the invention, the device is arranged with an injection indication mechanism configured for indicating to the user the progress of the injection. The injection indication mechanism may preferably comprise a tactile signalling element and a drive mechanism for driving said tactile signalling member. 
         [0019]    The drive mechanism may be coupled to said plunger drive means at the distal end of said plunger drive means, where the injection indication mechanism may be arranged such that the progress of the injection is felt by a user in that said tactile signalling member is protruding out from a distal end surface of the housing. The tactile signalling member thus provides information to the user via e.g. a finger resting on the distal end of the device or another part of the hand of the user, depending on how the user is holding the device during injection. 
         [0020]    According to one preferred solution, said tactile signalling element may comprise at least one distally directed protrusion arranged to extend through at least one passage arranged in said end surface of the housing. In this manner, the extension of the protrusion provides positive information regarding the progress of the injection. Preferably the injection device may further be arranged such that said drive mechanism is a rotary drive mechanism rotationally locked to said drive means such that rotation of said rotary drive mechanism during injection drives the tactile signalling member in the distal direction thereby indicating the progress of the injection. In this manner it is possible to utilize the rotating motion of the drive means, which is transferred to the rotary drive mechanism, thereby rotationally driving the tactile signalling member. 
         [0021]    In order to transfer the rotational motion to the tactile signalling member, said tactile signalling member may be arranged with thread segments designed to cooperate with corresponding thread segments on said rotary drive mechanism for driving said tactile signalling member. The threaded engagement provides a natural and positive driving force between the components. 
         [0022]    When providing the desired, predetermined tactile information, different components of the device may be modified and designed in order to obtain specific characteristics for the signalling member in order to inform the user of the progress of the injection. The pitch of thread segments may be adapted to obtain a predetermined speed of displacement of the tactile signalling member. The length of protrusions may be varied to obtain the predetermined timing or the tactile experience about the progress of the injection. Similarly, an initial position and/or an end position of said tactile signalling member in relation to said distal end surface of the device may be configured to obtain the desired, predetermined characteristics. 
         [0023]    For instance the length of the protrusions and/or position of the signalling member in relation to the distal end surface may be chosen such that they protrude somewhat already before the injection sequence, for example signalling that the device is ready for use. The pitch may then be chosen such that the protrusions do not extend so much during the injection sequence, just enough to provide tactile information that the injection is in progress. 
         [0024]    On the other hand, the pitch, length and/or position of the signalling member may be chosen such that it protrudes only at the end or last part of the injection sequence, thereby indicating end of injection. 
         [0025]    Further to the tactile signalling, the device according to the present invention may also be arranged with an audio signalling member. According to one aspect of the invention, said rotary drive mechanism may further comprise an audio signalling member configured for audibly indicating to the user the progress of the injection, such that the progress of the injection is heard by the user. This feature provides an additional information source that may increase the overall function and response to the device. For instance, the audio signalling member may be operative during the whole injection sequence while the tactile signalling member is only noticeable during the last phase of the injection. 
         [0026]    Moreover, the signalling member may also provide some tactile information when said audio signalling member comprises at least one flexible member and at least one impact member. Thereby, during rotation of said rotary drive mechanism, said impact member acts on said flexible member such that it rapidly hits a surface, thereby producing a sound as well as providing vibrational tactile information. 
         [0027]    The device may be arranged with further signalling members and in particular said rotary drive mechanism may further comprise a visual signalling member configured for visually indicating to the user the progress of the injection, such that the progress of injection is shown through at least one opening provided at least in a distal end surface of the housing. In this manner the user is also provided with visual information regarding the progress of the injection. 
         [0028]    As with the previously mentioned signalling members, a visual signalling member may also comprise at least one indication element for informing the user that the device is ready for a medicament injection, that the medicament injection is in progress, and that the medicament injection has come to an end. 
         [0029]    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 
         [0030]    In the following detailed description of the invention, reference will be made to the accompanying drawings, of which 
           [0031]      FIG. 1  shows a perspective view of an injection device according to a first preferred embodiment of the invention; 
           [0032]      FIG. 2  shows a first exploded view of the injection device according to the first preferred embodiment of  FIG. 1 ; 
           [0033]      FIG. 3  shows a further exploded view of the injection device according to the first preferred embodiment of the invention; 
           [0034]      FIG. 4  shows a further exploded view of the injection device according to the first preferred embodiment of the invention; 
           [0035]      FIG. 5  shows further components of the injection device according to the preferred embodiment; 
           [0036]      FIG. 6  shows further components of the injection device according to the preferred embodiment; 
           [0037]      FIG. 7  shows a sectional view of the injection device according to the preferred embodiment of the invention in the initial position; 
           [0038]      FIG. 8  shows a perspective view of the injection device according to the preferred embodiment of the invention in the initial position as shown in  FIG. 7 ; 
           [0039]      FIG. 9  shows a perspective view of a second preferred embodiment of the invention; 
           [0040]      FIG. 10  shows a perspective view of details of the second preferred embodiment; 
           [0041]      FIG. 11  shows a perspective view of details of the second preferred embodiment 
           [0042]      FIG. 12  shows a perspective view of details of the second preferred embodiment; 
           [0043]      FIG. 13  shows a perspective view of details of the second preferred embodiment; 
           [0044]      FIGS. 14   a ,  14   b  show detailed cross-sectional views of the tactile indication mechanism of the second preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0045]      FIG. 1  shows a perspective view of an injection device according to a first preferred embodiment of the present invention. The injection device  1  has a housing that comprises a proximal housing part  2 , a distal housing part  3 , a proximal intermediate housing part  4  ( FIG. 2 ), and a distal intermediate housing part  5 . In the assembled state of the injection device  1 , the proximal housing part  2 , the distal housing part  3 , and the distal intermediate housing part  5  form the outer surface or appearance of the injection device  1 . 
         [0046]    As shown in  FIG. 1 , the proximal housing part  2  comprises at least one window  6 . In a preferred embodiment, two such windows are provided located at opposite sides of the proximal housing part  2 . Such windows allow the user to view the state of the injection, i.e. whether the injection device  1  is still in its initial stage with the medicament not yet being injected, or whether the medicament container is already emptied. Through window  6 , the user can see the medicament container accommodated at least in the proximal housing part  2 . 
         [0047]    Furthermore,  FIG. 2  shows front cap  7  which closes the proximal opening of the proximal housing part  2  until the injection device  1  is used. 
         [0048]    In  FIG. 1 , the outer end  41  of a spring can also be seen. This will be described in more detail below. 
         [0049]      FIG. 2  shows a first exploded view of the injection device  1  according to the first preferred embodiment of the present invention. In this exploded view of  FIG. 2 , the proximal housing part  2 , the distal intermediate housing part  5  and the distal housing part  3 , as well as the front cap  7  are shown “removed” from the injection device  1 . Furthermore,  FIG. 2  shows a proximal intermediate housing part  4 . Proximal intermediate housing part  4  forms part of the housing of the injection device  1  but is in fact located in the interior (as clearly shown in the cross-sectional view of  FIG. 7 ) in order to connect the proximal housing part  2  and the distal intermediate housing part  5  with each other. To this end, the outer surface of the proximal intermediate housing part  4  and the inner surfaces of the proximal housing part  2  and the distal intermediate housing part  5 , respectively, are provided with corresponding engagement structures such as circumferential groove-rib-structures, a shown in  FIG. 2 . Thus, the proximal housing part  2  and the distal intermediate housing part  5  can easily be snapped onto the proximal intermediate housing part  4  so that the proximal housing part  2  and the distal intermediate housing part  5  do not fall off of each other. However, the connection between these parts may be releasable so that a medicament container can be inserted into or removed from the proximal part of the injection device  1 . 
         [0050]    As further shown in  FIG. 2 , the injection device according to the first embodiment of the invention comprises a medicament container holder  10 . In the fully assembled state of the injection device  1 , the medicament container holder  10  is at least with its proximal part located within the proximal housing part  2 . This will be described in more detail below with reference to  FIG. 7 . In the preferred embodiment shown in  FIG. 2 , the medicament container holder  10  comprises a first and a second container holder guide  11 . Preferably, the container holder guides  11  are arranged at opposite sides of container holder  10 , and extend in longitudinal direction thereof. The container holder guides  11  are received in corresponding groove structures provided at the inner surface of the proximal housing part  2  so that the medicament container holder  10  is axially movable in relation to the housing but is locked from being rotated relative to the housing, in particular relative to proximal housing part  2 . 
         [0051]      FIG. 2  also shows needle shield sleeve  17  having at its proximal end a needle shield sleeve extension  18 . At its distal end, needle shield sleeve  17  comprises two tongue extensions  19  which are arranged on opposite sites, relative to the longitudinal center axis of the injection device  1 . The proximal part of needle shield sleeve  17  is of generally cylindrical form. The most proximal part is a fully closed cylinder from which the two tongue extensions  19  project and extend towards the distal end of the injection device  1 . In the preferred embodiment shown in the drawings, the tongue extensions  19  basically comprise three areas. The first, most proximal area  191  is formed by two cylinder segments having the same radius/diameter as the closed cylindrical most proximal part of needle shield sleeve  17 . The distal parts or areas  193  of tongue extensions  19  are spaced from each other at a greater distance than the diameter of the cylindrical part. In between of these two areas, an intermediate area  192  is provided that forms a transition between the smaller diameter of the cylindrical area  191  and the greater distance at the distal end  193  of the tongue extensions  19 . In general terms, the needle shield sleeve  17  has a widened configuration in that it widens from the proximal end towards the distal end thereof. 
         [0052]      FIG. 2  further shows proximal housing spring retainer  30  which is generally ring-shaped or substantially ring-shaped, and coaxially arranged with the proximal housing part  2 . The proximal housing spring retainer  30  surrounds a distal area of medicament container holder  10 , i.e. is located as shown in  FIG. 2 , radially between a distal area of medicament container holder  10  and the distal areas  193  of tongue extensions  19 . As shown in more detail in  FIG. 4 , the proximal housing spring retainer  30  comprises two pins  31  that carry springs (not shown In  FIG. 2 ) to push the needle sleeve  17  towards the proximal end of the injection device  1  when the injection device  1  is removed from the injection site after medicament delivery has been performed in order to cover the needle  13 . 
         [0053]      FIG. 2  also shows container driver locking means  25  being a generally ring-shaped element. Container driver locking means  25  is rotatable in relation to the housing and in engagement with the needle shield sleeve  17 . This engagement is described in more detail below with reference to  FIGS. 3 and 4 . 
         [0054]    Distal from container driver locking means  25 , container driver  32  is located. Container driver  32  is arranged for being connectable to the container holder  10 , which will be described in further detail below. 
         [0055]    Furthermore,  FIG. 2  shows a first energy accumulating member, i.e. first spring  40  which is used to perform an injection, and a second energy accumulating member, for example second spring  45  which is used to axially move the medicament container holder  10  in order to perform a needle penetration prior to injection of the medicament. 
         [0056]    Finally,  FIG. 2  shows indicator  80  for indicating end of dose. 
         [0057]    Further parts shown in  FIG. 2  not yet discussed will be discussed in detail below. 
         [0058]      FIG. 3  shows a further exploded view of the injection device  1  according to the preferred embodiment of the present invention. 
         [0059]    In  FIG. 3 , the needle shield sleeve  17 , the needle shield sleeve extension  18 , and the container driver locking means  25  are shown “removed” from the injection device assembly. Furthermore, the proximal intermediate housing part  4  and the first spring  40  are shown as individual components in more detail. 
         [0060]    In  FIG. 3 , one of two opposing groove structures  26  of the container driver locking means  25  is shown in more detail. Each groove structure  26  has two segments, namely an inclined groove  261  and a longitudinal groove  262 . In the initial position of injection device  1 , radial protrusions  20  formed at the inner surface of the distal areas  193  of the tongue extension  19  are located in the inclined groove  261  of the groove structures  26 . When the injection device  1  is placed on an injection site, for example the skin of a user, the needle shield sleeve  17  is thereby pushed or moved towards the distal end of the injection device  1 . Such displacement of the needle shield sleeve  17  causes the protrusions  20  to move in the inclined grooves  261  towards the distal end of the container driver locking means  25  (which is shown by an arrow and drawn in the inclined groove  261  in  FIG. 3 ). Since the container driver locking means  25  is rotatable in relation to the housing but longitudinally fixed (in that it abuts against the container driver  32 ), and the needle shield sleeve is rotationally locked, longitudinal displacement of the needle shield sleeve  17  towards the distal end of the injection device  1  results in a rotational movement of the container driver locking means  25 , allowing the protrusions  20  to slide towards the distal ends of inclined grooves  261 . 
         [0061]    As long as the injection device is pressed on the injection site, i.e. as long as the needle shield sleeve  17  is held in its distal position, the protrusions  20  stay at the distal end of the groove structures  26 . However, when the user removes the injection device  1  from the injection site, for example after medicament delivery, the needle shield sleeve  17  is urged towards the proximal end of the injection device  1 , as described above. During this movement, the projections  20  slide along longitudinal grooves  262  and are locked at the proximal ends of the longitudinal grooves  262  by respective locking structures  28 . This prevents that the needle shield sleeve  17  can again be moved towards the distal end of the injection device  1 . 
         [0062]      FIG. 3  further shows in more detail the medicament container holder  10  with its two container holder guides  11 . Furthermore, one of the two pins  31  of the proximal housing spring retainer  30  extending parallel to the longitudinal axis towards the proximal end of the injection device is shown with its full length. 
         [0063]      FIG. 3  also shows rigid needle shield remover  16 . The rigid needle shield remover  16  comprises at its proximal end an engagement structure, such as a circumferential rib at its outer surface, which is in engagement with a corresponding engagement structure at the inner surface of the front cap  7 , for example a corresponding groove (shown in  FIG. 7 ). Due to such engagement, upon removal of the front cap  7 , the rigid needle shield remover  16  is withdrawn from the medicament container  12 . Furthermore, upon removal of the rigid needle shield remover  16 , the rigid needle shield comprising a soft part  14  and a rigid part  15  (see  FIG. 5 ) are also removed from the medicament container  12  due to respective engagement structures engaging the two parts of the rigid needle shield and the rigid needle shield remover  16  with each other. 
         [0064]      FIG. 3  also shows in more detail the container driver  32 . The container driver  32  comprises at least one rotational locking rib  39 . In the preferred embodiment, four rotational locking ribs  39  are provided, three of which are shown in  FIG. 3 . In the assembled state of the injection device  1 , the rotational locking ribs  39  are located or received in corresponding locking grooves  8  arranged on the inner surface of the proximal intermediate housing part  4 . The locking ribs as well as the corresponding grooves extend in longitudinal direction. Such structure prevents the container driver  32  from being rotated, i.e. the container driver  32  is movable in longitudinal direction relative to the housing but rotationally locked. 
         [0065]    At its proximal side, the container driver  32  comprises at least one container driver arm  33 . In the preferred embodiment shown in the drawings, two container driver arms  33  are arranged (see  FIG. 4 ). The container driver arms  33  each comprise an engagement opening  34  being configured for engagement with corresponding engagement protrusions  36  projecting from container holder tongue extensions  35  provided at the distal end of the container holder  10 . Thus, the medicament container holder  10  is connected with the container driver  32 , and longitudinal displacement of the container driver  32  towards the proximal end of the injection device  1  (by second spring  45 ) results in a movement of the medicament holder  10  towards the proximal end of the injection device  1  whereby a needle penetration is performed. 
         [0066]    As can also be seen in  FIG. 3 , the container driver  32  comprises at least one ledge  37 . In the preferred embodiment, two ledges  37  are provided (as can be seen in more detail in  FIG. 4 ). With these ledges  37 , the container driver  32  initially abuts against stop ribs  27  located at the inner surface of the container driver locking means  25  (the stop ribs  27  are shown in  FIG. 6 ). Thus, in the initial position of the injection device, i.e., prior to its use, the container driver  32  and thus the medicament container holder  10  are prevented from being moved proximally because such movement is blocked by the container driver locking means  25  due to the abutment of the ledges  37  against the stop ribs  27 . Only upon rotational movement of the container driver locking means  25  (caused by distal displacement of the needle shield sleeve  17 ), the stop ribs  27  are moved out of abutment with the ledges  37 . Thus, the container driver is no longer axially locked/blocked by container driver locking means  25 . 
         [0067]      FIG. 3  also shows plunger driver  50 , plunger rod  60 , and plunger drive locking means  70 . These components are described in more detail below. 
         [0068]    Finally, as shown in  FIG. 3 , first spring  40  comprises an outer end  41  which connects the first spring  40  to the housing, i.e. to the distal housing part  3 , and an inner end  42  which connects the first spring  40  to the plunger driver  50 . The outer end  41  may, for example, extend through a longitudinal slit in the distal housing part so that it may be engaged with the wall in the form of a hook. The first end  41  can then be seen at the outside, as shown in  FIG. 1 . Alternatively, the first end of spring  40  is engaged to a mating engagement structure provided at the inner surface of distal housing part  3 . 
         [0069]    In the exploded view of  FIG. 4 , the injection device  1  of the preferred embodiment of the invention is further disassembled. In this drawing, the proximal housing spring retainer  30 , the container driver  32 , and the plunger drive locking means  70  are shown “removed” from the assembly. In  FIG. 4 , the distal end of the medicament container holder  10  is shown uncovered by the container driver  32 . Thus, the two container holder tongue extensions  35  each having an engagement protrusion  36  can easily be seen. 
         [0070]    Furthermore, the two opposing arms  33  of the container driver  32  are shown. In the preferred embodiment, each arm comprises two portions, a first portion extending radially, and a second portion extending in longitudinal direction towards the proximal end of the injection device. Although in the preferred embodiment only two container driver arms  33  and only two corresponding container holder tongue extensions  35  are shown, the invention encompasses other configurations, such as just a single arm-protrusion-pair, or a larger number of arm-protrusion-pairs, such as three or four, for example. Similarly, the container driver  32  may have just a single rotational locking rib  39  but the invention also encompasses container drivers having two, three, five, or six, or even more rotational locking ribs. Furthermore, although the container driver  32  shown in  FIG. 4  comprises two ledges  37  for abutment with the container driver locking means  25  only, other configurations having just one or three, four, or more ledges are also encompassed by the invention. 
         [0071]      FIG. 4  further shows plunger drive locking means  70 . Plunger drive locking means  70  is of generally cylindrical configuration (distal part  71 ) and comprises at its proximal end radial flange  72 . The proximal flange  72  of the plunger drive locking means  70  comprises at least one rotational lock element  73  projecting essentially radially. In the embodiment shown in the Figs, two such lock elements  73  are provided. With these rotational lock elements  73 , the plunger drive locking means  70  is initially rotationally locked to the container driver  32 . In order to provide such rotational locking, the container driver  32  comprises corresponding longitudinal ribs  75  at the inner surface of its distal part (shown in  FIG. 7 ). The rotational lock elements  73  initially abut against these ribs  75 . The axial length of these locking ribs  75  of the container driver  32  is adapted to the length the container driver  32  and the medical container holders  10  are displaced/displaceable to perform a needle penetration. In more detail, the axial length of the locking ribs  75  is such that upon full displacement of the medicament container holder towards the injection site, the rotational lock elements  73  are finally freed from engagement with the locking ribs  75 . This means that at this stage the plunger drive locking means  70  is no longer rotationally locked by the container driver  32 . In other words, when performing needle penetration, the container holder  32  is moved longitudinally relative to the plunger drive locking means  70 . The plunger drive locking means  70  is axially locked. Such axial lock is provided by a locking structure  76  at the distal end of the plunger drive locking means  70  which is in engagement with a corresponding structure at a distal end of the distal intermediate housing part  5  (see  FIG. 7 ). 
         [0072]      FIG. 5  shows further components of the injection device  1  according to the preferred embodiment. 
         [0073]    As mentioned above, needle  13  of medicament container  12  is covered by a rigid needle shield consisting of a soft part  14  and a rigid part  15 . 
         [0074]      FIG. 5  further shows plunger driver  50  which is rotationally locked to the plunger drive locking means  70  but slidable in axial direction in relation to plunger drive locking means  70 . This will be described in more detail in the context of  FIG. 6 . 
         [0075]    Plunger rod  60  shown in  FIG. 5  comprises a threaded structure  63  as well as at least one longitudinal groove  61 . At the proximal end, plunger rod  60  comprises a plunger rod tip  62  onto which a spinner element  65  is snap fit. Spinner element  65  acts on the stopper in the medicament container  12 . 
         [0076]    Finally,  FIG. 5  shows an indicator assembly for indicating end of dose, comprising am indicator  80 , and a U-bracket  81  arranged between the plunger rod  60  and the plunger driver  50 . The U-bracket  81  is connected to the plunger drive locking means  70  such that when the plunger rod  60  is proximally advanced and not in contact with the U-bracket, the U-bracket, the indicator  80  and the indicator rod  82  are forced distally.  FIG. 5  also shows indicator rod  82 , being also part of the indicator assembly. A spiral spring (not shown in  FIG. 5 ) is coaxially arranged on the indicator rod  82 , wherein the spiral spring is arranged within the plunger rod  60 . Thus, the indicator rod  82  with the spring is received within a central axial through hole in the plunger rod  60 , whereas U-bracket  81  lay with its two legs on the two opposing longitudinal grooves 90 degrees to the two opposing longitudinal grooves  61  of the plunger rod  60 . 
         [0077]      FIG. 6  shows plunger driver  50 . Plunger driver  50  comprises, in the shown embodiment, two internal longitudinal ribs  51 . These longitudinal ribs  51  interact with longitudinal grooves  61  on the outer surface of a plunger rod  60 . Thus, the plunger rod  60  is rotationally locked to plunger driver  50  but may axially slide along these ribs  51 . 
         [0078]    Plunger driver  50  further comprises a longitudinal slit  55  though its wall. With this longitudinal slit  55 , the plunger driver  50  is connected to the inner end of the first spring  40 . Thus, a force applied to the plunger driver  50  by the first spring  40  is transmitted to the plunger rod  60  due to the engagement of internal longitudinal ribs  51  into longitudinal grooves  61 . 
         [0079]    On the other hand, the plunger driver  50  comprises at least one external longitudinal rib  52 . In the embodiment shown, four such ribs are provided spaced at 90° to each other. The external longitudinal ribs  52  are slidably received in longitudinal grooves  74  of the plunger drive locking means  70 . Thus, as long as the plunger drive locking means  70  is prevented from being rotated due to the locking engagement with the container driver  32 , the plunger driver  50  and the plunger rod  60  are prevented from being rotated although the force of the first spring  40  acts on the plunger driver  50 . However, once the plunger drive locking means  70  is free to rotate, the plunger driver  50  and the plunger rod  60  also start to rotate, caused by the first spring  40 . In the initial stage of the injection device  1 , i.e. prior to its use, a proximal part of the plunger rod  60  is received in the central opening of the container driver  32 . As shown in  FIG. 6 , the central opening of container driver  32  comprises a threaded structure  38  that engages with the threads  63  of the plunger rod  60 . Thus, the threaded proximal section of the plunger rod  60  is screw threaded in the interior of the container driver  32 . Due to this threaded engagement, rotation of the plunger rod upon use of the injection device results in an axial displacement of the plunger rod towards the proximal end of the injection device. In other words, the plunger rod  60  is rotated by the thread engagement in the direction of the medicament container  12 , and causes the stopper (not shown) in the medicament container holder  12  and in abutment with spinner  65  to move towards the proximal end of the medicament container holder in order to expel medicament. The torque force of spring  40  will continue to drive the plunger rod towards the proximal end of the injection device  1  pressing the stopper to expel medicament through the needle  13 . The container driver  32  slides over along the plunger rod  60  as the plunger rod continues to move towards the proximal end of the device. The injection is completed when the stopper is at the proximal end of the medicament container. 
         [0080]    When the plunger rod  60  is fully rotated towards the proximal end of injection device  1 , the two legs of the U-bracket  81  are no longer supported by the longitudinal grooves of the plunger rod  60 . Thus, the radial legs  86  at the proximal ends of the U-bracket can disengage the slits in the plunger driver  50 . The spiral spring (not shown) coaxially arranged with the indicator rod  82  causes indicator assembly to move distally until the indicator  80  contacts the distal front surface of the distal housing part  3 . This causes the distal protrusion of the indicator  80  to project through the indicator opening  83  provided in the centre of the distal wall of the distal housing part  3 . This provides a visible and tactile indication to the user that the complete dose has been expelled. 
         [0081]      FIG. 7  shows a sectional view of the injection device  1  according to the preferred embodiment of the present invention in the initial position. In particular,  FIG. 7  shows how the second spring  45  is located in the interior of the distal intermediate housing part  5 . The distal end  46  of the second spring  45  is in contact with the inner surface of the distal radial wall of the distal intermediate housing part  5 . Alternatively, it may be in contact with a ledge provided at the inside of the distal intermediate housing part, proximal to the distal radial wall of the distal intermediate housing part  5 . The proximal end  47  of the second spring  45 , on the other hand, abuts against a distal surface of the container driver  32 . 
         [0082]    The same cross-sectional view is shown in  FIG. 8 , however as a perspective view in order to provide a different view of the various components relative to each other and their inter-engagement. Furthermore, in  FIG. 8  the relative arrangement of the indicator  80 , U-bracket  81 , indicator rod  82 , and injector distal opening  83  can be seen. The indicator rod  82  substantially extends within a central bore of the plunger rod  60 . At the distal end of the injection device  1 , a distal part of the injector rod  82  extends beyond the distal end of the plunger rod  60 , and is received in an inner central bore of the indicator  80 . The indicator rod  82  comprises a circumferential flange  84  adjacent to its distal end. Seen in axial direction, between the circumferential flange  84  and the proximal surface of the indicator  80 , the intermediate part of the U-bracket  81  is located. As seen in  FIG. 5 , this intermediate part of U-bracket  81  comprises a throughhole through which the distal part of the indicator rod  82  extends. The two legs of the U-shaped bracket  81  extend in axial direction towards the proximal end of the plunger rod  60 . At its proximal ends, the two legs of the U-bracket  81  each comprise a radial leg  86 . This radial legs  86  project into corresponding radial openings in the plunger driver  50  (see  FIG. 5 ). 
         [0083]      FIG. 9  shows a perspective view of a second preferred embodiment of the present invention. The injection device  100  shown in  FIG. 9  is to a large extent identical to the injection device  1  according to the first preferred embodiment of the present invention. Same components are labelled with identical reference numerals. In the following, only the differences between the first and the second preferred embodiment will be explained in detail. 
         [0084]    As shown in  FIG. 9 , the injection device  100  is different from the injection device  1  with respect to the indicator assembly that is provided to show end of dose. The structure for needle penetration and medicament injection shown in  FIGS. 2 through 6  is also present in the injection device  100  of  FIGS. 9 to 12 . 
         [0085]    The second preferred embodiment shown in  FIG. 9  comprises an indicator assembly  180  provided at the distal end of the housing. That is, the indicator assembly is preferably located distal to the plunger drive means  50 ,  70 , and/or distal to the first energy accumulating member. The indicator assembly comprises a cap  180 , in the embodiment shown transparent and having at least one opening  181  into which solid panels  184  are placed. In the embodiment shown in the drawings, four opposite openings  181  are provided. The four openings  181  are opposite with respect to the center axis of the injection device, i.e., they are located diametric. Through the transparent cap  180 , the user can see a signalling element in the form of a rotatable element, such as a wheel or disk  182 , which is also shown in  FIG. 10 . 
         [0086]    As shown in  FIG. 11 , the rotatable disk  182  comprises a cylindrical proximal protrusion  188 , such as a wheel hub. By means of this wheel hub  188 , the rotatable disk  182  is connected to the distal end of the plunger driver  50 . Thus, upon rotation of the plunger driver  50  by the first spring  40 , also the rotatable disk  182  rotates. This can be seen by the user through the cap  180 . Thus, the user can readily see that the device works properly and that an injection is in progress. 
         [0087]    As also shown in  FIG. 12 , the rotatable disk  182  comprises a distal indication structure having a plurality of segments  190   a,  . . . ,  190   i,  . . . ,  190   n.  These segments  190  alternate with radial ribs  192 , i.e. are separated from each other by radial ribs. The ribs  192  project from the surface of the rotatable disk in at least distal direction and extend radially with respect to the radial center of the injection device. When the rotatable disk  182  rotates, the alternating structure of ribs and segments are shown through the cap  180  as they pass the panels  184 . In a preferred embodiment, the segments  190  and/or the ribs  192  constitute visual signalling members  190 ,  192 . For example, the segment  190  or rib  192  shown through the cap  180  in the initial stage of the injection device  100  contains a first indication element, whereas the segment  190  or rib  192  shown through the cap in the final position of the injection probably comprises a second, different indication element so that the user can easily distinguish the initial stage prior to injection from the final stage after injection of the medicament. For example, the segments  190  are coloured in different colours. Alternatively (not shown in the drawings), the angular widths of the segments may vary, for example from a very small width to a wide width in order to distinguish the initial position from the final position. 
         [0088]    Furthermore, these rotary injection indication mechanisms are arranged such that the progress of injection is shown through at least one opening provided at least in a distal end surface of the housing. 
         [0089]    A further information mechanism available to the user is an audio signalling member. It comprises protrusions or ledges  194 ,  FIG. 11 , on a proximally directed surface of the rotatable disk  182 . As seen in  FIG. 11 , the ledges are directed generally in the radial direction but may be arranged in other directions. These ledges  194  are intended to cooperate with flexible members  196  arranged on a distally directed end surface  198  of the distal housing part  3 ,  FIG. 12 . The flexible members  196  comprise at least one (two in the embodiment shown) arms  200  that extend generally in the same plane as the surface  198 , with free ends having distally inclined surfaces  202 , forming wedge-shaped distally directed protrusions. 
         [0090]    Thus, when the rotatable disk  182  is rotating during injection as described above, the ledges  194  on the rotatable disk  182  will come in contact with the inclined surfaces of the protrusions  202  of the arms  200 , thereby pressing the arms  200  in the proximal direction until the protrusions  202  are moved out of contact with the ledges  194 . This will cause the arms  200  to flex back quickly, whereby the protrusions  202  of the arms  200  will hit the proximally directed surface of the rotatable disk  180 , producing an audible sound. Thus during the rotation of the rotatable disk  182  the ledges  194  and arms  200  with their protrusions will cause sounds that are audible during the injection sequence until the rotatable disk stops at the end of the injection sequence. 
         [0091]    In order to further provide the user with information during the injection sequence, a tactile information member is arranged at the distal end of the device. It comprises a tactile signalling member  204 ,  FIG. 11 , having a generally tubular shape. On its inner surface it is arranged with longitudinally directed ledges  206  (two in the embodiment shown) positioned diametrically on opposite sides. These ledges  206  are arranged to be fitted into longitudinally extending grooves  208  in a centre tap or column  210  attached to the inner surface of the cap  180  and directed in the proximal direction, as seen in  FIG. 13 . 
         [0092]    Further the driver  204  is arranged with at least one distally extending protrusion  212  attached to its distally directed end surface. In the embodiment shown, there are two protrusions  212  on the driver  204 . Further, the cap  180  is arranged with corresponding number of passages  214 ,  FIG. 13 , through its end surface, positioned on the side of the column  210  of the cap  180 . The protrusions  212  of the driver  204  has such lengths that they will protrude through the passages  214  the cap  180  and a distance above the distally directed end surface of the cap  180  when the driver  204  is in its most distal position along the column  210  of the cap  180 . The column  210  of the cap  180  has a diameter somewhat less than the inner diameter of the driver  204 , whereby the driver is rotationally locked to the tap but may slide along the tap as will be explained. 
         [0093]    The outer surface of the driver is arranged with thread segments  216 , e.g. like spirally extending ledges. These cooperate with corresponding threads or spirally extending grooves  218 ,  FIG. 12 , on a central passage of the proximal protrusion  188  of the rotatable disk  182 . 
         [0094]    During the injection sequence, the rotatable disk is rotating continuously, as described above. On the other hand, the tactile signalling member is locked rotationally due to the longitudinal ledges  206  fitting into the grooves  208  of the cap  180 , which in turn is fixed in relation to the distal housing part  3 . The rotation of the rotatable disk  182  will thus cause its thread segments  218  to act on the thread segments  216  of the tactile signalling member  204 , whereby the tactile signalling member  204  will be diplaced linearly in the distal direction from an initial position,  FIG. 14   a . The linear movement will in turn cause the distally directed protrusions  212  of the tactile signalling member to extend through the passages  214  and protrude above the surface of the cap  180 ,  FIG. 14   b . Thus, when a patient or user during the injection sequence is holding a finger against the distally directed end surface of the cap  180 , he/she will feel the protrusions  212  rising up from the surface. 
         [0095]    Thereby a positive tactile feeling and thus information about the progress of the injection is obtained. In this context it is to be understood that the length of the protrusions as well as initial position of the driver in relation to the rotatable disk and the pitch of the thread segments may be altered in many ways in order to obtain the desired, predetermined end result. For example, the protrusions may be positioned just below the distal surface of the cap at the start of the injection sequence, whereby the protrusions will provide tactile information right from the start of the injection sequence. On the other hand, the configuration may be such that the protrusions extend through the distal surface of the cap only at the very end of the injection sequence, when the tactile signalling member has reached an end position, thereby providing tactile information that indicate end of injection sequence, i.e. that the device is safe to remove. Also, the pitch of thread of segments  216 ,  218  may be adapted to obtain a predetermined speed of displacement of the tactile signalling member during injection. It is also to be understood that the tactile information as well as the audible information and visual information may be used and provided simultaneously to the user when handling the device. 
         [0096]    While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. 
         [0097]    Furthermore, in the claims the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single unit may fulfil the functions of several features recited in the claims. The terms “essentially”, “about”, “approximately” and the like in connection with an attribute or a value particularly also define exactly the attribute or exactly the value, respectively. Any reference signs in the claims should not be construed as limiting the scope. 
         [0098]    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.