Abstract:
The present invention relates to an injection device, comprising a housing ( 10 ) including a container carrier ( 16 ) having a medicament container ( 18 ) and a needle ( 22 ) attached to the medicament container, a needle shield ( 12 ), means for initiating a penetration; penetration means for automatic penetration of needle, means for automatically injecting medicament, means for an automatically withdrawing the needle. The invention is characterized in an active triggering withdrawal mechanism capable of allowing the means for automatically withdrawing the needle to be triggered when the injection device starts to be removed from an injection site.

Description:
TECHNICAL FIELD 
     The present invention relates to an injector and in particular to an injector having several automatic functions as automatic penetration, automatic injection and automatic active triggering withdrawal. 
     BACKGROUND 
     There are many injectors on the market where the aim is to have high degrees of functionality and automatic features, such as in connection with penetration, injection, setting of dose, priming and covering of the needle after use. At the same time there is a demand on robustness, repeatability and reliability regarding the function, which sometimes might be difficult to meet when dealing with complex multi functions involving many interacting components. When there further are demands on low production costs, especially for devices that are to be used only once, the picture becomes even more complex. 
     There are in the patent literature numerous solutions to injection devices, the bulk of which never enter the market due to that they do not meet the demands in one way or the other. There is therefore a continuous search for solutions that provide the desired functions that at the same time fulfill the functional and/or economical demands. 
     Many devices having multi-functions that work in sequence, such as for example penetration, followed by injection, followed by withdrawal, have a subsequent sequence triggered at the end of a previous sequence, for example when the needle has reached full penetration depth, the injection sequence is triggered. 
     Safety margins have been implemented in the devices having multi-functions that work in sequence in order to ensure that each sequence is effective, e.g., in WO-A1-2006057604. Mostly the safety margins are overestimated in the devices, leading to medicament spill after the needle withdrawal, which also results in inaccurate delivered doses. 
     In EP-A-0 516 473, a retraction mechanism has been proposed wherein, at the point at which a plunger rod reaches the end of a bore in a syringe, a portion of a coupling instantaneously collapses in length as a retraction spring retracts a needle. This proposal suffers the problem that, due to the tolerances of the various components, it cannot be assured that the retraction mechanism will enable retraction of the needle at precisely the moment at which the plunger rod reaches the end of the bore. Therefore, either the mechanism retracts the needle before the plunger rod reaches the end of the bore, such that the syringe is not emptied, or the plunger rod reaches the end of the bore before the mechanism has moved sufficiently far to retract. 
     Although this problem has been recognized in U.S. Pat. No. 6,159,181 and EP-B1-0 996 473, the proposed solutions have been to provide a user actuated withdrawal mechanism rather than an automatic one and this is considered to be undesirable due to the risk of removing the injector from the injection site before the user actuated withdrawal mechanism has been activated. Then there exists the dangers of having an extended and possibly contaminated needle exposed around the user. 
     It is an object of the present invention to provide an injection device having an active triggering withdrawal mechanism, which is relatively simple and of low cost and which overcomes or at least reduces the problems identified above. 
     SUMMARY 
     The present invention provides an injector that fulfils the demands that are put on such devices regarding functionality, reliability, and low cost. 
     In accordance with the invention, an injection device comprises a housing including a container carrier having a medicament container and a needle attached to the medicament container, a needle shield slidable arranged inside said housing with a contact part intended to be applied against an injection site, activation means arranged to be interactively connected to said needle shield and capable of, upon manual activation, initiating a penetration sequence; penetration means interactively connected to said activation means and capable of performing an automatic penetration of the needle, injection means interactively connected to said penetration means and capable of triggering and performing an automatic injection of the medicament, withdrawing means interactively connected to said injection means and capable of triggering and performing an automatic withdrawing of the needle, wherein said device further comprises an active triggering withdrawal mechanism interactively connected to said withdrawing means and capable of allowing said withdrawing means to be triggered when the injection device starts to be removed from the injection site. 
     The active triggering withdrawal allows the user to have control over when to withdraw the needle, preventing incomplete dosages due to early withdrawal and/or malfunctions in an automatic needle-retraction device. 
     The injection device is a cost-effective multi-function device that operates with a safe and reliable chain of sequences, thus ensuring that the user receives a proper accurate dose of medicament each time the device is used. 
     These and other features and advantages of the present invention will become apparent from the following detailed description and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following detailed description, reference is made to the drawings, of which: 
         FIG. 1  is a longitudinal cross-section of an embodiment of the present invention, 
         FIGS. 2-3  are exploded views of the injector of  FIG. 1 , 
         FIGS. 4-11  show different functional steps of the device of  FIG. 1 , 
         FIG. 12   a, b  show detailed views of a second embodiment of the present invention, and 
         FIG. 13-15  show different functional steps of the device of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
     The device according to the figures comprises a generally tubular housing  10 . In the front end of the housing, to the right in  FIG. 1 , a generally tubular needle shield  12  with a contact part intended to be applied against an injection site is slidable arranged in the housing. When the device is unarmed, the needle shield is held in place by protrusions  14  on its outer surface co-operating with ledges  15  on the inner surface of the housing. 
     Inside the needle shield in the front area of the device a container carrier  16  is arranged. Inside the container carrier a container  18 , containing medicament, is arranged. The container is prevented from moving forward by a circumferential ledge. The front end of the container can be arranged with attachment means for attaching a needle  22  to the container,  FIG. 6   a . The rear end of the container is seated with a flange  24  adjacent the container carrier  16 . 
     The device comprises activation means arranged to be interactively connected to said needle shield and capable of, upon manual activation, initiating a penetration sequence as it will be explained in detail below. The activation means comprises flexible arms  62  having inwardly extending ledges  66  on a penetration sleeve  50 , recesses  60  on the lock-out sleeve  58 , a circumferential groove  68  on an activation housing  34 , and an activation button  72  having inwardly extending parts  74  facing the arms  62 . 
     Further, the device comprises penetration means interactively connected to the activation means and capable of performing an automatic penetration of the needle as it will be explained in detail below. The penetration means comprises tongues  26  arranged on an activation housing  34  and snap-fitted to the container carrier  16 , outwardly extending protrusions arranged on flexible arms  44  which are arranged on said activation housing; a retraction release ring  46  abutting said outwardly extending protrusions, and a penetration spring  48  arranged between the retraction release ring  46  and an inner rear wall of a penetration sleeve  50 . 
     The device also comprises injection means interactively connected to the penetration means and capable of triggering and performing an automatic injection of the medicament as it will be explained in detail below. The injection means comprises flexible tongues  36  arranged on the activation housing  34  and where each tongue is arranged with inwardly directed ledges  35 ; a plunger rod  30  having a circumferential groove  37  where the ledges  35  are positioned when the device is unarmed; and an injection spring  38  arranged between a front wall  40  of the plunger rod and a rear wall  42  of the activation housing. 
     Further, the device comprises withdrawing means interactively connected to the injection means and capable of triggering and performing an automatic withdrawing the needle as it will be explained in detail below. The withdrawing means comprises a penetration retraction spring  76  arranged between the retraction release ring  46  and protrusions  78  arranged on an activation housing  34 ; and the flexible arms  44  arranged on said activation housing. 
     The plunger rod  30  extends into the container with one end adjacent a stopper  32  arranged within the container. The rear end of the plunger rod is surrounded by the activation housing  34  which is snap-fitted to the container carrier  16  by tongues  26  of said activation housing. The activation housing is arranged with flexible tongues  36 , where each tongue is arranged with inwardly directed ledges  35 . In the initial state, these ledges are positioned in a circumferential groove  37  on the plunger rod  30 . The tongues and ledges are held in this position by the injection release ring  28 . 
     Inside the plunger rod, the injection spring  38  is arranged compressed between a front wall  40  of the plunger rod  30  and a rear wall of the activation housing  34 . The activation housing is further arranged with outwardly extending protrusions arranged on flexible arms  44 . Abutting the protrusions is the retraction release ring  46 , which will be described in more detail below. 
     The penetration spring  48 , is arranged between the retraction release ring  46  and an inner rear wall of the penetration sleeve  50 . At the front end of the penetration sleeve, a retraction spring retainer  52  is snap fitted with the penetration sleeve  50  by outwardly directed protrusions  54  having a straight part and a ramped part, extending into recesses  56  of the penetration sleeve. Outside the penetration sleeve is arranged the lockout sleeve  58 . At the rear part of the lockout sleeve  58 , tongues with recesses  60  are arranged adjacent flexible arms  62  of the penetration sleeve, which arms are arranged with outwardly extending protrusions  64  as well as inwardly extending ledges  66 . In the initial position these ledges are in contact with a wall of a circumferential groove  68  on the activation housing  34 . The upper part of the arms is further arranged with inclined surfaces  70 . 
     At the upper end of the housing an activation button  72  is slidably arranged, having inwardly extending parts  74 , which are arranged with inclined surfaces facing the inclined surfaces  70  of the arms  62 . Since the tongues with recesses  60  are arranged adjacent the flexible arms  62 , the arms  62  cannot be moved radially outwards and consequently blocks the activation button to be moved. Further a penetration retraction spring  76  is arranged between the retraction release ring  46  and protrusions  78  arranged on the activation housing  34 ,  FIG. 2 . 
     The device is intended to function as follows. In the initial position or when the device is unarmed, the needle shield  12  is positioned inside the housing  10  and held in place by the protrusions  14  acting against the ledge of the housing,  FIG. 1 . The device may be delivered with a protective cap  80  inserted into the front end of the needle shield surrounding the front end of the container  18  with its syringe cap. The protective cap is removed, whereby the syringe cap is also removed, and a needle  22  is attached to the container. The needle shield  12  is then pushed manually forward until the protrusions  14  of the needle shield enter a recess  82  on the inner surface of the housing  10  for arming the injection device,  FIG. 4   a . The protrusions have such a configuration that they are able to slide over the ledge when the needle shield is extended but prevent a pushing in of the needle shield when they have entered the recess. When in the outermost position, the needle shield is connected to the lock-out sleeve by snap-in members connecting to cut-outs (not shown). The needle shield is now movably connected to the lock-out sleeve  58 . 
     The device is now ready to use. In order to initiate a penetration sequence, the user places the front end of the needle shield  12  against an injection site wherein the pressing of the needle shield  12  causes it to move a short distance inwards until the protrusions  14  of the needle shield abut the upper wall of the recess  80 ,  FIG. 5   a . This movement causes the lockout sleeve  58  to be moved the same short distance because of the connection between the needle shield  12  and the lockout sleeve  58 . 
     If the device is lifted or removed from the injection site the lockout sleeve and the needle shield are resiliently moved back to the initial position due to the interaction between the tongues of the lock out sleeve  58  and inclined surfaces of the penetration sleeve  50 . 
     The movement of the lockout sleeve causes the recesses  60  to be positioned outside of the outwardly extending protrusions  64  of the arms  62  of the penetration sleeve  50 ,  FIG. 5   b , which enables the button  72  to be depressed whereby the inclined surfaces of the inwardly extending parts act on the inclined surfaces  70  of the arms  62 , causing them to move radially outwards. This is not possible when the lockout sleeve  58  has not been moved since the protrusions of the arms then abut the inner surface of the lockout sleeve. 
     When the arms move radially outwards, the inwardly directed ledges  66  of the arms  62  are moved out of contact with the circumferential groove  68  of the activation housing  34 ,  FIG. 6   b , which then is moved forward by the penetration spring  48  acting on the retraction release ring  46  which is held in place relative the activation housing  34  by the protrusions of the flexible arms  44 ,  FIG. 7 . Thus both the activation housing  34 , the plunger rod  30  arranged inside the activation housing, the container carrier  16  connected to the activation housing, the injection release ring  28  and the syringe  18  are moved forward causing a penetration of the needle into the injection site. 
     At a certain depth the injection release ring  28  is stopped by the engagement of protrusions on its flexible arms into slots on the shield, which frees the flexible tongues  36  because they pass the ring due to the continued movement of the activation housing  34 . The freeing of the tongues cause them to flex outwards radially and lock in pockets, whereby the inwardly directed ledges are moved out of contact with the groove  38  on the plunger rod  30  and the movement of the activation housing  34 , and thus the penetration, is stopped when the front end of the container carrier  16  abuts tongues  92  of the needle shield,  FIG. 8 . 
     The releasing of the inwardly directed ledges from the groove  38  on the plunger rod  30  triggers an injection by releasing the plunger rod due to the force of the injection spring  38 , whereby it pushes on the stopper  32  and an injection is performed,  FIG. 9 . When the injection has been completed and/or an indication has been given to the user as e.g. a sound or the active looking at a window showing that the injection has been completed; the user removes the device from the injection site by lifting the injection device up and away from the injection site, hereafter called an active triggering withdrawal. 
     The active triggering withdrawal is performed by an active triggering withdrawal mechanism which comprises means as tongues  92  arranged on the inner surface of the needle shield,  FIG. 8   a ; and the penetration spring  48 . Said penetration spring  48  is used for urging the medicament container carrier with the container and needle forward during the penetration sequence until the front edge of the container carrier  16  contacts the tongues  92 . When the injector is lifted or removed from the injection site, the penetration spring  48  causes the container carrier  16  and thus the needle shield  12 , because of the above mentioned connection, to move forward a certain distance. The forward movement of the container carrier also causes the plunger rod  30  to move forward in relation to the activation housing  34 . The upper edge of the plunger rod will then pass the outwardly directed protrusions of the flexible arms  44  holding the retraction release ring,  FIG. 10 . This will in turn allow said flexible arms  44  to move inwards, which in turn frees the retraction release ring  46  and thereby triggering the withdrawal sequence. The retraction spring  76  is now free to expand whereby the container carrier together with the injection needle is drawn into the housing of the injector by the force of the retraction spring  76  acting on the protrusions  78  of the activation housing  34 . The needle is now protected inside the needle shield  12 ,  FIG. 11 . 
       FIGS. 12-15  disclose a second embodiment of the present invention where the same components as for the previous embodiment have the same reference numerals. Further, this embodiment has the same components and function regarding penetration and injection and these steps will therefore not be described in detail. The active triggering withdrawal mechanism comprises in this embodiment means as grooves  104  of e.g. a lock plate  100  surrounding the activation housing  34 . The grooves  104  have a certain shape such that they are adapted to cooperate with corresponding ledges  106  of the protrusions of the flexible arms  44 . 
     This embodiment is intended to function as follows. The penetration and injection are performed in the same manner as described above. However, when the penetration spring  48  urges the activation housing, the medicament container carrier with the container and the needle forward during the penetration sequence; the ledges  106  comes into engagement with the grooves  104  for preventing the flexible arms  44  from being moved inwards  FIGS. 12 and 13 . Further, when the injector is removed or lifted from the injection site, the lock-out sleeve  58  and thus the needle shield are moved forward a certain distance due to the interaction between the tongues of the lock out sleeve  58  and inclined surfaces of the penetration sleeve  50 . The front surface  110  of the lock-out sleeve  58  comes in contact with the lock plate and the movement causes the lock plate to move forward such that the ledges  106  comes out of contact with the grooves  104 ,  FIG. 14 . This in turn enables the flexible arms  44  to collapsing inwards. 
     The collapsing causes the retraction release ring  46  to pass the protrusions of the flexible arms  44  triggering the withdrawing of the needle, and the container carrier together with the injection needle is drawn into the housing of the injector by the force of the retraction spring  76  acting on the protrusions  78  of the activation housing  34 . The needle is now protected inside the needle shield  12 . 
     It will be understood that the embodiments described above and shown in the drawings are to be regarded only as non-limiting examples of the invention and that they may be modified within the scope of the patent claims.