Patent Publication Number: US-2009234298-A1

Title: Injection device

Description:
FIELD OF THE INVENTION 
     The present invention relates to an injection device of the type that receives a syringe, extends it, discharges its contents and then retracts it automatically. 
     BACKGROUND OF THE INVENTION 
     Previously known injection devices are shown in WO 95135126 and EP-A-0 516 473 and tend to employ a drive spring and a trigger that, when activated, causes the drive spring to act on the syringe when a releasable locking mechanism is also engaged. 
     The trigger acts is rotatable about an axis so that when it is depressed at a first end, a second end (which normally engages with the drive spring) is also rotated, thereby releasing the drive spring, extending the syringe and discharging its contents. The trigger is generally mounted in the side of the housing of the injection device parallel to the longitudinal axis of the body of the injection device. The trigger is rotated by pressing down on the trigger at one end in a direction towards the housing. 
     A problem with such devices is that the action of pressing down on the trigger towards the housing can be difficult if the device is being held in one hand. This poses significant problems for sick and ill users of the injection device, for example users suffering from rheumatoid arthritis. 
     SUMMARY OF THE INVENTION 
     The injection device of the present invention is designed to deal with this and other problems. 
     In view of the foregoing and in accordance with a first aspect of the invention, there is provided an injection device comprising:
         a housing defining a first axis, and being adapted to receive a syringe having a discharge nozzle, so that the syringe is movable between a retracted position in which the discharge nozzle is contained within the housing and an extended position in which the discharge nozzle extends from the housing through an exit aperture;   a drive that is acted upon and in turn acts upon the syringe; and   a trigger rotatable from a rest position, in which it causes the drive to be retained, to an active position, in which it no longer causes the drive to be so retained, thus allowing the contents of the syringe to be discharged through the discharge nozzle,   wherein the trigger is pivotally mounted and has a surface shaped such that a user can apply a force in a direction substantially parallel to the first axis to rotate the trigger from its rest position to its active position.       

     By having the trigger operable so that a force can be applied in a direction which is substantially parallel to the first axis, the trigger does not need to be pushed into the side of the housing to activate it. This way, the injection device can be held and operated with one hand by sliding the hand down the housing and over the trigger as the exit aperture is pushed against a user&#39;s body. 
     Preferably, the surface is a first concave surface. 
     In one embodiment of the invention, the surface is provided with a plurality of ridges. 
     Preferably, the housing is provided with a second concave surface substantially opposite to the trigger so that a user can grip the device and apply a force to the trigger and second concave surface in a direction substantially parallel to the first axis. 
     In one embodiment of the invention, the housing comprises an abutment located adjacent the trigger between the trigger and the exit aperture. 
     In one embodiment of the invention, the second concave surface is provided with a plurality of ridges. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  shows a perspective view of an injection device according to the present invention; 
         FIG. 2  shows an alternative perspective view of an injection device according to the present invention; and 
         FIG. 3  shows a side view of the injection device of  FIGS. 1 and 2  with an upper section of the housing of the injection device removed. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIGS. 1 to 3  show an injection device  110  according to a first embodiment of the present invention. The injection device  110  has an injection device housing  112  and a longitudinal axis  101 . 
     A syringe (not shown) is contained in the housing  112 . The injection device  110  comprises trigger  114  and a releasable locking mechanism  116 . The trigger  114  has a first end  114   a  and a second end  114   b . The trigger  114  is rotatable about a pivot  115  from a rest position to an active position. The second end  114   b  of the trigger  114  connects with a drive coupling  121  which is acted upon by a drive spring  120 . The drive coupling  121  is in communication with the syringe. 
     Rotation of the trigger  114  about the pivot  115  in a direction R (i.e. downwards into the housing  112  at its first end  114   a ) causes the second end  114   b  of the trigger  114  to disengage from the drive coupling  121 , thereby letting the drive spring  120  drive the syringe (via the drive coupling  121 ) along the longitudinal axis  101  and out of an aperture  118  in the housing  112 . 
     The releasable locking mechanism  116  is in communication with sliding sleeve  126  which protrudes, when in a first position, from the aperture  118  in the housing  112 . The locking mechanism  116  is deactivated by movement of the sliding sleeve  126  along the longitudinal axis  101  into the housing  112  into a second position. 
     A first end  126   a  of the sliding sleeve  126  can be placed against a body into which drug is being delivered, thereby deactivating the releasable locking mechanism  116  and allowing the trigger  114  to rotate in direction R from its rest position to its active position. 
     The trigger  114  is shaped in such a way that there is a section of surface  201  at an angle to the longitudinal axis  101  of the injection device  110 . Hence, rotation of the trigger  114  can take place by exertion of force in a direction which is not necessarily perpendicular to the longitudinal axis. This way, a rotational force can still be exerted on the trigger  114 , even if that force is not applied inwards towards the housing  112 . 
     In the embodiment of the invention shown in  FIGS. 1 and 3 , the surface  201  is shaped concavely. 
     The hand of a user of the injection device  110  can be wrapped around the housing  112  and the injection device  110  forced against the user&#39;s body so that the sliding sleeve  126  causes the locking mechanism  116  to disengage. The trigger  114  can now be activated by movement of the user&#39;s hand across the housing  112  and over the trigger  114  so that a force having a component in the direction of the longitudinal axis  101  is applied to the trigger  114  causing it to rotate. 
     The housing  112  also comprises a ridge  210  (or an abutment) located behind the trigger  114  towards the exit aperture  118  of the housing  112 . The ridge acts as a stop surface to prevent a user&#39;s hand moving further down the housing  112  once the trigger  114  has been activated. This way, the injection device  110  can be held firmly against a user&#39;s body after activation of the trigger  114  and whilst the contents of the syringe is being dispelled into their body. 
     The housing  112  comprises a second concave surface  202  located substantially opposite to the trigger  114 . Thus, the user&#39;s hand is prevented from moving further down the housing  112  once the trigger  114  has been activated. 
     The surface  201  and a section of the surface of the housing opposite the trigger  114  both comprise ridges  204  which act as grips for the user&#39;s hand. 
     It will of course be understood that the present invention has been described above purely by way of example and modifications of detail can be made within the scope of the invention.