Medicament delivery device

#The invention relates to medicament delivery devices. More particularly, it relates to an injection device, such as an auto-injector, for injecting a fluid medicament, wherein after the medicament has been delivered, a needle protecting sleeve associated with the injection device is moved or slid to cover the injection needle.

#Moving or sliding a needle protecting sleeve in a proximal direction, from a distal position in which the needle is exposed, by using a spring, such that the needle is covered and protected against being accessed, is known from WO2002047746A1. The spring which forces the needle protecting sleeve to move or slide over the injection needle is pre-tensioned by an amount. When the needle protecting sleeve is moved or slid beyond the injection needle, the spring force decreases according to the rules of Hooke's Law. Thus, the spring has to be pre-tensioned such that the needle protecting sleeve can reliably assume an end position in which it fully covers the injection needle. However, a problem is that having a device with pre-tensioned springs acting on plastic components in storage for long periods of time may deform the plastic components. Also, having a device that is triggered or partially triggered by shifting the needle protecting sleeve from a proximal position into a distal position the spring is further tensioned by a further amount. A further problem is to obtain a balance of forces since it is desirable that the force needed to shift the needle protecting sleeve in the distal direction is low, to make it easier for the user to handle the device and on the other hand, an increased spring force is desirable for shifting the needle protecting sleeve in the proximal direction from the distal position.

#In order to overcome one or several of the above-mentioned problems, an injection device according to claim 1 is provided.

#In the detailed description of the invention, reference will be made to the accompanying drawings, of which

#FIG. 1 is a perspective view of a medicament delivery device according to an embodiment of the invention,

#FIG. 2 is cross-sectional view of a proximal part of the device of FIG. 1 in an initial state,

#With regard to fastening, mounting, attaching or connecting components of the present invention, unless specifically described as otherwise, conventional mechanical fasteners and methods may be used. Other appropriate fastening or attachment methods include adhesives, welding and soldering. Generally, unless otherwise indicated, the materials for making embodiments of the invention and/or components thereof may be selected from appropriate materials such as metal, metallic alloys, ceramics, plastics, etc.

#FIG. 1 shows an injection device having a longitudinal axis L and which is embodied as an auto-injector. The injection device comprises a housing 1 which is formed from a proximal housing part 3 and a distal housing part 4. The proximal housing part 3 is axially fixed to the distal housing part 4 and cannot be easily disassembled by the user. Configuring the injection device in two parts has the advantage that easier assembly of the various components is possible during manufacturing of the device. FIG. 2 shows the injection device further comprising a container holder 20 which accommodates a medicament container 10. The medicament container comprises a container vessel normally made of glass and having an injection needle 11 at the proximal end and a distal movable stopper/piston 12 at the distal end of the container vessel. The container holder 20 is arranged within the housing such that it is longitudinally movable relative to the housing towards the proximal end of the device from a non-delivery position into a delivery position. The medicament container can typically be arranged with or without a flange at its distal end. The medicament container may also comprise a Rigid Needle Shield (RNS) or a Flexible Needle Shield (FNS). Thus, the container holder can be configured to receive a medicament container having either an RNS or an FNS and to hold the medicament container by the flange, by the front part or to hold it by both the flange and the front part. These configurations are well known in the art.

#The injection device further comprises a drive mechanism, arranged in the distal housing part. The drive mechanism can be configured to achieve an auto-penetration and auto-injection by using at least one spring. By using two springs, a penetration spring is used for forcing the container holder towards the proximal end of the device and thereby achieving an auto-penetration of the needle. An injection spring is used for forcing a plunger rod towards the proximal end of the device to thereby achieve an auto-injection i.e. an auto delivery of medicament through the needle. Alternatively a single spring may be used to control both the auto-penetration and the auto-injection. Moreover, the drive mechanism is normally configured to hold the spring or springs in a pre-tensioned state. These kinds of drive mechanisms are well known in the art. In this respect it is to be understood that a number of different drive mechanisms can be incorporated in the present invention. The drive mechanism can be of the type disclosed in WO2002047746A1 and in the Swedish patent application SE1150788-6. To the extent not inconsistent with this disclosure, the disclosures of WO2002047746A1 and of the Swedish patent application 1150788-6 are incorporated herein by reference.