Patent Description:
Many injectors on the market, especially pen-injectors, are provided with a functionality to allow multiple doses to be given from a medicament container. In many instances the dose quantity is fixed and is set just before a dose is to be delivered. Thus, a manual dose setting sequence is first performed and then a manual dose delivery sequence is performed.

Document <CIT> discloses an assembly for a drug delivery device comprising a first threaded member a second threaded member with a longitudinal axis and a thread, having at least two consecutive portions with different leads and a drug delivery device for setting and dispensing a number of user variable doses of a medicament comprising such an assembly.

Document <CIT> discloses a handheld injection device comprising a housing, a dose indicator and axially constrained and rotatable with respect to the housing during dose setting and during dose dispensing. A gauge element is at least partly interposed between the housing and the dose indicator. The gauge element (<NUM>; <NUM>) is axially guided within the housing (<NUM>; <NUM>) and in threaded engagement with the dose indicator at rotation of the dose indicator causes an axial displacement of the gauge element.

Document <CIT> discloses a pen-type injector comprising a housing, a cartridge being retained within the housing, means for selecting a dose of medicinal product to be expelled and means for expelling the selected dose of medicinal product The housing comprises a unitary housing within which the dose selecting means and the dose expelling means are moveably retained.

Document <CIT> discloses a clicker arrangement for use in a drug delivery device and a drug delivery device comprising such a clicker arrangement. The arrangement comprises a first, rotatable element and a second, non-rotatable element. Upon relative rotation of the first element and the second element. a clicker arm is elastically deflectable by a cam and relaxable upon disengagement with the cam thereby generating an audible and/or tactile feedback signal.

Document <CIT> discloses such a medicament delivery device having a dose setting member that is turned. The dose setting member is connected to a dose indicator barrel having a set of numerals that are visible through a window in a housing part. A nut member provided with a thread segment is arranged between the dose setting member and an internal thread on the housing. The length of the internal thread corresponds to the length that the piston rod has to travel in order to empty the medicament container and a stop on the thread segment engages an end wall of the internal thread when the medicament container is empty which thereby prevents the user for setting a dose larger than the remaining content of the medicament container.

The aim of the present invention is to provide a reliable and simple solution of preventing setting of doses of medicament that are larger than the remaining quantity of a medicament container.

This aim is solved with a drive mechanism comprising the features of the independent patent claim. Preferable embodiments of the invention form the subject of the dependent patent claims.

As stated above, the activator sleeve rotates somewhat also during dose delivery, i.e. when the actuator is manually pressed in the proximal direction. The rotation of the activator sleeve has the feature of locking the activator in a depressed state after completed dose delivery. Because of this, the activator sleeve may comprise protrusions arranged to interact with the actuator such that activator sleeve is rotated when the actuator is operated. The protrusions of the activator sleeve then cooperate with ledges of the actuator, which ledges are arranged inclined in relation to the longitudinal direction.

As stated above, the actuator is locked after dose delivery and this is performed in that the actuator is arranged with locking elements arranged to cooperate with the protrusions of the activator sleeve such as to lock the actuator after operation for delivering a dose of medicament. The locking elements may comprise ledges arranged generally transversal to said longitudinal direction. The locking elements may also comprise ramped or wedge-shaped sections on which the protrusions of the activator sleeve may slide before coming in contact with the generally transversal ledges.

In order to provide a subsequent operation of the actuation mechanism, the transversal ledges may be interconnected with the inclined ledges such that turning of the activator sleeve moves the protrusions from a locking position to a release position of the actuator. According to a further aspect, the actuation mechanism may further comprise a drive member acting on the actuator for urging it in a distal direction of the actuation mechanism when the actuator is released.

In addition, the actuation mechanism may further comprise a toggle sleeve operably arranged between the actuator and the plunger rod for urging the plunger rod in a proximal direction during operation of the actuator. In this respect, the plunger rod may be arranged with threads, a driver non-rotatably connected to the plunger rod, which driver is arranged with protrusions on its outer surface, that the toggle sleeve is arranged with surfaces inclined in relation to the longitudinal direction, causing a rotation of the plunger rod when the actuator and the toggle sleeve are moved in the proximal direction.

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.

In the embodiment shown in the drawings, the medicament delivery device comprises a generally tubular distal housing part <NUM> and a generally tubular proximal housing part <NUM>. In this regard it is to be understood that the housing may comprise a number of different sub-parts depending on manufacturing and assembly aspects.

The proximal end of the distal housing part is arranged with attachment elements such that proximal housing part <NUM> can be attached. Thereby the distal end of the proximal housing part <NUM> is arranged with a central passage having a diameter generally corresponding to the diameter of the proximal end of the distal housing part <NUM> and provided with corresponding attachment elements. In this regard it is to be understood that the attachment elements may have a number of different shapes and functions for attaching the medicament container holder to the housing, such as threads, bayonet couplings, snap-in protrusions etc., if the proximal housing part <NUM> is to be releasibly attached to the distal housing part <NUM>. If the proximal housing part <NUM> is to be permanently attached, the attachment elements may comprise wedge-shaped grip protrusions and recesses that allow assembly but prevent disassembly, welding, glue, etc. A protective cap <NUM> is also provided for releasably covering the proximal housing part <NUM>.

The proximal housing part <NUM> is designed as a medicament container holder and is arranged to house a generally tubular elongated medicament container <NUM>, which is provided with a resilient movable stopper <NUM>. The proximal housing part <NUM> may be transparent or may be provided with openings or windows so that the medicament container <NUM> and its content may be viewed. The proximal end of the medicament container <NUM> is provided with a neck portion <NUM> arranged with a penetrable septum <NUM>, <FIG>. The neck portion <NUM> is arranged to fit into a neck portion <NUM> of the proximal housing part <NUM>. The neck portion <NUM> of the proximal housing part <NUM> is provided with attachment elements for a medicament delivery member that may be an injection needle provided with a hub having corresponding attachment elements. In this regard the attachment elements may be threads, bayonet couplings, snap-in attachments, luer-connections, just to mention a few options. Further, a generally ring-shaped medicament container fastener <NUM> is arranged to abut a distally directed surface of a medicament container <NUM> placed in the proximal housing part <NUM> with a proximally directed surface. The medicament container fastener <NUM> is urged in the proximal direction by a compression spring <NUM> arranged between the medicament container fastener <NUM> and a proximally directed surface of an end wall <NUM> of the distal housing part <NUM>. The movement in the proximal direction of the medicament container fastener <NUM> is limited by radially outwardly directed protrusions <NUM> on an outer surface of the medicament container fastener <NUM> cooperating with cut-outs <NUM> of proximally directed ledges <NUM> on the proximally directed surface of the end wall <NUM>, <FIG>.

The medicament delivery device further comprises an actuation mechanism <NUM>, <FIG> and <FIG>. The actuation mechanism <NUM> comprises an elongated plunger rod <NUM>, <FIG> and <FIG>, provided with threads <NUM> on its outer surface, which threads <NUM> are arranged to cooperate with corresponding thread segments <NUM> in a central passage <NUM> in the proximal end wall <NUM> of the distal housing part <NUM>, <FIG>. The plunger rod <NUM> is arranged with two longitudinally cut-away sections <NUM>, on opposite sides of the plunger rod <NUM>, forming support surfaces. The plunger rod <NUM> is arranged to fit into a generally tubular driver <NUM>. The inner surface of the driver <NUM> is arranged with two sets of longitudinally extending ledges <NUM> wherein the plunger rod <NUM> fits into the space <NUM> between these sets of ledges <NUM> such that the support surfaces of the cut-away sections <NUM> of the plunger rod <NUM> will be in contact with side surfaces of the ledges <NUM>, whereby the plunger rod <NUM> is rotationally locked to the driver <NUM> but linearly movable in the longitudinal direction. The proximal end of the driver <NUM> is provided with ramped surfaces <NUM> that end in ledges <NUM>, which ledges <NUM> interact with ledges <NUM> on ramped surfaces <NUM> on a distally directed surface of the end wall <NUM> of the distal housing part <NUM> surrounding the threaded central passage <NUM>.

The outer surface of the driver <NUM> is further arranged with two outwardly directed protrusions <NUM> arranged on opposite sides of the driver <NUM>, <FIG>. These protrusions <NUM> are arranged to interact with edge surfaces <NUM> of cut-outs <NUM> at a proximal part of a generally tubular toggle sleeve <NUM>, which is positioned coaxial and outside the driver <NUM>. The edge surfaces <NUM> of the toggle sleeve <NUM> have a certain configuration as seen in <FIG>, having a first section <NUM>I with an inclination alpha. The first section <NUM>I is then interrupted by a second section <NUM>II with a very steep inclination beta and in an opposite direction as the first section <NUM>I. The second section <NUM>II then ends in a further first section <NUM>I. The first and second sections are arranged twice around the proximal end of the toggle sleeve <NUM>. The function of the protrusions <NUM> and the edge surfaces <NUM> will be described in detail below. The toggle sleeve <NUM> is further arranged with an end wall <NUM> at its distal end and wedge-shaped cut-outs <NUM> on a distal end area of the toggle sleeve <NUM>, the function of which will be described below. A compression spring <NUM>, hereafter named toggle sleeve spring, <FIG> and <FIG>, is arranged with a distal end in contact with a proximal surface of the end wall <NUM> of the toggle sleeve <NUM>, and with a proximal end in contact with distally directed surface of an annular flange <NUM> of a generally tubular washer <NUM>, <FIG>, wherein the washer body extends into the toggle sleeve spring <NUM>. A proximally directed surface of the flange <NUM> of the washer <NUM> is in contact with a distal end surface <NUM> of the driver <NUM>.

Coaxial with and outside of the toggle sleeve <NUM> is a generally tubular actuator <NUM>, <FIG>. The actuator <NUM> is arranged with a number of radially outwardly directed ledges <NUM> at a proximal part thereof, which ledges <NUM> are configured to fit in between pairs of longitudinally extending ledges <NUM>, <FIG>, on an inner surface of the distal housing part <NUM>, thereby creating a rotational lock between the actuator <NUM> and the distal housing part <NUM> but allowing axial movement of the actuator <NUM>. The actuator <NUM> is further arranged with a number of sets of ledges <NUM> on its outer surface, which ledges <NUM> have a certain extension as will be explained. A first section <NUM>I of the ledges is arranged facing the distal direction and with a steep inclination in relation to the longitudinal direction of the actuator <NUM>. At one end of the first section, a second section <NUM>II is arranged, extending in the circumferential direction. A third section <NUM>III is connected to the second section <NUM>II, extending with an inclination in relation to the longitudinal direction L. Parallel to the third section <NUM>III, a fourth section <NUM>IV is placed, thus having an inclination in relation to the longitudinal direction L.

A fifth section 90v then connects to the third section <NUM>III, extending in the circumferential direction. The fifth section 90v then connects to a sixth section <NUM>VI extending in the longitudinal direction. The sixth section <NUM>VI then connects to a seventh section <NUM>VII extending in the circumferential direction, which in turn connects to the first section of a subsequent set of sections <NUM>. An area between the fourth section <NUM>IV and the sixth section <NUM>VI is arranged as a wedge-shaped ramp <NUM> having a distally directed ledge <NUM>. The sets of ledges are repeated two times around the circumference of the actuator <NUM>. Distally of the ledges <NUM> are a number of longitudinally extending ledges <NUM>. The distal end part <NUM> of the actuator <NUM> is arranged with a somewhat dome-shaped end wall <NUM> wherein the distal end part <NUM> of the actuator <NUM> is arranged to protrude out of the distal end of the medicament delivery device and to act as a push button for a user, as will be described. A proximal surface of the end wall <NUM> is further arranged with proximally directed wedge-shaped protrusions <NUM>, which protrusions <NUM> are arranged to cooperate with the wedge-shaped cut-outs <NUM> on the toggle sleeve <NUM>, <FIG>.

At the distal end of the housing a generally tubular activator <NUM> is arranged, <FIG>. It has a distal grip part <NUM> that when connected to the distal housing part <NUM> is placed distally of the distal housing part <NUM> and having a diameter somewhat larger than the diameter of the distal housing part <NUM>. The side surfaces of the grip part <NUM> may be arranged with grip elements, such as longitudinally extending ridges <NUM>. The grip part <NUM> is further arranged with two planar surfaces <NUM> directed inwards and towards each other in the radial direction. Two proximally directed tongues <NUM> extend from the planar surfaces <NUM>. The tongues <NUM> are arranged with cut-outs <NUM>. The grip part <NUM> is arranged to fit onto a distal area of a generally tubular proximal part <NUM> of the activator <NUM> wherein the planar surfaces <NUM> of the grip part <NUM> are abutting corresponding planar surfaces <NUM> of the proximal part <NUM> that are facing radially outwards. The planar surfaces <NUM> of the proximal part <NUM> are arranged with wedge-shaped protrusions <NUM> that are intended to fit into the cut-outs <NUM> of the tongues <NUM> and lock the grip part <NUM> to the proximal part <NUM> when the two parts are assembled.

The proximal tubular part <NUM> of the activator <NUM> is arranged with an outwardly, circumferentially extending, ledge <NUM> in a proximal area thereof. Further, the grip part <NUM> is arranged with a proximally directed edge <NUM> such that when the grip part <NUM> is assembled with the proximal part <NUM>, an annular recess is formed between the ledge <NUM> and the edge <NUM>. A locking ring <NUM> is positioned rotationally in the recess between the ledge <NUM> and the grip part <NUM>. The locking ring <NUM> is arranged with protrusions <NUM> on its outer surface, which protrusions <NUM> are arranged to fit into recesses <NUM>, <FIG>, on an inner surface of the distal housing part <NUM>. Further, the outer surface of the locking ring <NUM> is arranged with ledges <NUM>, which ledges <NUM> fit into longitudinally extending recesses <NUM> on the inner surface of the distal housing part <NUM>, <FIG>. This locks the activator <NUM> to the distal housing part <NUM>, allowing rotation of the activator <NUM>, as will be described.

Further, the proximal part <NUM> of the activator <NUM> is provided with a number of resilient arms <NUM> that extend in the circumferential direction of the activator <NUM>. The arms <NUM> have a resiliency in the radial direction. The free ends of the arms <NUM> of the activator <NUM> are designed to be in contact with an inner surface of the locking ring <NUM> so as to cause a frictional resistance so as to avoid unwanted spontaneous movement of the activator <NUM> if the medicament delivery device for example is shaken. Further, the inner surface of the locking ring <NUM> is arranged with ledges <NUM> having surfaces in the circumferential direction, which ledges <NUM> cooperate with the free ends of the arms <NUM> so that the activator <NUM> can only be turned in one direction. Also, the inner surface of the proximal part <NUM> is arranged with two curved surfaces <NUM> provided at opposite sides and facing each other, having a curvature generally corresponding to the outer surface of the actuator <NUM>. The curved surfaces are limited in the circumferential direction by longitudinally extending guide ledges <NUM>, the function of which will be described below.

Further, at the proximally directed end surface of the activator <NUM>, a number of proximally directed wedge-shaped protrusions <NUM> are arranged. These wedge-shaped protrusions <NUM> are designed to interact with at least one corresponding wedge-shaped protrusion <NUM> on a distal end surface of a generally tubular activator sleeve <NUM>, <FIG> and <FIG>, which activator sleeve <NUM> is arranged rotational and slidable inside the distal housing part <NUM> and coaxial and outside the actuator <NUM>. The inner surface of the activator sleeve <NUM> is arranged with two inwardly directed protrusions <NUM> at a proximal area thereof, which protrusions <NUM> are designed with a number of side surfaces having different inclinations as seen in <FIG>. The protrusions <NUM> are designed to be in contact with and follow the ledges <NUM> of the actuator <NUM> as will be described. Adjacent the protrusions <NUM>, cut-outs <NUM> are provided, enabling some flexing in the radial direction of the protrusions <NUM>.

The activator sleeve <NUM> is further arranged with a spirally extending groove <NUM> on its outer surface, <FIG>. The groove <NUM> has an end wall <NUM> at the proximal end of the activator sleeve <NUM>. The groove <NUM> is intended to interact with at least one ledge <NUM> arranged on an inner surface of a stop ring <NUM>, which stop ring <NUM> is positioned coaxially outside the activator sleeve <NUM>. The outer surface of the stop ring <NUM> is arranged with longitudinally extending ledges <NUM>, which ledges <NUM> are designed to fit into the longitudinally extending recesses <NUM> on the inner surface of the distal housing part <NUM> as seen in <FIG>. This connection provides a rotational lock of the stop ring <NUM> while allowing movement in the longitudinal direction. The stop ring <NUM> is further arranged with proximally directed tongues <NUM>, which tongues <NUM> are arranged to cooperate with ledges <NUM> on either side of the recesses <NUM> for providing guiding stability of the stop ring <NUM> as will be described.

The invention is intended to function as follows. When the device is delivered to a user, the plunger rod <NUM> is in its most distal position as shown in <FIG>. Further the actuator <NUM> is in its most proximal position, with only a short part of the distal push button part <NUM> extending through the distal end of the medicament delivery device. The actuator <NUM> is locked in that position by the protrusions <NUM> of the activator sleeve <NUM> being in contact with the distal surface of the ledge <NUM>VII of the actuator, <FIG>. This prevents movement of the actuator <NUM> in the distal direction against the urging force of the toggle sleeve spring <NUM> that is tensioned between the toggle sleeve <NUM> and the actuator <NUM>. The activator <NUM> is in an initial position where the ends of the resilient arms <NUM> of the proximal part <NUM> are resting against the ledges <NUM> of the wedge-shaped protrusions on the inner surface of the locking ring <NUM>.

The medicament delivery device could either be delivered to a user with a medicament container <NUM> already mounted in the proximal housing part <NUM> and thus ready to use or be delivered without a medicament container mounted and possibly also with the proximal housing part <NUM> unconnected to the distal housing part <NUM>, wherein the user has to put a medicament container <NUM> inside the proximal housing part <NUM> and then attach the proximal housing part <NUM> to the distal housing part <NUM> of the medicament delivery device. The container fastener <NUM> with the spring <NUM> is now pressing the medicament container in the proximal direction, thereby reducing the risk of rattling of the medicament container.

In either way, when the medicament delivery device is to be used, the protective cap <NUM> is removed and a medicament delivery member is attached to the neck portion <NUM> of the proximal housing part <NUM>. When the medicament delivery member is an injection needle, the attachment causes a distal pointed end of the injection needle to penetrate the septum <NUM> of the medicament container, thereby causing a flow passage through the needle from the interior of the medicament container <NUM>.

In order to unlock and activate the medicament delivery device, the user turns the grip part <NUM>, which is counter clockwise in the embodiment shown. Any rotation in the opposite direction is prevented by the arms <NUM> of the proximal part <NUM> engaging the ledges <NUM> of the wedge-shaped protrusions of the locking ring <NUM>. In the embodiment shown, there are three ledges <NUM> of the wedge-shaped protrusions along the inner circumference of the locking ring <NUM> with thus a <NUM> degree displacement between the ledges <NUM>, and consequently the activator <NUM> is turned <NUM> degrees per step, as will be described in more detail below.

The initial mutual positions of the proximal part <NUM> and the activator sleeve <NUM> are shown in <FIG>. In this position, the at least one wedge-shaped protrusion <NUM> of the proximal part <NUM> is in full contact with the space between the protrusions <NUM> of the activator sleeve <NUM>, causing a rotational lock between the two components. When the grip part <NUM> with the proximal part <NUM> is turned, the activator sleeve <NUM> follows, whereby its protrusions <NUM> will slide along the ledge <NUM>VII of the actuator <NUM> until the protrusions <NUM> come to the steep ledge <NUM>I, <FIG>. This will enable the actuator <NUM> to be moved in the distal direction by the toggle sleeve spring <NUM> acting between the distal end of the driver <NUM> and the toggle sleeve <NUM>, which in turn is abutting the distal end surface of the actuator <NUM>, which in turn causes the push button part of the actuator <NUM> to extend in the distal direction through the distal end of the medicament delivery device. During the turning of the activator sleeve <NUM>, the ledge <NUM> of the stop ring <NUM> will slide in the spiral groove <NUM> of the activator sleeve <NUM>.

The user now stops turning the activator <NUM> but since the protrusions <NUM> of the activator sleeve is in contact with the steep inclined ledge <NUM>I of the actuator <NUM>, the activator sleeve <NUM> continues to rotate because the actuator <NUM> is rotationally locked to the housing by the ledges <NUM> cooperating with the ledges <NUM> of the distal housing part <NUM>. When now the proximal part <NUM> is stationary and the activator sleeve <NUM> is rotating, the inclined surface of the at least one wedge-shaped protrusion <NUM> of the activator sleeve <NUM> will cooperate with the inclined surface of the wedge-shaped protrusions <NUM> of the proximal part <NUM>, whereby the activator sleeve <NUM> is forced in the proximal direction. The rotation of the activator sleeve <NUM> is stopped when the protrusions <NUM> are moved in contact with the circumferential ledge <NUM>II of the actuator <NUM>, which stops the movement in the distal direction of the actuator <NUM>, <FIG>. The push button part <NUM> of the actuator <NUM> is protruding out of the distal end of the medicament delivery device as seen in <FIG>. When the actuator <NUM> is moved in the distal direction, the ledges <NUM> on the outer surface of the actuator will be positioned parallel to the guide ledges <NUM> of the proximal part <NUM> of the activator <NUM>, thereby preventing any turning of the activator <NUM>.

When the actuator <NUM> is moving in the distal direction as described above, so is the toggle sleeve <NUM> since they are in contact with each other because the toggle spring is acting on the toggle sleeve <NUM>, in turn acting on the actuator <NUM>. In the initial position the protrusions <NUM> of the driver <NUM> are positioned in the junction between the first and second sections <NUM>I and <NUM>II of the edge surfaces <NUM> as seen in <FIG>. When now the toggle sleeve <NUM> is moving in the distal direction together with the actuator <NUM> the protrusions <NUM> will slide along the first section <NUM>I, <FIG>, and because it has an inclination β in relation to the longitudinal direction, the toggle sleeve <NUM> will turn in relation to the driver <NUM>. The driver <NUM> is prevented from turning in the anti-clockwise direction due to the ledges <NUM> of the driver <NUM> cooperating with the ledges <NUM> of the end wall <NUM> of the housing. The turning of the toggle sleeve <NUM> will cause it to move somewhat in the proximal direction in relation to the actuator <NUM> because of the cooperation between the ramped cut-outs <NUM> of the toggle sleeve <NUM> and the wedge-shaped protrusions <NUM> of the actuator <NUM>, <FIG>. During continued movement of the toggle sleeve <NUM> in the distal direction, the protrusions <NUM> of the driver <NUM> will come out of contact with the first section <NUM>I whereby the toggle sleeve <NUM> will be turned back to the initial position because of the cooperation between the ramped cut-outs <NUM> and the wedge-shaped protrusions <NUM> as seen in <FIG>.

The device is now activated and ready to deliver a dose of medicament. If a medicament delivery member has not been attached before, it may be attached now to the proximal end of the medicament delivery device. The proximal end of the medicament delivery device is now placed at a dose delivery site, and if the medicament delivery member is an injection needle, a penetration is performed at the dose delivery site. The next step is to deliver a dose of medicament. The user then presses on the push button part <NUM> of the actuator <NUM> so that it moves in the proximal direction. This will cause the inclined ledge <NUM>IV of the actuator <NUM> to be moved in contact with the protrusions <NUM> of the activator sleeve <NUM>, <FIG>. This will in turn move the activator sleeve <NUM> in the proximal direction whereby the wedge-shaped protrusions <NUM> of the activator sleeve <NUM> are moved out of contact with the wedge-shaped protrusions <NUM> of the proximal part. Any turning of the activator <NUM> will thus not affect the medicament delivery device. At the same time, the activator sleeve is turned due to the inclination of the ledge <NUM>IV.

As the actuator <NUM> is moved in the proximal direction, so is the toggle sleeve <NUM>. This movement will cause the first section <NUM>I of the cut-outs <NUM> to come in contact with the protrusions <NUM> of the driver, <FIG>, and continuous movement of the toggle sleeve <NUM> will cause the protrusions <NUM> to slide along the inclined first section <NUM>I, <FIG>, whereby the driver <NUM> is turned in the clockwise direction. The turning is not obstructed by the ledges <NUM> of the driver <NUM> and the ledges <NUM> of the end wall <NUM> of the housing. The turning of the driver <NUM> will in turn cause a turning of the plunger rod <NUM> because of the rotational lock between them and since the plunger rod <NUM> is threadedly connected to the passage <NUM> of the end wall <NUM> of the housing <NUM>, the plunger rod <NUM> will be moved in the proximal direction, <FIG>, whereby it will act on the stopper <NUM> for expelling a dose of medicament through the medicament delivery member.

During the movement in the proximal direction of the actuator, the protrusions <NUM> of the activator sleeve <NUM> will enter the ramped part and at the end of the movement of the actuator <NUM> pass the ledge <NUM>, causing the actuator <NUM> to be locked in the depressed position, <FIG>. The passing of the ledge <NUM> by the protrusions <NUM> is facilitated by the flex obtained by the cut-outs <NUM>. There is further a safety feature, should the user during the pressing of the actuator <NUM> in the proximal direction suddenly release the actuator <NUM> before completing the dose delivery sequence. In this case only a part of the amount of medicament has been delivered. The toggle sleeve spring <NUM> will then try to force the actuator <NUM> in the distal direction. However, this is prevented in that the protrusion <NUM> will be moved in contact with the circumferentially extending ledge 90v, <FIG>, thereby preventing further movement. If not stopped, it would otherwise lead to the actuator <NUM> being again moved to a fully extended position, whereby it would be possible to deliver a new full amount of medicament. This is now prevented by the ledge 90v. The user may now press on the partly extending push button part <NUM> for delivering the remainder of the dose of medicament, after which the actuator <NUM> is locked as described above.

The medicament delivery device may now be removed from the dose delivery site, the medicament delivery member removed and discarded in a safety container and the protective cap <NUM> re-connected to the proximal end of the medicament delivery device. The above mentioned sequences of dose setting and dose delivery are repeated until the medicament container <NUM> is empty and as described above, the ledge <NUM> of the stop ring <NUM> is moved a distance along the spiral groove <NUM> of the activator sleeve <NUM> for each dose setting operation, whereby the stop ring <NUM> is moved in the proximal direction. In order to prevent setting a dose that is larger than the remaining dose quantity of the medicament container, the length of the spiral groove <NUM> around the circumference of the activator sleeve <NUM> corresponds to the total amount of medicament in the medicament container. Thus, the setting of the last dose may be limited by the ledges <NUM> of the stop ring <NUM> abutting the end wall <NUM> of the groove <NUM>, <FIG>, preventing further turning of the activator <NUM> and the activator sleeve <NUM>. This means that no dose larger than the remaining amount of the medicament container <NUM> can be set.

Claim 1:
An actuation mechanism (<NUM>) to be used with a medicament delivery device, comprising a generally tubular distal housing part (<NUM>) and a generally tubular proximal housing part (<NUM>) the actuation mechanism (<NUM>) comprising:
- a plunger rod (<NUM>) arranged to act on a stopper (<NUM>) of a medicament container (<NUM>);
- an actuator (<NUM>) arranged slidable and connected to the plunger rod (<NUM>) for acting on the stopper (<NUM>) when said actuator (<NUM>) is operated by displacing it in a longitudinal direction of the actuation mechanism (<NUM>);
- an activator (<NUM>) comprising a generally tubular activator sleeve (<NUM>) provided with a spirally extending groove (<NUM>) on its outer surface, the activator sleeve (<NUM>) is arranged rotational and slidable in the longitudinal direction inside the distal the housing part (<NUM>), wherein said activator sleeve (<NUM>) comprises protrusions (<NUM>) arranged to interact with said actuator (<NUM>) such that said activator sleeve (<NUM>) is rotated when said actuator (<NUM>) is operated, wherein said actuator (<NUM>) is arranged with ledges (<NUM>) cooperating with said protrusions (<NUM>), which ledges (<NUM>) are arranged inclined in relation to the longitudinal direction; wherein said actuator (<NUM>) is arranged with locking elements (<NUM>, <NUM>) arranged to cooperate with said protrusions (<NUM>) of said activator sleeve (<NUM>) such as to lock said actuator (<NUM>) after operation for delivering a dose of medicament;
- said groove (<NUM>) arranged with a length corresponding to the total amount of medicament to be delivered in a number of doses contained in said medicament container (<NUM>),
- said groove (<NUM>) provided with an end wall (<NUM>),
- a stop ring (<NUM>) arranged coaxial with said activator sleeve (<NUM>);
- said activator sleeve (<NUM>) and the stop ring (<NUM>) are arranged such that a follower (<NUM>)of the stop ring (<NUM>) is arranged on an inner surface of the stop ring (<NUM>) and positioned in said groove (<NUM>), said follower (<NUM>) is arranged to abut said end wall (<NUM>) at the proximal end of the activator sleeve (<NUM>) of said groove (<NUM>) when said total amount has been delivered.