Hand-held electronically controlled injection device for injecting liquid medications

A hand-held, electronically controlled injection device (1) for injecting preset doses of liquid medications, having a housing (2) for receiving a cartridge (4) containing the liquid medication and having a contact surface (16) for contacting a patient's skin; and actuator elements (41) for moving the cartridge (4) within the housing (2) to and from the contact surface (16).

TECHNICAL FIELD

The present invention relates to a hand-held, electronically controlled injection device for injecting liquid medications, and in particular of the type for performing subcutaneous injections fully automatically.

BACKGROUND ART

As is known, certain types of diseases, such as diabetes, call for injecting medications, such as insulin, several times a day, and the medication dosage to be injected may vary from one patient to another, and, for the same patient, during the day and from one day to another.

Over the past few years, therefore, electronically controlled injection devices have been devised and widely used to permit self-injection of medications in the required doses.

Patent Application US-A-2002/0133113 describes one such injection device substantially comprising a hand-held housing, which houses a cartridge containing the liquid medication for injection, and defines, on a contact surface for contacting the patient's skin, a through opening by which to fit a disposable needle to one end of the cartridge. The injection device also comprises an electromechanical actuator assembly, which is activated selectively to slide a plunger hermetically inside the cartridge body and deliver the liquid medication through the needle into the patient's skin.

Operation of the injection device is controlled by a programmable microprocessor, which receives signals from various switches and buttons—e.g. one or more medication dose selection buttons and an injection start button—and generates signals by which to control the actuator assembly according to a program stored in the microprocessor.

The injection device described therefore provides for selecting each medication dose for injection, and delivering the dose automatically.

Though functionally valid, the above type of injection device still leaves room for further improvement. More specifically, a need is felt for solutions designed to further reduce the amount of human intervention required, and to further safeguard users, with no medical experience, in preparing and self-injecting medications.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide an electronically controlled injection device for injecting liquid medications, designed to meet the above requirement, and which in particular provides for preparing and performing subcutaneous injections fully automatically.

According to the present invention, there is provided a hand-held, electronically controlled injection device for injecting preset doses of liquid medications, comprising a housing which is adapted for receiving a medication container containing the liquid medication, and has a contact surface for contacting a patient's skin, characterized by comprising first actuator means for moving said medication container within said housing to and from said contact surface.

BEST MODE FOR CARRYING OUT THE INVENTION

Number1inFIG. 1indicates as a whole a hand-held, electronically controlled injection device for injecting liquid medications, and in particular for performing subcutaneous injections fully automatically.

Injection device1substantially comprises a hand-held housing2defining a seat3for receiving a cartridge4containing the liquid medication; an injection driving unit5(FIGS. 2 and 3) housed inside housing2and selectively activated to cooperate with cartridge4and inject the patient with a preset dose of medication; and an electronic control unit6(FIG.12)—in the example shown, a microprocessor—also housable inside housing2to control operation of injection driving unit5.

More specifically, housing2, in the example shown, is of thin prismatic shape, and comprises a front wall7fitted with an LCD display8and set-up buttons9(operation of which is described in detail later on); a rear wall10; two sides11,12; a bottom wall15defining a contact surface16for contacting the patient's skin; and a top wall17fitted with an injection start button18, as explained in detail later on.

As shown inFIG. 1, one of the sides (11) of housing2has a door19hinged at the bottom about an axis perpendicular to front wall7and rear wall10, and which opens outwards to permit insertion of cartridge4inside seat3.

In the example shown, seat3for receiving cartridge4has an axis A perpendicular to bottom wall15and top wall17, and is formed close to side11.

Close to the opposite side12, housing2also defines a seat20(FIGS. 1 to 3) having an axis parallel to axis A, and for receiving one or more batteries21for electrically powering injection device1, and which are inserted through a further door22formed in bottom wall15.

As shown inFIGS. 1 to 11, cartridge4is defined by a hollow cylindrical body23containing a predetermined quantity of liquid medication, and having a closed, small-section end24, through which a commonly marketed disposable needle25is insertable in known manner, and an open opposite end26engaged in fluidtight manner by a disk-shaped member or plunger27, which is activated by injection driving unit5to slide inside body23and deliver the medication through needle25.

Cartridge4is inserted inside housing2with end24for needle25facing bottom wall15and, therefore, contact surface16for contacting the patient's skin; and bottom wall15has a through opening30, of axis A, by which to fit and remove needle25to/from cartridge4, and through which needle25is ejected to inject the skin.

Cartridge4has known external markings (not shown), e.g. bar codes, notches, conducting or reflecting material in a predetermined pattern, etc., by which to determine the presence of cartridge4inside housing2, and to obtain information relating to the medication, such as composition, concentration, expiry date, etc. Another possibility for identifying cartridge4is to use a radio frequency identification system.

As shown clearly inFIGS. 4 to 6, needle25is supplied in a protective needle housing31to prevent injury to the user, and defines, with needle housing31, a needle assembly32.

More specifically, needle25is fixed to and projects from a plastic needle support33which fits onto end24of body23of cartridge4.

As is known, needle25comprises a front portion34(at the bottom inFIGS. 2 to 11) for piercing the patient's skin and which projects from needle support33; and a rear end35(at the top inFIGS. 4 to 11) enclosed in needle support33and which fits through end24of body23of cartridge4. More specifically, needle support33comprises a number of elastic flanges surrounding rear end35of needle25, and which engage end24of body of cartridge4as described in detail later on.

As an alternative not shown, the reverse arrangement of the engagement between the needle support and the cartridge end is also possible; in this latter case, the cartridge end may be provided with elastic flanges engaging the needle support. This further embodiment has the advantage that the needle support need not be specially designed with elastic flanges, but rather a standard commercially available needle assembly may be used (even one with screw threads, which is a common commercially available version).

Needle housing31is defined by a cylindrical, cup-shaped body housing front portion34of needle25, and the open end of which is fitted to needle support33. In the example shown, needle assembly32also comprises an inner needle housing37covering front portion34of needle25.

With reference toFIGS. 2 and 3, injection driving unit5comprises an electromechanical actuator assembly40, which is selectively activated to act on plunger27of cartridge4and move it, inside body23of cartridge4, towards end24to deliver the liquid medication through needle25.

According to an important aspect of the present invention, injection driving unit5comprises a further electromechanical actuator assembly41for moving cartridge4, inside housing2and along axis A, to and from contact surface16to automatically fit and remove needle25to/from cartridge4, and to insert needle25inside the patient's skin at a predetermined speed.

More specifically, cartridge4is fitted to a supporting sleeve42which slides axially inside seat3of housing2.

As shown inFIGS. 2 and 3, supporting sleeve42is open, not only at opposite axial ends, but also on the side facing door19to permit insertion of cartridge4.

More specifically, supporting sleeve42comprises a small-section bottom end portion38for receiving end24of cartridge4, and which, when fitting needle25to cartridge4, is engaged by elastic flanges36of needle support33. End portion38also defines an annular shoulder39with the rest of supporting sleeve42.

Actuator assembly40comprises an electric gear motor43; a push member44which acts on plunger27of cartridge4to move it, inside body23of cartridge4, towards end24; and a transmission45for converting the rotation generated by gear motor43into translation of push member44.

More specifically (FIG. 2), transmission45substantially comprises a pinion46fitted to the output member of gear motor43; a screw assembly47connected to push member44; and an intermediate gear48having external teeth meshing with pinion46, and internal teeth engaging a leadscrew49of screw assembly47.

More specifically, leadscrew49is fitted to housing2to rotate but not translate axially; and screw assembly47also comprises a nut screw50fitted to leadscrew49, integral with push member44, and fitted to housing2to translate along, but not rotate with respect to, leadscrew49.

Push member44is advantageously defined by the core of a known Bowden-type flexible cable51, the sheath52of which has a portion fixed to housing2, e.g. to top wall17.

Actuator assembly41comprises an electric gear motor53; a slide54integral with supporting sleeve42of cartridge4and movable parallel to axis A; and a transmission55for converting the rotation generated by gear motor53into translation of slide54.

More specifically (FIG. 3), slide54is defined by a nut screw projecting laterally from supporting sleeve42and fitted to housing2to translate along, but not rotate with respect to, an axis parallel to axis A. Transmission55comprises a pinion56fitted to the output member of gear motor53; a leadscrew57connected to slide54and fitted to housing2to rotate about, but not translate along, its own axis; and an intermediate gear58having external teeth meshing with pinion56, and internal teeth engaging leadscrew57.

With reference toFIGS. 4 to 11, injection device1also comprises two or more retaining elements60extending about seat3to keep needle assembly32fitted to housing2in a predetermined position (FIG. 5), in which needle assembly32projects along axis A from bottom wall15of housing2, and the portion having needle support33engages opening30in wall15.

More specifically, retaining elements60are defined by levers extending parallel to axis A and having top ends61hinged to a structural portion of housing2, and free bottom ends having locking flanges62. More specifically, locking flanges62are located at opening30, and extend perpendicular to axis A and inwards of opening30.

Retaining elements60are loaded elastically inwards of seat3to assume a lock configuration (FIGS. 5,6,10and11), and are parted into a release configuration (FIGS. 4,7,8and9) by respective cam profiles63interacting with a contoured annular projection64on supporting sleeve42, as supporting sleeve42moves along axis A.

More specifically, supporting sleeve42and, with it, cartridge4are movable jointly by actuator assembly41in opposite directions along axis A to assume three distinct positions, namely:a top limit position (FIGS. 4 and 7) in which cartridge4is loaded and any automatic operation of injection device1(in this case, assembling and removing needle25, and injecting the patient with medication) starts and ends;a bottom limit position (FIGS. 10 and 11) in which needle25is removed from cartridge4; andan operating position (FIG. 6), close to the bottom limit position, in which the liquid medication is delivered through the patient's skin, and needle25is connected to cartridge4.

As shown inFIGS. 4 to 11, the cam profile63of each retaining element60and the projection64on sleeve support42are in the form of complementary ramps and designed to cooperate mutually to part retaining elements60in and close to the top limit position of supporting sleeve42, and to detach from each other, leaving retaining elements60subjected solely to the elastic return force towards axis A, in the other positions assumed by supporting sleeve42during its movement.

As shown inFIGS. 5 and 6, in the lock configuration, locking flanges62of retaining elements60cooperate with an outer rib65, formed at the open end of needle housing31, to retain needle assembly32inside opening30in bottom wall15as supporting sleeve42moves into the operating position, so that end portion38of supporting sleeve42fits inside the elastic flanges of needle support33, and the rear end35of needle25is inserted inside end24of cartridge4.

As supporting sleeve42moves subsequently from the operating position to the top limit position, locking flanges62of retaining elements60, still in the lock configuration, press on needle housing31to prevent it following needle25, needle support33and inner needle housing37moving together with supporting sleeve42, so that needle25and needle support33can be connected to cartridge4and withdrawn from needle housing31automatically.

One will note that retaining elements60, as they press on needle housing31, lock needle housing31with respect to the user too. Thus, untimely removal of needle housing31by the user, e.g. as needle25is being connected to cartridge4, is prevented.

In the bottom limit position of supporting sleeve42(FIGS. 10 and 11), locking flanges62of retaining elements60engage the gap between shoulder39of supporting sleeve42and the rear end of needle support33to arrest needle support33as supporting sleeve42subsequently moves into the top limit position, so that needle25and needle support33are withdrawn automatically from cartridge4after use.

With reference toFIG. 12, control unit6receives a number of signals from various detecting elements and buttons on injection device1, and supplies control signals for gear motors43,53and display8, according to a program stored in control unit6itself.

More specifically, control unit6receives the following signals:signals S1from sensors66(e.g. optical, electrical, radio-frequency, infra-red, etc.) facing seat3and for detecting the markings on cartridge4;a signal S2from a presence sensor67, e.g. a contact switch, located at opening30in bottom wall15and for determining engagement of the opening by an outer body of predetermined diameter, e.g. needle housing31;a signal S3from a skin sensor68, e.g. a mechanical or capacitive sensor, located on bottom wall15of housing2and for determining contact with the patient's skin;signals S4from set-up buttons9, by which to select, for example, the dose for injection, the speed at which needle25penetrates the patient's skin, medication delivery speed, etc; anda signal S5from injection start button18.

On the basis of the incoming signals, control unit6supplies signals C1and C2for controlling respective gear motors43,53in both rotation directions, and a signal C3for controlling display8.

Control unit6has its own internal memory70(shown externally for the sake of simplicity) which stores the action program of control unit6and the doses and timing of the injections performed, so as to inform the patient and/or doctor of these and the number of doses left in cartridge4. The doctor can therefore check patient compliance.

Injection device1is also provided with an interface (known per se and not shown), e.g. a USB port, a Bluetooth communication, a infra-red port, etc., that allows information exchange with a computer for data analysis.

Programming of injection device1may also be possible (for example by uploading from a computer), which may be useful for clinic trials (for example, permitting injection only of certain amounts and at certain times/intervals).

Operation of injection device1will be described as of theFIG. 4configuration, in which supporting sleeve42has no needle25and is set to the top limit position, and cartridge4has been inserted through door19into seat3of housing2and connected to supporting sleeve42.

Assembly of needle25to cartridge4is controlled fully automatically by control unit6, and is activated by simply inserting needle assembly32, by the open end of needle housing31, inside opening30in bottom wall15of housing2. Insertion of the needle assembly is immediately detected by presence sensor67, so that control unit6activates gear motor53in the direction designed, via transmission55and slide54, to move supporting sleeve42into the operating position.

As a result of the above movement of supporting sleeve42, projection64is detached from cam profiles63, so that retaining elements60move inwards of opening30, and locking flanges62close onto needle housing31to lock it in position partly engaging opening30(FIG. 5).

Needle assembly32can be inserted inside opening30either by hand or using an adapter indicated as a whole by71inFIGS. 4 to 10.

More specifically, adapter71is double-cup-shaped, and comprises opposite portions72,73of different diameters defining respective cavities open on opposite sides and for housing needle housing31and inner needle housing37respectively. The larger-section portion72also houses a cylindrical slip sleeve76defining the actual seat for needle housing31, and the function of which is explained later on; and the smaller-section portion73is provided internally, close to the open end, with an inner rib74which presses on inner needle housing37to remove it from the assembly defined by needle25and needle support33.

As supporting sleeve42reaches the operating position (FIG. 6), end portion38is inserted between elastic flanges36and connected to needle support33, and the rear end35of needle25is inserted inside end24of cartridge4.

At this point, the rotation direction of gear motor53is inverted, and supporting sleeve42moves from the operating position to the top limit position. As it does so, needle support33, needle25and, with it, inner needle housing37are withdrawn axially from needle housing31locked partly engaging opening30by retaining elements60.

Close to the top limit position, projection64on supporting sleeve42interacts with cam profiles63of retaining elements60to part retaining elements60, so that locking flanges62move outwards of opening30to release needle housing31(FIG. 7).

Once supporting sleeve42reaches the top limit position, adapter71can be inserted through opening30into seat3by portion73, the cavity of which is thus engaged by inner needle housing37. Given its smaller diameter, insertion of portion73is not detected by presence sensor67. When adapter71is extracted from opening30, inner needle housing37is removed from needle25(FIG. 8).

Consent to start the actual injection is given by surface16contacting the patient's skin and so activating skin sensor68.

When start button18is pressed, gear motor53is first activated and, via transmission55, moves supporting sleeve42back into the operating position, so that needle25penetrates the patients skin. Gear motor43is then activated and, via transmission45and push member44, acts on plunger27of cartridge4to slide it towards end24and deliver a predetermined dose of liquid medication.

Before the injection is performed, the dose to be injected, the speed at which needle25penetrates the patient's skin, the speed at which the liquid medication is delivered and the injection depth can be selected using set-up buttons9and displayed on display8.

Once the injection is completed, supporting sleeve42moves back into the top limit position.

Needle25can be removed from cartridge4fully automatically using adapter71(FIGS. 9 and 10), or directly using a needle box75(FIG. 11), e.g. of the type known by the trade name “SHARPS BOX”.

More specifically, when using adapter71used to remove needle housing31and inner needle housing37(FIGS. 9 and 10), slip sleeve76must first be extracted from portion72to rest axially on rib65of needle housing31.

At this point, needle housing31and the extracted part of slip sleeve76are inserted through opening30in housing2to activate presence sensor67, so that control unit6activates gear motor53to move supporting sleeve42from the top limit position to the bottom limit position.

As cam profiles63are detached from projection64on supporting sleeve42, retaining elements60are prevented from moving into the lock configuration by locking flanges62resting on slip sleeve76of adapter71(FIG. 9).

As supporting sleeve42reaches the bottom limit position (FIG. 10), however, locking flanges62of retaining elements60click inside the gap between shoulder39on supporting sleeve42and the top axial end of needle support33.

At this point, the rotation direction of gear motor53is inverted, and supporting sleeve42moves into the top limit position. As it does so, needle support33and needle25remain in the position in which they are retained by locking flanges62, and are thus withdrawn axially from supporting sleeve42and cartridge4.

As supporting sleeve42reaches the top limit position, retaining elements60are again parted, and injection device1is ready to be fitted with another needle25for the next injection.

When using needle box75(FIG. 11), this is simply inserted by the mouth end inside opening30to activate presence sensor67and automatically remove needle25from cartridge4in exactly the same way as described relative to adapter71.

The advantages of injection device1according to the present invention will be clear from the foregoing description.

In particular, by permitting control of the movement of cartridge4to and from contact surface16, injection device1provides for fully automatically fitting and removing needle25to/from cartridge4, and controlling the speed at which needle25penetrates the patient's skin.

In other words, when the actual injection is performed, it is possible to set not only the medication dose and the speed at which the dose is delivered, but also the speed at which needle25is ejected from housing2, and therefore skin penetration speed.

Clearly, changes may be made to injection device1as described and illustrated herein without, however, departing from the scope of the accompanying Claims.

In particular, the movement of cartridge4and delivery of the medication contained in cartridge4may be controlled using a single gear motor, which may, for example, by means of a transmission similar to those described, control axial displacement of the core of a Bowden-type flexible cable acting on plunger27of cartridge4; and releasable locking means may be provided for selectively making plunger27and body23of cartridge4integral with each other, so that, when the locking means are activated, cartridge4is moved to and from contact surface16, and, when the locking means are released, plunger27slides inside body23of cartridge4to deliver the medication.

Furthermore, injection device1can be used, in the same way as disclosed, with other types of medication containers, such as a syringe.

FIGS. 13-16show a hand-held, electronically controlled injection device80according to a second embodiment of the invention. Like the injection device1according to the first embodiment, the injection device80shown inFIGS. 13-16comprises, inside a housing81(shown inFIGS. 13,14only), a cartridge holder82for accommodating a cartridge83containing a liquid medication, a push member84designed to act on a plunger85of cartridge83, a first electromechanical actuator assembly86for driving push member84and a second electromechanical actuator assembly87for axially moving, in particular, cartridge holder82. A door88provided on a side wall of housing81, and actuated by a sliding button89provided on the same side wall, may be opened by being rotated about a pivot axis90to insert or remove a cartridge83into/from the injection device. Cartridge holder82is axially movable relative to door88but rotatable with door88about pivot axis90when in an axial retracted position.

Push member84comprises an axially incompressible and laterally flexible tube91, having the form of a spring, and deflected by 180° by a guiding rigid semi-circular housing92at an upper part of the device, and a piston93fixed to an end of tube91projecting from housing92along the axis B of cartridge holder82and cartridge83. Piston93is designed to cooperate with plunger85of cartridge83(seeFIG. 16) as well as with a movable recessed part94(seeFIG. 15) the function of which will be explained later on.

Under the control of a control unit95, represented inFIG. 41, first actuator assembly86may move push member84axially from a retracted position, in which piston93is outside cartridge83and within recessed part94(FIG. 15), towards a disposable needle96connected to cartridge83, so that piston93comes into contact with plunger85within cartridge83and pushes plunger85to deliver medication through needle96(FIG. 16). Push member84may then be moved back to its retracted position, leaving plunger85at the position it was pushed to.

Second actuator assembly87may be controlled by control unit95to move a structure comprising first actuator assembly86, push member84, push member housing92and cartridge holder82along axis B, i.e. to and from a bottom wall97of device housing81for contact with the patient's skin, to automatically fit and remove needle96to/from cartridge83and to insert and remove needle96into/from the patient's skin. More precisely, structure82,84,86,92may be moved between a top, retracted position in which needle96connected to cartridge83is within device housing81, and one or more bottom positions in which needle96projects from a through opening98provided in bottom wall97.

Referring toFIGS. 17,18, needle96is fixed to and projects from a plastic needle support99which fits onto a bottom end100of cartridge holder82so that the corresponding bottom end83aof cartridge83, surrounded by bottom end100, is pierced by the rear end101of needle96. Fitting of needle support99onto cartridge holder82is achieved by means of an intermediate metal member102fixed to bottom end100of cartridge holder82and having a number of elastic flanges103which may be compressed between the external circumferential wall of bottom end83aof cartridge83and the internal circumferential wall of needle support99in grooves82aprovided in the cartridge holder wall.

Before connection of needle96to cartridge83, needle support99, with needle96, is fitted in a protective needle housing or needle cap104and forms with the latter a needle assembly105(seeFIGS. 19-20).

Referring toFIGS. 19-20, the injection device80according to this second embodiment further comprises releasable retaining means for retaining needle assembly105in a predetermined position inside opening98of bottom wall97. These releasable retaining means comprise two or more releasable retaining tabs or fingers106, which are actuated by needle assembly105upon its insertion into opening98, and an axial abutment surface107which limits insertion of needle assembly105into opening98. Releasable retaining tabs106are disposed on the circumference of opening98and are subjected to an elastic load directed towards axis B. With abutment surface107, releasable retaining tabs106define gaps which are engaged by an annular upper flange108of needle housing104to lock needle assembly105in opening98. An electro-mechanical sensor (electric switch)109(FIG. 41), connected to releasable retaining tabs106, detects actuation of tabs106by needle housing104and sends an electric signal to control unit95.

Automatic connection of needle96to cartridge83is activated by the insertion of needle assembly105between tabs106. This insertion, immediately detected by sensor109, causes control unit95to activate second actuator assembly87to move down structure82,84,86,92inside device housing81from its retracted position. The retaining force exerted by retaining tabs106on needle housing104is sufficient for needle housing104to remain locked in its position shown inFIG. 20whilst bottom end100of cartridge holder82equipped with intermediate fixing member102engages needle support99(FIG. 21). Once movable structure82,84,86,92has reached a predetermined bottom position, in which bottom end100of cartridge holder82fully engages needle support99, thus connecting needle96to cartridge83, second actuator assembly87moves structure82,84,86,92back to its top, retracted position with needle support99and needle96connected to cartridge83, whilst needle housing104is retained by abutment surface107(FIG. 22).

Unlike retaining elements60in the first embodiment, retaining tabs106do not prevent the user from removing needle housing104during connection of needle96to cartridge83. However, any removal of needle housing104during the connection process is detected by sensor109. If such a removal occurs, control unit95immediately stops the connection process and controls the return of movable structure82,84,86,92to its top position. The user will then be proposed, via a display screen110(FIG. 41) provided on the injection device, to start a new connection process.

For detaching needle96from cartridge83, the user inserts the empty needle housing104into opening98up to engagement of retaining means106,107by needle housing104. Actuation of tabs106is detected by sensor109. This causes control unit95to activate second actuator assembly87to move structure82,84,86,92down to a bottom position where needle support99is fitted in needle housing104(FIGS. 23,24). The user may then actuate a needle release button111provided on device housing81and connected to control unit95, to move a square retaining member112transversely to axis B up to a position where a leg113of retaining member112, inserted in a gap between abutment surface107and annular upper flange108of needle housing104, is above the upper end of needle support99(FIG. 24). Thereafter, a reverse movement is imparted to structure82,84,86,92while needle support99and, with it, needle96are retained by retaining member112, thereby detaching needle support99and needle96from cartridge holder82and cartridge83(FIG. 25). The user can then disengage needle assembly105from retaining tabs106and take it out of the injection device.

According to an advantageous aspect of the invention, sensor means are provided in the injection device to detect connection of needle96to cartridge83. These sensor means, visible inFIGS. 26-29, comprise an optical transmitter114, such as a light-emitting diode, and first and second optical receivers115,116, such as photodiodes, fixed to the interior face of the front or the back wall of device housing81, and a reflector117, such as a mirror, fixed to the opposite, back or front wall of device housing81. Optical transmitter114is aligned with first and second optical receivers115,116in a direction parallel to axis B and placed between them. When cartridge holder82, more precisely movable structure82,84,86,92, is in the retracted position and no needle is connected to cartridge83(FIG. 26), a first optical ray118forming part of a beam transmitted by transmitter114passes a first time near bottom end100of cartridge holder82, is reflected by mirror117and passes a second time near bottom end100to reach first receiver115, and a second optical beam119transmitted by transmitter114passes a first time near bottom end100, is reflected by mirror117and passes a second time near bottom end100to reach second receiver116. As apparent inFIG. 27, the cross-section of an upper portion of bottom end100of cartridge holder82is only partly circular, i.e. bottom end100has a truncated, flat side portion120, to let first optical beam118pass. When needle support99, with needle96, is properly connected to bottom end100of cartridge holder82, optical beams118,119are interrupted by needle support99(FIG. 29). Receivers115,116thus no longer receive optical beams118,119. This is interpreted by control unit95as implying that a needle96is properly connected to cartridge83.FIG. 28shows an intermediate configuration where needle support99and needle96are only partly connected to cartridge holder82and cartridge83. In this configuration, the second optical beam119is interrupted by needle support99but the first one,118, still reaches first receiver115. This is interpreted by control unit95as implying that needle96is only partly connected to cartridge83.

Thus, after the needle connection process described above, if control unit95determines that no needle is connected to cartridge83or that a needle is only partly connected to cartridge83, the user is not allowed to initiate the injection and is proposed to restart the needle connection process. Security of use of the injection device is thus increased.

FIGS. 30 and 31show alternative sensor means for detecting connection of needle96to cartridge83. In this variant, one,103a, of the elastic flanges103of intermediate fixing member102is longer than the other(s). When cartridge holder82is in the retracted position and needle96is properly connected to cartridge83, the longest elastic flange103a, compressed between needle support99and bottom end83aof cartridge83, has an end portion which projects outside needle support99and defines a first angle α1with axis B. In this configuration, an optical ray transmitted by an optical transmitter121is reflected by the projecting end portion of flange103atowards an optical receiver122. Reception of a signal by optical receiver122is interpreted by control unit95as implying that needle96is properly connected to cartridge83. If, on the other hand, needle96is not properly connected to cartridge83, as shown inFIG. 31, then the projecting end portion of flange103adefines a second angle α2, different from the first angle α1, with axis B. In this case, the optical ray reflected by the projecting end portion of flange103ais not received by receiver122. This is interpreted by control unit95as implying that no needle is connected to cartridge83or that a needle is ill connected to cartridge83.

Returning toFIGS. 15 and 16, delivery of medication through needle96is, as explained above, carried out by piston93of push member84pushing plunger85of cartridge83. During this process, piston93and a portion of tube91is within cartridge83. Piston93and tube91remain within cartridge83so long as doses of medication are left therein. Once all doses of medication contained in cartridge83have been injected into a patient, push member84is retracted outside cartridge83to enable replacement of the latter (FIG. 15). A risk could however exist that, between two injections, the user opens door88to remove cartridge83from the injection device whilst push member84is still inside cartridge83. Such an operation could seriously damage push member84.

In order to eliminate this risk, the present invention advantageously provides a lock mechanism which locks/unlocks the opening mechanism of door88when push member84is inside/outside cartridge83.

With reference toFIGS. 32-40, the opening mechanism of door88comprises opening button89, which is slidable in a direction parallel to axis B, a lockable part123fixed to opening button89inside device housing81and comprising a flange124, a lever125actuated by lockable part123and a locking member126actuated by lever125. Lever125is mounted on an axis that is fixed relative to device housing81. Locking member126is mounted on movable structure82,84,86,92at a location situated on the opposite side of axis B with respect to opening button89and so as to be slidable with respect to movable structure82,84,86,92in a direction parallel to axis B, and has a recess with a flange127designed to cooperate with a corresponding flange128of cartridge holder82.

The lock mechanism comprises movable recessed part94and a lever129actuated by recessed part94and having, at one of its end, a flange130designed to cooperate with flange124of lockable part123. Lever129is mounted on an axis that is fixed relative to device housing81. Recessed part94is movable along axis B and fixed to one end of a spring131(visible inFIGS. 13-16) the other end of which is fixed to movable structure82,84,86,92.

Operation of the opening and lock mechanisms is as follows: during injection of a medication dose (FIGS. 32-34), movable structure82,84,86,92is in a bottom position, piston93of push member84is inside cartridge83and recessed part94is in a rest position, out of contact with lever129. In this configuration, flange130of second lever129engages flange124of lockable part123(FIGS. 33,34) so that lockable part123and, with it, opening button89are locked, i.e. cannot be moved up, thus preventing door88from being opened. Between two injections with the same cartridge83, movable structure82,84,86,92is in its retracted position, piston93of push member84is inside cartridge83and recessed part94is in a rest position, out of contact with lever129(FIGS. 35-37). In this configuration, flange130of second lever129still engages flange124of lockable part123(FIG. 37) so that lockable part123and, with it, opening button89remain locked, thus preventing door88from being opened. Once all medication doses contained in cartridge83have been injected, movable structure82,84,86,92and piston93of push member84are each retracted. During retraction of push member84, piston93enters the recess of recessed part94and pushes recessed part94upwards against the action of spring131so that recessed part94comes into contact with the end of second lever129opposite to the end having flange124to rotate lever129and thus disengage it from lockable part123(FIG. 40). Door opening button89may then be slid upwards as shown inFIG. 38. Upwards motion of opening button89causes first lever125to rotate to move locking member126down and thus disengage flange128of cartridge holder82from flange127of locking member126. Under the action of a spring, door88and, with it, cartridge holder82are then rotated about pivot axis90to enable extraction of cartridge83from cartridge holder82(FIG. 38). Door opening button89, lever125, locking member126and lever129are subjected to the action of respective springs which tend to maintain them in their rest position shown inFIGS. 32 to 34or35to37.