Needle safety module comprising a locking mechanism and a user identification

A needle safety module for being connected to an injection device for administering a liquid product to a patient, the module including a housing, a needle connected to the housing, and a needle protective sleeve having one end which can be placed on an injection point of the patient and displaced axially in relation to one of the needle or the housing from a starting position in which the needle tip is covered to an injection position in which the needle tip at least touches the injection point, the needle protective sleeve lockable in relation to one of the needle or the housing.

CROSS-REFERENCED RELATED APPLICATIONS

This application is a continuation of International Patent Application No. PCT/CH2007/000412 filed Aug. 22, 2007, which claims priority to German Patent Application No. DE 10 2006 041 128.5 filed Sep. 1, 2006, the entire content of both of which is incorporated herein by reference.

BACKGROUND

The present invention relates to device for injecting, infusing, administering, dispensing or delivering a substance, and to methods of making and using such devices. More particularly, the present invention relates to a needle safety module which can be attached to an injection device, e.g. an injection pen or so-called automatic injectors. A product or substance contained in the injection device, such as a liquid medicament, can be administered to a patient by or via the safety module. In some embodiments, the present invention relates to a mechanism designed to enable safe handling of a needle and, in some embodiments, to a code by or from which it is possible to tell whether a needle has been used.

Needle safety modules typically comprise a housing in which a needle is accommodated so that it is axially immobile. The housing can be attached to an injection device. The needle is surrounded by a needle guard before and after an injection so that the user of the safety module can not pierce himself with the needle. In addition to being painful, inadvertent piercing can lead to infections, such as HIV or hepatitis. For an injection, the needle guard is placed on the desired injection point and pushed back into an injection position by pressing the needle guard against the injection point, causing the needle to pierce the injection point. Once the needle has been pulled out, the needle guard is pushed back far enough over the needle to cover it, for example by a spring. In most instances, the needle is to be used only once.

U.S. Pat. No. 6,855,129 B2 discloses a needle safety module which is designed so that once the needle safety module has been used, a needle guard is prevented from moving axially. The mechanism has a locking sleeve which is initially guided by a housing as the needle guard is pushed back in the proximal (rearward) direction. Once the guided movement is complete, the locking sleeve is rotated by the needle guard as the needle guard continues to be pushed backward. This rotating movement continues as the needle guard is moved in the distal direction due to projections disposed on the housing and recesses in the proximal end of the needle guard until a projection of the locking sleeve locates in a lock element formed by the housing. As a result, the needle guard is prevented from moving any farther in the distal direction. The housing has an opening, through which the projection of the locking sleeve can be seen when the locking sleeve is engaged with the housing in a locked arrangement.

SUMMARY

One object of the present invention is to provide a needle safety module which offers a simple, reliable way of preventing a needle guard from being pushed back again, i.e. to expose or reveal the needle, after an injection. Another object of the present invention is to provide a needle safety module which makes it easier to tell whether the module, and needle therein, has already been used.

In one embodiment, the present invention comprises a needle safety module for being connected to an injection device for administering a liquid product or substance to a patient, the module including a housing, a needle connected to the housing, and a needle protective sleeve having one end which can be placed on an injection point of the patient and displaced axially in relation to one of the needle or the housing from a starting position in which the needle tip is covered to an injection position in which the needle tip at least touches the injection point, the needle protective sleeve lockable in relation to one of the needle or the housing.

In one embodiment, the present invention comprises a needle safety module for fixing to an injection device for administering a liquid product wherein the module comprises a housing, a needle that is connected in an axial manner to the housing, a needle protective sleeve, the distal end of which can be inserted onto an injection point and can be displaced axially in relation to the needle or the housing from a starting position in which the distal needle tip is covered to an injection position in which the distal end protrudes as far as the needle protective sleeve such that the distal needle tip touches at least the injection point in an end position in which the distal needle tip is covered, and wherein the needle protective sleeve is locked in an axial manner in its end position in relation to the needle or to the housing.

In one embodiment, a needle safety module in accordance with the present invention comprises a housing connected to an injection needle so that the needle is axially immobilized. The housing comprises a sleeve-like, cylindrical main part and a needle holder which form the housing when assembled. The injection needle may be connected to the needle holder or, in the case of a one-part housing, to the housing. Injection moulding processes are suitable for this purpose, by which plastic is cast around the needle. The sleeve-like housing or housing part may be attached to the distal (forward or front) end of an injection device. To this end, the housing may be provided with an appropriate fixing structure or feature, such as a screw, snapper or catch connection (e.g. snap-fit or click-fit connection). The needle may project out from the needle holder in the proximal direction so that when the needle safety module is attached to an injection device, the proximal end of the needle pierces a septum of a product container, thereby establishing a flow connection to the interior of the product container. The needle projects so far from the needle holder in the proximal direction that it is still laterally surrounded by the sleeve-shaped housing and does not project beyond the proximal end of the housing.

In some embodiments, the housing may be used to mount a needle guard so that it is able to slide relative to the housing. The needle guard may be mounted so that it can not rotate relative to the housing but is able to slide axially. While, in some embodiments, a non-rotating arrangement is preferred, it is not necessary. The needle guard is pushed in the distal direction by a spring or more generally an elastic means supported on the housing, e.g. on the needle holder and on the needle guard. For example, the needle guard may be closed at its distal end with the exception of a small orifice, the purpose of the orifice being to allow the needle to be extracted from the distal end of the needle guard. The spring is supported on the end face of the needle guard and on the needle holder of the housing. The needle guard can be placed on or against an injection point of a patient by its distal end or distal end face.

In some embodiments, the needle guard can be moved from an initial position via an injection position into an end position. The length by which the needle guard extends out from the housing in the distal direction and the length by which the needle extends out from the needle holder in the distal direction are adapted to one another so that the needle tip does not extend out from the needle guard in the initial position and in the end position. This rules out the possibility of a user of the device piercing himself with the distal needle tip when the needle guard is in the initial position and the end position. When the needle guard is in the injection position, the needle tip extends out from the needle guard far enough for the distal needle tip to at least touch the injection point and, in some embodiments, pierce the patient. In some embodiments, there is no possibility of the needle guard moving into its initial position when the distal needle tip is at least touching the injection point and, in some embodiments, the needle guard can only be pushed in the distal direction into an end position once the distal needle tip is touching the injection point. A so-called “early-triggering” needle safety module of this type rules out the risk of being infected with contagious germs because as soon as the needle tip has made contact with the body tissue of a first patient, the needle guard can only be moved into an end position. In the end position, the needle guard is locked so that it can not move axially relative to the needle or to the housing. This rules out any possibility of a second patient being infected by the needle tip, which might have been infected due to contact with the first patient.

In one aspect of the present invention, it is assumed that the needle guard is displaced by a specific distance measured in the direction in which the needle guard is moved between its initial position and its end position. This displacement enables the user to tell whether the needle safety module can still or can no longer be used. In some preferred embodiments, the needle guard is displaceable in the distal or proximal direction from its initial position into its end position. The needle guard may have one or more markings, for example, which can be seen when the needle guard is in the initial position or in the end position. A marking may be a colored marking or a symbol, a word or a character. The marking may be strip-shaped, for example, and extend around the circumference, for example ring-shaped. The marking may be disposed on the needle guard in the region of the distal end of the housing or in the region of an orifice or window of the housing so that the marking is visible when the needle guard is in the initial position or in the end position. When the marking is not visible, depending on the position of the needle guard, it may be covered by the housing.

If the marking is disposed on the needle guard in the region of the distal end of the housing in the case of a needle guard that is displaced in the proximal direction from the initial position to the end position, the marking will be visible in the initial position but will not be visible in the end position. Alternatively or in addition, a marking may be visible through the window in the initial position and not visible in the end position or vice versa.

If the needle guard is moved in the distal direction from the initial position to the end position, the marking, which is disposed on the needle guard in the region of the distal end of the housing, is not visible when the needle guard is in the initial position and visible in the end position. Alternatively or in addition, a marking may not be visible through the window in the initial position and visible in the end position, or vice versa.

The advantage of these designs is that a user can easily and reliably tell whether the needle guard is in the initial position or in the end position, in other words whether the needle safety module can still be used or has already been used.

In another embodiment of the present invention, the needle guard has a first marking which is visible when the needle guard is in an initial position and a second marking different from the first which is visible in an end position. In some preferred embodiments, the second marking is covered when the needle guard is in the initial position and the first marking is covered when the needle guard is in the end position.

For example, in the case of a needle guard which is moved in the proximal direction from the initial position to the end position, the following will apply: the first marking may be disposed on the needle guard in the region of the distal end of the housing and the second marking may be disposed on the needle guard in the region of a window, in which case the first marking is visible in the initial position and the second marking is visible in the end position, or vice versa. As an alternative or in addition, a first and a second marking may be provided in the region of the window, for example.

For example, in the case of a needle guard which is displaced in the distal direction from the initial position to the end position, the following will apply: the first marking may be disposed on the needle guard in the region of the distal end of the housing and the second marking may be disposed in the region of a window, in which case the first marking is visible in the end position and the second marking is visible in the initial position, or vice versa. As an alternative or in addition, a first and a second marking may be provided in the region of the window, for example.

By way of example and with a view to providing a clearer understanding, a marking which is visible when the needle guard is in the initial position may be green and a marking which is visible when the needle guard is in the end position may be red.

In a second aspect of the present invention, a lock element is provided on one of the needle guard and housing and a complementary lock element is provided on the other of the needle guard and housing, wherein in the end position, the lock element latches into the complementary element. In some preferred embodiments, the lock element is a projection or a cam and the complementary element may be a recess, which may be formed by or between two projections. The lock element or the complementary element may be disposed on a flexible, e.g. elastic and/or resilient arm(s) so that the lock element or complementary element can effect a latching movement. In some preferred embodiments, only one of the lock element and complementary element is disposed on such an arm. In some preferred embodiments, the lock element and the complementary element may be formed integrally on the needle guard or housing or needle holder.

In some preferred embodiments, the needle safety module has an activation cam, which, as the needle guard is being moved in the proximal direction out of the initial position, pushes the lock element or complementary lock element transversely to the direction of movement so that the lock element or complementary element can be moved past the activation cam. The activation cam may be formed on the element on which the lock element or complementary element is formed, e.g. on the housing or needle guard. In some embodiments, the lock element or complementary element touches the activation cam or slides along it as it moves past it. For example, when the needle guard is in the initial position, the lock element or complementary element may be disposed so far in front of the activation cam that the distance between the lock element or complementary element and the activation cam is shorter than the total distance to the needle guard. For example, the lock element or complementary element may touch the activation cam when the needle guard is in the initial position. The purpose of the activation cam is to prevent the lock element or complementary element from being returned to a position in front of the activation cam once the lock element or complementary element has moved past the activation cam, so that the needle guard is no longer able to move back into its initial position. In some preferred embodiments, a marking of the type explained above may have a maximum width extending in the direction of the longitudinal axis which corresponds to the distance which the lock element or complementary element must travel to move past the activation cam. Due to the relatively short distance which the needle guard must travel to move the lock element or complementary element past the activation cam, a needle safety module of this design may be referred to or thought of as “early triggering.”

In some preferred embodiments, the lock element or complementary element is moved past the activation cam as soon as the needle tip has made contact with the injection point so that the needle guard is guided into the end position during the movement in the distal direction and can no longer be moved into the initial position. Having moved past the activation cam, the lock element or complementary element snaps back in the direction from which it was deflected by the activation cam. For example, when the lock element or complementary element snaps back, it has moved past the activation cam.

In some preferred embodiments, the activation cam is disposed in an axial position such that the lock element or complementary element is moved past the activation cam at the latest when the distal needle tip is able to make contact with the injection point. In some embodiments, the needle length may also be adapted as a function of the axial position of the activation cam or vice versa.

In some embodiments, the activation cam is shaped so that the lock element or complementary element is pushed by the activation cam transversely to the direction in which the needle guard is moved as the needle guard is being moved in the distal direction away from a position in which the lock element or complementary element is moved past the activation cam. E.g., the lock element or complementary lock element is able to engage due to the movement transversely to the movement direction. The activation cam may have oblique surfaces or curves so that the lock element or complementary element is moved by the activation cam transversely to the direction of movement of the needle guard as the needle guard is being moved. The movement transversely to the direction of movement may be a movement in the radial direction or in the circumferential direction, e.g. at a tangent to the circumferential direction of the needle guard or housing.

In one preferred embodiment, the activation cam may serve as a lock element, in which case when the needle guard is moved in the distal direction from a position in which the complementary element is moved past the activation cam, the complementary element latches in the activation cam. The connections described here, which are established when the lock element is disposed in the complementary element, are designed so that they can not be released by a force applied to the needle guard in the distal or proximal direction without breaking the needle safety module.

In another preferred embodiment, the lock element or complementary lock element is disposed outside of, to the side, in front of or behind an alignment running through the activation cam extending in the direction of movement of the needle guard.

In yet another embodiment of the present invention, as an alternative to or in addition to the descriptions and explanations given above, it may be advantageous to provide a locking element which is displaceable relative to the housing and the needle guard, which in an initial position engages with the needle guard and the housing and blocks or prevents a movement of the needle guard only in the distal direction. The locking element may be of an integral design with the housing or needle holder, for example. Alternatively, the locking element may be an additional part, which is able to slide along the needle holder or is fitted on the needle holder prior to using the needle safety module. For example, the locking element may be integrally joined to the housing, needle holder or a part adjoining the needle holder by a flexible, e.g. an elastic, arm. The locking element may have at least one lock lug acting in the distal direction, which is supported on a shoulder in the housing. Due to the fact that the locking element is able to extend through the wall of the needle guard, a movement of the needle guard in the distal direction is blocked from the initial position.

In some preferred embodiments, the needle guard is designed so that when the needle guard moves in the proximal direction, the locking element is moved out of engagement with at least the housing, as a result of which the needle guard can be moved by a movement in the distal direction into the end position in which the needle guard is disposed distally of the initial position. In some embodiments, the needle guard and/or the locking element may be adapted to one another and/or have driving surfaces or ramps adapted to one another so that the movement of the needle guard is converted into a transverse movement of the locking element. In some preferred embodiments, the locking element is displaceable transversely to the direction of movement of the needle guard. After the transverse movement of the locking element, the locking element may still be engaged with the needle guard or may have engaged with the needle guard again. Having moved out of engagement with the housing, the locking element latches with the needle guard, wherein the locking element is at least partially slaved in the movement of the needle guard in the proximal or in the distal direction. For example, once the needle guard has been pushed in the proximal direction, the locking element is moved out of engagement with the housing and needle guard, then latches in the housing and is then driven by the needle guard in the distal direction as the needle guard moves back in the distal direction. In the end position, namely when the needle guard is in a position disposed distally of the needle guard when in its initial position, the lock element provided on the needle guard can then engage with the complementary lock element formed by the housing so that the needle guard and housing latch and are axially fixed.

It should be understood that the first and second aspects or any embodiments of the present invention may complement one another and may therefore be combined with one another.

DETAILED DESCRIPTION

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, the latter particularly with regard to the electrical system of the invention, if any. In embodiments with electrical features or components, suitable electrical components and circuitry, wires, wireless components, chips, boards, microprocessors, inputs, outputs, displays, control components, etc. may be used. Generally, unless otherwise indicated, the materials for making the invention and/or its components may be selected from appropriate materials such as metal, metallic alloys, ceramics, plastics, etc. It should be understood that any use herein of relative positional, directional or orientational terms is for convenience of description and is not intended to be limiting.

FIG. 1illustrates several views of a first embodiment of the present invention wherein a needle safety module comprises a housing2and a needle guard3mounted on it which is able to move along a needle1. As illustrated inFIG. 1, the needle guard3is disposed in the initial position. The needle guard3is pushed in the distal (forward or front) direction and held in its initial position by a spring9. The spring9is supported on a needle holder11, which is connected to the housing2so that it can not move axially, and on a collar-shaped distal end of the needle guard3pointing toward the mid-axis. A lock element4is located in a groove7, formed by the needle guard3. In the perspective view shown on the right-hand side, the groove is provided in the form of an orifice. The groove may also be of a pocket-type shape rather than an orifice, as illustrated in the perspective view shown on the left-hand side ofFIG. 1. The lock element4is integrally joined to the needle holder11via an arm in a flexible, e.g. elastically or resiliently deformable, manner. The needle holder11is connected to the housing2in a non-positive manner. Alternatively, the needle holder11could be connected to the housing by a positive fit or by its material, and/or may be of an integral design.

An activation cam6projects transversely to the direction of movement of the needle guard3into the groove7. The activation cam6has an inclined region or convex shape at its surface pointing or extending in the proximal (rear or rearward) direction, which pushes the lock element4out transversely to the direction of movement of the needle guard3, in this instance downward, as the needle guard3moves in the proximal direction. The needle guard3also forms a complementary lock element5, which is laterally disposed outside of the alignment directed in the longitudinal direction and extending through the activation cam6. The activation cam6has a curved shape in the distal direction and the activation cam6extends sufficiently far in a direction that it at least partially covers the complementary lock element5, such that the lock element4cannot engage with the complementary lock element5when it is moved past the activation cam6and springs back in the direction from which the lock element4was moved out from the activation cam6. In this state, the needle tip extends at least far enough out of the distal end of the needle guard3so that the needle tip at least touches the piercing point of the patient. This may be regarded and/or referred to as the activation position or injection position. If desired, the needle guard3can now be moved even farther in the proximal direction so that the needle1pierces the tissue even deeper. Once the injection has terminated, the needle1is pulled out of the body, as a result of which the spring9pushes the needle guard3in the distal direction. As this happens, the lock element4, which is now disposed distally of the activation cam6, is pushed into the complementary lock element5by the concavely oblique shape of the driving surface of the activation cam6pointing in the distal direction. In this position, the needle guard3is locked so that it is not able to move axially relative to the housing and if the needle safety module is used correctly can no longer be released.

Since the needle guard3is moved by a measured distance along the needle longitudinal axis in the end position in which the lock element4is disposed in the complementary lock element5, an annular marking20extending around the circumference of the needle guard3in the region of the distal end of the housing2disappears in the housing. In particular, the marking20is covered by a housing2. As a result the user of the device is able to tell that the needle safety module has been used and can not be used again. For example, an annular, circumferentially extending stripe of an appropriate colour such as green is used for the marking20, and the stripe is preferably of a width and assumes an appropriate position such that the marking20is completely covered by the housing2when the needle guard3is in the end position.

The embodiment of the needle safety module illustrated inFIGS. 2 to 3Fhas a modification compared with the embodiment illustrated inFIG. 1. The explanations given in connection with the embodiment ofFIG. 1therefore essentially apply to the embodiment illustrated inFIGS. 2 and 3. However, unlike the embodiment illustrated inFIG. 1, the needle guard3depicted inFIGS. 2 to 3Fhas a first groove7and a second groove8. The first groove7has a groove base along which the lock element4slides as it is moved transversely by the lock cam6as the needle guard3moves out of the initial position in the proximal direction. In a position in which the lock element4has been moved past the lock cam6, the lock element4latches in the second groove8. As illustrated here, the second groove8may be an orifice or a groove8which also has a groove base, in which case the distance of the groove base of the first groove7from the needle longitudinal axis is shorter than the distance of the groove base of the second groove8from the needle longitudinal axis. In other words, there is a height offset between the first groove7and the second groove8, which prevents the lock element4from sliding back from the second groove8into the first groove7.

FIGS. 3A to 3Fillustrate the needle guard3in section and the different positions of the lock element4, which is illustrated without an arm and is shown only by the part which locates with the pawl system (which may be thought of as comprising elements5,6,7,8).FIG. 3aillustrates the initial position. The lock element4is axially aligned with the complementary lock element5. Due to the resilient design of the lock element4on the arm, not illustrated, the lock element4tends to latch in the complementary lock element5due to its elasticity, provided it is in the corresponding axial position. In the arrangement illustrated inFIG. 3B, the needle guard3has moved in the proximal direction, causing the lock element4to be deflected transversely to the direction of movement due to the curved switching surface of the activation cam6pointing in the proximal direction. The lock element4may also slide along the groove base of the first groove7. InFIG. 3C, the lock element4is illustrated in a position in which it has moved past the activation cam6. This position may be termed the trigger or activation position which, to a certain extent, represents a special situation of the injection position because it is assumed that the needle tip (not illustrated) has made contact with the body tissue of the patient. When the lock element4is in the position illustrated inFIG. 3C, having moved past the activation cam6, the lock element4has moved out of the first groove7and latched in the second groove8due to its resiliently elastic design. As a result of the shoulder78, the lock element4is no longer able to move back into the first groove7.

FIG. 3Dillustrates the lock element4and the needle guard3in a position in which the needle is projecting out of the distal end of the needle guard3by its full injection length.

InFIG. 3E, the lock element4and the needle guard3are illustrated in a position in which the needle guard3has been moved back in the distal direction out of the injection position or trigger position. As this happens, the lock element4is able to move between the end of the activation cam6inclined in the distal direction and the complementary lock element5, which was not possible during the movement from the position illustrated inFIG. 3Binto the position illustrated inFIG. 3C. When the needle guard3is moved out of the position illustrated inFIG. 3Eeven farther in the distal direction, the lock element4latches in or with the complementary lock element5because of the resilient design of the lock element4. In the position illustrated inFIG. 3F, the needle guard3is locked so that it is not able to move axially.

FIGS. 4 to 6Eillustrate another embodiment of a needle safety module in accordance with the present invention. The needle safety module comprises a housing2, in which a needle holder11, which will be described in more detail with reference toFIG. 5, is accommodated by a positive catch connection. The needle holder11is used to mount an injection needle1so that it can not move axially. The needle1may be cast into the needle holder11by an injection moulding process. The needle holder11has two cams5a,5bjoined to it with a recess formed between the cams5aand5b, which serves as the complementary lock element5. The cams5aand5bare resiliently and, in some embodiments, integrally joined to the needle holder11via an arm. The housing2is fitted with a needle guard3, which is able to move axially relative to the housing2. The needle safety module illustrated inFIG. 4shows the needle guard3in an initial position.

As may be seen from the perspective view illustrated inFIG. 5, the cams5aand5bare set at an angle with respect to the needle longitudinal axis. This angular set enables a transverse movement of the complementary lock element5or cams5aand5bin specific positions, as will be explained with reference toFIGS. 6A to 6E.FIG. 6Ais a view of a needle guard3from the end. The needle guard3has four recesses in its external circumferential surface in which elements of the housing2are able to locate, thereby establishing an anti-rotation lock between the needle guard3and the housing2. The needle guard3also has four inwardly directed projections, which serve as a stop for a spring element which is supported on the four projections of the needle guard3on the one hand and on the proximal end of the needle holder11on the other.

The needle guard3also has a first groove7and a second groove8, each of which has a groove base, and the two groove bases are inclined at a tangent in the same direction. In other words, the groove bases of grooves7and8are inclined at a rolling angle about the longitudinal axis of the needle guard3. A height offset78is formed due to the angular set between the grooves7and8. The purpose of the offset78is to prevent the complementary lock element5from moving out of groove8into groove7. Projecting out from the groove base of groove7into the interior of the guard is an activation cam6. The activation cam6has a “saw-tooth” shape and its flatter side points in the proximal direction of the needle guard3. Projecting out from the groove base of the second groove8is a lock element4directed toward the interior of the guard3. The lock element4has a respective stop surface pointing in the proximal and in the distal direction which can not be overcome. The lock element4tapers across the width of the second groove8from the edge78to its oppositely lying edge.

FIGS. 4 and 6Billustrate the positions of the activation cam6, the complementary lock element5, including the cams5aand5b, and the lock element4with the needle guard3in an initial position. At least the cam5bis disposed proximally of the activation cam6. The complementary lock element5is disposed in the first groove7. As the needle guard3moves in the proximal direction, the complementary lock element5, in particular the cam5b, is moved past the activation cam6and assumes the position illustrated inFIG. 6C. During the latter movement, the complementary lock element5, including the cams5aand5b, lifts out of the groove base of the first groove7. Once the complementary lock element5has moved past the activation cam6, it moves back into contact with the groove base of the first groove7. Due to the saw-tooth design of the locking cam6, in particular its stop surfaces pointing in the distal direction, the complementary lock element5, in particular the cam5b, can no longer be moved back across the activation cam6into the initial position.

FIG. 6Eillustrates the position of the complementary lock element5relative to the needle guard3in a position in which the needle has been extracted from the distal end of the needle guard by approximately its full injection length.

When the needle is pulled out of the tissue, the needle guard3is pushed back in the distal direction by the spring (not illustrated), causing the complementary lock element5to assume again the position illustrated inFIG. 6C.

When the needle guard3is moved out of the position illustrated inFIG. 6Ceven farther in the distal direction, for example by the spring, the complementary lock element5assumes the position illustrated inFIG. 6E. In other words, the complementary lock element5and the lock element4latch. In this position, the needle guard3can no longer be moved relative to the housing2because any movement of the complementary lock element5from the second groove8into the first groove7is prevented by the offset78and the stops of the lock element4pointing in the distal and proximal direction. The fact that the activation cam6is set at an angle with respect to the longitudinal axis and the lock element4is set at an angle with respect to the longitudinal axis, in conjunction with the spring force of the spring acting on the needle guard3, causes the transverse movement of the complementary lock element5from the position illustrated inFIG. 6Cinto the position illustrated inFIG. 6E.

FIG. 7illustrates an alternative embodiment of an activation cam6and a complementary lock element5, comprising the cams5aand5b. The advantage of this embodiment is that the activation cam6simultaneously assumes the function of the lock element4. The needle safety module illustrated inFIGS. 4 to 6may be provided with the activation cam6and the complementary lock element5illustrated inFIG. 7. With an embodiment of this type, the groove8or offset78illustrated inFIG. 6band the lock element4are dispensed with.

The activation cam is split into two parts and has a front part6apointing in the proximal direction which extends at an angle in the distal direction (FIG. 7B) so that a complementary lock element5a with co-operating complementary angled region (cam5a) can be pushed sideways past the activation cam (which may be thought of as comprising elements6;4;6a). The part6aof the activation cam extends out from the base groove of the groove7by a shorter height than the remaining part of the activation cam (FIG. 7A).

As illustrated inFIGS. 7Eto H, when the needle guard3is moved out of the initial position in the proximal direction, the complementary lock element5is pushed sideways past the activation cam (FIG. G) until it has moved past the complementary lock element5and assumes a lateral position in which it was disposed in its initial position (FIG. H). The needle guard3can then be moved farther in the proximal direction, and the needle1can be injected. When the needle1has been pulled out of the body, the needle guard3is pushed in the distal direction by the spring9. Due to the design of the surface of the cam5bpointing in the proximal direction of the complementary lock element5(FIG. 7C), namely a surface inclined at an angle with respect to the groove base of the groove7, the complementary lock element5is able to move across the activation cam6to the degree that it latches with the other part of the activation cam projecting out from the groove base. As a result, an axial movement of the complementary lock element5and the activation cam, which also acts as a lock element, is no longer possible. Consequently, a movement of the needle guard3relative to the housing2is also no longer possible. The needle safety module is therefore finally locked.

FIGS. 8 to 11illustrate another embodiment of a needle module in accordance with the present invention, in which the needle guard3is disposed in end position distally of its initial position. The needle safety module has a housing2, a needle guard3which is able to move axially relative to the housing2and a spring9, which is supported on the needle holder11and the distal end of the needle guard3and pushes the needle guard3in the distal direction. The needle holder11is pressed into the housing2and holds an injection needle1. The housing2has fixing means12by which the housing2can be attached to an injection device. The housing has a complementary lock element5, in which the lock element4provided on the needle guard3is able to latch so that a movement of the needle guard3relative to the housing2is blocked when the lock element4is latched in the complementary lock element5. In the arrangements illustrated inFIGS. 8 and 9, the needle guard3is in an initial position, namely a position in which the lock element4has still not latched in the complementary lock element5. The needle safety module also has a locking element10, which extends through an orifice15(FIG. 11) in the needle guard3and locates in a shoulder formed by the housing2so that the needle guard3can not be moved any farther in the distal direction. The locking element10is integrally joined to an annular base element10avia resilient arm10b(FIG. 10). The annular base element10asits loosely on the end face of the needle holder11pointing in the distal direction.

The locking element10also has a driving surface10cextending at an angle with respect to the direction of movement of the needle guard3. This driving surface10cco-operates with a matching inclined driving surface3aof the needle guard3so that a movement of the needle guard3in the distal direction causes the locking element10to move transversely to the direction of movement of the needle guard3. As a result of this transverse movement of the locking element10caused by the needle guard3moving in the distal direction, the engagement of the lugs10dof the locking element10laterally engaging round the driving surface10cis released. In some preferred embodiments, at the instant the engagement of the locking element10with the housing2is released, the needle tip extends far enough out of the distal end that it at least touches the injection point of the patient. The needle guard3can now be moved as far as needed in the proximal direction to enable the needle to effect a piercing movement. When the needle guard has been moved out of this position back in the distal direction, the locking element10latches in the groove13, as a result of which the locking element10is no longer able to effect an axial movement relative to the needle guard3, at least in one direction, so that when the needle guard3is moved farther in the distal direction, the locking element10, including the annular base element10aand the arms10b, is also driven in the distal direction. At the end of the movement in the distal direction, the lock element4latches in the complementary lock element5, causing the needle guard3to be locked so that it can not be moved axially relative to the housing2.