Abstract:
A needle protection device detachably fixed to an injection appliance includes a needle, a needle holder from which a needle injection section of the needle projects distally and a needle connection section of the needle projects proximally, a distal needle protection element connected to the needle holder movable in the distal direction from a release position to a protection position and arranged behind the needle injection section in the release position and overlapping the needle injection section and distal end of the injection needle in the protection position, a proximal needle protection element connected to the needle holder movable from a release position and arranged behind the needle connection section into a protection position and overlapping the needle connection section and proximal end of the injection needle, and a blocking device which blocks movement of the proximal needle protection element from the protection position into the release position.

Description:
CROSS-REFERENCED RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/399,700, filed Mar. 6, 2009,issued as U.S. Pat. No. 8,052,653 on Nov. 8, 2011, which is a continuation of International Patent Application No. PCT/CH2007/000414 filed Aug. 22, 2007, which claims priority to German Patent Application No. DE 10 2006 042 233.3 filed Sep. 6, 2006, the entire contents of both of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The invention relates to devices for injecting, delivering, infusing, dispensing or administering a substance, and to methods of making and using such devices. More particularly, it relates to a needle guard device which is releasably attached to or can be attached to an injection device. The injection device may be used to administer medicaments, for example insulin, and for self-administration, i.e. by patients who administer the relevant medicament themselves. The injection device may be configured for repeated use and to allow the dose of product to be administered to be set or selected. More particularly, the injection device may be an injection device of the type used to treat diabetes or otherwise. 
     To prevent the risk of infections, needle guard devices have been developed which enable an injection device to be used only once. A needle guard device of this type is known from patent specification WO 01/91837 A1, for example. The injection needle extends through the needle holder and is fixedly secured by the needle holder. It has an injection portion extending beyond the needle holder in the distal direction and a connecting portion extending beyond the needle holder in the proximal direction. 
     SUMMARY 
     One object of the present invention is to provide needle guard devices that increase the level of safety which can be achieved by using such devices and to prevent injury due to piercing. 
     In one embodiment, the present invention comprises a needle guard which can be releasably attached to an injection device. In one embodiment, the needle guard comprises an injection needle and a needle holder holding the injection needle, from which the needle projects by a needle injection portion in the distal (front or forward) direction and from which the needle projects by a needle connecting portion in the proximal (rear) direction. The needle guard also has a distal needle guard for the needle injection portion which is connected to the needle holder so that it can move. The injection needle may extend through the needle holder and is fixedly secured by the needle holder. Alternatively, the needle injection portion and the needle connecting portion may also be separate needles, which are retained by the needle holder and connected to one another to establish a fluid flow. However, the needle holder may also incorporate the two needle portions in a single piece. 
     When administering the substance or product to be administered, the needle injection portion pierces the skin and/or tissue lying subcutaneously underneath. When a membrane is attached, providing a tight seal at a distal outlet of a reservoir filled with the product to be administered, the needle connecting portion pierces it. The distal needle guard is able to move in the distal direction relative to the needle holder from a released position as far as a guard position, such as by spring force. When the needle guard assumes the released position, the injection needle sits or rests with its needle injection portion beyond the needle guard in the distal direction. In the guard position, on the other hand, the needle guard overlaps the needle injection portion as far as and including a distal (forward or injection end) end of the injection needle. In the initial state prior to using the device for the first time, the needle guard may assume a distal initial position from which it can be moved into the released position. 
     In some embodiments, the distal needle guard is locked in the guard position so that it can not be moved into the released position again. The lock may be established automatically when the needle guard has reached the guard position, having moved in the distal direction. Apart from self-locking needle guard devices of this type, however, the present invention also generally relates to needle guard devices with a displaceable distal needle guard which does not lock after an injection. In such designs, the needle guard is primarily used to block the view to remove the fear of the injection needle for a user administering the product himself. 
     As provided herein, in some embodiments, the needle guard device comprises a proximal needle guard, which is displaceably connected to the needle holder. The proximal needle guard can be moved in the proximal direction out of a released position as far as a guard position. In the released position, the needle connecting portion extends beyond the proximal needle guard in the proximal direction. In the guard position, the proximal needle guard overlaps the needle connecting portion up to and including the proximal end of the injection needle. The needle guard device also has a lock mechanism for the proximal needle guard. As soon as the proximal needle guard has reached the guard position, having moved in the proximal direction, it is automatically locked by the lock mechanism so that it is no longer able to move back into the released position. Although needle guard devices with a distal guard are already known from the prior art, for example, from patent specification WO 01/91837 A1 mentioned above, as recognized herein, the needle connecting portion can also cause piercing injuries after the respective needle guard device has been used and the embodiments disclosed herein eliminate this risk via the other needle guard which automatically locks in a guard position after the needle guard device in accordance with the present invention has been used, i.e. as the injection device is removed or after it has been removed. 
     In some embodiments, the needle guard device has a fixing mechanism configured as a fixing sleeve to provide a releasable connection to the injection device. The fixing mechanism may co-operate with fixing means associated with or disposed externally on the injection pen. It may be a threaded or bayonet sleeve or a snap-fit, catch-fit or clip-on sleeve, for example. In such designs, the fixing device surrounds the needle connecting portion in a manner conventionally used for needle guard devices. However, the known fixing devices are usually so large in terms of their diameter that the user can easily reach the needle tip of the needle connecting portion with the finger and injure himself. The distal needle guard provided herein, however, is disposed closer to the needle connecting portion than with other fixing mechanisms, and the distance measured transversely to the needle connecting portion is short, such that the user does not come into contact with the proximal needle tip if he touches the proximal end of the proximal needle guard. As a result, the manufacturer also has greater freedom in terms of the design of the fixing mechanism because it offers an additional protective function compared with the other sleeve-shaped, fixing mechanisms, but in this case protecting against piercing injuries can be obtained by the proximal needle guard. 
     In some embodiments, a needle guard device in accordance with the present invention has a spring element, which biases the proximal needle guard in the proximal direction by a spring force. The spring element may be supported directly on the proximal needle guard but may also act on the needle guard via one or more intermediate elements. In such designs, when the needle guard device is removed from the injection device, the needle guard is moved into the guard position by spring force. In other variants, the same spring element also acts in the distal direction on the distal needle guard directly or via one or more intermediate elements. In further embodiments, the spring element is supported at one end on the distal needle guard and at the oppositely lying end on the proximal needle guard. Depending on its function, the spring element may be a compression spring, such as a helical spring. In alternative embodiments, the proximal needle guard is not moved into the guard position by spring force, but by a retaining mechanism comprising a retaining holder on the proximal needle guard and a retaining holder on the injection device or product reservoir, which automatically move into a retaining engagement when the needle guard device and injection device are connected, which causes the proximal needle guard to be moved from the released position into the guard position when the needle guard device is released. Once the proximal needle guard has assumed its guard position, the retaining engagement automatically releases when the needle guard device is substantially or completely detached from the injection device. 
     In some embodiments, the lock mechanism comprises at least two locking elements, a first locking element formed on the needle holder or, in the situation where the parts are separate, connected to the needle holder, and a second locking element formed on the proximal needle guard or, in the situation where the parts are separate, connected to the needle guard. At least one of the locking elements may be able to move transversely to the longitudinal direction of the injection needle against a resistant or rebounding spring force. The relevant locking element itself may be inflexible, i.e. rigid, and in such embodiments is biased by the rebounding spring force by a separate spring element. However, the relevant locking element may be elastic and may form an elastic bending beam. The rebounding spring force may be used to move the locking element into the locked engagement with the other locking element. The locked engagement may be achieved by an elastic snapping movement. In alternative embodiments, however, the lock mechanism may be provided in the form of only rigid locking elements, i.e. they are not flexible. This being the case, however, the locking elements may need to be moved into the locked engagement when the proximal needle guard moves into the guard position. In such embodiments, the lock mechanism may have one or more slide guides, by which the locking elements are forcibly guided relative to one another into the locked engagement. 
     In some embodiments, the second locking element formed on the proximal needle guard or connected to the needle guard may be guided outwardly from the needle guard and co-operate with the first locking element by gripping the needle guard device, but the proximal needle guard may extend through the needle holder in the distal or in the proximal direction, at least in the guard position. 
     In one embodiment, the proximal needle guard assumes a proximal (rearward) initial position prior to using the needle guard device, from which it is moved into the released position as the needle guard device is connected to the injection device. In a second embodiment, the proximal needle guard is already in the released position in the state in which the needle guard device is sold. In both embodiments, the needle guard device comprises an unlocking element. In the first embodiment, the unlocking element co-operates with the at least one locking element, which can be displaced transversely to the longitudinal direction of the injection device so that the locked engagement can be established during the movement out of the proximal initial position into the released position because the unlocking element is engaged with the transversely moving locking element, which may also include the situation in which it is engaged with the first and the second locking element in order to prevent the locked engagement. During the course of the injection, such as during piercing by the needle injection portion or as the needle injection portion is being pulled out of or has been pulled out of the tissue, the engagement between the unlocking element and locking element is automatically released so that the locking elements are able to move into the locked engagement when the needle guard device is detached from the injection device. In the second embodiment, during piercing by the injection needle, the unlocking element is moved out of an unlocking position, in which it prevents the proximal needle guard from moving in the proximal direction, into a neutral position in which it permits such a movement and hence a movement into the guard position. The unlocking element of the second embodiment may be rotatable and connectable to the needle holder so as to be rotatable about the injection needle. 
     The unlocking elements of both embodiments may be coupled with the distal needle guard or may be automatically coupled with the distal needle guard during piercing or as the injection needle is being pulled out of the tissue. In such designs, the distal needle guard causes the unlocking element to move out of the unlocking position into the neutral position via the coupling. The coupling may be a driving engagement by which the distal needle guard drives the unlocking element with it as far as the neutral position as it moves in the distal direction, i.e. during removal from the tissue. Alternatively, the slide guide may form the coupling, in which case the slide guide converts the piercing movement or the movement of extracting the distal needle guard into the movement of the unlocking element out of the unlocking position into the neutral position. As a result, the slide guide enables a linear piercing movement or extraction movement of the distal needle guard to be converted into a rotating movement of the unlocking element, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view onto a distal end face of an example of a needle guard device according to a first embodiment in accordance with the present invention; 
         FIG. 2  shows the needle guard device in a longitudinal section A-A; 
         FIG. 3  shows the needle guard device in a longitudinal section B-B; 
         FIG. 4  shows the needle guard device in a longitudinal section C-C; 
         FIG. 5  illustrates components of the needle guard device aligned along a longitudinal axis of the needle guard device; 
         FIGS. 6A-D  show a fixing and guide mechanism of the needle guard device at a front view, along longitudinal sections A-A and B-B and a perspective view along a longitudinal axis of the fixing guide mechanism; 
         FIG. 7  shows a distal needle guard of the needle guard device; 
         FIG. 8  shows an unlocking element of the needle guard device; 
         FIG. 9  is a perspective diagram showing a needle holder of the needle guard device; 
         FIG. 10  shows the needle holder in longitudinal section; 
         FIG. 11  is a perspective diagram showing a proximal needle guard of the needle guard device; 
         FIG. 12  shows the proximal needle guard in longitudinal section; 
         FIG. 13  shows an embodiment of a lock mechanism of the needle guard device, with the proximal needle guard in a proximal initial position; 
         FIG. 14  shows the lock mechanism, with the proximal needle guard in a releasing position; 
         FIG. 15  shows the lock mechanism, with the proximal needle guard in a guard position; 
         FIG. 16  is a diagram on a larger scale showing the lock mechanism, with the proximal needle guard in two different positions; 
         FIG. 17  shows components of a needle guard device based on a second embodiment in accordance with the present invention; 
         FIG. 18  shows the distal needle guard of the second embodiment; 
         FIG. 19  is a perspective diagram showing a needle holder of the second embodiment; 
         FIG. 20  shows the needle holder of the second embodiment in longitudinal section; 
         FIG. 21  is a perspective diagram showing an unlocking element of the second embodiment; 
         FIG. 22  is a plan view in the distal direction showing the unlocking element of the second embodiment; 
         FIG. 23  shows a proximal needle guard of the second embodiment; 
         FIG. 24  shows a lock mechanism of the second embodiment in an initial state prior to an injection; 
         FIG. 25  shows the lock mechanism of the second embodiment in an end state after an injection; 
         FIG. 26  shows the needle guard device of the second embodiment in the initial state; 
         FIG. 27  shows the needle guard device of the second embodiment in a state during an injection; and 
         FIG. 28  shows the needle guard device of the second embodiment in the end state. 
     
    
    
     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. Generally, unless otherwise indicated, relative positional or orientational terms (e.g., upwardly, downwardly, above, below, etc.) are intended to be descriptive, not limiting. 
       FIG. 1  is a plan view onto a distal end face illustrating a needle guard device based on a first embodiment of the present invention. Three longitudinal planes are indicated, A-A, B-B and C-C. 
       FIG. 2  is a view in longitudinal section A-A indicated in  FIG. 1 , showing the needle guard device based on the first embodiment.  FIG. 3  is a view of the needle guard in longitudinal section B-B and  FIG. 4  illustrates longitudinal section C-C. 
       FIGS. 1 to 4  illustrate the needle guard device in an initial state, which it assumes or is in prior to being used for the first time. In this state, the needle guard device may be supplied to the user in a suitable sterile packaging, not illustrated. The needle guard device comprises an injection needle  1  in the form a straight, hollow cannula and a needle holder  2 , which fixedly retains the injection needle  1  in a middle needle portion so that the injection needle  1  is not able to move axially, i.e. in the longitudinal direction L, and is also not able to rotate. The needle holder  2  has a base  9  and a retaining region  10 , which projects centrally out from the base  9  and holds the injection needle  1 . The injection needle  1  extends through the retaining region  10  of the needle holder  2 . It projects beyond the retaining region  10  by an injection portion  1   a  in the distal direction and by a connecting portion  1   b  in the proximal direction. 
     The needle holder  2  is inserted in a sleeve-shaped fixing and guide mechanism and secured so that it is not able to move. The needle holder  2  divides the fixing and guide mechanism into a proximal fixing portion  3  and a distal guide portion  4 . The needle injection portion  1   a  extends beyond the guide portion  4  in the distal direction by a length suitable for administering subcutaneous injections. The fixing portion  3  constitutes a fixing mechanism to provide a releasable attachment to a distal end of an injection device. The fixing mechanism may have one or more catch elements to provide a catch connection to the injection device. Alternatively, the fixing mechanism of the needle guard device may also have a screw thread or a bayonet fitting. The fixing portion  3  surrounds the needle connecting portion  1   b  and extends beyond it in the proximal direction. The guide portion  4  acts as a non-rotatable, axial guide for a distal needle guard  5 , which in the initial state assumes a distal initial position relative to the needle holder  2  in which it extends beyond the guide portion  4  and distal tip of the injection needle  1 . The distal needle guard  5  is a sleeve-shaped body extending circumferentially around the injection portion  1   a  and simultaneously also acts as a visual guard so that the user is not able to see the injection portion  1   a . The distal needle guard  5  is biased by a spring element  6  by spring force acting in the distal direction. In the distal initial position, the distal needle guard  5  is retained against the force of the spring element  6  relative to the guide portion  4  by an unlocking element  8 . 
       FIGS. 5 to 8  illustrate how the distal needle guard  5  co-operates with the unlocking element  8  and the guide portion  4 . In  FIG. 5 , the components of the needle guard device are aligned one after the other along its central longitudinal axis L in the order in which they are assembled. The injection needle  1  is shown released from the needle holder  2  but may already be fixedly connected to the needle holder  2  at the time of assembly. 
       FIGS. 6A-D  shows the fixing and guide mechanism (which may be thought of as comprising elements  3 ,  4 ) from a front view ( FIG. 6A ), two longitudinal sections A-A ( FIG. 6B ) and B-B ( FIG. 6C ) and a perspective view ( FIG. 4D ). The fixing and guide mechanism has two recesses  4   a  in its guide portion  4  at the distal end in an internal face extending circumferentially about the longitudinal axis L. At their proximal end, the recesses  4   a  merge into the internal face via a steep shoulder. The two shoulders each form a translation stop  4   c  pointing in the distal direction. Disposed to the side of the recesses  4   a  are respective axially extending guides  4   b  to ensure that the distal needle guard  5  is guided in a straight line. Two other recesses  4   d  are provided at the distal end of the guide portion  4  in the same internal face, which are offset from the recesses  4   a  on the circumference of the internal face by 90° in each case. The recesses  4   d  each merge into the internal face via a steep shoulder at their distal end. The two shoulders each form a translation stop  4   e  pointing in the proximal direction. 
       FIG. 7  shows the distal needle guard  5 . The distal needle guard  5  has axial guides  5   b , which co-operate with the guides  4   b  of the guide portion  4  and with them guide the distal needle guard  5  linearly but prevent it from rotating. Disposed at the proximal end of the distal needle guard  5 , two orifices O are provided in its casing, offset from one another in the circumferential direction by 180°. A projection  5   c  projects respectively in the proximal direction into the orifices O, which axially lengthens the casing of the distal needle guard  5  in the respective orifice. The internal faces of the projections  5   b  are outwardly inclined in the proximal direction towards free ends of the projections  5   b  and, in the embodiment illustrated as an example, each has a constant inclination. They each form a ramp in co-operation with the unlocking element  8 . The distal needle guard  5  has two locking element elements  5   a  on its proximal end offset from one another in the circumferential direction by 180°, which are provided in the form of resilient lugs in the embodiment illustrated as an example. The locking elements  5   a  are outwardly inclined in the proximal direction. Finally, two locating elements  5   d  in the form of outwardly projecting cams are provided on the external circumference of the distal needle guard  5 , likewise at its proximal end offset from one another by 180° in the circumferential direction. 
       FIG. 8  illustrates an embodiment of the unlocking element  8 . The unlocking element  8  has an annular base  22  at its proximal end. Projecting out from the base  22  in the distal direction are two fingers  23 , each of which has a projection  24  extending outwardly from its distal end. When the needle guard device is in the initial state, the projections  24  extend through the orifices of the distal needle guard  5 , as illustrated in  FIG. 4 , and hold the distal needle guard  5  in its distal initial position against the spring force of the spring element  6  due to the spring element  6  pushing the outer ends of the projections  24  into abutment with contact surfaces of the guide portion  4 . Like the projections  5   c  of the distal needle guard  5 , the projections  24  are inclined to form a ramp shape and their inclination is adapted to that of the projections  5   c.    
     As may be seen from  FIGS. 2 to 4 , not only does the needle guard device have the distal needle guard  5 , it also has a proximal needle guard  7  for the connecting portion  1   b  of the injection needle  1 . The unlocking element  8  co-operates with both the distal needle guard  5  and the proximal needle guard  7 . In co-operation with the distal needle guard  5 , it fulfils the described locking function. In co-operation with the proximal needle guard  7 , it fulfils an unlocking function because in its initial position illustrated in  FIGS. 2 to 4 , it prevents a movement of the proximal needle guard  7  in the distal direction from being blocked. To enable co-operation with the proximal needle guard  7 , two axially extending recesses formed as an axially extending track  25  are provided in the internal face of the base  22  of the unlocking element  8  offset from one another in the circumferential direction by 180°, in which the proximal needle guard  7  locates in its initial position. 
       FIGS. 9 and 10  illustrate the needle holder  2  and  FIGS. 11 and 12  illustrate the proximal needle guard  7 . The proximal needle guard  7  has an annular base  14  at its proximal end and locking elements  15  projecting out from the base  14  in the distal direction. The locking elements  15  are finger-shaped or rod-shaped. In the embodiment illustrated as an example, these are two locking elements which project out from a distal end face of the base  14  and are offset from one another by 180° in the circumferential direction about the longitudinal axis L so that they enclose the needle connecting portion  1   b  between them when the proximal needle guard  7  is in the proximal initial position. The base  14  has a central passage P for the needle connecting portion  1   b.    
     Disposed in a distal portion of the proximal needle guard  7 , the locking elements  15  have several projections, each extending outwards from the locking elements, in this example three projections  16 ,  17  and  18 . The locking elements  15  also each have a support  21  for the spring element  6 . The supports  21  are formed by projections extending radially inwardly toward one another at the distal ends of the locking elements  15 . The spring element  6  is supported on the proximal needle guard  7  in the proximal direction by means of the supports  21 , in other words is clamped or held between the distal needle guard  5  and the proximal needle guard  7 . 
     In the assembled state, the base  14  of the proximal needle guard  7  is disposed proximally of the base  9  of the needle holder  2  and the rod-shaped or finger-shaped locking elements  15  extend in the distal direction through two passages  11  formed in the base  9  of the needle holder  2 . In the proximal initial position, the distal projections  16  absorb the force of the spring element  6 . To this end, the projections  16  respectively form a stop pointing in the proximal direction which is pushed by the spring element  6  against a complementary stop  13  ( FIG. 10 ) of the needle holder  2 , which is formed by the base  9  of the needle holder  2  in the embodiment illustrated as an example. The projection  17  acts as another stop  20  pointing in the proximal direction. The projection  18  acts as yet another stop  19  but pointing in the distal direction. 
       FIGS. 13 ,  14  and  15  illustrate the different positions which the proximal needle guard  7  assumes relative to the needle holder  2  when the needle guard device is connected to the injection device and when detached from the injection device again after an injection. In  FIG. 13 , the proximal needle guard  7  has assumed its proximal initial position. It can be moved from the initial position against the force of the spring element  6  relative to the needle holder  2  and to the unlocking element  8  disposed in an unlocking position as far as a releasing position illustrated in  FIG. 14 , in which the needle connecting portion  1   b  extends beyond the proximal needle guard  7  in the proximal direction. In  FIG. 15 , the proximal needle guard  7  has assumed a guard position in which it is locked relative to the needle holder  2  so that it can not be moved out of the guard position back into the releasing position. To produce the lock, the needle holder  2  and the proximal needle guard  7  form a lock mechanism with locking elements in a locked engagement, namely on the two locking elements  15  of the proximal needle guard  7  and the base  9  of the needle holder  2  acting as a locking element. A result, the proximal needle guard  7  can be moved into the releasing position once only, namely by a force expended on the proximal needle guard  7  in the distal direction, and automatically moves due to the spring force of the spring element  6 , as the external force decreases, back in the proximal direction as far as the locked guard position. In the guard position, it extends beyond the distal tip of the needle connecting portion  1   b  in the distal direction and thus protects the user against injuries caused by piercing. In the embodiment illustrated as an example, a particularly reliable guarding action is provided due to the annular base  14  of the proximal needle guard  7 , the central passage of which is so narrow that the connecting needle is able to fit through the passage when attached to the injection device but the user cannot reach the distal needle tip through the passage. 
       FIG. 16  illustrates two states of the components which co-operate to move the proximal needle guard  7 . In the left-hand half of  FIG. 16 , the proximal needle guard  7  has assumed the distal initial position and in the right-hand half, the locked guard position. The left-hand half corresponds to the state illustrated in  FIGS. 2 to 4  and  FIG. 13  and the right-hand half of  FIG. 16  corresponds to the state illustrated in  FIG. 15 . 
     In the initial position, the projections  16  hold the proximal needle guard  7  on the needle holder  2 . The projections  17  taper in an arrow shape in the distal direction whilst the projections  18  taper in an arrow shape in the proximal direction. The stops  19  and  20  of the projections  17  and  18  are disposed axially facing one another. When the needle guard device is attached to an injection device by the fixing portion  3 , for example is screwed on or clipped on, the proximal needle guard  7  moves into contact with the distal end of the injection device and is pushed in the distal direction against the force of the spring element  6  during the attachment operation. During this movement, the projections  17  slide by their arrow-shaped distal faces through the passages  11  of the needle holder  2  so that the locking elements  15  are bent elastically inward. As soon as the projections  17  have moved through the passages  11 , they move into contact with the axial guide tracks  25  of the unlocking element  8 . The locking elements  15  thus remain in the bent state, for which purpose the passages  11  offer a way of axially extending the guide tracks  25 . The projections  17  extend farther outward than the following projections  18  which now move into the region of the passages  11 . The extra distance of the projections  17  measured transversely to the longitudinal axis L is long enough for the projections  20  in contact with the guide tracks  25  to hold the locking elements  15  far enough away from the outer edge of the passages  11  to enable the projections  18  to be moved in the distal direction, likewise through the passages  11 . Once the projections  18  have also moved through the passages  11 , the proximal needle guard  7  moves farther in the distal direction due to the contact with the injection device until the proximal needle guard  7  assumes the releasing position illustrated in  FIG. 14 , once the connection to the injection device is established. At the same time as the injection device is attached, the needle connecting portion  1   b  pierces a sealing membrane on a distal end of a medicament reservoir and thus establishes a flow connection between the medicament reservoir and the proximal tip of the needle injection portion  1   a.    
     When the needle guard device is detached from the injection device and pressure on the proximal needle guard  7  is thus released, the spring element  6  pushes the proximal needle guard  7  in the proximal direction. The proximal projections  18  firstly move into contact with the base  9  forming the locking element of the needle holder  2  so that the locking elements  15  are bent elastically inward again and the passages  11  are able to move in the proximal direction. As illustrated in  FIG. 16 , the guide track  25  of the unlocking element  8  may be sufficiently long in the axial direction to enable the projections  18  extending radially outward the farthest to pass the unlocking element  8  during the movement of the proximal needle guard  7  into the guard position. Alternatively, if the guide tracks  25  are short, as is the case with the exemplary unlocking element illustrated in  FIGS. 8-15 , the projections  18  are rounded at their outer ends or may be inclined, as in the embodiment illustrated as an example in  FIG. 16  and also in  FIGS. 12 and 14 . In the end state after use illustrated in the right-hand half of  FIG. 16 , the projections  18  with their respective stop  19  in co-operation with the base or locking element  9  prevent the proximal needle guard  7  from being able to move in the distal direction again relative to the needle holder  2 . 
     According to some embodiments, the needle guard device may be used as follows. The user attaches the needle guard device in the initial state illustrated in  FIGS. 2 to 4  to an injection device by connecting the fixing portion  3  to the distal end of the injection device. During the connection process, the injection device pushes in the distal direction against the proximal needle guard  7 , causing the latter to move into the releasing position illustrated in  FIG. 14 . At the same time, the injection needle  1  pierces the sealing membrane of the medicament reservoir in the region of its connecting portion  1   b  and establishes the flow connection to the proximal needle tip. When the needle guard device is attached to the injection device, the spring element  6  pushes the proximal needle guard  7  loosely against a point on the distal end of the injection device, for example against a terminal edge of the device or medicament reservoir. The distal needle guard  5  extends with its locking element  5   a  ( FIG. 7 ) into the guide portion  4  so that the locking elements  5   a  are not able to fulfil any locking function in this state and the distal needle guard  5  is able to move freely against the force of the spring element  6  in the proximal direction. 
     For the actual injection, the user then places the injection device on the desired injection point on the skin by the distal end, which is now formed by the distal needle guard  5 , and moves the injection device in the distal direction relative to the distal needle guard  5 . The distal needle guard  5  moves under the pressing force and against the force of the spring element  6  in the proximal direction deeper into the guide portion  4 . Simultaneously at the start of this movement, the ramp-shaped projections  5   c  of the distal needle guard  5  ( FIG. 7 ) slide across the adapted ramp-shaped projections  24  of the unlocking element  8  ( FIG. 8 ) so that its fingers  23  are elastically bent in the direction towards the central longitudinal axis L. During the remaining movement of the distal needle guard  5  in the proximal direction, the projections  24  slide in the axial direction across the internal face of the distal needle guard  5 . During this sliding movement, the fingers  23  of the unlocking element  8  are constantly bent elastically inwardly and push against the internal face of the distal needle guard  5  with an elastic force. The distal needle guard  5  moves completely into the guide portion  4  so that the injection needle  1  penetrates the skin and the subcutaneous tissue by its entire injection portion  1   a  extending out from the guide portion  4 . Full insertion of the distal needle guard  5  in the guide portion  4  may make the needle injection portion  1   a  as short as possible, but is not necessary. 
     After administering the medicament, the user moves the injection device away from the injection point so that the distal needle guard  5  moves back in the distal direction under the effect of the spring element  6 . Since the unlocking element  8  is connected to the distal needle guard  5  due to a non-positive connection via the projections  24  and the elastically bent fingers  23 , the distal needle guard  5  drives the unlocking element  8  with it as it moves in the distal direction so that the unlocking element  8  is lifted from the base  9  of the needle holder  2  and is moved relative to the proximal needle guard  7  into a neutral position. Since the projections  24  no longer extend through the distal needle guard  5 , the distal needle guard  5  moves beyond the distal initial position relative to the guide portion  4  in the distal direction. As soon as the locking elements  5   a  of the distal needle guard  5  have passed the stops  4   c  of the guide portion  4  ( FIG. 6 ), they snap outward into the recesses  4   a  and lock the distal needle guard  5  in a distal guard position, preventing a movement back in the proximal direction. The locating elements  5   d  move into the recesses  4   d  and co-operate with the stops  4   e  to hold the distal needle guard  5  on the guide portion  4 . Instead of the unlocking element  8  holding the projections  24  on the distal needle guard  5  by only a non-positive connection (e.g., frictional contact), the engagement could also be based on a positive connection, in which case the unlocking element  8  would latch with the distal needle guard  5  by the projections  24 . However, it the connection may be established early via the described non-positive connection. 
     To administer another injection, the user releases the needle guard device from the injection device with the distal needle guard  5  locked in its guard position. During the releasing process, the needle holder  2  moves in the distal direction relative to the injection device. The proximal needle guard  7  moves in the proximal direction relative to the needle holder  2  under the effect of the spring element  6 . As soon as the projections  18  of the proximal needle guard  7  have passed the passages  11  in the base  9 , i.e. the passages  11  of the locking element of the needle holder  2 , the locking elements  15  of the proximal needle guard  7  snap elastically outward. In this state illustrated in the right-hand half of  FIG. 16 , the stops  20  of the big projections  17  hold the proximal needle guard  7  on the needle holder  2  against the force of the spring element  6  and the stops  19  of the proximal projections co-operating with the complementary stops  12  of the needle holder  2  prevent the proximal needle guard  7  from being able to move in the distal direction again. The two stops  19  and  20  clamp the base  9  of the needle holder  2  in a close fit between them, and the clearance is ideally just enough to ensure that the short snapping or pivoting movement of the locking elements  15  is not prevented. However, the play may be greater, provided allowance is made for the proximal needle guard  7  to move axially. Such an ability to move should not be so great that the distal tip of the injection needle  1  is able to project out from the proximal needle guard  7 . 
       FIG. 17  shows a needle guard device based on a second embodiment with its components aligned longitudinally along a central longitudinal axis L in the order in which they are assembled. The needle guard device again comprises an injection needle  1  which is held by a needle holder  2 , as was the case with the embodiment illustrated as a first example, a fixing and guide mechanism  3 ,  4  for attaching the needle guard device to the distal end of an injection device and providing an axial guide for a distal needle guard  5  as well as a spring element  6 . As regards the way in which these components co-operate, the needle guard device of this embodiment corresponds to the embodiment illustrated as a first example. The fixing and guide mechanism is substantially similar to that described in connection with the first embodiment. The needle guard device also has a distal needle guard  27  and an unlocking element  30 , which differ in terms of function from the same components  7  and  8  of the first embodiment, due to the way in which they co-operate with the other components. 
       FIG. 18  illustrates the distal needle guard  5 ′ of the second embodiment. The distal needle guard  5 ′ of the second embodiment is missing the two orifices with the projections  5   c  but otherwise corresponds to the distal needle guard  5  of the first embodiment except that there is a smaller geometric deviation in the case of the locating elements  5   d ′. The locating elements  5   d ′ each have an inclination with respect to the longitudinal axis L on a side pointing in the circumferential direction about the longitudinal axis L so that the respective locating element  5   a ′ forms a ramp at the relevant side. 
       FIGS. 19 and 20  illustrate the needle holder  2 ′ of the second embodiment. The needle holder  2 ′ again has a base  9 ′ and a central retaining region  10 ′ for an injection needle  1  to be arranged in base  9 ′. As with the first embodiment, the base  9 ′ is provided with two passages  11 ′ through which the needle guard  27  can move in the proximal direction into its guard position and which also serve as a means of locking the needle guard  27  in the guard position. Projecting outward from the base  9 ′ in the distal direction adjacent to the retaining region  10 ′ are two projections  26   a  offset from one another by 180° in the circumferential direction about the longitudinal axis L, each of which is inclined on one side to form a ramp. Facing the ramp-shaped, inclined sides of the projections  26   a , a respective projection  26   b  also extends out from the base  9 ′ in the distal direction. The plane of the section illustrated in  FIG. 20  extends through the longitudinal axis L and through the gaps between each one of the projections  26   a  and the projection  26   b  facing the respective ramp. 
       FIG. 21  is a perspective view illustrating the unlocking element  30 .  FIG. 22  is a plan view showing a bottom face of the unlocking element  30 , i.e. a view in the distal direction. The unlocking element  30  is of a hollow cylindrical design. Two recesses  31  are provided in the casing of the unlocking element  30  offset from one another by 180° in the circumferential direction, which extend through the casing and form a guide track  32  inclined on one side in the circumferential direction for one of the locating elements  5   d ′ of the distal needle guard  5 ′. A respective projection  33  extends out from a distal edge of the unlocking element  30  into the respective recess  31 . The two recesses  31  are circumferentially framed by the casing of the unlocking element  30  and a recess  35  is provided respectively on the internal face of the casing distally in front of the guide tracks  32  which extends from the distal end of the unlocking element  30  continuously into the respective recess  31 . When the needle guard device is being assembled, the unlocking element  30  with its two recesses  35  is moved across the locating elements  5   d ′ of the distal needle guard  5 ′ so that the locating elements  5   d ′ move into the respective co-operating recess  31 . By turning the unlocking element  30 , likewise during the course of assembly, the locating elements  5   d ′ are then moved in the circumferential direction behind the respective projection  33  into the circumferential region  34  so that the locating elements  5   d ′ locate behind the distal edge of the unlocking element  30  in its circumferential regions  34  and hold the distal needle guard  5 ′ on the guide portion  4  against the force of the spring element  6  as a result. The unlocking element  30  is able to move in the distal direction so that it abuts with the guide portion  4  but is not able to move backward and forward between this abutting position and the base  9 ′ of the needle holder  2 ′, nor is it able to rotate relative to the needle holder  2 ′ about the longitudinal axis L. 
     The unlocking element  30  has an annular base  36  projecting radially inwardly on its bottom face at the proximal end of its casing and locating elements  37  projecting out from the base  36  in the proximal direction, in total two locating elements  37 , which are offset from one another by 180° in the circumferential direction. Two passages  38  for the proximal needle guard  27  are provided in the base  36 , offset from one another by 180° in the circumferential direction. 
       FIG. 23  illustrates the proximal needle guard  27 . The needle guard  27  has an annular base at a distal end and flexible legs or fingers projecting elastically out from the base in the direction towards the longitudinal axis L, which constitute the locking elements  28  of the needle guard  27 . A projection  29  is respectively formed on the external face of the locking elements  28 . The projections  29  taper in an arrow shape in the proximal direction and, as was the case with the projections  17  of the first embodiment, respectively form a stop of the needle guard  27  pointing in the distal direction. In this respect, reference may be made to the explanation given in connection with the first embodiment. 
       FIG. 24  illustrates the components of the lock mechanism of the second embodiment which co-operate to lock the needle guard  27 , with the needle guard  27  assuming a distal initial position which simultaneously also corresponds to the releasing position of the needle guard  27 . In the second embodiment, when the needle guard  27  is in the initial position, it already is completely behind the connecting portion  1   b  of the injection needle  1  in the distal direction. It is also behind the base  9 ′ of the needle holder  2 ′, i.e. the spring element  6  pushes the needle guard  27  towards the base  9 ′ in the proximal direction in the initial position. The locking elements  28  extend through the passages  38  of the unlocking element  30  ( FIG. 22 ). When the needle guard device is in the initial state, the passages  38  and the passages  11  of the needle holder  2 ′ are offset from one another in the circumferential direction. The locating elements  37  of the unlocking element  30  axially face the ramp-shaped sides of the projections  26   a  of the needle holder  2 ′. The spring element  6  holds the unlocking element  30  in the illustrated distal initial position illustrated in  FIG. 24  via the distal needle guard  5 ′ because the distal needle guard  5 ′ locates behind the unlocking element  30  in the circumferential regions  34  by its locating elements  5   d ′ and pulls it into the distal initial position, thereby moving it into abutment against the guide portion  4 . This initial state is also illustrated in  FIG. 26 . 
       FIG. 25  illustrates the components of the lock mechanism in the end state after the needle guard device has been used and with the needle guard  27  disposed in its proximal guard position.  FIG. 28  illustrates the needle guard device as a whole, likewise in its end state. 
     A description will be given below of how the needle guard device of the second embodiment works with reference to  FIGS. 26 to 28  but also with reference to the other drawings of  FIGS. 17 to 25 , particularly  FIGS. 24 and 25 . 
     The needle guard device is connected to the injection device in the initial state illustrated in  FIGS. 24 and 26 , for example screwed to it or clipped onto it. As this happens, the needle connecting portion  1   b  pierces the sealing membrane of the medicament reservoir. A movement of the needle guard  27  does not yet take place during the fitting process. 
     The user then pierces the skin through to the subcutaneous tissue at the desired injection point with the injection needle  1 . As this happens, the distal needle guard  5 ′ moves in the proximal direction relative to the needle holder  2 ′ so that, conversely, the needle injection portion  1   a  projects forward.  FIG. 27  illustrates the needle guard device in the piercing state whilst the medicament is being administered. 
     As the distal needle guard  5 ′ moves in the proximal direction, the locating elements  5   d ′ move along the respective associated guide track  32  of the unlocking element  30 . The inclination of the guide track  32  is selected so that there is no or practically no inhibiting effect. As a result of this guide engagement, the unlocking element  30  is rotated out of its angular position illustrated in  FIG. 24 , the unlocking position, into the angular position (neutral position) illustrated in  FIG. 25 . The rotating movement is superimposed by an axial translating movement during which the locating elements  37  of the unlocking element  30  slide on the ramp-shaped side of the respective co-operating projection  26   a . The translating and rotating movement is restricted by an abutting contact of the locating elements  37  and the projections  26   b . The unlocking element  30  drives the needle guard  27  with it during the rotating movement because the locking elements  28  extend through the passages  38 . As soon as the unlocking element  30  has reached its neutral position illustrated in  FIG. 25 , the passages  38  of the unlocking element  30  ( FIG. 22 ) overlap the passages  11 ′ of the needle holder  2 ′ ( FIGS. 19 and 20 ) to the degree that the locking elements  28  of the needle guard  27  are able to pass through the passages  11 ′ due to the force of the spring element  6 . The locking elements  28  are pushed by the spring element  6  against a point on the distal end of the injection device, for example a distal point of the device itself or the medicament reservoir. Once they have moved into the passages  11  of the needle holder  2 , the locking elements  28  prevent the unlocking element  30  from being able to turn back into its unlocking position ( FIG. 24 ). 
     When the injection needle  1  has been pulled out of the tissue and pressure has thus been relieved on the distal needle guard  5 ′, the spring element  6  moves the distal needle guard  5  in the distal direction. The position of the two projections  33  in the circumferential direction relative to the respective facing guide track  32  is selected so that the locating elements  5   d  are able to move into the recesses  35  as the distal needle guard  5  moves in the distal direction, thereby causing the distal needle guard  5 ′ to be finally released by the unlocking element  30 , and the locking elements  5   a ′ are able to move into the recesses  4   a  of the guide portion  4  ( FIG. 6 ), as was the case with the first embodiment, and lock the distal needle guard  5 ′ in its distal guard position to prevent it from moving in the proximal direction due to the lock engagement with the stops  4   c . As with the first embodiment, the locating elements  5   d  co-operate with the stops  4   e  ( FIG. 6 ) to ensure that the distal needle guard  5 ′ can not be completely extracted from the guide portion  4  in the distal direction. 
     The needle guard device is released from the injection device with the distal needle guard  5 ′ locked. The proximal needle guard  27  moves in the proximal direction relative to the needle holder  2 ′ into the guard position illustrated in  FIG. 25  and  FIG. 26  under the effect of the spring element  6 . In the guard position, the locking elements  28  extend beyond the tip of the needle connecting portion  1   b  in the proximal direction. The needle guard  27  is locked by a lock engagement between its projections  29  and the base  9 ′ of the needle holder  2 ′ to prevent a movement back in the distal direction. The needle guard  27  is supported by its annular base on the base  9 ′ of the needle holder  2 ′ in the proximal direction. 
     Embodiments of the present invention, including preferred embodiments, have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms and steps disclosed. The embodiments were chosen and described to provide the best illustration of the principles of the invention and the practical application thereof, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.