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 . fig1 and 2 provide a perspective diagram illustrating a needle guard device which can be fitted on a distal end of an injection device . the injection device may be of the type which enables a dose of an injectable product , for example insulin , to be set or selected , and the set dose to be dispensed on a repeated basis . it is also may be of the type that enables the dose to be re - set with each injection . the injection device may be an injection pen , of the type commonly used for self - administering medicaments , for example for the treatment of diabetes . the injection device is therefore designed for administering several injections for a longer service life . in some embodiments of the present invention , the needle guard device which surrounds an injection needle 1 for the injection device , on the other hand , is designed for a single injection only , i . e . for one - off use only . in readiness for use , it is attached to the distal end of the injection device , for example screwed onto it or , as in the case of the embodiments described as an example , push - fitted on it , and removed and disposed of after the injection . as mentioned above , the needle guard device comprises the injection needle 1 , a needle holder 2 and two sleeve - shaped structures , namely an outer sleeve 3 and an inner sleeve 6 , which form a needle guard telescope . the inner sleeve 6 is able to move axially relative to the outer sleeve 3 and relative to the injection needle 1 . fig2 illustrates the needle guard device in an initial state in which the inner sleeve 6 assumes a distal ( front or forward ) position relative to the outer sleeve 3 , in which it covers the injection needle 1 to beyond its needle tip and thus forms a view - blocking guard or cover . the inner sleeve 6 may , therefore , be thought of and / or referred to as needle guard 6 . the outer sleeve 3 serves to lock the needle guard 6 after the injection and may , therefore , be thought of and / or referred to as lock mechanism 3 . fig3 also illustrates the needle guard in the initial state . in addition to the longitudinal section , a cross - section is also illustrated . the position of the longitudinal section a - a is indicated in the diagram illustrating the cross - section . the lock mechanism 3 has a proximal fixing portion for attaching the needle guard device to an injection device . the needle holder 2 is inserted in the sleeve - shaped lock mechanism 3 and in the inserted state is connected to the lock mechanism 3 so that it is not able to move axially or in rotation about the longitudinal axis l . as far as the function of the lock mechanism 3 is concerned , namely protecting user or handlers from accidental sticks by the injection needle 1 , the lock mechanism 3 could be integrally molded with the needle holder 2 . when it comes to assembling the needle guard device , however , it is of advantage to manufacture it separately from the needle holder 2 . the needle holder 2 has a base 2 a , from the central region of which a retaining portion for the injection needle 1 projects in the distal direction . the longitudinal axis l of the injection needle 1 coincides with the proximal - distal axis . if , as in some preferred embodiment , the product or substance to be injected is conveyed by a reciprocating plunger , the axial direction advantageously coincides with the forward - drive direction of the plunger . the injection needle 1 is axially secured to the needle holder 2 in the retaining portion . the injection needle 1 extends through the retaining portion of the needle holder 2 . it extends in the proximal direction into a chamber of the fixing portion surrounded by the wall but sits behind a proximal edge of the wall . this chamber is sealed to render it sterile by a film , which is secured to the wall of the needle holder 2 at the proximal end . when the needle guard device is attached to the injection device , the film is destroyed and the proximal pointed end of the injection needle pierces a membrane sealing a distal end of a container filled with the product . as a result , during the process of attaching it to the injection device , a flow connection is simultaneously established between the injection needle 1 and the product container . toward its distal ( the front , forward or injection end ) end , the injection needle 1 has an injection portion incorporating the needle tip . the length of the injection needle is dimensioned for a subcutaneous injection . accordingly , the injection portion penetrates the skin and through the skin as far as a subcutaneous injection point . the injection portion extends in the proximal direction from the free needle tip as far as the axial level of the distal end of the lock mechanism 3 . in the initial state , the needle guard 6 assumes its distal - most position , which is predefined by the co - operation of a stop 4 of the lock mechanism 3 with a complementary stop 7 of the needle guard 6 . the stop 4 is formed by a shoulder projecting radially inward from the lock mechanism 3 and the complementary stop 7 is formed by a shoulder projecting radially outward from the needle guard 6 . the needle guard device also has a return element 9 , which is a mechanical compression spring in the embodiment illustrated as an example . the return element 9 exerts an elastic force acting on the needle guard 6 in the distal direction , by means of which it pushes the complementary stop 7 against the stop 4 . the return element 9 is axially supported on the lock mechanism 6 and the needle holder 2 . the needle guard device also has a locking member 10 for the needle guard 6 . the locking member 10 extends the retaining portion of the needle holder 2 in the distal direction . it has a cylindrical and , in the embodiment illustrated as an example , circular cylindrical external face , which lies opposite and faces a cylindrical and , in the embodiment illustrated as an example , circular internal face of the lock mechanism 3 disposed parallel at a distance apart . the external face of the locking member 10 and the internal face of the lock mechanism 3 radially bound an axially extending annular gap into which the needle guard 6 is able to move . the return element 9 is also disposed in the annular space . the internal and external surfaces mutually bounding the annular space guide the needle guard 6 during its movement in a sliding contact and also guide the return element 9 as it springs in and out in the exemplary embodiment . the external face of the locking member 10 forms a guide 12 for the needle guard 6 , which is a slide guide in the exemplary embodiment . the guide 12 forms a distal end portion of the locking member 10 . the guide 12 is a smooth surface extending circumferentially about the longitudinal axis l . it extends from the distal end of the locking member 10 in the proximal ( rearward ) direction and has a radially outward inclination . the locking member 10 becomes thicker at its external surface , namely from the distal end in the proximal direction , and falls abruptly away at a proximal end of the thicker region or wider region in a shoulder extending circumferentially about the longitudinal axis l except for an outer circular cylindrical portion of the locking member 10 . adjoining this portion , which is longer than the guide 12 , at the proximal end of the locking member 10 is a thicker end portion . the transition between the middle portion and the proximal end portion is also abrupt , in the form of a shoulder . the guide 12 curves continuously from its distal end to its proximal end , the shoulder 11 . in the exemplary embodiment , the inclination of the guide 12 becomes continuously more pronounced from its distal end in the proximal direction to close to the shoulder . the guide 12 may alternatively have a constant inclination or a gradually reducing inclination in the proximal direction . the needle guard 6 has two locating elements 8 , each of which co - operates with the guide 12 . in the section illustrated in fig3 , only one of the locating elements 8 is visible . the other locating element 8 is of the same shape as the one illustrated and also the same in terms of the way it co - operates with the guide 12 . the locating element 8 is provided in the form of a flexibly elastic lug extending out in the proximal direction from a root region in the casing of the needle guard 6 and has a shoulder projecting radially inward at its proximal end . the shoulder results in an inwardly projecting cam on the proximal end of the locating element 8 . this cam sits in a sliding contact with the guide 12 . when the needle guard 6 moves in the proximal direction , the cam slides on the guide 12 so that the locating element 8 is gradually bent elastically outward to an increasing degree , due to the inclined contour of the guide 12 . the shoulder at the proximal end of the guide 12 constitutes a complementary locating element 11 for each of the locating elements 8 . the locking member 10 is connected to the needle holder 2 sufficiently securely to prevent it from leaving the position illustrated in fig2 due to accelerations , for example if subjected to vibrations or impact , such as will normally occur during transportation or handling . however , the connection is releasable . the connection is established by a frictional contact between the needle holder 2 , namely its retaining portion , and the locking member 10 . the seating surfaces co - operating in this frictional contact taper in a conical arrangement in the distal direction . when the frictional contact connection is released , the locking member 10 slides in the distal direction relative to the injection needle 1 . the injection needle 1 extends through the locking member 10 , which has a central bore for this purpose . the locking member 10 , generally or as a whole , has the shape of a slim bolt . it imparts stiffness to the needle guard 6 and to its locating elements 8 with respect to the radial direction . one function of the lock mechanism 3 is to establish a locking connection with the needle guard 6 to prevent it from moving in the proximal direction when it is disposed in a distal guard position . in the guard position , the needle guard 6 assumes the same position by reference to the axis l as it does in the initial position illustrated in fig3 . however , when the needle guard 6 is in the guard position , it is prevented from moving in the proximal direction by the lock mechanism 3 . to enable it to fulfil the locking function , the lock mechanism 3 has two locking elements 5 . the locking elements 5 are respectively provided in the form of a flexibly elastic lug . the locking elements 5 are disposed in the sleeve casing of the lock mechanism 3 , each extending out in the distal direction from a proximal base or root region . the locking elements 5 each have a free distal end . the distal end faces of the locking elements 5 acts as stop surfaces for the proximal end faces of the locating elements 8 lying axially opposite when the needle guard 6 is in the guard position . the locking elements 5 therefore respectively act as a lock stop and the locating elements 8 respectively act as a complementary lock stop to lock the needle guard 6 in the guard position . in the guard position , the needle guard surrounds the injection portion of the injection needle 1 to beyond its needle tip . in the initial state illustrated in fig3 , the lock stop of the locking element 5 and the lock complementary stop of the locating element 8 are not engaged . the locating element 8 extends in the proximal direction , terminating just short of the guide 12 or sits at least free of tension on the distal end of the guide 12 . from this position , it can be moved radially inward past the locking element 5 unhindered as the needle guard 6 is moved in . the same applies to the pair comprising the locking element 5 and locating element 8 offset by 180 ° in the circumferential direction . although , in some preferred embodiments , the needle guard device has several pairs of co - operating elements 5 and 8 and these are advantageously disposed in a symmetrical arrangement about the axis l , a single pair of elements 5 , 8 is enough to establish the lock . a description will be given below with reference to fig4 to 7 to explain the sequence which takes place during an injection . once the user has attached the needle guard device to the injection device as described above , the injection needle 1 is primed . the user then selects the dose to be injected . having selected the dose , he places the injection device on the desired injection point of the skin via the distal end face of the needle guard 6 and pushes the injection device against the skin . due to this pressing action in the distal direction , the needle guard 6 moves axially against the elastic force of the return element 9 through the annular gap between the lock mechanism 3 and the locking member 10 . the needle guard 6 is axially guided relative to the lock mechanism 3 but is not able to rotate . in what is the first distal portion of the movement , the locating elements 8 slide along the guide 12 . the guide 12 and locking elements are shaped and spaced radially apart from one another so that the locating elements 8 are able to move radially inward past the respective co - operating lock element 5 without any difficulty . the lock mechanism 3 becomes inwardly wider in the circumferential region of its locking elements 5 in the proximal direction to the degree that the locating elements 8 are able to bend outward virtually unhindered between the guide and the locking elements 5 , and in the ideal situation without the locking elements 5 deforming . at the proximal ends of the guide 12 , the locating elements 8 move across the edges distally bounding the complementary locating elements 11 at this point and inward due to their natural rebounding elastic force ; they therefore snap into the complementary locating elements 11 . the locating elements 8 and complementary locating elements 11 are now hooked to one another in pairs in a driving connection . as explained above , the internal face of the locking elements 5 facing the guide 12 is shaped so that a sufficiently large distance is left free between the internal face and the guide 12 across the entire stroke of the needle guard 6 so that the locating element 8 does not exert any pressure on the locking element 5 or at least any outwardly directed pressure on the locking element 5 . the complementary locating element 11 and the guide 12 are also shaped so that in the initial position , the locating element 8 is bent outward from its distal initial position in the driving connection and is therefore at a greater distance from the central longitudinal axis l in the driving connection than in the distal initial position . in the driving connection , an external face of the locating element 8 facing the locking element 5 is at a greater distance from the central longitudinal axis l than the locking element 5 on its internal face in the distal region . fig4 illustrates the needle guard device in an initial state prior to use , in which the needle guard 6 assumes the distal initial position . in the initial position , the needle guard 6 is held on the lock mechanism 3 by the co - operating stops 4 and 7 ( fig3 ). the two locating elements 8 lie distally immediately in front of the guide 12 and are relaxed . when an axial pressure is applied to the needle guard 6 in the proximal direction , the needle guard 6 moves in the proximal direction relative to the lock mechanism 3 and to the locking member 10 disposed in its proximal initial position . coinciding with the start of the movement , after an initial or triggering stroke y , the locating elements 8 move into a guiding contact with the guide 12 and bend radially outward , conforming to the inclination of the guide 12 . the locating elements 8 move along the guide 12 in the gap between the locking member 10 and lock elements 5 , and are bent radially outward to a constantly more pronounced degree until reaching the proximal end of the guide 12 , and the locating elements 8 snap radially inward behind the complementary locating element 11 due to their elastic rebounding force , thereby establishing the driving connection . from the intermediate or triggering position y , the needle guard is no longer able to move back into the unlocked initial position when relieved of the external pressing force and is thus left to its own devices . fig5 illustrates the needle guard device with the needle guard 6 in the triggering position y . due to the position of the complementary locating element 11 , pushed far forward in the distal direction , the driving connection was already established before the tip of the injection needle 1 was projecting in the distal direction beyond the needle guard 6 . in the embodiment illustrated as an example , the needle tip is or rests back from the needle guard 6 by a short distance . further pressure applied to the needle guard 6 causes the needle guard 6 to move farther into the lock mechanism 3 against the force of the spring element 9 . during this additional retracting movement , the locating elements 8 move across the axially straight , cylindrical , circumferential surface adjoining the complementary locating element 11 in the proximal direction . fig6 illustrates the needle guard device after effecting the releasing stroke x with the needle guard 6 in the releasing position . the needle guard 6 has moved into the axial overlap with the lock mechanism 3 by its whole length . in this fully retracted state , the distal end faces of the lock mechanism 3 , needle guard 6 and locking member 10 are on the same axial level . the injection needle 1 extends beyond the common end face by its full injection portion , i . e . the injection needle 1 has penetrated the skin and the subcutaneous tissue lying underneath as far as the desired penetration depth as measured along the injection needle 1 , and the set dose can be administered . during administering , only the pressure needed to overcome the rebounding elastic force of the spring element 9 need be applied . once the set dose has been administered , the user moves the injection device axially away from the injection point in the proximal direction so that the needle guard 6 is relieved of external pressure . when the needle guard 6 is relieved of the external force , the needle guard 6 automatically moves forward in the distal direction again due to the rebounding force of the spring element 9 until the locating elements 8 move into an abutting contact with the complementary locating element 11 . the distance at which the complementary locating element 11 is from the contact surface of the needle holder 2 in the initial position ( fig4 ) is dimensioned so that the locking member 10 , now in the re - established driving connection produced by the locating elements 8 and the complementary locating element 11 , is driven in the distal direction by the needle guard 6 . the same happens when the needle guard 6 is relieved of the external force in the triggering position y . during the course of the joint movement of the needle guard 6 and locking member 10 , the locating elements 8 move in the distal direction in front of the locking elements 5 of the lock mechanism 3 . the locating elements 8 , i . e . the ends thereof which have located , are radially farther out than is the case when the needle guard 6 is in the initial position . during the outward movement , the locking elements 5 are therefore bent radially outward and snap back radially inward as soon as the locating elements 8 have passed them due to their natural elastic rebounding force . fig7 illustrates the needle guard device after the injection , with the needle guard 6 in the distal - most position . at the end of the movement of the needle guard 6 in the distal direction , the needle guard device automatically locks via or through the co - operating locating elements 8 and locking elements 5 so that the distal - most position is now the locked guard position of the needle guard 6 . the locking member 10 supports the locating elements 8 radially inwardly so that they can not be moved out of the lock connection with the locking elements 5 . the locking elements 5 , locating elements 8 and guide 12 are advantageously shaped so that the locking elements 5 are elastically biased in the distal direction to a relevant degree only during the movement of the needle guard 6 . the locating elements 8 which bend outward during the retracting movement should at most cause the locking elements 5 to bend to a significantly lesser degree . in some preferred embodiments , the locking elements 5 are not biased at all during the retracting movement . in the embodiment illustrated as an example , this is achieved due to the inclined contour of the internal faces of the locking elements 5 and guide 12 as viewed in longitudinal section and the slim locating elements 8 . the complementary locating elements 11 are disposed with respect to the axial direction so that they are axially overlapped by the lock mechanism 3 when the needle guard 6 ( which also may be thought of and / or referred to as a cover ) is in the guard position , so that the lock mechanism 3 prevents manipulations of the locating elements 8 which could cause the locating elements 8 to move out of the driving connection . after the injection , the user removes the needle guard device from the injection device and disposes of it . for a new injection , a new needle guard device in the initial state illustrated in fig3 and 4 is attached to the injection device . fig8 illustrates a needle guard device based on a second embodiment in accordance with the present invention , with its components aligned along a central longitudinal axis l one after the other in the order in which they are assembled . the needle guard device comprises an injection needle 1 , which is held by a needle holder 2 , as was the case in the first embodiment , a lock mechanism 3 which also has a fixing and guide mechanism for attaching the needle guard device to the distal end of an injection device and forms a non - rotatable , axial guide of the needle guard 6 , a spring element 9 a and a locking member 10 . the needle guard device also has a distal needle guard 6 . the needle holder 2 is inserted in the sleeve - shaped lock mechanism 3 and secured so that it is not able to move . a needle injection portion 1 a projects beyond the lock mechanism 3 in the distal direction by a length suitable for administering a subcutaneous injection . in the proximal region , the lock mechanism 3 surrounds a needle connecting portion 1 b and projects beyond it in the proximal direction . the needle guard 6 is retained in the initial position relative to the lock mechanism 3 against the force of the spring element 9 a by means of the locking member 10 . fig9 shows the lock mechanism 3 in two longitudinal sections , offset from one another by 90 °, and a perspective view . the lock mechanism 3 has two pocket - shaped recesses 3 a in the internal face at the distal end extending circumferentially about the longitudinal axis l . the recesses 3 a merge into the internal surface via a steep shoulder at their proximal end in each case . the two shoulders each form a translation stop 3 b pointing in the distal direction . disposed to the side of the recesses 3 a are respective axially extending guides 3 e to ensure that the needle guard 6 is guided in a straight line . two other pocket - shaped recesses 3 c are provided at the distal end of the lock mechanism 3 in the same internal face , which are offset from the recesses 3 a on the circumference of the internal face by 90 ° in each case . the recesses 3 c each merge into the casing internal face via a steep shoulder at their distal end . the two shoulders each form a translation stop 3 d pointing in the proximal direction . also still in the distal end portion , the lock mechanism 3 acts as a translation stop 3 f for the locking member 10 . the translation stops 3 b and 3 d define the guard position of the needle guard 6 . the translation stop 3 d establishes a lock to prevent extraction again and the translation stop 3 b establishes a lock to prevent retraction and thus replaces the lock stop of the locking element 5 in the first embodiment . fig1 shows the needle guard 6 . the needle guard 6 has axial guides 6 e , which co - operate with the guides 3 e of the lock mechanism 3 and with them guide the needle guard 6 linearly but prevent it from rotating . disposed at its proximal end , the needle guard 6 has two locking elements 6 b offset from one another in the circumferential direction by 180 °, which are provided in the form of resilient lugs in this exemplary embodiment . the locking elements 6 b are outwardly inclined in the proximal direction . finally , two locating elements 6 d in the form of outwardly projecting cams are provided on the external circumference of the needle guard 6 , likewise at its proximal end offset from one another by 180 ° in the circumferential direction . on a face pointing in the circumferential direction about the longitudinal axis l , the locating elements 6 d respectively have an inclination with respect to the longitudinal axis l so that the respective locating element 6 d forms a ramp on the relevant side . fig1 and 12 illustrate the needle holder 2 of the second embodiment . the needle holder 2 has a base 2 a and a central retaining region for the injection needle 1 extending out from the base 2 a . the base 2 a is provided with two passages 2 b , through which the needle guard 21 is able to retract in the proximal direction into a proximal guard position and which also serve as a means of locking the needle guard 21 in its guard position . projecting out from the base 2 a in the distal direction outside of and adjacent to the retaining region are two projections offset from one another in the circumferential direction about the longitudinal axis by 180 °, each of which is inclined in a ramp shape on a distal side to form a respective inclined guide 2 c for the locking member 10 . facing the ramp - shaped , inclined guides 2 c , another respective projection 2 d extends out from the base 2 a in the distal direction . the plane of the section illustrated in fig1 extends through the longitudinal axis l and the gaps between one of the respective projections forming the guides 2 c and the projection 2 d facing the respective guide 2 c . fig1 is a perspective view of the locking member 10 . fig1 is a plan view of the bottom face of the locking member 10 , i . e . a view in the distal direction . the locking member 10 is hollow cylindrical . molded into the casing of the locking member 10 are two cut - outs 13 offset from one another in the circumferential direction by 180 ° which extend through the casing and respectively form a track 14 inclined in the circumferential direction on one side . a projection 15 extends out in the proximal direction from a distal peripheral strip of the locking member 10 into the respective cut - out 13 . the two cut - outs 13 are circumferentially framed by the casing of the locking member 10 and an axially extending passage 16 is respectively formed distally in front of the tracks 14 in the internal face of the casing next to the projections 15 , which extends continuously from the distal end of the locking member 10 to the respective cut - out 13 . when the needle guard device is assembled , the locking member 10 with its two passages 16 moves across the locating elements 6 d of the needle guard 6 so that the locating elements 6 d move into the respective co - operating cut - out 13 . the locating elements 6 d are then moved behind the respective projection 15 into the circumferential region 17 by rotating the locking member 10 , still during the assembly process , so that the locating elements 6 d locate behind the distal edge of the locking member 10 in its circumferential regions 17 . the two circumferential regions 17 respectively form a translation stop and in this sense a complementary locating element 17 for the respective co - operating locating element 6 d . the needle guard 6 is retained on the lock mechanism 3 in this abutting contact against the force of the spring elements 9 and 9 a . the projections 15 are disposed in the direction extending transversely to the longitudinal direction of the injection needle 1 between the passage 16 and the complementary locating element 17 . in a guide contact with the locating elements 6 d , they separate the passage 16 from the respective co - operating complementary locating element 17 so that the locating elements 6 d either overlap the complementary locating elements 17 when the locking member 10 is in a first position or overlap the passages 16 when the locking member 10 is in a second position . the projections 17 fulfil the function of separating elements . the locking member 10 is able to move axially backwards and forwards relative to the needle holder 2 and lock mechanism 3 and also rotate about the longitudinal axis l . on its bottom face , the locking member 10 has an annular base 18 extending radially inwardly at the proximal end of its casing and locating elements 19 projecting out from the base 18 in the proximal direction , in total two locating elements 19 , which are offset from one another in the circumferential direction by 180 °. two passages 20 are provided in the base 18 for the proximal guard 21 , offset from one another by 180 ° in the circumferential direction . fig1 illustrates the proximal needle guard 21 . the needle guard 21 has an annular base at a distal end and flexible legs or fingers 21 a extending elastically out from the base in the proximal direction toward the direction of the longitudinal axis l . a projection 21 b is provided on the external face of the fingers 21 a in each case . the projections 21 b taper in an arrow shape in the proximal direction and each forms a stop for the needle guard 21 pointing in the distal direction . fig1 illustrates the components which co - operate to lock the needle guard 21 , the needle guard 21 having assumed a distal initial position which simultaneously also corresponds to a releasing position of the needle guard 21 . in the initial position , the needle guard 21 sits completely behind the connecting portion 1 b of the injection needle 1 in the distal direction . it also sits back behind the base 2 a of the needle holder 2 , i . e . the spring element 9 a pushes the needle guard 21 in the proximal direction against the base 2 a in its initial position . the fingers 21 a extend through the passages 20 of the locking member 10 ( fig1 ). when the needle guard device is in the initial state , the passages 20 and the passages 2 b of the needle holder 2 are offset from one another in the circumferential direction . the locating elements 19 of the locking member 10 are disposed axially facing the guides 2 b of the needle holder 2 . the spring element 9 a holds the locking member 10 via the needle guard 6 in the distal initial position illustrated in fig1 in which the needle guard 6 locates behind the locking member 10 in the circumferential regions 17 by means of its locating elements 6 d , pulling it into the distal initial position . this initial position is also illustrated in fig1 . the needle holder 2 and the locking member 10 also act as a sequence controller for locking the needle guard 6 to lock it in the guard position when it has moved out of its initial position into at least the triggering position and is then relieved of the external force causing the movement in the proximal direction . fig1 illustrated the needle guard device and the needle guard 21 disposed in its proximal guard position . fig2 illustrates the needle guard device as a whole , likewise in this end state . a description will be given below explaining how the needle guard device based on the second exemplary embodiment operates with reference to fig1 to 22 but also with reference to fig8 to 17 , including fig1 and 17 . the needle guard device is connected to the injection device in the initial state illustrated in fig1 , 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 21 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 needle guard 6 moves in the proximal direction relative to the needle holder 2 so that , conversely , the needle injection portion 1 a projects forward . fig2 illustrates the needle guard device in the piercing state whilst the medicament is being administered . due to the external force acting on the needle guard 6 in the proximal direction , the needle guard 6 moves in the proximal direction against the rebounding spring force of the spring element 9 a relative to the needle holder 2 and also relative to the locking member 10 . another spring element 9 surrounding the needle guard 21 is supported on the needle holder 2 in the proximal direction and on the needle guard 6 in the distal direction , namely on its proximal end in the embodiment illustrated as an example . the retracting needle guard 6 therefore pushes on the locking member 10 in the proximal direction via the spring element 9 . since the locating elements 6 d are still in a guide contact with the respective co - operating projection 15 at the start of the movement and the needle guard 6 is guided in a straight line and prevented from rotating , the locking member 10 is still not able to rotate . at the end of the triggering stroke , having reached the triggering position y , the locating elements 6 d of the needle guard 6 are moved out of the axial overlap with the projections 15 of the locking member 10 . the axial length of the projections 15 simultaneously also defines the length of the triggering stroke y , i . e . the triggering position y by reference to the initial position . as soon as the locating elements 6 d have passed the proximal end of the respective co - operating projection 15 and the guide contact of the locating elements 6 d and the projections 15 has therefore been released , the locating elements 19 are able to slide on the guides 2 c . since the guide contact between the locating elements 19 and the guides 2 c has then been established , the locking member 10 rotates relative to the needle holder 2 , the lock mechanism 3 and also relative to the needle guard 6 in accordance with the direction of inclination of the guides 2 c about the longitudinal axis l , out of the first position illustrated in fig1 into the second position illustrated in fig1 , in which the locating elements 6 d are in axial alignment with the passages 16 . fig1 and 20 illustrate the locking member 10 at the start and at the end of its rotating movement . under the effect of the external force , the needle guard 6 moves continuously further against the force of the spring element 9 and also the spring element 9 a in the direction toward the releasing position . as this happens , the position of angular rotation of the locking member 10 does not change . a translating movement is superimposed on the rotating movement , causing the locating elements 19 of the locking member 10 to slide on the respective co - operating guide 2 c . the translating and rotating movement is restricted by the abutting contact of the locating elements 19 and the projections 2 d . the projections 2 d act as stops for the rotating movement . the locking member 10 drives the needle guard 21 with it during the rotating movement because the fingers 21 a are extending through the passages 20 . as soon as the locking member 10 has reached its neutral position illustrated in fig1 , the passages 20 of the locking member 10 ( fig1 ) overlap the passages 2 b of the needle holder 2 ( fig1 and 12 ) so that the fingers 21 a of the needle guard 21 are able to pass through the passages 2 b due to the force of the spring element 9 a . the fingers 21 a are pushed by the spring element 9 a as far as 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 entered the passages 2 b of the needle holder 2 , the fingers 21 a prevent the locking member 10 from being turned back into its initial position ( fig1 ). when the injection needle 1 has been removed from the tissue and the needle guard 6 has been relieved of pressure as a result , the spring elements 9 and 9 a move the needle guard 6 in the distal direction . the position of the two projections 15 in the circumferential direction is selected so that the locating elements 6 d move into the passages 16 as the needle guard 6 moves in the distal direction , as a result of which the needle guard 6 is finally released by the locking member 10 and the locking elements 6 b are able to move into the recesses 3 a of the lock mechanism 3 ( fig9 and 10 ) and lock the needle guard 6 in its distal guard position due to the lock connection with the lock stops 3 b and prevent a movement in the proximal direction . co - operating with the stops 3 d , the locating elements 6 d prevent the needle guard 6 from moving completely out of the lock mechanism 3 in the distal direction . the needle guard device is detached from the injection device with the needle guard 6 locked in its guard position . under the action of the spring element 9 a , the proximal needle guard 21 moves in the proximal direction relative to the needle holder 2 into its guard position illustrated in fig2 . in the guard position , the fingers 21 a project in the proximal direction beyond the tip of the needle connecting portion 1 b . the needle guard 21 is locked by a lock connection between its projections 21 b and the base 2 a of the needle holder 2 , preventing a movement back in the distal direction . the needle guard 21 is supported on the needle holder 2 in the distal direction by its annular base . fig2 illustrates another exemplary embodiment of a needle guard in accordance with the present invention . this embodiment is a modification of the second embodiment described above . the proximal needle guard 21 has been dispensed with . accordingly , the spring element 9 a is also dispensed with . as regards the needle holder 2 and the locking member 10 , the passages for the fingers 21 a of the needle guard 21 are dispensed with . otherwise , the third embodiment is the same as the second embodiment and its control sequence proceeds in a similar manner . fig2 and 25 illustrate the needle guard device based on the third embodiment in two longitudinal sections offset from one another by 90 °. in fig2 and 25 , the needle guard 6 has assumed its unlocked initial position . the spring element 9 is longer than the spring element 9 of the second embodiment in that it is supported on the base of the locking member 10 in the proximal direction , as is the case with the second embodiment , but in the distal direction is supported on the needle guard 6 close to its distal end . for details of the motion sequence which takes place during an injection , e . g ., the components co - operating to produce early triggering of the needle guard 6 , reference may be made to the explanation given above in connection with the second embodiment . 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 .
a needle protection device for use with an injection device , the needle protection device including a moveable needle protection element which moves through a release course of movement into a locking engagement position as a result of an elastic force , the locking engagement position being achieved when the needle protection element moves from a starting position to a triggering position , when the needle protection element moves over a small portion of the release course , and being maintained when the needle protection element is no longer subjected to an external force in the triggering position .