the design of an injector cap in accordance with the invention and attaching it to an ampoule support will now be illustrated first , with reference to fig1 . in the figures , the ampoule support is indicated by the reference numeral 5 . a cannula support 3 is placed at its front facing end , said cannula support in turn keeping the cannula 6 protruding towards the front both at its facing side and centrally . the cannula support 3 comprises a locking protrusion 9 , running in a circle , at the front end of its circular cylindrical section , said locking protrusion forming a heel at its end facing the ampoule support 5 , and tapering towards the other side . the components described above are those which are fixed in their positions . the cut - away sliding sleeve 1 is shown in fig1 and 2 , mounted slidably and like a cap . as with the components described herein below , this sleeve 1 is one of the movable components of the injector cap . in the initial state shown in fig1 and 2 , the injector is ready to administer an injection . to this end , the sliding sleeve 1 is situated in a first position in which its facing side exhibits its greatest distance from the ampoule support 5 . in this state , the cannula 6 is completely hidden within the sliding sleeve 1 . the sliding sleeve 1 is held in the position in which it is shown in fig1 and 2 by a spring 4 between the facing end of the cannula support 3 and inner attachment ( not shown ) at the facing end of the sliding sleeve 1 . a circular opening 7 is provided on the front facing wall of the sliding sleeve 1 , to provide the cannula 6 with a way of emerging . a locking ring , indicated at 11 , is mounted slidably in a guide on the inside of the sliding sleeve 1 . in the initial state shown in fig1 and 2 , the locking ring 11 comprises inner locking clips 8 , arranged circumferentially and forwards and converging inwards , as well as two spacer clips 2 likewise extending forwards and further outwards . the locking ring 11 abuts the stopper 12 of the sliding sleeve 1 via its spacer clips 2 , i . e ., via its front facing edge . the stopper 12 forms the front end of the guide for the locking ring 11 , said guide being worked out of the inside of the sliding sleeve 1 over a particular length . in this area , the sliding sleeve 1 also comprises two opposing stays 10 , exposed from the surrounding material , which at their free end form a heel protruding obliquely inwards . the stays 10 can be elastically deformed in the radial direction . proceeding from the state shown in fig1 and 2 , it can be shown by way of the representations in fig3 and 4 how the injector cap in accordance with the present invention functions . if a dose of medicine is to be administered by means of the injector , then said injector is placed on the skin of a patient at the front facing side of the sliding sleeve 1 . the ampoule support 5 is then slid forwards , such that the sliding sleeve 1 slides backwards relative to the ampoule support 5 and against the force of the spring 4 , until the cannula support 3 abuts the inner attachment at its front facing end , said attachment surrounding the opening 7 and being enclosed by the spring 4 . this state is shown in fig3 . activating the device as described above does not affect the position of the locking ring 11 comprising the clips 8 and clips 2 relative to the sliding sleeve 1 , i . e ., the spacer clips 2 are still pressing against the stopper 12 . what does change , however , is the position of the locking ring 11 relative to the cannula support 3 ; the cannula support 3 is slid , together with the ampoule support 5 , forwards into the locking ring 11 , through the locking clips 8 . as they pass through the locking protrusion 9 , this first pushes the locking clips 8 outwards , somewhat elastically , and they then latch in behind the locking protrusion 9 , fixing the locking ring 11 with respect to the cannula support 3 . in this state , the cannula 6 has traveled far out of the opening 7 , and the injection can be administered . after the injection has been administered , the spring 4 causes the sliding sleeve 1 to be slid back away from the cannula support 3 , as depicted in fig4 . since , as shown in fig3 and already mentioned above , the locking ring 11 is then fixed behind the locking protrusion 9 on the cannula support 3 by the locking clips 8 , it also remains fixed when the sliding sleeve 1 is brought forward again , i . e ., the sliding sleeve 1 moves forward again without slaving the locking ring 11 . as the sliding sleeve 1 thus moves forward , the stays 10 then slide along the outer circumference of the spacer clips 2 and are briefly , elastically pressed outwards as the rear heel passes over the spacer clips 2 , before they latch back inwards beyond the front end of the spacer clips 2 with their rear facing end . after this latching back , the stays 10 are in the position shown in fig4 i . e ., they abut the front area of the spacer clips 2 with their facing side . this locks or prevents the sliding sleeve 1 from sliding back again relative to the cannula support 3 or the ampoule support 5 . in the state depicted in fig4 once the medicine dose has been administered once , the sliding sleeve 1 is therefore blocked against sliding further and again completely covers the cannula 6 against the environment . in this way , using the injector again is positively prevented . the possibility of injury or infection from the needle is likewise prevented . the locking and / or blocking means of an injector cap in accordance with the invention are all substantially situated in the interior of the cap or have their functional parts facing the interior , such that repeated use — which in accordance with health care standards and regulations is not supposed to happen — can only be achieved by extensively manipulating it , which would probably lead to the injector or injector cap being destroyed . in the foregoing description embodiments of the invention have been presented for the purpose of illustration and description . it is not intended to be exhaustive or to limit the invention to the precise form disclosed . obvious modifications or variations are possible in light of the above teachings . the embodiment was chosen and described to provide the best illustration of the principals of the invention and its practical application , 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 .
an injector cap including a sleeve and a blocking means , wherein the sleeve is mounted slidably on a portion of an injection device , e . g ., on an ampoule support , is forced by a pre - tensioning means into a first position in which it covers a cannula carried by the injection device , and can be slid against the pre - tensioning means into a second position in which the cannula emerges from the end of the sleeve , and wherein the blocking means non - detachably blocks the sleeve against sliding when it has been returned from the second position to the first position .