as shown in fig1 , a shaft element according to a first embodiment of the invention comprises two segments a , b , namely a proximal segment a and a distal segment b , which can be displaced , that is , bent at an angle , with respect to the first segment a . between the two segments are situated three connecting elements 1 , 2 , 3 . said connecting elements 1 , 2 , 3 each comprise a joint c , c ′, c ″ at the point of connection to segment b . said joints are constructed in such a way as to permit tipping in all directions but do not permit a rotation around an axis parallel to the longitudinal axis 8 of the second segment b or around the longitudinal axis of the shaft that coincides with the longitudinal axis 8 of the second segment b in the elongated position shown in fig1 . a first connecting element 1 is fixed in the segment a . two additional connecting elements 2 , 3 are constructed as push rods 2 ′, 3 ′ or each is connected with a push rod 2 ′, 3 ′, so that the push rods 2 ′, 3 ′ are slidably mounted inside segment a and are fed through the first segment a in the proximal direction for actuation . the two connecting elements 2 , 3 each comprise an additional two - axis joint d , d ′. these joints too allow tipping in all directions , but permit no rotation around an axis parallel to the axis of the particular push rod . as shown in fig1 , the two push rods 2 ′, 3 ′ are fed through the peripheral area of segment a in order to allow as much space as possible for lines fed inside segment a , for example electrical supply and data lines or light conductors . according to the embodiment shown in fig1 , the first connecting element 1 is likewise positioned in the peripheral area of segments a , b . the supporting points of the connecting elements 1 , 2 , 3 on the second segment b or the joints c , c ′ c ″ form an approximately equilateral triangle whose surface stands perpendicular on the longitudinal axis 8 of the second segment b and defines a proximal end plane 4 of the second segment b . the first segment a comprises a lumen 5 for feeding the electrical lines , lighting lines and / or additional channels that are not seen in fig1 . the second segment b also comprises a hollow space of this type ( not illustrated ). according to fig2 , the bending of segment b with respect to segment a occurs by a linear sliding of one or both push rods 2 ′, 3 ′ in the direction of the arrows . by extending or shortening the connecting elements 2 , 3 or the part of the push rods 2 ′, 3 ′ found between the two segments , the joints c , c ′, c ″, d , d ′ are bent in defined manner and thereby a diagonal position of segment b is produced in relation to segment a . in the process , the connecting elements 2 , 3 can each be configured as a rigid rod 6 , 6 ′ in their distal portion positioned beyond the joint d , d ′. the direction and size of the angling of segment b are determined by the sliding of the push rods 2 ′, 3 ′. if the displacement of the push rods 2 ′, 3 ′ is measured , then conclusions can be drawn about the actual bending and thus about the viewing angle of a tip connected with segment b . this can be used , for example , for virtual reality applications . according to fig1 , the bending motion of the second segment always occurs around the joint c ″, that is , not symmetrically to the center longitudinal axis 8 ′ of the first segment . a symmetrical bending motion can be achieved through a modification according to fig4 a and 4 b . here the fixed connecting element 1 is configured as a doubly bent or angled sidearm 9 of the first segment a that attaches in the area between the push rods 2 ′, 3 ′ on the first segment a . the connecting point of the first connecting element 1 on the second segment b , that is , the joint c ″, on the other hand , is positioned centrally in the proximal end plane 4 of the second segment b . fig4 b shows an angled position of the embodiment from fig4 a . as can be seen in fig4 b , by sliding the push rods 2 ′, 3 ′ in the direction of the arrows , it is possible to control an angling of the second segment b in relation to the first segment a around a rotation point that lies on a center longitudinal axis 8 ′ of the first segment a . an additional embodiment of the invention is illustrated in fig5 a and 5 b . the joints c ″, c , c ′ of the connecting elements 1 , 2 , 3 in this embodiment form a triangle , which however is displaced in the proximal direction opposite a proximal end plane of the second shaft element b . for this purpose , the first connecting element 1 is configured as a partly rigid rod , such that a proximal portion 1 ′ is connected rigidly with the first shaft segment a and a distal portion 1 ″ is connected rigidly with the second shat segment b . the proximal portion 1 ′ is connected with the distal portion 1 ″ by the joint c ″. the second and third connecting elements 2 , 3 are only each configured as a rigid rod 6 , 6 ′ in their portion positioned distally from the other joint d , d ′, but they also comprise an additional distal portion that is configured as a rigid rod 6 ″, 6 ′″ and is connected with the rod 6 , 6 ′ by the joint c , c ′. the aforementioned distal portions of the second and third connecting elements 2 , 3 are each rigidly connected with the second shaft segment b . in particular , the second and third connecting elements can each be configured as a jointed rod with two two - axis joints . fig5 b shows an angled position of the embodiment from fig5 a . as is indicated symbolically in fig5 b by a shortening of the portions of the push rods 2 ′, 3 ′ extending proximally out of the proximal shaft element a , it is possible by sliding the push rods 2 ′, 3 ′ to angle the distal shaft segment b around a rotation point that is determined by the joint c ″ of the first connecting element 1 . as can further be seen in fig5 a and 5 b , the first connecting element can attach at a protrusion 18 that is connected internally with a mantle of the first shaft segment a . consequently , despite the restriction by the nearly centrally attaching first connecting element 1 , there remains a relatively large lumen 5 ′ for inserting additional functional elements of the endoscopic instrument . several of the described shaft elements can be positioned behind one another in an endoscopic instrument . in the process , for example , the proximal end surface of a first segment a can be configured to correspond with the proximal end surface 4 of the second segment b , on which connecting elements to an additional proximal segment attach ( not illustrated ). owing to the sequential arrangement of several segments of the described type , or of several shaft elements , an especially flexible structure of a shaft can be achieved . rather than by push rods 2 ′, 3 ′ passed through the proximal segment a , the connecting elements 2 , 3 can also be actuated by actuators that are positioned inside the proximal segment a . these actuators are controlled from the proximal end of the endoscopic instrument by operating elements and by control lines positioned inside the shaft . in this case as well , a precise positioning of the individual elements is possible . the elements employed in an inventive shaft element should be as produced so that they are as small and free from friction and wear as possible . excessively large joints would restrict structural space for other lines . various possibilities for producing the joints c , c ′, c ″, d , d ′ are illustrated by way of example in fig6 a through 6 c and fig7 a through 7 d . in each case here , the joints d , d ′ are illustrated as a connection between rigid rods 7 , 7 ′, which are portions of the connecting elements ; in similar manner , the joints c , c ′, c ″ can attach directly on the second shaft segment b or on a proximal end surface 4 of the second shaft segment b . according to fig6 a , a very simple structure for a joint can be realized in the form of a spiral spring 10 ; likewise , for example , disc springs can be used . the springs can be produced , for example , of polymer or metallic materials . another especially simple structure can result from a bellows 11 in whose end - surface apertures 12 , 12 ′ the ends of the rods 7 , 7 ′ can be firmly inserted ( fig6 b ). according to fig6 c , the joints can also be configured as miniature shaft couplings or cardan joints with two axes standing perpendicular to one another that can be realized by rods 13 , 13 ′ mounted rotatably . the joints can also be realized by solid - state joints . an additional possibility for configuring the joints is obtained from the use of elastomer materials . according to fig7 a , the ends of the rods 7 , 7 ′ are of flat configuration and are molded with an elastomer material . according to fig7 b , the plates 14 , 14 ′ can be equipped with boreholes in order to avoid rotation of the two parts with respect to one another . an even simpler structure can be achieved by a shrinkable or cementable elastomer , for example a hose 16 that , according to fig7 c , connects the two rods 7 , 7 ′ with one another . likewise the rods 7 , 7 ′ can be connected together by an elastic intermediate piece 17 ( fig7 d ). for the sake of clarity , all reference numbers are not indicated in all drawings . given reference numbers retain the same significance in the illustrations .
a shaft element for an endoscopic instrument includes a first , proximal shaft segment and a second , distal shaft segment , such that the second shaft segment is connected with the first shaft segment by three connecting elements , such that the connecting elements each include a first two - axis joint , such that the first joints form a triangle and such that the first connecting element is connected with the first shaft segment in such a way that it cannot slide with respect to the latter in a longitudinal direction , and a second and third connecting elements can each be slid with respect to the first shaft segment in a longitudinal direction independently of one another . the invention also relates to an endoscopic instrument , in particular an endoscope with such a shaft segment .