The invention relates to an endoscope having a shaft in which at least one working channel is positioned and having on the distal end of the shaft an endoscope head, such that the part of the working channel contained in the endoscope head can be rotated with respect to the related working channel by a Bowden cable that is mounted on a control handle on the proximal end by a collet. To configure an endoscope in such a manner that it ensures simple construction as well as a constantly even tension of the Bowden cable, it is proposed with the invention that the depth of insertion of a cable cord of the Bowden cable into the collet can be limited by a pressure element acting on the cable cord and collet.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority of German patent application No. 10 2005 041 454.0 filed on Aug. 31, 2005, the content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to an endoscope having a shaft in which at least one working channel is positioned and having on the distal end of the shaft an endoscope head, such that the part of the working channel contained in the endoscope head can be rotated with respect to the related working channel by a Bowden cable that is mounted on a control handle on the proximal end by a collet.

BACKGROUND OF THE INVENTION

In order to allow a medical instrument brought into the surgical area by way of the working channel to be directed accurately to the area of application, a known method is to configure the part of the working channel situated in the endoscope head so that it can be rotated with respect to the related working channel by means of a Bowden cable. In the endoscope introduced in EP 1 112 019 B1, the Bowden cable serving to rotate the working channel is mounted on the proximal end by means of a collet mounted on a control handle. By means of the collet, the cable cord of the Bowden cable is grasped by clamping and is held clamped in the collet according to the depth of insertion.

This known construction for clamping the Bowden cable has the disadvantage that the cable cord can be inserted so deep in the collet that the cable cord becomes too taut and it becomes scarcely possible to rotate the working channel. To minimize this danger, the working channel and thus the cable cord of the Bowden cable must first be moved into a predetermined starting position so that thereafter a sufficient but not too taut tightening of the cable cord by the collet is possible. This known clamping method is, on the one hand, complicated and, on the other hand, does not prevent faulty tightening of the cable cord.

On this basis, it is the object of the invention to produce an endoscope of the aforementioned type in such a way that a constantly even tension of the Bowden cable is ensured, along with simple construction.

SUMMARY OF THE INVENTION

The fulfillment of this object according to the invention is characterized in that the depth of insertion of a cable cord of the Bowden cable into the collet can be limited by a pressure element applied to the cable cord and collet.

Because the invention limits the depth of insertion of the cable cord of the Bowden into the collet, it becomes possible for the first time to maintain constant uniform depth of insertion and thus also a uniform tension of the cable cord. The risk of faulty tightening of the cable cord in assembling the Bowden cable is avoided thanks to this structural design.

According to a practical embodiment of the invention it is proposed that a cone is configured on the proximal end of the collet so that it engages with a counter-cone that is configured in a nut that can be screwed onto the collet. The engagement of cone and counter-cone ensures a secure and straight mounting of the collet in the nut, so that in the cone of the collet at least one clamping slit is configured running in the longitudinal direction of the collet whereby the cable cord is fixed in the collet by clamping when the collet cone runs up against the counter-cone.

To ensure that the counter-cone is always form-fitting contiguous to the cone of the collet, the pressure element according to the invention acts on the counter-cone by means of at least one spring element.

In addition, according to a preferred embodiment of the invention it is proposed that the pressure element is configured as a cap-shaped component, so that the axial length of the pressure element corresponds to the preferred and maximal insertion depth of the cable cord into the collet. Because the cap-shaped pressure element is spring-loaded and contiguous with the counter-cone, which defines the final position of the collet in the nut, there results an always uniform and predetermined tightening of the cable cord, because upon screwing the nut onto the collet positioned coaxially on the cable cord, the cable cord on the proximal end, corresponding only to the axial length of the pressure element, can extend above the collet. Thus, in installing the Bowden cable on the control handle, the insertion depth of the cable cord is restricted by the pressure element.

It is further proposed with the invention that the spring element is supported on the distal end on a surrounding collar of the cap-shaped pressure element and on the proximal end on a rear wall of the nut that is configured as a cap nut.

To ensure that the cable cord of the Bowden cable is always perfectly centered in the pressure element, it is proposed with the invention that a closed rear wall of the cap-shaped pressure element is configured tapering toward the outside.

It is finally proposed with the invention that the counter-cone is configured on a sleeve that can be inserted into the nut, so that the sleeve can be fixed secure against rotation in the nut, for instance by cementing, in order to prevent turning the sleeve that is equipped with the counter-cone while screwing on the nut.

To allow simple, level screwing of the nut onto the collet, on the distal end of the sleeve a non-threaded recess is configured. This recess, which extends the inner diameter of the sleeve, allows the collect to be centered in the nut.

Additional characteristics and advantages of the invention can be seen by referring to the appended sketches, in which an embodiment of the endoscope according to the invention is depicted in exemplary manner.

DETAILED DESCRIPTION OF THE INVENTION

InFIG. 1is seen the distal end of an endoscope1having an endoscope head3that constitutes the distal end of an endoscope shaft2and forms an extension of the endoscope shaft2.

Inside the shaft2, as can be seen inFIG. 7, several channels are configured, running in the longitudinal direction, in particular a working channel4, an irrigation channel5a, an air channel5b, and two illumination channels6. In addition, the lens system7of the endoscope1extends in the longitudinal direction of the entire shaft2.

To ensure that the operator working with the endoscope always has a clear view of the surgical area, the rinse water exiting from the irrigation channel5ais diverted by a duct8made of baffle plate onto the lens system7and the light systems positioned in the illumination channels6, so that in the illustrated embodiment the rinse liquid is conducted to the lens system7and to the illumination channels6by correspondingly positioned conducting channels9, as seen in particular inFIG. 7. After completion of the lens system rinsing, the irrigation liquid drops are blown away by the air stream emerging from the air channel5b.

In addition to this drying of the lens system7, the air stream conducted by the air channel5bserves to inflate the organs to make it possible thus to insert the endoscope1into the examination area with as little friction as possible.

The endoscope head3is connected with the endoscope shaft2of the endoscope1in the illustrated embodiment by a sleeve11that can be screwed onto an outer thread10of the endoscope head2and that at the same time constitutes the outer housing of the endoscope head3.

Finally,FIG. 2shows a side view corresponding toFIG. 1, but with the sleeve1removed so that the inner structure of the endoscope head3is now recognizable. As can be seen from this image as well as fromFIG. 3, the endoscope head3is constructed as a housing divided in two in the axial direction of the shaft1in such a way that the working channel4is positioned in the one housing section and the lens system7, the illumination channels6for the lighting systems, and the irrigation channels5are positioned in the other housing section.

The extension of the working channel4in the endoscope head3has the peculiarity that this part4ais configured in the shaft1so that it can rotate with respect to the related working channel4in the plane of the impact plate12. Because of this ability of the distal part4aof the working channel4to rotate, it is possible to direct a medical instrument, which has been inserted from the proximal end of the endoscope1into the working channel4, accurately to the surgical area. The distal part4aof the working channel4rotates around a pivot axis13by means of a Bowden cable14that is mounted in the shaft1and can be actuated by a control handle15on the proximal end of the endoscope1, as is shown inFIG. 4.

As can further be seen fromFIGS. 2 and 3, the rotatable part4aof the working channel4is pre-tensioned by a spring element16in a starting position in order to have a defined starting position of the working channel4from which the movable part4acan rotate. Because of this starting position it is possible to define a zero point, so that the optical axis constitutes a thoroughly appropriate starting position/zero point position. In order to maintain this starting position also during motion, it is advantageous to provide a stopping device by which the rotatable part4aof the working channel4can be fixed in this starting position.

The Bowden cable is assembled and disassembled on the rotatable part4aof the working channel4and on the control handle15as follows:

At the beginning of the installation, a cable cord17of the Bowden cable14is inserted into a Bowden cable casing18and then the Bowden cable casing18including the cable cord17is introduced from the distal end of the endoscope head3into a Bowden cable channel19configured in the shaft1.

Then the endoscope head3is secured by the screw-in sleeve11on the endoscope shaft2. The cable cord7is pushed into the Bowden cable casing18until the cable cord17on the proximal end emerges again from the Bowden cable channel19in the area of the control handle15. The cable cord17is secured on the proximal end on the control handle15by a collet20that can be mounted onto the cable cord17and is clamped shut by screwing on a nut21with the cable cord17. The rotatable part4aof the working channel4can now be displaced by the control handle15.

The structure of the nut21, configured as a cap nut, and of the collet20, as well as the manner of tightening the cable cord17can be seen from the enlarged detail view inFIG. 5.

As can be seen from the sectional view inFIG. 5, the proximal end of the collet20, onto which the nut21is mounted, is configured as a cone20a. For insertion of the collet20, the nut21has a pocket hole boring22, which is inserted essentially flush with the bore hole22shutting off a sleeve23, whose proximal end constitutes a counter-cone23ato the cone20aof the collet20. The depth of insertion of the collet20into the sleeve23and thus also into the nut21is thus limited by the fact that the cone20aof the collet20comes into essentially form-fitting contact on the counter-cone23aof the sleeve23. To prevent rotation of the sleeve23inside the nut21upon screwing the nut21onto the collet20, the sleeve23is fixed against rotation in the pocket hole22of the nut21, for instance by cementing.

The nut21is secured on the collet20by an outer thread20bthat is configured on the collet20and engages with an inner thread23bconfigured in the sleeve23. As can be seen fromFIG. 5, a non-threaded recess23cis configured in order to facilitate level screwing of the nut2onto the collet20.

To enable the cable cord7to be fixed in the collet20by screwing the nut21onto the collet20and by pressing the counter-cone23aof the sleeve23onto the cone20aof the collet20, at least one clamping slit24is configured in the collet running in the longitudinal direction of the collet20, as is shown inFIG. 4. This clamping slit24allows a reduction of the diameter of the collet20and thus a clamping of the cable cord17positioned in the collet20when a radially acting force component is exerted on the collet20.

Perfect actuation of the rotatable part4aof the working channel4by the Bowden cable14depends on the correct tightness of the cable cord17of the Bowden cable14. For this purpose it is necessary to ensure that the cable cord17is inserted neither too far nor too little into the collet20and thus into the nut as well. If the cable cord17is inserted too deeply into the collet20and thus also into the nut21, this causes too taut a tightening of the cable cord17, so that it is barely possible to displace the rotatable part4a. A similar situation occurs with too weak a tightening of the cable cord17because of too short an insertion of the cable cord17into the collet20.

For assembly and disassembly of the collet20on the cable cord17and/or in the nut21, the collet20can be moved forward and backward in the longitudinal direction by means of a control lever26positioned on the control handle15.

In the embodiment illustrated inFIG. 5, the depth of insertion of the cable cord17into the collet20is limited by a cap-shaped pressure element25, which is pre-tensioned by a spring element27so that it is contiguous with the sleeve23on the proximal end. The spring element27here is positioned in the pocket hole22of the nut21on the proximal end in such a way that the spring element27is supported on the distal end on a surrounding collar25aof the cap-shaped pressure element25and on the proximal end on a rear wall of the nut21, which is configured as a cap nut.

The advantage of this structure is that the cable cord17is always held tight in a firmly defined position. This is ensured by the fact that, upon insertion of the collet20into the nut21, the cable cord17presses against the pressure element25, which in turn constantly presses against the cable cord17by means of the spring element27. As can be seen fromFIG. 5, a closed rear wall25bof the cap-shaped pressure element25is configured as tapering toward the outside, so that the proximal end of the cable cord17inside the pressure element25is always positioned exactly centered in the pressure element25and the pressure always acts centrally on the cable cord17. The cable cord17is of such dimensions that it is long enough in the starting condition to press against the pressure element25. As a result of this configuration of the pressure element25, the possibility of user-caused errors is definitely minimized.

To ensure that the cable cord17can be tightened several times with sufficient stability, the cable cord17is soldered tightly at the distal end, which is positioned on the rotatable part4aof the working channel4.

The endoscope head3is disassembled in reverse sequence and begins with the loosening of the nut2to release the cable cord17. Then the sleeve11is unscrewed and the endoscope head3is withdrawn from the endoscope shaft2.

An endoscope of this configuration is characterized in that a correct tension of the cable cord17of the Bowden cable17is always ensured.