Patent ID: 12245744

DETAILED DESCRIPTION

FIG.1shows an endoscope1, in this case a video endoscope, with an elongated shaft2, in the distal end of which an optical system in the form of an objective lens3is disposed. The objective lens3may have a lateral viewing direction, i.e., a viewing direction of the objective lens3indicated by the arrow4deviates from a longitudinal axis5of the video endoscope1.

Furthermore, the endoscope1comprises a main body10at which a first handle element11and a second handle element12are disposed.

The first handle element11is configured as a rotary wheel at the distal end of the main body. By means of the first handle element11, the shaft2, the objective lens3, and the main body10can be rotated around the longitudinal axis5of the endoscope, so that the viewing direction of the video endoscope also rotates around the longitudinal axis5of the video endoscope. This is indicated by the double arrow15.

An electronic image converter (not shown) is disposed in the shaft2proximally of the objective lens3, for example a CCD chip or a CMOS chip. Of course, several image converters may also be provided to image different color channels or partial images of stereo optics. The electronic image converter converts the image projected by the objective lens3into electrical signals, which are transmitted through the shaft2into the main body10and from there via a cable16to an external processing device (not shown). The processing device may process the electrical signals, for example, for display on a monitor or for storage in a memory element.

In order to keep the horizontal position of the video image constant when the viewing direction of the endoscope1is rotated, the image converter is rotatably arranged in the shaft2, and is rotationally coupled to the second handle element12. For this purpose, a magnetic coupling acting through the shaft or through the wall of the main body10is provided. The structure of this magnetic coupling is known per se and need not be explained in detail here.

The second handle element12is rotatably arranged relative to the first rotary body11and the main body10. If the viewing direction of the endoscope is now rotated by rotating the first handle element11, the second handle element12can be held in place at the same time, whereby the orientation of the electronic image converter also remains constant.

If the endoscope1has a straight viewing direction, i.e., the viewing direction is parallel to the longitudinal axis5, the two handle elements11and12may be omitted, since the endoscope1can then simply be held on the main body10and a rotational movement is not required.

FIGS.2and3show a prism holder20which is part of an optical system of the endoscope1. Here,FIG.2shows a section along the line B-B inFIG.3, andFIG.3shows a section along the line A-A ofFIG.2.

The prism holder20comprises a substantially cylindrical sleeve21in which a prism22is received. In the present example, the prism serves to deflect a beam of rays entering an entrance surface23by 90° at a reflection surface24and to guide it to an exit surface25.

An electronic image converter26is disposed at the exit surface25of the prism22. An optical filter element27may be provided between the exit surface25and the image converter26, which may comprise, for example, an IR cutoff filter or a Moiré filter. The image converter26is supplied via an electrical connection element28, via which video signals generated by the image converter26are also discharged. The connection element28may comprise a flexible circuit board.

For a clean optical image, the prism22must be aligned translationally and rotationally in the main x, y, z directions. Here, if necessary, a translational alignment in one main direction, e.g., the main direction z, can be omitted if this main direction is parallel to an optical axis of the optical system3, and the optical system is adjusted separately in this main direction.

For alignment of the prism22, the prism holder20has a first stop formed by a plane stop surface30. The stop surface30has a recess31in which the image converter26is arranged.

The prism22rests with the exit surface25, which is a planar surface, against the stop surface30, thereby fixing the prism with respect to a translation along the main direction x and with respect to a rotation about the main directions y and z.

A pressing element in the form of a pressing ball32presses on a surface33of the prism22opposite to the exit surface25and thus holds it in firm contact with the stop surface30. The pressing ball32is inserted into a channel34of the sleeve21and can be fixed there, for example by means of an adhesive. The adhesive is not shown for clarity. Instead of the pressing ball32, other pressing elements may also be used, for example a spring or a screw.

In order to fix the prism22with respect to a translation in the main direction y and a rotation about the main direction x, another stop surface could be provided which is perpendicular to the main direction x. However, such a stop surface would also cause an additional fixation with respect to a rotation about the main direction z, thus the position of the prism22would be overdetermined. Therefore, instead of another stop surface, a linear stop contour40is provided, which can be seen inFIG.3as a point of contact between a lateral planar surface41of the prism22and the second stop42. The linear stop contour40is only visible here as a point, since it runs perpendicular to the drawing plane ofFIG.3. The linear stop contour40is thus parallel to the stop surface30and perpendicular to the main direction x, although certain angular deviations, for example by up to +/−10°, or by up to +/−20°, can be tolerated.

The linear stop contour40fixes the prism22with respect to a translation in the main direction y and with respect to a rotation about the main direction x, without causing a further fixation with respect to a rotation about the main direction z. Thus, there is no overdetermination here.

A pressing element in the form of a pressing ball43presses on a surface44of the prism22opposite to the planar surface41and thus holds the prism22in firm contact with the linear stop contour40. The pressing ball43is inserted into a channel45of the sleeve21and can be fixed there, for example by means of an adhesive which is also not shown. Instead of the pressing ball43, other pressing elements can also be used, for example a spring or a screw.

The second stop42has a cylindrical outer contour in the region of the linear stop contour40, the linear stop contour40being a surface line of the cylindrical contour. This limits a surface pressure between the planar surface41and the second stop42.

The distance of the linear stop contour40from the stop surface30corresponds approximately to half the extension of the prism in the main direction x, thereby achieving a particularly stable contact of the prism22. At the same time, a line of action50of the pressure ball42on the prism22runs in such a way that it intersects the linear stop contour40or passes it at a distance which is smaller than 0.1 times the extension of the prism22in the direction of the line of action50. This reduces tilting moments and shear forces on the prism22as far as possible.

For easier placement of the pressure balls32,43, the sleeve21has flats46,47.

FIG.4shows another prism holder120of an endoscope in longitudinal section.

The prism holder120again comprises a substantially cylindrical sleeve121in which a prism122is received. In the present example, the prism serves to guide a beam of radiation entering an entrance surface123to an exit surface125without deflection.

An electronic image converter126is in turn disposed at the exit surface125of the prism122. The structure of the image converter126and the orientation of the prism122along the main directions x and y correspond to the solutions shown inFIGS.2and3for the prism holder20.

While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.