Rigid endoscope

Abstract

Rigid endoscope (1) with a fiber tube (2) whose distal end is closed by a window (3, 3'), and with a lens (6, 7) arranged in the fiber tube (2), which is held at a distance from the window (3) by a spacer device (10), wherein the spacer device is designed as a spacer tube (10) which is supported distally on the window (3) and proximally on the lens (6, 7), characterized in that the lens (6, 7) is arranged in a lens tube (5, 8) by means of which the lens (6, 7) is mounted in the fiber tube (2) and supported on the spacer tube (10), that the lens tube (5, 8) is designed in its distal end region (8) forming a step with a smaller diameter, and that the spacer tube (10) is supported at its distal end on the window (3, 3') and at its proximal end on the step on which the lens tube (5, 8) is supported in its transitions to a diameter-reduced distal end region (8).

Description

[0001] The invention relates to a rigid endoscope of the type mentioned in the preamble of claim 1.

[0002] Such an endoscope is known in substance from JP H03-81716 A, insofar as a "ring" mentioned therein can be considered a spacer tube. DE 10 2004 009 219 A1 also discloses a rigid endoscope in which a lens is supported by a fiber tube that also forms the mount for a window. This keeps the lens at a distance from the window by a spacer device, thus ensuring precise optical alignment of the lens. US 2002 / 0128535 A1 does not disclose a rigid endoscope, but it does show a spacer device that keeps a lens at a distance from a window.

[0003] US 2012 / 0 253 129 A1 discloses an endoscope with an imaging optic having one window and two light optics, in which the windows are formed by open holes, such that the front face of a distal lens forms a window. The imaging optic does not have a spacer tube. US 5 630 795 A discloses spacers between each pair of lenses, i.e., within an objective lens, not between a window and an objective lens. DE 44 35 644 A1 describes the arrangement of an objective lens using spacers in a through-channel, but not the use of tubular spacers. DE 197 42 454 A1 shows spacer tubes, but not supported distally at a window, rather at a stop in the front end region of an endoscope optic.

[0004] In the design known from DE 10 2004 009 219 A1, the lens rests against an inwardly projecting stop formed by a step on the fiber tube. This allows for precise maintenance of the distance between the lens and the window attached to the fiber tube. However, this design has disadvantages.

[0005] The inward-projecting protrusion reduces the diameter of the fiber tube. This leads to increased tolerances during window installation. The window must be held in place during fastening within the fiber tube, which is typically done by soldering. This is usually achieved using a mandrel inserted from the inside through the fiber tube to the window. This mandrel supports the window at several points or across its surface and holds it in place during soldering. The protrusion, which acts as a stop, reduces the inner diameter of the fiber tube at this point, necessitating a reduction in the diameter of the mandrel that can be inserted. This reduces the contact area of ​​the mandrel with the window and consequently the adjustment accuracy. This can lead to undesirable tilting of the window.

[0006] Another disadvantage of the stage forming the stop is the reduced cleanability in this area. For example, flux residue remaining in the corner could outgas in the later hermetically sealed fiber tube and cloud the optical surfaces of the lens due to condensation.

[0007] In the area between the window and the lens, another as yet unresolved problem exists, resulting from the window's mounting. The window is soldered to the inner surface of the fiber optic tube along its perimeter in the usual way. This requires preparation of the surfaces to be soldered. Not only must the edge of the window glass be metallized, but an internal gold plating of the fiber optic tube is also advantageous to ensure a truly secure attachment. For a number of reasons, mostly related to manufacturing processes, it is advisable to allow this gold plating to extend proximally beyond the area to be soldered. Similarly, for several reasons, the metal solder used for soldering is often allowed to ooze out of the solder joint proximally.

[0008] After the window has been soldered, highly reflective surface areas formed by the gilding and / or the solder result on the inside of the fiber tube in the area between the window and the lens, which lead to disturbing reflections that can radiate from the side into the beam path and towards the viewer's eye.

[0009] As mentioned earlier, JP H03-81716A discloses a ring as a spacer tube. However, this does not allow for particularly precise adjustment of the lens and, at the same time, facilitates the assembly of the endoscope. The present invention aims to achieve this, thereby also improving the optical properties of the endoscope.

[0010] According to the invention, support between the lens and the window is provided by an intermediate spacer tube, which is supported by both the window and the lens. The lens is arranged in a lens tube, which is mounted within the fiber tube and supported by the spacer tube. The lens tube has a reduced diameter step at its distal end, and the spacer tube rests at its distal end against the window and at its proximal end against the step where the lens tube transitions into its reduced-diameter distal end. This allows for particularly precise adjustment of the lens and simultaneously facilitates the assembly of the endoscope. This is a simple solution that is also easy to install. Furthermore, this solution eliminates the step on the inside of the fiber tube, thus eliminating the resulting reduction in diameter.The adjustment pin for the window can be enlarged in diameter, allowing for more precise installation of the window.

[0011] The spacer tube is suitable for covering any reflective surface areas that may be located on the inside of the fiber tube, so that disturbing reflections are avoided, especially when it is designed as a light-tight baffle tube according to claim 2, resulting in an optimal effect that blocks out lateral reflections.

[0012] The invention is illustrated schematically and by way of example in the drawing. It shows: Fig. 1 an axial section through the distal end region of an endoscope according to the invention, and Fig. 2 the cut of the Fig. 1 in one version of the window during its installation.

[0013] Fig. Figure 1 shows an axial section through the distal end region of an endoscope 1. This is a rigid endoscope. The depicted tube structures can therefore be made of hard plastic or, in particular, metal. An outer housing tube, working channels, and the like have been omitted for the sake of simplicity. A fiber tube 2, which houses the image-transmitting optical system, is visible. To protect the optical elements, the fiber tube 2 is sealed. A window 3 at the distal end serves this purpose, its edge 4 being soldered into the inner surface of the fiber tube 2. In the illustrated embodiment, the window 3 is designed as a wedge window. However, it can also be, as shown in Figure 2, designed as a wedge window. Fig. 2 with window 3' shows, designed as a plan window.

[0014] At a distance from window 3, a lens tube 5 is arranged in the fiber tube 2, in which a lens is mounted. In the illustrated embodiment, this lens consists of two lenses 6 and 7. Lens 6 is located distal to lens 7 and has a smaller diameter. Accordingly, the lens tube 5 also has a smaller diameter in its distal end region 8.

[0015] The image must be transmitted proximal to the lens 6, 7. Various image conductors, such as a relay lens system, can be used for this purpose, or an electronic image sensor can be arranged directly behind the proximal lens 7 of the objective. In the illustrated embodiment, however, a fiber optic image conductor 9 is provided, consisting of a large number of parallel optical fibers, which transport the image from the lens 6, 7 in the proximal direction.

[0016] The objective tube 5 can be relatively short, only in the area of ​​the objective 6, 7, or, as shown, extend over the length of the fiber optic conductor 9.

[0017] To ensure optimal optical properties, the lens 6, 7 in the endoscope 1 must be firmly adjusted, particularly with regard to its distance from the window 3. The invention provides for this purpose a distance device in the form of a spacer tube designed as a baffle tube 10, which, as Fig. Figure 1 shows that the objective tube 5 is supported with its distal end against window 3 and with its proximal end against the shoulder where the objective tube 5 transitions into its reduced-diameter distal end section 8. In this way, the objective is supported relative to window 3. The secure contact of the objective tube 5 with the aperture tube 10 and its contact with window 3 can be ensured, for example, by means of spring action from the proximal end of the fiber optic cable 9 or the objective tube 5.

[0018] To secure the radial position of the lens, a projection 11 can be provided on the outside of the lens tube 5, which can be designed, for example, as a circumferential flange, as shown.

[0019] The baffle tube 10 must be designed without holes to prevent lateral interference that may arise from reflective surface areas that may be present on the inner surface 12 of the fiber tube 2 near the window 3. The baffle tube 10 effectively blocks these reflections and is itself non-reflective because it is mounted cleanly and without any stress from the soldering process after the soldering is complete.

[0020] Fig. Figure 1 shows optical fibers 13 located outside the fiber tube 2. These fibers are connected proximally to a light source (not shown) and emit light onto the observation area from their distal end face. The optical fibers 13 can be omitted in special designs. Other structural elements adjoining the fiber tube 2 externally, such as a working channel, external tube structures, and the like, have been omitted for the sake of clarity.

[0021] Fig. 2 shows the fiber tube 2 of the Fig. 1 with a window 3', which in one version is designed as a flat window on both sides.

[0022] The adjustment process used to ensure the precise position of window 3' during soldering is also illustrated here. For this purpose, an adjustment mandrel 14 is inserted into the still empty fiber tube 2. Its end face 15 is adapted to the respective window 3 or 3'. In the case of window 3', the end face 15 is perpendicular to the axis of the fiber tube 2, while in the case of the wedge-shaped window 3, it is angled to match the sloping inner surface of window 3. The adjustment mandrel 14 is advanced into the fiber tube 2 until its end face 15 fully engages and securely holds the unsoldered window. In this position, the window can now be soldered along its circumferential edge 4 without any positional deviations.

[0023] After soldering is complete, the adjusting mandrel 14 is pulled out and the in Fig. 1. The optical internal components shown are mounted.

[0024] Instead of the adjusting mandrel 14, in an embodiment not shown, a stop on the fiber tube 2 can also be used as a guide for adjusting the window during soldering. Such a stop can, for example, be created by screwing it in from the distal end of the fiber tube 2. Reference symbol list: 1 endoscope 2 Fiber tube 3.3' windows 4 Edge area 5 lens tube 6 lens 7 lens 8 End area 9 Fiber optic conductors 10 Blind tube 11 lead 12 interior surface 13 optical fibers 14 Adjusting mandrel 15 Front surface

Claims

[1] Rigid endoscope (1) with a fiber tube (2) whose distal end is closed by a window (3, 3') and with an objective lens (6, 7) arranged in the fiber tube (2), which is held at a distance from the window (3) by a spacer device (10), wherein the spacer device is designed as a spacer tube (10) which is supported distally on the window (3) and proximally on the objective lens (6, 7), characterized by , that the objective (6, 7) is arranged in an objective tube (5, 8) via which the objective (6, 7) is mounted in the fiber tube (2) and supported on the spacer tube (10), that the objective tube (5, 8) is formed in its distal end region (8) by forming a step with a smaller diameter and that the spacer tube (10) is supported with its distal end on the window (3, 3') and with its proximal end on the step at which the objective tube (5, 8) transitions into its diameter-reduced distal end region (8). [2] Endoscope according to claim 1, characterized by , that the spacer tube is designed as a light-tight baffle tube (10).

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