JPH04324813A - Endoscope - Google Patents

Abstract

PURPOSE:To prevent breakage of bundle of optical fibers in the insertion part without enlarging the outside dia. of a curved pipe even in case it is curved repetitively in two directions with different curving angles. CONSTITUTION:A plurality of optical fiber bundles covered with a sheath tube 8 are inserted in the insertion part consisting of a coupling of a flexible pipe and a curved pipe, the latter being curved in two directions with different angle of curving, and thus an endoscope is constructed. That of the optical fiber bundles 42b which is situated on the side with smaller curving angle direction among the two directions, at least in the curved pipe 4, is prevented from breakage with the aid of a breakage preventing means.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to endoscopes, and in particular,
The present invention relates to an endoscope in which a plurality of optical fiber bundles covered with a protective tube are inserted into an insertion section consisting of a flexible tube and a curved tube.

0002

2. Description of the Related Art Conventionally, a relatively fragile optical fiber bundle built into an insertion section of an endoscope is usually covered with a flexible protective tube around its outer periphery to prevent breakage or the like. In particular, the curved tube portion of the insertion section is subject to complicated and large movements, and therefore the optical fiber bundle is likely to break.

For example, in Japanese Utility Model Application Publication No. 58-117602, the outer periphery of an optical fiber bundle located in a bending tube portion is coated with a protective tube in a double layer to prevent forceps, etc., from being inserted into a forceps channel during bending. While this prevents the optical fiber bundle in the curved tube section from breaking due to pushing force or bending force during bending, the protective tube covering the outer periphery of the optical fiber bundle located in the flexible tube section other than the curved tube is made with a single layer. In this way, the diameter of the insertion portion is reduced.

Furthermore, in Japanese Utility Model Application Publication No. 184508/1983, the inner diameter of the curved tube portion of the protective tube coated around the outer periphery of the optical fiber bundle is made smaller than the inner diameter of the flexible tube portion. The density of the optical fiber bundle is increased and it is made relatively stiff to prevent it from breaking.

Furthermore, in Japanese Utility Model Application Publication No. 63-77001, the filling factor of the optical fiber bundle in the curved tube section is made lower than that in the flexible tube section, thereby reducing the curvature of the optical fiber bundle in the curved tube section. This facilitates axial movement and prevents the optical fiber bundle from breaking at the curved tube portion.

[0006]

By the way, in an apparatus in which a plurality of optical fiber bundles are inserted into an insertion section, when a bending tube is bent, among the optical fiber bundles in the bending tube section, the optical fiber bundles are located on the outer circumferential side (from the neutral axis of the bending tube). (Hereinafter, it will simply be referred to as the curved outer circumferential side.)
Those located on the inner circumferential side of the curved tube's neutral axis (hereinafter simply referred to as the curved inner circumferential side) are pushed toward the operating section by compressive force. .

[0007] Particularly in an endoscope in which the bending tube can be bent in two opposite directions, one optical fiber bundle is subjected to both the tensile force and the compressive force. That is, when the curved tube is curved in one of the two directions, for example, the optical fiber bundle located on the outer periphery of the curve and pulled toward the distal end of the insertion section will then bend the curved tube in the other direction. Since it is located on the inner circumferential side of the curve, it receives a compressive force and is pushed out toward the operating section.

[0008] Therefore, the optical fiber bundle in the curved tube portion is repeatedly subjected to the contradictory forces of the tensile force and compressive force, for example, by repeatedly changing the bending direction of the curved tube, and also moves in the axial direction of the insertion section. It buckles and breaks when a force that impedes this movement is applied.

[0009] Such breakage occurs particularly in endoscopes in which the bending tube can be bent in two directions with different maximum bending angles.
When the bending tube is bent in the direction in which the maximum bending angle is large, it tends to occur in the optical fiber bundle located on the outer circumferential side of the bend. For example, if the bending tube is bent in a direction with a large maximum bending angle, compared to a case where it is bent in a direction with a small maximum bending angle,
It is difficult to insert forceps or the like into the forceps channel, and if the forceps or the like is pushed into the forceps channel against this insertion resistance, the optical fiber bundle located on the curved outer circumferential side is compressed by the pushing force. Due to this compression action and the above-mentioned repeated curving of the curved tube in two directions, when the curved tube is bent in the direction with a larger maximum bending angle, the optical fiber bundle located on the outer circumference side of the curve is It is more likely to break than the optical fiber bundle located on the side. There are several other possible causes for the optical fiber bundle located on the outer circumference of the curved tube to break, but in order to solve these problems, conventional breakage prevention means have been applied to all optical fiber bundles in the curved tube section. Since this method is applied to a curved tube, there is a risk that the outer diameter of the curved tube will often become large.

The present invention has been made in view of the above-mentioned circumstances, and its object is to maintain the outer diameter of the curved tube even when the curved tube is repeatedly bent in two directions with different bending angles. An object of the present invention is to provide an endoscope that can prevent breakage of an optical fiber bundle within an insertion section without increasing the size of the endoscope.

[0011]

[Means for Solving the Problems] In order to solve the above problems, the present invention includes inserting a plurality of optical fiber bundles covered with exterior tubes into an insertion section formed by connecting a flexible tube and a curved tube.
In an endoscope in which the bending tube curves in two directions with different bending angles, breakage of an optical fiber bundle located in the direction with the smaller bending angle of the two directions with different bending angles is prevented at least within the bending tube. A breakage prevention means is provided to prevent the breakage.

0012

[Operation] Even if the bending tube is repeatedly bent in two directions with different bending angles, the optical fiber bundle located in the direction with the smaller bending angle is prevented from being broken by the breakage preventing means.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show a first embodiment of the present invention. As shown in FIG. 2, the endoscope 1 of this embodiment has an endoscope main body composed of an insertion section 3 and an operation section 2, and the operation section 2 includes an eyepiece section 2a and an operation lever 2b. A forceps port 2c communicating with the forceps channel 26, etc. are provided. Further, the insertion section 3 includes a flexible section 6, a curved section 4, and a distal end section 5, and a jacket tube 8 is fitted around the outer periphery thereof. The curved portion 4 has the same diameter as the curved portion of an existing endoscope, and is moved in two directions (hereinafter, one of the two directions is referred to as the UP direction and the opposite direction by the operation lever 2b of the operation section 2). The other direction is called the DOWN direction.) The bending portion 4 has a gap 29 (
(See FIG. 3(b)), and by placing restrictions on the pulling operation of the operating wire 14 connected to the bending piece 10, the maximum bending angle in the UP direction can be reduced.
It is designed to be larger than that in the direction.

As shown in FIG. 3(b), the curved portion 4 is
For example, bending pieces 10 are arranged inside a rubber-like outer tube 8 in the longitudinal axis direction of the insertion section 3. Further, the bending pieces 10 are rotatably connected to each other by rivets 12 at their adjacent ends, so that the bending pieces 10 can be bent freely. Furthermore, a pair of bending operation wires 14, 14, which are vertically biased, are inserted and disposed within the insertion portion 3, for example. The bending operation wires 14, 14 are fixed by having their tips separately attached to wire guides 18 provided at the upper and lower ends of the most advanced bending piece 10, respectively. Then, the bending operation wire 1
4 and 14 are, for example, supported between the peripheral wall of the bending piece 10 and the aperture part 20, connected to the bending piece 10, inserted through the inside of the bending part 4, and disposed in the flexible part 6. For example, guided within the flexible portion 6 by a guide pipe (not shown),
Its base end side is connected to a wire operating mechanism (not shown) operated by an operating lever 2b. Therefore, by operating the operating lever 2b and pulling one of the bending operation wires 14, 14, the bending portion 4 can be bent in that direction. At this time, the other bending operation wire 14 is let out.

The distal end portion 5 includes a distal end frame 24 made of metal, and an insulating member 22 for high frequency insulation fitted to the distal end of the distal end frame 24.

The tip frame 24 has a forceps insertion hole 32 that communicates with the forceps channel 26 and into which forceps etc. can be inserted, an image guide fiber bundle 44 and a light guide fiber bundle 42.
It has three holes 34, 36, 37 into which light from the observation optical system such as the tip portions a and 42b and the objective lens 48, etc. are incorporated. Among the three holes 34, 36, and 37, the third hole 37, which will be described later, is located on the DOWN direction side where the maximum bending angle is small, and the tip of the light guide fiber is incorporated into the third hole 37. The bundle 42b is also located over the entire length of the insertion portion 3 on the DOWN direction side where the maximum bending angle is small. In other words, the light guide fiber bundle 42
When the curved portion 4 is curved in the UP direction where the maximum curve angle is large, b is located on the outer circumferential side of the curve, and resists insertion resistance when forceps or the like is inserted into the forceps channel 26 during the bending. It is located in a region that is compressed by the pushing force of the forceps or the like.

Furthermore, the most advanced bending piece 10 among the bending pieces 10 disposed within the bending portion 4 is fixed to the tip frame 24 . Note that, in order to accommodate the wire guides 18 provided at the upper and lower ends of the most advanced bending piece 10, the tip frame 24 is provided with a first notch 74 (FIGS. 3(b) and 3(e)). reference).

The forceps channel 26 with which the forceps insertion hole 32 communicates with the outer jacket tube 28 and the outer jacket tube 2.
A channel protection coil 30 for buckling prevention is wound along the axial direction around the outer periphery of the insertion portion 3 to form the entire length of the insertion portion 3. A cap 58 fitted to the inner circumferential surface of the tip of the jacket tube 28 is fitted into the forceps insertion hole 32 and fixed with adhesive.

Further, inside the first hole 34 of the three holes 34, 36, 37, a large diameter portion 34b and a small diameter portion 34a are formed by a stepped portion 35, and the image guide fiber bundle 44 is Objective lens 4 at the tip and inside
A cylindrical lens frame 56 having 8... is incorporated. The image guide fiber bundle 44 is constructed by bundling a plurality of fibers, and a sheath tube 46 is fitted around the outer periphery except for the exposed tip. In addition, the image guide fiber bundle 44 has a cap 60 fitted to the outer periphery of the exposed tip portion, and by fitting the cap 60 to the inner peripheral surface of the small diameter portion 34a of the first hole 34, the tip frame is formed. 2
It is installed on 4. The base end side of the image guide fiber bundle 44 is inserted into the flexible part 6 through the inside of the bending pieces 10 of the bending part 4, guided into the operation part 2, and connected to the eyepiece part 2a. ing.

A cylindrical lens frame 56 and an objective lens 48 held by the lens frame 56 are provided in the first hole 34 extending forward from the tip of the image guide fiber bundle 44. . The lens frame 56 has the first hole 3
While being adhesively fixed to the inner circumferential surface of the large diameter portion 34b of No. 4,
The tip thereof becomes an extension portion 56a having a small outer diameter of the frame and projects from the first hole 34.

As shown in FIG. 3(c), the second hole 36
and a stepped portion 39 inside each of the third holes 37.
A large-diameter portion 41 and a small-diameter portion 43 are formed, into which the tips of light guide fiber bundles 42a and 42b formed by bundling a plurality of fibers are incorporated. The light guide fiber bundles 42a, 42b have outer skin tubes 40a, 40b fitted around their outer peripheries, and the exposed tips are fitted into the holes 36, 37 up to the tips of the small diameter portions 43 and fixed with adhesive. ((c) in Figure 3 is the third hole 3
A cross section around 7 is shown. ) Also, the wall thickness of the outer skin tube 40b on the outer periphery of the light guide fiber bundle 42b whose tip is incorporated in the third hole 37 located on the DOWN direction side where the maximum bending angle is small is determined by the forceps channel 2 described above.
6, and the wall thickness of the outer sheath tube 40a on the outer periphery of the light guide fiber bundle 42a, the tip of which is incorporated into the second hole 36, is supported during normal bending operation. The light guide fiber bundle is formed to be slightly thin so that it does not cause any blemishes, so that a sufficient amount of light guide fiber bundle can be inserted into the curved portion 4 to provide a sufficient amount of light for endoscopic observation. The base end side of the light guide fiber bundles 42a, 42b is connected to the bending piece 10 of the bending section 4.
It is inserted into the flexible portion 6 through the interior of the . . . , guided into the operating portion 2, and connected to a light source device not shown. Further, the rear end of the illumination lens 50 is fitted into the inner peripheral surface of the large diameter portion 41 of each hole 36, 37. Therefore, the light guide fiber bundles 42a and 42b can irradiate the illumination light from the light source device into the body through the illumination lens 50.

According to the optical observation system described above, light from the light source device (not shown) is transmitted through the light guide fiber bundle 4.
2a and 42b, the light is emitted from the distal end of the insertion section 3 and irradiated onto the irradiated object, and the reflected light from the irradiated object passes through the objective lens 48 and forms an image on the distal end surface of the image guide fiber bundle 44. The image is transmitted by an image guide fiber bundle 44 to the eyepiece 2a.
The condition of the object to be irradiated can be observed through a.

The insulating member 22 is made of plastic, ceramic, or the like, and has a first hole 54 at a portion corresponding to the forceps insertion hole 32 of the tip frame 24. Further, the insulating member 22 has the first, second and third holes 34, 36, 37 in the portions corresponding to the first, second and third holes 34, 36, 37 of the tip frame 24. It has a second hole 52 having a continuous shape. On the inner circumference of the second hole 52 at a portion corresponding to the first hole 34,
The extended tip 56a of the lens frame 56 is fitted. The most advanced objective lens 48 is fitted into the tip 56a of the lens frame 56. Also, the second
An illumination lens 50 is fitted into the inner circumferential portion of the hole 52 at a portion corresponding to the second and third holes 36 and 37 with an adhesive or the like, and the rear end of the illumination lens 50 is attached to the tip frame 24. It is located within the large diameter portion 41 of the second and third holes 36 and 37 and is in contact with the rear end portion (step portion 39) of the large diameter portion 41.

Further, as shown in FIG. 3(a), the space between the illumination lens 50 and the objective lens frame 56 is filled with a black adhesive 64 to form a partition wall 61. This prevents direct light from the illumination lens 50 from entering the objective lens 48, and also prevents the illumination lens 50 from entering the objective lens 48.
And the objective lens frame 56 is fixed with the adhesive 64.

Although the insulating member 22 is fixed to the tip frame 24 with an adhesive or the like as described above, in order to further ensure safety, a member such as a dowel pin or the like shown in FIG. 66 is inserted from the insulating member 22 to the tip frame 24 to mechanically prevent it from falling off. Furthermore, side holes 70 and 79 are provided in the insulating member 22 and the portion of the tip frame 24 through which the slip-off prevention member 66 is inserted, respectively. The part of the insulating member 22 where the side hole 70 is provided is a thick part 22a, and a second notch is formed in the part of the tip frame 24 corresponding to the thick part 22a. 71 is provided. Further, after inserting the slip-off preventing member 66, the side hole 70 is filled with a CE agent or the like. In addition, as shown in FIGS. 3(d) and (e), the tip frame 24
The relative positions of the first notch 74 and the second notch 71 along the axial direction are set to be substantially the same.

Therefore, in the endoscope 1 having the above configuration, when the wire 14 on the UP direction side is pulled by operating the operating lever 2b and the bending portion 4 is bent in the UP direction where the maximum bending angle is large, the bending The light guide fiber bundle 42b located on the outer circumferential side is pulled toward the distal end of the insertion section 3, and the light guide fiber bundle 42a, for example, located on the curved inner circumferential side is pushed out toward the operating section 2 side by a compressive force. Furthermore, when the wire 14 on the DOWN direction side is pulled to bend the bending section 4 in the DOWN direction where the maximum bending angle is small, the light guide fiber bundle 42a located on the outer circumferential side of the curve is pulled toward the distal end side of the insertion section 3. At the same time, the light guide fiber bundle 42b located on the inner circumferential side of the curve is pushed out toward the operating section 2 by the compressive force. In this way, the light guide fiber bundle 42a,
42b, etc., are repeatedly bent in two different directions, thereby repeatedly receiving contradictory forces such as the tensile force and compressive force, and move greatly in the axial direction of the insertion portion 3. Light guide fiber bundle 4 located on the DOWN direction side with a small bending angle
It is carried out vigorously in 2b. Furthermore, when the light guide fiber bundle 42b is bent in the UP direction, when a forceps or the like is inserted into the forceps channel 26, the light guide fiber bundle 42b is strongly compressed by the pushing force of the forceps or the like that resists the insertion resistance.

However, in the endoscope 1 having the above configuration, the sheath tube 40b on the outer periphery of the light guide fiber bundle 42b located on the DOWN direction side where the maximum bending angle is small does not absorb the compressive force from the forceps channel 26, etc. Since the wall thickness is large enough to withstand this, it will not break even if it is repeatedly bent in different directions and is strongly pressed by the pushing force of the forceps or the like.

In addition, the endoscope 1 of this embodiment does not increase the wall thickness of the jacket tube for all the optical fiber bundles in the curved portion 4, as in the conventional case, but instead Light guide fiber bundle 42b on the receiving DOWN direction side
Only the wall thickness of the outer sheath tube 40b on the outer periphery of the light guide fiber bundle 42a on the UP direction side is formed to be slightly thinner, so that endoscopic observation within the curved portion 4 is possible. Since the wall thickness is adjusted so that the light guide fiber bundle can be inserted in an amount sufficient to provide a sufficient amount of light for the purpose of achieving this, the outer diameter of the curved portion 4 does not become large.

The endoscope 1 of this embodiment also has first, second and third insulating members attached to the insulating member 22 as means for fixing the distal ends of the illumination lens 50 and the objective lens frame 56 to the insulating member 22. A second hole 52 having a shape in which the holes 34 , 36 , and 37 are connected is formed, and the illumination lens 50 and the tip of the objective lens frame 56 are fitted into the second hole 52 . Since the space between the objective lens frame 56 and the adhesive 64 is filled to form the partition wall 61,
First, second and third holes 3 with very close distances between each hole
This is easier than forming lenses 4, 36, and 37 separately and fixing the illumination lens 50 and objective lens frame 56 there. In other words, conventionally, when forming multiple holes with extremely close distances in the insulating member 22 by cutting, the thin-walled portions were cut during the cutting process, resulting in so-called burrs, or the holes were formed by injection molding. In this case, a very high-precision mold was required to accurately mold the walls between the plurality of holes, which was an obstacle when forming the plurality of holes, but this example It is extremely easy to form the second hole 52, and at the same time, the filled adhesive 64 becomes a partition wall 61 between the illumination lens 50 and the objective lens frame 56 by hardening, and as a result, This is similar to forming the first, second and third holes 34, 36, 37 separately and fixing the illumination lens 50 and objective lens frame 56 therein.

Furthermore, by providing the thick wall portion 22a in the insulating member 22, the side hole 70 is formed in the thick wall portion 22a to allow the slip-off preventing member 66 to be inserted therethrough, and the slip-off preventing member 66 is inserted outside the insulating member 22. Since the insulating member 22 is mechanically fixed to the distal end frame 24 by being housed inside the insulating member 22 without protruding, the fixing strength can be increased even in a small diameter endoscope, which is advantageous.

Furthermore, since the relative positions of the first notch 74 and the second notch 71 of the distal end frame 24 along the axial direction are approximately the same, the length of the detachment prevention member 66 is set to be the same as that of the insertion part built-in member. It can be made as large as possible without affecting.

[0032] In this embodiment, the maximum bending angle is small.
Breaking of the light guide fiber bundle 42b was prevented by forming the jacket tube 40b on the outer periphery of the light guide fiber bundle 42b on the OWN direction side to be thicker. It may be made heavier to increase its wall thickness. FIG. 4 shows a second embodiment of the invention.

In the endoscope 80 shown in FIG. 4A, the diameter of the jacket tube 40b on the outer periphery of the light guide fiber bundle 42b on the DOWN direction side where the maximum bending angle is small is the same as that of the light guide fiber bundle 42b on the UP direction side where the maximum bending angle is large. The light guide fiber bundle 42a is formed to have a diameter larger than that of the sheath tube 40a on the outer periphery, and the filling rate of the light guide fiber bundle 42b in the sheath tube 40b is made small, so that endoscopic observation can be carried out inside the curved portion 4. The light guide fiber bundle can be inserted in an amount sufficient to provide a sufficient amount of light.

Therefore, the endoscope 80 configured as described above reduces the axial direction of the light guide fiber bundle 42b during the bending operation by reducing the filling rate of the light guide fiber bundle 42b on the DOWN direction side where the maximum bending angle is small. Since it is easy to move, the light guide fiber bundle 42b
Buckling and breakage during the operation can be prevented as much as possible.

In addition, the second hole 36 and the third hole are formed so that a sufficient amount of light guide fiber bundle can be inserted into the curved portion 4 to provide a sufficient amount of light for endoscopic observation. Since the diameters of both tubes 40a and 40b of 37 are adjusted, the outer diameter of the curved portion 82 does not become large.

Furthermore, the endoscope 90 shown in FIG. 4(b) has the following features:
By increasing the degree of constriction of the aperture part 20 of the bending piece 10 in the bending part 92, the light guide fiber bundle 42b on the DOWN direction side, where the maximum bending angle is small, is pushed out toward the operation part 2 and meandered during bending. At this time, the light guide fiber bundle 42b is prevented from climbing over the constriction part 20.

Therefore, according to the endoscope 90 having the above configuration, since the aperture section 20 guides the light guide fiber bundle 42b, the light guide fiber bundle 42b is pushed toward the operating section 2 and meandered during bending. Even if
The light guide fiber bundle 42b does not get over the constriction part 20 and buckle, and does not break.

FIG. 5 shows a third embodiment of the present invention. In the endoscope 100 of this embodiment, aperture parts 20 are provided every other time on the UP side of the bending pieces 10 in the bending part 102, and aperture parts 20 are provided on all the pieces on the DOWN side. According to this, the same effects as the endoscope 90 shown in FIG. 4(b) can be obtained.

FIG. 6 shows a fourth embodiment of the present invention. In the endoscope 110 of this embodiment, aperture parts 20 are provided every other time on the UP side of the bending piece 10 in the bending part 112, and every other aperture part 20 is provided on the DOWN side. . When the aperture section 20 is provided at every other bending piece 10, the light guide fiber bundles 42a, 42 in the bending piece 10 are pushed out toward the operating section 2 and meander.
While the meandering degree of b becomes steeper, the aperture part 2
0 is provided at every second bending piece 10, and the endoscope 110 having the above configuration is provided with aperture portions 20 at every second bending piece 10 on the DOWN side. When the light guide fiber bundle 42b on the DOWN side is pushed out toward the operating section 2 during bending,
Since the light guide fiber bundle 42b is designed to meander in a small circular arc, the light guide fiber bundle 42b will not buckle and break.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but may be constructed by combining the above-mentioned embodiments, for example.

By the way, as the end frame 24 and the insulating member 22 become smaller as the diameter of the endoscope becomes smaller, it becomes very difficult to use a pin as the falling-off prevention member 66 that prevents the insulating member 22 from falling off. However, the endoscope 12 shown in FIG.
0, this problem can be satisfactorily solved.

FIG. 7(a) shows the vicinity of the distal end of the endoscope 120. Note that the same members as in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed explanation thereof will be omitted. Reference numeral 121 denotes a cylindrical tip frame made of a metal material, and inside the tip frame 121, as shown in FIG. , a first hole 34 into which an objective lens 48, a laser guide fiber bundle 44, etc. are installed, and second and third holes 36 into which a light guide fiber bundle (not shown) is installed.
, 37, and a through hole 126 as an air/water supply hole. The through hole 126 serving as the air/water supply hole communicates with the air/water pipe 126a, so that air and water can be supplied from the air/water nozzle 126b.

The insulating member 123 is connected to each hole 3 of the tip frame 121.
Holes are provided at positions corresponding to 2, 34, 36, 37, and 126, respectively. Further, the rear end of the insulating member 123 is brought into close contact with the tip of the jacket tube 8. Also,
As shown in FIG. 7(d), a claw-like portion 130 is formed at the rear end of the insulating member 123 to fit loosely into a groove 132 formed in an extra space on the outer peripheral surface of the tip frame 121. Then, in order to fix the insulating member 123 to the tip frame 121,
The claw-shaped portion 130 is loosely fitted into the groove 132, and the tip of the jacket tube 8 is fitted and fixed thereon with adhesive.
It is only necessary to tighten and fix the outer periphery of the holder with a thread 124.

According to the above structure, the insulating member 123 is tightened and fixed to the distal end frame 121 by fitting the claw-like portions 130 into the grooves 132 of the distal end frame 121. Compared to the case where it is fixed only by adhesive, the fixing force is greater and it can prevent it from falling off. Furthermore, even if the tip frame and the insulating member are downsized as the diameter of the endoscope becomes smaller, it is possible to easily and reliably prevent the insulating member 123 from coming off without using a pin. Furthermore, since the groove 132 is formed in the extra space after the observation optical system such as the objective lens 48 and the fiber 44 is arranged, it does not have any adverse effect on the observation optical system.

FIG. 8 also shows the insulating member 12 in FIG.
This is a modification of the loosely fitting portion between the claw-like portion 130 and the groove 132 of the tip frame 121 in No. 3, in which the claw-like portion 130 is provided with a convex portion 140,
When the claw-like portion 130 is loosely fitted into the groove 132, the convex portion 14
0 protrudes from the outer peripheral surface of the tip frame 121. According to this configuration, the adhesion between the claw-like portions 130 and the jacket tube 8 is improved, and the tightening by the threads 124 can be performed reliably and firmly. Also, Figure 9
As shown in , if the groove 132 of the tip frame 121 is formed into a tapered groove 133 that gradually slopes toward the inside of the tip frame 121 as it goes toward the rear end side, the claw-like portion 130 is formed into the groove 13.
2, the claw-like portion 130 is attached to the tip frame 121.
This allows the insulating member 123 to be firmly held in place by the insulating member 123.

[0046]

[Effects of the Invention] As explained above, according to the present invention,
Even if the bending tube is repeatedly bent in two directions with different bending angles, it is possible to prevent the optical fiber bundle in the insertion section from breaking without increasing the outer diameter of the bending tube.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a curved portion of an endoscope showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an endoscope showing a first embodiment of the present invention.

FIG. 3(a) is a front view of the distal end of an endoscope showing the first embodiment of the present invention, the left half of FIG. The right half of b) is a side cross-sectional view taken along line A-O-B in (a), (c) is a cross-sectional view taken along line C-C in (a), and (d) is a cross-sectional view taken along line C-D in (b). (e) is a cross-sectional view taken along line EE in (b).

FIG. 4 shows a second embodiment of the present invention, in which (a) is a cross-sectional view of a curved part of an endoscope in which the filling rate of light guide fibers is changed, and (b) is a sectional view of a constricted part of the curved part. FIG. 3 is a cross-sectional view of a curved portion of an endoscope in which the curve is changed.

FIG. 5 is a side sectional view of an endoscope showing a third embodiment of the present invention.

FIG. 6 is a side sectional view of an endoscope showing a fourth embodiment of the present invention.

[Fig. 7] (a) is a side sectional view of the endoscope, (b) is a front view of the tip frame when there is no built-in observation optical system inside;
(c) is a sectional view taken along line FF in (a), and (d) is a schematic diagram showing how the insulating member is attached to the tip frame.

8 is a sectional view showing a state in which an insulating member showing a modification of FIG. 7 is attached to the tip frame; FIG.

9 is a side sectional view showing a state in which an insulating member showing a modification of FIG. 7 is attached to the tip frame; FIG.

[Explanation of symbols]

1, 80, 90, 100, 110... Endoscope 4... Curved portion 40a, 40b... Outer tube 42a, 42b... Light guide fiber 44... Image guide fiber

Claims (1)

[Claims] 1. An endoscope in which a plurality of optical fiber bundles covered with an exterior tube are inserted into an insertion section formed by connecting a flexible tube and a bending tube, and the bending tube curves in two directions with different bending angles. An endoscope characterized in that a breakage preventing means is provided for preventing breakage of the optical fiber bundle located in the direction with the smaller bending angle of the two directions having different bending angles, at least within the curved tube.