JPH04244130A - Endoscope - Google Patents

Abstract

PURPOSE:To eliminate the generation of uneven illumination and to prevent a possible step on an end face of an inserting part by turning illumination light to a circular stripe pattern in an endoscope in which an outgoing end face of the illumination light of a light guide is arranged circular surrounding an observation window, especially like a fine-diameter endoscope. CONSTITUTION:A tip cap 16 is crowned so as to cover an illumination light outgoing end 11a of at least a light guide 11 at the tip of an inserting part 10 and an internal surface of the tip cap 16 is provided with a lens action. A diffusion part 17 is formed to diffuse the illumination light to be emitted from the light guide.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is applicable to a bronchoscope, an angioscope, etc., which is inserted along an extremely narrow insertion path.
This relates to endoscopes suitable for performing examinations, diagnosis, etc.

0002

[Prior Art] Endoscopes are inserted into the bronchi, blood vessels, etc., or from the papilla of Fata in the duodenum to the hepatic duct, pancreatic duct, etc. for examinations and diagnoses.The insertion path is extremely narrow. For this reason, the diameter of the insertion portion is extremely thin, ranging from 3 to 4 mm or less. Due to the structural limitations of such an ultra-thin endoscope,
It is for observation only. Therefore, the structure of the distal end of the insertion portion is as shown in FIG.

As is clear from the figure, a light guide 2 and an image guide 3 are housed inside a flexible part 1, and a tip main body 4 is provided at the tip of the flexible part 1. attached. The tip main body 4 is provided with a lens barrel 5, and an objective lens 6 is mounted in the lens barrel 5, and the end surface of the image guide 3 is placed at the imaging position of the objective lens 6. 3a is coming. On the other hand, the light guide 2 is formed in an annular shape so as to surround the lens barrel 5, and the illumination light output end 2a, which has become annular in this way, is directly connected to the tip main body. It is exposed from 4. In order to keep the output end 2a of the light guide 2 airtight, the output end 2a of the light guide 2 is hardened with adhesive and the end surface of the output end 2a is polished.

0004

[Problems to be Solved by the Invention] By the way, in the ultra-fine endoscope of the prior art described above, the light emitting end 2a of the light guide 2 is annular, so that light is emitted from the light guide 2. The illumination light forms a ring and is irradiated toward the subject. Therefore, the central portion is dark, and bright and dark portions are concentrically formed in stripes from this dark portion, resulting in uneven illumination. In particular, this illumination unevenness becomes noticeable at a position relatively close to the subject, making it extremely difficult to see the subject, which may impede its observation. In addition, it is extremely troublesome to accurately polish the output end 2a of the light guide 2, and even if the polishing is done precisely, it is impossible to prevent a step from forming at the tip. Therefore, there is also the problem that a step is formed at the tip, making insertion difficult. Furthermore, it may not be possible to reliably achieve an airtight structure if the end surface treatment is performed only with an adhesive.

The present invention has been made in view of the above points, and its object is to provide an endoscope that has no uneven illumination and has an extremely smooth end surface of the insertion section. It's about doing.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a distal end cap that is attached to the distal end of the insertion section so as to cover at least the output end of the light guide, The light guide is characterized by a configuration in which a diffusion portion is formed to diffuse the illumination light emitted from the light guide.

[0007]

[Function] By adopting this configuration, first, it becomes possible to irradiate uniform illumination light toward the subject by the action of the diffusion part formed on the tip cap, thereby preventing the occurrence of uneven illumination. You will be able to do this. Furthermore, if the light guide is exposed on the distal end surface of the insertion section, it is impossible to prevent a step from forming between the light guide and the distal end body and lens barrel.
By providing a distal end cap to cover this light guide, the number of steps can be reduced, and as a result, the distal end surface of the insertion portion is made smoother, making the insertion operation extremely easy. Furthermore, there is no need to fill the light guide's output end with adhesive, or even if it does, it can be as simple as ensuring its shape retention, which simplifies end surface treatment. can.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows the outer shape of the distal end portion of the insertion section of the endoscope, and FIG. 3 shows its cross section. As is clear from these figures, most of the insertion section 10 is made up of the flexible tube 1.
A tip ring 10b formed of a hard pipe is inserted into the tip of the flexible tube 10a to form a hard portion. In addition, this flexible tube 1
An angle portion may be provided between the portion 0a and the portion of the tip ring 10b to orient the tip surface in a desired direction.

A light guide 11 and an image guide 12 are inserted into the insertion section 10 described above, and a lens barrel 14 containing an objective lens 13 is disposed therein. The imaging surface 12a of the image guide 12 is the lens barrel 14.
It faces the image forming position of the objective lens 13 inside. On the other hand, the light guide 11 is formed in a ring shape within the tip ring 10b so as to surround the lens barrel 14. Then, the output end 1 of this light guide 11
1a is annular and is provided so as to surround the lens barrel 14. Regarding the above points, there is no particular difference from the prior art described above.

Reference numeral 16 denotes a tip cap, which is made of transparent glass or plastic and includes a circumferential body portion 16a and an annular portion 16b integrally connected to the tip portion of the sliding portion 16a. It is configured to have A stepped portion is formed in the circumferential body portion 16a, and a reduced diameter portion of this stepped portion is inserted into the tip ring 10b, and the stepped portion is abutted against the end surface of the tip ring 10 and the flexible tube 10a. , fixed with adhesive or the like. Further, the lens barrel 14 is inserted into the annular portion 16b that constitutes the distal end surface portion. And this annular part 1
A loop-shaped arcuate groove 17 is formed over the entire circumference of the inner surface of the light guide 11 at the portion facing the output end 11a of the light guide 11. As a result, the annular portion 16b functions as a lens and the light emitting end 11a faces the light guide 11. The illumination light emitted from the emitting end 11a of the guide 11 is diffused.

With this configuration, the illumination light emitted toward the subject from the output end 11a of the light guide 11 is transmitted by the lens action of the arcuate groove 17 formed on the inner surface of the annular portion 16b of the tip cap 16. It is spread,
This is convenient for observation because the entire subject can be illuminated almost uniformly and uneven illumination can be prevented. In addition, by keeping the joint part of the tip cap 16 to the flexible tube 10a and the tip ring 10b and the joint part with the lens barrel 14 completely airtight with a sealing material or the like,
There is no need to harden the output end 11a of the light guide 11 with adhesive and precisely polish the end surface, and even if it hardens with adhesive, the inside of the insertion section 10 can be airtight without any particularly strict treatment. can be held. Moreover,
Although there is a joint between the lens barrel 14 and the end cap 16 and a joint with the objective lens 13 at the distal end surface of the insertion section 10, there is no other step and the structure is smooth. , the insertion operability is also improved.

[0012] In addition to the above-mentioned diffusion part for diffusing the illumination light, as shown in FIG. It can also be formed by providing a large number of concave spherical parts 21, and even if the inner surface of this annular part 20b is formed into a rough surface, the effect of diffusing the illumination light can be exerted. Furthermore, as shown in FIG. 5, in order to prevent illumination light from directly entering the objective lens 31 inside the annular portion 30b of the tip cap 30, a light shielding ring 33 having the same diameter as the lens barrel 32 is installed. The outermost lens 31 that constitutes the objective lens 31
It is also possible to integrally mold the body part 30a of the distal end cap 30 with the insertion part 1.
It can be easily assembled by simply fitting it into the tip ring 10b at 0 and fixing this fitting portion with adhesive or the like.

[0013]

As explained above, the present invention provides a distal end cap that is attached to the distal end of the insertion section so as to cover at least the output end of the light guide, and a distal end cap that covers the illumination emitted from the light guide. Since the structure is configured to form a diffusion part to diffuse the light, the illumination light emitted from the light guide can be diffused and illuminated almost uniformly onto the subject, improving observation accuracy. At the same time, it eliminates the step at the distal end of the insertion tube, making it easier to insert the insertion tube into the body, ensuring airtightness inside the insertion tube, and leaving the output end of the light guide exposed. Since there is no need to perform strict end face treatment as in the case of the conventional method, the processing can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the distal end portion of an insertion section of an endoscope in the prior art.

FIG. 2 is an external view of a distal end portion of an insertion section of an endoscope showing a first embodiment of the present invention.

FIG. 3 is a cross-sectional view of FIG. 2;

FIG. 4 is a half-sectional view of the tip cap, seen from inside, showing a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of the distal end portion of the insertion section of an endoscope showing a third embodiment of the present invention.

[Explanation of symbols]

10 Insertion part 10a Soft part 10b Tip ring 11 Light guide 12 Image guide 14, 25 Lens barrel 16, 20, 30 Tip cap 16a, 20a, 30a Circumference of trunk 16b, 20b, 30b Annular part 17 Arc groove 21 Concave spherical part

Claims (1)

[Claims] 1. An endoscope having an observation window at the distal end of the insertion section, and in which the illumination light emitting end of the light guide faces the observation window so as to surround the observation window. An endoscope characterized in that a tip cap is attached to cover at least an output end of the light guide, and a diffusion portion for diffusing illumination light emitted from the light guide is formed in the tip cap. mirror.