JP2004016455A - Distal end of endoscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a satisfactory observation image free from a flare in a distal end of an endoscope where a surface of an illumination window and that of an observation window are covered with a same transparent cover. <P>SOLUTION: In the distal end of the endoscope where the illumination window 4 for emitting illumination light and the observation window 3 for taking in an optical image to an objective optical system 5 are arranged side by side at the distal end of an insertion part and the surface of the illumination window 4 and that of the observation window 3 are covered with the same transparent cover 11, a surface of a part of the cover 11 covering the illumination window 4 is formed in the state of a projecting surface to prevent light reflected by an inner surface of the projecting surface part 12 of the cover 11 in illumination light emitted from the illumination window 4 from advancing outward from an area of the the projecting surface part 12 in a thickness of the cover 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a distal end portion of an endoscope, and more particularly, to a distal end portion of an endoscope in which an illumination window and an observation window provided at a distal end of an insertion portion are covered by the same transparent cover.
[0002]
[Prior art]
In recent years, there is an increasing need to reliably prevent infection from patient to patient via an endoscope.
[0003]
As a countermeasure, it is recommended to provide a detachable watertight sheath for the insertion section of the endoscope, use the endoscope covered with the sheath, and replace the sheath with a new one after use. This is one powerful means. In such a case, the sheath portion corresponding to the surfaces of the illumination window and the observation window must be formed transparent.
[0004]
However, when the surfaces of both windows are covered with one continuous transparent cover, for example, as shown in FIG. 4, the illumination light emitted from the illumination window 101 repeatedly reflects within the thickness of the transparent cover 102. The light enters the observation window 103 and ghosts and flares occur in the observation visual field.
[0005]
Therefore, conventionally, a transparent cover is gradually formed, for example, from the illumination window side to the observation window side, and when the light emitted from the illumination window repeats reflection in the direction toward the observation window side in the thickness of the transparent cover, the reflection angle gradually decreases. So as not to reach the observation window (Japanese Patent No. 2868228).
[0006]
[Problems to be solved by the invention]
However, as described above, even if the transparent cover is formed gradually thinner, for example, from the illumination window side to the observation window side, light emitted from the illumination window is diffused in other directions in the transparent cover and the thickness of the transparent cover is reduced. The reflected light flies around, and the entire inside of the transparent cover is illuminated and brightened, resulting in a flare that reduces the brightness of the observed image.
[0007]
Therefore, the present invention provides a method for manufacturing a front end of an endoscope in which the surface of an illumination window and the surface of an observation window are covered with the same transparent cover, and a favorable observation image without flare can be obtained. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the distal end portion of the endoscope according to the present invention has an illumination window for emitting illumination light and an observation window for taking a light image into the objective optical system, which are arranged side by side at the distal end of the insertion portion. At the tip of the endoscope in which the surface of the window and the surface of the observation window are covered with the same transparent cover, the surface of the portion of the transparent cover that covers the illumination window is formed into a convex shape, and the light is emitted from the illumination window. Light of the illumination light reflected on the inner surface of the convex portion of the transparent cover is prevented from going outward from the region of the convex portion in the thickness of the transparent cover.
[0009]
Note that the convex surface may be a spherical or aspheric curved surface, or the like, and the transparent cover may be formed thinner at the outer edge of the convex portion than at its periphery.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a distal end portion of an insertion section flexible tube of an endoscope. An observation window 3 and an illumination window 4 are arranged side by side on a distal end surface of a distal end main body 2 connected to the distal end. I have. The illumination window 4 has a concave lens fitted therein.
[0011]
An objective optical system 5 is arranged inside the observation window 3, and an image incident surface of the image guide fiber bundle 6 (or an imaging surface of the solid-state image sensor) is arranged at a position where the object is projected by the objective optical system 5. The emission end of the light guide fiber bundle 7 is arranged inside the illumination window 4.
[0012]
Reference numeral 10 denotes a covering sheath that is detachably covered on the insertion portion flexible tube 1, and the distal end portion is made of a transparent plastic such as polypropylene or polyethylene, which covers the distal end surface of the distal end body 2. The transparent cover 11 is attached, and the observation window 3 and the illumination window 4 are in close contact with each other by the same transparent cover 11.
[0013]
The surface of the portion of the transparent cover 11 covering the illumination window 4 (at least the portion where the illumination light emitted from the illumination window 4 reaches) is formed in a convex shape, and in this embodiment, the convex portion is formed. Reference numeral 12 is formed in a spherical shape.
[0014]
As a result, of the illumination light emitted from the illumination window 4, the light reflected on the inner surface of the convex portion 12 of the transparent cover 11 and returned into the convex portion 12 of the transparent cover 11 has a thickness within the thickness of the transparent cover 11. It does not go outward from the area of the convex portion 12.
[0015]
In addition, as shown by A in the figure, the light reflected outward at a position near the center of the convex portion 12 also repeats reflection in the convex portion 12 and approaches the outer edge of the convex portion 12 as it approaches. , The reflection direction changes inward.
[0016]
In order to theoretically completely eliminate light leakage outside the region of the convex portion 12, the radius of curvature of the convex portion 12 needs to be smaller than a certain value. It depends on the maximum exit angle of the illumination light to be emitted, the radius of curvature of the concave lens arranged in the illumination window 4, the refractive index of the material forming the transparent cover 11, and the like. Should be set.
[0017]
At the distal end of the endoscope of the embodiment configured as described above, the illumination light emitted from the illumination window 4 is reflected by the inner surface of the convex portion 12 of the transparent cover 11 and returned into the transparent cover 11. Since the light does not ultimately go outward from the area of the convex portion 12 in any direction, the occurrence of flare due to the internal reflection on the transparent cover 11 is almost completely eliminated, and good observation with good contrast through the observation window 3 is achieved. An image can be obtained.
[0018]
The present invention is not limited to the above embodiment. For example, the convex portion 12 does not necessarily have to be a spherical surface, but may be an elliptical surface or another aspherical curved surface (for example, a parabolic surface) as shown in FIG. Etc.).
[0019]
As shown in FIG. 3, by forming the transparent cover 11 at the outer edge portion of the convex portion 12 so as to be thinner than the periphery thereof, light leakage from the region of the convex portion 12 to the outside can be cut at that portion as well. And contribute to flare reduction.
[0020]
【The invention's effect】
According to the present invention, the surface of the portion of the transparent cover covering the illumination window is formed in a convex shape, and of the illumination light emitted from the illumination window, the light reflected on the inner surface of the convex portion of the transparent cover is used as the transparent cover. By avoiding outward from the area of the convex part in the thickness of the thickness, even if the surface of the illumination window and the surface of the observation window are covered with the same transparent cover, a good observation image without flare can be obtained. it can.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a distal end portion of an endoscope according to a first embodiment of the present invention.
FIG. 2 is a side sectional view of a distal end portion of an endoscope according to a second embodiment of the present invention.
FIG. 3 is a side sectional view of a distal end portion of an endoscope according to a third embodiment of the present invention.
FIG. 4 is a side sectional view of a distal end portion of a conventional endoscope.
[Explanation of symbols]
2 tip end part 3 observation window 4 illumination window 5 objective optical system 10 covering sheath 11 transparent cover 12 convex part

Claims (3)

An illumination window for emitting illumination light and an observation window for taking a light image into the objective optical system were arranged at the tip of the insertion section, and the surface of the illumination window and the surface of the observation window were covered with the same transparent cover. At the tip of the endoscope,
The surface of the portion of the transparent cover that covers the illumination window is formed in a convex shape, and of the illumination light emitted from the illumination window, the light reflected on the inner surface of the convex portion of the transparent cover is the light of the transparent cover. A distal end portion of the endoscope, wherein the end portion does not extend outward from the region of the convex portion in the thickness. The distal end portion of the endoscope according to claim 1, wherein the convex surface is a spherical or aspheric curved surface. 3. The distal end portion of an endoscope according to claim 1, wherein the transparent cover is formed to be thinner at an outer edge portion of the convex portion than at a periphery thereof.

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