JP4130940B2 - End of the endoscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an endoscope distal end, and more particularly to an endoscope distal end in which an illumination window and an observation window provided at the distal end of an insertion portion are covered with the same transparent cover.
[0002]
[Prior art]
In recent years, there has been an increasing need to reliably prevent infection from patient to patient via an endoscope.
[0003]
As a countermeasure, a removable water-tight sheath is provided for the insertion portion of the endoscope, and the endoscope is used in a state where the sheath is covered, and the sheath is replaced with a new one after use. It is an effective means. In such a case, the sheath portions corresponding to the surfaces of the illumination window and the observation window must be transparent.
[0004]
However, when the surfaces of both windows are covered with a continuous transparent cover, the illumination light emitted from the illumination window 101 is repeatedly reflected within the thickness of the transparent cover 102, as shown in FIG. Incident light enters the observation window 103 and ghosts and flares occur in the observation field.
[0005]
Therefore, conventionally, when the transparent cover is formed so as to be gradually thinner from the illumination window side to the observation window side, and the light emitted from the illumination window is repeatedly reflected in the direction toward the observation window within the thickness of the transparent cover, the reflection angle becomes gradually smaller. Thus, the observation window was not reached (Japanese Patent No. 2868228).
[0006]
[Problems to be solved by the invention]
However, even if the transparent cover is gradually thinned, for example, from the illumination window side to the observation window side as described above, the light emitted from the illumination window diffuses in the other direction in the transparent cover and the thickness of the transparent cover is reduced. The reflected light flew over and the entire transparent cover was illuminated and brightened, resulting in a flare that lowered the brightness of the observed image.
[0007]
In view of this, the present invention provides a distal end portion of an endoscope capable of obtaining a good observation image without flare at the distal end portion of the endoscope in which the surface of the illumination window and the surface of the observation window are covered with the same transparent cover. 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 of 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 arranged side by side at the distal end of the insertion portion. At the distal end of the endoscope where the surface of the window and the surface of the observation window are covered with the same transparent cover, the surface of the portion that covers the illumination window of the transparent cover is formed in a convex shape and emitted from the illumination window In the illumination light, the light reflected by the inner surface of the convex surface portion of the transparent cover is prevented from going outward from the region of the convex surface portion in the thickness of the transparent cover.
[0009]
The convex surface may be a spherical surface or an aspherical curved surface, and the transparent cover may be formed thinner at the outer edge portion of the convex surface portion than the periphery thereof.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments 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 portion flexible tube of an endoscope, and an observation window 3 and an illumination window 4 are arranged side by side on the distal end surface of a distal end portion main body 2 connected to the distal end. Yes. A concave lens is fitted in the illumination window 4.
[0011]
An objective optical system 5 is disposed inside the observation window 3, and an image incident surface (or an imaging surface of a solid-state image sensor) of the image guide fiber bundle 6 is disposed at a subject projection position by the objective optical system 5. An exit end of the light guide fiber bundle 7 is disposed inside the illumination window 4.
[0012]
Reference numeral 10 denotes a covering sheath that is detachably covered with the insertion portion flexible tube 1, and the tip portion thereof is made of a transparent plastic such as polypropylene or polyethylene that covers the tip surface of the tip portion main body 2. A 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 surface portion. 12 is formed in a spherical shape.
[0014]
As a result, of the illumination light emitted from the illumination window 4, the light reflected by the inner surface of the convex surface portion 12 of the transparent cover 11 and returned into the convex surface portion 12 of the transparent cover 11 is within the thickness of the transparent cover 11. It does not go outward from the region of the convex surface portion 12.
[0015]
Note that, as indicated by A in the figure, the light reflected outward at the position near the center of the convex surface portion 12 is repeatedly reflected in the convex surface portion 12 and approaches the outer edge of the convex surface portion 12. The reflection direction changes inward.
[0016]
In order to theoretically and completely eliminate light leakage outside the region of the convex surface portion 12, it is necessary to make the radius of curvature of the convex surface portion 12 smaller than a certain value, but the value is emitted from the light guide fiber bundle 7 Since it differs depending on the maximum emission angle of the illumination light to be emitted, the radius of curvature of the concave lens disposed in the illumination window 4, the refractive index of the material forming the transparent cover 11, etc., the radius of curvature of the convex surface portion 12 taking these into account Should be set.
[0017]
In the distal end portion of the endoscope of the embodiment configured in this way, the illumination light emitted from the illumination window 4 is reflected by the inner surface of the convex surface portion 12 of the transparent cover 11 and returned into the transparent cover 11. Since light does not finally go outward from the region of the convex surface portion 12 in any direction, there is almost no occurrence of flare due to internal reflection in the transparent cover 11, and good observation with good contrast through the observation window 3. An image can be obtained.
[0018]
The present invention is not limited to the above embodiment. For example, the convex surface portion 12 does not necessarily have a spherical surface, and an elliptical surface or other aspherical curved surface (for example, a paraboloid surface) as shown in FIG. Etc.).
[0019]
Further, as shown in FIG. 3, by forming the transparent cover 11 thinner at the outer edge portion of the convex portion 12 than the periphery thereof, light leakage from the region of the convex portion 12 to the outside thereof can be cut also at that portion. Can contribute to flare reduction.
[0020]
【The invention's effect】
According to the present invention, the surface of the portion of the transparent cover that covers the illumination window is formed in a convex shape, and the light reflected from the inner surface of the convex portion of the transparent cover out of the illumination light emitted from the illumination window is transparent. By avoiding the convex area from going outside in the thickness of the surface, 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 body 3 observation window 4 illumination window 5 objective optical system 10 covering sheath 11 transparent cover 12 convex surface

Claims (2)

An illumination window for emitting illumination light and an observation window for taking a light image into the objective optical system are arranged side by side at the tip of the insertion portion, and the surface of the illumination window and the surface of the observation window are 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 into a spherical or aspherical convex curved surface, and is reflected by the inner surface of the curved portion of the transparent cover out of the illumination light emitted from the illumination window. The distal end portion of the endoscope, wherein the light does not go outside from the curved surface region within the thickness of the transparent cover. The transparent cover, the distal end portion of an endoscope according to claim 1 Symbol mounting is formed thinner than the region of the curved outer at the outer edge portion of the curved portion.

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