JP4297481B2 - 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 between patients via an endoscope.
[0003]
As a countermeasure, a watertight outer sheath that can be removed from the insertion portion of the endoscope is provided, and the endoscope is used with the outer sheath covered, and the outer sheath is replaced with a new one after use. One powerful tool is to do. In such a case, the outer sheath portion 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 single transparent cover, for example, as shown in FIG. 3, the component reflected by the inner surface of the transparent cover 102 of the illumination light emitted from the illumination window 101 is reflected. In some cases, reflection is repeated within the thickness of the transparent cover 102 and enters the observation window 103, and ghost or flare may occur in the observation field.
[0005]
Therefore, conventionally, the light emitted from the illumination window is reflected in the direction toward the observation window within the thickness of the transparent cover, for example, by gradually reducing the thickness of the front end surface of the transparent cover from the illumination window side to the observation window side. When it is repeated, the reflection angle is gradually reduced so as not to reach the observation window (for example, Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent No. 2868228 [0007]
[Problems to be solved by the invention]
However, since such a transparent cover is generally manufactured by plastic molding, if the thickness of the front end surface is gradually changed, the thickness change in the middle portion becomes uneven due to so-called “sinking” at the time of molding. In some cases, the endoscopic observation image is distorted or damaged due to insufficient strength of the portion on the observation window side where the thickness is reduced.
[0008]
Therefore, the present invention provides a good observation image free from ghosts and flares by using a transparent cover having a uniform thickness 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. It is an object to provide a distal end portion of an endoscope capable of obtaining the above.
[0009]
[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 thickness of at least the portion of the transparent cover that covers the surface of the illumination window and the surface of the observation window is uniform. In addition, a portion through which illumination light emitted from the illumination window passes is formed in a shape bulging outward.
[0010]
In addition, the part bulging outward of the transparent cover may be formed in a substantially spherical shape.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows the distal end portion of the endoscope according to the first embodiment of the present invention, and 2 is a distal end portion main body connected to the distal end of the flexible insertion portion of the endoscope. An observation window 3 for taking in an optical image and an illumination window 4 for emitting illumination light are arranged side by side on the distal end surface of the distal end body 2, and a concave lens is fitted in the illumination window 4. .
[0012]
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.
[0013]
11 is a hard and transparent material such as an acrylic resin or a polycarbonate resin provided so as to cover the distal end surface of the distal end portion body 2 at the distal end of the covering sheath that is detachably coated on the insertion portion flexible tube 1. A transparent cover made of plastic.
[0014]
Of each part of the transparent cover 11, at least a part covering the surface of the observation window 3 and the surface of the illumination window 4 is formed to have a uniform thickness, and a part through which illumination light emitted from the illumination window 4 passes. Is formed in a substantially spherical shape bulging outward (bulging portion 12).
[0015]
In addition, since the transparent cover 11 has a uniform thickness in the bulging portion 12, the transparent cover 11 does not have a lens action, and thus there is no inconvenience such as narrowing the light distribution angle of illumination light.
[0016]
In this embodiment, the center position O of the curvature (radius R) of the bulging portion 12 is provided so as to coincide with the convergence position (virtual point) of the illumination light emitted radially from the light guide fiber bundle 7 toward the subject. It shows the case of special conditions.
[0017]
Under such conditions, the bulging portion of the transparent cover 11 out of the illumination light A emitted at the largest angle in the direction closer to the observation window 3 from the end portion S closest to the observation window 3 of the light guide fiber bundle 7. The component reflected by the inner surface of 12 is returned toward the end S that is the starting point, and does not proceed toward the observation window 3 within the thickness of the transparent cover 11.
[0018]
In addition, the component reflected by the inner surface of the bulging portion 12 of the transparent cover 11 in the illumination light B emitted from the position farther from the observation window 3 in the emission end face of the light guide fiber bundle 7 The reflection is repeated in the thickness and the direction toward the observation window 3 is approached.
[0019]
However, since the reflection angle is extremely small due to the relationship with the direction of the surface of the bulging portion 12, the number of reflections within the thickness of the transparent cover 11 is very large. As a result, the light attenuates within the transparent cover 11. Thus, the observation window 3 is not substantially reached.
[0020]
Accordingly, there is almost no ghost or flare due to reflection within the thickness of the transparent cover 11, and a good observation image with good contrast can be obtained through the observation window 3.
[0021]
FIG. 1 shows a second embodiment of the present invention, in which the center position O of the curvature (radius R) of the bulging portion 12 of the transparent cover 11 is emitted radially from the light guide fiber bundle 7 toward the subject. It is located behind the convergence position (virtual point) of the illumination light. The rest is the same as the first embodiment described above.
[0022]
In this embodiment, the illumination light C emitted from the end S closest to the observation window 3 of the light guide fiber bundle 7 and the emission end face of the light guide fiber bundle 7 are emitted from a position farther from the observation window 3. The reflected component of the illumination light D on the inner surface of the bulging portion 12 of each transparent cover 11 is reflected in the direction closer to the observation window 3 than in the direction returning to the end portion S that is the starting point.
[0023]
The reflection angle is larger than that in the case of the first embodiment of FIG. 2, but the transparent cover 11 covers the surface of the illumination window 4 parallel to the orientation of the surface of the bulging portion 12. Compared to cases, the angle is extremely small.
[0024]
Therefore, the number of reflections within the thickness of the transparent cover 11 of the light reflected in the direction of the observation window 3 in the thickness of the transparent cover 11 is very large. As a result, the light is attenuated in the transparent cover 11. As a result, the observation window 3 is hardly reached.
[0025]
Accordingly, there is almost no ghost or flare due to reflection within the thickness of the transparent cover 11, and a good observation image with good contrast can be obtained through the observation window 3.
[0026]
【The invention's effect】
According to the present invention, among the respective parts of the transparent cover, at least the portion covering the surface of the illumination window and the surface of the observation window is uniformly formed, and the portion through which the illumination light emitted from the illumination window passes is outward. Since the number of reflections within the thickness of the transparent cover within the thickness of the transparent cover is very large, the light is reflected in the thickness of the transparent cover. Attenuates within the transparent cover and hardly reaches the observation window. As a result, even if the surface of the illumination window and the surface of the observation window are covered with a uniform transparent cover, there is no ghost or flare. Can be obtained.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a distal end portion of an endoscope according to a second embodiment of the present invention.
FIG. 2 is a side sectional view of the distal end portion of the endoscope according to the first embodiment of the present invention.
FIG. 3 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 11 transparent cover 12 bulge portion O center position of curvature of the bulge portion

Claims (3)

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 made of a hard plastic material. At the tip of the endoscope covered with a transparent cover,
Of each part of the transparent cover, at least the thickness of the portion covering the surface of the illumination window and the surface of the observation window is uniformly formed, and the portion covering the surface of the observation window is along the surface of the observation window. A distal end portion of an endoscope which is formed in a flat shape and only a portion through which illumination light emitted from the illumination window passes is formed in a spherical shape and bulges outward. An exit end of the light guide fiber bundle is disposed inside the illumination window, and the center position of the curvature of the spherical portion of the transparent cover that swells in a spherical shape extends forward from the light guide fiber bundle. The distal end portion of the endoscope according to claim 1, which coincides with a virtual converging position of light . An exit end of the light guide fiber bundle is disposed inside the illumination window, and the center position of the curvature of the spherical portion of the transparent cover that swells in a spherical shape extends forward from the light guide fiber bundle. The distal end portion of the endoscope according to claim 1, wherein the distal end portion is located behind the virtual light converging position.

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