JP2004041458A - Endoscope tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distal end of an endoscope which can obtain better observation images with neither flare nor ghost in the distal end of the endoscope in which the surfaces of the lighting window and the observation window are covered with the same cover. <P>SOLUTION: In the distal end of the endoscope in which the lighting window 4 emitting illumination lights and the observation window 3 for taking the optical images thereinto are arranged side by side at the tip parts of the insertion tubes 1 and 2 and the surfaces of the lighting window 4 and the observation window 3 are covered with the same transparent cover 11, the external surface of the portion covered with the lighting window 4 of the transparent cover 11 is formed into a concave surface 12 of a concave lens shape. <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 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 with 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, the illumination light emitted from the illumination window 101 repeats reflection within the thickness of the transparent cover 102 as shown in FIG. 2, for example. The light enters the observation window 103, and flares and ghosts occur in the observation visual field.
[0005]
Therefore, conventionally, the thickness of the transparent cover is gradually increased, 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 increases. In such a case, the incidence of light on the observation window becomes larger than the maximum incident angle of the observation optical system, thereby suppressing the occurrence of flare and ghost (Japanese Patent No. 2868228).
[0006]
[Problems to be solved by the invention]
However, even if measures such as gradually increasing the thickness of the transparent cover from the illumination window side to the observation window side are taken, of the illumination light emitted from the illumination window, the light directed in a direction other than the observation window is reflected at the periphery and the like. Then, when the light reaches the observation window, it may be incident on the observation window at an incident angle smaller than the maximum incident angle of the objective optical system, and flare or ghost may occur in the observation visual field.
[0007]
Therefore, the present invention provides a tip of an endoscope that can obtain a good observation image without flare or ghost at the tip 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 a department.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the distal end portion of the endoscope of the present invention is arranged such that an illumination window for emitting illumination light and an observation window for taking in a light image are arranged side by side at the distal end of the insertion portion, and the surface of the illumination window At the distal end of the endoscope whose surface is covered with the same transparent cover, the outer surface of the transparent cover covered with the illumination window is formed as a concave lens-shaped concave surface.
[0009]
In addition, the diameter of the outer edge of the concave surface may be formed to be larger than that of the illumination window to such an extent that all the illumination light emitted from the illumination window hits the concave surface.
[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, which emits an observation window 3 for taking in a light image and illumination light to a distal end surface of a distal end main body 2 connected to the distal end. The illumination windows 4 are arranged side by side.
[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 face of the light guide fiber bundle 7 is arranged in the illumination window 4.
[0012]
Reference numeral 10 denotes a covering sheath which is detachably covered on the insertion portion flexible tube 1, and has a transparent portion made of a transparent plastic such as polypropylene or polyethylene which covers the distal end surface of the distal end body 2 at its distal end portion. The cover 11 is attached, and the observation window 3 and the illumination window 4 are in a state of being tightly covered with the same transparent cover 11, respectively.
[0013]
Such a transparent cover 11 is formed to have a constant thickness as a whole, but a concave lens-shaped concave surface 12 is formed on the outer surface of a portion covering the illumination window 4, and the light guide fiber bundle 7 The diameter of the outer edge of the concave surface 12 is formed to be larger than the emission end surface of the light guide fiber bundle 7 (i.e., the illumination window 4) to some extent so that all the emitted illumination light hits the concave surface 12.
[0014]
At the distal end portion of the endoscope of the embodiment configured as described above, the illumination light emitted from the illumination window 4 passes through the transparent cover 11, and most of the illumination light passes through the concave surface 12 and irradiates the subject. As shown by A in FIG. 1, a part of the light is reflected by the concave surface 12 and returned to the thickness of the transparent cover 11.
[0015]
However, when light is reflected within the thickness of the transparent cover 11 at the point A, the reflection angle is larger than that in the case of the parallel plane plate, because the light is not the parallel plane plate but the concave surface 12.
[0016]
As a result, even if the light is repeatedly reflected within the thickness of the transparent cover 11 and enters the observation window 3, the probability that the angle of incidence becomes larger than the maximum angle of incidence of the objective optical system 5 increases, and flare and ghosts are reduced. Generation is suppressed.
[0017]
Further, of the illumination light emitted from the illumination window 4 and repeatedly reflected within the thickness of the transparent cover 11, the illumination light does not directly go to the observation window 3 but once goes to a direction other than the observation window 3, and then goes around the transparent cover 11. Some light is reflected toward the observation window 3 after being reflected by the light source or the like, and all of the light has a large reflection angle due to reflection on the concave surface 12.
[0018]
Therefore, there is a high probability that the light incident on the observation window 3 from any direction through the thickness of the transparent cover 11 has an incident angle larger than the maximum incident angle of the objective optical system 5, and the occurrence of flare and ghost is suppressed. Is done.
[0019]
In this way, the occurrence of flare or ghost due to internal reflection on the transparent cover 11 is almost completely eliminated, and a good observation image with good contrast can be obtained through the observation window 3.
[0020]
【The invention's effect】
According to the present invention, since the outer surface of the portion of the transparent cover covered with the illumination window is formed as a concave lens-shaped concave surface, reflection from the illumination window is repeated within the thickness of the transparent cover after being emitted from the illumination window. The light reaching the observation window has a large reflection angle when reflected from the illumination window in any direction at the time of reflection on the concave surface.Therefore, the incidence angle to the observation window is likely to be larger than the maximum incidence angle of the objective optical system. And a good observation image without ghost 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 an embodiment of the present invention.
FIG. 2 is a side sectional view of a distal end portion of a conventional endoscope.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insertion part flexible tube 2 Tip part main body 3 Observation window 4 Illumination window 5 Objective optical system 10 Coating sheath 11 Transparent cover 12 Concave surface

Claims (2)

An illumination window for emitting illumination light and an observation window for taking in a light image are arranged side by side at the tip of the insertion section, and the surface of the illumination window and the surface of the observation window are covered with the same transparent cover. At the tip
A distal end portion of an endoscope, wherein an outer surface of a portion of the transparent cover covered with the illumination window is formed as a concave surface of a concave lens shape. The distal end portion of an endoscope according to claim 1, wherein a diameter of an outer edge of the concave surface is formed larger than that of the illumination window to such an extent that all illumination light emitted from the illumination window hits the concave surface.

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