JPS6052816A - Endoscope - Google Patents

Abstract

PURPOSE:To illuminate more efficiently the inside wall surface of a tube by forming an endoscope in such a way that the illuminating light transmitting a lens is distributed darkly at the center and brightly annularly at the periphery to the central part at the exit end of an optical element for accepting the illuminating light from a light guide. CONSTITUTION:The illuminating light made incident from a light guide 3 to the inside of an optical element 5 repeats reflection on the circular conical surface 12 of a recess 10 and the outside circumferential surface 13 of the element 5 and thereafter the light is emitted annularly from an exit end 9 and is condensed by passing through a convex lens 7. The inside wall surface 14 of the tube and a visual field range X are thus concentrically illuminated in the case of illuminating said wall surface. The emphatic illumination is thus efficiently accomplished without wasteful irradiation of the illuminating light in the forward direction of the tube axis.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to an endoscope with an improved illumination optical system.

[Prior art]

Conventionally, various methods have been proposed for widening the illumination range in accordance with the widening of the viewing optical system in endoscopes. For example, it is disclosed in JP-A-54-89749, JP-A-47-41639, and Utility Model Publication JP-U-52-10346.

However, these means of widening the illumination range simply widen the illumination range, so when observing the inner wall surface of a tube such as a body cavity such as the esophagus or intestine, the observation direction is direct and relative to the tube axis. Problems still existed when providing rotationally symmetrical illumination. In this case, the light distribution of the illumination light is
As shown in the figure, the brightest area is near the center, and it gets darker towards the periphery. Since the inner wall surface of the tube to be observed is located at the periphery of the illumination range, it is very dark and the amount of light in the center of the illumination range does not contribute to observation and is wasted, resulting in extremely poor illumination efficiency.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide efficient illumination of the inner wall surface of the tube by intensively illuminating the inner wall surface of the tube, which is the field of view in the vicinity of the tip of the endoscope. Our goal is to provide endoscopes.

[Summary of the invention]

The present invention receives illumination light from a light guide.

In an endoscope, illumination light that is emitted from the output end and transmitted through a lens is distributed at the center of the output end of an optical element such that the center is dark and the periphery is bright in a ring shape.

[Embodiments of the invention]

Each embodiment of the present invention will be described below.

FIG. 2 shows a first embodiment of the invention. Reference numeral 1 in FIG. 2 is a distal end component in the insertion section of the endoscope, and an illumination light output optical system 2 is incorporated in this distal end component 1. This output optical system 2 is formed by optically connecting an optical element 5 (described later) to an output end 4 of a light guide 3 that guides illumination light, and further includes an illumination window 6 located in front of the optical element 5. A convex lens 7 is installed. The optical element 5 is made of a translucent material and is formed in the shape of a truncated cone, and its long diameter side end face is an input end 8, and the input end 8 is opposed to the output end 4 of the light guide 3. It is designed to be connected. Further, the shorter diameter side end face of the optical element 5 serves as an output end 9, and the output end 9 is installed facing the convex lens 7. Furthermore, a conical recess 10 is formed in the central portion of the output end 9 of the optical element 5. The shape of the depression 10 is such that when the illumination light emitted from the output end 9 passes through the convex lens 7, the light distribution characteristic on the assumed surface of the observation object is dark in the center and bright in a ring shape at the periphery, as shown in FIG. It is set to be. That is, light guide 3
The illumination light that enters into the optical element 5 is repeatedly reflected by the conical surface 12 of the recess 10 and the outer peripheral surface 13 of the optical element 5, and then exits from the output end 9 in a ring shape.

The light is then condensed by passing through the convex lens 7, resulting in a light distribution as shown in FIG.

The wall surface 14 is intensively illuminated, and illumination light is not wasted in front of the tube axis.

FIG. 5 shows a second embodiment. In this embodiment, the convex lens 7 in the first embodiment is replaced with a so-called ampan lens 15. That is, the ampan lens 15 has a peripheral cross-section having a convex lens cross-sectional shape, and has a shape obtained when it is rotated around the central axis of the optical element 5. However, this Anpan lens 15
Due to this action, the light emitted from the vicinity of the inner circumference of the output end 9 of the optical element 5 illuminates the outside of the ring-shaped illumination range 16, and the light emitted from the vicinity of the outer circumference of the output end 9 illuminates the inside of the illumination range 16. illuminate.

Therefore, in the light distribution, as shown in FIG. 6, the peak of the illumination light amount is closer to the inside of the illumination range 16 than in the first embodiment (see FIG. 3), and toward the outside of the illumination range 16. The amount of light decreases gradually. Therefore, when illuminating the inner wall surface 14 of the tube, as shown in FIG. 4, the maximum amount of light is emitted toward the farthest part, and the amount of emitted light decreases as it gets closer to the front, thus providing more uniform illumination as a whole. be able to.

FIG. 7 shows a third embodiment of the invention. In this embodiment, in order to widen the outer peripheral edge side of the output end 9 of the optical element 5 in the configuration of the first embodiment, the step 17 is expanded in the direction in which the outer diameter becomes larger.
It is integrally formed. By providing the step 17 having a larger diameter in this manner, the amount of light per unit area emitted from the vicinity of the outer periphery of the output end 9 is smaller than that emitted from the vicinity of the inner periphery. Therefore, the amount of illumination light outside the illumination range 16 is smaller than that inside.
The light distribution is as shown in FIG.

FIG. 9 shows a fourth embodiment of the invention. In this embodiment, in order to widen the inner peripheral edge side of the output @ 9 of the optical element 5 in the configuration of the second embodiment, the step 18 is expanded in the direction where the inner diameter becomes smaller.
It is integrally formed. Since the step 18 protruding toward the inner periphery is provided in this way, the amount of light per unit area emitted from the vicinity of the inner periphery of the output end 9 is smaller than that emitted from the vicinity of the outer periphery.

Therefore, compared to that of the second embodiment, the amount of illumination light changes more significantly from the inside to the outside of the illumination range 16.
As shown in Figure 0, the light distribution uniformly and gradually decreases.

FIG. 11 shows a fifth embodiment of the invention. In this embodiment, the convex lens 2 is replaced with the concave lens 19 in the configuration of the first embodiment.
It has been replaced with .

According to this configuration, the light ray 20 having the maximum intensity among the light rays emitted from the output end 9 of the optical element 5 is a light ray parallel to the optical axis, but this light ray 20 is bent toward the periphery by the concave lens 19. Therefore, the ring-shaped illumination is irradiated with a gentle light distribution as shown in FIG.

13 and 14 are for showing a sixth embodiment of the present invention. In FIG. , shows a state in a position conjugate to the assumed plane 11. 1st
In FIG. 4, the output end 9 of the optical element 5 is placed at a distance from its conjugate position by a distance expressed by the following equation.

Diameter (diameter) By configuring in this way, the shadow of dust placed on the output end face will not be clearly imaged on the assumed surface 11 (1?1≧
A/2tana).

Also, do not take the above value too large (1) 1≦3D/
2 tan α), ring-shaped illumination is possible.

Note that the present invention is not limited to the above embodiments, and may be modified as follows, for example.

The input and output ends of the optical element can be not only flat but also concave, convex, or aspherical. The surface of the lens can be aspherical as well as spherical. The outer periphery of the optical element can be not only tapered but also cylindrical or round. It may be shaped like an inverted barrel. In addition to being transparent, it may also be semi-transparent or reflective.

The depression can be not only conical but also spherical or pyramidal.
The inner peripheral surface of the recess may be not only linear but also concave or convex.

Further, the inner peripheral surface of the recess may be not only transparent but also translucent or reflective.

In the third and fourth embodiments, the level difference may be not only one level but a plurality of levels, and may be a gentle R-shaped level difference without a clear level difference.

It doesn't matter whether the output end of the light guide and the optical element are in contact with each other or not.

〔Effect of the invention〕

As explained above, the present invention forms a recess in the center of the output end of the optical element that receives illumination light from the light guide, and the light distribution of the illumination light that exits from the output end and passes through the lens is adjusted to the center. Since the area is dark and the surrounding area is bright in a ring shape, the viewing range such as the inner wall of the tube can be efficiently and focusedly illuminated.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the light distribution of irradiated light in a conventional endoscope, Fig. 2 is an explanatory diagram of the configuration of an output optical system showing the first embodiment of the present invention, and Fig. 3 is a diagram showing the irradiated light. FIG. 4 is a diagram showing a situation in which the inner wall surface of the tube is illuminated by the output optical system, and FIG. FIG. 6 is a diagram showing the light distribution by the output optical system, FIG. 7 is an explanatory diagram of the configuration of the output optical system according to the third embodiment of the present invention, and FIG. 8 is a diagram showing the light distribution by the output optical system. FIG. 9 is a diagram showing the fourth embodiment of the present invention.
FIG. 10 is a diagram showing the light distribution of the output optical system according to the fifth embodiment of the present invention, FIG. 11 is an explanatory diagram of the configuration of the output optical system according to the fifth embodiment of the present invention, 12th
The figure shows the light distribution by the output optical system, and FIGS. 13 and 13 are explanatory diagrams of the configuration of the output optical system for explaining the sixth embodiment of the present invention. 2... Output optical system, 3... Light guide, 5...
Optical element, 8...Incidence end, 9...Output end, 10...
- Hollow, 15...Anpan lens, 18...Step, 19...Concave lens, 20...Light ray. Applicant's representative Patent attorney Atsushi Tsuboi (Figure 4, Figure 8, Figure 9, Figure 10, Figure 12, Figure 13)

Claims (3)

[Claims] (1) A light guide that guides illumination light, an input end that is installed on the output end side of this light guide and receives illumination light from the output end of the light guide, and an output that outputs the illumination light received from this input end. an optical element made of a translucent material and having an end; a lens installed opposite to the output end of the optical element and transmitting illumination light emitted from the output end; What is claimed is: 1. An endoscope comprising: a recess formed in the center of the light emitting end so that the light distribution of illumination light transmitted through the lens is dark in the center and bright in a ring shape at the periphery. (2) The optical element is formed in the shape of a truncated cone, and the minor axis end face thereof is the output end.
The endoscope described in section. (3) The endoscope according to claim 2, wherein the recess is a conical hole.