JPH0355941Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a rigid endoscope in which the outer diameter of an objective lens system is larger than the outer diameter of a gradient index relay lens.

[Technical background of the invention and its problems] In recent years, an elongated insertion section is inserted into a body cavity, etc., and an objective optical system formed at the distal end of the insertion section is used to image a target area such as an organ inside the body cavity. However, endoscopes that allow observation at the proximal eyepiece outside the body cavity via an image transmission means are now widely used for observation, diagnosis, and the like.

The above-mentioned endoscopes have a flexible insertion section and can be used to observe the target area in the body cavity through a curved path from the oral cavity, etc., and the other has a rigid insertion section and is inserted in a substantially straight line. There is a rigid endoscope that can be used.

Although the above-mentioned rigid endoscope cannot be inserted into a bent area, the image transmission means uses a relay lens system, etc., which provides a clearer image than the bendable image guide fiber bundle used in flexible endoscopes. It has the advantage of being obtained.

Even in the rigid endoscope using a relay lens system as the image transmission means, it is desirable that the outer diameter of the insertion portion be as small as possible. For this reason, Jikko 49-
As in the conventional example disclosed in Japanese Patent No. 23882, a conventional example is disclosed in which a refractive index gradient type relay lens (so-called self-occurring lens) is inserted into a hollow needle-like member (tubular member). In this conventional example, the diameter of the insertion part can be made sufficiently small, but since the above-mentioned self-occurring lens also serves as an objective lens system, it is not possible to use a general objective lens system that allows the observation range that can be imaged to be designed with a wide degree of freedom. The drawback was that it was narrow compared to the previous one. Furthermore, it is difficult to obtain a wide field of view, and in order to obtain a wide field of view, different self-cleaning lenses must be prepared as a whole, which increases manufacturing costs. Furthermore, while the above-mentioned self-cleansing lenses have a very small diameter, due to the process of manufacturing with distributed refractive index, the outer diameter of the manufactured elongated self-cleansing lenses may vary slightly or be slightly curved. Therefore, it is necessary to provide a gap in the tubular member through which the self-cleaning lens is inserted, but if the front end of the self-cleaning lens is not installed eccentrically, it may cause vignetting or flare of the light beam. This has the disadvantage that the degree of freedom in lens design is reduced.

Furthermore, in the conventional example disclosed in JP-A No. 58-184113, the objective lens has an outer diameter equal to that of the self-occurring lens for image transmission, and the objective lens must be processed with high precision. In addition, the adhesive layer between the outer periphery of the objective lens and the lens tube becomes thicker, which causes the adhesive to deteriorate during disinfection with a chemical solution, resulting in water leakage.
Furthermore, the objective lens has the disadvantage that the effective diameter is small because the gap is not effectively utilized.

[Purpose of the invention] The present invention was made in view of these circumstances, and it is possible to reduce the variation in the outer diameter and curvature of the refractive index gradient type relay lens disposed in the lens tube between the inner periphery of the lens tube and the outer periphery of the relay lens. On the other hand, even if a space is provided between the outer periphery of the gradient index relay lens and the inner periphery between the lenses, the objective lens system can be absorbed without decentering the objective lens system toward the tip of the lens tube. It can be easily installed, and as a result, it is possible to prevent variations in the viewing range from product to product. Furthermore, by joining the rear end of the objective lens diameter and the tip of the refractive index gradient type relay lens, light is The object of the present invention is to provide a rigid endoscope that eliminates reflections and can obtain bright and clear observation images.

[Means for Solving the Problems] In order to achieve the above object, the rigid endoscope according to the present invention includes an objective lens for imaging consisting of a single or a plurality of lenses in a lens tube inserted into the insertion section. a rigid endoscope in which a refractive index gradient type relay lens for image transmission is disposed, at least a single lens constituting an objective lens system disposed in front of the refractive index gradient type relay lens; is larger than the outer diameter of the gradient index relay lens and has an outer diameter that fits into the inner periphery of the lens tube, and forms a space between the outer periphery of the gradient index relay lens and the inner periphery of the lens tube. Furthermore, the tip of a gradient index relay lens is joined to the rear end of the objective lens system.

[Embodiments of the invention] The invention will be specifically described below with reference to the drawings.

Figures 1 to 3 relate to the first embodiment of the present invention, with Figure 1 showing the overall structure of the first embodiment, Figure 2 showing the front end of the insertion part, and Figure 3 showing the front end of the insertion part. The distal end side is shown in an enlarged cross-sectional view.

The direct-viewing rigid endoscope 1 of the first embodiment includes an elongated first insertion section 2A that can be inserted into a body cavity, and a second insertion section 2B that has a larger diameter than the insertion section 2A.
and a larger-diameter operating section 3 connected to the rear end.
and an eyepiece section 4 formed on the rear end side of the operating section 3.

The first insertion portion 2A is covered with a first outer tube 5A having a rigid and small diameter pipe shape, and the rear end of this outer tube 5A is connected to a second outer tube 5 having a large diameter via a flange 6.
The rear end of the outer tube 5B is fixed by brazing or the like to the inner peripheral surface of the open front end of the operating section 3, which has a light guide cap 7 on the side to which a light guide cable (not shown) is attached. ing.

A connecting member 10 whose front end side outer circumferential surface fits into the rear end inner circumferential surface is connected to the rear end side of the operating section main body 9 forming the operating section 3 by adhesive or brazing. A watertight O-ring 11 is housed in a recess formed on the outer periphery of the eyepiece, and the outer periphery forming the recess is covered with the first eyepiece cover 12A so that the inner periphery on the front end side thereof is fitted. There is.

The first eyepiece cover 12A has a substantially cylindrical shape, and a recess is formed on the outer periphery of the substantially central part to accommodate a watertight O-ring 13, and a male thread is formed on the outer periphery of the rear end, and the recess is formed in the outer periphery of the first eyepiece cover 12A. A second eyepiece cover 12B is attached, whose front inner circumference fits into the outer circumference, and whose rear inner circumference has a female thread that is screwed into the male thread. The second eyepiece cover 12B has an eyepiece frame 14 whose diameter increases rearwardly fitted and fixed on the outer periphery of the rear end, and a cover glass 15 is attached to the inner periphery of the rear end of the second eyepiece cover 12B.

By the way, in the first outer tube 5A forming the insertion portion 2A, there is a first lens tube 1 as an optical system storage tube in contact with, for example, the upper inner peripheral surface of the outer tube 5A.
6A is inserted through the lens tube 16A, and the lens tube 16A is inserted into the second lens tube 16A.
The outer periphery of the rear end of the connecting member 17 is fitted and fixed to a connecting member 17 that is fitted and fixed in the outer tube 5B, and the rear end of the connecting member 17 is fitted and fixed to an inner tube 19 having a diameter larger than that of the first lens tube 16A. has been done. A second lens tube 16B is inserted into the inner tube 19 so as to fit therein, and the rear end of the inner tube 19 is attached to the inner periphery of the front end of the connecting member 10 in the operation section 3 with adhesive or brazing. It is fitted and fixed.

The remainder of the first outer tube 5A, through which the first lens tube 16A is inserted, has a generally crescent-shaped portion (in cross section) (see FIG. 2) that has a small diameter fiber bundle (optical A light guide 20 formed of a fiber bundle (fiber bundle) is inserted, and this light guide 20 is further inserted into the second outer tube 5B, and then bent inside the operating section main body 9, and the rear end is bent by the light guide base 7. is fixed.

Lens tube 1 inserted into the first outer tube 5A
6A fits most of its inner diameter of 1.1mm for example
A concave lens 21, a rod lens 22, and a convex lens 23 having an outer diameter of 1.1 mm are joined together, and their outer peripheries are bonded to the inner wall of the lens tube 16A, thereby closing the front end. At the back, a double lens 24 and a rod lens 25 of almost 1.1 mm, which fit into the inner diameter of the lens tube 16A, are bonded to each other, and their outer peripheries are attached to the inner wall of the lens tube 16A with a small amount of adhesive so that they do not wobble. The concave lens 21, the rod lens 22, and the convex lens 2 are fitted and fixed.
3 forms an objective lens system 26. Its end surface is connected to the rear end surface of the innermost rod lens 25 forming this objective lens system 26, and the relay lens A narrow-diameter refractive index gradient type relay lens (so-called self-occurring lens) 27 forming the system is connected to the lens tube 16.
It is inserted through A. This self-cleaning lens 27 has an outer diameter slightly smaller (for example, 1 mm) than the inner diameter of the lens tube 16A, and the outer diameter of the self-cleaning lens 27 may vary slightly or be slightly curved. It is now possible to insert it even if it is inserted.

In the lens tube 16A in which the objective lens system 26 and the self-occurring lens 27 for image transmission are housed, the objective lens system 26 has an outer diameter that fits into the inner periphery of the self-occurring lens 27, which is slightly larger than the outer diameter of the self-occurring lens 27. Possibly, the objective lens system 26
The objective lens system 26 can be easily installed in the lens tube 16A without being decentered by simply applying a small amount of adhesive to the outer periphery of the lens and dropping it into the lens tube 16A. Further, since the effective diameter of the objective lens system 26 is utilized to the maximum (without creating a gap), a bright and clear image can be formed.

The image formed by the objective lens system 26 is transmitted to the rear of the insertion section 2A by a self-occurring lens 27 located behind it.

At the rear end of the self-cleaning lens 27, near the front end of the inner tube 19, there is a center cover glass which has a diameter larger than the outer diameter of the self-cleaning lens 27, fits into the inner periphery of the inner tube 19, and has a thick wall. They are closely attached so that the axis and optical axis are aligned. After being transmitted through this self-cleaning lens 27, spaced rings 28 and 2 are placed in the second lens tube 16B, which has a large diameter.
The signal is transmitted through a second relay lens system formed of, for example, double lenses 31 and 32 held at appropriate intervals by lenses 9 and 30, and transmitted by a field lens 33.
The image is formed at a position in front of the field stop 39 behind the field lens 33.

The double lens 31 on the front end side of the second lens tube 16B is fixed, for example, by a press-fitted lens holding fitting 34, and an aperture stop 35 is provided in the middle of the lenses 31, 32.

The rear end of the second lens tube 16B, which can be fitted into the inner tube 19 and has a relay lens system arranged inside, has an outer diameter that fits into the inner circumference of the connecting member 10 in the operating section 3. The eyepiece frame 37 is fitted and fixed to the inner periphery of the front end of an eyepiece frame 37, which has a male thread 36 that is screwed into a female thread formed on the inner periphery of the rear end of the connecting member 10.

A field lens 33 is disposed within the eyepiece frame 37 via a lens frame 38, a field stop 39 is formed behind the field lens 33, and an eyepiece 40 is disposed behind it. The eyepiece lens 40 is fixed by an annular retaining nut 41 so as to be pressed forward.
The distance between the eyepiece lens 40 disposed within the eyepiece lens frame 37 and the front surface (image position) of the field stop 39 is set to an appropriate distance.

Further, the field lens 33 does not touch the eyepiece frame 14 when the front end 42 of the convex portion, which is the rear end of the second eyepiece cover 12B protruding radially inward, is brought into contact with the rear end surface of the eyepiece frame 37. When observing the image closely, the observation position is set to be the eye point where the image can be observed most easily, when the image is observed neither too close nor too far away.

Further, the relay lens system in the second lens tube 16B whose rear end is fixed to the eyepiece frame 37 uses lenses 31 and 32 with an outer diameter larger than that of the first lens tube 16A and easier to process. , pass through the field lens 33 by using spacing rings 28, 29, and 30 of a predetermined length, and the field aperture 39.
The image is transmitted to the front end.

The eyepiece frame 37, which is connected to the second lens tube 16B through which the relay lens system is inserted and has an eyepiece system such as the eyepiece 40 attached thereto, is a portion that is screwed into the connecting member 10 to which the inner tube 19 is fixed. By changing the length, it is possible to adjust the movement back and forth. Therefore, the self-cleaning lens 2 inserted into the first lens tube 16A having a small diameter
Even if there is a shift in the image transmission position due to manufacturing variations, etc., the connecting member 10
The second lens tube 16B is moved together with the eyepiece system into the inner tube 19 whose rear end is fixed, and the amount of insertion into the inner tube 19 can be adjusted by rotational operation, and the appropriate amount after adjustment can be adjusted. At the set position, the eyepiece frame 37 can be fixed with a presser screw 43 that is screwed into the screw hole of the connecting member 10.

According to the first embodiment configured in this way, the objective lens system 26 and the self-cleaning lens 27 are inserted into the first insertion section 2A inserted into the body cavity.
Each lens group 2 forming the objective lens system 26 is disposed inside the first lens tube 16A.
2, 23, 24, and 25 have outer diameters that fit into the inner diameter of the lens tube 16A, so when assembling the observation optical system, the objective lens system 26 can be attached by simply dropping it into the lens tube 16A. Even simple work can be done in a short time without causing eccentricity or wobbling of the objective lens system 26.

Further, by simply changing the focal length of the objective lens system 26, different viewing ranges can be realized.

In addition, since the effective diameter of the objective lens system 26 is utilized to the maximum, a bright image can be obtained, and
It can form high-resolution images, making it possible to observe clear images.

FIG. 4 shows the distal end side of the insertion section of a direct-viewing rigid endoscope according to a second embodiment of the present invention.

As shown in the figure, in this embodiment, the front end of the first lens tube 16A is closed with a disk-shaped cover glass 51 having an outer diameter that fits into the inner periphery of the lens tube 16A. Into the first lens tube 16A, a rod lens (gradient refractive index mini-lens) 52 is fitted and fixed, the front end of which is in contact with or joined to the rear end of the cover glass 51 to form an objective lens. The self-cleaning lens 27 is placed so that its front end surface is in contact with the rear end surface of the rod lens 52.
is installed.

The outer diameter of the rod lens 52 as the objective lens is almost equal to the inner diameter of the first lens tube 16A, and the rod lens 52, which serves as the objective lens, is almost equal to the inner diameter of the first lens tube 16A. , it can be easily installed as in the first embodiment. The rest of the structure is the same as that of the first embodiment.

This second embodiment has the same effects as the first embodiment, but since the objective lens is formed of a single piece, it has the advantage that the assembly work can be made easier.

Note that the lens tube 16A is not limited to being inserted eccentrically into the outer tube 5A; for example, as shown in FIG. The light guide 20 may be inserted through the outer periphery so as to be inserted along the axis.

For example, in FIG. 5, the rod lens 52
The front end surface side is covered with a cover glass 5 with a large refractive index.
Even if the light incident through 1 has a large incident angle with the optical axis, it can be taken in without being reflected by the contacting surface or the bonding surface.
Further, the rear end surface side is made to have a refractive index approximately equal to or smaller than the refractive index of the front end surface portion of the self-occurring lens 27 bonded to the rear end surface, so that light can be effectively transmitted to the self-occurring lens 27 side. It can also be done.

In addition, among the single or plural lenses forming the objective lens system, all of them are not limited to those having an outer diameter that fits into the inner periphery of the lens tube 16A, and at least the single or plural lenses on the front end side are not limited to those having an outer diameter that fits into the inner periphery of the lens tube 16A. Those with an outer diameter that fits within the scope of the present invention belong to the present invention. This is, for example, the objective lens system 26 shown in FIG.
In the case where the rearmost rod lens 25 is made equal to the outer diameter of the self-cleaning lens 27, and the rear end surface is joined to the front end surface of the self-cleaning lens 27 (joined so that no step is formed on the outer periphery), the above-mentioned This is because it can be made to have the following advantages.

In addition, if the cover glass attached to the front end of the lens tube 16A has a part of the function of an objective lens system, the objective lens system includes the cover glass, and in this case, However, the present invention also includes a lens (group) forming the remaining objective lens system whose outer diameter is smaller than the outer diameter that fits into the lens tube 16A.

Note that the present invention is not limited to the rigid endoscope 1 having the structure shown in FIG.
This can be applied to a relay lens system that transmits the image formed by the objective lens, and a self-occurring lens is used at least in the rear part adjacent to the objective lens, and the insertion part is a single one. Of course, it can also be applied to diameters. Moreover, it is applicable not only to the direct view type but also to the oblique view type and the side view type.

It is clear that the present invention is applicable not only to a single self-cleansing lens but also to a plurality of self-cleansing lenses. Also, in this case,
For short self-occurring lenses, one with an outer diameter that almost fits into the lens tube can be used.

[Effects of the invention] As explained above, according to the present invention, variations in the outer diameter and curvature of the refractive index gradient relay lens disposed in the lens tube can be reduced by reducing the space between the inner circumference of the lens tube and the outer circumference of the relay lens. On the other hand, even if a space is provided between the outer periphery of the gradient index relay lens and the inner periphery of the lens tube, it is not possible to easily mount the objective lens system on the tip side of the lens tube without decentering it. As a result, variations in the field of view between products can be prevented, and the rear end of the objective lens diameter and the tip of the refractive index gradient type relay lens are bonded to eliminate light reflection due to an intervening air layer, making it brighter. This has the effect of making it possible to obtain a clear observation image.

[Brief explanation of the drawing]

1 to 3 relate to the first embodiment of the present invention, FIG. 1 is a sectional view showing the overall structure of the rigid endoscope of the first embodiment, and FIG. 2 is a front end surface of the insertion section. FIG. 3 is an enlarged sectional view showing the vicinity of the objective lens system on the distal end side of the insertion section in FIG. FIG. 5 is a cross-sectional view showing a modification of FIG. 4. 1... Rigid endoscope, 2A, 2B... Insertion section, 3
...Operation unit, 4...Eyepiece, 5A...First outer tube, 5B...Second outer tube, 9...Operation unit main body, 1
0... Connecting member, 12A... First eyepiece cover,
12B...second eyepiece cover, 16A...first lens tube, 16B...second lens tube, 19...
Inner tube, 20...Light guide, 21...Cover glass, 22, 25...Rod lens, 26...Objective lens system, 27...Refractive index gradient type relay lens (self-occurring lens), 31, 32...2 Heavy lens, 33...field lens, 35...brightness aperture, 37...eyepiece frame, 39...field diaphragm, 40...eyepiece, 51...cover glass, 52...rod lens.

Claims (1)

[Scope of utility model registration request] In a rigid endoscope, an objective lens system for imaging consisting of one or more lenses and a gradient index relay lens for image transmission are disposed in a lens tube inserted into an insertion section, At least one lens constituting an objective lens system disposed in front of the gradient index relay lens has an outer diameter larger than the outer diameter of the gradient index relay lens and fits into the inner periphery of the lens tube. A space is formed between the outer periphery of the gradient index relay lens and the inner periphery of the lens tube, and the tip of the gradient index relay lens is joined to the rear end of the objective lens system. Rigid endoscope.