JPH09127433A - Industrial endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope which prevents picture blur due to thermal expansion of a lens frame constituting the observation optical system of an endoscope in using the endoscope at a high temperature. SOLUTION: An observation optical system 60 is provided with a first lens frame 61 and a second lens frame 62. The first lens frame 61 is arranged for a front end constitution member 26a constituting a front end part 26 of an endoscope insertion part 21 and is an iron member having 11.8×10<-6> coefficient of linear expansion. The second lens frame 62 is arranged for the first lens frame 61 and is a brass member having 17.5×10<-6> coefficient of linear expansion. A cover glass 66 and a first piano-convex lens 67 are fixed to the inner peripheral surface on the front end side of the first lens frame 61 by adhesion, and a large-diameter part 68a of a base 68 to which an image guide 63 is inserted is fixed to the inner peripheral surface on the front end side of the second lens frame 62 by adhesion. The rear end face of a second piano-convex lens 69 is fixed to the front end face of this base 68 by adhesion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial endoscope in which the distance between lenses does not change due to thermal expansion when used at high temperatures.

[0002]

2. Description of the Related Art Conventionally, for example, when inspecting a turbine blade inside a jet engine of an aircraft, a fiberscope using an optical fiber or an endoscope insertion portion of an electronic endoscope using a CCD is inserted into the jet engine. Then, the turbine blades were inspected one by one.

Here, the structure of the distal end portion of a conventional industrial endoscope will be described with reference to FIG. As shown in the figure, the observation optical system 80 disposed in the distal end forming portion 81 that constitutes the distal end portion of the endoscope insertion portion includes a lens frame 82, a parallel plane cover glass 83, a first plano-convex lens 84, Second plano-convex lens 8
A plurality of lenses such as 5 and an image guide 86 facing the second plano-convex lens 85 are integrally incorporated.

That is, the lens frame 82 with the cover glass 83 and the first plano-convex lens 84 bonded together.
It is adhesively fixed to the tip side of. On the other hand, the second plano-convex lens 85 has a base 87 on the rear end surface of the plano-convex lens 85.
Is attached and fixed to the rear side of the lens frame 82 in a state in which the front end surface of the image guide 86 that has been inserted is fixed. A spacing tube 88 for setting a constant inter-lens distance L between the first plano-convex lens 84 and the second plano-convex lens 85 is arranged.

When inspecting the inside of the jet engine, there is a need to inspect as soon as possible after the flight. However, the temperature inside the jet engine is quite high immediately after the flight, so if you insert the endoscope into the jet engine at this point, the insertion part of the endoscope will be heated and the endoscope will be heated. The following problems occur.

(1) A plurality of optical systems made of glass, a lens frame made of metal or resin, an image fiber for transmitting an image, a light guide fiber for transmitting illumination light,
There is a risk that each bonded portion will be deformed or melted by heat.

(2) When the image fiber is covered with a metal base, the image fiber moves due to a large thermal expansion compared to the base due to the difference in thermal expansion coefficient between the image fiber and the base. As a result, the image fiber may be broken, or the end face of the image fiber may move, so that the image forming position may change and the image may be blurred.

(3) The plurality of optical systems made of glass, the lens frame or the interval tube made of metal or resin are thermally expanded, and the distance L between the lenses is changed, so that the focal length is changed and the image is displayed. There is a risk of blurring.

As a prior art for improving the problems of (1), (2), and (3), generally, the insertion portion is covered with a cylindrical heat-resistant member (heat-resistant jacket), and a liquid or gas is flown into the cylinder. It is known that it is cooled by cooling.

Further, in Japanese Patent Laid-Open No. 5-297286, there is provided a protective device for protecting the distal end portion of the endoscope insertion portion from thermal contact, and this protective device is provided with a radiation fin to enhance heat radiation. The prior art is shown in which the temperature rise at the tip of the endoscope is reduced to improve the problem (1).

Further, in Japanese Patent Laid-Open No. 3-216614, the metal protective tube is provided with a thermal expansion / contraction portion, while the image transmission fiber and the objective lens are made of quartz glass to improve the problem (2). Prior art is shown.

Further, in Japanese Patent Application Laid-Open No. 6-186466, it is not about the objective optical system provided in the endoscope but about the lens system of the camera for photography and the camera for television, but it is more than the linear expansion coefficient of the lens holding barrel. A prior art is shown in which a material having a large linear expansion coefficient of the main body holding the lens holding lens barrel is used to reduce the amount of change in the image forming position due to temperature change and to improve the inconvenience as described in (3) above. Has been done.

[0013]

However, the cylindrical heat-resistant member has a large outer diameter in order to cool a liquid or gas by flowing it into the cylinder, and is suitable for inspection when the inspection hole is relatively large. Not only is it applied, but a device for circulating a liquid or gas is required in addition to the endoscope.

Further, as in the above-mentioned Japanese Patent Laid-Open No. 5-297286, when a radiation fin is provided at the distal end portion of the endoscope insertion portion, the temperature of the endoscope insertion portion lowers, so that the objective lens and the lens frame. Although it is possible to cool the image fiber, light guide fiber, and adhesive parts to prevent deformation and melting, the lens frame could not be cooled to a temperature at which it does not change due to thermal expansion. Image blurring occurs.

Further, as disclosed in Japanese Patent Laid-Open No. 3-216614, when a thermal expansion and contraction absorbing portion is provided in a metal protective tube and a quartz glass system is used for an objective lens and an image fiber, breakage of the image fiber is prevented. However, the expansion of the objective lens can be reduced, but the objective lens frame thermally expands, the distance between the lenses changes, and the image blur occurs. In addition, when the insertion part is made flexible, the metal protection tube must be switched to a silicon tube or the like. Therefore, the above-mentioned "Metal protection tube is equipped with a thermal expansion and contraction absorption part to prevent breakage of image fiber" is inserted. Not applicable when the part is flexible.

Further, as disclosed in Japanese Unexamined Patent Publication No. 6-186466, in the technology for photographic cameras and television cameras for reducing the amount of change in the image forming position due to temperature change, the main lens barrel is a lens holding lens barrel. Since it is on the outside, it requires a wider installation space compared to the inside of the distal end of the endoscope insertion part having a small outer diameter and a small installation space, which makes it difficult to adopt the above structure for an endoscope. It was

The present invention has been made in view of the above circumstances, and when the endoscope is used under high temperature, the lens frame constituting the observation optical system disposed in the endoscope insertion portion is thermally expanded. It is an object of the present invention to provide an industrial endoscope that prevents image blurring that occurs.

[0018]

The industrial endoscope according to the present invention is an industrial endoscope for carrying out an inspection under high temperature in which an observation optical system constituted by combining a plurality of lenses is arranged at the distal end portion of the endoscope. In the endoscope, the plurality of lenses are arranged in at least two lens frames formed of members having different thermal expansion coefficients to form an observation optical system.

According to this structure, one set of lenses, which change the inter-lens distance and affect the focal length at high temperature, are fixed to different lens frames, respectively.
Even if each lens frame is exposed to high temperature and thermally expands, the change in length due to the thermal expansion of the lens frame is offset and the distance between the lenses is always kept constant, so that the best focus state is maintained.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention. FIG. 1 is a diagram for explaining a schematic configuration of an industrial endoscope apparatus and an operation of the industrial endoscope, and FIG. 2 is an industrial endoscope. 3 is a cross-sectional view illustrating the configuration of an observation optical system provided in FIG.

As shown in FIG. 1, the industrial endoscope apparatus 1 comprises:
As an industrial endoscope, for example, it is a device that inserts the endoscope insertion portion 21 from the inspection hole 31 of the gas turbine engine 3 and inspects and observes the turbine blade 32 at a high temperature, and has an elongated and flexible structure. Endoscope insertion part 2 having
1, a fiberscope 2 having an observation optical system and an illumination optical system built-in, a light source device 4 for supplying illumination light to the illumination optical system of the fiberscope 2, and a fiberscope 2 mounted on the fiberscope 2 to image an observation target site. It is composed of a TV camera 5 and a monitor 6 such as a liquid crystal TV that displays an observation image of an observation target portion imaged by the TV camera 5. The object to be inspected is not particularly limited to the gas turbine engine, but is a structure such as a jet engine having a high temperature inside.

The endoscope insertion portion 2 of the fiberscope 2
1 is configured by connecting a tip portion 26, a curved portion 27, and a flexible portion 28, and has an outer diameter dimension and flexibility that can be inserted into the gas turbine engine from an inspection hole 31 of the gas turbine engine 3. There is. An operating portion 22 provided with an angle knob 24 that bends the bending portion 27 to orient the distal end portion 26 in a desired direction is connected to the proximal end portion of the endoscope insertion portion 21, and this operation is performed. An eyepiece portion 23 for observing an image of an observation target portion captured by an observation optical system with the naked eye is disposed behind the portion 22. The TV camera 5 is detachably connected to the eyepiece 23 via a photographing adapter 51.

An eyepiece lens (not shown) is provided in the eyepiece 23.
Is provided on the eyepiece lens so that the image of the observation target portion captured by the distal end portion 26 is formed by being transmitted through an image guide described below which is inserted through the endoscope insertion portion 21 and the operation portion 22. Has become.

The photographing adapter 51 is connected to the eyepiece 23 by, for example, a bayonet, and is connected to the TV camera 5 by a C mount screw (having a male screw on the photographing adapter 51 side,
It has a female screw on the TV camera side). The photographing adapter 51 is provided with a photographing lens (not shown), and the image of the observation target portion formed on the eyepiece 23 is transmitted to the TV camera 5.

The TV camera 5 has a C mount screw portion 5
2 and a solid-state image sensor described later is built in the camera. The image transmitted to the photographing adapter 51 via the image guide or the like is formed on the solid-state image sensor by the photographing lens. The TV camera 5 is connected to the CCU 55 via the CCU connector 54 provided on the universal cable 53. Therefore, the optical image formed on the solid-state image pickup device is converted into an electric signal by the solid-state image pickup device and transmitted to the CCU 55 through a signal line inserted through the universal cable 53. This CCU5
At 5, the electric signal is converted into a video signal and output to the monitor 6, and the observation image captured by the fiberscope 2 is observed on the monitor 6. In the present embodiment, the image of the observation region is observed on the monitor 6, but in the case of visual observation, the inspector looks through the eyepiece 23.

Further, from the side portion of the operating portion 22, a tip end portion 26 has an emitting end, and the endoscope insertion portion 21 and the operating portion 22 are provided.
A light guide cable 41, which has a built-in light guide (not shown) that constitutes an illumination optical system that emits the illumination light necessary for observation from the emission end, extends through the end of the light guide cable 41. A light source connector 42 provided in the section is detachably connected to the light source device 4.

Although the industrial endoscope is a flexible endoscope in this embodiment, it may be a rigid endoscope. Further, the industrial endoscope may be a fiberscope or an electronic endoscope.

Here, referring to FIG. 2, the endoscope insertion portion 21
The observation optical system provided at the tip portion 26 will be described. As shown in the figure, the observation optical system 60 includes a first lens frame 61, a second lens frame 62, and each lens frame 61, 6
The optical system and the image guide 63 arranged in No. 2 are mainly configured.

The first lens frame 61 is arranged with respect to the distal end constituting member 26a which constitutes the distal end portion 26 of the endoscope insertion portion 21, and has a linear expansion coefficient of 11.8 × 10.
-6 iron member. On the other hand, the second lens frame 62 is
It is a brass member that is arranged with respect to the first lens frame 61 and has a linear expansion coefficient of 17.5 × 10 −6. That is, the observation optical system 60 of the present embodiment is composed of the first lens frame 61 and the second lens frame 62 formed of members having slightly different linear expansion coefficients.

The first lens frame 61 has a tip forming portion 2
The first screw 64 is attached to the thread formed on the tip of 6a.
By screwing and pressing the outer peripheral surface of the thick portion 61a near the tip of the first lens frame 61,
It is integrally fixed to a.

On the other hand, the second lens frame 62, which is inserted from the rear side of the first lens frame 61, has a second screw on a screw portion formed at the rear end portion of the first lens frame 61. 6
5 is screwed to press the outer peripheral surface of the large diameter portion 62a in the vicinity of the rear end portion of the second lens frame 62, whereby the second lens frame 62 is integrally fixed to the first lens frame 61.

A cover glass 66 and a first plano-convex lens 67 are adhered and fixed to the inner peripheral surface of the first lens frame 61 on the tip side. A large-diameter portion 68a of a base 68 into which an image guide 63 is inserted is adhesively fixed to the inner peripheral surface of the second lens frame 62 on the tip side. The rear end surface of the second plano-convex lens 69 is adhesively fixed to the front end surface of the base 68 into which the image guide 63 is inserted.

The observation optical system 6 constructed as described above is used.
The distance from the rear end face of the first plano-convex lens 67 of 0 to the center position of the screw 65 is L1, and the distance from the tip face of the second plano-convex lens 69 to the center position of the second screw 65 is L2. Rear end face of the second plano-convex lens 67 and the second plano-convex lens 69
Let Ls be the distance between the lens and the front end surface of.

Further, the parts of the endoscope insertion portion 21 which is a main heated portion of the fiberscope 2 are made of quartz glass for lenses, Teflon for resin material, and ceramic adhesive (alumina, for adhesive). Inorganic adhesives such as magnesia and zirconia bases) are used to form heat resistant members.

Further, an observation optical system 6 is provided at the tip portion 26.
In addition to 0, the light emitting end of a light guide (not shown) is provided on the front end face, and the curved portion 27 is connected to the rear end.

The operation of the observation optical system arranged at the tip of the industrial endoscope configured as described above will be described. For example, in order to inspect and observe the turbine blade 32, the endoscope insertion portion 21 is inserted from the inspection hole 31 of the gas turbine engine 3. Then, the temperature of the tip portion 27 inserted into the gas turbine engine 3 becomes high, and the first lens frame 61 and the second lens frame constituting the observation optical system 60 disposed at the tip portion 27 are formed. 62 is heated and the first lens frame 61 and the second lens frame 62 are heated.
Both of them undergo thermal expansion, and the total lengths thereof change with respect to the second screw 65. The change amount of the first lens frame 61 due to thermal expansion at this time is Δa, and the second lens frame 62 is
Let Δb be the amount of change in the distance Ls between the first plano-convex lens 67 and the second plano-convex lens 69 before thermal expansion.
, Ls = L1−L2, while the inter-lens distance Ls ′ after thermal expansion is Ls ′ = (L1 + Δa) −
(L2 + Δb).

At this time, the amount of change due to thermal expansion between the first lens frame 61 and the second lens frame 62 is determined by the linear expansion coefficient of the material forming the lens frame and the length of the lens frame.

The relationship between the length of the first lens frame 61 and the length of the second lens frame 62 is such that the length of the first lens frame 61> the length of the second lens frame 62. .

On the other hand, the first lens frame 61 is made of iron, the linear expansion coefficient is 11.8 × 10 −6, the second lens frame 62 is made of brass, and the linear expansion coefficient is 17.5. × 10
-6.

That is, since the linear expansion coefficient of the second lens frame 62 having a short lens frame length is larger than the linear expansion coefficient of the first lens frame 61 having a long lens frame length, the first lens frame 61 and the second lens frame 61 The change amount Δa and the change amount Δb changed by thermal expansion with the lens frame 62 become almost the same value, and the change amount is offset. Therefore, the inter-lens distance Ls before thermal expansion and the inter-lens distance Ls ′ after thermal expansion have the same size.

As described above, the lens frame constituting the observation optical system of the industrial endoscope for inspecting a portion reaching a high temperature
And the second lens frame, the first lens frame and the second lens frame are formed in consideration of the total length of the lens frame and the linear expansion coefficient of the member forming the lens frame. By doing so, the inter-lens distance between the optical system arranged in the first lens frame and the optical system arranged in the second lens frame can be always maintained at a constant interval. As a result, the image blur caused by the change in the inter-lens distance is eliminated.

In the present embodiment, the material of the first lens frame is iron and the material of the second lens frame is brass. However, the material of the first lens frame and the second lens frame is When selecting, consider the length of each lens frame,
A material having an appropriate coefficient of linear expansion may be selected. As a result, it is possible to set the inter-lens distance before thermal expansion and the inter-lens distance after thermal expansion to be approximately the same size.

Further, the first plano-convex lens and the second plano-convex lens
Strictly speaking, the plano-convex lens of causes thermal expansion. However, since each lens is made of quartz glass, the coefficient of linear expansion of the quartz glass is 0.54 × 10.
Since it is -6, not only the amount of change in the lens thickness due to the thermal expansion of the metal such as iron and brass forming the lens frame is small, but also the thickness of the lens itself is the length L1. , L2 is much smaller than
The thermal expansion of the plano-convex lens and the second plano-convex lens is within a negligible range.

FIG. 3 is a sectional view for explaining the structure of the observation optical system provided in the industrial endoscope according to the second embodiment of the present invention. As shown in the figure, the observation optical system 70 of the present embodiment is different from the observation optical system 60 of the first embodiment in that an image guide 63 is inserted inside the second lens frame 71. The rear end surface of the second plano-convex lens 69 is fixed to the front end surface of the second lens frame 72. And
The first lens frame 71 is made of carbon steel having a linear expansion coefficient of 10.7 × 10 −6, and the second lens frame 72 is made of carbon steel having a linear expansion coefficient of 1
It is made of 6.5 × 10 −6 copper. Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals and description thereof will be omitted.

As described above, by eliminating the die from the members constituting the observation optical system, not only the number of parts is reduced and the diameter of the observation optical system can be reduced, but also the number of assembling steps can be reduced. . As a result, the proportion of the observation optical system in the tip configuration part is reduced, the area occupied by other members such as the light guide is increased to increase the amount of illumination light, and the outer diameter of the tip part is reduced. Will be possible.
Other functions and effects are the same as those of the first embodiment.

By the way, when the inspection is performed by inserting the endoscope insertion portion into the inspection site under high temperature, even if the endoscope insertion portion is made of a member having high heat resistance, The entire mirror insertion part becomes hot, and this heat is conducted to the operating part, which may cause burns to the operator, or deformation or melting of parts made of low heat-resistant resin that compose the operating part. is there. Therefore, when performing endoscopy at high temperature,
There has been a demand for an industrial endoscope in which a heat countermeasure is taken so that an operator is not burned or the components constituting the operation unit are not adversely affected by heat.

The connection between the rear end portion of the endoscope insertion portion 21 and the front end portion of the operation portion 22 will be described with reference to FIG. As shown in the figure, the rear end portion of the flexible portion 28 that constitutes the rear side of the endoscope insertion portion 21 is adhesively fixed to the connecting member 73 that is a heat radiating means. On the other hand, a heat insulating member 74 is arranged as a heat insulating means between the flange portion 73a provided on the proximal side of the connecting member 73 and the flange portion 22b provided on the distal end side of the jetter 22a forming the operation portion 22. , And is fixed integrally with the third screw 75.

The connecting member 73 is made of a material having a high thermal conductivity, such as brass, and a heat radiating plate 73b is provided on the outer peripheral portion of the connecting member 73.
The heat insulating member 74 is formed of a material having a high heat insulating property, such as a ceramic material. Further, the tip end side of the operation portion 22 gripped by the worker is the heat insulating member 74.
Is in contact with

By constructing the connecting portion between the rear end portion of the flexible portion 28 and the distal end portion of the operating portion 22 as described above, the endoscope insertion portion 21 is heated to a high temperature, and this heat is generated. Two
The heat is transmitted to the connecting member 73 by being conducted to the second side.

Then, the heat transmitted to the connecting member 73 is first radiated into the air through the heat radiating plate 73b.
However, if heat is continuously conducted to the connecting member 73, the heat radiation by the heat radiating plate 73b cannot catch up and the temperature of the connecting member 73 rises to some extent. In this case, since the heat insulating member 74 is arranged between the connecting member 73 and the operating portion 22,
The heat is hardly transferred to the heater 22a that constitutes the operation portion 22, and the operation portion 2 is in contact with the heat insulating member 74.
The temperature of 2 does not rise.

As described above, the heat radiating means is provided at the connecting portion between the inserting portion and the operating portion, and the heat insulating means is provided between the connecting member constituting the heat radiating means and the operating portion. It is possible to reliably prevent the heat conducted to the operating portion. As a result, the heat of the endoscope insertion part is not transferred to the operation part when performing an endoscopic examination of a part that reaches a high temperature, so that the operator's burns or the parts constituting the operation part are deformed or melted by the heat. To prevent it.

As shown in FIG. 5, the heat insulating member 76, which is a heat insulating means, is formed of a metal member, and a plurality of through holes 76a are provided in the heat insulating member 76, so that the through hole 76 is formed.
Heat can be released from a. Also, the through hole 76a
This reduces the cross-sectional area and reduces heat conduction to provide adiabatic effect. As a result, since the heat insulating member 76 is made of metal, the strength of this portion is increased and the strength of the operating portion 22 is improved.

Now, the camera 5 will be described with reference to FIG. The focal length of a CCD camera provided with a C-mount screw portion is adjusted by adjusting the position of the CCD and fixing it at the time of manufacturing the camera. Therefore, if the fiberscope or mount adapter to be combined with the camera changes, the focal length shifts and the user cannot adjust it. Therefore, there has been a demand for a camera that allows the user to adjust the focal length without being affected by the fiberscope or mount adapter that is combined with the camera.

FIG. 6 is a cross-sectional view for explaining the schematic structure of the TV camera 5 including the C-mount screw portion 52 serving as the connection portion with the photographing adapter 51 shown in FIG. 1 and the solid-state image pickup device 101.

As shown in FIG. 6A, the camera 5 of this embodiment
The focus cylinder 103 provided with the solid-state image sensor 101 for converting the optical image formed on the image pickup surface into an electric signal on the inner peripheral surface of the frame 102 can be fixed by adjusting the position in the front-rear direction with the screw 104. ing. A signal line 105 extending from the solid-state image sensor 101 and transmitting an electric signal.
Is inserted into the universal cable 53 and the CCU
55.

A lens receiver 107 to which a cover glass 106 is adhered and fixed is fixed to the tip of the frame 102, while the C mount screw portion 52 is slidably attached to the outer peripheral portion of the frame 102 on the tip side. .

The side surface of the C mount screw portion 52 is shown in FIG.
A long hole 108 as shown in B is machined, and a pin 109 is arranged in the long hole 108 so that the C mount screw portion 52 does not rotate with respect to the frame 102.

A large diameter portion 1 is formed on the outer peripheral surface of the frame 102.
02a is formed, and a ring 110 is rotatably externally fitted to the large diameter portion 102a. This ring 11
0 is restricted from dropping toward the tip side by the protrusion 102b of the large diameter portion 102a, and the cover 111 fixed to the frame 102 on the rear end face of the ring 110.
The front and rear positions are determined by contacting each other.

A female screw portion provided on the inner peripheral surface of the ring 110 and a male screw portion provided on the outer peripheral surface of the C mount screw portion 52 are screwed together to form the ring 11
By rotating 0, the C mount screw portion 52
Is designed to slide back and forth without rotating.

In the TV camera 5, the focal length (17.526 mm) from the tip surface of the C mount screw portion 52 to the image pickup surface of the solid-state image pickup device 101 is defined by the standard. As one method of accurately adjusting the focal length, the screw 1 is used.
The focus cylinder 103 is slid by the operation of 04, and the adjustment of the focal length by the screw 104 is T
This can be done only when the V camera 5 is manufactured.

In the present embodiment, another method of adjusting the focal length is to slide the C mount screw portion 52 by rotating the ring 110. The C-mount screw portion 52 can be easily slid and adjusted by the user.

Therefore, even if the focal length is deviated due to the influence of the fiberscope 2 combined with the TV camera 5 or the photographing adapter 51, the user can rotate the ring 110 to adjust the focal length. You can

This adjustment can be performed without rotating the image even when the image pickup adapter 51 is connected, that is, when the image of the fiberscope 2 is being checked on the monitor 6. This is the C mount screw part 52
Is not rotated.

By the way, the signal line 105 from the solid-state image pickup device 101 is inserted into the universal cable 53 and is connected to an electric contact (not shown) at the CCU connector 54. The CCU connector 54 is connected to the CCU 55.
Is electrically connected to each other, so that the solid-state image sensor 101 is connected to the electric circuit of the CCU 55.
The electric signal transmitted from is input.

In FIG. 1, the fiberscope 2 is connected to the light source device 4, and the TV camera 5 is connected to the CCU 55. Generally, in consideration of workability, since the light source device 4 and the CCU 55 are placed close to each other, it is desirable that the light guide cable 41 and the universal cable 53 have substantially the same length when operating the endoscope 2. It was

For example, assume that the light guide cable 41 and the universal cable 53 each have a length of 2 m. Considering economy, CCU55 is TV camera 5
It is generally a dedicated electronic endoscope, not a dedicated one. However, the CCU cannot be driven except for the solid-state image pickup device having a signal line of a fixed length, because the timing of the video signal is misaligned. In the electronic endoscope dedicated to the CCU 55, the length of the insertion portion is, for example, 2 m, the length from the operation portion to the CCU (the length of the CCU cable) is 3 m, and the total length of the signal line is about 5 m.

Therefore, the solid-state image pickup device which can drive the CCU 55 has a signal line of 5 m. This CCU5
In order to drive the solid-state image pickup device 101 of the TV camera 5 using the signal line 5, the length of the signal line 105 must be 5 m.

However, as described above, the length of the universal cable 53 of the TV camera 5 is 2 m, and the signal line 105 cannot be simply inserted and stored in the universal cable 53. I have to absorb the extra length somewhere.

Therefore, as shown in FIG. 7, the signal line 105
Are bound by a folding band 121, and the solid-state image sensor 1
The signal line 105 from 01 to the CCU connector 54 is folded so as to have a length of about 2 m and inserted into the universal cable 53.

As a result, the universal cable 53
Can realize a TV camera that is easy to use and can use the CCU 55 that is common to the electronic endoscope.

[Additional Notes] 1. In an industrial endoscope for inspection at high temperature, which has an observation optical system configured by combining a plurality of lenses at the distal end portion of the endoscope, the plurality of lenses are formed of members having different thermal expansion coefficients. An industrial endoscope which is arranged in at least two lens frames and constitutes an observation optical system.

2. A second lens frame, to which the rear lens is fixed, is arranged on the inner peripheral surface of the first lens frame, to which the front lens, which constitutes the observation optical system, is fixed. The industrial endoscope according to appendix 1, wherein the rear end portion is fixed to the first lens frame.

3. The industrial endoscope according to Appendix 2, wherein an image guide is inserted in the second lens frame.

4. The industrial endoscope according to Appendix 1, wherein the linear expansion coefficient of the lens frame is set in consideration of the frame lengths of the first lens frame and the second lens frame.

5. 5. The industrial endoscope according to Appendix 4, wherein the lens frame having a short frame length is formed of a member having a large linear expansion coefficient.

6. 2. The industrial endoscope according to appendix 1, wherein a heat radiating means and a heat insulating means are provided between the endoscope insertion portion and the operation portion of the industrial endoscope.

7. 7. The industrial endoscope according to appendix 6, wherein the heat radiating means is a connecting member formed of a metal member having high thermal conductivity, and a plurality of heat radiating plates are formed on the outer circumference of the connecting member.

8. 7. The industrial endoscope according to appendix 6, wherein the heat insulating means is a ceramic material having a high heat insulating property.

9. 7. The industrial endoscope according to appendix 6, wherein the heat insulating means is a metal member, and a plurality of through holes are formed in the metal member.

[0080]

As described above, according to the present invention, when the endoscope is used at a high temperature, the lens frame constituting the observation optical system disposed in the endoscope insertion portion is thermally expanded. It is possible to provide an industrial endoscope that prevents image blurring that occurs.

[Brief description of the drawings]

FIG. 1 and FIG. 2 relate to a first embodiment of the present invention, and FIG. 1 is a diagram illustrating a schematic configuration of an industrial endoscope apparatus and an operation of the industrial endoscope.

FIG. 2 is a cross-sectional view illustrating the configuration of an observation optical system provided in an industrial endoscope.

FIG. 3 is a cross-sectional view illustrating the configuration of an observation optical system provided in an industrial endoscope according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a connection between a rear end portion of an endoscope insertion portion and a distal end portion of an operation portion.

FIG. 5 is a cross-sectional view illustrating a state in which another heat insulating unit is provided at a connecting portion between the rear end portion of the endoscope insertion portion and the distal end portion of the operation portion.

FIG. 6 is a cross-sectional view illustrating a schematic configuration of a TV camera including a solid-state image sensor and a C-mount screw portion that is a connection portion with a shooting adapter.

FIG. 7 is an explanatory view showing a state in which signal lines are bundled in a universal cable for matching.

FIG. 8 is a cross-sectional view illustrating a configuration of a conventional observation optical system of an industrial endoscope.

[Explanation of symbols]

 60 ... Observation optical system 61 ... First lens frame 62 ... Second lens frame

Claims (1)

[Claims] 1. An industrial endoscope for performing an inspection under high temperature, wherein an observation optical system configured by combining a plurality of lenses is arranged at a distal end portion of the endoscope, wherein the plurality of lenses have a coefficient of thermal expansion. An industrial endoscope characterized in that the observation optical system is configured by arranging the observation optical system in at least two lens frames formed of different members.