JP2002040335A - Conduit inside surface inspection apparatus using mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the likelihood ratio of abnormal point discovery in inspection by making it possible to obtain images diametrically opposite to the side walls in a conduit without requiring the skill of an inspecting person needed heretofore, to eliminate the need for intricate operation in inspection work and to make the construction of the above device simple. SOLUTION: The optical image of a front subject is formed in the central part of an imaging element 423 through a concave lens 700. The optical images of the subject in the side parts are reflected by a main mirror 411 and a sub- mirror 601 and are formed around the central part of the imaging element 423. The apparatus is so constituted that the optical images formed around the central part are made into the uniform images free of distortion nearer the outer peripheral side by selecting the curvature of the main mirror and the sub-mirror.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the inner surface of a sewer using a mirror effective for inspecting the inner wall of a sewer such as a gas pipe, a water pipe, a sewer pipe and the like.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for inspecting the inner surface of a sewer,
There is a device that inserts a robot equipped with a television camera into a pipe, captures an image of the inner surface of the sewer, and projects and monitors this captured image signal as an image on a monitor provided outside.

FIG. 5 shows an overview of the robot. In front of the robot 100, a camera head 10
The camera head 101 is mounted on the drive unit main body 1.
02 support. The drive unit main body 102 is provided with a plurality of wheels 103, and the wheels 103 are driven by a motor. As a result, the robot 100 can travel inside the sewer. A television camera is provided inside the camera head 102, and by switching a mirror, an image of the front can be taken, and an image of the side can be taken. Reference numeral 104 denotes a camera cable for guiding an image signal to the outside.

The above-mentioned robot 101 has a problem that the field of view is narrow, and an optical system for solving this problem has been developed.

FIG. 6 shows an example of an optical system for expanding the field of view. Describing the basic configuration in principle, a mirror 202 having a convex surface facing the camera 201 and having an opening in the center is arranged in front of the imaging surface of the camera 201. On this mirror 202, an image of the pipe wall of the sewer 20 is shown. Then, this mirror 202 is arranged in the field of view of the camera 201. With such a configuration, the visual field range W1 is expanded, and the front and side walls can be inspected.

[0006] However, in the inspection apparatus in the sewer of this configuration, since the field of view by the mirror 202 is located on the side and rear of the inspection apparatus, a direct-view image and
When taking a correspondence with the side-view video, it is necessary to recognize the positional deviation while recognizing the positional deviation. In addition, there is a problem that the mirror image is inverted.

In order to solve such a problem, further improved optical systems have been developed.

FIG. 7 shows the basic configuration. In front of the imaging surface of the camera 301, a main mirror 302 having a convex surface facing the opposite side of the camera 301, that is, forward, and having an opening in the center is arranged. Further in front thereof, a concave lens 303 is provided at the center, and a small auxiliary mirror 304 having a convex surface facing the main mirror 302 is arranged around the concave lens 303. The field of view of the camera 301 passes through the opening of the main mirror 302 and passes through the sub-mirror 30.
4 is set.

In this manner, the field of view W2 of the main mirror 302 becomes the front side wall in the duct, and its image is displayed on the sub mirror 304. The secondary mirror 304 is a camera 3
Since it is within the visual field of 01, in this case, the front side wall of the inner surface of the sewer can be imaged. Further, the direct-view video is captured through the concave lens 303.

[0010] According to the apparatus for inspecting the inner surface of a sewer, the image of the side wall is not inverted. In addition, the front tube wall can be photographed. However, according to this inspection device, the captured image is, as captured with a fisheye lens, the center of the image is:
Although an image is captured with relatively little distortion, there is a problem in that the image is reduced (shrinked) with distortion as the image becomes closer to the periphery. This is because the viewing angle was expanded as much as possible.

[0011]

As described above, according to the conventional pipe inner surface inspection apparatus, each apparatus has a disadvantage. That is, the apparatus shown in FIG. 5 has a problem that the visual field range is narrow. In addition, in the case of the apparatus of FIG. 6, the imaging range of the inner surface of the tube wall is behind the apparatus. There is a problem that the captured video is inverted. Furthermore, the apparatus of FIG. 7 has a problem that the peripheral portion of the image becomes a contracted image, and it is difficult for the inspector to determine the shape of the fine scratch on the tube wall.

As a result, in the case of the conventional apparatus, the finding of an abnormal portion of the sewer depends on the quality of the operator at the site. In addition, since the finding of an abnormal portion of the sewer is performed by observing the image of the tube wall obliquely (not directly facing), which is called direct vision, the accuracy of the finding is low. Furthermore, if a method of stopping the robot after switching to the side view and rotating the camera after finding the abnormal point, a long time is required for the inspection. In addition, since the robot needs to perform a switching operation between direct vision and side vision, an operation of focusing, and the like, the structure of the robot body becomes complicated, and a failure is apt to occur accordingly.

Therefore, according to the present invention, (1) an image facing the side wall in the sewer can be obtained, (2) the skill of the inspector is not required as in the prior art, and (3) the inspection is performed. (4) Inspection work does not require a complicated operation,
(5) It is another object of the present invention to provide an apparatus for inspecting the inner surface of a sewer, which is simpler in structure and can reduce manufacturing costs.

[0014]

In order to achieve the above object, the present invention provides an image pickup device, a lens system disposed in front of the image pickup device along the optical axis of the image pickup device,
The part facing the front of the lens system is open, is arranged in front of the lens system, and faces the reflection surface to the front diagonal side,
A main mirror capable of projecting a region in a direction orthogonal to the front oblique side direction and the optical axis, and disposed in front of the main mirror, such that a mirror surface faces the main mirror side, and A portion facing the front of the lens system is open, and a sub-mirror that reflects an image of the main mirror and guides the lens system to the lens system is disposed in front of the sub-mirror, and is disposed facing the opening in front. An optical image which is taken in via the concave lens and is formed at the center of the image pickup device by selecting the curvature of the main mirror and the sub mirror, and the main mirror. Even if a portion due to a blind spot of an imaging area occurs between the optical image captured through the sub-mirror and formed around the central portion of the image sensor, the optical image guided to the image sensor is located on the outer peripheral side. Without distortion as you go Characterized by being configured such that the image.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention. In FIG. 1, reference numeral 400 denotes a cylindrical head housing having an axis X as a center. This head housing 400
A flange portion 401 is formed on the outer periphery of one end (rear end) of the rim. The other end (front end) of the head section housing 400 is cut off on the inner peripheral side to provide a locking portion.
Reference numeral 410 denotes a first internal holder, and a head housing 400
Is attached to the front opening of the vehicle and closes this opening. Here, the outer circumference of the first inner holding body 410 is locked by the locking portion, and a waterproof ring is disposed between the first inner holding body 410 and the inner circumference of the opening of the head housing 400.

The first internal holder 410 has a hollow centered on the axis X, into which the tip of the camera unit 420 is inserted and fixed from behind. This camera unit 4
The optical system 20 also has an optical system 421 centered on the axis X on the tip side, and an image sensor (eg, a CCD image sensor) 423 is provided at the rear. As the CCD image sensor, a device having 900,000 pixels is used, but a device having 400,000 pixels may be used.

Here, the first inner holder 410 has a conical mirror surface at the front peripheral surface. The following portion will be referred to as a main mirror 411. First internal holder 41
No. 0 has a flange 412 at the rear end, and the outer periphery of the flange 412 is inserted into the inner surface of the opening of the head housing 400.

Next, a flange formed integrally with the rear end of the substantially cylindrical cap 500 is fixed to the front surface of the flange 412 with screws or the like. The cap 500 is also coaxial with the axis X, and the main mirror 4 of the first internal holder 410
11 is provided. This part is transparent. For this reason, external light (light image of the tube wall) from the direction of the arrow indicated by the alternate long and short dash line can be taken and guided to the main mirror 411.

The tip of the cap 500 is formed thick. The front end of the cap 500 in the thick portion is provided with the shaft so that components can be inserted from the rear end.
A coaxial insertion hole is formed in X. The distal end of the insertion hole has a transparent bottom (window) 501. The second internal holder 600 is inserted into the insertion hole from the rear end of the cap 500 as a component. Therefore, the cap 5
00 has a large diameter on the rear end side and a small diameter on the front end side.

The second internal holder 600 is a transparent body,
Is provided with a ring-shaped reflecting surface (hereinafter, referred to as a sub-mirror) 601 at the rear end surface of the lens. Second internal holder 600
Has a concave lens 700 mounted coaxially at its tip.

Although not shown, the image pickup element 423
The imaging signal acquired in step (1) is guided to a video signal recording device (such as a VTR) via a camera cable and recorded.

FIG. 2 shows the field of view (FIG. 2 (A)) of the inspection apparatus having the above configuration, and the image of the image when the image captured by the camera unit 420 is viewed on the monitor screen 800 (FIG. 2 (B)). It shows the situation. According to this inspection apparatus, an image 801 captured in the forward visual field (V1) and an image 802 captured in the side visual field (V2) are displayed on the monitor screen 800, but are particularly captured in the side visual field (V2). The image 802 is not distorted as in the related art (as photographed with a fisheye lens). For example, if the object 830 on the side wall of the tube 840 is circular, the image 803 can be projected in a circular shape.

In this system, however, a blind spot range (between the images 801 and 802 on the monitor) is partially generated. This is advantageous in terms of inspection accuracy, and there is no problem in practical use. That is, in this system, a blind spot exists between the image 802 and the image 801 in the imaging area. However, at the expense of the occurrence of blind spots, the present invention focuses on making the inspection of the inner wall of the tube easy by looking at the monitor and improving the reliability of the inspection. By allowing the occurrence of a blind spot in this way, when selecting the curvature of the mirror surface of the main mirror 401, the monitor image can be made uniform without distortion toward the outer peripheral side. In other words, the focus is not only on enlarging the visual field range, but also on the image observed on the inspection being an image from which the shape and size of the subject can be accurately grasped.

The above-mentioned image on the monitor is equivalent to the fact that the optical image guided to the image pickup element becomes a uniform optical image without distortion toward the outer peripheral side.

The image to be captured if the user does not stick to the recording of the moving image may be a thinned-out moving image (continuous still image) in accordance with the speed of the traveling robot. In this case, a camera with a higher image quality may be used. it can.

FIG. 3A is a front view of the above-described inspection apparatus. A plurality of illuminators 900 are attached to a flange 401 of a head housing 400 behind the cap 500, And can illuminate the sides. FIG. 3B is a sectional view of one of the illuminators 900 taken out.
(A), a cross section taken along line AA).

It is difficult to uniformly illuminate a subject such as an inner surface of a sewer having a large difference in distance in a range where an image is captured with a normal illuminator. Therefore, in this inspection device, the lighting device 900 is also devised. That is, as shown in FIG. 3B, the opening side of the transparent cap 901 having a U-shaped cross section in the axial direction is placed on the cap holder 9.
02 is inserted into the circular insertion port. Further, a reflector 911 is attached to the cap holder 902 coaxially from the rear. This reflector 911 has a hollow, where the end of the elongated lamp 922 is located substantially. The distal end of the elongated lamp 922 extends forward in the transparent cap 901.

A lamp mounting board 923 is arranged behind the reflector 911. The lamp mounting board 923 is mounted on a fixing portion 924 provided at the rear thereof by screwing or the like. The lamp-facing surfaces 912 and 913 of the reflector 911 are formed such that the outside, that is, the lamp-facing surface on the side radiating from the axis X when the present inspection apparatus is inserted into the sewer is short in the axial direction. This is a slender lamp 92
This is for effectively emitting the second light in the emission direction.

The cap holder 902 is connected to the head housing 4.
00 outer ring portion 402 further formed on the outer periphery of collar portion 401
Is inserted inside. The outer ring portion 402 includes a flange portion 401.
Is formed so as to protrude forward and outward,
Together with the outer periphery of the head housing 400, a cap holder attaching portion is formed. At a contact portion between the outer ring portion 402 and the cap holder 902, a waterproof ring is provided. A screw groove is provided on the outer peripheral surface of the outer ring portion 402, and an adjusting ring 930 is screwed into the screw groove.

The tip of the adjusting ring 930 is engaged with the cap holder 902, and by rotating this, the position of the cap holder 902 can be adjusted back and forth (in the direction of the axis X).

In the apparatus of the present invention, the main mirror 41
1. By selecting the curvature of the reflection surface of the sub mirror 601,
The optical image guided to the image-forming surface of the image sensor was prevented from being distorted toward the periphery. This is to prevent the image on the monitor from becoming like an image captured by a fisheye lens.

However, electrical processing is possible without relying on the curved surface of the mirror. For example, a video signal captured by a conventional system is temporarily stored in memory, and in accordance with the reduction ratio, the image around the center of the image is stretched and processed. Can be modified into an image. However, since this method originally enlarges a portion where the information amount of the information source is small, the resolution is deteriorated. On the other hand, when an image without distortion is obtained by the primary mirror and the secondary mirror as in the present invention, a monitor image with good resolution can be obtained.

FIG. 4 shows an optical system 421 of the camera unit 420 used in the inspection apparatus of the present invention.

The lens of the optical system 421 includes the main mirror 41
0, the virtual image obtained by the sub-mirror 601 is
An image is formed on the imaging surface 3. Further, an image obtained by the concave lens 700 is formed on the imaging surface. Here, the lens is shown in FIG.
As shown in (B), the optical image from the concave lens 700 is formed at the center of the imaging surface, and the main mirror 410 and the sub mirror 6 are formed.
The optical image obtained in step 01 is formed around the central portion without distortion. The lens system is designed to maximize the characteristics of the mirror. Preferably, the lens has a higher resolution at the periphery than at the center. It is preferable that the optical design be made in accordance with the position of the virtual image of the mirror and the curvature of the mirror. Further, it is preferable that the concave lens 700 is designed so that an object at infinity can be imaged on the imaging surface.

In the above embodiment, in order to make the configuration as simple as possible, the primary mirror 411 and the secondary mirror 60 are used.
1 has been described as being integral with the first holder and the second holder, respectively. However, the present invention is not limited to this, and it goes without saying that the mirror component may be provided as a component separate from the holder.

As described above, this inspection apparatus can continuously obtain a clear image in which the inner surface of the pipe is always directly faced, and all parts are uniformly focused. Therefore,
Without leaving the discovery of the abnormal location to the on-site operator,
By playing back the recorded video, anytime, anywhere,
For example, a specialized inspector can check for abnormalities in the office. In addition, the on-site investigation work can be significantly reduced, and various adverse effects such as traffic congestion on public roads can be reduced. In addition, the structure of the inspection robot does not require a motor or a mechanical component for driving the optical system, and can be a very simplified structure. As a result, the frequency of failures that deteriorate working efficiency is significantly reduced. Also, running costs including policy costs and repair costs are reduced, making the device useful for users.

[0038]

As described above, it is possible to obtain an image facing the side wall in the pipe. Therefore, the skill of the inspector is not required unlike the conventional technique. Further, it is possible to improve the accuracy of finding an abnormal part on the inspection. Further, in the inspection work, the entire circumference in the pipe can be easily made an inspection image without requiring a complicated operation. In addition, the structure is simplified, so that manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a visual field range of a device of the present invention and an image on a monitor.

FIG. 3 is an explanatory view showing an attached state of an illuminator according to the device of the present invention.

FIG. 4 is an explanatory view showing an example of an optical system of a camera unit according to the apparatus of the present invention.

FIG. 5 is an explanatory diagram showing an overview of a conventional in-pipe inspection robot.

FIG. 6 is a diagram illustrating the principle of an optical system in a camera head of a conventional robot having a wide field of view.

FIG. 7 is a diagram illustrating the principle of an optical system in a camera head of a conventional robot in which a visual field range is similarly widened.

[Explanation of symbols]

 Reference numeral 400: head housing, 410: first internal holder, 411: main mirror, 412: flange, 420: camera unit, 421: optical system, 423: imaging element, 500: cap, 600: second internal holding Body 601: secondary mirror, 700: concave lens.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiichiro Togo 4-7-1, Asahigaoka, Hino-shi, Tokyo Inside Tokyo Electronics Industry Co., Ltd. (72) Akira Tanihiko 4-7-1, Asahigaoka, Hino-shi, Tokyo Tokyo Electronics Within Kogyo Co., Ltd. (72) Kazuharu Miyamoto 4-7-1, Asahigaoka, Hino-shi, Tokyo Tokyo Electronic Industry Co., Ltd. (72) Toshiyuki Exit 2-6-2 Otemachi, Chiyoda-ku, Tokyo Tokyo Sewerage Service Co., Ltd. (72) Inventor Hiroshi Saito 2-6-2 Otemachi, Chiyoda-ku, Tokyo Tokyo Sewerage Services Inc. (72) Inventor Kinshi 2-6-2 Otemachi, Chiyoda-ku, Tokyo Tokyo Sewerage Service Inside (72) Inventor Kenji Takizawa Within 2-11-10 Minamiazabu, Minato-ku, Tokyo Nippon Koei Co., Ltd. (72) Inventor Numa Shinji Oo 2304 Inarihara, Kashizaki-cho, Inashiki-gun, Ibaraki Pref. Nippon Koei Central Research Laboratory Co., Ltd. (72) Inventor Noriyuki Noriyuki 2304 Inarihara, Kinosaki-cho, Inashiki-gun Ibaraki Pref. Nippon Koei Central Research Laboratory Co., Ltd. F-term (reference) 2G051 AA82 AB07 AC17 BB01 BB11 CA04 CB01 CC09 CC11 FA02 2H040 AA02 BA01 BA02 CA03 CA25 DA12 GA02 GA03

Claims (5)

[Claims] An image pickup device, a lens system arranged in front of the image pickup device in alignment with an optical axis of the image pickup device, a portion facing the front of the lens system is open, and a front end of the lens system is opened. It is arranged, with the reflective surface facing the front diagonal side,
A main mirror capable of projecting an area in a direction perpendicular to the front oblique side direction and the optical axis, and disposed in front of the main mirror, such that a mirror surface faces the main mirror side, and The part facing the front of the lens system is open, reflects the image of the main mirror,
A secondary mirror leading to the lens system; and a concave lens disposed in front of the secondary mirror and opposed to the opening in front of the secondary mirror, wherein the curvatures of the primary mirror and the secondary mirror are selected. so,
An optical image captured via the concave lens and formed at the center of the image sensor, and an optical image captured via the main mirror and the sub-mirror and formed around the center of the image sensor. A tube using a mirror, wherein an optical image guided to the image sensor becomes a uniform image without distortion as it goes to the outer peripheral side even if a portion due to a blind spot of an imaging area occurs between the tube and the mirror. Drain inner surface inspection device. 2. The apparatus for inspecting an inner surface of a sewer using a mirror according to claim 1, wherein the main mirror has a convex surface in a forward oblique radial direction, and the convex surface orbits. 3. The inspection system according to claim 1, further comprising a cap surrounding the main mirror and the sub-mirror and having the convex lens. 4. The main member holds the unit of the image sensor in a hollow portion thereof, is mounted on a front opening of a cylindrical head housing, and also serves as a holder. An apparatus for inspecting the inner surface of a sewer using the mirror according to 1. 5. An outer periphery of a rear end of the head housing,
5. A flange is integrally formed, a plurality of illuminators are attached to the flange in a circumferential direction, and an illumination lamp of the illuminator is a lamp elongated in the front-rear direction.
An inner surface inspection apparatus for a sewer using the mirror described in the above.