Head for inner surface measuring device and inner surface measuring device

Abstract

To provide a head for measuring an inner surface having means for measuring a pipe shape and a pipe diameter in a curved pipe, or a device for measuring an inner surface.SOLUTION: A head for an inner surface measuring device includes a light irradiation part which is for irradiating the inner surface of a pipe with a planar light beam, an imaging part which has a camera for receiving scattered light from the inner surface of the pipe, and a holding part which is arranged between the light irradiation part and the imaging part and is for connecting the light irradiation part and the imaging part. The imaging part, the holding part, and the light irradiation part are arranged in order in a first direction. The holding part is configured so as to freely bend.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an inner surface measuring device head, and an inner surface measuring device including the inner surface measuring device head. [Background technology]

[0002] Patent documents 1 and 2 disclose an apparatus that has an inner surface measuring head equipped with a projection unit that projects light onto a plane and irradiates it inside the pipe, an imaging unit that images the light scattered by the pipe, and a fixing unit that holds the projection unit and the imaging unit as a single rigid body, and that can measure the shape of the inside of a pipe by inserting the inner surface measuring head into the pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-230301 A [Patent Document 2] Patent Publication No. 2021-113701 Summary of the Invention [Problem to be solved by the invention]

[0004] The above device can measure the inner shape of the pipe if it is straight. However, when it comes to curved pipes, it becomes physically difficult because the projection unit and the image capture unit of the inner surface measurement device are one rigid body.

[0005] The problem to be solved is to provide an inner surface measuring head or an inner surface measuring device having a means for measuring the shape or diameter of a pipe inside a bent pipe. [Means for solving the problem]

[0006] The head for an inner surface measuring device according to the present invention is a head for an inner surface measuring device for measuring the inner surface shape of a pipe, and includes a light irradiation unit for irradiating the inner surface of the pipe with a planar light beam, an imaging unit having a camera for receiving scattered light from the inner surface of the pipe, and a holding unit arranged between the light irradiation unit and the imaging unit for connecting the light irradiation unit and the imaging unit. The imaging unit, the holding unit, and the light irradiation unit are arranged in order in a first direction, and the holding unit is configured to be freely bent.

[0007] In the head for an inner surface measuring device according to the present invention, the imaging unit, the holding unit, and the light emitting unit are arranged in order in a first direction. The holding unit arranged between the light emitting unit and the imaging unit connects the light emitting unit and the imaging unit and is configured to bend freely, so that shape measurement data can be obtained inside a pipe with a bent tube, and the pipe dimensions, such as the diameter of the pipe, can be known. This is therefore useful for maintenance such as pipe maintenance or repair.

[0008] In addition, the head for an inner surface measuring device according to the present invention may further include an imaging unit housing for accommodating the camera. The imaging unit housing may have a window portion on a front side that is capable of transmitting the scattered light, and the holding portion may be attached and fixed to approximately the center of the window portion.

[0009] The inner surface measuring device head according to the present invention further includes an imaging unit housing for housing a camera, and this imaging unit housing has a window portion on the front side that is capable of transmitting scattered light, and the holder portion is attached and fixed to approximately the center of the window portion. As a result, the inner surface of the pipe photographed by the camera is generally on the periphery of the image, and the holder portion and the light irradiation portion can be disposed in the center of the image where the inner surface of the pipe is not present, so that imaging can be performed without the head for the inner surface measuring device itself becoming an obstacle.

[0010] In the head for an inner surface measuring device according to the present invention, the holding portion may include a pipe-shaped elastic member and have a generally conical shape with a diameter increasing from the imaging portion to the light irradiating portion in the first direction. By having the holding portion have a generally conical shape, multiple reflections of light irradiated from the light irradiating portion on the inner surface of the pipe can be reduced.

[0011] Furthermore, in the head for an inner surface measuring device according to the present invention, the light irradiation unit may have a light emitting element that emits light in the first direction, and a mirror unit that receives the light emitted from the light emitting element and reflects the light in a planar form, and the light reflecting surface of the mirror unit has an angle with respect to the first direction in the range of 45 degrees or more and 60 degrees or less. By having the light reflecting surface of the mirror unit have an angle with respect to the first direction in the range of more than 45 degrees and 60 degrees or less, the measurable area is increased even in measurement inside a pipe with an overhanging shape.

[0012] In the inner surface measuring device head according to the present invention, the camera of the imaging unit may have a lens, and an object distance of the lens may be approximately equal to a distance from the lens to the mirror unit. This allows imaging with reduced influence on imaging by the camera even if wiring or the like is routed at a position away from the object distance of the lens.

[0013] Furthermore, the inner surface measuring device according to the present invention can include the head for the inner surface measuring device described above, a memory unit that receives an image signal output from the head for the inner surface measuring device and stores the received image signal, a calculation unit that extracts a luminance distribution of the inner wall of the pipe from the image signal recorded in the memory unit and measures the shape of the inner surface of the pipe, and a display unit that outputs measurement values ​​from the calculation unit to the outside. Effect of the Invention

[0014] In the head for an inner surface measuring device according to the present invention, the imaging unit, the holding unit, and the light emitting unit are arranged in order in a first direction. The holding unit arranged between the light emitting unit and the imaging unit connects the light emitting unit and the imaging unit and is configured to bend freely, so that shape measurement data can be obtained inside a pipe with a bent tube, and the pipe dimensions, such as the diameter of the pipe, can be known. This is therefore useful for maintenance such as pipe maintenance or repair. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing an inner surface measuring head according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a simplified diagram showing the coordinates and directions of FIG. [Diagram 3] FIG. 3 is a diagram showing the state of the inner surface measuring head inside the pipe. [Figure 4] Figure 4(a) is a diagram defining the dimensions of the parts in Figure 1. Figure 4(b) shows an enlarged view of Figure 4(a). [Diagram 5] FIG. 5 is a diagram illustrating the configuration of the reflecting member. [Figure 6] Fig. 6(a) is a diagram showing the state of the light trace of the inner surface measuring head inside the pipe, and Fig. 6(b) is an enlarged view of the vicinity of the reflecting surface. [Figure 7] FIG. 7 is a partial view for explaining the wiring in FIG. [Figure 8] FIG. 8 is a diagram for explaining the configuration of the transparent window. [Figure 9] FIG. 9 is a diagram illustrating an inner surface measuring device according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of an image (photograph) taken when the inside of a pipe is photographed with a camera using the inner surface measuring head shown in FIG. [Figure 11] FIG. 11 is a diagram showing an example of an image (photograph) obtained when light is projected from the irradiation unit and camera illumination of the inner surface measuring head shown in FIG. 1 and the ring gauge is photographed. [Figure 12]Fig. 12 is a diagram for explaining prevention of multiple reflections of the inner surface measuring head shown in Fig. 1. In Fig. 12, a top view is shown in the upper part, and a front view is shown roughly in the lower part. [Figure 13] Fig. 13(a) is a diagram for explaining a light trail in an inner surface measuring device using a transparent fixture, and Fig. 13(b) is a cross-sectional view taken along line XIII-XIII in Fig. 13(a). [Figure 14] FIG. 14 is a block diagram of the inner surface measuring device according to the first embodiment. As shown in FIG. [Figure 15] FIG. 15 is a flowchart of the inner surface measuring method according to the first embodiment. [Figure 16] FIG. 11 is a schematic diagram showing an inner surface measuring head according to a second embodiment. [Figure 17] Fig. 17 is a diagram for explaining multiple reflections caused by the inner surface measuring head shown in Fig. 16. In Fig. 17, a top view is shown in the upper part, and a front view is shown roughly in the lower part. [Figure 18] Fig. 18(a) is a schematic diagram showing an inner surface measuring head according to a third embodiment, and Fig. 18(b) is a cross-sectional view taken along line XVIII-XVIII in Fig. 18(a). [Figure 19] FIG. 13 is a schematic diagram showing an inner surface measuring head according to a fourth embodiment. [Figure 20] Fig. 20(a) is a diagram showing the light trace when the inner surface measuring device head 1 is inserted inside a pipe with an overhang. Fig. 20(b) is a diagram showing the light trace when the inner surface measuring device head is inserted inside a pipe with an overhang. In Fig. 20(a), (a)-1 shows an enlarged view of reflection position P1, and (a)-2 shows an enlarged view of the vicinity of reflecting member 22. In Fig. 20(b), (b)-1 shows an enlarged view of reflection position P1, and (b)-2 shows an enlarged view of the vicinity of reflecting member 21-1. [Figure 21] FIG. 21 is a flowchart of the inner surface measuring method according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, and relative positions of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. The present invention is a device for measuring the shape and dimensions of the inner surface of a pipe, and the pipe is a building material related to piping, drainage, etc., an automobile part such as an automatic transmission oil passage, the inner surface of a ski boot, etc. Hereinafter, the positional relationship of each part will be described, but unless otherwise specified, the description will be given on the premise that each part is connected from the front to the rear.

[0017] (First embodiment) Fig. 1 is a schematic diagram of a pipe inner surface measuring device 1 (hereafter abbreviated as head 1) including a pipe inspection device according to the first embodiment, as viewed from the front, and Fig. 9 is a schematic diagram of a pipe inspection device including a pipe inspection device according to the first embodiment, as viewed from the front. The measuring device 1100 is configured as follows: (1) a light irradiation unit 2 that irradiates a planar light beam onto a measurement target, (2) an image capture unit 3 that observes light traces scattered by the measurement target, (3) a head 1 that is connected to the light irradiation unit 2 and the image capture unit 3 and is freely bendable, and (4) a scanning unit 5 that scans the head 1, and further includes (5) a product calculation unit 6 that receives an image signal output from the head 1 and stores the image signal, a calculation unit 62 that extracts the luminance distribution of the pipe inner wall from the image signal recorded in the storage unit and measures the pipe inner surface shape, and a display unit 63 that outputs the calculation result.

[0018] When head 1, which is made up of optical components, receives an external force, holding unit 4 bends, making it possible for head 1 to be sent into the inside of a pipe even if it is narrow and curved inside the pipe (see Figure 3). In addition, in terms of the arrangement of head 1, light irradiation unit 2 and holding unit 4 are arranged in front of the shooting surface of imaging unit 3, which at first glance seems like a design error in the mechanical configuration, but by arranging light irradiation unit 2 and holding unit 4 in an area that does not affect the measurement of the inside surface of the pipe, it is a head for an inner surface measurement device for measuring the shape of the inner surface of a pipe, which has the characteristic of effectively utilizing the field of view used for measurement. From here on, you will gradually understand as we explain each part in detail.

[0019] The light irradiation unit 2 is a member that projects a surface light beam, and in the first embodiment, it is a member that projects a planar light beam. The components of the light irradiation unit 2 are composed of a reflective member 21, a protective material 28, a light source 22, and an irradiation unit housing 23.

[0020] We will now explain the arrangement of the light source 22. The light source 22 is a light-emitting element that emits highly directional light, and emits a narrow, collimated point light source from the light-emitting unit E1. It is a component that has a light-emitting element such as a highly directional laser or LED.

[0021] Here, the first direction Ax1 and coordinates are defined. Figure 2 is a simplified diagram of Figure 1, showing an orthogonal coordinate system S, and the direction of the light ray BM emitted from the light-emitting unit E1 is defined as the first direction of the head 1. Also, z is the direction of the first direction Ax1, the X-axis in Figure 2 faces forward, and the Y-axis faces upward.

[0022] The structure of the reflecting member 21 will be described. The reflecting member 21 has two structures, 21a or 21b in FIG. 4. The reflecting member 21a will be described. The reflecting member 21a is composed of two parts: a cone-shaped part (1) with a reflecting surface at an angle of 45 degrees to the first direction Ax1, and a transparent tube (2) with an inner diameter equal to the diameter of the cylinder and a length several millimeters longer than the cylinder, on a cylindrical base with a predetermined height and diameter. The cone-shaped part (1) is inserted into the transparent tube (2), the end faces are aligned, and fixed by adhesive or the like. Next, 21b will be described. It is an optical component that is made by hollowing out a cylindrical member made of a light-transmitting material such as glass or transparent resin, and the reflective surface has a conical shape at an angle of 45 degrees with respect to the negative direction of the first direction Ax1, and the reflective surface of the cone causes total reflection.

[0023] Next, the structure of the mirror protection material 28 will be described. The shape of the mirror protection material 28 may be any shape that has a smooth outer diameter such as a hemisphere with the same length as the outer diameter of the reflecting member 21, and that adheres to the surface of the reflecting member 21 to give a smooth shape to the front part of the head 1. The material may be resin, metal, or the like, and is not particularly specified.

[0024] The connection between the reflecting member 21 and the irradiation unit housing 23a will be described. One end of the irradiation unit housing 23a is a cylinder whose inner diameter is approximately the outer diameter of the reflection member 21, and the reflection member 21 is structured to be inserted into the irradiation unit housing 23a, with the apex of the cone in the reflection member 21 facing backward, inserted into the irradiation unit housing 23a, and fixed with fixing parts such as screws. The method of fixing the reflection member 21 and the protective material 28 will be described. The end faces of both parts are circular surfaces of approximately the same diameter, and are fixed by bonding.

[0025] The reflecting member 21 is a component that generates a planar beam (hereafter referred to as a planar sheet PBM) when combined with a highly directional light source. The mechanism for generating the planar sheet PBM will be explained with reference to the enlarged view (a) of FIG. 6. The light beam emitted from the emission part E1 of the light source 22 is reflected off the inclined surface near the apex of the cone of the reflecting member 21, generating a planar sheet PBM that passes through the apex of the cone and passes on the xy plane, spreading radially from the apex of the cone. As this is a component that is already commercially available, further detailed explanation will be omitted.

[0026] The irradiation unit housing 23 is composed of two parts, the irradiation unit housing 23a and the irradiation unit housing 23b. The irradiation unit housing 23a is basically cylindrical, and the irradiation unit housing 23b is basically cylindrical with the same outer diameter as the irradiation unit housing 23a. The irradiation unit housing 23b is fixed to the rear end face of the irradiation unit housing 23a with screws or the like. The irradiation unit housing 23a is connected to the reflecting member 21 at the front, and the inner diameter of the irradiation unit housing 23a is the same as the outer diameter of the reflecting member 21. The reflecting member 21 is inserted into the irradiation unit housing 23a from the front and fixed by adhesive or the like, but the apex of the cone mirror of the reflecting member 21 needs to be outside the irradiation unit housing 23a. The inside of the irradiation unit housing 23a is hollow, and the light source 22 is inserted, and the position of the light source 22 is adjusted and fixed from the outside of the irradiation unit housing 23a with a set screw or the like so that a collimated light beam is emitted from the light emitting unit E1 of the light source 22 toward the apex of the cone. If the flat sheet PBM is not generated from the light irradiation unit after fixing, readjust or replace the parts. There is a female screw in the center of the irradiation unit housing 23b into which the elastic member 41 can be inserted, and the elastic member 41 is connected to the rear by screwing in the elastic member 41.

[0027] The imaging unit 3 is a member whose main component is a camera, which captures an image of a light trail on a measurement object, and is also a component that houses wiring, etc. The components of the imaging unit 3 are a camera 31, a camera light 37 attached to the side of the camera, a camera housing 33a and a camera housing 33b (camera housing 33a and camera housing 33b are collectively referred to as camera housing 33) that house the camera 31, and a conductor 34 that is installed on the inner surface of the camera housing 33a and organizes the wiring.

[0028] The camera 31 has an imaging element such as a CMOS or CCD camera, and is equipped with a so-called area camera that converts the light received by the imaging element into light and outputs it as an electric signal, and an objective lens. An opening is located at the position E2 on the camera 31, and the area camera is placed a predetermined distance behind the objective lens. The object distance of the condenser lens attached to the camera 31 is set to the distance from the center of the condenser lens to the tip of the reflecting surface of the reflecting member 21, so that the focus of the condenser lens is adjusted to the vicinity of the plane on the planar sheet PBM.

[0029] The camera 31 is a component installed inside the camera housing 33a, and the position of the camera 31 is adjusted and fixed from the outside of the camera housing 33a using fixing devices such as screws. As an example of the arrangement of the screws, six set screws are installed at three locations at approximately equal intervals on each of two arbitrary cross sections of the camera housing 33a that are approximately parallel to the xy plane, and while watching the image captured by the camera 31, the tightness of the set screws is adjusted so that a fixing device 42, which will be described later, appears in the center of the image. This is one example of the camera fixing 31, and the camera 31 may be fixed to the camera housing 33b, for example.

[0030] Fig. 6 is a schematic diagram of the reflecting member 21, light source 22, and camera 31 of the irradiation unit 2 when the head 1 is inserted into a measurement target W such as a pipe. The camera 31 is a component that scatters the flat sheet PBM projected from the reflecting member 21 on W and captures the scattered light. Fig. 10 shows an example of an image captured by inserting the head 1 into a pipe A1. The inner surface of the pipe is a closed space and is normally pitch black, but only the part where the flat sheet PBM touches the pipe becomes bright, so when the inside of the cylinder is captured, an image of a ring-shaped light trail that is close to a circle or ellipse can be captured against a pitch black background.

[0031] The camera lighting 37 is a small, non-directional light source such as an LED arranged around the camera. Figure 9 shows the camera lighting 37 arranged with multiple LEDs on a doughnut-shaped base, and installed around the camera 31 in a direction that illuminates the front. However, more than one LED is sufficient. The power supply for the camera lighting 37 is connected from the base to the positive power and ground wires of cable 51. The camera lighting 37 is used as lighting when observing the inside of a pipe. If only measuring the diameter or shape of a pipe, etc., it is a part that can be removed. LEDs are widely available on the market, so a detailed explanation will be omitted.

[0032] The camera housings 33a and 33b are components for assembling the imaging unit 3 as a single rigid body. They may be made of metal or resin. The shape of the camera housing 33a is basically a cylinder with an outer diameter r1 and an inner diameter r2, and the front end face is hollowed out to a cylindrical shape of the same order as the transparent window 43 (a cylinder with an outer diameter r0 (r2 < r0 < r1) and a thickness d4) described later so as to fit into the transparent window 43 (see FIG. 7). The camera housing 33b is a cylinder with the same outer diameter as the camera housing 33a, and has a connector attached or a hole for passing a cable 51 described later.

[0033] The fixing to the transparent window 43 is as described above with respect to the fixing method of the transparent window 43. The fixing to the camera 31 is as explained above with respect to the fixing method of the camera 31. The fixing of the camera housing 33a and the camera housing 33b is performed using screws or the like.

[0034] The arrangement of the conductor 34 will be described with reference to FIG. 7. The structure may be an eyebolt or other parts, or a groove may be provided inside the camera housing 33a, but the case of an eyebolt will be described here. It is desirable to insert the conductor 34 into the camera housing 33a at equal intervals for the number of electric wires 45 described later on a cross section inside the camera housing 33a, for example, about 10 mm in from the front of the camera housing 33a. Furthermore, the conductor 34 is also installed at a position moved parallel to the cross section, for example, 10 mm in from the rear of the camera housing 33a in the opposite direction to the first direction. The effect of the conductor 34 is to prevent the electric wire 45 described later located in front of the camera 31 from slackening.

[0035] The holding unit 4 is located between the light irradiation unit 2 and the imaging unit 3, and connects the two components together. It is also a freely bendable component that has the function of changing the relative positions of the light irradiation unit 2 and the imaging unit 3 and positioning each component in a position that has minimal effect on the measurement.

[0036] The elastic member 41 is a pipe-shaped component having an aerial portion, includes a coil spring as an elastic member, and satisfies the following conditions. The outer shape of the elastic member 41 is preferably that of a cylindrical elastic spring, and the outer diameter and pitch of the spring correspond to the outer diameter and pitch of a specific screw standard. The elastic member 41 has a hollow portion. A cable 44 for supplying power is passed through the hollow space of the elastic member 41. · Apply surface treatment such as blackening to prevent multiple reflections. The size of the elastic member 41 will be described later in the section "Considerations for ensuring the measurement range." The fixing device 42 is a screw with a through hole, and the diameter and pitch of the screw are a part that match the inner diameter and pitch of the elastic member 41.

[0037] The elastic member 41 is connected to the irradiation unit housing 23b at the front and to the transparent window 43 at the rear. The elastic member 41 is connected to the irradiation unit housing 23b by treating the outer shape of the elastic member 41 as a cylindrical male screw, and a corresponding female screw is provided at the center of the irradiation unit housing 23b, and is screwed in place using a nut or the like. The elastic member 41 is connected to the transparent window 43 by treating the inner surface of the elastic member 41 as a female screw at the center of the transparent window 43, and is attached to the transparent window 43 using a nut or the like. Furthermore, the inner surface of the elastic member 41 is fixed from the rear as a female screw using a fixing device 42 such as a through-hole screw.

[0038] Two effects of the elastic member 41 will be described. By bending, the head 1 can pass through the inside of a pipe, even if it is thin and curved. (1) Avoidance of optical obstacles by concentrating head 1 in a narrow range in the first direction Ax1. (2) · Anti-multiple reflection (3) The effect (1) of the elastic member 41 will be explained below. A comparison will be made with reference to FIG. 3 between the head 1 of the present invention and the head for the inner surface measuring device, which is a rigid body instead of an elastic body, and a force is applied from behind to a pipe W that is about 20% wider than the outer diameter of the measuring device 1. If it is a rigid body, the light irradiation unit 2 may break through the pipe W as shown by the dotted line, causing damage to the pipe or head 1, or the light irradiation unit 2 may stop at the pipe wall even if a force is applied from behind. On the other hand, if the elastic member 41 is present, the light irradiation unit 2 and the pipe W come into contact with each other and pressure is applied to the elastic member 41, but the elastic member 41 bends toward the back of the pipe to relieve the pressure, and the light irradiation unit 2 is inserted into the pipe W without being damaged. The effect (2) will be described later in "Considerations for ensuring the measurement range", and the effect (3) will be described later in "Improving the quality of the image of the camera 31".

[0039] The transparent window 43 is made of transparent resin or glass. Its shape is a cylinder or an N-sided prism (N is an integer) with two upper and lower planes as shown in FIG. 8, with a through hole for mounting the surface elastic member 41 located approximately in the center, and both end faces being flat and parallel within the machining accuracy range. The transparent window 43 has a thickness such that the elastic member 41 is inserted through the through hole of the transparent window 43 to position the elastic member 41 in the first direction Ax1, and the transparent window 43 must have a thickness capable of fixing the elastic member 41. As an example, when the outer diameter of the transparent window 43 is φ10 mm, the transparent window 43 has a cylindrical shape with a thickness of 1.5 mm and a through hole with a diameter of 2.6 mm. The outer size will be described later in the section "Considerations for ensuring the measurement range."

[0040] The transparent window 43 has a female screw in the center, into which the elastic member 41 is inserted and fixed. The transparent window 43 is also connected to the housing 33a. The connection between the housing 33a and the transparent window 43 will be explained below. At the front end of the housing 33a, there is a cylindrical cutout with an outer diameter of r0 and a thickness of d4, into which the transparent window 43 is inserted and fixed with a fixing part such as a set screw.

[0041] Three effects of the transparent window 43 will be described. Protection of the imaging unit 3 (1) A component that reduces obstructions and enables the camera 31 to capture light over a wide area (2) · Anti-multiple reflection (3) The three effects will be explained in detail. (1) It is a protection for the inside of the imaging unit 3. It is located in front of the housing 33a and functions as a lid for the housing 33a. (2) The only part through which light scattered at any position on the measurement target W passes before it reaches the camera 31 is the transparent tube 43, and the planes of the upper and lower end faces of only one transparent window are the interfaces, and there are no other interfaces. In comparison with the prior art, in Patent Document 1 (JP Patent Publication No. 2015-230301 A) and Patent Document 2 (JP Patent Publication No. 2021-113701 A), the structure corresponding to the transparent window is a cylindrical tube, and although there are two interfaces, they pass through a curved surface. Figure 13(a) shows the state of scattered light in the devices of Patent Document 1 and Patent Document 2, where beam1 or beam2 is a light trace. Figure 13(b) is a top view of the state of incident light b1, intruding light b2, and transmitted light b3 on the transparent window of beam1. If the transparent window were flat, the incident light b1 and the transmitted light b3 would be parallel. However, because the transparent window has curvature, the incident light and the transmitted light are not parallel, and the scattered light captures light rays with complex optical paths, which affects the calculation results in the product calculation process in product calculation unit 6, which will be described later. (3) will be described later in the section entitled "Improving the image quality of camera 31."

[0042] Cable 44 is a member made up of two or more bundled electric wires, which transmits power to light source 22. Two of the electric wires in cable 44 are connected to the positive terminal and ground terminal of light 21. Cable 44 is wired inside housing 33a, but the cable coating is stripped off at the end, and the electric wires are branched out. The electric wire portion is referred to as electric wire 45.

[0043] The cable 44 is connected to the + and ground terminals of the light 21, but since the connection is weak with solder, it is fixed by crimping or the like. The light 21 cable 44 further passes through the center of the elastic member 41 and the transparent window 43, enters the housing 33a, the cable is stripped of its coating and branches into electric wires, and the electric wire parts are referred to as electric wires 45. Each electric wire 45 passes through a different conductor 34 along the plane of the transparent window 43 and connects to the elastic member 35. The electric wires 45 connected to the + and ground terminals of the light 21 are connected to the + and ground wires of the cable 51 described later. The electric wires 45 are preferably arranged as shown in the wiring image diagram 7, and the electric wires 45 in the housing 33a are preferably wired in positions separate from each other. The electric wires 45 may be directly connected to a battery or a power outlet. They may also be connected to a controller that controls the frequency and voltage of the power supply.

[0044] The scanning unit 5 has a camera cable 51 (abbreviated as cable 51) connected to the first direction Ax1 of the camera 31 extending backward, and its tip is connected to the product calculation unit 6 and a power source described later. One example is an example of an insertion device in which an operator manually inserts the inner surface measurement head 1, but it may be attached to a robot or the like. The cable 51 is connected to the camera 31 and is a communication medium between the camera 31 and a computer, and is a general cable with a set standard, such as a USB cable, a camera link, or a LAN cable. In FIG. 1, the camera power supply is assumed to be bus power, but the power supply may be connected to an outlet. It may also be connected to a controller that controls the camera 31. The cable 51 is a bundle of electric wires, but materials such as optical fiber may also be used as long as they correspond to the bending radius of the measurement target. In this case, a lens is attached to the tip of an optical fiber bar inside the camera housing 33, and the camera 31 having an image receiving element is attached to the end of the optical fiber outside the camera housing 33.

[0045] The product calculation unit 6 is composed of a memory unit 61 that receives the image signal output from the head 1 and stores the received image signal, a calculation unit 62 including a CPU that extracts the luminance distribution of the pipe inner wall from the image signal recorded in the memory unit and calculates the shape of the pipe inner surface, and a display unit 63 that is a monitor. For example, the product calculation unit 6 is a PC, a tablet, a mobile phone, etc. In addition, the product calculation unit 6 is a component that has means for acquiring pipe inner surface shape data and calculating geometric information such as the pipe diameter (circle or ellipse) after receiving the image signal output from the head 1, and will be described later in the method of the present invention.

[0046] (Considerations for ensuring measurement range) Using FIG. 4 showing the layout of the basic components of head 1, it will be explained how the imaging field of camera 31 can be secured and head 1 itself does not affect the measurement by appropriately selecting the component layout or dimensions. The characters in Figure 4 will be explained below. f is the position on the z-axis of the lens center of camera 31 α1 is the half angle of the vertex of an isosceles triangle formed by a line passing through the yz plane of the fixture 42 and the vertex at the f. α2 is half the angle of view of the lens of camera 31. d1 is the distance between the point and the plane of the transparent window 43 in the negative direction of the first direction. d2 is the distance between f and the surface on the flat sheet PBM, and is the so-called object distance. d3 is the distance between the point and the plane on the end surface of the irradiation unit housing 23 in the negative direction of the first direction. D11 is half the length of fixture 42 in the y-axis direction D12 is the distance half the length of the base of an isosceles triangle with a vertex angle of 2×α 2 and height d 1. D21 is the distance half the length of the base of an isosceles triangle with a vertex angle of 2×α 1 and height d 2. D22 is the distance half the length of the base of an isosceles triangle with a vertex angle of 2×α 2 and height d 2. D3 is half the length of the base of an isosceles triangle with a vertex angle of 2×α 1 and height d 3. A A region that passes through the f and is equal to or smaller than an angle of α 1 with respect to the first direction Ax1

[0047] When measuring the inner surface of a pipe, head 1 is inserted into the pipe, but the inside of the pipe is generally hollow in the first direction Ax1 beyond head 1, and the wall surface of the pipe is present on the side. When an image is taken with camera 31 in this state, the pipe is generally captured on the periphery of the captured image, and there is no image of the pipe in the center of the image. Since the light irradiation unit 2 and the holding unit 4 are present in front of the camera 31, the head 1 itself is captured in the image, but the image of the head 1 is centered on the screen so that it does not overlap with the image of the pipe. The specific structure is to place the light irradiation unit 2 and the holding unit 4 in a specific area (area A). For this reason, when the camera 31 captures the image of the head 1 itself, the blurred fixing device 42 is captured in the approximate center of the image, but the light irradiation unit 2 and the holding unit 4 other than the electric wire 45 are not captured. Regarding the image of electric wire 45, electric wire 45 passes in front of camera 31, but since the focus of the condenser lens of camera 31 is on the flat sheet PBM which is d2 away from the lens center f, and electric wire 45 is d1 away from the lens center f, by configuring the depth of field to be (d2 - d1) / 2 or less, the image of electric wire 45 becomes blurred and its effect on measurement becomes small. The depth of field can be calculated from the lens specifications, or an actually measured value can be used.

[0048] Figure 11 shows an image taken with camera 31 after inserting head 1 into ring gauge RG as the measurement object and shining light from light irradiation unit 2 onto flat sheet PBM and camera illumination 37. Fixture 42, a hexagonal socket screw in the center, is captured in the image, while light irradiation unit 2 and holding unit 4 are hidden and cannot be seen. Also, it can be seen that there are three electric wires 45, located at 6 o'clock, 7 o'clock, and 9 o'clock from the center of the image, but the flat sheet PBM is clearly visible, and although the electric wires 45 are present, they have little effect on the measurement. The fact that the flat sheet PBM is clearly visible and does not affect the measurement will be discussed later in "Inner surface measurement method".

[0049] Next, the maximum measurement range D22 and the minimum measurement range D21 will be described. The maximum measurement range D22 is 2·d2·tan(α1) by making the diameter of the transparent window 45 larger than 2·d2·tan(α1). The minimum measurement range D21 is 2·d2·tan(α2), which corresponds to the diameter of the circle of the cross-section of the boundary of region A passing through the plane of the planar sheet PBM. Also, 2·D21 < D22 is necessary to ensure the measurement range. The dimensions of each component only need to fit within region A, such as the light irradiation 2 and the holding part 4. If D21 and D21 are set and the light irradiation 2 and the holding part 4 can be assembled within region A, the dimensions of each member of the light irradiation 2 and the holding part 4 can be freely determined.

[0050] (Regarding the improvement of the quality of the image of camera 31) Next, the head 1 has the following two effects for improving the quality of the image of the camera 31. · Structure with less optical distortion (1) · Countermeasure against multiple reflections (2) Next, (1) will be described. Compare with the previous inner surface measuring device (Patent Document 1). The previous inner surface measuring device is an inner surface measuring device that fixes the light irradiation part 2 and the imaging part 3 with a transparent cylindrical material GL and has the structure shown in FIG. 13. The scattered light from the measurement object W passes through the transparent cylindrical material GL with curvature. Referring to the enlarged view 13(b) of the light trace of the scattered light from the measurement object W passing through the transparent cylindrical material GL seen from the upper surface of GL, the incident light b1 of the scattered light from the measurement object W to the transparent window GL and the direction of the transmitted light exiting the transparent window GL are different. In the inner surface measuring head 1 of the present invention, the planar sheet PBM irradiated from the light irradiation part 2 has scattered light at the measurement object W incident on the camera 31, but the parts passing through the head 1 only have a transparent window 43 with parallel end faces. Therefore, since the angle between the incident light of the scattered light from the measurement object W on the transparent window 43 and the light exiting the transparent window 43 of the transmitted light is the same, the distortion correction becomes simpler.

[0051] Next, (2) prevention of multiple reflections will be explained. The head 1 of the present invention has two types of mechanisms for preventing multiple reflections. First, the first method for preventing multiple reflections will be explained. It will be explained that the structure of the light irradiation unit 2 has the effect of removing or reducing the cause of deterioration of the quality of the image captured by the camera 31, such as multiple reflections. The prior art inner surface measuring device (see FIG. 13) has a structure different from the transparent window 43 when fixing the reflecting member 21 or the light source 22, and as shown in FIG. 13, the camera housing 33 and the transparent cylinder GL are connected, and the tip is connected to the irradiation unit housing housing 23 that houses the reflecting member 21 or the light source 22. When the image of the camera 31 is captured using this device, the scattered light at point P1 may be reflected inside the transparent body, resulting in a ghost image due to the light reaching the camera 31 through multiple paths. The ghost image here refers to the scattered light being further reflected before reaching the camera 31, and some image appears in the camera image at a position that does not actually exist. 13, it is desired that only scattered light beam1 reaches camera 31, but scattered light beam2 also reaches camera 31, and this scattered light beam2 causes a ghost image. This is because the reflective surface of the transparent cylinder GL is perpendicular to the optical axis of camera 31, and the reflected light heads toward camera 31. In the arrangement of transparent window 43 of the present invention, the normal to the surface of transparent window 43 is nearly parallel to the first direction Ax1, and when a light ray in the negative direction of the z axis of incident light is reflected by the surface of transparent window 43, it is deflected toward the positive direction of the z axis, so that the reflected light does not enter camera 31 and multiple reflections are prevented.

[0052] Next, the second measure to prevent multiple reflections will be described. This is a measure to prevent multiple reflections that occur when the measurement target W is close to a mirror surface. Figure 12 shows an example in which the measurement device 1 is inserted into the inner surface of the measurement target W and a flat beam is irradiated, and the beam is split into two directions at point P on W and reaches the camera 31 (a) a top view and (b) a side view. Although it is desired to observe only beam1 with the camera 31, since the measurement target W is close to a mirror surface, beam2 reflected at point P2 also reaches the camera 31. The light beam from point P takes multiple routes, so-called ghost images, and the quality of the image is reduced. As a measure to prevent this, if a "light-absorbing obstacle" is placed in the path of beam2, beam2 will disappear before reaching the camera 31, and the ghost image will disappear. A specific method of the present invention is to place an elastic member 41 as a light-absorbing obstacle.

[0053] (Inner surface measurement method) An apparatus used in the measurement method of the present invention is an inner surface measuring apparatus 1100, Fig. 14 is a block diagram explaining the inner surface shape measuring apparatus according to this embodiment, and Fig. 15 is a flow chart explaining the inner surface shape measuring method according to this embodiment. The inner surface shape measuring method described below is merely one example, and is not limited to this configuration and can be modified as appropriate.

[0054] After the head 1 moving step ST101, there is a straight pipe determination step ST102, in which it is determined whether the image capture location is on a straight pipe or a curved pipe. The camera lighting 37 provided in the image capture unit 3 illuminates the entire inside of the pipe, and the image capture unit 3 captures an image. If the image of the head 1 at the center of the image includes the head 1 itself, it is determined that the head 1 is on a curved pipe because the holding part is bent. If it is on a curved pipe, the process returns to the head 1 moving step ST101.

[0055] After the straight pipe determination step ST102, in the planar beam irradiation step ST103, the camera illumination 37 is turned off, and the light irradiation unit 2 is caused to irradiate the measurement target W with the light sheet PBM.

[0056] In the photographing step ST104 after the planar beam irradiation step 103, the imager 3 photographs the scattered light on the measurement target W. For example, in the case of the inside of a pipe, an approximately circular image as shown in FIG. 10 is obtained.

[0057] In the image distortion correction step ST106 following the photographing step ST105, a process of correcting distortion of the photographed image is carried out by the calculation unit 6 for measuring the pipe inner surface shape. The image plane is a two-dimensional arrangement of light receiving elements such as CCD or CMOS at approximately equal intervals, but the object plane corresponding to the light receiving elements is not at equal intervals due to distortion caused by lenses, etc. This step is a step in which the object plane is also arranged at approximately equal intervals like the image plane, and an image in which the image of the object plane is arranged in two dimensions at intervals of t0 is realized by rearranging the two-dimensional data string with reference to a distortion correction table.

[0058] In the product calculation step ST107 following the image distortion correction step ST106, the coordinates of the light trace on the pipe are calculated, and the inner diameter of the pipe is calculated from the data group of the calculated coordinates. This step is performed by the calculation unit 61 for measuring the shape of the inner surface of the pipe. The simplest method of calculating the coordinates will be described. The image obtained in ST106 is a light trace image on the intersection line between the flat light ray and the pipe surface from which the distortion has been removed. If the center of the image is the origin, the horizontal right direction of the image is the X-axis, and the vertical direction is the Y-axis, the coordinate calculation takes out the brightness data string of the image at an angle of Θ degrees from the center of the image to the X-axis direction, obtains the position r0 at which the brightness distribution of the data string is at its peak, and expresses it in polar coordinates as (Θ, r0×0). For example, Θ is performed in 1-degree increments from 0 degrees to 360 degrees to obtain a total of 360 coordinate values. In this way, the coordinate values ​​of one cross section of the pipe are obtained. The position r0 where the peak is obtained using the luminance distribution, and even if the electric wire 45 in Figure 11 is blurred, the intensity of the luminance distribution shape will only be reduced, so the peak position r0 is obtained and ellipse fitting is performed. A general software program library can be used for ellipse fitting, and the obtained minor axis is taken as the diameter of the pipe. The obtained pipe diameter or the coordinate values ​​of the pipe inner surface are saved in memory as an electronic file in a format that can be read by CAD or in ASCII format, or displayed on the display unit.

[0059] To check the accuracy of the device, we recommend checking whether there are any changes in the measurement values ​​of a standard tool such as a ring gauge before and / or after the work. If the measurement value of the standard tool deviates from the value of the standard tool, the deviation can be used as a correction amount and incorporated into the device. If the repeated measurements of the standard tool do not meet the device specifications, we recommend replacing the inner surface measuring head 1.

[0060] Second embodiment The configuration diagram of the second embodiment seen from the front is shown in Fig. 16. The configuration is based on the first embodiment, and the inner surface measuring device head 120 is for measuring the inner surface shape of a pipe reinforced to prevent multiple reflections, and the inner surface measuring device 1200 is equipped with a product calculation unit and a display unit similar to those of the first embodiment. The difference from the first embodiment is that the inner surface measuring method is the same, but the shape of the elastic member is a cone-shaped elastic member having a substantially conical shape whose diameter increases in the first direction, as shown in the elastic member 41-2 in Fig. 16. The shape of the elastic member is located just between the light irradiation unit 2 and the imaging unit 3 in Fig. 4, and is close to the area A, and is arranged as much as possible over the entire range between the fixing device 42 and the irradiation unit housing, which is hidden and cannot be imaged by the camera 31.

[0061] The mechanism of blocking multiple reflections by inserting it into the path of the multiple reflections is the same as in the first embodiment, and the larger the volume of the obstacle placed, the stronger the prevention of multiple reflections, and the shape that is larger than the cylindrical shape of the first embodiment and has the maximum volume that does not affect the imaging of the camera 31 is close to the shape of the area A. The example in Figure 17 is an example in which multiple reflections cannot be prevented for the light beam to point P1 by the inner surface measuring head 1 of the first embodiment, but multiple reflections are reduced in the second embodiment by increasing the volume of the obstacle.

[0062] Third embodiment Fig. 18(a) is a configuration diagram seen from the front of the third embodiment, and the configuration is based on the first embodiment, and the head 130 for the inner surface measuring device is for measuring the inner surface shape of a pipe using a reinforcing member 41-3 having a function of strengthening the restoring force of the elastic member 41 of the first embodiment and substituting for wiring, and the inner surface measuring device 1300 is equipped with a product calculation unit and a display unit similar to those of the first embodiment. Fig. 18(b) is a cross-sectional view taken along the line XVIII-XVIII passing through the surface of the irradiation unit housing 23b. Next, differences in the mechanical configuration from the first embodiment will be described. The cable 44 is eliminated, and instead, two electric wires 48 are used and connected to the power supply terminals of the lighting 21. The elastic member 41 is eliminated, and an elastic member 46-1 and a reinforcing member 46-2 are used. The elastic member 46-1 is made of a conductive material and is configured using two elastic members having the same outer diameter, overall length, and elastic structure, with its front end connected to the electric wire 48 and its rear end connected to the electric wire 45. The reinforcing member 46-2 is configured, for example, using one or more elastic members having the same shape as the elastic member 41-3 but without electric wires or the like. The elastic member 46-1 and the reinforcing member 46-2 are fixed to the irradiation unit housing 33b-3 and the transparent window 43-3 with screws or the like, but the fixing position must be at approximately the center of the irradiation unit housing 33b-3 and the transparent window 43-3, and must be circumscribed on a circle with a distance of D'11 (=0.5 x d1 x tan(0.5 x α2)) or less, or must be inside the circle (see FIG. 18(b)). The diameter of the female screw or the like of the irradiation unit housing 33b-3 and the transparent window 43-3 or the outer diameter of the elastic member 41-3 and the elastic member 41-4 must satisfy this condition. (See the definitions of d1 and α2 in the first embodiment.) Since the number of elastic members 46-1 and reinforcing members 46-2 is increased and the outer diameter of the part is narrowed, the stress applied to the transparent window from the elastic members and reinforcing members during bending is weakly distributed compared to the elastic member 41, so the transparent window 43-3 can be made thinner, and an example of this will be described below. In the first embodiment, the transparent window 41 made of acrylic material with an outer diameter of 10 mm has one through hole with a diameter of 2.6 mm in a cylinder with a thickness of 1.5 mm, but in the case of a transparent window 43 made of acrylic material with an outer diameter of 10 mm, the outer diameter of three through holes in a cylinder with a thickness of 1.0 mm can be φ0.6 to 0.8 mm. The inner surface measurement method is the same as in the first embodiment.

[0063] The effects of the third embodiment are as follows. - Reinforcement of the elastic part and the transparent window by holding them with an elastic member, a reinforcing member, and multiple elastic members - The wiring does not pass through an elastic material, and the power supply wire does not bend, reducing the risk of failure such as wire breakage.

[0064] (Fourth embodiment) The configuration of the inner surface measuring device 1400 is the same as that of the first embodiment except for the irradiation unit 2 and the calculation unit 6, and is an inner surface measuring device having an inner surface measuring head 140 (hereinafter abbreviated as 140), an operation unit, a calculation unit, and a display unit. A configuration diagram of the fourth embodiment as viewed from the front is shown in FIG. 19, and the configuration is that the irradiation unit 240, which replaces the light irradiation unit 2 of the first embodiment, is a component that irradiates a cone-shaped light beam (hereinafter referred to as a cone beam CBM), and enables measurement of an overhang such as a protrusion inside a pipe. The difference in structure from the first embodiment is that in the shape of the reflection member 21, the light reflection surface of the mirror part is 45 degrees with respect to the first direction in the first embodiment, but the reflection member 21-1 is characterized by having an angle in the range of more than 45 degrees and not more than 60 degrees, and the part in which the reflection surface of 21a in FIG. 5 is changed to the above angle is 21c in FIG. 5, and the part in which the reflection surface of 21b in FIG. 5 is changed to the above angle is 21c in FIG. 5. Also, a part with a cone inner surface as the reflection surface may be used, as in 21e. Furthermore, the light source 22 may be a laser installed outside the inner surface measurement head, and may be reflected by a reflecting surface via an optical fiber to irradiate a conical beam CBM, in which case the wiring 44 and the electric wire 45 may be replaced with an optical fiber having a lens capable of irradiating collimated light, and the optical fiber may pass through the elastic member 41 from inside the irradiation unit housing, enter the camera housing, and then pass through a connector or hole to connect to an external light source. The optical fiber is fixed inside the irradiation unit housing with a fixing member from outside the illumination unit housing, but the position of the lens capable of irradiating collimated light is set as the light emission position E1, and the alignment and fixing are the same as for the light source 22 in the first embodiment. The photographing unit and the holding unit are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0065] Next, a mechanism that enables measurement inside a pipe with an overhang will be explained using Figure 20. This is an example where the camera 31 cannot capture an image with the flat sheet PBM, but can capture an image with the cone beam CBM. As shown in Figure 20(a), there is a pipe on the line connecting the camera and point P1 irradiated on the pipe W from the flat sheet PBM, so the pipe itself becomes an obstacle and the camera 31 cannot capture an image. On the other hand, as shown in Figure 20(b), there is no obstacle on the line connecting the camera 31 and point P1 irradiated on the pipe W from the cone beam CBM, so measurement is possible. When the mirror reflecting surface is larger than 45 degrees, the z coordinate of point P1 is in the negative direction compared to 45 degrees, and the scattering angle at point P1 becomes narrower, making it easier to avoid obstacles such as overhangs.

[0066] (Inner surface measurement method) The flow chart of the inner surface measurement method of the fourth embodiment is shown in FIG. 21. Since the method is the same as the method of the first embodiment except that the product calculation step ST107 is replaced with the product calculation step ST117, only the product calculation step ST117 will be described. ST117 is performed after the image distortion correction step ST106. In the image distortion correction step ST106, a light trail image on the intersection line between the cone-shaped light ray and the pipe surface from which distortion has been removed is obtained, and the center of the image is described as the origin, the horizontal right direction of the image is the X-axis, and the vertical direction is the Y-axis. The product calculation includes coordinate calculation and pipe diameter calculation. The coordinate calculation will be described. The brightness data string of the image in the Θ degree angle direction with respect to the X-axis direction from the image center is extracted, and the position r0 at which the brightness distribution of the data string is at its peak is obtained. When expressed in a cylindrical coordinate system, it becomes (Θ, r0×t0, r×r0×t0). Unlike the first embodiment, the cone uses a solid beam, so the coordinate values ​​become a data string expressed in a three-dimensional coordinate system. For example, Θ is scanned from 0 degrees to 360 degrees in 1 degree increments to obtain a total of 360 coordinate values. In this way, the coordinate values ​​of one cross section of the inner surface of the pipe are obtained. In addition, the pipe diameter calculation is performed by adding plane fitting of one cross-section data string to the pre-processing of ellipse fitting. The plane fitting algorithm is widely used and will not be described. If the shape of the inner pipe surface is cylindrical, the distance between the plane fitted and each coordinate value of one cross-section of the inner pipe surface falls within a certain range. Therefore, if the variance of the distance of each point from the plane is within the precision of the device specifications, the inner pipe surface is determined to be cylindrical, and the process proceeds to ellipse fitting to calculate the diameter. The method of calculating the pipe diameter from ellipse fitting is the same as in the first embodiment. The obtained pipe diameter or the coordinate value of the inner pipe surface is stored in memory as an electronic file in a format readable by CAD or ASCII format, or is displayed on the display unit. [Explanation of symbols]

[0067] 1, 120, 130, 140 Head for inner surface measuring device 2. Light irradiation unit 21 Reflective material 21-1 Reflective material 22 Light source 23, 23a, 23b, 23b-3 Irradiation unit housing 28 Protective Materials 3. Imaging unit 31 Camera 33, 33a, 33b Camera housing 34 Conductor 37 Camera Lighting 4 Holding part 41, 41-2, 46-1 Elastic member 42 Fixtures 43, 43-3 Transparent window 44 Cable 45 Electric wire 46-2 Reinforcement members 5 Control section 6 Product Calculation Department 61 Storage section 62 Arithmetic section 63 Display section 1100, 1200, 1300, 1400 Internal surface measurement device

Claims

1. A head for an inner surface measuring device for measuring an inner surface shape of a pipe, comprising: a light irradiation unit for irradiating an inner surface of the pipe with a planar light beam; an imaging unit having a camera for receiving scattered light from the inner surface of the pipe; and a holding unit disposed between the light irradiation unit and the imaging unit for connecting the light irradiation unit and the imaging unit; A head for an inner surface measuring device, characterized in that the imaging unit, the holding unit, and the light irradiation unit are arranged in order in a first direction, and the holding unit is configured to be freely bent.

2. 2. The head for an inner surface measuring device according to claim 1, further comprising an imaging unit housing for accommodating the camera, the imaging unit housing having a window portion on a front side through which the scattered light can pass, and the holding portion being attached and fixed to approximately the center of the window portion.

3. 2. The head for an inner surface measuring device according to claim 1, wherein the holding portion includes a pipe-shaped elastic member and has a generally conical shape whose diameter increases as it extends in the first direction from the imaging portion toward the light irradiation portion.

4. 2. The head for an inner surface measuring device according to claim 1, wherein the light irradiation unit has a light emitting element that emits light in the first direction, and a mirror unit that receives the light emitted from the light emitting element and reflects the light in a planar form, and a light reflecting surface of the mirror unit has an angle in the range of 45 degrees or more and 60 degrees or less with respect to the first direction.

5. 5. The head for an inner surface measuring device according to claim 4, wherein the camera has a lens, and an object distance of the lens is approximately equal to a distance from the lens to the mirror portion.

6. An inner surface measuring device comprising: a head for an inner surface measuring device according to any one of claims 1 to 5; a memory unit for receiving an image signal output from the head for the inner surface measuring device and storing the received image signal; a calculation unit for extracting a luminance distribution of the inner wall of a pipe from the image signal stored in the memory unit and measuring the shape of the inner surface of the pipe; and a display unit for outputting measurement values ​​from the calculation unit to the outside. Surface measuring device.

Images