Lens unit for hole inspection

Abstract

The invention relates to a lens unit for hole inspection, which is used for shooting the interior of a hole of a workpiece by using a camera while ensuring uniform illuminance in the hole, reducing the noise of the shot image, and well removing foreign matters in the hole. The lens unit for hole inspection comprises: a cylindrical light guide tube which is surrounded by the tip of an outer tube and supported by one of the outer peripheral surface of an inner tube and the inner peripheral surface of the outer tube so as to surround the tip of the inner tube, and which diffuses and irradiates light emitted from a plurality of bullet-shaped light-emitting diodes on the mounting part side into a hole; an annular spacer having a plurality of gas passages and disposed between the light guide tube and the other of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube such that the plurality of gas passages extend along the light guide tube; and an annular gas passage which is divided between the outer peripheral surface of the light guide tube and the inner peripheral surface of the outer tube or between the inner peripheral surface of the light guide tube and the outer peripheral surface of the inner tube, communicates with the plurality of gas passages, and is opened at the top ends of the outer tube and the inner tube.

Description

Technical Field

[0001] The present disclosure relates to a hole inspection lens unit for inspecting the inside of a hole formed in a workpiece. Background Art

[0002] In the past, a hole defect detection device for inspecting the inside of a hole formed in a circuit substrate is known (for example, refer to Patent Document 1). The hole defect detection device includes: a cylindrical housing; a rod-shaped reflector inserted into the inside of the housing; an objective lens arranged on the protective glass side of the rod-shaped reflector; and a connecting sleeve that supports the base end of the housing and the rod-shaped reflector and is equipped with a CCD camera. In addition, an infrared light source processor and a collimating lens composed of a fixing plate are arranged between the outer peripheral side of the objective lens and the inner peripheral side of the housing. The collimating lens is surrounded by the top end of the housing on the protective glass side of the infrared light source processor and surrounds the objective lens.

[0003] In addition, in the past, there is a known inspection method, which inserts an insertion shaft with a wide-angle lens at the top into the interior of a hole, and inspects the wall surface of the hole based on the image transmitted through the wide-angle lens (for example, refer to patent document 2). In this inspection method, when inspecting the wall surface of the hole, gas is sprayed toward the depth of the hole along the outer peripheral surface of the insertion shaft. In this way, foreign matter such as water droplets and chips attached to the wall surface of the hole can be removed. In addition, as such an inspection method, the following method is also known: when inspecting the wall surface of the hole, a first gas is sprayed toward the depth of the hole along the outer peripheral surface of the insertion shaft, and around the first gas, a second gas with a higher flow rate than the first gas is sprayed in the same direction as the first gas (for example, refer to patent document 3).

[0004] Patent Document 1: Chinese Patent Application Publication No. 110823924

[0005] Patent Document 2: Japanese Patent Application Publication No. 2013-088136

[0006] Patent Document 3: Japanese Patent Application Publication No. 2015-049044

[0007] In the hole defect detection device described in Patent Document 1, light from an infrared light source processor is irradiated to the inside of the hole via a collimating lens having the property of transmitting light directly in a specific direction. Therefore, when the hole defect detection device of Patent Document 1 is used, uniform illumination cannot be ensured inside the hole to be the object, and the noise of the image captured by the CCD camera may increase. On the other hand, in the case where foreign matter such as water droplets exists inside the hole, it is preferable to spray gas into the hole to remove the foreign matter as described in Patent Documents 2 and 3. However, in the hole defect detection device of Patent Document 1, even if gas is sprayed along the outer peripheral surface of the housing, it may not be possible to remove foreign matter well from the wall surface of the hole, etc. Summary of the invention

[0008] Therefore, the main object of the present disclosure is to provide a hole inspection lens unit that can ensure uniform illumination inside the hole and reduce noise in the captured image when photographing the inside of the hole of a workpiece using a camera, and can effectively remove foreign matter existing inside the hole.

[0009] The hole inspection lens unit disclosed in the present invention is a hole inspection lens unit for inspecting the inside of a hole formed in a workpiece, and includes: a cylindrical outer tube; a cylindrical inner tube inserted into the inside of the outer tube; an objective lens arranged in the top end of the inner tube; a mounting portion supporting the base end of the outer tube and the base end of the inner tube, and having a camera mounted thereon for photographing the inside of the hole via the objective lens; a plurality of bullet-shaped light emitting diodes arranged in the inside of the outer tube and located around the inner tube; a cylindrical light guide tube surrounded by the top end of the outer tube and supported by one of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube in a manner surrounding the top end of the inner tube , so that the light emitted from the plurality of bullet-shaped light-emitting diodes on the mounting portion side is diffused and irradiated to the inside of the hole; an annular spacer having a plurality of gas passages, and arranged between the other of the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube and the light guide tube in a manner that the plurality of gas passages extend along the light guide tube; and an annular gas passage is divided between the inner circumferential surface of the outer tube and the outer circumferential surface of the light guide tube, or between the outer circumferential surface of the inner tube and the inner circumferential surface of the light guide tube, is connected to the plurality of gas passages of the spacer, and is opened at the top ends of the outer tube and the inner tube.

[0010] When the hole inspection lens unit of the present invention is used to photograph the inside of the hole formed in the workpiece with a camera, the hole inspection lens unit with the camera mounted on the mounting portion is made to be stationary in a manner that the objective lens is located above the hole. In addition, each bullet-shaped light emitting diode is made to emit light. The bullet-shaped light emitting diode has excellent light-gathering properties, and the light emitted from each bullet-shaped light emitting diode is diffused into the inside of the hole by a cylindrical light guide and irradiated. Thus, when the inside of the hole of the workpiece is photographed with a camera, uniform illumination can be ensured inside the hole, and the noise of the image photographed by the camera can be reduced. In addition, in the hole inspection lens unit of the present invention, the light guide is surrounded by the top end of the outer tube, and is supported by one of the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube in a manner that surrounds the top end of the inner tube. In addition, an annular spacer having a plurality of gas passages is arranged between the other of the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube and the light guide, and the plurality of gas passages of the spacer extend along the light guide. Furthermore, between the outer circumference of the light guide tube and the inner circumference of the outer tube, or between the inner circumference of the light guide tube and the outer circumference of the inner tube, an annular gas passage is defined, which is connected to the plurality of gas passages of the spacer and is open at the top of the outer tube and the inner tube. Thus, when the inside of the hole of the workpiece is photographed by a camera, gas is supplied to the annular gas passage via the plurality of gas passages of the spacer, so that the gas can be ejected from between the outer tube and the inner tube to the inside of the hole. As a result, compared with the case where the gas is ejected from the outer circumference of the outer tube to the hole, foreign matter can be suppressed from adhering to the objective lens, and foreign matter present in the inside of the hole can be well removed. In addition, in the hole inspection lens unit disclosed in the present invention, the gas supplied to the annular gas passage is rectified by the plurality of gas passages of the spacer, and the flow rate of the gas ejected from the annular gas passage toward the hole can be increased by adjusting the passage cross-sectional area of ​​the plurality of gas passages. Therefore, according to the hole inspection lens unit of the present disclosure, when the inside of the hole of the workpiece is photographed by a camera, uniform illumination can be ensured inside the hole, noise of the photographed image can be reduced, and foreign matter existing inside the hole can be removed satisfactorily. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram showing the configuration of a hole inspection system to which the hole inspection lens unit of the present disclosure is applied.

[0012] Figure 2 It is a longitudinal sectional view showing the hole inspection lens unit of the present disclosure.

[0013] Figure 3 It is an enlarged cross-sectional view showing a main part of the hole inspection lens unit of the present disclosure.

[0014] Figure 4 It is a perspective view showing the main part of the hole inspection lens unit of the present disclosure.

[0015] Figure 5 This is an enlarged cross-sectional view showing a main part of another hole inspection lens unit disclosed in the present invention.

[0016] Description of Reference Numerals

[0017] 1: Hole inspection system;

[0018] 10: Shooting tools;

[0019] 20, 20B: lens unit;

[0020] 21: external tube;

[0021] 21is, 21ts, 27is: inner surface;

[0022] 21t: apical part;

[0023] 22: inner tube;

[0024] 22os, 27os: outer surface;

[0025] 23: objective lens;

[0026] 23w: wide-angle lens;

[0027] 27, 27B: light guide tube;

[0028] 28, 28B: annular gas passage;

[0029] 29, 29B: spacer;

[0030] 29p: gas passage;

[0031] 30: Bullet-shaped light-emitting diode;

[0032] 31: Substrate;

[0033] 40: air supply device;

[0034] 50: Camera;

[0035] W: workpiece. DETAILED DESCRIPTION

[0036] Next, a mode for carrying out the invention disclosed herein will be described with reference to the drawings.

[0037] Figure 1 1 is a schematic diagram showing the configuration of a hole inspection system 1 to which a hole inspection lens unit (hereinafter, simply referred to as “lens unit”) 20 of the present disclosure is applied. Figure 1The hole inspection system 1 shown is used to inspect the inside (inner wall surface, bottom surface, etc.) of a hole H formed in a workpiece W such as a transmission housing. The hole H to be inspected may be a round hole or a square hole, a threaded hole or a non-threaded hole, a through hole or a non-through hole. In addition, the workpiece W is not limited to the transmission housing.

[0038] like Figure 1 As shown, the hole inspection system 1 includes a system control device 2, a plurality of robots 3, a plurality of robot control devices 4 respectively connected to the system control device 2 and controlling the corresponding robots 3, and an inspection processing device 5 connected to the system control device 2. The system control device 2 includes a computer having a CPU, ROM, RAM, etc., exchanges signals (information) with the plurality of robot control devices 4 and the inspection processing device 5, and uniformly controls the hole inspection system 1. Each robot 3 is a robot arm capable of holding and moving a photographing tool 10 including a lens unit 20 and a camera 50. In addition, each robot control device 4 includes a computer having a CPU, ROM, RAM, etc., and controls the corresponding robot 3 according to a predetermined control sequence so that the photographing tool 10 moves to an inspection operation position above a predetermined distance from the object, i.e., the hole H.

[0039] The inspection processing device 5 is a computer having a CPU, ROM, RAM, etc. The inspection processing device 5 is connected to a camera 50 of the imaging tool 10 via a connector, a cable, etc. provided on the robot 3. In addition, an inspection program for inspecting the state of the inside of the hole H based on the image (image data) of the inside of the hole H photographed by the camera 50 is installed in the inspection processing device 5. The inspection program (software) cooperates with the hardware such as the CPU, ROM, and RAM of the inspection processing device 5, and implements, for example, a neural network for determining (diagnosing) whether the state of the inside of the hole H is good or not based on the image photographed by the camera 50.

[0040] Figure 2 2 is a longitudinal sectional view showing the lens unit 20. Figure 2 As shown, the lens unit 20 includes an outer tube 21, an inner tube 22, an objective lens portion 23, a plurality of relay lenses 24, a mounting portion 25 for mounting the camera 50, a retainer 26, a light guide 27, and a plurality of (for example, 6 in this embodiment) bullet-shaped light emitting diodes 30.

[0041] The outer tube 21 is formed into a cylindrical shape by a material having light-shielding properties such as metal, and the top end 21t of the outer tube 21 is formed into a tapered shape. In addition, the inner diameter Id1 of the top end 21t of the outer tube 21 is smaller than the inner diameter Id0 of the portion on the side of the mounting portion 25 of the outer tube 21. The inner tube 22 is formed into a cylindrical shape having an outer diameter smaller than the inner diameter of the outer tube 21 by a material having light-shielding properties such as metal. In the present embodiment, the inner tube 22 is formed of stainless steel, and a black oxide film or a black plating layer (black chrome plating) formed by an electrolytic coloring method is applied to the inner circumferential surface 22is of the inner tube 22. The inner tube 22 is coaxially inserted into the interior of the outer tube 21, and is fixed to the base end of the outer tube 21 via a retainer 26.

[0042] The objective lens section 23 includes a wide-angle lens 23w, which is disposed (fixed) in the top end of the inner tube 22. A plurality of relay lenses 24 are disposed in the inner tube 22 at regular intervals so that the image from the wide-angle lens 23w is relayed to the camera 50 mounted on the mounting section 25. Thus, the entire interior of the hole H can be focused. In addition, by disposing a plurality of relay lenses 24 in the inner tube 22, the axial length of the lens unit 20 can be determined according to the shape of the workpiece W, for example, the axial length of the lens unit 20 for photographing the interior of the hole H formed at the bottom of the workpiece W can be increased. Furthermore, depending on the axial length required for the lens unit 20, a single relay lens 24 can be disposed in the inner tube 22, or the relay lens 24 can be omitted.

[0043] The mounting portion 25 is fixed to the holder 26, and the base end of the outer tube 21 and the base end of the inner tube 22 are supported via the holder 26. In addition, an external thread 25t of the C-mount standard is formed on the outer peripheral surface of the mounting portion 25. Thus, various industrial cameras conforming to the C-mount standard and having different specifications such as the number of pixels can be mounted on the mounting portion 25. In addition, an industrial camera conforming to the CS-mount standard can also be mounted on the mounting portion 25 via an adapter.

[0044] The light guide tube 27 is formed of glass, quartz or the like into a cylindrical shape shorter than the outer tube 21 or the like. The light guide tube 27 has an outer diameter Od1 that is smaller than the inner diameter Id1 of the tip portion 21t of the outer tube 21 and an inner diameter that is slightly larger than the outer diameter of the inner tube 22, and the tip portion of the inner tube 22 is coaxially fitted inside the light guide tube 27. Thus, the light guide tube 27 is coaxially supported by the outer peripheral surface of the inner tube 22, surrounds the tip portion of the inner tube 22, and is surrounded by the tip portion 21t of the outer tube 21 via an annular space. That is, between the inner peripheral surface 21ts of the tip portion 21t of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27, an internal space on the side of the mounting portion 25 of the outer tube 21 and an annular gas passage 28 that opens at the tips of the outer tube 21, the inner tube 22, and the light guide tube 27 are divided.

[0045] In addition, the end of the light guide tube 27 on the side of the mounting portion 25 protrudes from the inside of the tip portion 21t into the internal space on the side of the mounting portion 25 of the outer tube 21, and an annular spacer 29 is arranged between the inner peripheral surface 21is of the outer tube 21 and the end of the light guide tube 27 on the side of the mounting portion 25. That is, the spacer 29 is coaxially fitted into the internal space on the side of the mounting portion 25 of the outer tube 21, and the end of the light guide tube 27 on the side of the mounting portion 25 is coaxially fitted into the inner hole of the spacer 29. Thus, the light guide tube 27 is coaxially held by the outer tube 21 and the inner tube 22 via the spacer 29.

[0046] In addition, the spacer 29 has a plurality of gas passages 29p arranged at intervals (e.g., equal intervals) in the circumferential direction. In the present embodiment, each gas passage 29p is a circular hole extending in the axial direction of the spacer 29. However, the gas passage 29p may be, for example, a recess (cutout) formed on the inner circumferential surface of the spacer 29. When the spacer 29 is disposed between the outer tube 21 and the light guide 27, each gas passage 29p extends in the axial direction of the lens unit 20 along the outer tube 21, the inner tube 22, and the light guide 27, and is connected to the annular gas passage 28 between the top end 21t of the outer tube 21 and the light guide 27.

[0047] A plurality of bullet-shaped light emitting diodes 30 are arranged inside the outer tube 21 and around the inner tube 22 at intervals (e.g., at equal intervals) in such a manner that the ends of the mounting portion 25 of the spacer 29 and the mounting portion 25 of the light guide tube 27 are opposed (contacted) to each other. In addition, the terminals of each bullet-shaped light emitting diode 30 are connected to a ring-shaped substrate 31, thereby connecting the plurality of bullet-shaped light emitting diodes 30 in series or in parallel. The substrate 31 is arranged on the mounting portion 25 side of the light emitting portion of the plurality of bullet-shaped light emitting diodes 30, and a cable (not shown) for supplying power to each bullet-shaped light emitting diode 30 is connected to the substrate 31. The cable is led out to the outside of the outer tube 21 through the space between the outer tube 21 and the inner tube 22 and the cable lead-out portion 21c formed on the outer tube 21, and is connected to a lighting power source (not shown) through a connector.

[0048] In addition, an air pipe joint 35 is connected to the outer tube 21 between the mounting portion 25 and the base plate 31 in the axial direction so as to communicate with the space between the outer tube 21 and the inner tube 22. The air pipe joint 35 is connected to an air supply device 40 through an air hose or the like. The air supply device 40 is controlled by, for example, the system control device 2. By operating the air supply device 40, air can be supplied from the air pipe joint 35 to the space between the outer tube 21 and the inner tube 22.

[0049] When the camera 50 is used to photograph the inside of the hole H formed in the workpiece W using the lens unit 20 constructed as described above, the robot 3 is used to move the photographing tool 10, i.e., the lens unit 20 on which the camera 50 is mounted on the mounting portion 25, so that the objective lens portion 23 (wide-angle lens 23w) is located above the hole H at a predetermined distance, and the lens unit 20 is stationary at the inspection operation position. Furthermore, each bullet-shaped light emitting diode 30 is made to emit light. The bullet-shaped light emitting diode 30 has excellent light-gathering properties, and the light emitted from each bullet-shaped light emitting diode 30 is diffused into the inside of the hole H by the cylindrical light guide 27 and irradiated. Thus, when the camera 50 is used to photograph the inside of the hole H of the workpiece W, uniform illumination can be ensured inside the hole H, and noise such as light streaks in the image photographed by the camera 50 can be extremely well reduced.

[0050] In the lens unit 20, the light guide tube 27 is surrounded by the top end portion 21t of the outer tube 21 and supported by the outer peripheral surface of the inner tube 22 in such a manner as to surround the top end portion of the inner tube 22. In addition, an annular spacer 29 having a plurality of gas passages 29p is arranged between the inner peripheral surface 21is of the outer tube 21 and the light guide tube 27, and the plurality of gas passages 29p of the spacer 29 extend along the light guide tube 27 and the like. Furthermore, an annular gas passage 28 is defined between the inner peripheral surface 21ts of the top end portion 21t of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27, and the annular gas passage 28 is communicated with the plurality of gas passages 29p of the spacer 29 and opens at the top ends of the outer tube 21, the inner tube 22, and the light guide tube 27.

[0051] Thus, when the camera 50 is used to photograph the interior of the hole H of the workpiece W, by operating the air supply device 40, as shown in FIG. Figure 4 As shown by the dotted line in FIG, air can be supplied from the air pipe joint 35 to the annular gas passage 28 via the space between the outer tube 21 and the inner tube 22, the gap between the inner hole of the substrate 31 and the inner tube 22, the gap between the plurality of bullet-shaped light-emitting diodes 30 and the inner tube 22, and the plurality of gas passages 29p of the spacer 29, and the air can be ejected from between the outer tube 21 and the inner tube 22 to the inside of the hole H. As a result, compared with the case where air is ejected from the outer periphery of the outer tube 21 to the hole H, foreign matter can be suppressed from being attached to the objective lens portion 23 (wide-angle lens 23w), and foreign matter such as water droplets (cleaning liquid) and cuttings existing inside the hole H can be removed well.

[0052] Furthermore, in the lens unit 20, the air supplied to the annular gas passage 28 is rectified by the plurality of gas passages 29p of the spacer 29, and the passage cross-sectional area (opening area) of the plurality of gas passages 29p is adjusted, so that the flow rate of the air ejected from the annular gas passage 28 toward the hole H can be increased. Therefore, according to the lens unit 20, when the inside of the hole H of the workpiece W is photographed by the camera 50, uniform illumination can be ensured inside the hole H and noise of the photographed image can be reduced, and foreign matter existing inside the hole H can be removed well.

[0053] In the lens unit 20, the light guide tube 27 has an outer diameter Od1 smaller than the inner diameter Id1 of the tip portion 21t of the outer tube 21, and is supported by the outer peripheral surface of the tip portion of the inner tube 22 in such a manner that an annular gas passage 28 is defined between the inner peripheral surface 21ts of the tip portion 21t of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27. In this way, by supporting the light guide tube 27 by the inner tube 22, the light guide tube 27 can be accurately aligned with respect to the inner tube 22, that is, the objective lens section 23 (wide-angle lens 23w), so that the light irradiated from the light guide tube 27 and reflected inside the hole H can be uniformly incident on the objective lens section 23 (wide-angle lens 23w). Therefore, the inside of the hole H can be photographed with high accuracy by the camera 50.

[0054] Furthermore, when a plurality of different lens units not including the annular gas passage 28 are manufactured by using a plurality of outer tubes having different inner diameters at the tip and a plurality of light guide tubes having different outer diameters, the lens unit 20 including the annular gas passage 28 can be easily manufactured by combining an outer tube having a relatively large inner diameter at the tip and a light guide tube having a relatively small outer diameter. That is, by adopting a structure in which the light guide tube 27 is supported by the inner tube 22, the outer tube 21, the inner tube 22, the light guide tube 27, etc. can be shared between the lens unit 20 including the annular gas passage 28 and the lens unit not including the annular gas passage 28.

[0055] Furthermore, in the lens unit 20, both the outer tube 21 and the inner tube 22 have light shielding properties, and the light guide tube 27 is precisely aligned with respect to the inner tube 22, that is, the objective lens unit 23 (wide-angle lens 23w). Thus, the light from the plurality of bullet-shaped light emitting diodes 30 can be uniformly diffused into the inside of the hole H by the light guide tube 27, and the light irradiated from the light guide tube 27 and reflected in the inside of the hole H can be uniformly incident on the objective lens unit 23, so that the inside of the hole H can be photographed with high precision by the camera 50, and the noise of the photographed image can be well reduced.

[0056] In addition, the lens unit 20 includes an annular substrate 31 connected to the terminals of the plurality of bullet-shaped light emitting diodes 30. In addition, the inner diameter Id1 of the top end portion 21t of the outer tube 21 is smaller than the inner diameter Id0 of the portion on the mounting portion 25 side of the outer tube 21, and the spacer 29 is arranged between the inner peripheral surface 21is of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27 in a manner that is located on the mounting portion 25 side of the top end portion 21t of the outer tube 21 and on the objective lens portion 23 side of the plurality of bullet-shaped light emitting diodes 30. In addition, air is supplied to the annular gas passage 28 from the air piping joint 35 via the space between the outer tube 21 and the inner tube 22, the gap between the inner hole of the substrate 31 and the inner tube 22, the gap between the plurality of bullet-shaped light emitting diodes 30 and the inner tube 22, and the plurality of gas passages 29p of the spacer 29 (see FIG. 2 ). Figure 4 ).

[0057] That is, in the lens unit 20, the spacer 29 is arranged at the portion on the side of the mounting portion 25 having the inner diameter Id0 larger than the inner diameter Id1 of the top end portion 21t of the outer tube 21, and therefore, the degree of freedom of arrangement of the plurality of gas passages 29p relative to the spacer 29 becomes high. Thus, the air from the side of the plurality of bullet-shaped light emitting diodes 30 can be more effectively rectified by using the plurality of gas passages 29p of the spacer 29. In addition, in the lens unit 20, the arrangement space for the plurality of bullet-shaped light emitting diodes 30 corresponding to the required light quantity is ensured at the portion on the side of the mounting portion 25 of the outer tube 21, and by adjusting the inner diameter of the top end portion 21t of the outer tube 21 and the outer diameter of the light guide tube 27, the light guiding performance of the light guide tube 27 and the air ejection performance of the annular gas passage 28 can be appropriately set.

[0058] In the lens unit 20, the inner tube 22 is made of stainless steel, and a black oxide film or black plating is applied to the inner peripheral surface 22is of the inner tube 22. This can suppress the scattering of light from the wide-angle lens 23w (aperture H) toward the camera 50 inside the inner tube 22, that is, the generation of stray light, so that the inside of the aperture H can be photographed with high accuracy by the camera 50.

[0059] Figure 5 2 is a schematic diagram showing another lens unit 20B of the present disclosure. It should be noted that the same reference numerals are used to indicate the same elements as those of the lens unit 20 described above, and duplicate descriptions are omitted.

[0060] like Figure 5As shown in FIG. 1 , the light guide tube 27B of the lens unit 20B has an inner diameter Id2 larger than the outer diameter Od2 of the top end portion of the inner tube 22 and an outer diameter slightly smaller than the inner diameter of the top end portion 21t of the outer tube 21, and is coaxially fitted into the top end portion 21t of the outer tube 21. Thus, the light guide tube 27B is coaxially supported by the inner circumferential surface of the top end portion 21t of the outer tube 21, is surrounded by the top end portion 21t, and surrounds the top end portion of the inner tube 22 via an annular space. That is, between the inner circumferential surface 27is of the light guide tube 27B and the outer circumferential surface 22os of the top end portion of the inner tube 22, an internal space on the side of the mounting portion 25 of the outer tube 21 and an annular gas passage 28B opened at the top ends of the outer tube 21, the inner tube 22, and the light guide tube 27B are divided.

[0061] In addition, an annular spacer 29B is arranged between the outer circumferential surface 22os of the inner tube 22 and the inner circumferential surface 27is of the light guide tube 27B in a manner close to the plurality of bullet-shaped light-emitting diodes 30. That is, the spacer 29B is coaxially embedded in the internal space of the light guide tube 27B, and the inner tube 22 is coaxially embedded in the inner hole of the spacer 29B. Thus, the light guide tube 27B is coaxially held by the outer tube 21 and the inner tube 22 via the spacer 29B. In addition, the spacer 29B also has a plurality of gas passages 29p arranged at intervals (for example, at equal intervals) in the circumferential direction. In the present embodiment, each gas passage 29p is, for example, a groove formed on the inner circumferential surface of the spacer 29B in a manner extending along the axial direction of the spacer 29. When the spacer 29 is arranged between the inner tube 22 and the light guide tube 27B, each gas passage 29p extends along the outer tube 21, the inner tube 22 and the light guide tube 27B in the axial direction of the lens unit 20 and communicates with the annular gas passage 28B between the inner tube 22 and the light guide tube 27B.

[0062] When the lens unit 20B configured as described above is used to photograph the inside of the hole H formed in the workpiece W with the camera 50, by operating the air supply device 40, air can be supplied to the annular gas passage 28B through the space between the outer tube 21 and the inner tube 22, the gap between the inner hole of the substrate 31 and the inner tube 22, the gap between the plurality of bullet-shaped LEDs 30 and the inner tube 22, and the plurality of gas passages 29p of the spacer 29B, and the air can be ejected from between the outer tube 21 and the inner tube 22 to the inside of the hole H. As a result, compared with the case where the air is ejected from the outer periphery of the outer tube 21 to the hole H, foreign matter such as water droplets and chips existing in the inside of the hole H can be removed well, and foreign matter discharged to the outside of the hole H along with the ejection of the gas can be prevented from being attached to the objective lens portion 23.

[0063] In addition, the invention disclosed herein is not limited by the above-mentioned embodiments, and it is self-evident that various changes can be made within the scope of the disclosure. In addition, the above-mentioned embodiments are only a specific mode of the invention described in the invention content, and do not limit the elements of the invention described in the invention content.

[0064] Industrial Applicability

[0065] The disclosed invention is very useful for inspecting the interior of a hole formed in a workpiece in the manufacturing industry.

Claims

1. A hole inspection lens unit for inspecting the inside of a hole formed in a workpiece, wherein: have: A cylindrical outer tube; A cylindrical inner tube inserted into the outer tube; an objective lens disposed in the top end of the inner tube; a mounting portion that supports the base end portion of the outer tube and the base end portion of the inner tube and is mounted with a camera that photographs the inside of the hole via the objective lens; A plurality of bullet-shaped light emitting diodes are arranged inside the outer tube and around the inner tube; a cylindrical light guide tube surrounded by the top end of the outer tube and supported by one of the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube in a manner of surrounding the top end of the inner tube, so as to diffuse and illuminate the light emitted from the plurality of bullet-shaped light emitting diodes on the mounting portion side into the inside of the hole; an annular spacer having a plurality of gas passages and arranged between the light guide tube and the other of the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube in such a manner that the plurality of gas passages extend along the light guide tube; and An annular gas passage is divided between the inner circumference of the outer tube and the outer circumference of the light guide tube, or between the outer circumference of the inner tube and the inner circumference of the light guide tube, is connected to the plurality of gas passages of the spacer, and opens at the top ends of the outer tube and the inner tube.

2. The hole inspection lens unit according to claim 1, wherein: The outer diameter of the light guide tube is smaller than the inner diameter of the top end portion of the outer tube. The light guide tube is supported by the outer peripheral surface of the top end portion of the inner tube. The annular gas passage is defined between the inner peripheral surface of the distal end portion of the outer tube and the outer peripheral surface of the light guide tube.

3. The hole inspection lens unit according to claim 2, wherein: It also has a ring-shaped substrate for connecting the terminals of the plurality of bullet-shaped light-emitting diodes. The inner diameter of the tip portion of the outer tube is smaller than the inner diameter of a portion of the outer tube on the mounting portion side. The spacer is arranged between the inner peripheral surface of the outer tube and the outer peripheral surface of the light guide tube so as to be located on the mounting portion side of the top end portion of the outer tube and on the objective lens side of the plurality of bullet-shaped light emitting diodes. Air is supplied to the annular gas passage through the space between the outer tube and the inner tube, the gap between the inner hole of the substrate and the inner tube, the gap between the plurality of bullet-shaped LEDs and the inner tube, and the plurality of gas passages of the spacer.

4. The hole inspection lens unit according to any one of claims 1 to 3, wherein: The inner tube is formed of stainless steel, A black oxide film or a black plating layer is applied to the inner peripheral surface of the inner tube.

Images