Hole inspection lens unit

Abstract

To reduce noise of an image captured by ensuring uniform illuminance inside a hole when imaging the inside of the hole of a workpiece by a camera, and to satisfactorily remove foreign matter existing inside the hole.SOLUTION: A hole inspection lens unit includes: a cylindrical light guide pipe that is surrounded by an end section of an outer pipe and is supported by one of an outer peripheral surface of an inner pipe and an inner peripheral surface of the outer pipe so as to surround an end section of the inner pipe, and diffusing and applying light emitted from multiple cannonball shaped light emitting diodes in a side of a mount section to the inside of a hole; an annular spacer that has multiple gas passages, and is disposed between the light guide pipe and the other of the outer peripheral surface of the inner pipe and the inner peripheral surface of the outer pipe such that the multiple gas passages extend along the light guide pipe; and an annular gas passage that is defined between the outer peripheral surface of the light guide pipe and the inner peripheral surface of the outer pipe or between the inner peripheral surface of the light guide pipe and the outer peripheral surface of the inner pipe, and communicates with the multiple gas passages of the spacer and is open in the end sections of the outer pipe and the inner pipe.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, a hole defect detection device used for inspecting the inside of a hole formed in a circuit board is known (see, for example, Patent Document 1). This hole defect detection device includes a cylindrical outer casing, a rod mirror inserted into the inside of the outer casing, an objective lens arranged on the protective glass side of the rod mirror, and a connection sleeve that supports the base end of the outer casing and the rod mirror and to which a CCD camera is attached. In addition, an infrared light source processor formed of a fixed plate and a collimating lens are arranged between the outer periphery side of the objective lens and the inner periphery side of the outer casing. The collimating lens is surrounded by the tip of the outer casing on the protective glass side of the infrared light source processor and surrounds the objective lens.

[0003] Also, a conventional inspection method is known in which an insertion shaft with a wide-angle lens at the tip is inserted into a hole and the wall surface of the hole is inspected based on an image through the wide-angle lens (see, for example, Patent Document 2). In this inspection method, when inspecting the wall surface of the hole, gas is ejected toward the back of the hole along the outer circumferential surface of the insertion shaft. This makes it possible to remove foreign matter such as water droplets and chips attached to the wall surface of the hole. Another known inspection method of this type is one in which, when inspecting the wall surface of the hole, a first gas is ejected toward the back of the hole along the outer circumferential surface of the insertion shaft and a second gas having a higher flow rate than the first gas is ejected around the first gas in the same direction as the first gas (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] China Patent Application Publication No. 110823924 [Patent Document 2] JP 2013-088136 A [Patent Document 3] JP 2015-049044 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the hole defect detection device described in the cited document 1, light from an infrared light source processor is irradiated into the inside of the hole through a collimating lens that has the property of transmitting light straight in a specific direction. For this reason, when the hole defect detection device of the cited document 1 is used, it is not possible to ensure uniform illuminance inside the target hole, and there is a risk that noise in the image captured by the CCD camera will increase. On the other hand, when foreign matter such as water droplets is present inside the hole, it is preferable to eject gas toward the hole to remove the foreign matter, as described in the patent documents 2 and 3. However, in the hole defect detection device of the cited document 1, even if gas is ejected along the outer peripheral surface of the outer casing, there is a risk that the foreign matter cannot be removed well from the wall surface of the hole.

[0006] Therefore, the main objective of the present disclosure is to provide a lens unit for hole inspection that can ensure uniform illuminance inside a workpiece hole when imaging the inside of the hole with a camera, thereby reducing noise in the captured image and effectively removing foreign matter present inside the hole. [Means for solving the problem]

[0007] The hole inspection lens unit disclosed herein is a hole inspection lens unit used 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 disposed within the tip of the inner tube, a mount portion that supports the base end of the outer tube and the base end of the inner tube and to which a camera that images the inside of the hole through the objective lens is attached, a plurality of bullet-shaped light-emitting diodes disposed inside and around the inner tube, and a lens support that is surrounded by the tip 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 so as to surround the tip end of the inner tube. the light guide tube is supported by a mounting portion and irradiates light emitted from the plurality of bullet-shaped light-emitting diodes on the mounting portion side while diffusing it into the inside of the hole; an annular spacer having a plurality of gas passages and disposed between the other of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube and the light guide tube such that the plurality of gas passages extend along the light guide tube; and an annular gas passage defined between the inner peripheral surface of the outer tube and the outer peripheral surface of the light guide tube, or between the outer peripheral surface of the inner tube and the inner peripheral surface of the light guide tube, communicating with the plurality of gas passages of the spacer and opening at the tips of the outer tube and the inner tube.

[0008] When the inside of a hole formed in a workpiece is imaged by a camera using the hole inspection lens unit of the present disclosure, the hole inspection lens unit with the camera attached to the mount is stopped so that the objective lens is located above the hole. Furthermore, each bullet-shaped light-emitting diode is caused 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 irradiated while being diffused into the inside of the hole by a cylindrical light guide tube. This makes it possible to ensure uniform illuminance inside the hole when the inside of the hole in the workpiece is imaged by the camera, thereby reducing noise in the image captured by the camera. Furthermore, in the hole inspection lens unit of the present disclosure, the light guide tube is surrounded by the tip of the outer tube and is supported by one of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube so as to surround the tip of the inner tube. Furthermore, an annular spacer having a plurality of gas passages is arranged between the other of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube and the light guide tube, and the plurality of gas passages of the spacer extend along the light guide tube. 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, an annular gas passage is defined that communicates with the multiple gas passages of the spacer and opens at the tip of the outer tube and the inner tube. As a result, when imaging the inside of the hole of the workpiece with a camera, gas can be supplied to the annular gas passage through the multiple gas passages of the spacer, and the gas can be ejected from between the outer tube and the inner tube into the inside of the hole. As a result, compared to the case where gas is ejected from the outer periphery of the outer tube toward the hole, it is possible to effectively remove foreign matter present inside the hole while suppressing adhesion of foreign matter to the objective lens. In addition, in the lens unit for hole inspection of the present disclosure, the gas supplied to the annular gas passage by the multiple gas passages of the spacer is rectified, 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 multiple gas passages. Therefore, according to the lens unit for hole inspection disclosed herein, when imaging the inside of a hole in a workpiece with a camera, uniform illuminance is ensured inside the hole, reducing noise in the captured image and enabling good removal of foreign objects present inside the hole. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram showing a hole inspection system to which a hole inspection lens unit according to the present disclosure is applied; [Diagram 2] FIG. 2 is a vertical cross-sectional view showing a lens unit for hole inspection according to the present disclosure. [Diagram 3] FIG. 2 is an enlarged cross-sectional view showing a main part of the hole inspection lens unit according to the present disclosure. [Figure 4] FIG. 2 is a perspective view showing a main part of a hole inspection lens unit according to the present disclosure. [Diagram 5] FIG. 11 is an enlarged cross-sectional view showing a main portion of another hole inspection lens unit of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Next, an embodiment of the present disclosure will be described with reference to the drawings.

[0011] FIG. 1 is a schematic diagram showing a hole inspection system 1 to which a hole inspection lens unit (hereinafter simply referred to as a "lens unit") 20 of the present disclosure is applied. The hole inspection system 1 shown in the figure 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 case. The hole H to be inspected may be a round hole, a square hole, a threaded hole, a non-threaded hole, a through hole, or a non-through hole. Furthermore, the workpiece W is not limited to a transmission case.

[0012] As shown in FIG. 1, the hole inspection system 1 includes a system control device 2, a plurality of robots 3, a plurality of robot control devices 4 each connected to the system control device 2 and controlling the corresponding robot 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., and controls the hole inspection system 1 in an integrated manner by exchanging signals (information) with the plurality of robot control devices 4 and the inspection processing device 5. Each robot 3 is a robot arm that can hold and move an imaging 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 to move the imaging tool 10 to an inspection work position above the target hole H by a predetermined distance according to a predetermined control procedure.

[0013] The inspection processing device 5 is a computer having a CPU, ROM, RAM, etc. The camera 50 of the imaging tool 10 is connected to the inspection processing device 5 via a connector, cable, etc. provided on the robot 3. Furthermore, an inspection program for inspecting the internal state of the hole H based on an image (image data) of the inside of the hole H captured by the camera 50 is installed in the inspection processing device 5. The inspection program (software) cooperates with hardware such as the CPU, ROM, and RAM of the inspection processing device 5 to implement a neural network that determines (diagnoses) whether the internal state of the hole H is good or bad based on the image captured by the camera 50, for example.

[0014] 2 is a vertical cross-sectional view showing the lens unit 20. As shown in the figure, the lens unit 20 includes an outer tube 21, an inner tube 22, an objective lens section 23, a plurality of relay lenses 24, a mount section 25 to which a camera 50 is attached, a retainer 26, a light guide tube 27, and a plurality of (for example, six in this embodiment) bullet-shaped light-emitting diodes 30.

[0015] The outer tube 21 is formed in a cylindrical shape from a material having a light-shielding property such as metal, and the tip portion 21t of the outer tube 21 is tapered. The inner diameter Id1 of the tip portion 21t of the outer tube 21 is smaller than the inner diameter Id0 of the portion of the outer tube 21 on the mount portion 25 side. The inner tube 22 is formed in a cylindrical shape from a material having a light-shielding property such as metal, and has an outer diameter smaller than the inner diameter of the outer tube 21. In this embodiment, the inner tube 22 is formed from stainless steel, and an inner peripheral surface 22is of the inner tube 22 is coated with a black oxide film or black plating (black chrome plating) by an electrolytic coloring method. The inner tube 22 is inserted coaxially into the outer tube 21 and fixed to the base end portion of the outer tube 21 via a retainer 26.

[0016] The objective lens unit 23 has a wide-angle lens 23w and is disposed (fixed) in the tip of the inner tube 22. The multiple relay lenses 24 are disposed at intervals in the inner tube 22 so as to relay an image from the wide-angle lens 23w to the camera 50 attached to the mount unit 25. This allows the entire inside of the hole H to be focused. In addition, by disposing multiple relay lenses 24 in the inner tube 22, it becomes possible to determine the axial length of the lens unit 20 according to the shape of the work W, and for example, the axial length of the lens unit 20 for imaging the inside of the hole H formed in the bottom of the work W can be made longer. Furthermore, depending on the axial length required for the lens unit 20, a single relay lens 24 may be disposed in the inner tube 22, or the relay lens 24 may be omitted.

[0017] The mount section 25 is fixed to a retainer 26, and supports the base end of the outer tube 21 and the base end of the inner tube 22 via the retainer 26. A male screw 25t conforming to the C-mount standard is formed on the outer peripheral surface of the mount section 25. This allows various industrial cameras conforming to the C-mount standard, which have different specifications such as the number of pixels, to be attached to the mount section 25. Furthermore, an industrial camera conforming to the CS-mount standard can also be attached to the mount section 25 via an adapter.

[0018] The light guide tube 27 is made of glass, quartz, or the like and is formed into a cylindrical shape shorter than the outer tube 21, etc. 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 an inner diameter slightly larger than the outer diameter of the inner tube 22, and the tip portion of the inner tube 22 is coaxially fitted into the light guide tube 27. As a result, 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 through 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 annular gas passage 28 is defined, which opens at the internal space on the mount portion 25 side of the outer tube 21 and the tips of the outer tube 21, the inner tube 22, and the light guide tube 27.

[0019] Furthermore, the end of the light guide tube 27 on the mount section 25 side protrudes from within the tip portion 21t into the internal space on the mount section 25 side of the outer tube 21, and an annular spacer 29 is disposed between the inner circumferential surface 21is of the outer tube 21 and the end of the light guide tube 27 on the mount section 25 side. That is, the spacer 29 is coaxially fitted into the internal space on the mount section 25 side of the outer tube 21, and the end of the light guide tube 27 on the mount section 25 side is coaxially fitted into the inner hole of the spacer 29. As a result, the light guide tube 27 is held coaxially by the outer tube 21 and the inner tube 22 via the spacer 29.

[0020] The spacer 29 also has a plurality of gas passages 29p arranged at intervals (e.g., at equal intervals) in the circumferential direction. In this embodiment, each gas passage 29p is a round hole extending in the axial direction of the spacer 29. However, the gas passage 29p may be, for example, a recess (notch) formed on the inner peripheral surface of the spacer 29. When the spacer 29 is disposed between the outer tube 21 and the light guide tube 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 tube 27, and communicates with the annular gas passage 28 between the tip end 21t of the outer tube 21 and the light guide tube 27.

[0021] The plurality of shell-shaped light-emitting diodes 30 are disposed at intervals (for example, at equal intervals) inside the outer tube 21 and around the inner tube 22 so as to face (contact) the end of the light guide tube 27 on the mount section 25 side of the spacer 29. The terminals of each shell-shaped light-emitting diode 30 are connected to an annular substrate 31, thereby connecting the plurality of shell-shaped light-emitting diodes 30 in series or in parallel. The substrate 31 is disposed on the mount section 25 side of the light-emitting sections of the plurality of shell-shaped light-emitting diodes 30, and a cable (not shown) for supplying power to each shell-shaped light-emitting diode 30 is connected to the substrate 31. The cable is drawn out to the outside of the outer tube 21 through the space between the outer tube 21 and the inner tube 22 and a cable drawing section 21c formed in the outer tube 21, and is connected to a lighting power source (not shown) via a connector.

[0022] Furthermore, an air pipe joint 35 is connected to the outer pipe 21 so as to communicate with the space between the outer pipe 21 and the inner pipe 22 between the mount portion 25 and the substrate 31 in the axial direction. The air pipe joint 35 is connected to an air supply device 40 via an air hose or the like. The air supply device 40 is controlled, for example, by 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 pipe 21 and the inner pipe 22.

[0023] When the camera 50 is used to image the inside of the hole H formed in the workpiece W using the lens unit 20 configured as described above, the imaging tool 10, i.e., the lens unit 20 with the camera 50 attached to the mount portion 25, is moved by the robot 3 so that the objective lens portion 23 (wide-angle lens 23w) is positioned a predetermined distance above the hole H, and is stopped at the inspection work position. Furthermore, each bullet-shaped light-emitting diode 30 is made to emit light. The bullet-shaped light-emitting diode 30 has excellent light-collecting properties, and the light emitted from each bullet-shaped light-emitting diode 30 is irradiated while being diffused inside the hole H by the cylindrical light guide tube 27. As a result, when the camera 50 images the inside of the hole H in the workpiece W, uniform illuminance is ensured inside the hole H, and noise such as light streaks in the image captured by the camera 50 can be extremely effectively reduced.

[0024] In the lens unit 20, the light guide tube 27 is surrounded by the tip 21t of the outer tube 21 and is supported by the outer peripheral surface of the inner tube 22 so as to surround the tip of the inner tube 22. Furthermore, an annular spacer 29 having a plurality of gas passages 29p is disposed 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, etc. An annular gas passage 28 is defined between the inner peripheral surface 21ts of the tip 21t of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27, which communicates with the plurality of gas passages 29p of the spacer 29 and opens at the tips of the outer tube 21, the inner tube 22, and the light guide tube 27.

[0025] As a result, when the inside of the hole H of the workpiece W is imaged by the camera 50, the air supply device 40 is operated to supply air from the air pipe joint 35 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 light-emitting diodes 30 and the inner tube 22, and the plurality of gas passages 29p of the spacer 29 to the annular gas passage 28, and the air can be ejected from between the outer tube 21 and the inner tube 22 into the inside of the hole H, as shown by the dotted line in Fig. 4. As a result, compared to the case where air is ejected from the outer periphery of the outer tube 21 toward the hole H, it is possible to effectively remove foreign matter such as water droplets (cleaning liquid) and cutting chips present inside the hole H while suppressing adhesion of foreign matter to the objective lens portion 23 (wide-angle lens 23w).

[0026] Furthermore, in the lens unit 20, the air supplied to the annular gas passage 28 is rectified by the multiple gas passages 29p of the spacer 29, and the flow speed of the air ejected from the annular gas passage 28 toward the hole H can be increased by adjusting the passage cross-sectional area (opening area) of the multiple gas passages 29p. Therefore, according to the lens unit 20, when the inside of the hole H in the workpiece W is imaged by the camera 50, uniform illuminance is ensured inside the hole H, reducing noise in the image, and foreign matter present inside the hole H can be effectively removed.

[0027] In the lens unit 20, the light guide tube 27 has an outer diameter Od1 smaller than the inner diameter Id1 of the tip 21t of the outer tube 21, and is supported by the outer peripheral surface of the tip of the inner tube 22 so that an annular gas passage 28 is defined between the inner peripheral surface 21ts of the tip 21t of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27. By supporting the light guide tube 27 by the inner tube 22 in this manner, the light guide tube 27 can be accurately aligned with the inner tube 22, i.e., the objective lens unit 23 (wide-angle lens 23w), so that light irradiated from the light guide tube 27 and reflected inside the hole H can be uniformly incident on the objective lens unit 23 (wide-angle lens 23w). Therefore, the inside of the hole H can be imaged by the camera 50 with high accuracy.

[0028] In addition, when a plurality of different types of lens units not including the annular gas passage 28 are manufactured from a plurality of outer tubes having different inner diameters at their tips and a plurality of light guide tubes having different outer diameters, it is possible to easily manufacture the lens unit 20 including the annular gas passage 28 by combining an outer tube having a relatively large inner diameter at its tip with 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 lens unit 20 not including the annular gas passage 28 and the lens unit not including the annular gas passage 28 can share the outer tube 21, the inner tube 22, the light guide tube 27, etc.

[0029] 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 the inner tube 22, i.e., the objective lens section 23 (wide-angle lens 23w). This allows the light from the multiple bullet-shaped light-emitting diodes 30 to be uniformly diffused inside the hole H by the light guide tube 27, and allows the light irradiated from the light guide tube 27 and reflected inside the hole H to be uniformly incident on the objective lens section 23, making it possible for the camera 50 to capture an image of the inside of the hole H with high precision and to satisfactorily reduce noise in the captured image.

[0030] Furthermore, the lens unit 20 includes an annular substrate 31 to which terminals of the plurality of bullet-shaped light-emitting diodes 30 are connected. The inner diameter Id1 of the tip 21t of the outer tube 21 is smaller than the inner diameter Id0 of the portion of the outer tube 21 on the mount section 25 side, and the spacer 29 is disposed between the inner peripheral surface 21is of the outer tube 21 and the outer peripheral surface 27os of the light guide tube 27 so as to be located on the mount section 25 side of the tip 21t of the outer tube 21 and on the objective lens section 23 side of the plurality of bullet-shaped light-emitting diodes 30. Furthermore, air is supplied to the annular gas passage 28 from the air pipe joint 35 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 light-emitting diodes 30 and the inner tube 22, and the plurality of gas passages 29p of the spacer 29 (see FIG. 4).

[0031] That is, in the lens unit 20, the spacer 29 is disposed in a portion on the mount section 25 side having an inner diameter Id0 larger than the inner diameter Id1 of the tip 21t of the outer tube 21, so that the degree of freedom in disposing the plurality of gas passages 29p for the spacer 29 is increased. This allows the plurality of gas passages 29p of the spacer 29 to more effectively rectify the air from the side of the plurality of bullet-shaped light-emitting diodes 30. In addition, in the lens unit 20, a disposing space for the plurality of bullet-shaped light-emitting diodes 30 corresponding to the required light quantity is secured in the portion on the mount section 25 side of the outer tube 21, and the light guiding performance of the light guiding tube 27 and the air ejection performance of the annular gas passage 28 can be appropriately set by adjusting the inner diameter of the tip 21t of the outer tube 21 and the outer diameter of the light guiding tube 27.

[0032] 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 makes it possible to suppress scattering of light from the wide-angle lens 23w (hole H) toward the camera 50 inside the inner tube 22, i.e., generation of stray light, and therefore makes it possible for the camera 50 to capture an image of the inside of the hole H with high accuracy.

[0033] 5 is a schematic diagram showing another lens unit 20B of the present disclosure. Note that, among the components of the lens unit 20B, the same components as those of the above-described lens unit 20 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0034] 5, the light guide tube 27B of the lens unit 20B has an inner diameter Id2 larger than the outer diameter Od2 of the tip of the inner tube 22 and an outer diameter slightly smaller than the inner diameter of the tip 21t of the outer tube 21, and is coaxially fitted into the tip 21t of the outer tube 21. As a result, the light guide tube 27B is coaxially supported by the inner circumferential surface of the tip 21t of the outer tube 21 and surrounded by the tip 21t, and surrounds the tip of the inner tube 22 through 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 tip of the inner tube 22, an annular gas passage 28B is defined, which opens at the internal space on the mount part 25 side of the outer tube 21 and the tips of the outer tube 21, the inner tube 22, and the light guide tube 27B.

[0035] In addition, an annular spacer 29B is disposed between the outer peripheral surface 22os of the inner tube 22 and the inner peripheral surface 27is of the light guide tube 27B so as to be close to the plurality of shell-shaped light emitting diodes 30. That is, the spacer 29B is coaxially fitted into the inner space of the light guide tube 27B, and the inner tube 22 is coaxially fitted into the inner hole of the spacer 29B. As a result, the light guide tube 27B is held coaxially by the outer tube 21 and the inner tube 22 via the spacer 29B. The spacer 29B also has a plurality of gas passages 29p arranged at intervals (for example, at equal intervals) in the circumferential direction. In this embodiment, each gas passage 29p is, for example, a groove formed on the inner peripheral surface of the spacer 29B so as to extend in the axial direction of the spacer 29. When the spacer 29 is disposed between the inner tube 22 and the light guide tube 27B, 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 tube 27B, and communicates with the annular gas passage 28B between the inner tube 22 and the light guide tube 27B.

[0036] When the inside of the hole H formed in the workpiece W is imaged by the camera 50 using the lens unit 20B configured as described above, the air supply device 40 is operated to supply air 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 light-emitting diodes 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 into the inside of the hole H. As a result, compared to the case where air is ejected from the outer periphery of the outer tube 21 toward the hole H, it is possible to effectively remove foreign matter such as water droplets and chips present inside the hole H, and to effectively prevent the foreign matter discharged outside the hole H in response to the ejection of gas from adhering to the objective lens portion 23.

[0037] It goes without saying that the invention of this disclosure is not limited to the above embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0038] The invention disclosed herein is extremely useful for inspecting the inside of holes formed in workpieces in the manufacturing industry. [Explanation of symbols]

[0039] 1 hole inspection system, 10 imaging tool, 20, 20B lens unit, 21 outer tube, 21is, 21ts, 27is inner surface, 21t tip portion, 22 inner tube, 22os, 27os outer surface, 23 objective lens portion, 23w wide-angle lens, 27, 27B light guide tube, 28, 28B annular gas passage, 29, 29B spacer, 29p gas passage, 30 bullet-type light-emitting diode, 31 substrate, 40 air supply device, 50 camera, W work.

Claims

1. A hole inspection lens unit used for inspecting the inside of a hole formed in a workpiece, A cylindrical outer tube; A cylindrical inner tube that is inserted into the outer tube; an objective lens disposed within a tip of the inner tube; a mount portion to which a camera is attached, the mount portion supporting a base end portion of the outer tube and a base end portion of the inner tube and configured to capture an image of the inside of the hole through the objective lens; A plurality of bullet-type light-emitting diodes are disposed inside the outer tube and around the inner tube; a cylindrical light guide tube that is surrounded by the tip end of the outer tube and is supported by one of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube so as to surround the tip end of the inner tube, and that irradiates light emitted from the plurality of bullet-shaped light emitting diodes on the mount side while diffusing the light into the hole; an annular spacer having a plurality of gas passages and disposed between the other of the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube and the light guide tube such that the plurality of gas passages extend along the light guide tube; an annular gas passage defined between the inner peripheral surface of the outer tube and the outer peripheral surface of the light guide tube, or between the outer peripheral surface of the inner tube and the inner peripheral surface of the light guide tube, the annular gas passage communicating with the plurality of gas passages of the spacer and opening at the tip of the outer tube and the inner tube; A hole inspection lens unit comprising:

2. 2. The hole inspection lens unit according to claim 1, an outer diameter of the light guide tube is smaller than an inner diameter of the tip portion of the outer tube; the light guide tube is supported by an outer circumferential surface of the tip portion of the inner tube, The annular gas passage is defined between an inner peripheral surface of the tip portion of the outer tube and the outer peripheral surface of the light guide tube.

3. 3. The hole inspection lens unit according to claim 2, The light emitting diode further includes an annular substrate to which terminals of the plurality of bullet-type light emitting diodes are connected, an inner diameter of the tip portion of the outer tube is smaller than an inner diameter of a portion of the outer tube on the mount portion side; the spacer is disposed between the inner circumferential surface of the outer tube and the outer circumferential surface of the light guide tube so as to be located on the mount side of the tip portion of the outer tube and on the objective lens side of the plurality of bullet-type light-emitting diodes; A hole inspection lens unit to which air is supplied in 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 light-emitting diodes 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, The inner tube is made of stainless steel, The hole inspection lens unit has an inner peripheral surface of the inner tube that is coated with a black oxide film or black plating.

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