Inspection Equipment

Abstract

To solve the problem with a color of a flow detection liquid, if too pale, being unable to obtain an image contrast sufficient to inspect defects.SOLUTION: An illumination unit 16 of an inspection device 10 has a rectangular shape extending in a Y direction, and radiates a line-shaped ultraviolet light 24 along the Y direction onto a surface 22 of a sensor element 12 in which defects are impregnated with a fluorescent flaw detection liquid. A photographing unit 18 of the inspection device 10 has sensitivity in a wavelength band of fluorescence 28 emitted from the fluorescent flaw detection liquid irradiated with the ultraviolet light 24, and photographs the surface 22 of the sensor element 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an inspection device. [Background technology]

[0002] Patent Document 1 discloses an inspection device for sensor elements. This inspection device inspects for minute defects formed on the surface of a sensor element during the manufacturing process of the sensor element. Specifically, flaw detection liquid is applied to the surface of the sensor element by coating or immersion. The flaw detection liquid applied to the sensor surface soaks into the defects. Next, the surface of the sensor element is cleaned. Next, the sensor element is dried. Next, an operator visually inspects the surface of the sensor element to check for defects by checking the locations where the flaw detection liquid has soaked in. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4980389 Summary of the Invention [Problem to be solved by the invention]

[0004] The above inspections are all performed manually by workers, which requires high personnel costs and a long tact time. In contrast, when automating the above inspections, it is possible to take an image of the surface of the sensor element with a camera and check the captured image to inspect for defects. However, if the color of the flaw detection liquid is light, it is not possible to obtain an image contrast sufficient to inspect for defects.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] One aspect of the present invention is an inspection device for inspecting microscopic defects formed on the surface of a sensor element extending in a predetermined direction, the inspection device comprising: an illumination unit having a rectangular shape extending in the predetermined direction, which irradiates a line-shaped ultraviolet light along the predetermined direction onto the surface of the sensor element having fluorescent flaw detection liquid soaked into the defect; and an imaging unit having sensitivity to the wavelength band of fluorescence emitted from the fluorescent flaw detection liquid irradiated with the ultraviolet light, and which images the surface of the sensor element. Effect of the Invention

[0007] According to the present invention, the surface of the sensor element can be uniformly irradiated with ultraviolet light in a predetermined direction. This allows the fluorescent flaw detection liquid that has soaked into the defect to emit fluorescence with higher intensity (brightness). Furthermore, since the imaging unit has sensitivity to the wavelength band of the fluorescence, an image with high contrast can be acquired. As a result, the contrast of the fluorescent flaw detection liquid reflected in the image of the surface of the sensor element can be improved. This allows fine defects formed on the surface of the sensor element to be easily inspected. Furthermore, it is possible to prevent the presence of fine defects from being overlooked. Therefore, in the present invention, the inspection of fine defects formed on the surface of the sensor element can be automated. As a result, it is possible to reduce personnel costs and shorten the takt time. Specifically, the takt time can be shortened to about 1 / 3 compared to the case of performing the inspection manually. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of the inspection device. [Diagram 2] FIG. 2 is a perspective view of the illumination unit and the sensor element. [Diagram 3] FIG. 3A is a diagram showing an image of a comparative example, and FIG. 3B is a diagram showing an image of an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Fig. 1 is a configuration diagram of an inspection device 10 according to this embodiment. Fig. 2 is a perspective view of the inspection device 10. The inspection device 10 is a device for inspecting a sensor element 12 during the manufacturing process of the sensor element 12 in a factory. Specifically, the inspection device 10 is a device for inspecting the manufactured sensor element 12 for minute defects (not shown) formed on a surface 14 of the sensor element 12.

[0010] 2, the sensor element 12 has an elongated shape. In the following description, the longitudinal direction (predetermined direction) of the sensor element 12 is defined as the Y direction. The lateral direction of the sensor element 12 is defined as the X direction. The direction perpendicular to the X direction and the Y direction is defined as the Z direction.

[0011] The sensor element 12 is a gas sensor element that measures a predetermined gas concentration in a measurement gas. The sensor element 12 is a gas sensor element that uses ceramics. The sensor element 12 is manufactured as follows. First, a plurality of ceramic green sheets on which a predetermined pattern is printed are prepared. Next, the plurality of ceramic green sheets are stacked to form a laminate. Next, the laminate is fired to form the sensor element 12.

[0012] During the manufacture of the sensor element 12, minute defects may occasionally be formed on the surface 14 of the sensor element 12. The minute defects are defects formed on the surface 14 of the sensor element 12 due to, for example, the inclusion of foreign matter, stacking defects, and the like.

[0013] Therefore, in the factory, it is necessary to separate the manufactured sensor elements 12 into sensor elements 12 without defects (good products) and sensor elements 12 with defects (defective products). The inspection device 10 is a device for automatically inspecting for such minute defects.

[0014] When inspecting the sensor element 12, the sensor element 12 is immersed in a fluorescent flaw detection liquid (not shown) in advance. After pulling the sensor element 12 out of the fluorescent flaw detection liquid, the inspection device 10 detects the portion of the sensor element 12 that has been soaked with the fluorescent flaw detection liquid, thereby inspecting for defects.

[0015] As shown in FIG. 1, the inspection device 10 includes two illumination units 16, an imaging unit 18, and a computer 20.

[0016] 2, each of the two illumination units 16 is a rectangular light source extending in one direction. Each of the two illumination units 16 is disposed to face, for example, the upper surface 22 of the surface 14 of the sensor element 12. In the following description, for convenience, the upper surface 22 of the sensor element 12 will be referred to as the "surface 22 of the sensor element 12."

[0017] Each of the two illumination units 16 is disposed along the Y direction while being spaced apart from the sensor element 12. That is, the two illumination units 16 are disposed parallel to the sensor element 12. Each of the two illumination units 16 irradiates a line-shaped ultraviolet light 24 onto the surface 22 of the sensor element 12.

[0018] 1, the imaging unit 18 is disposed so as to face the surface 22 of the sensor element 12 while being spaced apart from the sensor element 12. The imaging unit 18 is a camera that captures an image of the surface 22 of the sensor element 12. The imaging unit 18 outputs the captured image of the surface 22 of the sensor element 12 to a computer 20.

[0019] The imaging section 18 is disposed so that an optical axis 26 of the imaging section 18 is perpendicular to the surface 14 of the sensor element 12. In other words, the optical axis 26 of the imaging section 18 is parallel to the Z direction.

[0020] The fluorescent flaw detection liquid that has soaked into the flaw emits fluorescence 28 when irradiated with ultraviolet light 24 from each of the two illumination units 16. The fluorescence 28 is, for example, green light. The imaging unit 18 has sensitivity to the wavelength band of the fluorescence 28.

[0021] The two illumination units 16 are disposed apart from the imaging unit 18 on a plane (XZ plane shown in FIG. 1) perpendicular to the Y direction so as to sandwich the imaging unit 18. Specifically, the two illumination units 16 are disposed symmetrically on this plane with the imaging unit 18 and the optical axis 26 of the imaging unit 18 in between. The two illumination units 16 are positioned on this plane so as to be separated from the optical axis 26 of the imaging unit 18 by a distance Lx of 50 mm to 90 mm in the X direction. The distance Lx is the distance between the optical axis 26 along the X direction and the base end of the illumination unit 16.

[0022] The two illumination units 16 are positioned a distance Lz1 of 45 mm to 90 mm away from the surface 14 of the sensor element 12 in the Z direction along the optical axis 26 of the imaging unit 18. The distance Lz1 is the distance between the surface 14 of the sensor element 12 and the tips of the illumination units 16 in the Z direction.

[0023] Moreover, each of the two illumination units 16 is disposed so that the optical axis 30 of the ultraviolet light 24 is inclined at an angle θ with respect to the optical axis 26 of the imaging unit 18 in this plane. That is, each of the two illumination units 16 is disposed so that the optical axis 30 of the ultraviolet light 24 is inclined at an angle φ (φ=90°-θ) (a predetermined angle) with respect to the surface 22 of the sensor element 12. Each of the two illumination units 16 irradiates the linear ultraviolet light 24 from an oblique direction to the surface 22 of the sensor element 12. The angles θ and φ are set within a range of 40° to 50°. It is more preferable that θ=φ=45°.

[0024] 1, an intersection 32 between the optical axis 26 of the imaging unit 18 and the optical axis 30 of the ultraviolet light 24 irradiated from each of the two illumination units 16 is set on the surface 22 of the sensor element 12. This intersection 32 is provided in the center of the surface 22 of the sensor element 12 in the XZ plane shown in FIG 1. Note that the intersection 32 may be provided at any position on the surface 22 of the sensor element 12.

[0025] As described above, since the linear ultraviolet light 24 is irradiated obliquely onto the surface 22 of the sensor element 12, the fluorescence 28 emitted from the fluorescent flaw detection liquid may not be parallel to the optical axis 26 of the imaging unit 18. That is, the fluorescence 28 may have directionality. Therefore, the imaging unit 18 has a telecentric lens 34. The telecentric lens 34 converts the fluorescence 28 that reaches the telecentric lens 34 into light parallel to the optical axis 26 of the imaging unit 18. The imaging unit 18 captures an image of the surface 22 of the sensor element 12 via the telecentric lens 34.

[0026] The telecentric lens 34 is positioned so as to be separated from the surface 14 of the sensor element 12 by a distance Lz2 of 100 mm to 300 mm in the Z direction along the optical axis 26 of the imaging section 18. The distance Lz2 is the distance between the surface 14 of the sensor element 12 and the tip end (lower end) of the telecentric lens 34 in the Z direction.

[0027] The computer 20 is a control device that controls the two lighting units 16 and the imaging unit 18. The computer 20 is also a processing device that performs predetermined processing on the image input from the imaging unit 18. The processed image is displayed on a display (not shown).

[0028] Next, a method of inspecting the sensor element 12 using the inspection device 10 will be described.

[0029] First, the fluorescent flaw detection liquid is applied to the surface 14 of the manufactured sensor element 12 by coating or immersion. If minute defects are formed on the sensor surface 14, the fluorescent flaw detection liquid applied to the sensor surface 14 will soak into the defects. Next, the surface 14 of the sensor element 12 is washed with water or the like. This removes the fluorescent flaw detection liquid that has been applied to the surface 14 of the sensor element 12. Next, the sensor element 12 is dried to remove the water or the like used for washing.

[0030] Next, the inspection device 10 is used to inspect the surface 14 of the sensor element 12 for minute defects.

[0031] In this inspection, first, the sensor element 12, the imaging section 18, and the two illumination sections 16 are arranged as shown in FIGS.

[0032] Next, the computer 20 controls the imaging unit 18 to start imaging the surface 22 of the sensor element 12 by the imaging unit 18 .

[0033] Furthermore, the computer 20 controls the two illumination units 16 to start emitting ultraviolet light 24 from the two illumination units 16. As a result, a line of ultraviolet light 24 is emitted from each of the two illumination units 16 toward the surface 22 of the sensor element 12. The fluorescent flaw detection liquid that has soaked into the defect absorbs the energy of the irradiated ultraviolet light 24 and emits fluorescence 28.

[0034] The imaging unit 18 continuously or intermittently images the surface 22 of the sensor element 12 via the telecentric lens 34. The imaging unit 18 images the surface 22 of the sensor element 12 including the fluorescence 28 emitted from the fluorescent flaw detection liquid. The imaging unit 18 outputs the image of the surface 22 of the sensor element 12 that has been captured to the computer 20.

[0035] The computer 20 performs a predetermined process on the image input from the imaging unit 18. The computer 20 displays the processed image on a display.

[0036] Figures 3A and 3B show images of the surface 22 of the sensor element 12 (see Figures 1 and 2). Figure 3A is an image of a comparative example. The image of the comparative example is an image of the surface 22 of a sensor element 12 having a defect soaked in with dye flaw detection liquid. Figure 3B is an image of the surface 22 of a sensor element 12 having a defect soaked in with fluorescent flaw detection liquid. In other words, Figure 3B is an image (image of the example) obtained using the inspection device 10.

[0037] In the image of the comparative example shown in FIG. 3A, the lower left portion shows a portion (defect) where the dyed flaw detection liquid has soaked in. However, in the image of the comparative example, the brightness difference between the portion where the dyed flaw detection liquid has soaked in and the other portion is small. Specifically, in the image of the comparative example shown in FIG. 3A, the brightness of the portion (defect) where the dyed flaw detection liquid has soaked in is 130. The brightness of the other portion (non-defect) is 160. Therefore, the brightness difference of the image of the comparative example is 30 (160-130=30). That is, the contrast between the portion where the dyed flaw detection liquid has soaked in and the other portion is low. This is because the color of the dyed flaw detection liquid is light. Therefore, even if the image of the comparative example is checked, it is difficult to identify the portion where the dyed flaw detection liquid has soaked in.

[0038] In contrast, in the image of the embodiment shown in FIG. 3B, the area (defect) where the dyed flaw detection liquid has soaked in is also reflected in the lower left part. In the image of the embodiment, the brightness of the area (defect) where the fluorescent flaw detection liquid has soaked in is high, and the brightness of the other areas is low. Specifically, in the image of the embodiment shown in FIG. 3B, the brightness of the area (defect) where the dyed flaw detection liquid has soaked in is 240. The brightness of the other areas (non-defect) is 50. Therefore, the brightness difference of the image of the embodiment is 190 (240-50=190). As a result, the brightness difference of the image of the embodiment is improved by about six times compared to the image of the comparative example. This increases the contrast between the area where the fluorescent flaw detection liquid has soaked in and the other areas.

[0039] In this manner, in this embodiment, the fluorescent flaw detection liquid is used, and the configuration of the inspection device 10 is devised to improve the contrast of the image. As a result, the location where the fluorescent flaw detection liquid has permeated can be easily identified. Therefore, in the image of the embodiment, it is easy to inspect for defects.

[0040] Through the above inspection, the sensor element 12 that does not have any defects is determined to be a non-defective product, whereas the sensor element 12 that has any defects is determined to be a defective product.

[0041] The present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

[0042] The invention that can be understood from the above-described embodiments will be described below.

[0043] An aspect of the present invention is an inspection device (10) for inspecting minute defects formed on a surface (14, 22) of a sensor element (12) extending in a predetermined direction, the inspection device comprising: an illumination unit (16) having a rectangular shape extending in the predetermined direction, which irradiates a line-shaped ultraviolet light (24) along the predetermined direction onto the surface of the sensor element having fluorescent flaw detection liquid soaked into the defect; and an imaging unit (18) having sensitivity in the wavelength band of fluorescence (28) emitted from the fluorescent flaw detection liquid irradiated with the ultraviolet light, and which images the surface of the sensor element.

[0044] According to the present invention, the surface of the sensor element can be uniformly irradiated with ultraviolet light in a predetermined direction. This allows the fluorescent flaw detection liquid that has soaked into the fine defects to emit fluorescence with higher intensity (brightness). In addition, since the imaging unit has sensitivity to the wavelength band of the fluorescence, an image with high contrast can be acquired. As a result, the location of the fluorescent flaw detection liquid reflected in the image of the surface of the sensor element becomes clear. In this way, the contrast of the image is improved, so that an image with sufficient contrast for inspecting fine defects can be acquired. This makes it possible to easily inspect fine defects and prevent the presence of fine defects from being overlooked. Therefore, in the present invention, the inspection of fine defects formed on the surface of the sensor element can be automated. As a result, it is possible to reduce personnel costs and shorten the takt time. Specifically, the takt time can be shortened to about 1 / 3 compared to the case of performing the inspection manually.

[0045] In an aspect of the present invention, the imaging unit is arranged so that the optical axis (26) of the imaging unit is perpendicular to the surface of the sensor element onto which the ultraviolet light is irradiated, and the illumination unit is arranged so that the optical axis (30) of the ultraviolet light irradiated from the illumination unit is inclined at a predetermined angle (90°-θ, φ) with respect to the surface of the sensor element in a direction perpendicular to the predetermined direction.

[0046] This makes it possible to increase the working distance between the illumination unit and the surface of the sensor. As a result, the surface of the sensor element can be evenly irradiated with ultraviolet light in a direction perpendicular to the predetermined direction. In addition, the directionality of the fluorescence can be suppressed. This makes it possible to further improve the contrast of the image on the surface of the sensor element. In addition, it is possible to prevent the illumination unit from being captured in the image.

[0047] In an aspect of the present invention, the inspection device is provided with two of the illumination units, and the two illumination units are arranged at a distance from the imaging unit so as to sandwich the imaging unit in a direction perpendicular to the specified direction.

[0048] This allows more ultraviolet light to be irradiated onto the surface of the sensor element. As a result, the directionality of the fluorescence to the image can be eliminated, further improving the contrast of the image. In addition, it is possible to prevent two illumination units from appearing in the image.

[0049] In an aspect of the present invention, the two illumination units are disposed symmetrically across the imaging unit and the optical axis of the imaging unit in a direction perpendicular to the predetermined direction.

[0050] This further reduces the directivity of the fluorescence to the image, making it possible to obtain an image with higher contrast.

[0051] In an aspect of the present invention, the optical axis of the ultraviolet light is inclined within a range of 40° to 50° with respect to the optical axis of the imaging unit in a direction perpendicular to the predetermined direction.

[0052] This allows the surface of the sensor element to be evenly irradiated with ultraviolet light, reduces the directivity of fluorescent light, and reliably prevents the illumination unit from appearing in an image.

[0053] In an aspect of the present invention, the illumination unit is located at a distance (Lx) of 50 mm to 90 mm from the optical axis of the imaging unit in a direction perpendicular to the predetermined direction.

[0054] This allows the surface of the sensor element to be evenly irradiated with ultraviolet light, reduces the directivity of fluorescent light, and more reliably prevents the illumination unit from appearing in an image.

[0055] In an aspect of the present invention, the illumination unit is located at a distance (Lz1) of 45 mm to 90 mm from the surface of the sensor element in a direction along the optical axis of the imaging unit.

[0056] Even in this case, the working distance between the illumination unit and the surface of the sensor can be increased, and the surface of the sensor element can be evenly irradiated with ultraviolet light.

[0057] In an aspect of the present invention, the imaging section has a telecentric lens (34) and images the surface of the sensor element via the telecentric lens.

[0058] As a result, the fluorescence that reaches the telecentric lens is converted by the telecentric lens into light parallel to the optical axis of the imaging unit, eliminating the effect of the directivity of the fluorescence on the image, thereby further improving the contrast of the image.

[0059] In an aspect of the present invention, the telecentric lens is located at a distance (Lz2) of 100 mm to 300 mm from the surface of the sensor element in a direction along the optical axis of the imaging section.

[0060] This makes it possible to eliminate the effect of fluorescence directionality on the image while increasing the working distance between the telecentric lens and the surface of the sensor element. [Explanation of symbols]

[0061] 10. Inspection equipment 12...Sensor element 14, 22…Surface 16…Lighting section 18…Imaging unit 24...Ultraviolet light 28...Fluorescence

Claims

1. An inspection apparatus for inspecting a minute defect formed on a surface of a sensor element extending in a predetermined direction, comprising: Two illumination units each having a rectangular shape extending in the predetermined direction, irradiating a linear ultraviolet light along the predetermined direction onto a surface of the sensor element in which a fluorescent flaw detection liquid has been soaked into the defect; an imaging unit having sensitivity to a wavelength band of fluorescence emitted from the fluorescent flaw detection liquid irradiated with the ultraviolet light, and imaging a surface of the sensor element; Equipped with the imaging unit is disposed such that an optical axis of the imaging unit is perpendicular to a surface of the sensor element on which the ultraviolet light is irradiated; An inspection device wherein the two illumination units are positioned on either side of the imaging unit in a direction perpendicular to the specified direction, and are spaced apart from the imaging unit so that the optical axis of the ultraviolet light irradiated from the illumination units is inclined at a specified angle with respect to the surface of the sensor element.

2. 2. The inspection device according to claim 1, An inspection device, wherein the two illumination units are arranged symmetrically across the imaging unit and the optical axis of the imaging unit in a direction perpendicular to the specified direction.

3. 3. The inspection device according to claim 1, An inspection device, wherein the optical axis of the ultraviolet light is inclined within a range of 40° to 50° with respect to the optical axis of the imaging unit in a direction perpendicular to the predetermined direction.

4. In the inspection device according to any one of claims 1 to 3, An inspection device, wherein the illumination unit is positioned at a distance of 50 mm to 90 mm from the optical axis of the imaging unit in a direction perpendicular to the specified direction.

5. In the inspection device according to any one of claims 1 to 4, An inspection apparatus, wherein the illumination unit is located at a distance of 45 mm to 90 mm from the surface of the sensor element in a direction along the optical axis of the imaging unit.

6. In the inspection device according to any one of claims 1 to 5, The imaging unit has a telecentric lens and images a surface of the sensor element via the telecentric lens.

7. 7. The inspection apparatus according to claim 6, The telecentric lens is positioned at a distance of 100 mm to 300 mm from the surface of the sensor element in a direction along the optical axis of the imaging unit.

Images