Inspection system

Abstract

We provide an inspection system that can capture images with minimal uniformity in an inexpensive and space-saving manner. [Solution] The inspection system 100 is a system for inspecting the surface (inspection surface Wa) of a workpiece W. The inspection system 100 includes a transport pallet 10 (transport unit) for transporting the workpiece W, a reflector 20 (reflector unit) provided on the transport pallet 10, a bar light 30 (lighting unit) positioned above the reflector 20 and irradiating the reflector 20 with light, and a camera 40 (imaging unit) positioned above the transport pallet 10 and imaging the surface of the workpiece W. Light L irradiated from the bar light 30 is specularly reflected by the reflector 20 (arrow A), the light specularly reflected by the reflector 20 is specularly reflected by the surface of the workpiece W (arrow B), and the light specularly reflected by the surface of the workpiece W is irradiated by the camera 40 (arrow C).

Description

Technical Field

[0001] The present invention relates to an inspection system.

Background Art

[0002] As a conventional technique, a technique such as Patent Document 1 is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As conventional techniques, various techniques have been proposed, but an inspection system that can capture an image with reduced unevenness at a low cost and in a space-saving manner is desired.

[0005] Therefore, an object of the present invention is to provide an inspection system that can capture an image with reduced unevenness at a low cost and in a space-saving manner.

Means for Solving the Problems

[0006] The present invention employs the following means for solving the problems. Note that the following means for solving the problems are merely examples, and the present invention is not limited thereto. Further, the present invention can be an invention including at least one of the invention-specific matters shown in the following means for solving the problems. Furthermore, elements for limiting the invention-specific matters can be added to the invention-specific matters shown in the following means for solving the problems to make them subordinate concepts, and elements for limiting the invention-specific matters can also be deleted to make them superordinate concepts.

[0007] The inspection system for the solution is, for example, an inspection system for inspecting the surface of a workpiece, comprising: a transport unit for transporting the workpiece; a reflecting unit provided on the transport unit; an illumination unit positioned above the transport unit and irradiating light onto the reflecting unit; and an imaging unit positioned above the transport unit and imaging the surface of the workpiece, wherein the light irradiated from the illumination unit is specularly reflected by the reflecting unit, the light specularly reflected by the reflecting unit is specularly reflected by the surface of the workpiece, and the light specularly reflected by the surface of the workpiece is irradiated onto the imaging unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an inspection system that can capture images with reduced uniformity in an inexpensive and space-saving manner. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the inspection system 100 of the embodiment. [Figure 2] This is a perspective view showing the inspection system 100 of the embodiment. [Figure 3] This diagram illustrates the necessity of specular reflection images. [Figure 4] This diagram shows the inspection method for the comparative example. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. The following embodiments are shown as preferred examples of inspection systems, and embodiments are not limited to these examples.

[0011] Figure 1 shows an inspection system 100 according to an embodiment. Figure 1(A) shows a plan view of the inspection system 100, and Figure 1(B) shows a side view of the inspection system 100. The inspection system 100 is a system for inspecting the surface of the workpiece W. Workpiece W is, for example, a cell case (aluminum pressed) for lithium-ion batteries used in hybrid and electric vehicles. Workpiece W is a hollow case with an open top, a bottom, and four sides. Workpiece W measures approximately 70mm in length, 300mm in width, and 40mm in thickness. However, Workpiece W is not limited to metal; it can be applied to any shape or material.

[0012] The inspection system 100 comprises a transport pallet 10 (transport unit), a reflector 20 (reflector unit), a bar light 30 (lighting unit, light source), and a camera 40 (imaging unit). The inspection system 100 performs a visual inspection of the workpiece W on the transport pallet 10.

[0013] The transport pallet 10 is a flat, rectangular parallelepiped-shaped component that transports the workpiece W. The transport pallet 10 is equipped with wheels (not shown) or the like for moving on rails (not shown). Furthermore, the transport pallet 10 is provided with two pins (not shown), and the opening on the top surface of the workpiece W is fitted onto these two pins and secured.

[0014] The reflector 20 is a component (reflective diffuser) provided on the transport pallet 10. The reflector 20 is attached to the upper surface of the transport pallet 10. The reflector 20 can be fixed to the upper surface of the transport pallet 10 using screws or the like.

[0015] The reflector 20 is preferably an off-white color that is neither too shiny nor too black. Furthermore, the reflector 20 is preferably made of resin. The polymer resin "Delrin" is more preferable for the material of the reflector 20 in terms of cost and reflective performance. The reflector 20 can be an off-white resin plate.

[0016] Incidentally, although it may be considered that a mirror might be better for the reflector 20, doing so would cause halation (a phenomenon where the periphery of the subject becomes blurred and whitish and lacks clarity). Therefore, a surface of the reflector 20 that is too smooth and shiny is not very preferable. The reflector 20 should preferably reduce the light amount without reducing the light quantity and appropriately diffuse the light, and it is a milky white resin plate.

[0017] Also, from the perspective of diffusing light, the surface of the reflector 20 is preferably somewhat rough. However, since it is difficult to mass-produce rough ones, the reflector 20 can use the resin in the state of just purchasing the material. Also, the color of the reflector 20 may be gray. However, since gray is close to black and the amount of light absorbed also increases, a larger amount of light is required for the bar illumination 30.

[0018] The bar illumination 30 is a device that is arranged above the transport pallet 10 and irradiates light onto the reflector 20. As shown in FIG. 1(A), the bar illumination 30 has a light emitting surface 31 with a length L2 (length in the longitudinal direction) that is longer than the length L1 (length in the longitudinal direction) of the surface of the work W imaged by the camera 40 in the horizontal direction. Also, as shown in FIG. 1(B), the bar illumination 30 is arranged at a position lower than the camera 40 in the vertical direction.

[0019] The camera 40 is a device that is arranged above the transport pallet 10 and images the surface (inspection surface Wa) of the work W. An image of the surface (inspection surface Wa) of the work W imaged by the camera 40 is stored in a memory (not shown). Incidentally, the size, shape, arrangement position, etc. of the bar illumination 30 and the camera 40 can be arbitrarily changed.

[0020] The bar illumination 30L on the left side in FIG. is arranged towards the reflector 20 arranged on the left side of the central work W. Also, the camera 40L on the left side in FIG. is arranged towards the side surface on the left side in the longitudinal direction of the central work W. On one hand, the bar illumination 30R on the right side in FIG. 1 is arranged towards the reflector 20 arranged on the right side of the central work W. Also, the camera 40R on the right side in FIG. 1 is arranged towards the right side surface in the longitudinal direction of the central work W.

[0021] And as shown in FIG. 1(B), the light L irradiated from the bar illumination 30 is specularly reflected by the reflector 20 (see arrow A), the light specularly reflected by the reflector 20 is specularly reflected on the surface of the work W (see arrow B), and the light specularly reflected on the surface of the work W is irradiated onto the camera 40 (see arrow C). Thereby, an image by specular reflection illumination (specular reflection light) for which it was difficult to arrange illumination can be obtained in a space-saving manner.

[0022] Note that since the light L irradiated from the bar illumination 30 is somewhat diffused, it is also irradiated onto the work W, but by adopting a light source with high linear characteristics (for example, an LED) for the bar illumination 30, a large amount of light can be irradiated onto the reflector 20.

[0023] FIG. 2 is a perspective view showing the inspection system 100 of the embodiment. In the inspection system 100, the camera 40 is arranged at the top, the bar illumination 30 is arranged below it, the work W is placed at the bottom, and the transport pallet 10 to which the reflector 20 is attached is arranged.

[0024] The transport pallet 10 is fixed on a transport conveyor (pitch conveyor) not shown and is pitch-transported. The cycle time of the pitch transport is, for example, about 1.3 seconds, and the transport conveyor repeats an intermittent operation of stopping for about 0.7 seconds and moving for about 0.6 seconds. Imaging by the camera 40 is performed during the stop time of the pitch transport. The work W is transported from the left side to the right side in the figure by pitch transport, and while the work W reaches the central position (the third position from the left side in the figure) and stops, light irradiation by the bar illumination 30 and imaging by the camera 40 are performed. The bar illumination 30 may continue to irradiate light, or may irradiate only at the timing of imaging.

[0025] Furthermore, in the example shown in Figure 2, the left and right sides of the workpiece W in the longitudinal direction are being imaged. Although not specifically shown, the front and rear sides of the workpiece W in the short direction can also be imaged in a separate process. This allows for inspection of all four sides (front, rear, left, and right) of the workpiece W.

[0026] Thus, the inspection system 100 consists of a transport pallet 10, which is a component for transporting the workpiece W and has a reflector 20 attached to it, a bar light 30 that serves as a light source, and a camera 40 that captures the light reflected from the reflector 20. The bar light 30 is positioned so that specularly reflected light is input to the camera 40 with respect to the inspection surface Wa of the workpiece W. The camera 40 then takes images of the inspection surface Wa of the workpiece W during pitch transport.

[0027] Figure 3 illustrates the necessity of specular reflection illumination images. Figure 3(A) shows a low-angle illumination image from the side, and Figure 3(B) shows a specular reflection illumination image using a reflector.

[0028] Figures 3(A) and 3(B) show images of the same workpiece W surface. The surface of workpiece W has three scratches (scratch S1, scratch S2, and scratch S3). As shown in Figure 3(A), the low-angle illumination image from the side does not utilize specular reflection, resulting in an overall dark image. Consequently, scratch S1 is almost invisible, while scratches S2 and S3 are only slightly visible. Thus, a normal lighting arrangement that does not interfere with transport may be insufficient for defect detection (scratches may not be visible or may be depicted unclearly).

[0029] On the other hand, as shown in Figure 3(B), in the image obtained using specular reflection illumination employed in the inspection system 100, the light is specularly reflected by the reflector 20 and illuminated by the camera 40, resulting in an overall bright image. Therefore, scratches S1, S2, and S3 can be clearly identified. Thus, with a specular reflection image obtained by the reflector 20 on the transport pallet 10, defect detection can be sufficiently performed (there are no cases where scratches are not captured or where the depiction is unclear). Furthermore, by using the image shown in Figure 3(B) for image judgment by an image judgment unit (not shown), a high level of defect detection is possible.

[0030] Furthermore, using the image shown in Figure 3(A) in conjunction with the specular reflection image allows for more advanced defect detection. While specular reflection images have high defect detection capabilities, and it might seem that low-angle side illumination images are unnecessary, depending on the size, length, and type of the defect, low-angle side illumination images may sometimes capture the defect more clearly (for example, if the defect S2 is shorter and thinner, it may be more clearly visible in a low-angle side illumination image).

[0031] Figure 4 shows the inspection method for the comparative example. As shown in Figure 4(A), the inspection method, which involves moving the lighting 30A and camera 40A in and out during transport, requires a mechanism (actuator, etc.) to move the lighting 30A and camera 40A, resulting in the problem of increased equipment size. Furthermore, it is not possible to obtain images through specular reflection illumination.

[0032] Furthermore, as shown in Figure 4(B), in an inspection method where the camera 40B is placed above the transport pallet 10 and the lighting 30B is placed below the transport pallet 10, it is difficult for the light from the lighting 30B to penetrate the transport pallet 10. Even if the transport pallet 10 were made transparent, the orientation of the camera 40B and lighting 30B would be reversed (the camera 40B and lighting 30B would be placed in different locations), which would result in the equipment becoming larger.

[0033] Although not specifically illustrated, there is also an inspection method in which the camera 40 is placed to the side of the transport pallet 10. However, it is still not possible to obtain an image through specular reflection, and furthermore, when the workpiece W becomes larger (when the length in the longitudinal direction becomes about 300 mm), there is a problem in that the camera 40 can no longer focus.

[0034] In contrast, in the inspection system 100 of this embodiment, both the bar lighting 30 and the camera 40 are positioned above the transport pallet 10, so the workpiece W can be imaged in the short direction and with specular reflection illumination. Compared to cases where low-angle lighting or transmitted light is used with a transparent pallet is employed, this system 100 is less expensive, saves space, and allows the camera 40 to focus more easily.

[0035] As described above, this embodiment has the following advantages. (1) According to this embodiment, since both the camera 40 and the bar lighting 30 are positioned above the transport pallet 10, an inspection system 100 that can be installed in a space-saving manner can be provided. Furthermore, according to this embodiment, since a reflector 20 is provided on the transport pallet 10, an inexpensive inspection system 100 can be provided. Moreover, according to this embodiment, since specular reflection illumination is used, an image with reduced unevenness can be captured.

[0036] (2) According to this embodiment, since the reflector 20 is attached to the transport pallet 10, it can be installed at low cost and easily, existing equipment can be reused, and it does not peel off like paint.

[0037] (3) According to this embodiment, the reflector 20 is a milky white color, so it does not absorb light and easily diffuses light, making it possible to capture a clear image.

[0038] (4) According to this embodiment, since the reflector 20 is made of resin, it is a material that easily diffuses light, and a clear image can be captured.

[0039] (5) According to this embodiment, since the bar light 30 is positioned lower than the camera 40, the amount of light from the bar light 30 can be maximized by bringing it closer to the workpiece W, and imaging can be performed with a telephoto lens (zoom lens) by moving the camera 40 further away from the workpiece W. A telephoto lens can capture distant subjects in large detail and clearly capture even fine scratches.

[0040] (6) According to this embodiment, the bar light 30 has a light-emitting surface 31 with a length L2 that is longer than the horizontal length L1 of the surface of the workpiece that the camera 40 images. By using a long bar light 30, the entire surface of the workpiece W can be thoroughly illuminated. In this embodiment, a reflector 20 for light reflection is attached to the transport pallet 10, which originally only functions as a transport device, so that it can also be used as an external inspection jig. In other words, by attaching the reflector 20 to the transport pallet 10, the transport pallet 10 itself becomes an optical component of the camera 40. This provides the following effects. (a) High-speed image inspection is possible while the workpiece W is being transported (while being transported by pitch). (b) Automated inspection is possible with a relatively inexpensive configuration. (c) Specular reflection images can be acquired by camera 40 in a confined space. (d) Small workpieces can be inspected without any problems, but it is especially suitable for inspecting large workpieces.

[0041] (7) In the visual inspection of a workpiece W on a transport pallet 10 fixed to a transport conveyor for image inspection processing while transporting large workpieces at high speed, a reflector 20 (milky white resin plate) is attached to the transport pallet 10 for inspection. As a result, it is possible to acquire images using specular reflection illumination, which was difficult to achieve with lighting arrangements.

[0042] (8) The technology described in Patent Document 1 above is a technology that uses lighting as a stage to detect indentations on the surface of a cylindrical workpiece. However, in the technology of Patent Document 1, the stage itself emits light, so the equipment is expensive. Also, in the technology of Patent Document 1, because the stage itself emits light, the light source is too close to the workpiece, resulting in unevenness in the image.

[0043] [Transformed form] The present invention can be implemented in various ways without being limited to the embodiments described above. (1) The reflective part may be provided in a location other than the upper surface of the conveying part. (2) The transport section itself may be made of a milky white resin. In this case, the transport section will have a reflective surface, so a reflector is not required.

[0044] (3) The reflective parts may be painted. If painted, it is preferable to use a milky white matte finish rather than a milky white clear finish. (4) The reflective part may be a color other than milky white (for example, white, gray, warm colors, cool colors, etc.).

[0045] (5) The reflective part does not have to be made of resin. (6) The illumination unit may be positioned at the same location as the imaging unit or at a higher location than the imaging unit in the vertical direction.

[0046] (7) The lighting unit may be a light source other than a bar light. The length of the light-emitting surface of the bar light can be set arbitrarily. (8) The images captured by the imaging unit may be used for image determination (image processing) by an image determination unit (not shown), or they may be stored in a database so that the user can check them. [Explanation of Symbols]

[0047] 10 Transport Pallets 20 Reflector 30, 30L, 30R bar lighting 30A, 30B lighting 31 Light-emitting surface 40, 40L, 40R, 40A, 40B Cameras 100 Inspection Systems L light L1 is the horizontal length of the workpiece surface. L2 Length of the light-emitting surface S1, S2, S3 scratches Double job Wa Inspection Surface

Claims

1. An inspection system for inspecting the surface of a workpiece, A transport unit for transporting the aforementioned workpiece, The reflective section provided in the transport section, An illumination unit is positioned above the transport unit and irradiates light onto the reflecting unit, It comprises an imaging unit positioned above the transport unit for imaging the surface of the workpiece, An inspection system characterized in that light emitted from the illumination unit is specularly reflected by the reflecting unit, the specularly reflected light from the reflecting unit is specularly reflected by the surface of the workpiece, and the specularly reflected light from the surface of the workpiece is emitted onto the imaging unit.

2. In the inspection system described in claim 1, The inspection system is characterized in that the reflective part is a reflector plate attached to the upper surface of the conveying part.

3. In the inspection system described in claim 1, The inspection system is characterized in that the reflective part is of a milky white color.

4. In the inspection system described in claim 1, The inspection system is characterized in that the reflective part is made of resin.

5. In the inspection system described in claim 1, The inspection system is characterized in that the illumination unit is positioned lower than the imaging unit in the vertical direction.

6. In the inspection system described in claim 1, The inspection system is characterized in that the illumination unit is a bar illumination unit having a light-emitting surface longer than the horizontal length of the surface of the workpiece captured by the imaging unit.

Images