Inspection system, inspection method, and belt conveyor

Abstract

This inspection system S is for inspecting an inspection target W, and comprises: a belt conveyor C that conveys the inspection target W by moving a flexible belt B on which the inspection target W is placed and that has a transparent region for light transmission; a first imaging device 11 that is installed on the opposite side to the side on which the inspection target W is placed on the belt B and captures an image of the inspection target W through the transparent region; and an inspection device 2 that inspects the inspection target W on the basis of a first captured image generated by the first imaging device 11.

Description

Inspection System, Inspection Method, and Belt Conveyor

[0001] The present invention relates to an inspection system, an inspection method, and a belt conveyor for inspecting an object to be inspected.

[0002] Conventionally, a defect inspection apparatus is known that irradiates a sample made of a glass substrate such as a semiconductor wafer or a flat display (FPD) with illumination light, captures the light from the sample at this time, and inspects for defects on the back surface of the sample from the image data (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2008-203280

[0004] However, the technique described in Patent Document 1 has a problem that the inspection efficiency is poor because it is necessary to set the samples one by one on the holding member.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to improve the efficiency of inspecting the lower surface (back surface) of an object to be inspected.

[0006] An inspection system according to a first aspect of the present invention is an inspection system for inspecting an object to be inspected, comprising: a belt conveyor that conveys the object to be inspected by moving a flexible belt having a transparent region on which the object to be inspected is placed and through which light is transmitted; a first imaging device that is installed on the side of the belt opposite to the side on which the object to be inspected is placed and that captures an image of the object to be inspected through the transparent region; and an inspection device that inspects the object to be inspected based on a first captured image generated by the first imaging device.

[0007] The optical characteristics in the transparent region may fall within a predetermined range regardless of the location of the transparent region.

[0008] The first imaging device may capture an image of a correction tool placed on the transparent region for correcting the first captured image, and the inspection device may correct the first captured image based on correction data created based on the image of the captured correction tool and inspect the object to be inspected.

[0009] The inspection system may further include a placement device that, when dirt is detected in the transparent area by imaging with the first imaging device, places the object to be inspected in a location within the transparent area other than the location where the dirt was detected.

[0010] The inspection system may further include a placement device for placing the object to be inspected in the transparent area such that the position of the object in the transparent area on which the object is placed changes with each predetermined number of placements.

[0011] The inspection system may further include a placement device for placing the object to be inspected, which is wrapped in transparent packaging, onto the transparent area.

[0012] The inspection system may further include a cleaning device for cleaning the surface on which the object to be inspected is placed within the transparent area.

[0013] The inspection system is installed on the side of the belt on which the object to be inspected is placed, and may further include a cutting device for cutting the object to be inspected.

[0014] A marker indicating deformation of the transparent region may be provided in the transparent region, the first imaging device may image the object to be inspected through the transparent region on which the marker is provided, and the inspection device may inspect the state of the object to be inspected based on the image of the marker shown in the first image generated by the first imaging device.

[0015] The inspection device may also inspect the condition of the object to be inspected by referring to data that associates the amount of change in the shape of the marker with the magnitude of the pressure applied to the marker, and by identifying the pressure associated with the amount of change that indicates the change from the shape of the marker in the image when the object to be inspected is not placed on the transparent area of ​​the belt to the shape of the marker in the image when the object to be inspected is placed on the transparent area of ​​the belt.

[0016] The inspection device may inspect the condition of the object to be inspected by referring to data that associates the amount of movement of the marker position with the magnitude of the pressure applied to the marker, and by identifying the amount of movement and associated pressure that indicates the movement of the object to be inspected from the position of the marker in the image when the object to be inspected is not placed on the transparent area of ​​the belt to the position of the marker in the image when the object to be inspected is placed on the transparent area of ​​the belt.

[0017] The inspection system is installed on the side of the belt on which the object to be inspected is placed, and may further include a second imaging device for imaging the object to be inspected. The inspection device may determine the volume of the object to be inspected based on the surface area of ​​the object to be inspected identified based on a first image generated by the first imaging device, the surface area of ​​the object to be inspected identified based on a second image generated by the second imaging device, and the height of the object to be inspected identified based on the first or second image.

[0018] The inspection device may determine the weight of the object to be inspected by multiplying the weight per unit volume of the object to be inspected by the volume of the object to be inspected, which has been identified.

[0019] A second aspect of the present invention relates to an inspection method for inspecting an object to be inspected, comprising the steps of: transporting the object to be inspected by a belt conveyor on which a flexible belt having a transparent region on which the object to be inspected is placed and which transmits light moves; imaging the object to be inspected by a first imaging device installed on the opposite side of the belt from the side on which the object to be inspected is placed, through the transparent region; and inspecting the object to be inspected based on a first image generated by the first imaging device.

[0020] A third aspect of the present invention provides a belt conveyor that transports an object to be inspected by moving a flexible belt on which the object to be inspected is placed and which has a transparent region that transmits light.

[0021] The present invention has the effect of improving the efficiency of inspecting the underside of an object being inspected.

[0022] This is a side view of the belt conveyor C. This is a top view of the belt conveyor C. This is a diagram showing an example of a judgment result table. This is a diagram showing an example of changing the placement location of the object to be inspected W. This is a diagram showing an example of a marker M provided on belt B. This is a diagram showing an example of a first imaging device 11 installed so that the angle X formed by the optical axis OA and the plane containing the inspection area KR is 45 degrees. This is a diagram showing an example of a reference image and a comparison image. This is a diagram showing an example of correction data. This is a diagram showing an example of installing multiple imaging devices. This is a diagram showing an example of a volume calculation formula table. This is a flowchart showing the processing flow in the inspection device 2.

[0023] <First Embodiment: Basic Configuration of Inspection System S> [Overview of Inspection System S] Figures 1 and 2 are diagrams illustrating an overview of an example of Inspection System S. Figure 1 is a side view of the belt conveyor C of Inspection System S. Figure 2 is a top view of the belt conveyor C. Inspection System S is a system for inspecting objects. The objects to be inspected are not particularly limited, but for example, they may be food products, specifically sweets, fungi (mushrooms, etc.), vegetables, fruits, or pieces of meat.

[0024] When inspecting objects for scratches, dirt, dents, etc., there is a demand to be able to inspect the contact surface (underside) of the object placed on the conveyor belt. However, inspecting the underside of an object required lifting the object off the conveyor belt or changing its orientation to allow for imaging or observation of the underside, which resulted in poor inspection efficiency.

[0025] Therefore, in the inspection system S, a transparent area is provided on the belt of the conveyor belt, and an imaging device images the underside of the object to be inspected placed in the transparent area. This makes it possible to image the underside of the object to be inspected without lifting or changing the orientation of the object, thus enabling efficient inspection of the underside of the object.

[0026] The inspection system S comprises a belt conveyor C, a first imaging device 11, an inspection device 2, a placement device 3, and a cleaning device 4. In the inspection system S shown in Figure 1, the placement device 3 and the cleaning device 4 are provided, but these two devices are not essential in the present invention.

[0027] Belt conveyor C is a device for transporting objects W to be inspected. Belt conveyor C has a flexible belt B on which the objects W to be inspected are placed and which has a transparent area through which light is transmitted, and rollers R for moving belt B. The transparent area may be a plurality of rectangular areas formed on belt B, or a part of the belt B, such as the central area excluding the vicinity of the long sides when belt B is viewed from above, but in the following explanation, the entire belt B will be described as a transparent area.

[0028] The first imaging device 11 is a device that generates a first image by imaging the object to be inspected W, and is, for example, a camera. The first imaging device 11 can transmit the first image data showing the first image to the inspection device 2. The first imaging device 11 is installed in a position where it can image the lower surface of the object to be inspected W, and is, for example, installed on the side of the belt B opposite to the side on which the object to be inspected W is placed.

[0029] The first imaging device 11 images the underside of the object to be inspected W via the belt B, but the first image generated by the first imaging device 11 is affected by the optical properties (such as light transmission, reflection, refraction, or absorption) of the transparent region of the belt B. In order to perform inspections with higher accuracy, it is preferable to minimize the influence of the optical properties of the belt B. Therefore, as shown in Figure 1, the first imaging device 11 may be installed between the upper belt BU, which is located above the roller R and transports the object to be inspected W, and the lower belt BL, which is located below the roller R and moves the upper belt in the opposite direction to the transport direction of the object to be inspected W. In this way, the first imaging device 11 can image the object to be inspected W via the upper belt BU without going through the lower belt BL on the belt B, and thus the influence of the optical properties of the transparent region of the belt B can be minimized compared to when the object to be inspected W is imaged via both the upper belt BU and the lower belt BL.

[0030] The inspection device 2 is a device that inspects the object to be inspected W based on the first image generated by the first imaging device 11, and includes, for example, a computer. The placement device 3 is a device that places the object to be inspected W on a transparent area on the belt conveyor C, and is, for example, a robot arm. The cleaning device 4 is a device that cleans the surface on which the object to be inspected W is placed, and is, for example, a wiper, mop, cloth, or a device that discharges liquid or gas. Below, an example of the basic operation of the inspection system S will be described with reference to Figures 1 and 2.

[0031] The object to be inspected W, placed on the transparent belt B of the belt conveyor C by the placement device 3, is transported by the belt B toward the area where the first imaging device 11 images the object to be inspected W (i.e., the inspection area KR). When the object to be inspected W reaches the position of the inspection area KR as shown in Figure 2, the first imaging device 11 images the underside of the object to be inspected W via the transparent belt B.

[0032] The first imaging device 11 transmits first image data, which shows the first image generated by imaging the object W to be inspected, to the inspection device 2. Based on the first image generated by the first imaging device 11, the inspection device 2 inspects the underside of the object W to be inspected for scratches, dirt, dents, etc.

[0033] The area on belt B where the object to be inspected W is placed may become contaminated. As described above, the first imaging device 11 images the underside of the object to be inspected W via belt B, so if belt B is contaminated, the contaminated area of ​​belt B will be included in the first image, which may reduce the accuracy of the inspection by the inspection device 2. For this reason, the cleaning device 4 cleans belt B, for example, immediately before the placement device 3 places the object to be inspected W onto belt B.

[0034] [Configuration of Belt Conveyor C] Belt conveyor C comprises a flexible belt B having a transparent region and rollers R for moving belt B. Belt conveyor C may have a plate-like member between the upper belt BU and the lower belt BL to support the upper belt BU. In this case as well, belt conveyor C does not have a plate-like member directly below the inspection region KR on belt B so that the first imaging device 11 can image the object to be inspected W. The plate-like member may have an opening formed therein that corresponds to the imaging region of the first imaging device 11.

[0035] The transparent region of belt B is the region on which the object to be inspected W is placed, and is also a region through which light is transmitted. The light transmittance in the transparent region is, for example, 80% or more. An example of a transparent material that can be used for the transparent region is polyvinyl chloride (PVC), which is used in greenhouses and vinyl curtains. When transparent regions are formed by joining transparent materials together, it is preferable that the seam portion has the same degree of transparency as the rest of the material (i.e., is seamless). This allows the inspection device 2 to perform inspections with high accuracy even when the first captured image includes the seam portion between the transparent materials.

[0036] If the uneven shape or thickness differs in each part of the transparent region, the optical properties of each part of the transparent region will also differ. As a result, the inspection results of the inspection device 2 may differ depending on which part of the transparent region is used to image the object W being inspected (i.e., variations in the inspection results may occur). For this reason, it is preferable that the optical properties of the transparent region of the belt B fall within a predetermined range, regardless of its location within the transparent region. For example, it is preferable that the optical property values ​​(such as light transmittance, reflectance, refractive index, or absorptance) corresponding to each of the multiple parts of the transparent region fall within a predetermined range. By keeping the optical properties of each part of the transparent region within a predetermined range in this way, variations in the inspection results of the inspection device 2 can be suppressed.

[0037] [Configuration of the Imaging Device] The first imaging device 11 images the object to be inspected W through the transparent region of the belt B. For example, when the entire object to be inspected W enters the inspection region KR on the belt B, the first imaging device 11 generates a first image by imaging the contact surface (bottom surface) of the object to be inspected W that is in contact with the belt B.

[0038] [Configuration of Inspection Device 2] Inspection device 2 inspects the object to be inspected W based on the first image generated by the first imaging device 11. For example, inspection device 2 inspects at least one of the volume, weight, shape, and scratches / stains of the object to be inspected W based on the first image shown by the first image data received from the first imaging device 11. Specifically, inspection device 2 inspects at least one of the volume, weight, shape, and scratches / stains of the object to be inspected W by comparing the first image data with normal image data that shows the appearance of a normal object to be inspected W, which has been generated in advance and stored on a storage medium. Inspection device 2 determines that the object to be inspected W is not normal if the difference between the first image data and the normal image data is greater than or equal to the threshold corresponding to volume, weight, shape, and scratches / stains, respectively.

[0039] The inspection device 2 generates a judgment result table showing the results for each item of the identified object W to be inspected, such as volume, weight, shape, and scratches / stains, as well as the judgment result regarding whether the object W to be inspected can be shipped. For example, if the object W to be inspected passes all of the aforementioned items, the inspection device 2 gives a "pass" judgment result indicating that the object W to be inspected can be shipped. If the object W to be inspected fails at least one of the aforementioned items, the inspection device 2 gives a "fail" judgment result indicating that the object W should not be shipped.

[0040] Figure 3 shows an example of a judgment result table. In the judgment result table, an ID for identifying the object to be inspected W, the volume of the object to be inspected W, the weight of the object to be inspected W, the judgment result regarding the shape of the object to be inspected W, the presence or absence of scratches or stains on the object to be inspected W, and the judgment result regarding whether the object to be inspected W is shippable or not are associated. The inspection device 2 may transmit the generated judgment result table to a sorting device that sorts the objects to be inspected W into shippable and non-shippable items. This allows the sorting device to sort the objects to be inspected W whose judgment result regarding shippable or not is "pass" into shippable items, and to sort the objects to be inspected W whose judgment result regarding shippable or not is "fail" into non-shippable items.

[0041] [Configuration of the Placement Device 3] During the process of the belt B transporting the object to be inspected W, the transparent area of ​​the belt B may become contaminated. In particular, if the object to be inspected W is food, the transparent area is more likely to become contaminated. If the transparent area becomes contaminated, the first captured image may contain the contaminated material, which may result in a decrease in the accuracy of the inspection results obtained by the inspection device 2. Therefore, the placement device 3 may place the object to be inspected W, which is wrapped in transparent packaging, onto the transparent area.

[0042] The material of the transparent wrapping paper is, for example, the same material used for plastic wrap, but it can also be the same material as the transparent material of belt B mentioned above. By wrapping the object to be inspected W in transparent wrapping paper in this way, contamination of the transparent area can be suppressed, and thus the accuracy of the inspection results by the inspection device 2 can be suppressed.

[0043] If it is not possible to wrap the objects to be inspected W in packaging paper due to reasons such as the presence of a large quantity of objects to be inspected W, the transparent area of ​​the belt B may become contaminated. In order to prevent a decrease in the accuracy of the inspection results by the inspection device 2 in such cases, the placement device 3 may place the objects to be inspected W in the transparent area on which they are placed such that the position of the objects to be inspected W changes every predetermined number of placements.

[0044] FIG. 4 is a diagram showing an example of changing the placement position of the inspection object W. For example, as shown in FIG. 4(a), the placement device 3 places the inspection object W in the region indicated by the slanted lines in the first placement, and places the inspection object W in the region indicated by the halftone dots in the second placement. By shifting the timing of the placement, the placement position of the inspection object W is changed. As shown in FIG. 4(b), the placement device 3 places the inspection object W in the central region R1 of both long sides when looking at the belt B from above in the first placement, places the inspection object W in the region R2 closer to one long side than the central region R1 in the second placement, and places the inspection object W in the region R3 closer to the other long side than the central region R1 in the third placement. The placement position of the inspection object W may be changed by shifting the placement location.

[0045] In this way, by placing the inspection object W so that dirt is less likely to accumulate in the transparent region or by placing the inspection object W at a position where there is no dirt, the probability that the first captured image contains dirt can be reduced. As a result, it is possible to suppress a decrease in the accuracy of the inspection result by the inspection device 2.

[0046] [Configuration of the cleaning device 4] Even if the method of placing the inspection object W is devised as described above, since there is a limit to the place where the inspection object W can be placed, the number of places without dirt will ultimately decrease. Therefore, the cleaning device 4 cleans the surface on which the inspection object W is placed in the transparent region. For example, as shown in FIG. 1, the cleaning device 4 cleans the transparent region immediately before the placement device 3 places the inspection object W in the transparent region (that is, upstream of the belt conveyor C). The cleaning device 4 may clean the transparent region immediately after a sorting device that sorts the inspection object W into shipped products and non-shipped products sorts the inspection object W (that is, downstream of the belt conveyor C). The cleaning device 4 may clean the transparent region by wiping off the dirt with a wiper, mop or cloth, or may clean the transparent region by discharging a liquid or gas and blowing it onto the dirt.

[0047] [Effect of the inspection system S] As described above, the inspection system S includes a belt conveyor C that conveys the inspection object W by moving a flexible belt B having a transparent region on which the inspection object W is placed and through which light passes, a first imaging device 11, and an inspection device 2 that inspects the inspection object W based on a first captured image generated by the first imaging device 11. Thereby, since the inspection object W can be inspected based on an image of the lower surface of the inspection object W while the inspection object W is being conveyed by the belt conveyor C, the efficiency of the inspection is improved.

[0048] Further, in the inspection system S, since it is only necessary to place the inspection object W on the belt conveyor C, unlike in the above Patent Document 1, it is not necessary to set the inspection objects W one by one on the holding members. As a result, the inspection can be performed efficiently, and the types of the inspection objects W are not limited to those that can be set on the holding members.

[0049] <Configuration of the inspection system S in which the marker M is provided on the belt B in the second embodiment> Next, a second embodiment of the present invention will be described. The second embodiment can be the same as the first embodiment except for the points described below. Therefore, except for the points described below, the basic structure of the inspection system may be as shown in FIGS. 1 and 2.

[0050] In the second embodiment, since the belt B is a flexible material as described above, when the inspection object W is placed on the belt B, the shape of the belt B changes. Therefore, in order to detect this change in shape, a marker M indicating the deformation of the transparent region may be provided in the transparent region of the belt B. By providing the marker M in the transparent region in this way, although details will be described later, it becomes possible to inspect the weight, the shape of the lower surface, etc. of the inspection object W based on the image of the marker M shown in the first captured image.

[0051] Figure 5 shows an example of markers M provided on belt B. Belt B shown in Figure 5 is provided with a dot pattern in which multiple circular markers M are arranged in a grid at predetermined intervals. The shape of the markers M is not limited to circles, and may be polygonal, cross-shaped, star-shaped, etc. Also, the arrangement pattern of the markers M is not limited to a dot pattern, and may be a stripe-shaped pattern in which multiple lines are arranged in parallel, or a grid-shaped pattern in which multiple vertical lines and multiple horizontal lines are arranged to intersect.

[0052] The first imaging device 11 may generate a first image showing the marker M by imaging the object to be inspected W through a transparent region on which a marker M indicating deformation of the transparent region is provided. The first imaging device 11 transmits the first image data showing the generated first image to the inspection device 2.

[0053] The first imaging device 11 is installed in such a orientation that the angle between the optical axis of the first imaging device 11 and the plane containing the inspection area KR on belt B is a predetermined angle (for example, 45 degrees). Figure 6 shows an example of the first imaging device 11 installed so that the angle X between the optical axis OA and the plane containing the inspection area KR is 45 degrees. As a result, when the first imaging device 11 images the object to be inspected W in the inspection area KR, the marker M is imaged from diagonally below, making it easier to identify changes in the shape and movement of the marker M compared to when the marker M is imaged from directly below.

[0054] The inspection device 2 may inspect the state of the object to be inspected W based on the image of the marker M shown in the first image generated by the first imaging device 11. For example, the inspection device 2 identifies an amount of change indicating the change from the shape of the marker M when the object to be inspected W is not placed on the transparent area of ​​the belt B to the shape of the marker M when the object to be inspected W is placed on the transparent area of ​​the belt B. The inspection device 2 also identifies an amount of movement indicating the movement of the marker M from the position of the marker M when the object to be inspected W is not placed on the transparent area of ​​the belt B to the position of the marker M when the object to be inspected W is placed on the transparent area of ​​the belt B.

[0055] The inspection device 2, for example, refers to data that associates the amount of change in shape or the amount of displacement of marker M with the magnitude of the pressure applied to marker M, identifies the pressure associated with the identified amount of change or displacement, and determines the weight of the object to be inspected W based on the identified pressure. Alternatively, the inspection device 2 may identify the pressure applied to each of the multiple markers M by identifying the amount of change in shape or the amount of displacement of the multiple markers M, and determine the shape of the lower surface of the object to be inspected W based on the identified pressure.

[0056] In this way, the inspection device 2 can accurately determine the weight or shape of the underside of the object W by inspecting the state of the object W based on the image of the marker M shown in the first captured image.

[0057] If dirt is detected in a transparent area by the first imaging device 11, the placement device 3 may place the object to be inspected W at a location within the transparent area other than the location where the dirt was detected. As described above, the location of the transparent area shown in the first image can be identified by providing a mark to identify the location in the transparent area or by attaching an identification code to the marker M. The inspection device 2, for example, identifies the location of the transparent area shown in the image in which dirt was detected among the images captured by the first imaging device 11, and transmits placement control data to the placement device 3 to operate the placement device 3 to place the object to be inspected W at a location other than the identified location. The placement device 3 can place the object to be inspected W at a location other than the location where dirt was detected by operating the object to be inspected W according to the received placement control data.

[0058] By the way, cleaning areas without dirt in the transparent region would waste power and accelerate the deterioration of the cleaning device 4. Therefore, the inspection device 2 identifies the location of the transparent region indicated by the image in which dirt is detected among the images captured by the first imaging device 11, and transmits cleaning control data to the cleaning device 4 to operate it to clean the identified location. By operating according to the received cleaning control data, the cleaning device 4 can clean the areas with dirt and not clean the areas without dirt. In this way, the power consumption required for inspecting the object W can be reduced, and the deterioration of the cleaning device 4 can be slowed down.

[0059] <Third Embodiment: Configuration of Inspection System S when Correcting Captured Images> Next, a third embodiment of the present invention will be described. The third embodiment can be the same as the first embodiment except for the points described below. Therefore, except for the points described below, the basic structure of the inspection system can be as shown in Figures 1 and 2.

[0060] Over time, the transparent area of ​​belt B may become distorted or discolored due to deterioration. As a result, the inspection results may differ depending on which part of the transparent area the first imaging device 11 uses to image the object W being inspected. Therefore, the first imaging device 11 may image a correction device placed on the transparent area for correcting the first image. The correction device is, for example, a checkerboard used for camera calibration. The correction device may have, for example, a grid of straight lines drawn on a white background.

[0061] The first imaging device 11 generates, for example, a reference image of a corrective device placed on a transparent area of ​​the belt B immediately after manufacturing, which is free from distortion and discoloration, and a comparison image of a corrective device placed on a transparent area of ​​the belt B after a certain number of inspection objects W have been transported.

[0062] Figure 7 shows an example of a reference image and a comparison image. Figure 7(a) shows a reference image of the checkerboard CK taken when belt B is free from distortion and discoloration. Figure 7(b) shows a comparison image of the checkerboard CK taken when belt B is distorted and discolored. In Figure 7(b), the shaded area D indicates the area of ​​discoloration on belt B. In Figure 7(b), the images of the left two columns of the checkerboard CK are distorted because belt B is distorted.

[0063] The first imaging device 11 transmits comparison data showing the generated reference image and comparison image to the inspection device 2. This allows the inspection device 2 to create correction data for correcting the first captured image, as described below.

[0064] For example, the inspection device 2 calculates a distortion correction formula and a color correction additive value to make the area, shape, and brightness values ​​of the correction device shown in the comparison image the same as the area, shape, and brightness values ​​of the correction device shown in the reference image, based on the reference image and the comparison image shown by the comparison data received from the first imaging device 11. The inspection device 2 stores the calculated distortion correction formula and color correction additive value as correction data.

[0065] Figure 8 shows an example of correction data. In the correction data, the identification information of the transparent area, the formula for distortion correction, and the additive value for color correction are associated. Distortion and discoloration of the transparent area may differ depending on the location. Therefore, a mark may be placed in the transparent area to identify its location, or an identification code may be attached to the marker M. This makes it possible to identify the location of the transparent area shown in the first captured image generated by the first imaging device 11, and as shown in Figure 8, it becomes possible to manage the formula for distortion correction and the additive value for color correction for each part of the transparent area.

[0066] The inspection device 2 may generate a corrected image by substituting the coordinates of pixels included in the first captured image showing the object to be inspected W into a distortion correction formula and adding a color correction additive value to the pixel values ​​of the pixels included in the first captured image. Then, the inspection device 2 inspects the object to be inspected W based on the generated corrected image. By correcting the first captured image showing the object to be inspected W in this way, the inspection device 2 can maintain a constant level of accuracy in inspection even if the transparent area becomes distorted or discolored over time. Furthermore, by managing the distortion correction formula and the color correction additive value for each part of the transparent area, the inspection device 2 can maintain a constant level of accuracy in inspection even if the distortion or discoloration of the transparent area differs depending on the part.

[0067] Since the first imaging device 11 images the object to be inspected W through the transparent region of the belt B, it is affected by the optical properties of the transparent region, as described above. The inspection device 2 may correct the first image to suppress this effect and then inspect the object to be inspected W. For example, the inspection device 2 calculates a distortion correction formula and a color correction additive value based on the image obtained by the first imaging device 11 without using the transparent region and the image obtained by the first imaging device 11 through the transparent region. Then, for example, the inspection device 2 inspects the object to be inspected W based on a corrected image obtained by correcting the first image generated by the first imaging device 11 using the calculated distortion correction formula and color correction additive value. In this way, the effect of the optical properties of the transparent region can be suppressed.

[0068] Furthermore, the method of correction to suppress the influence of the optical properties of the transparent wrapping paper that encloses the object to be inspected W is the same as the method of correction described in the previous paragraph to suppress the influence of the optical properties of the transparent region in belt B.

[0069] <Fourth Embodiment: Configuration of Inspection System S Equipped with Multiple Imaging Devices> Next, a fourth embodiment of the present invention will be described. The fourth embodiment can be the same as the first embodiment except for the points described below. Therefore, except for the points described below, the basic structure of the inspection system may be as shown in Figures 1 and 2.

[0070] When it is necessary to inspect the volume or weight of an object W to be inspected, it may be easier to inspect the object W if it is imaged from angles other than those captured by the first imaging device 11. Therefore, the inspection system S may further include at least one of a second imaging device 12 and a third imaging device 13, which are installed on the side of the belt B where the object W to be inspected is placed and which image the object W to be inspected.

[0071] Figure 9 shows an example of a setup with multiple imaging devices. In the example shown in Figure 9, the first imaging device 11 images the underside of the object W to be inspected, the second imaging device 12 images the top surface of the object W to be inspected, and the third imaging device 13 images the side surface of the object W to be inspected.

[0072] The second imaging device 12 is installed, for example, at a height higher than the height at which the object to be inspected W is located, and generates a second image by imaging the surface (top surface) of the object to be inspected W that is opposite to the surface (bottom surface) that is in contact with the belt B. The second imaging device 12 transmits the second image data showing the generated second image to the inspection device 2.

[0073] The third imaging device 13 is installed, for example, at a height approximately the same as the height at which the object to be inspected W is located, and generates a third image by imaging the side surface of the object to be inspected W, which is a surface other than the bottom and top surface. The third imaging device 13 transmits the third image data showing the generated third image to the inspection device 2.

[0074] By imaging the object W from multiple angles in this way, it becomes easier to determine the volume and weight of the object W, and also easier to identify scratches and dirt present on surfaces other than the bottom surface of the object W. In the example shown in Figure 9, one first imaging device 11, one second imaging device 12, and one third imaging device 13 are installed, but there is no particular limit to the number of each imaging device that can be installed.

[0075] The inspection device 2 may determine the volume or weight of the object to be inspected W based on images generated by multiple imaging devices. The inspection device 2 determines the surface area of ​​the object to be inspected W based on a first image generated by the first imaging device 11. The inspection device 2 determines, for example, the area on the surface of the object to be inspected W that can be identified from the first image (for example, the area of ​​the bottom surface of the object to be inspected W). The inspection device 2 also determines the surface area of ​​the object to be inspected W based on a second image generated by the second imaging device 12. The inspection device 2 determines, for example, the area on the surface of the object to be inspected W that can be identified from the second image (for example, the area of ​​the top surface of the object to be inspected W). The inspection device 2 determines the height of the object to be inspected W based on the first or second image. The inspection device 2 may determine the height of the object to be inspected W based on a third image generated by the third imaging device 13.

[0076] The inspection device 2 determines the volume of the object to be inspected W based on the surface area (e.g., the area of ​​the bottom surface) of the object to be inspected W identified based on the first image, the surface area (e.g., the area of ​​the top surface) of the object to be inspected W identified based on the second image, and the height of the object to be inspected W identified based on the first or second image. The inspection device 2 determines the volume of the object to be inspected W, for example, by substituting the area of ​​the bottom surface, the area of ​​the top surface, and the height of the object to be inspected W into a volume calculation formula corresponding to the type of object of the object to be inspected W. The inspection device 2 may store a volume calculation formula table in order to identify the volume calculation formula.

[0077] Figure 10 shows an example of a volume calculation formula table. In the volume calculation formula table, the object type and the volume calculation formula are associated. The inspection device 2 can identify the volume calculation formula corresponding to the object type of the object to be inspected W by referring to the volume calculation formula table.

[0078] The inspection device 2 may determine the weight of the object to be inspected W by multiplying the weight (density) per unit volume of the object to be inspected W by the volume of the identified object to be inspected W. In this way, the volume or weight of the object to be inspected W identified by the inspection device 2 based on images generated by multiple imaging devices is a highly reliable value. As a result, for example, if the object to be inspected W is a food product such as vegetables or fruits, the weight or volume of the food product per package, which is the unit sold to consumers, can be kept constant.

[0079] <Fifth Embodiment: Configuration of Inspection System S Equipped with Cutting Device> Next, a fifth embodiment of the present invention will be described. The fifth embodiment can be the same as the first embodiment except for the points described below. Therefore, except for the points described below, the basic structure of the inspection system may be as shown in Figures 1 and 2.

[0080] In some cases, it is desirable to place an uncut mass of meat or the like on a belt conveyor C and then inspect the meat pieces created by cutting the placed mass. Therefore, in the fifth embodiment, the inspection system S is installed on the side of the belt B where the object to be inspected W is placed, and may further include a cutting device for cutting the object to be inspected W. The cutting device is installed, for example, between the placement device 3 and the first imaging device 11 in the transport direction of the belt B.

[0081] Conventionally, when the imaging device for imaging the object to be inspected is installed on the side on which the object to be inspected is placed, the cutting device may enter the imaging area of ​​the imaging device and interfere with imaging. In the inspection system S, as described above, the first imaging device 11 is installed on the opposite side of the belt B from the side on which the object to be inspected W is placed, so the cutting device does not interfere with imaging by the first imaging device 11.

[0082] [Processing flow in inspection device 2] Figure 11 is a flowchart showing the processing flow in inspection device 2. Inspection device 2 acquires a first image by receiving first image data showing the object to be inspected W from the first imaging device 11 (S1). Inspection device 2 generates a corrected image by correcting the acquired first image using correction data (S2). Inspection device 2 identifies the volume, weight, shape, and scratches / stains of the object to be inspected W based on the generated corrected image (S3).

[0083] The inspection device 2 determines whether the volume of the object to be inspected W, identified in S3, is within a predetermined range corresponding to the type of object to be inspected W (S4). If the inspection device 2 determines that the volume of the object to be inspected W is not within the predetermined range (S4: NO), the inspection device 2 determines that the object to be inspected W is unsuccessful in the inspection (S5).

[0084] On the other hand, if the inspection device 2 determines that the volume of the object to be inspected W is within a predetermined range (S4: YES), the inspection device 2 determines whether the weight of the object to be inspected W, as identified in S3, is within a predetermined range corresponding to the type of object to be inspected W (S6). If the inspection device 2 determines that the weight of the object to be inspected W is not within the predetermined range (S6: NO), the inspection device 2 determines that the object to be inspected W has failed the inspection (S5).

[0085] On the other hand, if the inspection device 2 determines that the weight of the object to be inspected W is within a predetermined range (S6: YES), the inspection device 2 determines whether the degree of agreement between the shape of the object to be inspected W identified in S3 and the ideal shape corresponding to the type of object to be inspected W is above a threshold (for example, 90%) (S7). If the inspection device 2 determines that the degree of agreement between the shape of the object to be inspected W and the ideal shape is below the threshold and that the shape of the object to be inspected W is not normal (S7: NO), the inspection device 2 determines that the object to be inspected W has failed the inspection (S5).

[0086] On the other hand, if the inspection device 2 determines that the degree of agreement between the shape of the object W and the ideal shape is above a threshold and that the shape of the object W is normal (S7: YES), the inspection device 2 determines whether the scratches and stains on the object W identified in S3 are of a size that can be seen by a person (S8). If the inspection device 2 determines that the scratches and stains on the object W are of a size that can be seen by a person and that there are scratches and stains (S8: NO), the inspection device 2 determines that the object W has failed the inspection (S5).

[0087] On the other hand, if the inspection device 2 determines that there are no visible scratches or stains on the object W being inspected (S8: YES), the inspection device 2 determines that the object W is acceptable (S9).

[0088] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combinations are combined with the effects of the original embodiments.

[0089] 11 First imaging device 12 Second imaging device 13 Third imaging device 2 Inspection device 3 Placement device 4 Cleaning device C Belt conveyor B Belt R Roller M Marker W Object to be inspected S Inspection system

Claims

1. An inspection system for inspecting an object to be inspected, comprising: a belt conveyor that transports the object to be inspected by the movement of a flexible belt on which the object to be inspected is placed and which has a transparent area through which light is transmitted; a first imaging device installed on the opposite side of the belt from the side on which the object to be inspected is placed, and which images the object to be inspected through the transparent area; and an inspection device that inspects the object to be inspected based on a first image generated by the first imaging device.

2. The inspection system according to claim 1, wherein the optical properties in the transparent region are within a predetermined range regardless of the location of the transparent region.

3. The inspection system according to claim 1, wherein the first imaging device images a correction device placed on the transparent area for correcting the first image, and the inspection device corrects the first image based on correction data created based on the image of the correction device that was imaged, and inspects the object to be inspected.

4. The inspection system according to claim 1, further comprising a placement device for placing the object to be inspected in a location within the transparent area other than the location where the dirt was detected when imaging by the first imaging device.

5. The inspection system according to claim 1, further comprising a placement device for placing the object to be inspected in the transparent area such that the position of the object to be inspected in the transparent area changes with each predetermined number of placements.

6. The inspection system according to claim 1, further comprising a placement device for placing the object to be inspected, which is wrapped in transparent packaging paper, onto the transparent area.

7. The inspection system according to claim 1, further comprising a cleaning device for cleaning the surface on which the object to be inspected is placed in the transparent area.

8. The inspection system according to claim 1, further comprising a cutting device installed on the side of the belt on which the object to be inspected is placed, for cutting the object to be inspected.

9. The inspection system according to claim 1, wherein a marker indicating deformation of the transparent region is provided in the transparent region, the first imaging device images the object to be inspected through the transparent region on which the marker is provided, and the inspection device inspects the state of the object to be inspected based on the image of the marker shown in the first image generated by the first imaging device.

10. The inspection system according to claim 9, wherein the inspection device inspects the state of an object by referring to data relating the amount of change in the shape of the marker and the magnitude of the pressure applied to the marker, and identifying the pressure associated with the amount of change indicating the change from the shape of the marker in the image when the object to be inspected is not placed on the transparent area of ​​the belt to the shape of the marker in the image when the object to be inspected is placed on the transparent area of ​​the belt.

11. The inspection system according to claim 9, wherein the inspection device inspects the state of an object by referring to data relating the amount of movement of the marker position and the magnitude of the pressure applied to the marker, and identifying a pressure associated with an amount of movement indicating the movement of the object to be inspected from the position of the marker in the image when the object to be inspected is not placed on the transparent area of ​​the belt to the position of the marker in the image when the object to be inspected is placed on the transparent area of ​​the belt.

12. The inspection system according to claim 1, wherein the inspection system is installed on the side of the belt on which the object to be inspected is placed and further comprises a second imaging device for imaging the object to be inspected, the inspection device determines the volume of the object to be inspected based on the surface area of ​​the object to be inspected determined based on a first image generated by the first imaging device, the surface area of ​​the object to be inspected determined based on a second image generated by the second imaging device, and the height of the object to be inspected determined based on the first image or the second image.

13. The inspection system according to claim 12, wherein the inspection device determines the weight of the object to be inspected by multiplying the weight per unit volume of the object to be inspected by the volume of the object to be inspected which has been identified.

14. An inspection method for inspecting an object to be inspected, comprising: a step of transporting the object to be inspected by a belt conveyor on which a flexible belt having a transparent region on which the object to be inspected is placed and which has a light-transmitting transparent region moves; a step of imaging the object to be inspected by a first imaging device installed on the opposite side of the belt from the side on which the object to be inspected is placed, through the transparent region; and a step of inspecting the object to be inspected by an inspection device based on a first image generated by the first imaging device.

15. A belt conveyor that transports an object to be inspected by moving a flexible belt on which the object to be inspected is placed and which has a transparent area that transmits light.

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