Imaging device

Abstract

To provide an imaging device which can properly capture an image of an article covered by a packaging film.SOLUTION: An imaging device comprises: a light source; a diffuser plate; and a camera. The light source is provided on the outer side with respect to the outermost contour of an inspection object in the plan view of the inspection object mounted on a tray and covered by a transparent packaging film, has the length equal to or greater than the length of the closest side of the outermost contour of the inspection object and emits light source light. The diffuser plate is installed on the outer side with respect to the outermost contour of the inspection object, has the length equal to or greater than the closest side of the outermost contour of the inspection object and diffuses the light source light from the light source. The camera images reflection light from the inspection object of planarly uniform light irradiated on the inspection object via the diffuser plate from the light source.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present disclosure relates to an imaging device. [Background technology]

[0002] Harvested vegetables or fruits (fruit vegetables) are placed on trays, for example, and then wrapped in packaging film or the like, packed into boxes, and shipped.

[0003] It is desirable for these types of products to be subjected to various inspections to check for defects before being packed in boxes, and an imaging device may be used for these inspections. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3886006 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable to inspect products such as fruits and vegetables immediately before shipping, i.e., while they are placed on a tray and covered with a transparent packaging film. Typically, this type of inspection is performed by irradiating light from a light source in a dark box to eliminate the influence of external light, while collecting images of the fruits and vegetables placed on the tray with a camera. However, the reflectivity of the packaging film that wraps the fruits and vegetables is generally higher than that of the fruits and vegetables themselves. Furthermore, packaging films are much smoother than the fruits and vegetables themselves, and also have a higher refractive index. Furthermore, because fruits and vegetables placed on trays are natural objects, their shapes vary. Therefore, the shape of the packaging film covering the fruits and vegetables can also vary depending on the shape of the fruits and vegetables. Packaging films with such various shapes naturally reflect light from the light source at various angles. This can result in variations in the amount of reflected light entering the camera, or in the reflected light entering the camera from a specific angle having a large amount of light, making image inspection difficult.

[0006] The present disclosure aims to provide an imaging device that can properly capture an image of an item covered with a packaging film. [Means for solving the problem]

[0007] An imaging device according to one aspect includes a light source, a diffuser, and a camera. The light source is installed outside the outermost contour of the inspection object when the inspection object is placed on a tray and covered with a transparent packaging film in a plan view, has a length equal to or greater than the length of the closest side of the inspection object's outermost contour, and irradiates light source light. The diffuser is installed outside the outermost contour of the inspection object, has a length equal to or greater than the length of the closest side of the inspection object's outermost contour, and diffuses the light source light from the light source. The camera captures light reflected from the inspection object from the surface-uniform light irradiated onto the inspection object from the light source via the diffuser. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an imaging device that can properly capture an image of an item covered with a packaging film. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a boxing system for items including an imaging device according to an embodiment. [Figure 2A] FIG. 2A is a diagram schematically illustrating a first configuration example of an imaging device. [Figure 2B] FIG. 2B is a diagram schematically illustrating a first configuration example of an imaging device. [Figure 2C] FIG. 2C is a diagram showing the relationship between the transport direction and the absorption axis when the polarizer is an absorptive polarizer. [Figure 3A] FIG. 3A is a diagram schematically illustrating a second configuration example of the imaging device. [Figure 3B] FIG. 3B is a diagram schematically illustrating a second configuration example of the imaging device. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of a control system for a boxing system for products. [Figure 5] FIG. 5 is a diagram illustrating an example of the operation of the imaging device. [Figure 6] FIG. 6 is a flowchart showing the operation of adjusting the polarization direction. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating an example of a configuration of a boxing system for items including an imaging device according to an embodiment. In FIG. 1, three mutually orthogonal directions are defined: an x-direction, a y-direction, and a z-direction. The boxing system for items packs items into packaging boxes B1-B4. In the embodiment, a package is assumed as the item. The package in the embodiment is an article formed by placing food such as fruit or vegetables, for example, myoga (Japanese ginger), on a tray, wrapping the tray with the food in a transparent packaging film, and further attaching a label to the packaging film. Here, the transparent packaging film in the embodiment may be made of at least one of polyolefin (polyethylene, polypropylene), polyvinyl chloride, polyester, cellulose, etc. Placing the myoga on the tray, wrapping the tray in a packaging film, and attaching a label to the packaging film may be performed automatically or manually in a system further upstream of the boxing system according to the embodiment.

[0011] The boxing system for products includes a belt conveyor 10, a conveyance speed detector 20, an imaging device 30, a first robot R1, and a second robot R2.

[0012] The belt conveyor 10 comprises a conveyor belt and a pair of rotating supports. The conveyor belt is a loop-shaped belt for conveying items in a conveying direction, which is, for example, the x direction in FIG. 1. The rotating supports are disposed at each of the upstream and downstream ends of the belt conveyor 10. The pair of rotating supports are columnar or cylindrical supports inscribed in the conveyor belt. The rotation axis of the rotating supports is approximately parallel to the y direction in FIG. 1, which is the width direction of the conveyor belt. When the rotating supports rotate at the upstream and downstream ends, the cylindrical surfaces of the rotating supports in contact with the conveyor belt feed the conveyor belt in the conveying direction.

[0013] As will be explained later, the imaging device 30 identifies the tray based on the contrast between the tray and the conveyor belt in the image. Therefore, it is desirable that the conveyor belt have a high contrast with the tray. Generally, black is the preferred color for trays of food such as fruits and vegetables. In this case, it is desirable that the color of the conveyor belt be close to white. If the tray is colored, it is desirable that the color of the conveyor belt be a color that is complementary to the color of the tray.

[0014] The conveying speed detector 20 is a detector that detects the conveying speed of the conveying belt. The conveying speed is detected, for example, from the distance that the conveying belt is sent out in the conveying direction per unit time. This distance is detected, for example, by an encoder. The conveying speed detector 20 transmits the detected value to a first controller CTR1, which will be described later.

[0015] The imaging device 30 is installed near the upstream end of the belt conveyor 10. The imaging device 30 captures images of items fed onto the conveyor belt of the belt conveyor 10 from above the conveyor belt. The imaging device 30 can also detect the edge of the tray of items from the captured image and determine whether the packaging film has peeled off. If a label is attached to the packaging film, the imaging device 30 can detect the position of the label from the captured image and determine whether the label shape is abnormal and whether the label position is correct based on preset information about the label. The imaging device 30 can also detect the position and orientation of the conveyed item on the conveyor belt from the captured image. Details of the imaging device 30 will be described later.

[0016] The first robot R1 and the second robot R2 may have the same configuration. Each of the first robot R1 and the second robot R2 includes a base 40, a first arm A1, a second arm A2, a first axis AX1, a second axis AX2, a third axis AX3, a fourth axis AX4, and a hand adjustment unit 50.

[0017] The base 40 is a base for fixing the first robot R1 and the second robot R2.

[0018] A first axis AX1 is disposed on the base 40. The first axis AX1 is supported by the base 40 so as to be rotatable around a rotation axis extending in the z direction. The first axis AX1 is connected to one end of a first arm A1. The first arm A1 is a robot link that connects the first axis AX1 and the second axis AX2. The first arm A1 extends substantially parallel to the xy plane. The position of the first arm A1 is controlled by the rotation angle of the first axis AX1.

[0019] A second axis AX2 is connected to the other end of the first arm A1. The second axis AX2 is supported by the first arm A1 so as to be rotatable around a rotation axis extending in the z direction. The second axis AX2 is connected to one end of the second arm A2. The second arm A2 is a robot link that connects the second axis AX2 and the third axis AX3, and between the second axis AX2 and the fourth axis AX4. The second arm A2 is disposed to extend substantially parallel to the xy plane. The position of the second arm A2 is controlled by the rotation angles of the first axis AX1 and the second axis AX2.

[0020] A third axis AX3 and a fourth axis AX4 are connected to the other end of the second arm A2. The third axis AX3 has a cylindrical axis extending, for example, in a direction substantially parallel to the xy plane, and moves the shaft SFT held at the other end of the second arm A2 in the z direction by coming into contact with the shaft SFT. The fourth axis AX4 has a cylindrical axis extending in the z direction, for example, and rotates the shaft SFT around a rotation axis extending in the z direction by coming into contact with the shaft SFT held at the other end of the second arm A2.

[0021] The hand adjustment unit 50 comprises a shaft SFT that is movable in the z direction by a third axis AX3 and rotatable around a rotation axis extending in the z direction by a fourth axis AX4, and a hand unit HND fixed to one end of the shaft SFT.

[0022] The first arm A1, the second arm A2, and the hand adjustment unit 50 adjust the positions and rotation angles of the first axis AX1, the second axis AX2, the third axis, the fourth axis AX4, and the shaft SFT to control the three-dimensional position of the hand unit HND and its inclination relative to the conveying direction. The hand unit HND has a suction unit. The hand unit HND holds the item by suctioning it with the suction unit. The hand unit HND then releases suction at the position of the packing box B1-B4, thereby packing the item into the packing box B1-B4.

[0023] Next, the imaging device 30 will be described. Figures 2A and 2B are diagrams schematically showing a first configuration example of the imaging device 30. Here, Figure 2A is a diagram of the imaging device 30 of the first configuration example as seen from above, which is the positive side in the z direction, and Figure 2B is a cross-sectional view of the imaging device 30 of the first configuration example as seen from the right side, which is the negative side in the y direction. The imaging device 30 includes a light-shielding housing 301, a light source 302, a diffuser 303, a camera 304, a vision system VS, and a polarizer 305. The vision system VS will be described later.

[0024] The light-shielding housing 301 is disposed as close to the conveyor belt 10 as possible without interfering with the conveyance of the article by the belt conveyor 10 in order to prevent external light from entering the article as the inspection target O of the imaging device 30. The light-shielding housing 301 is made of a light-shielding material and houses a light source 302, a diffuser 303, a camera 304, a vision system VS, and a polarizer 305 therein. The light-shielding housing 301 is formed by stacking two boxes of different sizes in the z direction. The lower box houses the light source 302 and the diffuser 303. The upper box houses the camera 304, the vision system VS, and the polarizer 305. A hole is formed in the ceiling of the lower box, and the camera 304 and the polarizer 305 are disposed therein so that the camera 304 can receive light entering through the hole. In this embodiment, the inner wall of at least the lower box of the light-shielding housing 301 is white. Since the inner wall of the light-shielding housing 301 is white, light from the light source is more likely to be scattered and reflected by the inner wall of the light-shielding housing 301. This is expected to improve the amount of light irradiated onto the inspection object O. Here, the description of the configuration of the light-shielding housing 301, including the color of the inner wall, shows only a preferred example, and is not necessarily limited to this.

[0025] In the embodiment, the light-shielding housing 301 is configured with two boxes to house the camera 304, the vision system VS, and the polarizer 305. However, for example, if the vision system VS is built into the camera 304 or if the vision system VS is provided separately from the image capturing device 30, the upper box may be omitted.

[0026] The shape of the light-shielding casing 301 may also be determined according to the shape of the inspection object O. For example, if the inspection object O is an item including a food tray, the outer shape when viewed in a plane is approximately rectangular. Therefore, the light-shielding casing 301 is also formed into a box shape with an approximately rectangular outer shape when viewed in a plane. However, depending on the shape of the inspection object O, the outer shape of the light-shielding casing 301 when viewed in a plane may be a shape other than rectangular.

[0027] The light source 302 is installed at a position where it does not interfere with the transport of an item serving as the inspection object O and where it can uniformly irradiate the inspection object O with light, more specifically, at a position outside the outermost contour of the inspection object O when viewed in a planar direction. The outermost contour is the outermost contour of the inspection object O when viewed in a planar direction. For example, in a first configuration example, as shown in FIG. 2A , the light source 302 is a line light source installed on each of two wall surfaces of the light-shielding housing 301 parallel to the x-direction, which is the transport direction, so as to extend along the x-direction, which is the transport direction. Meanwhile, the installation height of the light source 302 may be any position as long as it does not interfere with the transport of the item, and may be, for example, a position near the center of the wall surface of the light-shielding housing 301, as shown in FIG. 2B .

[0028] The light emission color, i.e., the light emission wavelength, of light source 302 can be appropriately selected to match the hue of the item serving as inspection object O. For example, if inspection object O is an item including a food tray, a white light source can be used as light source 302 because of its ease of availability, the uniform reflection wavelength of the packaging film, and the fact that black is a popular color for trays. The white light source can be appropriately selected from incandescent lamps, cold cathode fluorescent lamps, light-emitting diodes (LEDs), etc., depending on installation method constraints, power consumption constraints, etc. However, since the inspection object O is assumed to be food in this embodiment, it is more preferable to select a white LED, which generates less heat, as the white light source. In this case, light source 302 can be configured by arranging multiple white LEDs in the x direction.

[0029] Here, the light source 302 in the embodiment has a length sufficient for the length of the closest side of the outline of the inspection object O. Specifically, in the first configuration example, the length of the light source 302 along the x direction is sufficiently longer than the length in the x direction of a tray having a substantially rectangular shape as the outline of the inspection object O.

[0030] The diffusion plate 303 is installed at a position where it can diffuse the light source light emitted from the light source 302, more specifically, at a position outside the outermost contour of the inspection object O when viewed in the planar direction and at a position where the light source light from the light source 302 is incident. For example, in a first configuration example, the diffusion plate 303 is arranged parallel to the light source 302, for example, at the light emission portion of the light source 302, as shown in Fig. 2A. This diffusion plate 303 is arranged to convert the light source light into uniform light.

[0031] The diffusion plate 303 needs to be able to sufficiently diffuse the light source light from the light source 302. For this reason, the diffusion plate 303 can be appropriately selected depending on the combination with the light source 302, but it is desirable that the diffusion plate 303 has a high degree of scattering.

[0032] Furthermore, the diffuser 303 in the embodiment also has a length sufficient relative to the length of the closest side of the contour of the inspection object O. Specifically, in the first configuration example, the length of the diffuser 303 in the x direction is sufficiently longer than the length of the tray as the inspection object O in the x direction. More preferably, as shown in FIGS. 2A and 2B , the length of the diffuser 303 in the x direction is sufficiently longer than the length of the light source 302 in the x direction. This allows the light source light from the light source 302 to be incident on the diffuser 303 without leakage.

[0033] The camera 304 includes a lens and an image sensor. The lens of the camera 304 is disposed in a hole in the upper surface of the lower box of the light-shielding housing 301, and forms an image on the image sensor of light irradiated from the inspection object O via the diffuser 303 and reflected from the object. The image sensor generates image data by converting the light received via the lens into an electrical signal. The image sensor then outputs the generated image data to the vision system VS. The image sensor in the embodiment may be an image sensor having a resolution, i.e., a number of pixels, sufficient to identify the tray on the image. The image sensor may also be an image sensor equipped with a color filter to generate a color image, or an image sensor without a color filter to generate a monochrome image.

[0034] The polarizer 305 is placed on the optical path of the lens of the camera 304. For example, in Fig. 2A, the polarizer 305 is placed just before the lens of the camera 304. The polarizer 305 may be configured to be attached to the lens of the camera 304. Various polarizers such as a polarizing film can be used as the polarizer 305.

[0035] Here, the polarization direction of the polarizer 305 is adjusted so as to reduce incidence of specularly reflected light from the packaging film on the camera 304. The applicant's studies have confirmed that when the inspection target O includes a long item and the inspection target O is transported with its length oriented in the x-direction parallel to the transport direction, incidence of specularly reflected light from the packaging film on the camera 304 is reduced by setting the polarization direction of the polarizer 305 parallel to the transport direction. In other words, for long items, the influence of reflected light from the length of the item is significant. Therefore, it is desirable to set the polarization direction of the polarizer 305 in a direction that reduces incidence of reflected light from the length of the item, i.e., parallel to the length of the item. Note that when long items are placed on a rectangular tray, the items are typically placed with the long sides of the rectangular tray aligned in the long direction, and are often transported with the long sides of the rectangular tray aligned in the x-direction parallel to the transport direction. In this case, the polarization direction of the polarizer 305 can also be said to be the x-direction parallel to the transport direction.

[0036] Fig. 2C is a diagram showing the relationship between the longitudinal direction and absorption axis of an article when the polarizer 305 is an absorptive polarizer. As shown in Fig. 2C, when the article is transported so that its longitudinal direction is the x-direction, the polarizer 305 is adjusted so that its absorption axis A is in the x-direction. Note that Fig. 2C also shows the transmission axis T of the polarizer 305. Since the absorption axis A is in the x-direction, the direction of the transmission axis T is in the y-direction.

[0037] The polarizer 305 may be a reflective polarizer, in which case the polarizer 305 is adjusted so that the reflective axis of the polarizer 305 is in the x direction when the article is transported with its long dimension in the x direction.

[0038] The imaging device 30 described above irradiates the inspection object O with uniform light. When trays containing food such as fruits and vegetables and wrapped in packaging film are identified by image recognition, light reflected from the packaging film adversely affects the recognition process. This reflected light occurs when light from a limited-range light source, such as a point light source or a linear light source, is reflected at a specific angle by the surface of the packaging film, which deforms according to the shape of the fruit and vegetables. In the embodiment, the light source light is converted into uniform light by the diffuser 303, thereby reducing the incidence of light from the source light only from a specific angle. This reduces variation in the amount of light reflected to the camera 304. Furthermore, in the embodiment, because the light source light is converted into uniform light by the diffuser 303, the light source 302 is not reflected by the packaging film, even if a linear light source is used as the light source 302.

[0039] Furthermore, packaging film has a higher reflectivity than fruit and vegetables. Therefore, light from a light source that is normally incident on the packaging film may enter the camera 304 as a large amount of reflected light. In contrast, in the embodiment, the polarization direction of the polarizer 305 is adjusted to reduce the large amount of reflected light from the packaging film that enters the camera 304. In fact, the polarizer 305 may also absorb light reflected from food placed on a tray. However, because the reflectivity of the packaging film is generally higher than that of the food, the amount of light reflected from the packaging film is greater than the amount of light reflected from the food. Therefore, the amount of light reflected by the packaging film by the polarizer 305 is greater than the amount of light reflected from the food. Therefore, while much of the light reflected from the packaging film is absorbed by the polarizer 305, the light reflected from the food is hardly affected by the polarizer 305.

[0040] In this way, the imaging device of the embodiment can appropriately capture an image of an item that has food such as fruit or vegetables loaded thereon and is wrapped in a wrapping film.

[0041] 3A and 3B are diagrams schematically illustrating a second configuration example of the imaging device 30. Here, FIG. 3A is a diagram of the imaging device 30 of the second configuration example as viewed from above, which is the positive side in the z direction, and FIG. 3B is a cross-sectional view of the imaging device 30 of the second configuration example as viewed from the right side, which is the positive side in the y direction. Here, in the second configuration example, descriptions of components similar to those in the first configuration example will be omitted or simplified. Specifically, descriptions of components other than the light source 302 and the diffuser 303 will be omitted.

[0042] In the second configuration example, the light source 302 is a line light source installed on each of two wall surfaces of the light-shielding housing 301 that are orthogonal to the x direction, which is the conveying direction, so as to extend along the y direction, which is the direction orthogonal to the conveying direction, as shown in Fig. 3A. Meanwhile, the installation height of the light source 302 may be any position as long as it does not interfere with the conveyance of the article, and may be, for example, a position near the center of the wall surface of the light-shielding housing 301, as shown in Fig. 3B.

[0043] In the second configuration example, the length of the light source 302 in the y direction is sufficiently longer than the length of the tray as the inspection object O in the y direction.

[0044] 3A, in the second configuration example, the diffuser plate 303 is arranged parallel to the light source 302, i.e., in a direction perpendicular to the arrangement direction in the first configuration example. In the second configuration example, the length of the diffuser plate 303 in the y direction is sufficiently longer than the length of the tray as the inspection object O in the y direction. More preferably, as shown in FIG. 3A, the length of the diffuser plate 303 in the y direction is sufficiently longer than the length of the light source 302 in the y direction. This allows the light source light from the light source 302 to be incident on the diffuser plate 303 without leakage.

[0045] The second configuration example is also expected to have the same effect as the first configuration example. Furthermore, the first and second configuration examples may be used in combination. That is, the light source 302 may be installed on each of the four wall surfaces of the light-shielding housing 301 parallel to and perpendicular to the x direction, which is the transport direction, and the diffusion plate 303 may be installed parallel to each light source 302.

[0046] 4 is a block diagram showing an example of the configuration of a control system of a boxing system for products according to this embodiment. The boxing system for products according to this embodiment includes a first controller CTR1, a second controller CTR2, a vision system VS, and a network hub HUB.

[0047] The first controller CTR1 is a master controller that performs various calculations to control the first robot R1 and the second robot R2 using information on the conveying speed obtained from the conveying speed detector 20 and information obtained from the vision system VS of the imaging device 30. The first controller CTR1 includes at least one processor, such as a CPU (central processing unit) or an MPU (micro processing unit), and a memory in which programs executed by the processor are recorded.

[0048] The second controller CTR2 is a slave controller that controls the second robot R2 according to information obtained from the first controller CTR1. The second controller CTR2 includes at least one processor, such as a CPU or an MPU, and a memory that stores a program to be executed by the processor.

[0049] The vision system VS uses image data obtained by the camera 304 to detect the edges and label shapes of the items, and calculates the position and inclination of the items on the belt conveyor 10. The vision system VS includes at least one processor, such as a CPU or MPU, and a memory that stores programs executed by the processor.

[0050] The network hub HUB is connected to the first controller CTR1, the second controller CTR2, and the vision system VS via a network cable such as an Ethernet (registered trademark) cable. The first controller CTR1, the second controller CTR2, and the vision system VS can communicate with each other via the network hub HUB.

[0051] The control block of the product packing system of this embodiment is not limited to the configuration shown in Fig. 4. For example, the first controller CTR1, the second controller CTR2, and the vision system VS may be connected to each other so that they can communicate without going through a network hub HUB. If the first controller CTR1, the second controller CTR2, and the vision system VS can communicate wirelessly, the network cable may be omitted.

[0052] Furthermore, the first controller CTR1 and the second controller CTR2 do not necessarily have a master-slave relationship, but may have an equivalent relationship. For example, the product packing system may be configured to include a system controller that coordinates and controls the entire system, and the system controller may be configured to control the operations of the first controller CTR1, the second controller CTR2, and the vision system VS.

[0053] Next, an example of the operation of the imaging device according to the embodiment will be described. Fig. 5 is a diagram for explaining an example of the operation of the imaging device. When an item is supplied to the upstream end of the belt conveyor 10, the belt conveyor 10 operates to transport the item in the x direction, which is the transport direction. As the item is transported, the camera 304 of the imaging device 30 captures an image of the item. The frame rate of the camera 304 is synchronized with the transport speed.

[0054] In step S 1 , the vision system VS acquires image data input by the camera 304 .

[0055] In step S2, the vision system VS performs image processing to detect the edge of the product tray and the shape of the label from the image data. As described above, the light source 302 and the diffuser 303 irradiate the product as the inspection target O with uniform light, and the polarizer 305 reduces reflected light from the packaging film that enters the camera 304. Therefore, the vision system VS can perform image processing without being affected by the packaging film.

[0056] In step S3, the vision system VS extracts an image of the tray portion from the detected tray edge and compares the extracted image of the tray portion with a pre-stored image of a reference tray portion to determine whether the packaging film has peeled off. If it is determined in step S3 that the packaging film has peeled off, the vision system VS does not select the currently processed item as a defective product for boxing. In this case, the vision system VS proceeds to step S7 without transferring data to the first controller CTR1. If the data has not been transferred, the first controller CTR1 and the second controller CTR2 wait for the processing. Alternatively, if the data has not been transferred, the first controller CTR1 and the second controller CTR2 cause the first robot R1 and the second robot R2 to wait. If it is determined in step S3 that the packaging film has not peeled off, the vision system VS proceeds to step S4.

[0057] In step S4, the vision system VS detects a label from the image of the tray portion and determines whether there is an abnormality in the label based on the shape of the detected label. For example, the vision system VS determines whether the shape of the detected label is a predetermined shape and whether the position where the label is affixed is a predetermined position. The vision system VS determines that there is an abnormality in the label when the shape of the label is not a predetermined shape or when the position where the label is affixed is not a predetermined position. If it is determined that there is an abnormality in the label in step S4, the vision system VS does not transfer data to the first controller CTR1 and proceeds to step S7. If it is determined that there is no abnormality in the label in step S4, the vision system VS proceeds to step S5.

[0058] In step S5, the vision system VS detects the position and inclination of the item on the conveyor belt from the inclination of the edge of the tray in the image.

[0059] In step S6, the vision system VS transfers the detected item position and tilt data to the first controller CTR1. The vision system VS then transitions the process to step S7. The first controller CTR1 controls the first arm A1, the second arm A2, and the hand adjustment unit 50 based on the item position and tilt data, and packs the item into a box using the hand unit HND. The first controller CTR1 also transfers the item position and tilt data to the second controller CTR2 as needed. The second controller CTR2 controls the first arm A1, the second arm A2, and the hand adjustment unit 50 based on the item position and tilt data, and packs the item into a box using the hand unit HND.

[0060] In step S7, the vision system VS determines whether to end the process. If the vision system VS determines that the packing system is operating, for example, due to an operation continuation command supplied from the first controller CTR1, it determines not to end the process. In this case, the vision system VS returns the process to step S1. If the vision system VS determines in step S7 that the packing system is not operating, for example, due to an operation interruption command supplied from the first controller CTR1, it determines to end the process. In this case, the vision system VS ends the process of FIG. 5.

[0061] As described above, according to the embodiment, images of items such as fruits and vegetables placed on a tray and covered with a packaging film can be captured appropriately, thereby enabling proper inspection of the items using images and accurate grasping, suction, and boxing of the items placed on the tray.

[0062] Furthermore, the imaging device of the embodiment can reduce the influence of reflected light from the packaging film by using a light source that emits uniform light and a polarizer placed in the camera lens. Because the imaging device of the embodiment has a simple structure, it can be installed in a small space. Furthermore, maintenance of the imaging device can be easily performed.

[0063] [Variations] Modifications of the embodiment will be described below. In the embodiment, the light source is disposed on the side of the light-shielding housing. Alternatively, the light source may be disposed on the upper surface of the light-shielding housing by a coaxial epi-illumination structure using, for example, a half mirror. As such, the configuration of the light source in the embodiment is not limited to a specific configuration as long as it can irradiate uniform light over an area wider than the outermost contour of the object to be inspected.

[0064] In the embodiment, the polarization direction of the polarizer 305 is adjusted according to the longitudinal direction of the product. This adjustment is based on the results of the applicant's studies. The polarizer 305 may be configured so that such adjustment of the polarization direction can be performed sequentially before the product is packed into a box. For example, when the polarizer 305 is placed on the lens of the camera 304, the polarizer 305 may be configured so that the polarization direction can be adjusted by rotating the polarizer 305 around the optical axis of the lens under the control of the vision system VS.

[0065] Fig. 6 is a flowchart showing the operation of adjusting the polarization direction. The operation of Fig. 6 is performed before the operation of Fig. 5. The operation of Fig. 6 may be performed after each operation of Fig. 5, or may be performed only before the first operation of Fig. 5.

[0066] During the operation of adjusting the polarization direction, the item for adjusting the polarization direction placed on the conveyor belt is imaged by the imaging device 30. The item for adjusting the polarization direction may be an article formed by placing food such as fruit or vegetables, for example, myoga ginger, on a tray, wrapping the tray with the fruit or vegetables in a wrapping film, and further attaching a label to the wrapping film, just like a normal item.

[0067] In step S11, the vision system VS acquires image data input by the camera 304.

[0068] In step S12, the vision system VS determines whether the flare in the image is small based on the image data. For example, the vision system VS determines that the flare in the image is small when the number of pixels with saturated brightness in the image is equal to or less than a threshold. If the vision system VS determines that the flare is not small in step S12, this means that the polarizer 305 has not been properly adjusted and that the influence of reflected light from the packaging film is large. In this case, the vision system VS proceeds to step S13. On the other hand, if the vision system VS determines that the flare is small in step S12, this means that the polarizer 305 has been properly adjusted. In this case, the vision system VS ends the process of FIG. 6. Note that the determination in step S12 may be made visually by a human. In this case, the vision system VS displays the image obtained by the camera 304 on a display device. A human can determine whether the flare is small by looking at this image.

[0069] In step S13, the vision system VS rotates the polarizer 305 by a predetermined small angle. After that, the vision system VS returns the process to step S11. Note that the polarization direction of the polarizer 305 may be adjusted manually.

[0070] The above-described modified examples allow the polarization direction of the polarizer to be adjusted more appropriately. By adjusting the polarization direction of the polarizer appropriately, the amount of reflected light from the packaging film can be reduced more reliably.

[0071] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0072] 10 conveyor belt, 20 conveyance speed detector, 30 imaging device, 40 base, 50 hand adjustment unit, 301 light-shielding housing, 302 light source, 303 diffuser plate, 304 camera, 305 polarizer.

Claims

1. A light source that is placed outside the outermost contour of an object to be inspected when the object is mounted on a tray and covered with a transparent packaging film and viewed in plan, has a length equal to or greater than the length of the closest side of the outermost contour of the object to be inspected, and irradiates light from the light source; a diffusion plate that is placed outside the outermost contour of the object to be inspected, has a length equal to or greater than the length of the closest side of the outermost contour of the object to be inspected, and diffuses the light source light from the light source; a camera that captures an image of light reflected from the inspection object from surface uniform light irradiated onto the inspection object from the light source via the diffusion plate; An imaging device comprising:

2. The imaging device according to claim 1 , wherein the length of the diffusion plate is longer than the length of the light source.

3. 3. The imaging device according to claim 1, further comprising a polarizer that polarizes the reflected light that enters the camera.

4. The object to be inspected includes a long item, 4. The imaging device according to claim 3, wherein the polarization direction of the polarizer is set parallel to the longitudinal direction of the article.

5. 4. The imaging device according to claim 3, wherein the polarization direction of the polarizer is adjustable.

6. the light source and the diffusion plate are disposed in a light-shielding housing; 6. The imaging device according to claim 1, wherein the camera is disposed in a hole formed in the light-shielding housing.

7. The imaging device according to claim 6 , wherein the inner wall of the light-shielding housing is white.

8. The imaging device according to claim 1 , wherein the tray is black or white.

9. The imaging device according to claim 1 , wherein the light source emits white light.

Images