Article image-capturing device, inspection device, and article image-capturing method

Abstract

To provide an article image-capturing device, inspection device, and article image-capturing method that boost the number of photographing images, while ensuring a required image resolution in a configuration of combining a plurality of images obtained by image-capturing an article from a different direction.SOLUTION: An article image-capturing device 11 comprises: N pieces of cameras 25 (where, N is a natural number satisfying 2≤N<M); a detection unit 30; an image-capturing control unit 51; and an image composite unit 53. N pieces of cameras 25 are configured to share image capturing for image-capturing a work W M times (where, M is a natural number more than 3) from a different direction relative to circumference direction. The image-capturing control unit 51 is configured to generate image-capturing trigger signals Trg1 to TrgN including M pieces of trigger pulses based on a detection pulse on the basis of a detection result of the detection unit 30. The image-capturing control unit 51 is configured to cause M pieces of cameras 25 to image-capture the work W Ki times (i=1, ..., N) on the basis of M pieces of trigger pulses. The image composite unit 53 is configured to combine an area TA of a work WI out of M pieces of images FI, and generate a composite image CI.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an article imaging device, an inspection device, and an article imaging method that synthesize and output a plurality of images obtained by imaging an article from different directions. [Background technology]

[0002] For example, Patent Documents 1 to 3 disclose imaging devices that capture a full-circle image or a developed image of an object based on a plurality of captured images captured by a camera of an object moving along a moving path while rotating on its axis. For example, Patent Document 1 includes a sensor that detects that the object has reached a predetermined position within the field of view of the camera. When the sensor detects the object, this is used as an image capture trigger to capture images of the object at predetermined intervals. The fixed intervals of image capture after the first image is captured are based on the premise that the object rolls without slipping during transport, and a trigger for capturing the second and subsequent images is output each time the transport means travels a predetermined distance based on the output of an encoder attached to the motor of the transport device.

[0003] In Patent Documents 1 to 3, it is assumed that an article moving at a constant speed rotates (spins) at a constant peripheral speed without the influence of friction, etc., and images are taken with a camera using a strobe light, at constant intervals, or at constant moving distances or rotation angles based on a detection signal from an encoder of the motor of the conveying means. Note that in Patent Document 3, if the amount of movement between two images obtained by comparing two consecutive images over time is equal to or exceeds a threshold value, a correction is made to increase the cutting width of the later of the two images when cutting out width portions of multiple images and synthesizing the side image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-350358 A [Patent Document 2] JP 2007-212283 A [Patent Document 3] JP 2016-142592 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when an object rotates at high speed, the image capture interval becomes shorter. In this case, the imaging range of the camera can be made relatively narrow, so that a normal camera (general-purpose camera) can ensure the necessary resolution. However, the imaging cycle of the camera becomes shorter, so it becomes difficult to use a normal camera.

[0006] On the other hand, if the rotation speed of the object is slowed down so that the camera's imaging cycle can be handled by a normal camera, the distance the object moves during one rotation will be long. In this case, it is necessary to ensure a wide imaging range for the camera. Therefore, it is necessary to increase the imaging distance between the camera and the object, which reduces the resolution of the captured image. In order to obtain an image with the required resolution, it is necessary to use an expensive special camera with high resolution. Even if a special camera is used, there is a limit when even higher speeds are required. Therefore, there is a demand for an object imaging device that can handle high-speed conveyance.

[0007] Even in the case of a configuration in which an object is not transported but is rotated at a predetermined imaging position while being imaged by a camera, a normal camera has limitations when rotating at high speed, and a special camera capable of high-speed imaging is required. Furthermore, an object imaging device that obtains a composite image by imaging an object multiple times while moving the camera in a circumferential direction relative to the object also has roughly the same problem. That is, the above problem is also present in an object imaging device that obtains a composite image by combining multiple images obtained by imaging an object multiple times from different directions while moving the camera and the object relative to each other. [Means for solving the problem]

[0008] The means for solving the above problems and their effects will be described below. The article imaging device for solving the above problems acquires M images of different parts in the circumferential direction of the article by imaging the article M times (where M is a natural number of 3 or more) from relatively different directions in the circumferential direction, and N cameras (where N is a natural number satisfying 2 ≤ N < M) that share the M times of imaging for the article, a detection unit that detects the article at a detection position before reaching the imaging position of the first time among the M times, and an imaging trigger signal including M trigger pulses that determine the total M imaging timings for the N cameras to image based on the detection pulses based on the detection results of the detection unit. At the same time, an imaging control unit that causes each of the N cameras to image the article Ki times (i = 1,..., N) (where Ki is a natural number satisfying 1 ≤ Ki < M and the sum of the N Ki values = M) that each shares, and an image synthesis unit that synthesizes into one an article region image including at least a part of the article among the total M images obtained by performing the Ki times of imaging shared by the N cameras to generate a synthesized image.

[0009] According to this configuration, since the M images obtained by imaging the article from different directions in the circumferential direction with the cameras are obtained by imaging the article in a shared manner with a plurality (N) of cameras, the required image resolution is ensured, and while coping with the reduction in the relative rotation speed between the article and the camera, even in a camera with a long imaging cycle, the number of imaging times for imaging different positions of the article can be increased. For example, it can be imaged with an imaging cycle that can be supported by a general-purpose camera, and the required image resolution can be ensured. When using a special camera capable of high-speed imaging, while ensuring the required image resolution, the number of imaging times for imaging different positions of the article can be further increased by shortening the imaging cycle of the camera.

[0010] In the above article imaging device, the N cameras may be fixed at positions where the article can be imaged, and image the article M times while moving along a moving path while rotating. According to this configuration, since the camera captures an image of an article moving along a moving path while rotating on its axis, a complicated mechanism such as a camera rotation mechanism is not required compared to a configuration in which the camera captures an image of an article while moving around the article. Therefore, the article imaging device can be realized with a simple configuration.

[0011] In the above-mentioned item imaging device, the N cameras may be arranged at intervals along the movement path, and M imaging positions set at imaging intervals from position 1 to position M may be equally divided into N groups of Ki (i = 1, ..., N) cameras each taking an image of the item.

[0012] According to this configuration, multiple (N) cameras equally share the M imaging times, Ki times each (the number of imaging positions is Ki), so image processing can be performed similarly between cameras, and individual processing is not required. Also, the maximum distance among the N cameras can be relatively small in the imaging distance required to fit Ki imaging positions within the imaging area of ​​the camera. Therefore, it becomes easier to obtain the required image resolution in all of the N cameras.

[0013] In the above-mentioned article imaging device, the imaging control unit may generate N imaging trigger signals each including the Ki number of M trigger pulses at a timing when M parts located at equal intervals in the circumferential direction of the article can be imaged from the front, and may output the N imaging trigger signals to the N cameras. Note that the front may be the front when the article is viewed from the camera side in a direction parallel to the optical axis of the camera, or the front may be the direction in which the article faces the camera.

[0014] According to this configuration, a composite image such as a panoramic image suitable for inspection, etc. can be obtained. In the above-mentioned item imaging device, the N cameras are numbered i (i = 1, ..., N) in order from the earliest camera to capture the same item for the first time, and the imaging control unit may generate M trigger pulses at a timing when the imaging period required for the i-th camera to capture Ki images partially overlaps with the imaging period required for the adjacent camera in the order to capture Ki images.

[0015] According to this configuration, the space required for arranging the N cameras around the movement path can be reduced in the direction along the movement path, making it possible to reduce the size of the article imaging device. In the above-mentioned product imaging device, the N cameras are arranged in a zigzag pattern alternately positioned at a predetermined distance on both sides of the movement path, and the imaging control unit may generate Ki trigger pulses to be output to the next camera in the sequence for the i-th camera, at a timing that is phase-shifted by an adjustment time that is set to a value smaller than the imaging period in order to adjust the timing due to both cameras capturing images from opposite sides of the movement path.

[0016] According to this configuration, since the N cameras are arranged in a zigzag pattern, the imaging periods of the cameras can be partially overlapped, and the imaging timing can be aligned among the N cameras. For example, even with a general-purpose camera, the number of images taken at different positions of an article can be increased while ensuring the required image resolution.

[0017] In the above-mentioned item imaging device, the movement path has N movement path segments that move the item along a straight or curved path so as to pass through Ki imaging positions where each of the N cameras captures an image, and each of the N cameras is arranged in a direction such that its optical axis intersects with a virtual line connecting the first imaging position and the Ki imaging position at an angle within an allowable range of ±10° from a right angle, and the angle formed by the optical axes of the N cameras may be set to an angle corresponding to 360° / M.

[0018] According to this configuration, since the imaging periods can be partially overlapped among N cameras, the size of the article imaging apparatus can be reduced. The inspection apparatus for solving the above problems includes the article imaging apparatus and an inspection processing unit that inspects the article based on the composite image input from the article imaging apparatus.

[0019] According to this configuration, since the inspection process is performed using a composite image obtained by synthesizing images with the required image resolution and the required number of images, the required inspection accuracy can be ensured. The article imaging method for solving the above problems includes obtaining M images of different portions in the circumferential direction of the article by imaging the article M times (where M is a natural number of 3 or more) from relatively different directions in the circumferential direction, N cameras (where N is a natural number satisfying 2 ≦ N < M) that share the M - time imaging of the article, and a detection unit that detects the article at a detection position before reaching the imaging position of the first time among the M times and outputs a detection pulse. The article imaging method using the article imaging apparatus includes generating an imaging trigger signal including M trigger pulses for determining the total M - time imaging timings at which the N cameras image based on the detection pulse, the N cameras each performing the imaging of the article Ki times (i = 1,..., N) (where Ki is a natural number satisfying 1 ≦ Ki < M and the sum of the N Ki values = M) that each camera shares based on the M trigger pulses, and generating a composite image by synthesizing into one an article region image including at least a part of the article among the total M images obtained by the N cameras performing the Ki - time imaging that each camera shares.

[0020] According to this method, since the article is imaged a plurality of times from different directions in the circumferential direction by sharing among N cameras, while ensuring the required image resolution, it is also possible to cope with a reduction in the relative rotational speed between the article and the camera, and increase the number of imaging times for imaging different positions of the article. For example, it is possible to image at an imaging cycle that a general - purpose camera can handle and ensure the required image resolution. When using a special camera capable of high - speed imaging, while ensuring the required image resolution, by further shortening the imaging cycle of the camera, the number of imaging times for imaging different positions of the article can be further increased.

Advantages of the Invention

[0021] According to the present invention, in a configuration in which a camera captures an article from multiple different directions and combines multiple images obtained, it is possible to increase the number of images captured of different positions on the article while ensuring the required image resolution. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram showing an inspection device equipped with an article imaging device according to the first embodiment. [Diagram 2] FIG. 2 is a side view showing an article and a camera being transported by the transport device. [Diagram 3] FIG. 3 is a schematic diagram illustrating M imaging positions. [Figure 4] FIG. 4 is a schematic diagram showing an article imaging device. [Diagram 5] FIG. 5 is a timing chart showing the processing of the imaging processing circuit. [Figure 6] FIG. 6 is a schematic diagram illustrating the configuration of a control unit provided in the inspection device and image processing. [Figure 7] FIG. 7 is a schematic diagram showing an article imaging device according to the second embodiment. [Figure 8] FIG. 8 is a timing chart showing the processing of the imaging processing circuit. [Figure 9] FIG. 9 is a schematic diagram showing an article imaging device according to the third embodiment. [Figure 10] FIG. 10 is a timing chart showing the processing of the imaging processing circuit. [Figure 11] FIG. 11 is a schematic diagram showing a part of an article imaging device according to the fourth embodiment. [Figure 12] FIG. 12 is a schematic diagram showing an article imaging device. [Figure 13] FIG. 13 is a timing chart showing the processing of the imaging processing circuit. [Figure 14] FIG. 14 is a schematic diagram showing an imaging processing circuit and the like in the modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (First embodiment) The first embodiment will be described below with reference to FIGS. 1, the inspection device 10 includes an article imaging device 11 that images an article W (workpiece), and an inspection processing unit 60 that inspects the presence or absence of defects in the article W based on an inspection image generated by the article imaging device 11. Note that, although the number N of cameras 25 included in the article imaging device 11 will be described as three as an example, N may be any number equal to or greater than two.

[0024] The article imaging device 11 includes a conveying device 12 that conveys the article W along the moving path MT at a predetermined interval. The conveying device 12 includes a conveying device 13 that conveys the article W to the moving path MT, a conveying section 23 that moves the article along the moving path MT while rotating it, and a conveying device 14 that conveys the article W that has finished moving along the moving path MT by the conveying section 23. The inspection device 10 of this embodiment is incorporated in the middle of a production system. The article imaging device 11 captures an image of a container, which is an example of the produced article W, or a container used in the production of a beverage product, etc., in which a liquid or the like is poured into the container. In this embodiment, the article imaging device 11 is used, as an example, for capturing and generating an inspection image for inspecting the article W, but the article imaging device 11 may be used for purposes other than inspection.

[0025] The carry-in device 13 includes a gap adjustment device 15 that adjusts the gap between the articles W carried into the conveying section 23, and a carry-in conveyor 16 that carries the articles W with the adjusted gap toward the conveying conveyor 17 at a constant carry-in speed. The gap adjustment device 15 employs a known type, such as a screw type, a blade type, or a lever type, and adjusts the gap between the articles W by sending a large number of articles W, which are carried adjacent to each other in a line, one by one onto the carry-in conveyor 16 with a constant time difference. This gap is set to a length that allows the articles W to be carried one by one through the imaging section of the imaging passage 20 where imaging is performed. The gap between the articles W can be adjusted arbitrarily as long as the necessary images can be captured.

[0026] As shown in FIG. 1, the transport section 23 has two belt devices 21 and 22 arranged opposite each other on either side of the imaging passage 20. 1 are disposed symmetrically on both sides of the imaging passage 20. One of the belt devices 21 includes a conveyor belt 31 made of an endless toothed belt wound around a pair of toothed pulleys 28, 28 disposed at a fixed distance in the moving direction MD. The other belt device 22 includes a conveyor belt 32 made of an endless toothed belt wound around a pair of toothed pulleys 29, 29 disposed at positions facing the pair of pulleys 28, 28 on the belt device 21 side with the imaging passage 20 in between.

[0027] The pulleys 28, 29 are arranged so that their axes coincide with the vertical direction (perpendicular to the plane of the paper in FIG. 1), and the pair of conveyor belts 31, 32 are vertical belts whose belt surfaces form vertical planes. The belt surface portions of the pair of conveyor belts 31, 32 that face each other across the imaging passage 20 form conveyor surfaces 31a, 32a that convey the article W while clamping it. The article imaging device 11 is also provided with a shift device 26 that can adjust the interval and height of the two belt devices 21, 22 to adjust the width (passage width) of the imaging passage 20 and the belt height.

[0028] As shown in FIG. 1, the two belt devices 21 and 22 are provided with motors 33 and 34 as their respective drive sources. The belt device 21 is driven by the power of the first motor 33, which is its drive source. The belt device 22 is driven by the power of the second motor 34, which is its drive source. The power of each of the motors 33 and 34 is transmitted to each of the rotation shafts of the drive pulleys 28 and 29 located at the downstream end of each of the belt devices 21 and 22 in FIG. 1 via a power transmission mechanism (not shown). The two motors 33 and 34 can be driven independently at individual rotation speeds. By individually setting the rotation speeds of the two motors 33 and 34, it is possible to set the pair of conveyor belts 31 and 32 to have a speed difference. By providing a speed difference between the pair of conveyor belts 31 and 32, the article W sandwiched between the pair of conveyor surfaces 31a and 32a moves at a constant speed while rotating on its own axis along the moving path MT.

[0029] As shown in FIG. 1, the article imaging device 11 includes rotation detectors E1 and E2 that detect the rotation of the motors 33 and 34. The rotation detectors E1 and E2 are, for example, rotary encoders. The rotation detector E1 outputs a rotation detection signal ES1 including a number of pulses proportional to the rotation speed of the first motor 33. The rotation detector E2 outputs a rotation detection signal ES2 including a number of pulses proportional to the rotation speed of the second motor 34. The control unit 40 performs feedback control to bring the actual rotation speed of the first motor 33 detected based on the rotation detection signal ES1 closer to the target speed. The control unit 40 also performs feedback control to bring the actual rotation speed of the second motor 34 detected based on the rotation detection signal ES2 closer to the target speed. Through these feedback controls, the rotation speed and movement speed of the article W controlled by the control unit 40 are maintained with high accuracy.

[0030] The shift device 26 includes a passage width adjustment mechanism that adjusts the interval between the pair of conveying surfaces 31a, 32a, i.e., the width (passage width) of the imaging passage 20, by changing the relative positions of the two belt devices 21, 22 in the width direction Y (the vertical direction in FIG. 1) perpendicular to the moving direction MD. Here, the width of the imaging passage 20 is adjusted according to the outer diameter of the portion of the article W that is sandwiched between the pair of conveying surfaces 31a, 32a. The shift device 26 also includes a belt height adjustment mechanism that adjusts the height of the belt devices 21, 22 in the vertical direction. The belt height adjustment mechanism can adjust the height position where the pair of conveying surfaces 31a, 32a sandwich the article W. The shift device 26 in this example may be a manual type or an electric type driven by the power of an electric motor (not shown). For example, in the case of an electric type, the conveyor belt interval and belt height may be automatically adjusted based on input values ​​of the outer diameter of the portion where the pair of conveying surfaces 31a, 32a clamp the article W and the belt height.

[0031] 1, the article imaging device 11 is provided with a detection unit 30 capable of detecting an article W near the entrance of the imaging passage 20. The detection unit 30 is disposed at a detection position where the article W can be detected before it reaches an imaging position where imaging starts within an imaging area of ​​a camera 25 described later.

[0032] As shown in FIG. 1, the discharge device 14 provided at the exit side of the article imaging device 11 includes a discharge conveyor 37 that discharges the article W after image capture. The discharge conveyor 37 is driven at a predetermined discharge speed by the rotation of a drive pulley 38 around which the discharge conveyor 37 is wound. The conveying device 12 may include a discharge device 35 shown in FIG. 1 that discharges the article W determined to be defective based on the inspection results from the inspection processing unit 60. The discharge device 35 is driven by the control unit 40 based on the inspection results from the inspection processing unit 60. The discharge device 35 removes the defective article W from the discharge conveyor 37. In the example shown in FIG. 1, the discharge device 35 is, for example, a pusher, but the method of removal can be appropriately selected, such as blowing air to remove the article W.

[0033] Also, as shown in FIG. 1, the article imaging device 11 includes N cameras 25 (where N is a natural number satisfying 2 ≦ N < M) that image the article W in the middle of the movement path MT, and a light source 24 that illuminates the article W when the N cameras 25 image the article W. Here, M is the total number of imaging times that the N cameras 25 image the article W, and is a natural number of 3 or more. Further, the article imaging device 11 includes a control unit 40 that controls the conveyance of the conveyance device 12 and the imaging of the N cameras 25.

[0034] The light source 24 illuminates the article W that moves along the movement path MT by the conveyance unit 23. The light source 24 is, for example, a surface light source. The light source 24 is disposed at a position facing the movement path MT with respect to the N cameras 25. In the present embodiment, N light sources 24 are disposed by disposing a light source for each camera 25, but a configuration may be adopted in which one light source 24 composed of one surface light source having a width extending over a region that becomes the background of the imaging areas of the N cameras 25 is disposed.

[0035] As shown in FIG. 1, the N cameras 25 are fixed at positions where they can image the article W. The N cameras 25 are arranged at intervals along the movement path MT. The camera 25 images an image of the light that has passed through the article W by the illumination of the light source 24. The N cameras 25 image the article W that moves along the movement path MT while rotating M times. Thus, the article imaging device 11 of the present embodiment is, for example, a light transmission imaging method in which the camera 25 images an image of the light that has passed through the article W having translucency. In the case of the light transmission imaging method, it is sufficient that at least the imaging target portion of the article W has translucency.

[0036] As shown in FIG. 1, the N cameras 25 take images of multiple parts of the article W that moves at a constant moving speed while rotating on its axis, at equal angular intervals (for example, 40 degree intervals) in the circumferential direction. The N cameras 25 are arranged along the moving path MT, and take images of each area obtained by dividing the entire circumferential direction of the article W that moves while rotating on its axis (more specifically, the entire outer circumferential surface of the body of the container) in the circumferential direction. That is, the article imaging device 11 obtains images of, for example, the entire circumference of the article W by dividing the imaging among the N cameras 25. Note that the N areas that the N cameras 25 take images of may be spaced apart from, or may be in contact with, or may partially overlap with, the adjacent imaging areas at both ends in the direction corresponding to the moving direction MD of the article W.

[0037] 1, an operation unit 41, a detection unit 30, and a plurality of cameras 25 are electrically connected as an input system to the control unit 40. In addition, a display unit 42, a distance adjustment device 15, a carry-in conveyor 16, a light source 24, motors 33 and 34, a discharge device 35, and a carry-out conveyor 37 are electrically connected as an output system to the control unit 40. Note that the plurality of cameras 25 are connected to the control unit 40 as an output system, since the image capture timing is controlled by the control unit 40.

[0038] The operation unit 41 shown in FIG. 1 is operated to input the imaging conditions of the article imaging device 11 and various setting values ​​(inspection condition information) required for the inspection of the inspection processing unit 60. The display unit 42 displays a guide screen when performing an input operation of the setting values ​​and the like from the operation unit 41, and displays the imaging results of the article imaging device 11 and the inspection results of the inspection processing unit 60. The control unit 40 may be configured, for example, by a personal computer. In this case, the operation unit 41 is configured by a mouse and a keyboard, and the display unit 42 is configured by a monitor. Also, a touch panel connected to the control unit 40 may be provided. The operation unit 41 and the display unit 42 may be, for example, an operation panel provided on an operation panel.

[0039] The control unit 40 controls the transport device 12 and the imaging system including the light source 24 and the camera 25. The control unit 40 includes an imaging processing circuit 50 (see FIG. 6) that controls the imaging timing of the N cameras 25 and performs image synthesis processing using a plurality of images FI captured by the N cameras 25.

[0040] Further, an inspection processing unit 60 is connected in a communicable state to the control unit 40. The inspection processing unit 60 performs an inspection process for inspecting the presence or absence of defects in the article W based on a composite image CI (see FIG. 6) acquired from the imaging processing circuit 50 in the control unit 40.

[0041] As shown in FIG. 2, the object W is, for example, a transparent container having optical transparency. In this example, the object W, which is a container, has a body part Wb whose cross section perpendicular to its axis has a circular outer shape, and a mouth part Wa located at the upper end of the body part Wb. An example of a container for the object W is, for example, a plastic bottle. The container is not limited to a plastic bottle, and may be a glass container. The container may also be a preform, which is a pre-molded part before being molded into a plastic bottle. In the case of a light transmission imaging method, the object W may be a part that is optically transparent and another part that is opaque. Furthermore, the object W may be a container or other object with an attachment such as a label attached thereto. In these cases, an area including at least a part of the label may be the object to be imaged.

[0042] As shown in Fig. 2, an article W made of a container is transported while being sandwiched between a pair of conveyor belts 31, 32. The pair of conveyor belts 31, 32 sandwich the lower part of the body portion Wb of the article W. This is because the part of the article W that is above the lower part in the height direction of the body portion Wb is to be inspected. The pair of conveyor belts 31, 32 sandwich the part of the article W other than the area to be inspected. Therefore, the part of the article W that is sandwiched between the pair of conveyor belts 31, 32 is adjusted using a height adjustment mechanism of a shift device according to the height of the article, the height of the area to be inspected, etc.

[0043] As shown in Fig. 2, the camera 25 captures an image of the body portion Wb and the mouth portion Wa of the article W. Then, the inspection processing unit 60 shown in Fig. 1 inspects the body portion Wb and the mouth portion Wa of the article W, which is an example of a container shown in Fig. 2, for defects.

[0044] The camera 25 is focused on the article W. The imaging area of ​​the camera 25 is set so that the article W is in focus no matter where the article W is located on the moving path MT. Here, the focus of the camera 25 may be, for example, the outer peripheral surface of the article W or the inner peripheral surface of the article W. One camera 25 captures images of the same article W multiple times when the article W is located at different positions on the moving path MT. The imaging area of ​​the camera 25 is set so that the article W at each position when capturing images multiple times falls within the imaging area. The adjustment of the focus of the camera 25 may be performed manually, or the camera 25 may have an automatic focusing function (autofocus function). The camera 25 has a lens group and a two-dimensional image sensor (imaging element) made of a CCD image sensor or a CMOS image sensor built in.

[0045] 4, the N cameras 25 capture images of the article W at M imaging positions #1 to #M set at imaging intervals D1 from a first position #1 to an Mth position #M. In this embodiment, the N cameras 25 capture images of the article W M times (where M is a natural number of 3 or more) from different directions in the circumferential direction to obtain M images of different parts of the article W in the circumferential direction. The N cameras 25 capture images of the article W at Ki (i=1, 2, ..., N) imaging positions obtained by equally dividing the M imaging positions #1 to #M into N groups.

[0046] Here, in this embodiment, Ki is a constant value, for example, 2 or more, and all N Ki's have the same value. In the example shown in FIG. 4, Ki=3. Therefore, in the example shown in FIG. 4, three cameras 25A to 25C (see FIG. 3) each take turns capturing images of the article W three times when it reaches each of the imaging positions #1 to #M. That is, the first camera 25A captures images of the article W a total of three times when it reaches the imaging positions #1 to #3. The second camera 25B captures images of the article W a total of three times when it reaches the imaging positions #4 to #6. The third camera 25C captures images of the article W a total of three times when it reaches the imaging positions #7 to #9.

[0047] Next, the angle of the image capturing position of the article W will be described with reference to FIG. 3. As shown in FIG. 3, in this embodiment, the direction indicated by the white arrow in FIG. 3 is the image capturing direction ID common to the N cameras 25. The surface of the article W facing the opposite direction to the image capturing direction ID as viewed from the image capturing direction ID is the front of the article W. The angle at which the article W facing the front at the image capturing position #1 is 0°. In FIG. 3 and FIG. 4, a solid arrow extending in the radial direction is attached to the position of 0° on the article W. Thereafter, the positions at which the position of 0° indicated by the arrow rotates 360° / M are set as the image capturing positions #2 to #M. In the example of M=9 shown in FIG. 3 and FIG. 4, the image capturing positions #2 to #M are set at each rotation of the article W by 40° from the image capturing position #1 at 0°. Then, the N cameras 25 capture the image of the article W at the image capturing positions #1 to #M a total of M times, so that it is possible to obtain images of the entire circumference of the article W at each 360° / M.

[0048] <Configuration of the imaging processing circuit 50> Next, the configuration of the control unit 40 and the imaging processing circuit 50 therein will be described with reference to FIG. 6. In FIG. 6, an example in which there are three cameras 25 will be described. As shown in FIG. 6, the control unit 40 includes a work position detection unit 43 and an imaging processing circuit 50. The imaging processing circuit 50 is configured, for example, by an FPGA (Field Programmable Gate Array). In FIG. 6, N (for example, three) cameras 25 take images of the article W when it is at the imaging positions #1 to #M. The imaging processing circuit 50 in the control unit 40 controls the imaging timing of the N cameras 25. The detection unit 30 detects the article W at a detection position before the article W reaches the imaging position #1. The detection position at which the detection unit 30 detects the article W is set to the imaging position #1 or a position upstream of the imaging position #1 in the moving direction MD. The detection position may be a position after the article W enters the imaging area of ​​the first camera 25A.

[0049] The work position detection unit 43 outputs a first trigger signal TS1 based on the detection signal S1 input from the detection unit 30. The first trigger signal TS1 includes a pulse having the same timing as the detection timing of the detection unit 30. The first trigger signal TS1 is input to the image capture processing circuit 50.

[0050] The imaging processing circuit 50 shown in FIG. 6 includes an imaging control unit 51, an image processing command circuit 52, and an image synthesis unit 53. The imaging control unit 51 controls the imaging of the three cameras 25. The imaging control unit 51 outputs imaging trigger signals Trg1 to Trg3 for instructing imaging to each of the three cameras 25. The imaging trigger signals Trg1 to Trg3 include imaging trigger pulses (hereinafter, also simply referred to as "trigger pulses") that determine the imaging timing of the cameras 25A to 25C as their output destinations. The imaging control unit 51 controls the imaging of the three cameras 25 by sequentially outputting the generated imaging trigger signals Trg1 to Trg3 to the three cameras 25. The imaging control unit 51 causes each of the three cameras 25 to image the article W Ki times (i = 1,..., N) (where Ki is a natural number that satisfies 1 ≦ Ki < M and the sum of N Ki values = M) based on M trigger pulses. Each of the cameras 25A to 25C images the same article W at different imaging positions Ki times (for example, 3 times, M = 9). For this reason, the imaging trigger signals Trg1 to Trg3 include Ki (for example, 3) trigger pulses each that determine the imaging timing of each of the cameras 25A to 25C. The three cameras 25 acquire a total of M captured images FI by sharing and imaging M different positions in the circumferential direction of the article W. Note that the imaging control unit 51 also performs light emission control of the light source 24 (see FIG. 1) in accordance with the imaging timing of the camera 25.

[0051] The image processing command circuit 52 commands the start of image synthesis processing to the image synthesis unit 53. The image processing command circuit 52 instructs the image synthesis unit 53 as to which captured image FI is the first (the first one) among the M captured images FI. The image processing command circuit 52 generates a reset signal RS for instructing that it is the first of the consecutive M sheets based on the detection pulse of the first trigger signal TS1. For this reason, the first trigger signal TS1 is also input to the image processing command circuit 52 that generates the reset signal RS.

[0052] The image synthesis unit 53 includes a memory (not shown) for storing an image of an area TA (hereinafter, also referred to as an "area image AI") extracted from the captured images FI sequentially input from the camera 25. The image synthesis unit 53 performs an image synthesis process for generating a composite image CI (for example, a full-circle image) based on M captured images FI (#1 to #M) input from the N cameras 25. The image synthesis unit 53 generates a composite image CI by concatenating M area images AI (#1 to #M) obtained by cutting out at least a part of an area TA of an article WI in each captured image FI based on the M captured images FI. The image synthesis unit 53 may generate two types of composite images CI1 and CI2 by synthesizing and concatenating area images AI1 and AI2 obtained by cutting out two areas TA1 and TA2 from each of the M captured images FI. Furthermore, a plurality of types of composite images CI, not limited to two types, may be generated, three or more types. The area images AI, AI1, and AI2 correspond to an example of an article area image.

[0053] The image synthesis unit 53 includes a connection control circuit 54, an area extraction circuit 55, and an area connection circuit 56. The connection control circuit 54 instructs the area extraction circuit 55 of an area address AD, which is the address of an area TA to be extracted from the captured image FI. The position of the area TA defined by the area address AD moves sequentially in accordance with the movement of the article W. The area address AD switches sequentially from No. 1 #1 to No. M #M in accordance with the movement of the article W.

[0054] The area extraction circuit 55 extracts an image from an area TA defined by an area address AD. The area extraction circuit 55 stores the extracted area image AI in memory. The memory can store M or more area images AI. The M area images AI are stored in order in area storage units corresponding to the numbers in the memory.

[0055] Furthermore, the connection control circuit 54 outputs a start signal IN to command the area connection circuit 56 to start area connection processing. When the area connection circuit 56 receives the start signal IN, it reads M area images AI#1-AI#M from M area storage units in the memory, and performs connection processing to connect the M area images AI#1-AI#M in the horizontal or vertical direction. The area connection circuit 56 outputs a composite image CI generated by the connection processing to the inspection processing unit 60. The composite image CI is, for example, a full-circumference image of the entire or part of the article W.

[0056] The inspection processing unit 60 performs inspection processing using the input composite image CI. The composite image CI is a full-circumference image that collects the entire circumference of the inspection target area of ​​the item W. The inspection processing unit 60 inspects the item W for defects by performing a full-circumference inspection of the item W using the composite image CI. The inspection processing unit 60 may be configured, for example, by a personal computer. Furthermore, the inspection processing unit 60 may be assembled integrally with the personal computer or control panel (both not shown) that configures the control unit 40.

[0057] It is not necessary that the number of times Ki of imaging of the N cameras 25 is the same. For example, when the value of M is not a natural number multiple of the value of N, the number of times of imaging of at least one camera 25 will necessarily be different from the number of times of imaging of the other cameras 25. The number of times of imaging of different values ​​may be set for each of the N cameras 25. In addition, during M times of imaging, the article W may rotate more than once or may rotate less than once. For example, when the inspection target of the article W is not the entire circumference, for example, images of 1 / 2 or 3 / 4 of the circumference of the article W may be taken. Furthermore, it is not necessary to take images of the article W at equal angular intervals (360° / M). For example, the article W may be taken at different imaging positions within a range of ±5° to ±20° with respect to 360° / M.

[0058] <Processing performed by the imaging control unit 51 and the image processing unit 53> Fig. 5 shows a timing chart relating to the processing performed by the imaging control unit 51 and the image synthesis unit 53. The timing chart shows the generation of N imaging trigger signals Trg1 to TrgN each including Ki trigger pulses that determine the imaging timing of the N cameras 25 for each camera 25, using the detection pulse of the first trigger signal TS1 as a trigger. Fig. 5 shows, as an example, an example in which N=3 and Ki=3, where the number of cameras 25 is three and each camera 25 captures images three times.

[0059] 5, the imaging control unit 51 generates N (e.g., three) imaging trigger signals Trg1 to Trg3. First, the imaging control unit 51 generates the first imaging trigger signal Trg1 using as a trigger a pulse of a first trigger signal TS1 based on a detection signal S1 in which the detection unit 30 detects an article W. The first imaging trigger signal Trg1 includes Ki (e.g., three) trigger pulses.

[0060] The first trigger pulse in the imaging trigger signal Trg1 is generated at the same timing as the pulse of the first trigger signal TS1, and then the second and subsequent trigger pulses are generated sequentially from the first trigger pulse for each imaging cycle Tc. In this way, the first imaging trigger signal Trg1 is generated, which includes Ki trigger pulses that determine the timing of Ki imaging operations of the first camera 25A.

[0061] The second imaging trigger signal Trg2 is generated as follows. The imaging control unit 51 uses a pulse of the second trigger signal TS2 generated at a timing corresponding to the Ki+1th (e.g., fourth) trigger pulse in the first imaging trigger signal Trg1 as a trigger to sequentially generate Ki (e.g., three) trigger pulses for each imaging cycle Tc. In this way, the second imaging trigger signal Trg2 is generated, which includes Ki trigger pulses synchronized with the last trigger pulse in the first imaging trigger signal Trg1.

[0062] The third imaging trigger signal Trg3 is generated as follows. The imaging control unit 51 uses a pulse of the third trigger signal TS3 generated at a timing corresponding to the Ki+1th (e.g., fourth) trigger pulse in the second imaging trigger signal Trg2 as a trigger to sequentially generate Ki (e.g., three) trigger pulses for each imaging cycle Tc. In this way, the third imaging trigger signal Trg3 is generated, which includes Ki trigger pulses synchronized with the last trigger pulse in the second imaging trigger signal Trg2.

[0063] The imaging control unit 51 outputs the N imaging trigger signals Trg1 to Trg3 to the N cameras 25 as output destinations so that the trigger pulses are output sequentially in the order of generation. In this way, the imaging control unit 51 controls the imaging timing of the N cameras 25. The imaging control unit 51 may also generate the second imaging trigger signal Trg2 and the third imaging trigger signal Trg3 using the detection pulse of the first trigger signal TS1 as a trigger. That is, the imaging control unit 51 generates the second imaging trigger signal Trg2 by using the pulse of the first trigger signal TS1 as a trigger and generating Ki (e.g., three) trigger pulses for each imaging cycle Tc at a timing when a time equivalent to Ki times the imaging cycle Tc (e.g., 3Tc) has elapsed. Furthermore, the imaging control unit 51 generates the third imaging trigger signal Trg3 by using the pulse of the first trigger signal TS1 as a trigger and generating Ki (e.g., three) trigger pulses for each imaging cycle Tc at a timing when a time equivalent to 2Ki times the imaging cycle Tc (e.g., 6Tc) has elapsed.

[0064] Furthermore, the imaging control unit 51 generates N light emission control signals each including Ki light emission trigger pulses that determine the light emission timing for making the N light sources 24 emit light in accordance with the imaging timing of the N cameras 25 based on the pulse of the first trigger signal TS1. The imaging control unit 51 sequentially outputs the N light emission control signals to the N light sources 24 in the order in which they were generated. The N light sources 24 emit light in turn at the timing of the light emission trigger pulse in the light emission control signal input to each of them. For example, the N light sources 24 may emit light once during the period of Ki imaging of the corresponding camera 25, or may emit light Ki times, once for each imaging.

[0065] In this way, the N (e.g., three) cameras 25A-25C each take Ki images of the article W at the imaging positions #1-#M (e.g., #9) to capture M images in total. In detail, the first camera 25A captures the article W at the imaging positions #1-#3 by capturing Ki images (e.g., three images). The second camera 25B captures the article W at the imaging positions #4-#6 by capturing Ki images (e.g., three images). The third camera 25C captures the article W at the imaging positions #7-#9 by capturing Ki images (e.g., three images). The N cameras 25 capture the outer periphery of the article W from different directions of 360° / M (e.g., 40°) each in total M images (e.g., nine images) during a rotation period Tr in which the article W makes one rotation on its axis.

[0066] 5, during a rotation period Tr, a total of M (e.g., nine) captured images FI are input to an imaging processing circuit 50 (see FIG. 6 for all) from N cameras 25. In detail, the imaging processing circuit 50 first inputs three captured images FI#1 to FI#3 from the first camera 25A, then inputs three captured images FI#4 to FI#6 from the second camera 25B, and further inputs three captured images FI#7 to FI#9 from the third camera 25C.

[0067] These M captured images FI are input to a region extraction circuit 55 in the image capture processing circuit 50. The region extraction circuit 55 extracts M region images AI including at least a part of the article WI by cutting out portions designated by the regions TA of #1 to #M from the captured images FI#1 to FI#M, respectively. The M region images AI are stored sequentially in a predetermined storage area of ​​the memory.

[0068] The area connection circuit 56 inputs a start signal IN slightly earlier than the imaging processing circuit 50 finishes inputting all of the M captured images FI. The area connection circuit 56 performs area connection processing IC (see FIG. 5) commanded by the start signal IN. That is, the area connection circuit 56 connects the M area images AI, for example, in the horizontal direction, to generate one composite image CI (for example, a panoramic image). The imaging processing circuit 50 outputs the composite image CI to the inspection processing unit 60.

[0069] The inspection processing unit 60 performs an inspection process for inspecting the article W based on the input composite image CI. The inspection processing unit 60 inspects, for example, whether there are defects in the article W. For example, the inspection processing unit 60 performs a comparison inspection, a character recognition inspection, or a black foreign matter inspection, etc. As an example, in the case of a comparison inspection, the inspection processing unit 60 extracts a difference from the comparison result between the composite image CI and a good product image which is an image of the entire circumference of the good product article W. The inspection processing unit 60 sets the region extracted as the difference as a defect candidate. Then, the inspection processing unit 60 determines whether the defect candidate is a defect based on determination conditions such as the shape and size of the region of the defect candidate. The inspection processing of the inspection processing unit 60 may be performed by AI (Artificial Intelligence). For example, by inputting the composite image CI or the image of the defect candidate into a learned model that has learned an image of a defective article W including a defect of the article W and an image of a good article W, it may be determined whether there is a defect or whether it is a defect. Note that the defects include scratches on the article W itself, foreign matter mixed in the forming material of the article W, foreign matter in the container when the article W is a container, foreign matter in the contents of the container, scratches, tears, misalignment of the label attached to the container, printing mistakes of the characters printed on the container or the label, etc. Thus, the defect may be any inspection target for which the article W is regarded as a defective product.

[0070] <Operation of the First Embodiment> Next, the operation of the first embodiment will be described with reference to FIGS. 4 to 6 and the like. As shown in FIG. 4, N (for example, 3) cameras 25A to 25C share M imaging operations to image the article W Ki times each. For this reason, each of the cameras 25A to 25C only needs to perform Ki times (Ki < M) of imaging. In this case, compared with the configuration in which one camera 25 performs M times of imaging, since the camera 25 only needs to be able to image a narrow range corresponding to Ki times in the movement path MT, the imaging region of the camera 25 can be set narrower. Therefore, even if a general-purpose camera is used for the camera 25, it becomes easier to obtain an imaging image FI with the required image resolution.

[0071] On the other hand, for example, in the conveying device 12 in which the rotation speed and the moving speed are in a proportional relationship, the moving distance is shortened by rotating the article W at high speed for the purpose of high-speed processing, so the imaging area of ​​the camera 25 can be narrowed. This ensures the image resolution of the captured image FI. However, when a general-purpose camera is used as the camera 25, there is a limit to how fast the imaging cycle can be, so it is necessary to use a special camera such as a high-rate camera capable of high-speed imaging. With the configuration of this embodiment, the number of times of imaging per camera is, for example, M / N, by sharing the work among N cameras 25. Therefore, it is also permissible to rotate the article W at a low speed. Therefore, even if a general-purpose camera with a longer imaging cycle than a special camera capable of high-speed imaging is used, the number of images captured at different positions of the article W can be increased while ensuring the necessary image resolution.

[0072] For example, when the number of images taken per object is increased in order to increase the angular resolution of the composite image CI, a general-purpose camera can be used without using a special camera. For example, in a configuration in which one camera 25 takes M images, in the case of 1000 bpm and 12 connections, the minimum camera frame rate required is 200 fps, which can be handled by a general-purpose camera. However, in the case of 1000 bpm and 36 connections, a camera frame rate of 600 fps is required, which cannot be handled by a general-purpose camera.

[0073] In contrast, in the configuration using three cameras 25A to 25C as in this embodiment, in the case of 1000 bpm and 36 connections, the camera frame rate is 200 fps, so that even a general-purpose camera can be used.

[0074] Furthermore, according to the article imaging device 11 of this embodiment, the rotation speed can be reduced, and the conveying device 12 can be simplified. For example, in a configuration in which one camera 25 captures images M times, the rotation speed is, for example, 23 rotations / second in the case of 1000 bpm and 12-linked cameras. In the case of a configuration using three cameras 25A-25C as in this embodiment, even under the same conditions of 1000 bpm and 12-linked cameras, the rotation speed is, for example, 7.5 rotations / second, which is 1 / N.

[0075] In addition, if a special camera capable of high-speed imaging is used for the camera 25, while ensuring the required image resolution, the number of imaging shots for imaging different positions of the article W can be further increased. For example, by increasing the number of imaging times M of the article W to increase the number of connections of the region image AI, a composite image CI (region connection image) with high angular resolution can be generated. Therefore, the inspection accuracy of the article W can be further improved.

[0076] In addition, the imaging control unit 51 sequentially generates Ki (for example, 3) trigger pulses for each imaging period Tc using the detection pulse of the first trigger signal TS1 based on the detection signal S1 that detects the article W as a trigger. Then, imaging trigger signals Trg1 to Trg3 including Ki trigger pulses are output to N (3) cameras 25A to 25C in the order of generation of the trigger pulses. Since synchronization is maintained to keep the trigger pulses at the imaging period Tc among the imaging trigger signals Trg1 to Trg3, even if N cameras 25 share M imaging operations, the continuity of the M acquired imaging images FI is maintained.

[0077] Next, the article imaging method of the present embodiment will be described. The article imaging method using the article imaging apparatus 11 including N (where N is a natural number satisfying 2 ≤ N < M) cameras 25 and the detection unit 30 of the present embodiment includes the following (A) to (C). (A) Generating imaging trigger signals Trg1 to TrgN including M trigger pulses for determining a total of M imaging timings at which N cameras 25 image based on the detection pulse. (B) Each of the N cameras 25 performs imaging of the article W for Ki times (i = 1,..., N) (where Ki is a natural number satisfying 1 ≤ Ki < M and the total value of N Ki's = M) based on the M trigger pulses. (C) Generating a composite image CI by synthesizing into one a region image AI including at least a part of the article WI among a total of M images FI obtained by performing Ki times of imaging shared by the N cameras 25.

[0078] <Effect of the Embodiment> According to the embodiments described in detail above, the following effects can be obtained. (1) The article imaging device 11 includes N cameras 25 (where N is a natural number satisfying 2 ≤ N < M), a detection unit 30, an imaging control unit 51, and an image synthesis unit 53. The N cameras 25 acquire M images of different portions in the circumferential direction of the article W by imaging the article W M times (where M is a natural number of 3 or more) from relatively different directions in the circumferential direction, and share the M times of imaging of the article W. The detection unit 30 detects the article W at a detection position before reaching the imaging position of the first time among the M times. The imaging control unit 51 generates imaging trigger signals Trg1 to TrgN including M trigger pulses that determine the imaging timings of a total of M times of imaging performed by the N cameras 25 based on detection pulses based on the detection results of the detection unit 30. The imaging control unit 51 causes each of the N cameras 25 to image the article W Ki times (i = 1,..., N) (where Ki is a natural number satisfying 1 ≤ Ki < M and the total value of the N Ki's = M) that each shares. The image synthesis unit 53 synthesizes into one an article image region including at least a part of the article W among the total M images obtained by performing the Ki times of imaging shared by the N cameras 25 to generate a synthesized image CI.

[0079] According to this configuration, the M images acquired by imaging the article W from different directions in the circumferential direction with the cameras 25 are acquired by sharing the imaging of the article W with a plurality (N) of cameras 25. Therefore, it is possible to cope with a decrease in the relative rotation speed between the article W and the cameras 25, that is, a decrease in the rotation speed of the article W itself. Thus, while ensuring the required image resolution, for example, it is possible to increase the number of imaging times for imaging different positions of the article W even with the imaging period of the cameras 25 composed of general-purpose cameras. Further, when using a special camera such as a high-rate camera capable of high-speed imaging as the camera 25, while ensuring the required image resolution, it is possible to further increase the number of imaging times for imaging different positions of the article W by shortening the imaging period.

[0080] (2) The N cameras 25 are fixed at positions where they can image the article W, and image the article W moving along the moving path MT while rotating M times. According to this configuration, the N fixed cameras 25 image the article W moving along the moving path MT while rotating, so the article imaging device 11 can be configured more simply than a configuration in which the cameras 25 move around the article W.

[0081] (3) The N cameras 25 are arranged at intervals along the moving path MT. The N cameras 25 take images of the article W at Ki (i=1, ..., N) imaging positions obtained by equally dividing the M imaging positions #1 to #M set at the imaging interval D1 from the first position to the Mth position into N groups. According to this configuration, the multiple (N) cameras 25 equally take M images Ki times (the number of imaging positions Ki), so that the image processing between the cameras 25 can be the same and individual processing is not required. In addition, the maximum distance of the N cameras 25 can be relatively small in the imaging distance required to fit the Ki imaging positions within the imaging area of ​​the camera 25. Therefore, it is easy to obtain the required image resolution in all of the N cameras 25.

[0082] (4) The imaging control unit 51 generates N imaging trigger signals Trg1 to TrgN, each including M trigger pulses Ki, at timing when M portions positioned at equal intervals in the circumferential direction of the article W can be imaged from the front. The imaging control unit 51 outputs the N imaging trigger signals Trg1 to TrgN to the N cameras 25. With this configuration, a composite image CI, such as a full-circumference image suitable for inspection, can be acquired.

[0083] (5) The inspection device 10 includes an article imaging device 11 and an inspection processing unit 60 that inspects the article W based on a composite image input from the article imaging device 11. According to this configuration, the article W can be inspected using a composite image CI obtained by combining a required number of images with a required image resolution, thereby ensuring the required inspection accuracy.

[0084] An article imaging method using an article imaging apparatus 11 including N cameras 25 (where N is a natural number satisfying 2 ≤ N < M) and a detection unit 30 that share M times of imaging (where M is a natural number of 3 or more) for imaging an article W from relatively different directions in the circumferential direction. The N cameras 25 acquire M images of different parts of the article W in the circumferential direction by sharing the M times of imaging. The detection unit 30 detects the article W at a detection position before reaching the imaging position of the first imaging among the M times of imaging and outputs a detection pulse. This article imaging method includes the following (A) to (C). (A) Generating imaging trigger signals Trg1 to TrgN including M trigger pulses for determining the total M imaging timings at which the N cameras 25 image based on the detection pulse. (B) The N cameras 25 each perform Ki times (i = 1,..., N) (where Ki is a natural number satisfying 1 ≤ Ki < M and the sum of the N Ki values = M) of imaging of the article W based on the M trigger pulses. (C) Generating a composite image CI by combining into one an article image region including at least a part of the article W among the total M images obtained by performing the Ki times of imaging shared by the N cameras 25.

[0085] According to this method, since the N cameras 25 share the imaging of the article W from a plurality of different directions in the circumferential direction, it is possible to increase the number of imaging times for imaging different positions of the article W while ensuring the required image resolution. Also, when using a special camera capable of high-speed imaging, it is possible to further increase the number of imaging times for imaging different positions of the article W while ensuring the required image resolution.

[0086] (Second Embodiment) Next, a second embodiment will be described with reference to Figs. 7 and 8. In the second embodiment, the arrangement of the N cameras 25 relative to the moving path MT is different from that of the first embodiment. The basic configuration of the article imaging device 11 is the same as that of the first embodiment. The layout of the N cameras 25 and the imaging control content of the imaging control unit 51 due to the difference in the layout are different from those of the first embodiment. Note that in Fig. 7, the light source 24 that illuminates the article W that is the imaging target of the camera 25 is omitted. For example, the light source 24 may be arranged at a position facing the camera 25 across the moving path MT.

[0087] As shown in FIG. 7, the moving path MT along which the conveying device 12 moves the article W is a straight path as in the first embodiment. The N cameras 25 are arranged in a zigzag pattern alternately positioned at a predetermined distance on both sides of the moving path MT. In the example shown in FIG. 7, the second camera 25B is arranged on the opposite side of the moving path MT to a position located 1.5 times the imaging interval D1, which is the interval between the imaging positions #1 to #9, from the first camera 25A along the moving path MT. Furthermore, the third camera 25C is arranged on the opposite side of the moving path MT to a position located 1.5 times the imaging interval D1 from the second camera 25B along the moving path MT.

[0088] Generalizing this, the N cameras 25 are arranged in a zigzag pattern under the following arrangement conditions. As shown in Fig. 7, the N cameras 25 are the i-th (i = 1, ..., N) cameras 25 in order from the earliest one that captures an image of the same item W for the first time. The number of times Ki that the N cameras 25 capture images of the item W is the same. The next (i + 1)-th camera 25 is arranged at a position on the opposite side of the movement path MT from the i-th camera 25, which is located a distance Ki / 2 * D1 along the movement path MT. The N cameras 25 are arranged in a zigzag pattern according to this arrangement rule.

[0089] Here, the pitch of the N cameras 25 in the first embodiment is indicated as D1*Ki. When Ki=3, the pitch of the cameras 25 is 3*D1. In contrast, in this embodiment, in which the N cameras 25 are arranged in a zigzag pattern, the pitch of the cameras 25 is D1*Ki / 2. When Ki=3, the pitch of the cameras 25 is 3 / 2*D1. Therefore, according to the zigzag layout of this embodiment, the length dimension required to arrange the N cameras 25 along the movement path MT is half that of the layout of the first embodiment in a single row on one side.

[0090] Fig. 8 is a timing chart when the imaging control unit 51 controls the imaging of the N (three) cameras 25A to 25C in Fig. 7. As shown in Fig. 8, the imaging control unit 51 generates Ki trigger pulses to be output to the i-th camera 25 and Ki trigger pulses to be output to the next camera 25 in sequence, at a timing shifted in phase by an adjustment time. Here, the adjustment time is a time for adjusting the timing by the i-th and (i+1)-th cameras 25 capturing images from opposite sides of the moving path MT, and is set to a value smaller than the imaging period Tc.

[0091] As shown in Fig. 8, the adjustment time is Tc / 2. A pulse of a second trigger signal TS2 is generated when time Tc / 2 has elapsed since the second trigger pulse in the imaging trigger signal Trg1. This pulse is used as a trigger to generate three trigger pulses of the imaging trigger signal Trg2. Similarly, a pulse of a third trigger signal TS3 is generated when time Tc / 2 has elapsed since the second trigger pulse in the imaging trigger signal Trg2. This pulse is used as a trigger to generate three trigger pulses of the imaging trigger signal Trg3.

[0092] The generation period of the three trigger pulses of the imaging trigger signal Trg1 thus generated corresponds to the imaging period required for the first camera 25A to capture Ki images. Similarly, the generation period of the three trigger pulses of the imaging trigger signal Trg2 corresponds to the imaging period required for the second camera 25B to capture Ki images.

[0093] 8, the generation period of the imaging trigger signal Trg1 and the generation period of the imaging trigger signal Trg2 overlap by Tc / 2. Similarly, the generation period of the imaging trigger signal Trg2 and the generation period of the imaging trigger signal Trg3 overlap by Tc / 2. Therefore, the imaging period in which the first camera 25A captures images three times and the imaging period in which the second camera 25B captures images three times partially overlap by the time Tc / 2. Similarly, the imaging period in which the second camera 25B captures images three times and the imaging period in which the third camera 25C captures images three times partially overlap by the time Tc / 2.

[0094] To generalize this, the imaging period required for the i-th camera 25 to capture Ki images partially overlaps with the imaging period required for the adjacent (i+1-th) camera 25 to capture Ki images. The overlap time is (Ki / 2-1)*Tc. The imaging control unit 51 generates N imaging trigger signals Trg1 to TrgN, each including Ki M trigger pulses, at a timing that satisfies this condition.

[0095] The image synthesis unit 53 inputs images in the order of #1, #2, #2.5, #3, #3.5, #4, #4.5, #5, and #6 from the N cameras 25. The image synthesis unit 53 generates a synthetic image CI by synthesizing the input images in the order of #1, #2, #3, #4, #5, #6, #2.5, #3.5, and #4.5.

[0096] According to the second embodiment, the following effects can be obtained. (7) The N cameras 25 are numbered i (i=1, ..., N) in order from the earliest timing of capturing an image of the same article W for the first time. The imaging control unit 51 generates M trigger pulses at a timing when the imaging period required for the i-th camera 25 to capture Ki images partially overlaps with the imaging period required for the adjacent camera 25 to capture Ki images. With this configuration, the arrangement space for the N cameras 25 arranged around the movement path MT can be reduced in the direction along the movement path MT. Therefore, the article imaging device 11 can be made smaller.

[0097] (8) The N cameras 25 are arranged in a zigzag pattern, alternately positioned at a predetermined distance on both sides of the moving path MT. The imaging control unit 51 generates Ki trigger pulses to be output to the i-th camera 25, and Ki trigger pulses to be output to the next camera 25 in order, at timings shifted in phase by an adjustment time set to a value smaller than the imaging period for timing adjustment due to both cameras 25 capturing images from opposite sides of the moving path MT. According to this configuration, since the N cameras 25 are arranged in a zigzag pattern, the imaging periods of the cameras can be partially overlapped, and imaging timing can be aligned among the N cameras 25. For example, even with a general-purpose camera, the number of images taken of different positions of the article W can be increased while ensuring the required image resolution.

[0098] Third embodiment Next, a third embodiment will be described with reference to Figs. 9 and 10. In the third embodiment, the arrangement of the N cameras 25 relative to the moving path MT is different from each of the above-mentioned embodiments. The basic configuration of the article imaging device 11 is the same as that of the first embodiment. The layout of the N cameras 25 and the imaging control content of the imaging control unit 51 due to the difference in the layout are different from those of the first embodiment. Note that in Fig. 9, the light source 24 that illuminates the article W that is the imaging target of the camera 25 is omitted. For example, the light source 24 may be arranged at a position facing the camera 25 across the moving path MT.

[0099] As shown in Fig. 9, the movement path MT has N movement path segments MT1 to MT3 along which the article W moves in a straight or curved path so as to pass through imaging positions Ki times where images are captured by the N cameras 25. The N movement path segments MT1 to MT3 are not paths arranged in a straight line. In other words, this embodiment is an example in which the movement direction MD shown in Figs. 1 and 6 changes depending on the imaging positions.

[0100] 9, the N cameras 25 are arranged such that their optical axes C1 to C3 intersect with an imaginary line connecting the first imaging position and the Ki-th imaging position at an angle within an allowable range of ±10° with respect to a right angle. The angle formed by the optical axes C of the N cameras 25 is set to an angle according to 360° / M.

[0101] In the example shown in FIG. 9, each of the three cameras 25A to 25C is disposed in such a direction that the optical axes C1 to C3 of the cameras intersect with a virtual straight line connecting the first imaging position and the Ki-th imaging position at an angle within the allowable range of ±10° with respect to the right angle. In more detail, the first camera 25A is disposed in such a direction that the optical axis C1 of the first camera intersects with a virtual straight line MT1 connecting the first imaging position #1 and the third imaging position #3 at an angle within the allowable range of ±10° with respect to the right angle. The second camera 25B is disposed in such a direction that the optical axis C2 of the second camera intersects with a virtual straight line MT2 connecting the first imaging position #3 and the third imaging position #5 at an angle within the allowable range of ±10° with respect to the right angle. The third camera 25C is disposed in such a direction that the optical axis C3 of the third camera intersects with a virtual straight line MT3 connecting the first imaging position #5 and the third imaging position #7 at an angle within the allowable range of ±10° with respect to the right angle.

[0102] As shown in Fig. 9, the angle formed by the optical axes C1 to CN of the N cameras 25 is set to an angle corresponding to 360° / M. In the example shown in Fig. 9, the angles θ1, θ2 formed by the optical axes C1 to C3 of the three cameras 25A to 25C are set to about 40°, which is an angle corresponding to 360° / M. Here, the "angle corresponding to 360° / M" may be 360° / M itself, or may be an angle within an allowable range of ±10° with respect to 360° / M.

[0103] Fig. 10 is a timing chart when the imaging control unit 51 controls the imaging of N (three) cameras 25A to 25C. As shown in Fig. 10, the imaging control unit 51 generates the first (1st) trigger pulse of the Ki trigger pulses to be output to the next (i+1th) camera 25 in the sequence at the same timing as the last trigger pulse of the Ki trigger pulses to be output to the i-th camera 25.

[0104] 10, a pulse of the second trigger signal TS2 is generated at the same timing as the third (last) trigger pulse in the imaging trigger signal Trg1. This pulse is used as a trigger to generate the first (initial) trigger pulse of the three trigger pulses of the imaging trigger signal Trg2. Similarly, a pulse of the third trigger signal TS3 is generated at the same timing as the last (third) trigger pulse in the imaging trigger signal Trg2. This pulse is used as a trigger to generate the first trigger pulse of the three trigger pulses of the imaging trigger signal Trg3.

[0105] The generation period of three trigger pulses of the imaging trigger signal Trg1 corresponds to the imaging period required for the first camera 25A to capture Ki images. Similarly, the generation period of three trigger pulses of the imaging trigger signal Trg2 corresponds to the imaging period required for the second camera 25B to capture Ki images. Therefore, the imaging period required for the first camera 25A to capture Ki images partially overlaps with the imaging period required for the second camera 25B to capture Ki images.

[0106] The imaging control unit 51 simultaneously performs the Ki-th (last) imaging by the i-th camera 25 and the first (initial) imaging by the next (i+1-th) camera 25 in the sequence at the same timing. In this case, the last imaging by the i-th camera 25 and the first imaging by the next (i+1-th) camera 25 are simultaneously performed. In other words, the imaging cycle of the i-th camera 25 and the imaging cycle of the i+1-th camera 25 partially overlap at the time when the imaging is performed simultaneously.

[0107] According to the third embodiment, the following effects can be obtained. (9) The moving path MT has N moving path portions MT1 to MT3 that move the article W along a straight or curved path so as to pass through the imaging positions Ki times where the N cameras 25 respectively capture images. Each of the N cameras 25 is disposed in such a direction that the optical axis of each of the cameras 25 intersects with a virtual line connecting the first imaging position and the Ki imaging position at an angle within an allowable range of ±10° with respect to a right angle, for example. The angle formed by the optical axes C of the N cameras 25 is set to an angle according to 360° / M. According to this configuration, the imaging periods of the N cameras 25 can be partially overlapped, so that the cameras 25 can be disposed close to each other. Therefore, the article imaging device 11 can be made compact.

[0108] (Fourth embodiment) Next, a fourth embodiment will be described with reference to Fig. 11 to Fig. 13. The fourth embodiment employs imaging control in which the imaging control unit 51 determines the imaging timing with the surface of the article W facing the camera 25 regarded as the front.

[0109] In each of the above-described embodiments, the front of the article W when viewed from a direction parallel to the optical axes C1-C3 of the cameras 25A-25C is regarded as the front of the article W, and the N (e.g., three) cameras 25A-25C set the positions of the article W as imaging positions #1-#M when the target circumferential position of the article W faces the front perpendicular to the direction parallel to the optical axes C1-C3. The imaging control unit 51 generates imaging trigger signals Trg1-Trg3 so that the cameras 25 can image the article W when it is at the imaging positions #1-#M.

[0110] As shown in Fig. 11, the circumferential positions at which the article W faces the camera 25 (25A) at Ki (e.g., three) imaging positions #1 to #3 are different in the strict sense. That is, the position indicated by the black triangle mark attached to the article W in Fig. 11 is the front face of the article W facing the camera 25. In this embodiment, the imaging control unit 51 causes the camera 25 to capture an image at the timing when the center of the front face indicated by the black triangle mark becomes the target angle, with the position at which the article W faces the camera 25 being the center of the front face.

[0111] 12, in an example with three cameras 25A to 25C, an article W at imaging positions #3 and #5 faces the two cameras 25 in different directions as indicated by black triangle marks. Therefore, even if the moving path MT is a straight path similar to that in the first embodiment, the article W at the same imaging positions #3 and #5 can be imaged simultaneously or almost simultaneously with a short time difference less than the imaging period Tc by the two cameras 25. In other words, the article W at imaging position #3 can be imaged simultaneously or almost simultaneously by the first camera 25A and the second camera 25B, and the article W at imaging position #5 can be imaged simultaneously or almost simultaneously by the second camera 25B and the third camera 25C.

[0112] However, in order to generate imaging trigger signals Trg1 to Trg3 with a trigger pulse for each imaging cycle Tc, it is necessary to set the angle between the directions in which the two cameras 25 face at imaging positions #3 and #5 to 360° / M or an angle close to that. Therefore, the arrangement pitch and focal length of the cameras 25 are adjusted so that the angle becomes 360° / M or an angle close to that.

[0113] FIG. 13 is an example of a timing chart when the imaging control unit 51 controls the imaging of N (three) cameras 25A to 25C. FIG. 13 may be basically the same as the timing chart shown in the second embodiment. For example, the imaging control unit 51 generates the first (first) trigger pulse of Ki trigger pulses to be output to the next (i+1) camera 25 at the same timing as the last trigger pulse of Ki trigger pulses to be output to the i-th camera 25. Note that the third trigger pulse of the first imaging trigger signal Trg1 and the first trigger pulse of the second imaging trigger signal Trg2 do not need to coincide. The camera 25A images the article W at the imaging position #3 based on the third trigger pulse of the first imaging trigger signal Trg1, and the camera 25B images the article W at the point of time when the camera 25B rotates beyond the imaging position #3. This increases the degree of freedom of the installation position of the cameras 25.

[0114] The generation period of three trigger pulses of the imaging trigger signal Trg1 corresponds to the imaging period required for the first camera 25A to capture Ki images. Similarly, the generation period of three trigger pulses of the imaging trigger signal Trg2 corresponds to the imaging period required for the second camera 25B to capture Ki images. Therefore, the imaging period required for the first camera 25A to capture Ki images partially overlaps with the imaging period required for the second camera 25B to capture Ki images. Similarly, the imaging period required for the second camera 25B to capture Ki images partially overlaps with the imaging period required for the third camera 25C to capture Ki images. In detail, at the simultaneous imaging time when the two cameras 25 simultaneously capture the same object W at the same imaging position, the imaging periods of the two cameras 25 partially overlap.

[0115] Therefore, according to this fourth embodiment, in addition to obtaining the effects (1) to (6) of the first embodiment, even if the movement path MT is a straight path and N cameras 25 are arranged in a row on one side, the imaging periods of two adjacent cameras 25 can be partially overlapped, as in the second embodiment, so that the effect (7) of the second embodiment can be obtained.

[0116] The embodiment is not limited to the above, and may be modified in the following manner. In each of the above-described embodiments, the generation time of the trigger pulse that determines the imaging timing may be adjusted using the rotation detection signal ES (e.g., an encoder signal) of the rotation detection units E1 and E2. For example, as shown in FIG. 14, the imaging processing circuit 50 may be provided with a correction circuit that corrects the pulse generation time determined by the imaging control unit 51 for each fixed imaging cycle Tc using the rotation detection signal ES that detects the rotation of the driving source of the conveying device 12. The rotation detection signal ES uses, for example, the rotation detection signals ES1 and ES2 from the rotation detection units E1 and E2 that detect the rotation of the motors 33 and 34 that are the driving sources of the conveying unit 23 shown in FIG. 1. For example, the imaging control unit 51 includes a pulse generation time setting unit with low time resolution that can set the time when the trigger pulse is generated, and generates a trigger pulse for each imaging cycle Tc by setting the value of the imaging cycle Tc in the pulse generation time setting unit. The correction circuit has a higher time resolution than the pulse generation time setting unit, and can correct the pulse generation time that is scheduled to be generated by the pulse generation time setting unit with high time resolution. By correcting the trigger pulse generation time using the correction circuit in this manner, the period of the trigger pulse may be changed for each of the cameras 25A to 25C, or the period of the trigger pulse may be changed between Ki imaging operations of the same camera 25.

[0117] In each of the above embodiments, the number of times Ki that each of the N cameras 25 captures an image is not limited to Ki=3, but may be a constant value of 2 or more. For example, all N Ki may be 2 (constant value "2"), all 4 (constant value "4"), or all 5 (constant value "5"). Furthermore, all N Ki may be a constant value of 6 or more, for example, all N Ki may be 10 or all 20.

[0118] In each of the above-described embodiments, the number (N) of cameras 25 that share the M number of images may be any number other than 3. For example, the number N of cameras 25 may be N=2, N=4, N=5, or N=6.

[0119] The number of times Ki that the N cameras 25 capture images may differ between the cameras 25. At least one of the number of times Ki of the N cameras 25 capture images may be different from the others. For example, the number of times Ki of the N cameras 25 may all be different, or only one or two of the number of times Ki of the N cameras 25 may be different from the others. Also, there may be two or three groups of N cameras 25 with different Ki values.

[0120] In the first to third embodiments, the imaging timing of N cameras 25 (for example, three cameras) may be controlled with the imaging timing of the fourth embodiment. That is, in the layout of N cameras 25 in the first to third embodiments, the position where the article W faces the camera 25 may be set as the front, and the imaging control unit 51 may generate imaging trigger signals Trg1 to TrgN. According to this configuration, an area TA closer to the front of the article WI can be extracted from M captured images FI to obtain an area image AI closer to the front. Therefore, a full-circle image closer to the front can be obtained as a composite image CI. Note that in each of the above embodiments, it is possible to deal with a low time resolution, such as by making the period Tc for generating trigger pulses constant, but in this modified example, there may be cases where it is necessary to change the period when generating trigger pulses. In that case, it is necessary to set the time resolution high. In such a case, the generation timing of the trigger pulse may be corrected using the imaging processing circuit 50 shown in FIG. 14.

[0121] In each embodiment, the intervals between the N cameras 25 do not have to be equal along the movement path MT. Also, the imaging intervals D1 do not have to be all the same. The camera 25 may capture Ki images of the article W from directly in front of it by changing the direction of the camera 25 to track the article W as it moves.

[0122] The conveying unit 23 is not limited to the belt conveying type, and other conveying types can be adopted. For example, the conveying unit 23 may be a rotary type conveying unit. The rotary type conveying unit 23 moves the article W along the moving path MT, which is a circular arc path, while rotating the article W in a hanging state in which the mouth portion Wa of the article W is sucked or gripped.

[0123] The N cameras 25 may be configured to move relative to the article W in the circumferential direction. In this case, the article W may be placed at a predetermined position and in a stationary state, or may be configured to move along the moving path MT without rotating. In the latter case, the N cameras 25 may be configured to move relative to the article W in the circumferential direction while moving along the moving path MT together with the movement of the article W, thereby capturing images of the article W Ki times from different directions.

[0124] The light source 24 may be configured to irradiate light from the bottom side of the article W moving through the imaging area in the middle of the imaging passage 20, or from the mouth Wa side. In the former case, the transport conveyor 17 may be eliminated, or the transport conveyor 17 may be made of a light-transmitting material, or a window for irradiating light may be provided in the article placement area of ​​the transport conveyor 17.

[0125] In each of the above embodiments, the object imaging device 11 may be of a light reflection imaging type in which the light source 24 is disposed on the camera 25 side with respect to the moving path MT, and the N cameras 25 capture images of light reflected from the surface of the object W by the light from the light source 24. In this case, the object W may be an opaque object.

[0126] The use of the article imaging device 11 is not limited to inspection such as appearance inspection of an article, but may also be used to inspect changes in the speed of an article W, the trajectory of an article W, and the like. The imaging processing circuit 50 may be equipped with a CPU and a memory to execute software processing. Furthermore, the imaging processing circuit 50 is not limited to this. That is, the imaging processing circuit 50 may be equipped with a processing circuit having any of the following configurations (a) to (c). (a) A processing circuit equipped with one or more processors that execute various processes according to a computer program. The processor includes a CPU and memories such as RAM and ROM. The memory stores program codes or instructions that are configured to cause the CPU to execute the processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. (b) A processing circuit equipped with one or more dedicated hardware circuits that execute various processes. An example of a dedicated hardware circuit is an application-specific integrated circuit, i.e., ASIC. (c) A processing circuit equipped with a processor that executes part of the various processes according to a computer program and a dedicated hardware circuit that executes the remaining processes of the various processes. [Explanation of symbols]

[0127] 10... inspection device, 11... article imaging device, 12... conveying device, 13... carry-in device, 14... carry-out device, 15... interval adjustment device, 16... carry-in conveyor, 17... conveying conveyor, 20... imaging passage, 21, 22... belt device, 23... conveying section, 24... light source, 24A... first light source, 24B... second light source, 24C... third light source, 25... camera, 25A... first camera, 25B... second camera, 25C... third camera, 26... shift device, 28... pulley, 2 9...pulley, 30...detection unit, 31, 32...conveyor belt, 31a, 32a...conveyor surface, 33, 34...motor, 35...discharge device, 37...conveyor conveyor, 38...drive pulley, 40...control unit, 41...operation unit, 42...display unit, 43...work position detection unit, 50...imaging processing circuit, 51...imaging control unit, 52...image processing command circuit, 53...image synthesis unit, 54...connection control circuit, 55...area extraction circuit, 56...area connection circuit, 60...inspection processing unit, W... Article, Wa...mouth, Wb...body, MT...movement path, MD...movement direction, #1 to #M...imaging position, WI...article (article in the captured image), D1...imaging interval, ID...imaging direction, S1...detection signal, E1, E2...rotation detection unit, ES1, ES2, ES...rotation detection signal, Trg1...first imaging trigger signal (imaging trigger signal), Trg2...second imaging trigger signal (imaging trigger signal), Trg3...third imaging trigger signal (imaging trigger signal), Tw... Item movement period, Tc...imaging period, Tr...rotation period, Ti...image processing time, TS1...first trigger signal, TS2...second trigger signal, TS3...third trigger signal, FI, FI#1 to FI#M...captured images which are examples of images, RS...reset signal, TA...area, AD...area address, IN...start signal, AI...area image, CI, CI1, CI2...composite image (area connected image), C, C1 to C3...optical axis, θ1...first angle, θ2...second angle.

Claims

1. An object is imaged M times (where M is a natural number equal to or greater than 3) from relatively different directions in a circumferential direction to obtain M images of different parts of the object in the circumferential direction, and N cameras (where N is a natural number satisfying 2≦N<M) are used to share the M images of the object; a detection unit that detects the article at a detection position before the object reaches a first imaging position among M imaging times; an imaging control unit that generates an imaging trigger signal including M trigger pulses that determine imaging timings of a total of M times that the N cameras will capture images based on detection pulses based on detection results from the detection unit, and causes the N cameras to capture images of the article Ki times (i=1, ..., N) (where Ki is a natural number that satisfies 1 <= Ki < M and that satisfies the sum of the N Ki's = M) based on the M trigger pulses; an image synthesis unit that synthesizes, into one, an object region image including at least a part of an object from among a total of M images obtained by performing Ki imaging operations shared by the N cameras, to generate a synthetic image; An article imaging device comprising:

2. 2 . The article imaging device according to claim 1 , wherein the N cameras are fixed at positions where they can image the article, and image the article M times as it moves along a moving path while rotating.

3. The N cameras are spaced apart along the path of travel; The object imaging device of claim 2, wherein M imaging positions set at imaging intervals from position 1 to position M are equally divided into N groups of Ki (i = 1, ..., N) imaging positions, each of which is responsible for imaging the object.

4. The object imaging device of claim 3, wherein the imaging control unit generates N imaging trigger signals, each including M trigger pulses Ki at a timing that allows imaging of M portions of the object positioned at equal intervals around the circumference from the front, and outputs the N imaging trigger signals to the N cameras.

5. Let the N cameras be i-th (i=1, ..., N) in order from the camera that captures the same item for the first time. The object imaging device of claim 2, wherein the imaging control unit generates M of the trigger pulses at a timing when the imaging period required for the i-th camera to capture Ki images partially overlaps with the imaging period required for the adjacent camera in the order to capture Ki images.

6. The N cameras are arranged in a zigzag pattern alternately at predetermined distances on both sides of the moving path, The object imaging device described in claim 5, wherein the imaging control unit generates Ki trigger pulses to be output to the next camera in the sequence for Ki trigger pulses to be output to the i-th camera at a timing that is phase shifted by an adjustment time that is set to a value smaller than the imaging period for timing adjustment due to both cameras capturing images from opposite sides of the movement path.

7. the movement path includes N movement path portions for moving the article along a straight path or a curved path so as to pass through Ki imaging positions at which the N cameras respectively capture images, Each of the N cameras is arranged in such a direction that its optical axis intersects with a virtual line connecting the first imaging position and the Ki-th imaging position at an angle within a tolerance range of ±10° with respect to a right angle; 6. The article imaging device according to claim 5, wherein the angle formed by the optical axes of the N cameras is set to an angle corresponding to 360° / M.

8. An article imaging device according to any one of claims 1 to 7, and an inspection processing unit that inspects the article based on the composite image input from the article imaging device.

9. An object is imaged M times (where M is a natural number of 3 or more) from relatively different directions in a circumferential direction to obtain M images of different parts of the object in the circumferential direction, and N cameras (where N is a natural number satisfying 2≦N<M) are used to capture the M images of the object; A method for imaging an article using an article imaging device including: a detection unit that detects the article at a detection position before the article reaches a first imaging position among M imaging times and outputs a detection pulse, generating an imaging trigger signal including M trigger pulses that determine imaging timings of a total of M imaging times by the N cameras based on the detection pulses; The N cameras capture images of the article Ki times (i=1, ..., N) (where Ki is a natural number that satisfies 1 ≤ Ki < M and the sum of the N Ki's = M) based on the M trigger pulses; generating a composite image by synthesizing, into one, object region images including at least a part of the object, among a total of M images obtained by performing Ki imaging operations shared by the N cameras; A method for imaging an article comprising:

Images