JP6413811B2 - Cylindrical product inspection apparatus and cylindrical product inspection method - Google Patents

Description

  This case relates to a cylindrical product inspection apparatus and a cylindrical product inspection method.

  An inspection method is disclosed in which an appearance inspection is performed by rotating a cylindrical inspection object, photographing the inspection object with a camera, and developing the output of the camera on a plane (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-45678

  However, if an attempt is made to sequentially capture the cylindrical side surface at predetermined time intervals in order to synthesize the cylindrical side surface from the obtained image, the imaging timing may deviate from the target timing due to the load of the control device or the like. In this case, the cylindrical side surface may not be synthesized with high accuracy from the obtained image. As a result, the inspection accuracy is lowered.

  This case is made in view of the said subject, and aims at providing the cylindrical product inspection apparatus and cylindrical product inspection method which can suppress a test | inspection precision fall.

In one aspect, the cylindrical product inspection device includes: an imaging device that sequentially images the side surface of a cylindrical product that rotates about a cylindrical axis; and two continuous images of a plurality of images acquired by the imaging device. A determination unit that determines whether the amount of movement between the two images obtained by comparing the images is equal to or greater than a threshold value, and a predetermined width portion is cut out from each of the plurality of images and the image on the side surface is synthesized And a correction unit that increases a cutout width on the rear side in the rotation direction of the subsequent image of the two images when it is determined that the value is equal to or greater than the threshold value.

In one aspect, the cylindrical product inspection method sequentially images the side surfaces of the cylindrical product while rotating the cylindrical product about the cylindrical axis as a rotation axis, and cuts out a predetermined width portion from each of the obtained plurality of images. In the case of synthesizing the side images, it is determined whether the amount of movement between the two images obtained by comparing two images that are continuous over time is equal to or greater than a threshold value, In such a case, the cutout width on the rear side in the rotation direction of the subsequent image of the two images is increased.

  A decrease in inspection accuracy can be suppressed.

(A) And (b) is a figure which illustrates the test | inspection of a cylindrical product. (A) is a top view of a cylindrical product inspection apparatus, (b) is a side view of a cylindrical product inspection apparatus. (A) is a figure which illustrates the image obtained when there is no back lighting, (b) is a figure which illustrates the image obtained in the state which irradiated the light to the back of a cylindrical product with back lighting. (A) is a block diagram for demonstrating the hardware constitutions of a control apparatus, (b) is a functional block diagram of a control apparatus. It is a figure which illustrates the cutout part. (A)-(c) is a figure for demonstrating the determination by the movement amount determination part. It is a figure illustrated about correction of cutout width. It is an example of the flowchart performed when a cylindrical product inspection apparatus test | inspects a cylindrical product.

  Prior to the description of the examples, an outline of inspection of cylindrical products will be described.

  FIG. 1A and FIG. 1B are diagrams illustrating an inspection of a cylindrical product. For example, in the inspection of a cylindrical product, as illustrated in FIG. 1A, the cylindrical product is imaged with a line camera while the cylindrical product is rotated about the cylindrical axis. An image of the cylindrical side surface can be synthesized by connecting line images obtained by imaging. However, this method requires as many cameras and illuminations as the number of objects to be inspected, which increases capital investment. As a result, it will not meet the cost control needs.

  Therefore, it is conceivable to perform inspection using an area camera or the like. For example, as illustrated in FIG. 1B, an area camera is used to sequentially image areas including the cylindrical side surface while rotating the cylindrical product about the cylindrical axis as a rotation axis, and a predetermined width portion (for example, A method is conceivable in which a top portion having a predetermined width is cut out in a strip shape, and the cut-out strip-like partial images are connected. Even in this case, an image of the cylindrical side surface can be synthesized.

  However, when imaging is performed sequentially using a general-purpose control device such as a PC (personal computer), the shooting timing may deviate from the target timing depending on the load status of the control device. For example, when the load is large, the imaging interval may increase. In this case, a missing pattern or the like occurs in the image cut out in a strip shape, and the joined image is different from the actual pattern on the side surface of the cylinder, and the inspection accuracy may be lowered. Although it is conceivable to use a dedicated image capturing device, it is expensive. In the following embodiments, a cylindrical product inspection apparatus and a cylindrical product inspection method capable of improving inspection accuracy will be described.

  2A and 2B are diagrams illustrating the overall configuration of the cylindrical product inspection apparatus 100 according to the first embodiment. FIG. 2A is a top view of the cylindrical product inspection apparatus 100. FIG. 2B is a side view of the cylindrical product inspection apparatus 100.

  As illustrated in FIG. 2A, the cylindrical product inspection device 100 includes a fixing unit 10, a rotation device 20, a back illumination 30, an imaging illumination 40, an imaging device 50, a control device 60, and the like. Any one bottom surface of the cylindrical product 70 to be inspected is fixed to the fixing portion 10. When a metal product is used as the cylindrical product 70, a magnet or the like can be used as the fixed portion 10. The cylindrical product 70 is not particularly limited as long as it is cylindrical. In the present embodiment, the cylindrical product 70 is a dry battery as an example.

  The rotating device 20 is a motor or the like, and rotates the fixing unit 10 in accordance with an instruction from the control device 60. Thereby, the cylindrical product 70 rotates about the cylindrical axis as a rotation axis. The backlight 30 is disposed on the opposite side of the imaging device 50 with the cylindrical product 70 interposed therebetween, and irradiates the cylindrical product 70 with light. In the present embodiment, the backlight 30 is arranged so that light is irradiated to the back surface (bottom portion of the side surface) of the cylindrical product 70. The imaging illumination 40 is disposed, for example, on the opposite side of the rotating device 20 with the cylindrical product 70 interposed therebetween, and irradiates light onto the imaging range of the imaging device 50 with respect to the cylindrical product 70. In the present embodiment, the imaging illumination 40 is arranged so that light is applied to the top of the side surface of the cylindrical product 70.

  Since the imaging illumination 40 irradiates the top of the side surface of the cylindrical product 70 with light, the imaging device 50 can accurately image the top of the side surface of the cylindrical product 70. Further, since the back illumination 30 irradiates light from the back side of the cylindrical product 70, contrast appears at the boundary between the side surface of the cylindrical product 70 and the background viewed from the imaging device 50. Thereby, the outer shape of the cylindrical product 70 can be easily recognized in the image obtained by the imaging of the imaging device 50. That is, by using the back illumination 30 and the imaging illumination 40, the imaging device 50 can accurately capture the top of the side surface of the cylindrical product 70 while accurately recognizing the outer shape of the cylindrical product 70.

  FIG. 3A is a diagram illustrating an image obtained by imaging by the imaging device 50 when the backlight 30 is not provided. As illustrated in FIG. 3A, if the backlight 30 is not provided, contrast is unlikely to appear at the boundary between the side surface of the cylindrical product 70 and the background. On the other hand, FIG. 3B is a diagram illustrating an image obtained by imaging with the imaging device 50 in a state in which light is applied to the back surface of the cylindrical product 70 with the back illumination 30. As illustrated in FIG. 3B, when the backlight 30 is used, contrast appears at the boundary between the side surface and the background of the cylindrical product 70, so that the outer shape of the cylindrical product 70 can be easily recognized. In FIGS. 3A and 3B, a shaded pattern is added to a portion that appears as a shadow in the image.

  The imaging device 50 is disposed on the opposite side of the backlight unit 30 with the cylindrical product 70 interposed therebetween, and faces the top of the side surface of the cylindrical product 70. The imaging device 50 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) camera, a CCD (Charge Coupled Device) camera, or the like. The imaging device 50 is used as an area camera. In accordance with an instruction from the control device 60, the imaging device 50 sequentially images the side surfaces of the cylindrical product 70 from the top side in time.

  The image obtained by the imaging device 50 is sent to the control device 60. The control device 60 synthesizes a plurality of images obtained by the imaging device 50 and performs an inspection using the obtained synthesized image. FIG. 4A is a block diagram for explaining the hardware configuration of the control device 60. As illustrated in FIG. 4A, the control device 60 includes a CPU 101, a RAM 102, a storage device 103, an interface 104, and the like. Each of these devices is connected by a bus or the like. A CPU (Central Processing Unit) 101 is a central processing unit. The CPU 101 includes one or more cores. A RAM (Random Access Memory) 102 is a volatile memory that temporarily stores programs executed by the CPU 101, data processed by the CPU 101, and the like. The storage device 103 is a nonvolatile storage device. As the storage device 103, for example, a ROM (Read Only Memory), a solid state drive (SSD) such as a flash memory, a hard disk driven by a hard disk drive, or the like can be used.

  FIG. 4B is a functional block diagram of the control device 60. When the CPU 101 executes the program stored in the storage device 103, as illustrated in FIG. 4B, the control device 60 includes the storage unit 61, the cutout unit 62, the movement amount determination unit 63, and the correction unit 64. The combining unit 65, the inspection unit 66, and the like are realized. Note that each unit of the control device 60 may be hardware such as a dedicated circuit.

  The storage unit 61 receives images (frames) sequentially acquired by the imaging device 50 at a predetermined imaging interval (imaging interval determined from the standard frame rate), and sets the number of images corresponding to the entire circumference of the cylindrical product 70 as time data. Associate and save. The number corresponding to the entire circumference of the side surface can be calculated from the rotation speed of the rotating device 20 and the imaging interval of the imaging device 50. In the present embodiment, as an example, 30 images (frame 0 to frame 29) are stored in the storage unit 61.

  The cutout unit 62 cuts out a predetermined width portion from each of the images stored in the storage unit 61 into a strip shape. As illustrated in FIG. 5, since the cylindrical product 70 has a cylindrical shape, it is difficult to make the amount of reflected light uniform. For example, when focusing on any part of the cylindrical side surface, a part where the focus is not achieved due to the height difference of the cylindrical product 70 appears. Therefore, in the present embodiment, the cutout unit 62 cuts out a predetermined width portion near the top of the cylindrical side surface in order to suppress the height difference in the image.

  Since 30 images are stored in the storage unit 61, as illustrated in FIG. 5, the cutout unit 62 is 6 degrees from the top of the side surface of the cylindrical product 70 to the front side in the rotation direction and 6 ° to the rear side in the rotation direction. A region of 12 degrees in total is cut out. The width corresponding to the rotation angle of 12 degrees can be calculated from the rotation angle of the rotation device 20, the resolution of the imaging device 50, and the like. The cutout unit 62 cuts out an image from the image stored in the storage unit 61 along the outer shape of the cylindrical product 70 in addition to the strip-shaped image. This outer shape image is used for determination by the movement amount determination unit 63. In addition, the cutout of the outline image can be performed based on a luminance value or the like.

  The movement amount determination unit 63 determines whether or not the movement amount of the two images obtained by comparing the two images stored in the storage unit 61 with time and continuous is greater than or equal to a threshold value. judge. FIG. 6A to FIG. 6C are diagrams for explaining determination by the movement amount determination unit 63. FIG. 6A is a diagram illustrating an outer shape image of two front and rear frames that are continuous over time. As an example, the left figure of FIG. 6A is the outline image of frame 0, and the right figure is the outline image of frame 1. In this embodiment, the cylindrical product 70 rotates counterclockwise as viewed from the negative pole side (bottom surface side). Further, in order to facilitate the comparison of the overlap between the frame 0 and the frame 1, the characters are shown in white in the frame 1, but the character typefaces are actually the same in the frames 0 and 1.

  The movement amount determination unit 63 uses the outline image of frame 0 as a template image. In this case, as illustrated in FIG. 6A, the movement amount determination unit 63 cuts a predetermined width at the rotation direction side end. The left figure of FIG.6 (b) is the template image after a cut. The predetermined width is cut because there is no comparison target in the outline image of the frame 1. Next, the movement amount determination unit 63 uses the outline image of the frame 1 as a matching target image (matching image), and searches for a position where the similarity between the template image and the matching image is maximized by template matching. Next, as illustrated in FIG. 6C, the movement amount determination unit 63 extracts a value obtained by subtracting the initial position of the template image from the position where the similarity is the maximum in the matching image as the movement amount a.

  Here, the target movement amount b can be represented by b = Δt × A, for example. The coefficient A is a coefficient (pixel / ms) obtained in advance from the resolution of the imaging device 50, the rotation speed of the rotation device 20, and the like. Δt is an imaging interval time (ms) obtained from the standard frame rate. If the movement amount a is larger than the target movement amount b, the imaging timing of the frame 1 is delayed. Therefore, the movement amount determination unit 63 determines whether or not the movement amount a is equal to or greater than a threshold value. As a threshold value in this case, a value larger than the target movement amount b can be used.

  When it is determined that the movement amount a is equal to or larger than the threshold value, the correction unit 64 makes the cutout width by the cutout unit 62 larger than the target cutout width (set value). For example, as illustrated in FIG. 7, the correction unit 64 does not correct the cut-out position on the left side (front side in the rotation direction) from the center of the cylindrical product 70 and is on the right side (back side in the rotation direction) from the center of the cylindrical product 70. The cutout position is corrected to the right side (back side in the rotation direction) by (ab). Thereby, the cut-out width increases from the target movement amount b to the actual movement amount a.

  The synthesizing unit 65 synthesizes the images of the side surfaces of the cylindrical product 70 by joining the images cut out by the cut-out unit 62 to each frame in time series. For example, the synthesis unit 65 synthesizes an image of the entire side surface of the cylindrical product 70. Next, the inspection unit 66 inspects the composite image. For example, the inspection unit 66 collates the composite image with a reference image created in advance, and determines that the inspection of the cylindrical product 70 is acceptable if the similarity between the two is equal to or greater than a threshold value.

  FIG. 8 is an example of a flowchart executed when the cylindrical product inspection apparatus 100 inspects the cylindrical product 70. As illustrated in FIG. 8, the storage unit 61 receives images sequentially acquired by the imaging device 50, and stores the number of images corresponding to the entire circumference of the side surface of the cylindrical product 70 (for example, 30 images) in association with time data. (Step S1). Next, the composition unit 65 secures a composite image region for generating a composite image (step S2). Specifically, the combining unit 65 captures the number of images (frame 0 to frame 29) corresponding to the entire circumference of the side surface of the cylindrical product 70 and the imaging device per rotation time of the rotation device 20. Multiply by the number of pixels at 50.

  Next, the cutout unit 62 calculates a target cutout position (set value) in each image stored in the storage unit 61 (step S3). Next, the movement amount determination unit 63 determines whether or not processing for a predetermined number (the number corresponding to the entire circumference of the side surface of the cylindrical product 70) has been completed (step S4). By executing step S4, it is possible to determine whether the image clipping has been completed.

  When it is determined “No” in step S4, the movement amount determination unit 63 determines the template image obtained from the outline image of the previous frame (for example, frame 0) and the next frame (for example, frame 1). A matching process with the external shape image (matching image) is performed. Thereby, the movement amount of frame 1 from frame 0 is extracted (step S5). Next, the movement amount determination unit 63 determines whether or not the movement amount extracted in step S5 is greater than or equal to a threshold value (step S6). As a threshold value in this case, a value larger than the target movement amount, such as a predetermined multiple of the target movement amount, can be used. For frame 0, since the previous frame does not exist, the movement amount is less than the threshold value.

  When it is determined “No” in step S6, the correction unit 64 does not correct the cutout width. Thereby, the cutout unit 62 cuts out the portion of the target cutout width at the target cutout position in the frame 1 (step S7). When it is determined as “Yes” in step S <b> 6, the correction unit 64 performs correction to increase the cut-out width. Accordingly, the cutout unit 62 cuts out a portion having a width wider than the target cutout width in the frame 1 (step S8). After execution of step S7 or step S8, the compositing unit 65 pastes the cut-out part (strip) into the composite image area (step S9). Thereafter, the process is executed again from step S4. In this case, the matching process is performed using the next two frames over time from the previous time. In step S9, cutout portions that are continuous with time are sequentially pasted.

  If “Yes” is determined in step S4, the synthesizing unit 65 completes the synthesized image (step S10). Next, the inspection unit 66 compares the composite image with the reference image (step S11). For example, the inspection unit 66 calculates the similarity between both images. Next, the inspection unit 66 determines whether or not there is a difference between the two (step S12). For example, it is determined whether the similarity between both images is equal to or less than a threshold value. When it is determined as “Yes” in Step S <b> 12, the inspection unit 66 determines that the inspection has failed. When it is determined as “No” in Step S12, the inspection unit 66 determines that the inspection is passed.

  According to this embodiment, when the amount of movement between two images that are continuous over time is equal to or greater than a threshold value, the cutout width of the subsequent image of the two images increases, so that the cylindrical product The omission of the side surface of the is suppressed. Thereby, even if the imaging timing of the imaging device 50 is shifted due to the load of the control device 60 or the like, a decrease in the inspection accuracy of the cylindrical product is suppressed.

  Further, since the back illumination 30 irradiates light to the cylindrical product 70 from the opposite side of the imaging device 50 with the cylindrical product 70 interposed therebetween, it becomes easy to cut out the outer shape of the cylindrical product 70 in the image acquired by the imaging device 50. Thereby, the determination accuracy of the movement amount between two images that are continuous with time is improved. Furthermore, since the imaging illumination 40 irradiates light to the imaging range of the imaging device 50, the imaging accuracy of the cylindrical product 70 by the imaging device 50 is improved. In addition, when calculating the similarity between two images that are continuous over time, the predetermined width at the rotation direction side end of the cylindrical product 70 is cut in the previous image, so that the calculation accuracy of the similarity is high. improves.

  In the above-described embodiment, the imaging device 50 images one cylindrical product 70, but a plurality of cylindrical products 70 that rotate in synchronization may be imaged simultaneously. In this case, since the number of the imaging devices 50 can be suppressed, the cost can be reduced.

  In the above embodiment, when the movement amount between two images that are continuous over time is equal to or larger than the threshold value, an image having a width corresponding to the movement amount is cut out, but is larger than the set value. An image having a width may be cut out. Even in this case, the lack of the cylindrical side surface in the composite image is suppressed.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Fixing part 20 Rotating device 30 Back surface illumination 40 Imaging illumination 50 Imaging apparatus 60 Control apparatus 61 Storage part 62 Cutout part 63 Movement amount determination part 64 Correction part 65 Composition part 66 Inspection part 70 Cylindrical product 100 Cylindrical product inspection apparatus

Claims (4)

An imaging device that sequentially images the side surfaces of a cylindrical product that rotates about a cylindrical axis;
A determination unit that determines whether or not a movement amount between the two images obtained by comparing two images that are continuous over time among the plurality of images acquired by the imaging device is equal to or greater than a threshold;
A combining unit that cuts out a predetermined width portion from each of the plurality of images and combines the side images;
A cylindrical product inspection device comprising: a correction unit that increases a cut-out width on the rear side in the rotation direction of the subsequent image of the two images when it is determined that the threshold value is equal to or greater than the threshold value. .   The cylindrical product inspection apparatus according to claim 1, further comprising an illumination that irradiates the cylindrical product with light from a side opposite to the imaging device with the cylindrical product interposed therebetween.   3. The cylindrical product according to claim 1, wherein the determination unit compares the two images after cutting a predetermined width at a front side end in a rotation direction in a previous image. 4. Inspection device. While rotating the cylindrical product about the cylindrical axis as a rotation axis, sequentially image the side surface of the cylindrical product,
When a predetermined width portion is cut out from each of a plurality of obtained images and the side image is synthesized, movement between the two images obtained by comparing two images that are continuous over time It is determined whether the amount is equal to or greater than a threshold value, and when the amount is equal to or greater than the threshold value, a cutout width on the rear side in the rotation direction of the subsequent image of the two images is increased. Product inspection method.

Images