JP2007003243A - Visual examination device of long article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual examination device of a long article capable of suppressing the load and time required in image processing by preventing overlapping image processing while photographing the image of the long article without exception even if the feed speed of the long article is made variable. <P>SOLUTION: The visual examination device of the long article is equipped with an imaging means 4 for photographing the long article 2 at a definite time interval, a distance measuring means 8 for detecting the travel distance of the long article 2 and an image processing means 6. The image processing means 6 is constituted so that the travel distance of the long article moved from the start of the photographing of the image subjected to image processing of the long article to the start of the next photographing is calculated on the basis of the detection result from the distance measuring means 8 and this moving distance region is specified as an image processing region to perform image processing in the image processing region. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an appearance inspection apparatus for a long object that inspects a surface defect of a continuously conveyed long object by image processing.

  As an inspection device for detecting defects on the surface of a long object, for example, while conveying the long object at a constant speed, the surface of the long object is imaged using a two-dimensional camera, and the obtained image is One that detects an abnormal portion by performing binarization processing or the like is known (for example, shown in Patent Document 1).

  In the inspection apparatus shown in Patent Literature 1, the field of view size of a two-dimensional camera is an imageable area, and image processing is performed using this imageable area as one image frame. In Patent Document 1, the timing of opening the shutter of the camera is performed at equal intervals so that the image frame always has a constant size.

  In addition, in the inspection apparatus shown in Patent Document 1, in order to obtain and inspect and capture the images captured by the camera for a continuously conveyed long object without omission, the image to be captured is predetermined in the traveling direction of the long object. An overlap portion is provided.

JP 2001-124702

  In the inspection apparatus shown in Patent Document 1, since a long object is controlled to be conveyed at a constant speed, the image frame is always constant by controlling the shutter opening operation of the camera at equal intervals. It becomes the size of.

  However, in the case of slowing down the conveyance speed of a long object, the apparatus of Patent Document 1 performs the shutter opening operation of the camera at equal intervals, so that it overlaps in adjacent image frames. The part that is being imaged will occur.

  Then, if image processing is performed for each image frame, a portion that has been imaged redundantly will be inspected redundantly. As a result, a wasteful operation in which an abnormal portion of a long object is detected in an overlapping manner is performed, and the load on the calculation process increases.

  In addition, as a method of imaging so that there is no overlapping imaged portion in the image frame regardless of the conveying speed of the long object, for example, the camera is used when the long object exceeds the set movement amount. In other words, imaging is performed by a so-called random shutter system that generates an imaging command.

  The random shutter method is a method in which an imaging trigger of the camera is given by an external trigger. In this case, as shown in FIG. 11, an external trigger is given to the camera drive control unit A, and the camera drive control unit A receives a signal from the distance measuring means C provided in the transport device that transports the long object B. The camera drive control unit A obtains the movement amount of the long object B based on this signal, and controls the opening operation of the shutter of the camera D so that the movement interval is constant. An image captured by the camera D is sent to the image processing device F for each image frame E. In addition, the graph in FIG. 11 shows the relationship between time t and the conveyance speed v, and the arrow has shown the imaging timing.

  However, in the case of the random shutter method, the image capturing timing of the camera is controlled so as to open the shutter of the two-dimensional camera after the movement amount of the long object is obtained by an external trigger. The imaging timing is delayed by the refresh time, and a long object cannot be captured without omission.

  Furthermore, since the start of scanning of the image receiving element inside the camera is synchronized with the clock inside the camera and exposure preparation is performed after the trigger is generated, the imaging timing is also delayed in this respect.

  As a result, in order to capture an image of a long object without omission, it is necessary to reduce the conveying speed of the elongate object to a speed at which an image can be captured without omission even if the imaging timing is delayed.

  As described above, in the random shutter method, since the opening operation of the shutter of the two-dimensional camera is performed after obtaining the moving amount of the long object, a large load is applied to the image processing.

  Moreover, in the inspection apparatus of patent document 1, as shown in FIG. 12, the overlap part F is provided in order to inspect a long object completely without omission. As described above, in the case where the overlap portion F is included, it is necessary to collate the abnormal portion detected in the overlap portion F of the adjacent image frame E to check the overlap of the abnormal portion. In this case, when collation of the abnormal part detected in the overlap part F is performed based on each image after the image processing is performed, the process for determining overlap requires a load and time.

  Therefore, the present invention is capable of capturing images without omission even if the conveyance speed is variable for a long object, and avoiding redundant image processing, and reducing the load required for image processing. The main object is to provide an appearance inspection apparatus for long objects capable of suppressing time. As another object, when there are overlapping portions in the captured image, it is possible to reduce the load and time required for the process of determining the duplication of abnormal portions.

  In the present invention, a long object is continuously conveyed in the length direction by the conveying means, and the long object is imaged for each predetermined imageable area by the imaging means, and the captured image is processed by the image processing means. In the appearance inspection apparatus for long objects, the above problem is solved.

  The long object visual inspection apparatus according to the present invention includes a distance measuring unit for detecting a moving distance of the long object conveyed by the conveying unit, and the imaging unit captures images at a constant time interval. .

  Examples of the imaging means include a two-dimensional camera such as a CCD camera. The imaging means obtains a two-dimensional image using the field size as the imageable area. This two-dimensional image is sent to the image processing means. For example, the image pickup means controls to take an image of a long object at a constant time interval by a camera drive control unit built in the camera.

  Further, when an image is picked up by the image pickup means, the long object is irradiated with light. Therefore, an illuminating device is arrange | positioned so that the imaging area of an imaging means may be illuminated. For example, when the long object is transparent, the illuminating device arranges the imaging device above the long object and arranges the illuminating device coaxially with the imaging device below. When the long object is opaque, an imaging device and an illumination device are arranged above the long object. At this time, coaxial ring illumination or coaxial epi-illumination can be used as the illumination device.

  The detection result of the distance measuring means is sent to the image processing means. An example of the distance measuring means is a rotary encoder. When a rotary encoder is used, the rotation angle of the transport roller used for the transport means is detected. The moving distance of the long object can be detected based on the rotation angle and the conveyance amount per rotation of the conveyance roller. The distance measuring unit continues to detect the moving distance of the long object while the long object is moving regardless of the imaging timing of the imaging unit.

  Based on the detection result from the distance measuring means, the image processing means calculates the moving distance of the long object that has moved from the start of the imaging of the image to be processed to the start of the next imaging. The distance is specified as an image processing area in one imageable area, and image processing is performed in this image processing area.

  When a two-dimensional image is captured by the imaging device, the image captured by one imaging is an imageable area. When the length in the transport direction in the imageable area is the moving distance of the long object that has been moved from the start of the imaging of the image to the start of the next imaging, the imageable area is used for image processing. It becomes an area. However, when the transport speed of a long object is variable, specifically, when the transport speed becomes slow, the next image acquired in the next newly acquired image (overlapping in the transport direction) Part) may be included.

  Therefore, in the present invention, the image processing means does not perform image processing by overlapping the overlapped area. That is, the moving amount of the long object obtained from the distance measuring means is converted into a pixel unit for the captured image, and only the amount actually moved from the acquired two-dimensional image (imageable area) is subjected to image processing. Specify as an area. By specifying the image processing area in this way, it is possible to prevent the useless operation that the abnormal part is detected by being duplicated because it is not necessary to inspect the already processed part. The load on the calculation process can be optimized.

  By the way, when an abnormal part is detected, when the abnormal part is mechanically marked or removed while conveying a long object, when performing marking or removal work, Gradually lower the transport speed and increase the speed to the specified speed again after the work.

  Even in such a case, as in the present invention, by specifying the image processing region based on the actual moving distance of the long object, it is possible to flexibly follow the change in speed without causing an inspection omission, An image processing area can be obtained reliably.

  Furthermore, the image processing means has a first image memory and a second image memory for storing an image picked up by the image pickup means, and the image picked up by the image pickup means is stored in the first image memory and the second image memory. It is preferable to store alternately.

  In this case, the image processing means stores the image in the other image memory that is captured immediately before the image being captured while the long object is captured to store the image in one image memory. Process the images that are being processed. In addition, before writing to the image memory of the captured image is completed, the image is always read out from the image memory, and processing such as binarization processing and abnormal portion determination is completed. Control writing of images.

  As described above, since the processing of the previously captured image is started simultaneously with the start of the image capturing, the image processing is not performed during the imaging preparation time and the imaging time as in the conventional random shutter method. Therefore, the time from the application of the imaging trigger to the end of the image processing can be shortened.

  Further, in the image processing means of the present invention, in order to inspect a long object without omission by using the image captured by the imaging means, each image processing area is overlapped at both ends in the conveyance direction of the long object. It is preferable to set an image processing area in

  As described above, when the overlap portion is set, if there is an abnormal portion in the overlap portion, an abnormal portion overlapping two adjacent images is imaged. The position data of these abnormal portions can be calculated from the position data for the long object by the distance measuring means and the position data in the image processing area of the image.

  Therefore, when setting the overlap portion, the image processing means includes a first NG information result buffer and a second NG information result buffer for storing the abnormal portion detected at the rear end portion in the conveyance direction in the image processing area. To have.

  Abnormal parts detected at the trailing edge of the image stored in the first image memory are detected at the trailing edge of the image stored in the second image memory in the first NG information result buffer. The abnormal part is stored in the second NG information result buffer.

  Then, the image processing means collates the abnormal part detected at the front end in the transport direction with respect to the image being processed, and compares the abnormal part detected at the rear end in the transport direction with respect to the previous image. The difference in position data is calculated. The data of the abnormal part detected at the rear end in the transport direction in the previous image is acquired from the first NG information result buffer or the second NG information result buffer. When the difference in the position of the abnormal part is equal to or less than a preset threshold value, it is determined that these abnormal parts are the same.

  If it is determined that the abnormal part is the same, for the image on the rear side in the transport direction, the abnormal part detected at the front end in the transport direction of the image processing area during the image processing is the detected abnormal part. To avoid counting. By processing in this way, the abnormal part at the front end is not stored in, for example, the NG total result buffer provided in the image processing unit, and the detection result of the abnormal part is prevented from being stored redundantly. .

  And when it has a judgment means which judges the defect of the surface of a long object based on the image data processed by the image processing means, it sends image data including the abnormal part detected by the image processing means to the judgment means To. The determination means is constituted by a computer, for example. The determining means determines that there is a defect inside if the surface or material of the long object is transparent when there is an abnormal part in the image data obtained from the image processing means.

  In the long object visual inspection apparatus of the present invention, the image processing area to be inspected is specified based on the movement amount measurement by the distance measuring means in the captured imageable area. There is no inspection. As a result, it is possible to prevent a useless operation in which an abnormal part is detected by being duplicated, and it is possible to suppress a load on calculation processing.

  Furthermore, in the case of the double buffering method using the first image memory and the second image memory, since the processing of the previously captured image can be started simultaneously with the start of the image capturing, there is no measurement omission. In addition, it is possible to perform image processing with a short time from the application of the imaging trigger to the end of image processing. As a result, even if the conveying speed of the long object is fast, the long object can be reliably imaged without omission.

  Further, in the present invention, when an image processing area including an overlap portion is specified from a captured image, an abnormality detected at the rear end in the transport direction when detecting an abnormal portion in the image processing area The position data of the part is stored in the NG information result buffer corresponding to the image memory in which each image is stored.

  When an abnormal portion is detected at the front end in the transport direction during image processing, the rear end in the transport direction stored in the NG information result buffer in which the abnormal portion at the front end is detected in the previous image. It matches with the abnormal part of the part. If the positions of the respective abnormal portions overlap, it is determined that they are the same abnormal portion, and the abnormal portion at the front end of the image being processed is not counted as an abnormal portion.

  As described above, during the image processing, the duplication of the abnormal part in the overlap part at the front end part in the transport direction is determined. Therefore, when the detection result of the abnormal part is stored in the final NG comprehensive result buffer, The abnormal part detected by the part is not stored as an abnormal part. As a result, it is possible to eliminate redundant storage of abnormal portions and to perform high-speed image processing.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a long object visual inspection apparatus according to the present invention will be described below with reference to the drawings. As shown in the schematic configuration diagram of FIG. 1, the appearance inspection apparatus 1 of the present embodiment includes a conveying means 3 for continuously conveying a long object 2 to be inspected, a CCD camera (imaging means) 4, and an illumination device 5. And image processing means 6 and determination means 7. In the present embodiment, the long object 2 whose appearance is to be inspected is a resin sheet made of a transparent material.

  The transport unit 3 has a pair of transport rollers 31, and a distance measuring unit 8 is attached to the transport rollers 31. A rotary encoder is used as the distance measuring means 8. The encoder 8 detects the rotation speed and rotation angle of the transport roller 31. The detection result detected by the encoder 8 is input to the counter unit 61 of the image processing means 6. The encoder 8 continues to detect the moving distance of the long object 2 while the long object 2 is moving, regardless of the imaging timing of the CCD camera 4, and the detection result is input to the counter unit 61. .

  The CCD camera 4 and the illumination device 5 are arranged so as to be coaxial, the CCD camera 4 is arranged above the long object 2, and the illumination device 5 is arranged below the long object 2.

  FIG. 2 shows the internal configuration of the image processing means 6. The image processing means 6 includes an image capturing unit 62 having a first image memory 62a and a second image memory 62b, a counter unit 61 to which a detection result from the encoder 8 is input, an NG total result buffer 63, a first NG information result A buffer 64, a second NG information result buffer 65, a memory 66, and an I / F unit (interface unit) 67 are provided.

  The image picked up by the CCD camera 4 is a two-dimensional image with the field of view size of the camera as an imageable region. In this embodiment, as shown in FIGS. 3 and 4, a two-dimensional image of the imageable area is used as an image frame 21, and the surface of the long object 2 is conveyed for each image frame 21 while conveying the long object 2. Images are taken continuously.

  FIG. 3 shows a graph showing the relationship between the time t and the conveyance speed v, and a position at which imaging on the long object 2 is started corresponding to the imaging timing indicated by the arrow in the graph. FIG. 4 shows a state of the image frame 21 in which a long object having a linear flaw is sequentially imaged at regular time intervals.

  The CCD camera 4 and the illuminating device 5 are driven and controlled by a command from a camera drive control unit (not shown in FIGS. 1 and 2). The CCD camera 4 and the illuminating device 5 operate in synchronization with an imaging command from the camera drive control unit, and perform imaging while illuminating the long object 2 with the illuminating device 5. In the present embodiment, the timing of imaging by the CCD camera 4 is controlled so as to be a constant time interval, as shown in the graph of FIG. In this embodiment, a 30 Hz CCD camera 4 is used and imaging is performed every 33.3 msec.

  In the present embodiment, the image signal from the CCD camera 4 is not shown, but after being A / D converted by the A / D converter, the first image memory 62a of the image capturing unit 62 or the second image memory 62a Input to the image memory 62b. As shown in FIG. 5, the image data of the image frame 21 captured by the CCD camera 4 is alternately stored in the first image memory 62a and the second image memory 62b every time it is captured. ing.

  Then, as shown in FIG. 5, the image processing means 6 is stored in the other image memory while the long object 2 is being imaged in order to store the image in one image memory, and the image being imaged. The image captured immediately before is processed. In this embodiment, before writing of the captured image to the image memory is completed, that is, before 33.3 msec elapses, the image is always read out from the image memory, and binarization processing, determination of an abnormal part, etc. The operation of the image processing and the image writing to the image memory is controlled so that the above process ends.

  The image processing performed by the image processing means 6 is based on the detection result from the encoder 8 stored in the counter unit 61, and from the start of imaging for the image to be processed from now until the next imaging is started. The moving distance of the long object 2 moved to is calculated. Then, as shown in FIG. 4, this moving distance is specified as an image processing area 22 in a single imageable area (image frame 21), and image processing such as binarization processing is performed in this image processing area 22. I do. In FIG. 4, an image processing area 22 indicates a cross-hatched portion, and an arrow corresponding to the left end of each image frame 21 indicates an imaging start position. Further, FIG. 4 shows an imaging state when the conveyance speed of the long object 2 is gradually increased. In FIG. 4, since the conveyance speed is gradually increased, the area of the image processing region 22 of each image frame 21 is gradually increased.

  Specifically, the image processing area 22 is specified by converting the moving amount of the long object obtained by the encoder 8 into the pixel unit with respect to the image frame 21 captured by the CCD camera 4, and obtaining the acquired image frame 21. Only the amount actually moved is specified as the image processing area 22.

  Furthermore, in this embodiment, in order to inspect the long object 2 without omission by the image data captured by the CCD camera 4 in the image processing means 6, as shown in FIG. The image processing areas 22 are set so as to overlap at both ends of the long object 2 in the conveyance direction. For example, when the conveyance direction length of the imageable area of one image frame 21 is 18 mm and the specified conveyance speed of the long object 2 is 30 m / min, the overlap portion 23 is per image frame at that time. Since the moving amount of the long object 2 is 16.6 mm, the length of the overlap portion 23 on one side is set to 0.7 mm.

  As described above, when the overlap portion 23 is set, the image processing means 6 uses the first NG information result buffer 64 or the second NG as the abnormal portion detected at the rear end portion in the transport direction in the image processing area 22. The information is stored in the information result buffer 65.

  At this time, the abnormal portion of the image frame 21 stored in the first image memory 62a is stored in the first NG information result buffer 64, and the abnormal portion of the image frame 21 stored in the second image memory 62b is stored in the second NG information. Store in the result buffer 65.

  Then, the image processing means 6 compares the abnormal part detected at the front end in the transport direction with respect to the image under image processing with the abnormal part detected at the rear end in the transport direction in the previous image, When the difference in the position of the abnormal part is equal to or less than a preset threshold value, it is determined that they are the same. The data of the abnormal part detected at the rear end in the transport direction in the previous image is acquired from the first NG information result buffer 64 or the second NG information result buffer 65 in which this data is stored.

  As described above, the position data of the abnormal part detected in the overlap part 23 of each image frame 21 is calculated from the position data for the long object by the encoder 8 and the position data in the image processing area 22 of the image.

  Therefore, when there is an abnormal portion in the overlap portion 23, the data of the abnormal portion detected at the rear end portion in the long object conveyance direction in the image processing area 22 in the previous image is stored in the first NG information result buffer. 64 or second NG information result buffer 65. Then, the extracted abnormal portion is collated with the abnormal portion detected at the front end in the transport direction in the image processing area of the image acquired next. A difference in position data of each abnormal part is calculated, and if this difference is equal to or less than a preset threshold value, it is determined that the abnormal parts are regarded as the same abnormal part.

  Then, the image on the rear side in the transport direction is processed so that the abnormal portion detected at the front end in the transport direction of the image processing area 22 is not counted as a detected abnormal portion during image processing. The abnormal portion at the front end that is not counted is not stored in the NG total result buffer 63 provided in the image processing means 6. As described above, in the NG total result buffer 63, the abnormal part detected in the overlap part 23 is not redundantly stored in the detection result.

  In the image processing means 6, according to the image processing program 68, the above-described image processing for detecting the abnormal portion, the detected abnormal portion is stored in the NG total result buffer 63, or at the rear end in the transport direction in the image. An operation of storing the detected abnormal portion in the first NG information result buffer 64 or the second NG information result buffer 65, an operation of extracting data from the counter unit 61, and the like are performed via the bidirectional bus 69. The memory 66 is used for executing the image processing program 68.

  Then, the image data including the abnormal part stored in the NG total result buffer 63 is transferred from the I / F unit 67 to the determination means 7. Based on the image data in the NG total result buffer 63, the determination means 7 determines that there is a defect at a predetermined position on the surface or inside of the long object 2 when there is an abnormal portion in the image processing area 22. . The determination means 7 is constituted by a computer.

  Next, a method for controlling image processing of the image processing means 6 in the appearance inspection apparatus according to the present embodiment will be specifically described. 6 to 10 are flowcharts showing a procedure of image processing control in the image processing means 6 according to this embodiment.

  In the present embodiment, image processing of the image frame 21 stored in the second image memory 62b is performed while writing an image in the first image memory 62a. Next, after completing the writing of the image to the first image memory 62a, the image processing of the image frame 21 stored in the first image memory 62a is performed while writing the image to the second image memory 62b. . These image writing and image processing operations are repeated until the remaining inspection area of the long object 2 becomes equal to or less than one image frame.

  First, in order to write an image in the first image memory 62a, imaging by the CCD camera 4 is started (step S1). At this time, the time when the imaging is started (counter storage A) is stored in the counter unit 61 (step S2). The counter storage A is set based on the detection result input from the encoder 8 to the counter unit 61.

  While performing an operation of writing an image to the first image memory 62a (step S3), an image captured immediately before the image currently being written is processed (step S4). The image processing performed in step S4 is performed on the image data stored in the second image memory 62b. Detailed control of the image processing in step S4 will be described later.

  When the image processing of the image data stored in the second image memory 62b is completed, the image writing to the first image memory 62a is completed (step S5).

  Next, in order to write an image in the second image memory 62b, imaging by the CCD camera 4 is started (step S6). At this time, the time when the imaging is started (counter storage B) is stored in the counter unit 61 (step S7). Also in this case, the counter storage B is set based on the detection result input from the encoder 8 to the counter unit 61.

  While performing the operation of writing the image to the second image memory 62b (step S8), the image captured immediately before the image currently being written, that is, the first image memory 62a in step S3 described above. The written image is processed (step S9). Detailed control of the image processing in step S9 will also be described later.

  When the image processing of the image data stored in the first image memory 62a is completed, the writing of the image to the second image memory 62b is completed (step S10).

  Next, it is determined whether or not to stop the imaging of the long object 2 to be inspected (step S11). When the number of image frames 21 to be captured is equal to or less than the remaining one image frame, the imaging is stopped, and the imaging and image processing are ended. If there are two or more remaining image frames 21 that can be captured, the process returns to step S1, and steps S1 to S11 are repeated.

  The control of the image processing of the second image memory 62b in step S4 will be described in detail below based on FIG. 7 and FIG.

  The counter storage A (imaging start time) of the image frame 21 currently written in the first image memory 62a is extracted from the counter unit 61 (step S41). Further, the counter storage B (imaging start time) for the image frame 21 stored in the second image memory 62b from which image processing is to be performed is extracted from the counter unit 61 (step S42).

  Time from the start of imaging of the image frame 21 stored in the second image memory 62b to the imaging of the next image frame 21 (the image frame currently being captured) is calculated by subtracting the counter memory A from the counter memory B Is calculated (step S43). Based on the calculated time and the detection result from the encoder 8, the distance the long object 2 has actually moved within the calculated time is obtained (step S44). From this moving distance, the part of the distance that the long object 2 has actually moved is obtained from the image captured in the image frame 21 (the image stored in the second image memory 62b) to be subjected to image processing. be able to. The moving distance in the image frame 21 is replaced with the number of pixels.

  Furthermore, since the overlap portion 23 is set in each image frame 21, the overlap portion 23 on the rear side in the transport direction is replaced with the number of images. Then, the image processing area 22 is calculated by adding the rear overlap portion 23 and the moving distance (step S45).

  Next, only the portion of the image processing area 22 in the image frame 21 is binarized (step S46). The binarization process is performed, for example, by taking a threshold value such that a normal part of the long object 2 having no foreign matter or scratches is white and a part having the foreign matter is black. Then, the size of the black part is specified (step S47). The specification of the size or the like of the black portion is not only the size of the black portion but also the length and the position of the center of gravity. Further, when there are a plurality of black portions in the image processing area 22, the size of each black portion is specified.

  Once the size of the black part can be identified, a threshold value is set as a reference for determining whether the black part is an abnormal part or a scratch within the range of the normal part. Is greater than this threshold value (step S48). Also in this determination, when there are a plurality of black portions in the image processing region 22, the size of each black portion is determined.

  If the size of all black portions is equal to or smaller than this threshold, it is determined that there is no abnormal portion in the image processing area 22 (step S49), and the image processing control for this image frame is terminated.

  If there is at least one black part larger than the threshold, it is determined that there is an abnormal part in the image processing area 22 (step S50).

  The positions in the image processing area 22 are calculated for all black portions determined to be abnormal (step S51) (see FIG. 8).

  Next, it is determined whether or not the abnormal part is at the rear end in the transport direction in the image processing area 22 (step S52). If there is an abnormal part at the rear end in the transport direction, the position of the abnormal part is stored in the second NG information result buffer 65 (step S53).

  If there is no abnormal portion at the rear end portion in the transport direction, or after the storage in the second NG information result buffer 65 in step S53, is the abnormal portion at the front end portion in the transport direction in the image processing area 22? It is determined whether or not (step S54).

  If there is an abnormal part at the front end in the transport direction, the position data of the abnormal part existing at the rear end in the transport direction for the image frame 21 captured immediately before is extracted from the first NG information result buffer 64 ( Step S55). Then, the position data of the abnormal portion stored in the first NG information result buffer 64 is collated with the position data of the abnormal portion existing at the front end in the transport direction for the image frame 21 currently being processed (step). S56).

  A difference (collation data) between the position data of each abnormal portion is calculated, and it is determined whether or not this difference is equal to or less than a preset threshold value (step S57).

  If the difference in position data is less than or equal to a preset threshold value, it is determined that they are the same abnormal part, and the abnormal part detected at the front end in the transport direction of the image processing area 22 during image processing has already been detected. Is processed so as not to be counted as an abnormal part (step S58).

  If the difference between the position data is larger than a preset threshold value, it is determined that the difference is regarded as a different abnormal portion. The abnormal portion detected at the front end in the conveyance direction of the image processing area 22 during image processing is an abnormal portion. (Step S59).

  Then, after the count processing in step S58 and step S59, the abnormal part detection result is stored in the NG total result buffer 63 (step S60).

  Even when it is determined in step S54 whether or not the abnormal part is present at the front end in the transport direction in the image processing area 22, it is determined that the abnormal part is not present at the front end in the transport direction. It memorize | stores in 63 (step S60).

  The abnormal part data stored in the NG total result buffer 63 is output to the determination means 7 via the I / F unit 67 (step S61).

  In the determination means 7, as described above, if there is an abnormal portion in the image processing area 22 based on the image data in the NG total result buffer 63, the surface of the long object 2 or a predetermined position on the inside thereof is defective. Judge that there is.

  Further, the control of the image processing of the first image memory 62a in step S9 will be described in detail below based on FIG. 9 and FIG. The basic control is the same as the control in step S4 described above.

  The counter storage B (imaging start time) of the image frame 21 currently written in the second image memory 62b is extracted from the counter unit 61 (step S91). Further, the counter storage A (imaging start time) for the image frame 21 stored in the first image memory 62a to be subjected to image processing is extracted from the counter unit 61 (step S92).

  Time from the start of imaging of the image frame 21 stored in the first image memory 62a to the imaging of the next image frame 21 (the image frame currently being captured) is calculated by subtracting the counter memory B from the counter memory A Is calculated (step S93). Based on the calculated time and the detection result from the encoder 8, the distance that the long object 2 has actually moved within the calculated time is obtained (step S94). From this moving distance, the portion of the distance that the long object 2 has actually moved is obtained from the image captured in the image frame 21 (the image stored in the first image memory 62a) to be subjected to image processing. be able to. The moving distance in the image frame 21 is replaced with the number of pixels.

  Further, the overlap portion 23 on the rear side in the transport direction is replaced with the number of images. Then, the image processing region 22 is calculated by adding the rear overlap portion 23 and the moving distance (step S95).

  Next, binarization processing is performed only on the portion of the image processing area 22 in the image frame 21 (step S96). Then, the size or the like of the black part is specified (step S97).

  If the size or the like of the black portion can be specified, it is determined whether the size of the black portion is larger than this threshold (step S98).

  If the size of all black portions is less than or equal to this threshold value, it is determined that there is no abnormal portion in the image processing area 22 (step S99), and the image processing control for this image frame is terminated.

  If there is at least one black part larger than the threshold, it is determined that there is an abnormal part in the image processing area 22 (step S100).

  The positions in the image processing area 22 are calculated for all black portions determined to be abnormal (step S101) (see FIG. 10).

  Next, it is determined whether or not the abnormal part is at the rear end in the transport direction in the image processing area 22 (step S102). If there is an abnormal part at the rear end in the transport direction, the position of the abnormal part is stored in the first NG information result buffer 64 (step S103).

  If there is no abnormal part at the rear end in the transport direction, or after the storage in the first NG information result buffer 64 in step S103, is the abnormal part at the front end in the transport direction in the image processing area 22? It is determined whether or not (step S104).

  If there is an abnormal part at the front end in the transport direction, the position data of the abnormal part existing at the rear end in the transport direction for the image frame 21 captured immediately before is extracted from the second NG information result buffer 65 (step S105). Then, the position data of the abnormal portion stored in the second NG information result buffer 65 is collated with the position data of the abnormal portion existing at the front end in the transport direction for the image frame 21 currently being processed (step). S106).

  A difference (collation data) between position data of each abnormal part is calculated, and it is determined whether or not the difference is equal to or less than a preset threshold value (step S107).

  If the difference in position data is less than or equal to a preset threshold value, it is determined that they are the same abnormal part, and the abnormal part detected at the front end in the transport direction of the image processing area 22 during image processing has already been detected. Is processed so as not to be counted as an abnormal part (step S108).

  If the difference between the position data is larger than a preset threshold value, it is determined that the difference is regarded as a different abnormal portion. The abnormal portion detected at the front end in the conveyance direction of the image processing area 22 during image processing is an abnormal portion. (Step S109).

  Then, after the count processing in step S108 and step S109, the abnormal part detection result is stored in the NG total result buffer 63 (step S110).

  In the determination of whether or not the abnormal part in step S104 is at the front end in the transport direction in the image processing area 22, even if it is determined that there is no abnormal part at the front end in the transport direction, the detection result of the abnormal part is stored in the NG total result buffer It memorize | stores in 63 (step S110).

  The abnormal part data stored in the NG total result buffer 63 is output to the determination means 7 via the I / F unit 67 (step S101).

  As described above, in the long object visual inspection apparatus according to the present embodiment, the image processing region 22 to be inspected in the image frame 21 is specified based on the movement amount measurement result by the encoder 8, and thus overlap. Except for the portion 23, the already image-processed portion is not redundantly inspected. As a result, it is possible to prevent a useless operation in which an abnormal part is detected by being duplicated, and it is possible to suppress a load on calculation processing.

  Further, image data is alternately stored in the first image memory 62a and the second image memory 62b, and the image data stored in the other image memory is processed while the image is being written in one image memory. Therefore, the processing of the previously captured image can be started simultaneously with the start of the image capturing. As a result, it is possible to perform image processing without measurement omission and in a short time from when the imaging trigger is given until the image processing is completed. As a result, even if the conveying speed of the long object is fast, the long object can be reliably imaged without omission.

  In the present embodiment, the overlap portion 23 is provided in the image processing area 22 of the image frame 21, but the position data of the abnormal portion detected at the rear end in the transport direction during image processing is next imaged. The position data of the abnormal part detected at the front end in the transport direction of the image processing area 22 in the image frame 21 to be checked is collated to determine whether or not these abnormal parts are the same. If the same abnormal part is determined, the abnormal part at the front end in the transport direction is not counted as an abnormal part and is not stored in the total result buffer. The portion can be prevented from being stored, and high-speed image processing can be performed.

  The long object visual inspection apparatus of the present invention is suitable for visual inspection while conveying a long belt-like sheet.

It is a schematic block diagram which shows the whole long thing visual inspection apparatus of this invention. It is a block diagram which shows schematic structure of the image process means in the external appearance inspection apparatus of the elongate thing of this invention. In order to show the timing of imaging performed by the long object visual inspection apparatus of the present invention, the graph showing the relationship between the time t and the conveyance speed v, and the imaging of the long object 2 corresponding to the imaging timing indicated by the arrow in the graph It is the figure which showed the position where is started. FIG. 6 is a diagram showing a state of an image frame 21 that is sequentially imaged at regular time intervals with respect to a long object having a linear scratch. It is explanatory drawing for demonstrating writing and image processing of the imaged image corresponding to a 1st image memory or a 2nd image memory. It is a flowchart which shows the whole procedure of the image processing control in the image processing means of this invention. It is a flowchart which shows the procedure of the image processing control of the image memorize | stored in the 2nd image memory. FIG. 8 is a flowchart illustrating a procedure of image processing control for an image stored in a second image memory, following the flowchart of FIG. 7. FIG. It is a flowchart which shows the procedure of the image processing control of the image memorize | stored in the 1st image memory. 10 is a flowchart illustrating a procedure of image processing control of an image stored in a second image memory, following the flowchart of FIG. 9. In order to show the timing of imaging performed by a conventional long object visual inspection apparatus, a graph showing the relationship between the time t and the conveyance speed v, and the imaging of the long object 2 corresponding to the imaging timing indicated by the arrow in the graph It is the figure which showed the position which is started. It is explanatory drawing which showed the method of imaging so that it may have an overlap part in the conventional external appearance inspection apparatus of a long thing.

Explanation of symbols

1 Visual inspection device
2 Long objects
21 Image frame 22 Image processing area 23 Overlap part
3 Conveying means 31 Conveying roller
4 CCD camera (imaging means)
5 Lighting equipment
6 Image processing means
61 Counter section
62 Image capture unit 62a First image memory 62b Second image memory
63 NG total result buffer
64 First NG information result buffer
65 Second NG information result buffer
66 Memory 67 I / F section 68 Image processing program 69 Bidirectional bus
7 Judgment means 8 Encoder (distance measurement means)

Claims (3)

While a long object is continuously conveyed in the length direction by the conveying means, a long object is imaged for each predetermined imageable area by the imaging means, and the captured image is processed by the image processing means. In appearance inspection equipment,
Provided with a distance measuring means for detecting the moving distance of the long object conveyed by the conveying means,
The imaging means should capture images at regular time intervals,
Based on the detection result from the distance measuring means, the image processing means calculates the moving distance of the long object that has moved from the start of the imaging of the image to be processed to the start of the next imaging. An apparatus for inspecting the appearance of a long object, wherein a distance is specified as an image processing area in a single imageable area, and image processing is performed in the image processing area. The image processing means
Having a first image memory and a second image memory for storing an image captured by the imaging means, and alternately storing an image captured by the imaging means in the first image memory and the second image memory;
While taking a long object to store an image in one image memory, processing the image stored in the other image memory that was taken immediately before the image being taken The long object visual inspection apparatus according to claim 1. The image processing means
The image processing area has a first NG information result buffer and a second NG information result buffer for storing an abnormal part detected at the rear end in the transport direction, and the abnormal part of the image stored in the first image memory In the first NG information result buffer, the abnormal portion of the image stored in the second image memory is stored in the second NG information result buffer.
While setting the image processing area so that each image processing area overlaps at both ends in the conveyance direction of the long object,
The abnormal portion detected at the front end in the conveyance direction for the image being processed is collated with the abnormal portion detected at the rear end in the conveyance direction in the previous image, and the difference in position of each abnormal portion is determined in advance. 3. The long object visual inspection apparatus according to claim 2, wherein it is determined to be the same when the value is equal to or less than a set threshold value.

Images