Hole detection device

Abstract

To provide a hole detection device capable of reducing erroneous detection.SOLUTION: A hole detection device includes: a light source that irradiates a plate-like member moving in a first direction with light; a light detection portion that is arranged at a position for sandwiching the plate-like member together with the light source and can detect the light; and a determination portion that determines presence or absence of a hole in the plate-like member on the basis of an intensity profile of the light along a second direction intersecting the first direction. The determination portion acquires a target value of a length of the plate-like member along the second direction, determines an existence predicted range of edges of the plate-like member on the basis of the target value, detects a pair of edges of the plate-like member in the existence predicted range, and uses a range between the pair of edges in the second direction as a search range to search for the hole in the search range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiment relates to a hole detection device. [Background technology]

[0002] In a manufacturing line for plate-like members, a hole detection device for detecting hole defects is used, and in such a device, it is desirable to reduce false detections. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-216539 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the embodiment is to provide a hole detection device that can reduce false detections. [Means for solving the problem]

[0005] A hole detection device according to an embodiment includes a light source that irradiates light onto a plate-like member moving in a first direction, a light detection unit that is positioned so as to sandwich the plate-like member together with the light source and is capable of detecting the light, and a determination unit that determines the presence or absence of a hole in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction. The determination unit acquires a target value for the length of the plate-like member along the second direction, determines an expected range of existence of an edge of the plate-like member based on the target value, detects a pair of edges of the plate-like member within the expected range, defines a range between the pair of edges in the second direction as a search range, and searches for the hole within the search range.

[0006] A hole detection device according to an embodiment includes a light source that irradiates light onto a plate-like member moving in a first direction, a light detector that is disposed in a position sandwiching the plate-like member together with the light source and is capable of detecting the light, and a determination unit that determines whether or not a hole is present in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction. The light detector creates the intensity profile at predetermined time intervals. The determination unit determines the position where the intensity profile turns bright in a direction from the center toward the edge of the plate-shaped member in the second direction, calculates a moving average of the edge positions based on the plurality of intensity profiles, and when the intensity in the moving average in the new intensity profile is within a first intensity range, searches for the new intensity profile from the moving average toward the inside of the plate-shaped member and determines the position where the new intensity profile turns dark as the edge position of the plate-shaped member, and when the intensity in the moving average in the new intensity profile is within a second intensity range lower than the first intensity range, searches for the new intensity profile from the moving average toward the outside of the plate-shaped member and determines the position where the new intensity profile turns bright as the edge position of the plate-shaped member, determines the range between the pair of edge positions in the new intensity profile as a search range, and searches for the hole in the search range.

[0007] A hole detection device according to an embodiment includes a light source that irradiates light onto a plate-like member moving in a first direction, a light detection unit that is positioned so as to sandwich the plate-like member together with the light source and is capable of detecting the light, and a determination unit that determines whether or not a hole exists in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction. The light detection unit creates the intensity profiles at predetermined time intervals. The determination unit detects bright regions based on multiple intensity profiles and determines whether the bright regions are caused by the hole or a foreign object based on the shape of the bright regions. [Brief explanation of the drawings]

[0008] [Figure 1]FIG. 1 is a diagram showing a hole detection device according to a first embodiment. [Figure 2] 2(a) to 2(c) are diagrams showing the basic operation of the hole detection device according to the first embodiment. [Figure 3] FIG. 3 is a flowchart showing the basic operation of the hole detection device according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing step S1 of FIG. 3 in the first embodiment. [Figure 5] FIG. 5 is a diagram showing an example of a light intensity profile in the first embodiment. [Figure 6] FIG. 6 is a flowchart showing step S1 of FIG. 3 in the second embodiment. [Figure 7] 7(a) and (b) are diagrams showing an example of a light intensity profile in the second embodiment. [Figure 8] FIG. 8 is a flowchart showing step S2 of FIG. 3 in the third embodiment. [Figure 9] Figure 9(a) is a diagram showing examples of bright areas caused by holes in a plate-like member and bright areas caused by foreign matter, (b) is a diagram showing the shapes of these bright areas, and (c) is a diagram showing the pixels of the light detection unit that detect these bright areas. [Figure 10] FIG. 10 is a flowchart showing step S2 of FIG. 3 in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment FIG. 1 is a diagram showing a hole detection device according to this embodiment. As shown in FIG. 1, the hole detection device 1 according to this embodiment is a device that inspects whether or not a plate-shaped member 100 has a hole. The plate-shaped member 100 is, for example, a steel plate. The plate-shaped member 100 is, for example, about 0.5 to 2 m wide, about 0.1 to 5 mm thick, and about several hundred meters long, and is wound into a coil during storage and transportation. When inspecting for a hole, the plate-shaped member 100 is unwound from the coil, passes through the hole detection device 1, and is then rewound into the coil.

[0010] For ease of explanation, the width direction (second direction) of the plate-shaped member 100 in the hole detection device 1 will be referred to as the "X direction," the thickness direction of the plate-shaped member 100 as the "Z direction," and the movement direction (first direction) of the plate-shaped member 100 as the "Y direction." The X direction, Y direction, and Z direction are, for example, perpendicular to each other. Holes present in the plate-shaped member 100 penetrate the plate-shaped member 100 in the Z direction.

[0011] The hole detection device 1 is provided with a light source 10, a light detection unit 20, and a determination unit 30. The light source 10 is disposed across the entire width direction (X direction) of the plate-shaped member 100, and emits light L upward (Z direction). As a result, the light source 10 irradiates the light L across the entire width direction of the plate-shaped member 100 moving in the Y direction. The light L is, for example, visible light, but is not limited to this.

[0012] The light detection unit 20 is disposed in a position where it sandwiches the plate-shaped member 100 together with the light source 10. In the example shown in Fig. 1, the light source 10 is disposed below the plate-shaped member 100, and the light detection unit 20 is disposed above the plate-shaped member 100. However, this is not limitative, and it is sufficient that the plate-shaped member 100 is disposed between the light source 10 and the light detection unit 20 in the Z direction.

[0013] The light detection unit 20 can detect light L emitted from the light source 10. The light detection unit 20 is provided with, for example, multiple cameras 21. The multiple cameras 21 are arranged in a row along the X direction. This allows the light detection unit 20 to detect the presence or absence of light L across the entire width direction of the plate-shaped member 100. The light detection unit 20 can also detect light L that is emitted from the light source 10 and passes through the sides of the plate-shaped member 100. This allows the light detection unit 20 to create an intensity profile P of the light L along the X direction (second direction). The light detection unit 20 creates the intensity profile P at regular time intervals, for example, every 50 μsec to 100 μsec, and outputs the intensity profile P to the determination unit 30.

[0014] The determination unit 30 determines whether or not there is a hole in the plate-like member 100 based on the intensity profile P, and outputs the result. The determination unit 30 may also output a signal indicating the approximate size of the detected hole together with the signal indicating the presence of the hole.

[0015] Next, the operation of the hole detection device according to this embodiment will be described. 2(a) to 2(c) are diagrams showing the basic operation of the hole detection device according to this embodiment. FIG. 3 is a flowchart showing the basic operation of the hole detection device according to this embodiment. 2(a) to 2(c), the plate-like member 100 and the intensity profile P are depicted with their positions in the X direction corresponding to each other. The same applies to the drawings as will be described later.

[0016] 1 and 2(a), light L emitted from the light source 10 is blocked by the plate-shaped member 100. Furthermore, light L emitted from the light source 10 and passing through the side of the plate-shaped member 100 is directly incident on the light detection unit 20 and detected by the light detection unit 20. Therefore, in the intensity profile P output from the light detection unit 20, the light intensity is within a dark range I2 (second intensity range) in the range corresponding to the plate-shaped member 100, and the light intensity is within a bright range I1 (first intensity range) in the region corresponding to the side of the plate-shaped member 100. The bright range I1 is stronger than the dark range I2.

[0017] 2(a) and step S1 in Fig. 3, the determination unit 30 detects the widthwise edges 101 and 102 of the plate-shaped member 100 by detecting a position in the light intensity profile P where the light intensity changes from a dark range I2 to a light range I1 when searching from the inside to the outside of the plate-shaped member 100 (hereinafter referred to as a "light transition position"), or a position where the light intensity changes from a light range I1 to a dark range I2 when searching from the outside to the inside of the plate-shaped member 100 (hereinafter referred to as a "dark transition position"). The range between the edges 101 and 102 of the plate-shaped member 100 is set as a search range for searching for holes.

[0018] 2(a) and step S2 in Fig. 3, the determination unit 30 detects holes in the plate-shaped member 100. If there is no region in the intensity profile P where the light intensity falls within the bright range I1 (hereinafter also referred to as a "bright region") within the search range between the edge 101 and the edge 102, the determination unit 30 determines that no hole exists in the plate-shaped member 100 at a position corresponding to the intensity profile P.

[0019] 1 and 2(b), when a hole 110 is present in the plate-like member 100, the light detection unit 20 detects light L that has passed through the hole 110, and therefore a bright region is present within the search range in the intensity profile P. When the determination unit 30 detects a bright region within the search range between the edge 101 and the edge 102 in the intensity profile P, it determines that a hole 110 is present.

[0020] As shown in FIGS. 1 and 2(c), if a foreign object 200 is present near the plate-shaped member 100, the light L is also blocked by the foreign object 200, and the light intensity in the region of the intensity profile P corresponding to the foreign object 200 becomes a dark range I2. The foreign object 200 is, for example, scale peeled off the surface of the plate-shaped member 100, dust or insects that have flown in from the outside, etc. The region between the plate-shaped member 100 and the foreign object 200 becomes a bright region where the light intensity falls within the bright range I1, and it is necessary to prevent this bright region from being mistaken for a hole 110. A method for doing this will be described below.

[0021] FIG. 4 is a flowchart showing step S1 of FIG. 3 in this embodiment. FIG. 5 is a diagram showing an example of a light intensity profile in this embodiment.

[0022] 4, the determination unit 30 acquires a target plate width value W0 of the plate-shaped member 100. The target plate width value W0 is a target value for the width of the plate-shaped member 100, i.e., the length along the X direction, and is input to the hole detection device 1 from a manufacturing system for the plate-shaped member 100, for example.

[0023] 4 and 5, the determination unit 30 determines predicted edge presence ranges R1 and R2 of the plate-shaped member 100 based on the target plate width value W0. The predicted presence range R1 is a range in which the edge 101 of the plate-shaped member 100 is likely to exist in the X direction, and the predicted presence range R2 is a range in which the edge 102 of the plate-shaped member 100 is likely to exist in the X direction.

[0024] For example, the determination unit 30 determines the predicted existence ranges R1 and R2 based on the plate width target value W0, the width variation range ΔW of the plate-shaped member 100, and the position variation range ΔX in the X direction of the plate-shaped member 100. The length variation range ΔW and the position variation range ΔX are input to the hole detection device 1 from, for example, a manufacturing system for the plate-shaped member 100.

[0025] For example, when the X coordinate is set to 0 at the position where the center of the plate-shaped member 100 in the X direction is expected to be, the expected range R1 of the edge 101 on the -X direction side of the plate-shaped member 100 can be set to a range of (-W0 / 2-ΔW / 2-ΔX / 2) to (-W0 / 2+ΔW / 2+ΔX / 2).The expected range R2 of the edge 102 on the +X direction side can be set to a range of (+W0 / 2-ΔW / 2-ΔX / 2) to (+W0 / 2+ΔW / 2+ΔX / 2).

[0026] Next, as shown in step S13 of Fig. 4 and Fig. 5, the determination unit 30 detects the edge of the plate-shaped member 100 within the expected presence range R1. Specifically, the determination unit 30 determines the position where the light intensity becomes brighter when searching the intensity profile P within the expected presence range R1 along the direction from the center of the plate-shaped member 100 in the X direction toward the edge (-X direction) as the position of the edge 101. Alternatively, the determination unit 30 determines the position where the light intensity becomes darker when searching the intensity profile P within the expected presence range R1 along the direction from the side of the plate-shaped member 100 toward the center of the X direction (+X direction).

[0027] Similarly, when the determination unit 30 searches for the intensity profile P within the expected existence range R2 along the direction from the center in the X direction of the plate-shaped member 100 toward the end (+X direction), the determination unit 30 determines the position where the light intensity turns bright as the position of the edge 102. Alternatively, when the determination unit 30 searches for the intensity profile P within the expected existence range R2 along the direction from the side of the plate-shaped member 100 toward the center in the X direction (-X direction), the determination unit 30 determines the position where the light intensity turns dark as the position of the edge 102.

[0028] 4 and 5, the area between the edge 101 and the edge 102 detected in step S13 is set as a search range R3 for searching for holes. Note that the actual width of the plate-like member 100 includes errors due to the process, so the length of the search range R3 does not necessarily match the plate width target value W0.

[0029] Next, as shown in step S2 of Fig. 3, the determination unit 30 searches for a hole in the search range R3. That is, if there are positions in the search range R3 where the intensity profile P turns bright and positions where it turns dark, the determination unit 30 determines the bright region between these positions as the hole 110. Next, the determination unit 30 outputs the detection result of the hole 110.

[0030] Next, the effects of this embodiment will be described. 4 and 5, according to this embodiment, a target plate width value W0 is acquired, and edge existence ranges R1 and R2 are determined based on this target plate width value, and edges 101 and 102 of a plate-like member 100 are detected within these expected existence ranges R1 and R2. Then, the area between the detected edges 101 and 102 is set as a hole search range R3, and holes are searched for within the search range R3.

[0031] 5, foreign matter 200 existing outside the search range R3 is excluded from the search target, and therefore a bright region between the plate-shaped component 100 and the foreign matter 200 where the light intensity falls within the bright range I1 is not mistakenly detected as a hole. As a result, it is possible to suppress the mistaken detection of a hole caused by the foreign matter 200.

[0032] Furthermore, by determining the ranges R1 and R2 where the edges are expected to exist based on the target plate width value W0, the edges 101 and 102 of the plate-like member 100 can be detected accurately and efficiently.

[0033] If a hole exists within the predicted existence range R1 or R2, the edge of the hole may be mistakenly recognized as the edge of the plate-shaped member 100, and the hole may not be detected. However, the edge of the plate-shaped member 100, i.e., the area a certain distance from the edge, is inherently prone to defects and is trimmed in a later process, so hole detection is often not required in the first place. For this reason, there is little practical problem even if holes within the predicted existence range are not detected.

[0034] <Second embodiment> The view showing the hole detection device according to this embodiment is similar to FIG. The diagrams showing the basic operation of the hole detection device according to this embodiment are the same as those in FIGS. 2(a) to 2(c) and 3. FIG. FIG. 6 is a flowchart showing step S1 of FIG. 3 in this embodiment. 7(a) and (b) are diagrams showing an example of the light intensity profile in this embodiment.

[0035] Similar to the hole detection device according to the first embodiment, the hole detection device according to this embodiment acquires a light intensity profile P at predetermined time intervals and outputs it to the determination unit 30. The determination unit 30 then detects the edges 101 and 102 for each intensity profile P. For example, the determination unit 30 determines the positions where the intensity profile P becomes bright in the direction from the center to the edge in the X direction of the plate-shaped member 100 as the positions of the edges 101 and 102 of the plate-shaped member 100. In this way, the determination unit 30 detects and stores the positions of the edges 101 and 102 at predetermined time intervals.

[0036] 6, the determination unit 30 calculates a moving average of the positions of the edges 101 and 102 of the plate-shaped member 100 based on the most recent intensity profiles P. For simplicity of explanation, only the edge 102 on the +X direction side will be described below, but the same applies to the edge 101 on the −X direction side.

[0037] Next, as shown in step S22 of Fig. 6 and Figs. 7(a) and (b), the determination unit 30 determines the light intensity at the moving average V2 of the edge 102 in the newly input intensity profile P. The moving average V2 of the position of the edge 102 is the position in the new intensity profile P where the edge 102 is most likely to exist. Therefore, it is highly likely that the edge 102 is actually located near the moving average V2.

[0038] As shown in Figure 7(a), if the light intensity at the moving average V2 is within the bright range I1 (first intensity range), as shown in step S23 of Figure 6, a new intensity profile P is searched from the moving average V2 toward the inside of the plate-shaped member 100, and as shown in step S24, the position where the new intensity profile P becomes dark is determined to be the position of the edge 102 of the plate-shaped member 100.

[0039] On the other hand, as shown in Figure 7(b), if the light intensity at the moving average V2 is within the dark range I2 (second intensity range), as shown in step S25 of Figure 6, a new intensity profile P is searched from the moving average V2 toward the outside of the plate-shaped member 100, and as shown in step S26, the position where the new intensity profile P turns bright is determined to be the position of the edge 102 of the plate-shaped member 100.

[0040] Similarly, the position of the edge 101 is detected by the method shown in steps S21 to S26 in Fig. 6. Next, as shown in step S27 in Fig. 6, the range between the positions of the pair of edges 101 and 102 in the new intensity profile P is set as a search range for searching for holes. Next, as shown in step S2 in Fig. 3, the determination unit 30 searches for holes within the search range.

[0041] Next, the effects of this embodiment will be described. According to this embodiment, by searching from the moving average toward the inside or outside of the plate-shaped member 100 based on the light intensity in the moving average of the edge of the plate-shaped member 100, the edges 101 and 102 of the plate-shaped member 100 can be accurately detected with a high probability. As a result, foreign matter 200 existing outside the edge can be excluded from the search range, and the bright area between the plate-shaped member 100 and the foreign matter 200 can be prevented from being mistakenly detected as a hole. As a result, the mistaken detection of a hole caused by the foreign matter 200 can be prevented.

[0042] Note that if a hole exists at the position of the moving average in the intensity profile P shown in FIG. 7(a), or if a hole exists between the moving average and an edge in the intensity profile P shown in FIG. 7(b), the edges of these holes may be mistaken for the edge of the plate-like component 100, and these holes may not be detected. However, the moving average is the position where the edge is most likely to exist, and the edge is likely to exist near the moving average, so this possibility is low. Furthermore, even if a hole exists at the moving average or between the moving average and an edge, as described in the first embodiment, hole detection is often not required at the edge of the plate-like component 100, and this poses little practical problem.

[0043] <Third embodiment> The view showing the hole detection device according to this embodiment is similar to FIG. The diagrams showing the basic operation of the hole detection device according to this embodiment are the same as those in FIGS. 2(a) to 2(c) and 3. FIG.

[0044] FIG. 8 is a flowchart showing step S2 of FIG. 3 in this embodiment. Figure 9(a) is a diagram showing examples of bright areas caused by holes in a plate-like member and bright areas caused by foreign matter, (b) is a diagram showing the shapes of these bright areas, and (c) is a diagram showing the pixels of the light detection unit that detect these bright areas.

[0045] First, as shown in step S1 of FIG. 3, the determining unit 30 detects the edges 101 and 102 of the plate-like member 100.

[0046] Next, as shown in step S31 of Fig. 8, the determination unit 30 detects a bright region 120 where the light intensity falls within the bright range I1 (first intensity range). As shown in Fig. 9(a), the bright region 120 includes a bright region 121 caused by the hole 110 in the plate-shaped member 100 and a bright region 122 detected between the plate-shaped member 100 and the foreign substance 200. Because each intensity profile P contains only information about a specific position in the Y direction, if the foreign substance 200 is located at a position distant from the plate-shaped member 100, the determination unit 30 will detect the area between the plate-shaped member 100 and the foreign substance 200 as a bright region 122. At this stage, the determination unit 30 cannot distinguish between the bright region 121 caused by the hole and the bright region 122 caused by the foreign substance, and will detect both as bright regions 120.

[0047] 8, the determination unit 30 calculates the aspect ratio of the bright region 120. The aspect ratio of the bright region 120 is the ratio (Lx / Ly) of the length Lx in the X direction of the bright region 120 to the length Ly in the Y direction of the bright region 120.

[0048] 9(b), the aspect ratio of a bright region 121 caused by a hole 110 in the plate-shaped member 100 is often relatively small, while the aspect ratio of a bright region 122 detected between the plate-shaped member 100 and a foreign substance 200 is often relatively large. For example, as shown in FIG. 9(c), the aspect ratio of the bright region 120 can be calculated by counting the number of pixels in the light detection unit 20 whose light intensity falls within the bright range I1 along the X and Y directions.

[0049] Next, as shown in step S33 of Fig. 8, the determination unit 30 determines that a bright region 120 having an aspect ratio greater than the reference value is a bright region 122 detected between the plate-like member 100 and the foreign substance 200, and excludes the possibility that it is a hole. On the other hand, the determination unit 30 determines that a bright region 120 having an aspect ratio equal to or less than the reference value is a bright region 121 caused by a hole 110, and determines that a hole 110 is present. The reference value for the aspect ratio may be determined taking into consideration the aspect ratios of bright regions 120 detected in the past.

[0050] Next, the effects of this embodiment will be described. In this embodiment, the detected bright region 120 is distinguished based on the aspect ratio into a bright region 121 caused by the hole 110 and a bright region 122 caused by the foreign substance 200. This makes it possible to prevent the bright region 122 caused by the foreign substance 200 from being mistaken for a hole 110.

[0051] The aspect ratio of the bright region 120 may be defined as the ratio (Ly / Lx) of the length Ly in the Y direction to the length Lx in the X direction of the bright region 120, and a bright region 120 with an aspect ratio greater than a reference value may be determined to be a bright region 121 caused by a hole.

[0052] <Fourth embodiment> The view showing the hole detection device according to this embodiment is similar to FIG. The diagrams showing the basic operation of the hole detection device according to this embodiment are the same as those in FIGS. 2(a) to 2(c) and 3. FIG. FIG. 10 is a flowchart showing step S2 of FIG. 3 in this embodiment.

[0053] First, as shown in step S1 of FIG. 3, the determining unit 30 detects the edges 101 and 102 of the plate-like member 100.

[0054] 9(a) and step S41 in FIG. 10, the determination unit 30 detects a bright region 120 where the light intensity falls within the bright range I1. As described in the third embodiment, the bright region 120 includes a bright region 121 caused by a hole in the plate-like member 100 and a bright region 122 detected between the plate-like member 100 and the foreign substance 200.

[0055] Next, as shown in step S42 of FIG. 10, the determination unit 30 calculates the width of the bright region 120, that is, the ratio (Lxmax / Lxmin) of the maximum width (Lxmax) of the bright region 120 to the minimum length (Lxmin) in the X direction.

[0056] As shown in Fig. 9(b), the shape of a bright region 122 detected between the plate-like member 100 and the foreign substance 200 is often rectangular, and the value of this ratio is often close to 1. On the other hand, the shape of a bright region 121 caused by a hole in the plate-like member 100 is often close to circular, and the value of this ratio is often greater than 1. For example, as shown in Fig. 9(c), the ratio value of the bright region 120 can be calculated by counting the number of pixels in the light detection unit 20 whose light intensity falls within the bright range I1 along the X direction.

[0057] Next, as shown in step S43 of Fig. 10, the determination unit 30 determines that a bright region 120 having a ratio value (Lxmax / Lxmin) smaller than the reference value is a bright region 122 detected between the plate-like member 100 and the foreign substance 200, and excludes the possibility of it being a hole. On the other hand, a bright region 120 having a ratio value (Lxmax / Lxmin) equal to or greater than the reference value is determined to be a bright region 121 caused by a hole 110, and determines that a hole 110 is present. The reference value of the ratio value (Lxmax / Lxmin) may be determined taking into consideration the shape of bright regions detected in the past.

[0058] Next, the effects of this embodiment will be described. In this embodiment, the detected bright region 120 is classified into a bright region 121 caused by a hole and a bright region 122 caused by a foreign substance based on the ratio of the maximum width to the minimum width (Lxmax / Lxmin). This makes it possible to prevent the bright region 122 caused by a foreign substance from being mistaken for a hole 110.

[0059] The index ratio value may be defined as the ratio (Lxmin / Lxmax) of the minimum length value (Lxmin) to the maximum length value (Lxmax) in the X direction, and a bright area whose ratio value is smaller than a reference value may be determined to be a bright area caused by a hole.

[0060] Furthermore, the third and fourth embodiments may be combined and implemented. That is, after detecting the bright region 120, the bright region 121 caused by a hole and the bright region 122 caused by a foreign substance may be distinguished from each other by taking into consideration both the aspect ratio (Lx / Ly) of the bright region 120 and the ratio of the maximum value to the minimum value (Lxmax / Lxmin).

[0061] For example, only bright regions 120 whose aspect ratio is less than or equal to a reference value and whose ratio value (Lxmax / Lxmin) is greater than or equal to the reference value may be judged to be bright regions 121 caused by holes, or only bright regions 120 whose aspect ratio is greater than the reference value and whose ratio value (Lxmax / Lxmin) is less than the reference value may be judged to be bright regions 122 caused by foreign matter, and other bright regions 120 may be judged to be bright regions 121 caused by holes.

[0062] According to the embodiment described above, it is possible to realize a hole detection device that can reduce false detections.

[0063] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can also be implemented in combination with each other.

[0064] The present invention includes the following aspects.

[0065] (Appendix 1) a light source that irradiates light onto a plate-like member that moves in a first direction; a light detection unit that is disposed at a position sandwiching the plate-like member together with the light source and is capable of detecting the light; a determination unit that determines whether or not a hole exists in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction; Equipped with The determination unit acquiring a target value for the length of the plate-like member along the second direction; determining an expected range of the edge of the plate-like member based on the target value; Detecting a pair of edges of the plate-like member within the predicted presence range; a range between the pair of edges in the second direction is set as a search range; a hole detection device that searches for the hole in the search range;

[0066] (Appendix 2) A hole detection device as described in Appendix 1, wherein the judgment unit determines the predicted existence range based on the target value, the range of variation of the length of the plate-shaped member along the second direction, and the range of variation of the position of the plate-shaped member in the second direction.

[0067] (Appendix 3) The hole detection device described in Appendix 1 or 2, wherein the determination unit determines the position of the edge as the position where the intensity profile turns bright along the direction from the center of the plate-like member in the second direction toward the end within the expected existence range.

[0068] (Appendix 4) a light source that irradiates light onto a plate-like member that moves in a first direction; a light detection unit that is disposed at a position sandwiching the plate-like member together with the light source and is capable of detecting the light; a determination unit that determines whether or not a hole exists in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction; Equipped with the light detection unit creates the intensity profile at predetermined time intervals; The determination unit a position where the intensity profile brightens in a direction from the center of the plate-shaped member toward the end in the second direction is defined as a position of an edge of the plate-shaped member; calculating a moving average of the edge position based on a plurality of the intensity profiles; When the intensity in the moving average of the new intensity profile is within a first intensity range, the new intensity profile is searched from the moving average toward the inside of the plate-like member, and the position where the new intensity profile becomes dark is determined as the position of the edge of the plate-like member; When the intensity in the moving average in the new intensity profile is within a second intensity range that is lower than the first intensity range, the new intensity profile is searched from the moving average toward the outside of the plate-like member, and the position where the new intensity profile turns bright is determined to be the position of the edge of the plate-like member; a range between the positions of the pair of edges in the new intensity profile is set as a search range; a hole detection device that searches for the hole in the search range;

[0069] (Appendix 5) a light source that irradiates light onto a plate-like member that moves in a first direction; a light detection unit that is disposed at a position sandwiching the plate-like member together with the light source and is capable of detecting the light; a determination unit that determines whether or not a hole exists in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction; Equipped with the light detection unit creates the intensity profile at predetermined time intervals; The determination unit detecting bright regions based on a plurality of said intensity profiles; A hole detection device that determines whether the bright area is caused by the hole or a foreign object based on the shape of the bright area.

[0070] (Appendix 6) The said judgment is Calculating a ratio of the length of the bright region in the second direction to the length of the bright region in the first direction; 6. The hole detection device according to claim 5, wherein the bright region where the value of the ratio is equal to or less than a reference value is determined to be a bright region caused by the hole.

[0071] (Appendix 7) The said judgment is Calculating a ratio of a maximum length of the bright region in the second direction to a minimum length of the bright region in the second direction; 6. The hole detection device according to claim 5, wherein the bright region where the value of the ratio is equal to or less than a reference value is determined to be a bright region caused by the hole.

[0072] (Appendix 8) 8. The hole detection device according to claim 1, wherein the plate-like member is a steel plate. [Explanation of symbols]

[0073] 1: Hole detection device 10:Light source 20: Light detection unit 21: Camera 30: Judgment section 100: Plate-shaped member 101, 102: Edge 110: Hole 120: Light area 121: Bright area caused by a hole 122: Bright area caused by foreign matter 200: Foreign object I1: Bright range I2: Dark range L:Light P: Intensity profile R1, R2: Predicted range of existence R3: Search range V2: Moving average W0: Target plate width

Claims

1. a light source that irradiates light onto a plate-like member that moves in a first direction; a light detection unit that is disposed in a position sandwiching the plate-like member together with the light source and is capable of detecting the light; a determination unit that determines whether or not a hole is present in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction; Equipped with The determination unit is obtaining a target value for the length of the plate-like member along the second direction; determining an expected range of the edge of the plate-like member based on the target value; Detecting a pair of edges of the plate-like member within the predicted presence range; a range between the pair of edges in the second direction is set as a search range; A hole detection device that searches for the hole in the search range.

2. The hole detection device according to claim 1 , wherein the determination unit determines the predicted existence range based on the target value, a range of variation in the length of the plate-shaped member along the second direction, and a range of variation in the position of the plate-shaped member in the second direction.

3. The hole detection device according to claim 1 , wherein the determination unit determines that the position at which the intensity profile brightens along a direction from the center of the plate-like member in the second direction toward the end thereof within the predicted existence range is the position of the edge.

4. a light source that irradiates light onto a plate-like member that moves in a first direction; a light detection unit that is disposed in a position sandwiching the plate-like member together with the light source and is capable of detecting the light; a determination unit that determines whether or not a hole is present in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction; Equipped with The light detection unit creates the intensity profile at a predetermined time interval, The determination unit is a position where the intensity profile becomes bright in a direction from a center portion of the plate-like member toward an end portion in the second direction is defined as a position of an edge of the plate-like member; calculating a moving average of the edge position based on a plurality of the intensity profiles; When the intensity in the moving average in the new intensity profile is within a first intensity range, the new intensity profile is searched from the moving average toward the inside of the plate-like member, and the position where the new intensity profile becomes dark is determined as the position of the edge of the plate-like member; When the intensity in the moving average in the new intensity profile is within a second intensity range that is lower than the first intensity range, the new intensity profile is searched from the moving average toward the outside of the plate-like member, and the position where the new intensity profile turns bright is determined as the position of the edge of the plate-like member; a range between the positions of the pair of edges in the new intensity profile is set as a search range; A hole detection device that searches for the hole in the search range.

5. a light source that irradiates light onto a plate-like member that moves in a first direction; a light detection unit that is disposed in a position sandwiching the plate-like member together with the light source and is capable of detecting the light; a determination unit that determines whether or not a hole is present in the plate-like member based on an intensity profile of the light along a second direction that intersects with the first direction; Equipped with The light detection unit creates the intensity profile at a predetermined time interval, The determination unit is Detecting bright regions based on a plurality of said intensity profiles; A hole detection device that determines whether the bright area is caused by the hole or a foreign object based on the shape of the bright area.

6. The above judgment is Calculating a ratio of a length of the bright region in the second direction to a length of the bright region in the first direction; The hole detection device according to claim 5 , wherein the bright region where the value of the ratio is equal to or smaller than a reference value is determined to be a bright region caused by the hole.

7. The above judgment is Calculating a ratio of a maximum length of the bright region in the second direction to a minimum length of the bright region in the second direction; The hole detection device according to claim 5 , wherein the bright region where the value of the ratio is equal to or smaller than a reference value is determined to be a bright region caused by the hole.

8. 6. The hole detection device according to claim 1, wherein the plate-like member is a steel plate.

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