JP2020134491A - Inspection unit, program and recording medium - Google Patents

Abstract

To provide an inspection unit capable of accurately detecting defects even by a non-skilled person.SOLUTION: An inspection unit 10 detects defects on an object surface 80S, and comprises: a projection device 40 for projecting a projection image 60 formed of a bright part 62 and a dark part 64 to the object surface 80S; and an imaging unit 50 for imaging the object surface 80S. The inspection unit 10 projects the projection image 60 to the object surface 80S so as to shift the projection image once or more times, by the projection device 40, and images the object surface 80S by the imaging unit 50 for detecting defects in inspection processing. The inspection unit 10 projects once or more times, each of the bright part 62 and the dark part 64 to at least one prescribed position 88 on the object surface 80S by the projection device 40, and images two or more images by the imaging unit 50 in inspection preparation processing.SELECTED DRAWING: Figure 11

Description

The present invention relates to an inspection unit for detecting defects such as scratches and dents formed on the surface of an object.

For example, Patent Document 1 discloses this type of inspection unit.

With reference to FIG. 19, the defect inspection device (inspection unit) 90 disclosed in the second embodiment of Patent Document 1 includes a light source (projection device) 92, an image sensor (imaging device) 94, and an arithmetic unit (calculation device). It is equipped with a processing device) 96. The projection device 92 projects a pattern 922 composed of a bright portion and a dark portion on the surface of an object (object) 98 moving at a predetermined speed. The photographing device 94 photographs a plurality of patterns 922 projected on the surface of the object 98 at predetermined time intervals, and transmits the captured images to the processing device 96. The processing device 96 obtains the difference (contrast) between the maximum brightness and the minimum brightness at each point on the surface of the object 98 from the received plurality of images, and creates a difference image by this. The processing device 96 detects defects such as scratches and dents formed on the surface of the object 98 based on the created difference image. According to Patent Document 1, defects can be clearly identified by the difference image.

Japanese Patent No. 4147682

According to the inspection unit of Patent Document 1, it is possible to mechanize an inspection process that conventionally relies on the visual inspection of a person skilled in inspection. However, when inspecting using a projection device and an imaging device as in Patent Document 1, it is necessary to set various inspection parameters such as the brightness of the pattern projected on the object, the exposure time in imaging, and the sensitivity. .. In general, it is necessary to be skilled in inspection in order to set such inspection parameters. That is, even if the inspection unit of Patent Document 1 is used, it is difficult for a person who is not skilled in inspection to accurately detect a defect.

Therefore, an object of the present invention is to provide an inspection unit capable of accurately detecting defects even if the person is not skilled in inspection.

In the process of advancing research, the researcher of the present invention has a defect in the ratio (brightness ratio) between the width of the bright part (bright part width LW) and the width of the dark part (dark part width BW) in the pattern projected on the object. It was found that it has a great influence on the detection accuracy of. For example, when the surface color of an object is black, defects can be sufficiently detected by a predetermined light-dark ratio, but when the surface color of the object is white, defects cannot be sufficiently detected by the same light-dark ratio. It was.

As a result of further research, the researcher of the present invention can accurately detect defects by adjusting the dark area width according to the surface condition of the object while using a constant bright area width (appropriate). We found that a light-dark ratio can be obtained. Further, by projecting a dark part and a bright part onto a predetermined position on the surface of the object (for example, one point on the surface of the object) and taking a picture, an appropriate dark part width can be obtained based on the shooting result of the predetermined position. I found that it was possible. Based on this new finding, the present invention provides the following inspection units, programs and storage media.

The present invention, as the first inspection unit,
An inspection unit for detecting defects on the target surface.
The inspection unit includes a projection device and an imaging device.
The projection device can project the projected image onto the target surface so as to shift along the shift direction.
The photographing device can photograph the target surface, and can photograph the target surface.
The projected image includes one or more bright areas and one or more dark areas having a lower brightness than the bright areas.
By projecting the projected image onto the target surface so as to shift one or more times along the shift direction, the bright portion and the dark portion can be projected at all positions on the target surface.
The inspection unit is capable of performing inspection processing and inspection preparation processing.
In the inspection process, the inspection unit projects the projected image onto the target surface so as to shift the projected image one or more times along the shift direction by the projection device, and photographs the target surface by the imaging device. And thereby detect the defect
In the inspection preparation process, the inspection unit projects the bright part and the dark part one or more times on at least one predetermined position on the target surface by the projection device, and the inspection unit 2 An inspection unit for capturing the above images is provided.

Further, the present invention is a first inspection unit as a second inspection unit.
The inspection unit is provided with a processing device.
The processing device is communicatively connected to each of the projection device and the photographing device.
The inspection preparation process includes a projection preparation process.
In the projection preparation process, the processing device performs one or more dark portion width adjustment processes while changing the dark portion width.
In each of the dark portion width adjusting processes, the processing device projects the bright portion and the dark portion one or more times with respect to the predetermined position by the projection device, and two or more images taken by the photographing apparatus. From the image, the contrast which is the difference between the maximum value of the brightness and the minimum value of the brightness at the predetermined position is acquired.
The processing device provides an inspection unit that acquires the dark portion width in the inspection process based on one or more of the contrasts acquired by the dark portion width adjusting process in the projection preparation process.

Further, the present invention is a second inspection unit as a third inspection unit.
In addition to the projection preparation process, the inspection preparation process includes an imaging preparation first process and an imaging preparation second process.
Before the projection preparation process, the processing device performs the shooting preparation first process,
In the first process of preparing for shooting, the processing device performs the first process of adjusting shooting parameters one or more times while changing the shooting parameters that define the brightness of the shooting device.
In each of the first processings for adjusting the imaging parameters, the processing apparatus projects the bright portion at least once with respect to the predetermined position by the projection apparatus, and the imaging apparatus captures one or more images. , Acquires the maximum brightness which is the maximum value of the brightness at the predetermined position.
In the first process of preparing for shooting, the processing device acquires a provisionally set value of the shooting parameter based on one or more of the maximum luminances acquired by the first process of adjusting the shooting parameter.
In the projection preparation process, the processing device takes a picture by the taking picture device using the provisional set value of the picture taking parameter.
After the projection preparation process, the processing device performs the shooting preparation second process.
In the shooting preparation second processing, the processing device performs one or more shooting parameter adjustment second processing while changing the shooting parameters.
In each of the second processings for adjusting the imaging parameters, the processing apparatus projects the bright portion at least once with respect to the predetermined position by the projection apparatus, and the imaging apparatus captures one or more images. , Acquires the maximum brightness which is the maximum value of the brightness at the predetermined position.
The processing device provides an inspection unit that acquires a set value of the imaging parameter in the inspection process based on one or more of the maximum luminances acquired by the imaging parameter adjustment second process in the imaging preparation second process. To do.

Further, the present invention is a third inspection unit as a fourth inspection unit.
The imaging parameters provide an inspection unit that is the exposure time and sensitivity of the imaging apparatus.

Further, the present invention, as a first program,
Provided is a program for operating a computer as a processing device in any of the second to fourth inspection units.

Further, the present invention comprises the first storage medium.
A storage medium for storing the first program is provided.

The inspection unit according to the present invention can perform inspection preparation processing in addition to inspection processing for detecting defects. In this inspection preparation process, the inspection unit projects two or more images by projecting each of the bright part and the dark part one or more times with respect to at least one predetermined position on the target surface. As a result, an image when the bright part is projected (bright image) and an image when the dark part is projected (dark image) are obtained at a predetermined position. The inspection unit can prepare an appropriate dark portion width (inspection dark portion width) in the inspection process based on the bright image and the dark image at a predetermined position. For example, the inspection unit can prepare the inspection dark area width based on the contrast, which is the difference between the brightness of the bright image and the brightness of the dark image. That is, according to the present invention, it is possible to provide an inspection unit capable of accurately detecting defects even if the person is not skilled in inspection.

It is a figure which shows typically the inspection unit in embodiment of this invention together with an object. It is a block block diagram which shows the inspection unit of FIG. It is a figure which shows the projection image of the inspection unit of FIG. 1 partially. It is a figure which shows the inspection method by the inspection unit of FIG. The projected image of FIG. 3 projected on the object surface is schematically shown. It is a flowchart which shows the inspection process of the inspection unit of FIG. It is a figure which shows the photographed image, the MAX image, the MIN image and the SSMM image in the inspection process of FIG. It is a figure which shows the display example of the defect displayed on the display device in the inspection process of FIG. It is a figure which shows the modification of the projection image of FIG. It is a figure which shows another modification of the projection image of FIG. It is a figure which shows typically the relationship between the dark part width and contrast when the projected image of FIG. 3 is projected on the object surface. It is a figure which shows the inspection preparation method by the inspection unit of FIG. It is a flowchart which shows the process from the inspection preparation process to the inspection process of the inspection unit of FIG. It is a figure which shows the display example of the selection screen displayed on the display device in the inspection preparation process of FIG. It is a flowchart which shows the 1st process of preparation for photography (preparation process of photography), the process of preparation for projection, and the 2nd process of preparation for photography (preparation process of photography) in the inspection preparation process of FIG. It is a flowchart which shows the shooting preparation process of FIG. It is a flowchart which shows the projection preparation process of FIG. It is a flowchart which shows the specific example of the shooting preparation process of FIG. It is a flowchart which shows the specific example of the projection preparation process of FIG. It is a figure which shows the surface defect inspection unit of Patent Document 1. FIG.

Referring to FIG. 1, the inspection unit 10 according to the embodiment of the present invention is a surface defect inspection unit for detecting defects on the target surface 80S of the object 80. The inspection unit 10 projects a projected image 60, which is an image having a predetermined pattern, onto the target surface 80S, and captures the image projected on the target surface 80S to remove scratches, dents, or the like formed on the target surface 80S. Detect defects.

As can be understood from the defect detection method described above, the target surface 80S preferably has a high light reflectance capable of specularly reflecting the projected projected image 60. More specifically, the target surface 80S is preferably a glossy and smooth surface. The preferred target surface 80S is, for example, a mirror surface, a painted surface of an article, a plated surface of an article, a glass surface, or a film surface. The inspection unit 10 can detect defects having a diameter of about 0.1 mm and a depth of about 0.0005 mm formed on the target surface 80S. However, the present invention is not limited to this, and the gloss, luster, and smoothness of the target surface 80S may be in accordance with the detection accuracy required for detecting defects. Further, the material, size and shape of the object 80 are not particularly limited. For example, the object 80 may be an opaque article or a transparent glass in which the inside of the article can be seen through.

The object 80 in the present embodiment is, for example, a resin portion of a car door mirror, and is small enough to be placed on a general desk-sized inspection table 12. Further, the inspection unit 10 in the present embodiment is arranged on the inspection table 12 as a whole. However, the present invention is not limited to this, and the arrangement of the inspection unit 10 and the size of the entire inspection unit 10 can be variously modified according to the object 80. For example, the object 80 may be a relatively large article such as a car body. In this case, the inspection unit 10 may be incorporated in a wall-shaped inspection facility provided around the object 80. Further, in order to inspect a plurality of parts of the target surface 80S at the same time, a plurality of inspection units 10 corresponding to the plurality of parts may be provided.

Hereinafter, first, various devices constituting the inspection unit 10 in the present embodiment will be described.

Referring to FIGS. 1 and 2, the inspection unit 10 in the present embodiment includes a processing device 20, a control device 30, a projection device 40, and a photographing device 50. The projection device 40 is an electronic device capable of projecting the projected image 60, and the photographing device 50 is an electronic device capable of photographing the projected projected image 60. The processing device 20 and the control device 30 are electronic devices capable of controlling each of the projection device 40 and the photographing device 50.

Referring to FIG. 3, the projected image 60 in the present embodiment is composed of a plurality of bright areas 62 and a plurality of dark areas 64. The bright part 62 and the dark part 64 are arranged alternately in the lateral direction. Each of the bright portion 62 and the dark portion 64 extends linearly along the vertical direction orthogonal to the horizontal direction while maintaining a constant size in the horizontal direction. In the present embodiment, the bright portion width LW, which is the size of the bright portion 62 in the lateral direction, is the same for all the bright portions 62, and the dark portion width BW, which is the size of the dark portion 64 in the lateral direction, is the same for all dark portions 64. Is the same in. That is, the projected image 60 is a pattern image in which the bright portion 62 and the dark portion 64 are periodically arranged in the lateral direction. However, as will be described later, the projected image in the present invention is not limited to the projected image 60 of the present embodiment, and can be variously deformed.

Referring to FIG. 1 together with FIG. 3, the projection device 40 according to the present embodiment is a general-purpose lighting device, and includes a large number of light emitting elements (not shown) capable of emitting light of various colors. There is. The light emitting element is, for example, a micro LED (light emitting diode). The light emitting elements are arranged two-dimensionally. The projection device 40 emits and projects the projected image 60 by changing the brightness of the light emitted by each of the light emitting elements. The bright portion 62 of the projected image 60 is formed by a light emitting element that emits high-intensity light. On the other hand, the dark portion 64 of the projected image 60 is formed by a light emitting element that emits low-luminance light, or is formed by a light emitting element that does not emit light. That is, the projected image 60 includes one or more bright areas 62 and one or more dark areas 64 having a brightness lower than that of the bright areas 62.

Referring to FIGS. 3 and 4, according to the present embodiment, the bright portion 62 of the projected image 60 is white and the dark portion 64 is black. However, as long as the brightness of the bright portion 62 is higher than the brightness of the dark portion 64, the colors and brightness of the bright portion 62 and the dark portion 64 are not particularly limited. For example, the color of the bright part 62 may be bright pink, and the color of the dark part 64 may be dark red. Further, as long as such a projected image 60 can be projected, the mechanism of the projection device 40 is not limited to the present embodiment.

With reference to FIGS. 1 and 4, the projection device 40 can adjust the position and orientation of the light emitting surface. The projection device 40 is arranged so that the projected image 60 can be projected on the entire target surface 80S. The projected image 60 is projected obliquely from above with respect to the target surface 80S, whereby the projected image 60P is formed on and around the target surface 80S. The width of each of the bright portion 62 and the dark portion 64 in the projected image 60P is, for example, about several mm.

Referring to FIG. 4, the projection direction of the projected image 60 is oblique to the surface on which the object 80 is placed. As a result, the ratio (aspect ratio) of the size of the projected image 60P in the horizontal direction to the size in the vertical direction is different from the aspect ratio of the projected image 60. Further, in general, the target surface 80S has a three-dimensional shape, and the projected image 60P is partially distorted as compared with the projected image 60. However, in the present embodiment, it is not necessary to consider the difference between the projected image 60 and the projected image 60P when explaining the function of the inspection unit 10. In other words, in the functional description of the inspection unit 10 in the present embodiment, the projected image 60P may be considered to coincide with the projected image 60. Therefore, the projected image 60P will not be particularly touched below, and will be described using the projected image 60.

With reference to FIGS. 1 and 4, the projection device 40 can project the projected image 60 onto the target surface 80S so as to shift along the shift direction. Specifically, in the present embodiment, the object 80 is placed on the inspection table 12 and is stationary with respect to the projection device 40. The projection device 40 of the present embodiment shifts the brightness distribution of the light emitted by the light emitting element (not shown) along the shift direction, so that the projected image 60 is relative to the stationary target surface 80S. It can be projected so as to shift along the shift direction. However, the present invention is not limited to this. For example, when the projected image 60 can be projected to all the positions on the target surface 80S even if the positional relationship between the object 80 and the projection device 40 changes, more specifically, the target surface 80S is flat. The object 80 may move at a constant speed along the shift direction relative to the projection device 40 when extending to. In this case, the projection device 40 continues to project the same projected image 60 onto the target surface 80S so that the projected image 60 is shifted along the shift direction relative to the moving target surface 80S. Can be projected.

Referring to FIGS. 1 and 3, in the present embodiment, the shift direction coincides with the lateral direction of the projected image 60. However, the present invention is not limited to this, and the shift direction may intersect with the lateral direction of the projected image 60. That is, the shift direction may be oblique to the lateral direction. When the shift direction is oblique to the lateral direction, the bright portion width LW of the projected image 60 is the size of the bright portion 62 in the shift direction, and the dark portion width BW of the projected image 60 is the size of the dark portion 64 in the shift direction. Is.

Referring to FIGS. 1 and 4, the photographing device 50 of the present embodiment is a general-purpose CCD (charge-coupled device) camera, and includes a lens and a large number of light receiving elements arranged two-dimensionally. .. That is, the captured image 70 captured by the photographing device 50 is a digital image composed of a large number of pixels arranged two-dimensionally. The pixels of the captured image 70 according to the present embodiment take a grayscale value from 0 (black) to 255 (white). In other words, the photographing device 50 captures a grayscale image of 256 gradations. However, the present invention is not limited to this, and the photographing device 50 may capture a full-color photographed image 70. However, as will be described later, the inspection unit 10 detects defects by referring to the brightness of the captured image 70. Therefore, from the viewpoint of detecting defects in a short time, a grayscale image in which the brightness can be easily referred to is preferable.

The photographing device 50 of the present embodiment can adjust the position and orientation of the lens. The photographing device 50 is arranged so that the target surface 80S fits within the angle of view of the lens. In other words, the target surface 80S in the present embodiment is a range of the surface of the object 80 that fits within the angle of view of the photographing apparatus 50. The photographing device 50 arranged as described above can photograph the target surface 80S on which the projected image 60 is projected as the photographed image 70. In the captured image 70, the brightness of the projected image 60 is converted to the corresponding grayscale value. In the following description, the brightness in each pixel of the captured image 70 means a grayscale value in each pixel of the captured image 70.

Referring to FIG. 4, the photographing apparatus 50 photographs a part of the projected image 60 along the direction obliquely intersecting with the surface on which the object 80 is placed. Therefore, in general, the aspect ratio of the captured image 70 captured by the photographing device 50 is different from the aspect ratio of the projected image 60, and the captured image 70 is partially distorted with respect to the projected image 60. That is, the captured image 70 does not completely match the projected image 60. However, the inspection unit 10 of the present embodiment can detect defects in the same manner even if the captured image 70 matches the projected image 60 or is different from the projected image 60.

Referring to FIGS. 1 and 2, the processing device 20 according to the present embodiment is a general-purpose PC (Personal Computer), and includes a device main body 22, a storage device 24, an input device 26, and a display device 28. I have.

The device main body 22 is a main body of a PC, and includes a CPU (Central Processing Unit) and a main storage device (not shown). The storage device 24 is, for example, a magnetic disk device, and can store various files (not shown) including an executable file of a program. The storage device 24 acquires, stores, and the like files according to instructions from the device main body 22. In particular, the CPU of the device main body 22 realizes various functions by acquiring an executable file stored in the storage device 24, loading it into the main storage device, and executing a command word in the executable file. The input device 26 is, for example, a keyboard or a mouse, and transmits characters input from the keyboard or a position or range indicated by the mouse to the device main body 22. The display device 28 is, for example, a liquid crystal display, and displays characters, images, and the like transmitted from the device main body 22.

The processing device 20 includes a program (described later) for controlling the projection device 40 and the photographing device 50, and is communicatively connected to each of the projection device 40 and the photographing device 50. The control device 30 is a dedicated device for complementing the control of the projection device 40 and the photographing device 50 by the processing device 20, and the processing device 20 is a cable to each of the projection device 40 and the photographing device 50 via the control device 30. It is connected and is directly connected to the photographing device 50 by a cable. However, the present invention is not limited to this. For example, the control device 30 may be a control board incorporated in the processing device 20. In this case, the processing device 20 may be directly connected to each of the projection device 40 and the photographing device 50 by a cable, or may be wirelessly connected. Further, the projection device 40 and the photographing device 50 may be incorporated in the processing device 20. In this case, the processing device 20 may be connected to each of the projection device 40 and the photographing device 50 by an internal bus.

Referring to FIGS. 2 and 4, the inspection unit 10 configured as described above has a projection function of projecting a projected image 60 onto the target surface 80S by the projection device 40 (see (1) to (3) of FIG. 2). It also has a photographing function (see (1), (4) to (6) of FIG. 2) in which the target surface 80S is photographed by the photographing device 50 and the photographed image 70 is acquired by this image.

Specifically, the processing device 20 of the present embodiment gives a projection and photographing instruction to the control device 30 (see (1) of FIG. 2). At this time, the processing device 20 transmits the inspection parameter to the control device 30. Inspection parameters include projection parameters and imaging parameters. The projection parameters are parameters for creating the projected image 60 projected by the projection device 40, and are, for example, a bright part width LW (for example, 10 pixels), a dark part width BW (for example, 10 pixels), and a leftmost bright part 62. It is a lateral start position (for example, 0 pixel position) of (bright portion 62L in FIG. 3). The shooting parameter is a parameter that defines the brightness of the shot image 70, and is, for example, the exposure time and sensitivity of the shooting device 50.

According to the projection function of the present embodiment, the control device 30 creates a digital image corresponding to the projected image 60 based on the projection parameters. Next, the control device 30 gives a projection instruction to the projection device 40 (see (2) in FIG. 2). At this time, the control device 30 transmits the created digital image to the projection device 40. The projection device 40 emits a projected image 60 based on the received digital image and projects it onto the target surface 80S (see (3) in FIG. 2).

According to the photographing function of the present embodiment, the control device 30 instructs the photographing device 50 to take a picture when a predetermined time elapses from the transmission of the digital image to the projection device 40 until the projected image 60 is projected. (See (4) in FIG. 2). At this time, the control device 30 transmits the photographing parameters received from the processing device 20 to the photographing device 50. Upon receiving the photographing instruction, the photographing apparatus 50 photographs the target surface 80S according to the photographing parameters, thereby acquiring the photographed image 70 (see (5) of FIG. 2). Next, the photographing device 50 transmits the captured image 70 to the processing device 20 (see (6) in FIG. 2). For example, the processing device 20 displays the received captured image 70 on the display device 28.

The processing device 20 of the present embodiment performs the above-mentioned processing (see (1) to (6) of FIG. 2) as many times as necessary while shifting the projected image 60 along the shift direction, whereby 2 or more. The captured image 70 of the above is acquired. Specifically, the processing device 20 performs the above-mentioned processing (see (1) to (6) in FIG. 2), changes the projection parameter, and transmits the message to the control device 30 (see (1) in FIG. 2). ). The projection parameter at this time is, for example, the start position of the bright portion 62L shifted in the lateral direction (shift direction). As a result, the photographing device 50 acquires the photographed image 70 shifted in the shift direction and transmits it to the processing device 20 (see (6) in FIG. 2).

The inspection unit 10 in the present embodiment has the above-mentioned functions. However, the present invention is not limited to this. For example, as long as the control device 30 can create a digital image corresponding to the projection image 60, the contents of the projection parameters are not particularly limited. Similarly, the content of the shooting parameters is not particularly limited. In addition, inspection parameters including projection parameters and imaging parameters can be transmitted at various timings. For example, the processing device 20 may transmit inspection parameters based on an operator's instruction input from the input device 26, or may transmit the inspection parameters at a predetermined predetermined timing. Further, the value of the inspection parameter may be input by the operator by the input device 26 each time the transmission is performed, or may be stored in the storage device 24 in advance.

As described above, according to the present embodiment, the processing device 20 projects the projected image 60 based on the digital image created by the control device 30 by the projection device 40, and the imaging device 20 via the control device 30. The captured image 70 is captured by 50. However, in the following, for the sake of simplicity, the control device 30 and the digital image will not be particularly mentioned.

The inspection unit 10 can execute the inspection process and the inspection preparation process. Specifically, the storage device 24 of the processing device 20 stores an inspection processing program 202 for performing the inspection processing and an inspection preparation processing program 204 for performing the inspection preparation processing. The processing device 20 loads the inspection processing program 202 or the inspection preparation processing program 204 into the main storage device (not shown) in response to an instruction input from the input device 26, and inspects the processing device 20 by the CPU (not shown). Perform processing or inspection preparation processing. As described above, the inspection unit 10 includes programs (inspection processing program 202 and inspection preparation processing program 204) for causing the computer to function as the processing device 20 in the inspection unit 10. These programs are installed in the storage device 24 from a storage medium such as a CD-ROM (compact disk read only memory) in which the programs are stored.

Hereinafter, the inspection process will be described with the processing device 20 as the main body of the processing. However, the following description is also valid with the inspection unit 10 as the main body of processing.

Referring to FIGS. 5 and 6 together with FIG. 2, the processing device 20 performs inspection processing when, for example, the “inspection start” button (not shown) displayed on the display device 28 is clicked by the input device 26. To start. When the processing device 20 starts the inspection process, the processing device 20 first projects the projected image 60 onto the target surface 80S by the projection device 40 (S0510). Next, the processing device 20 captures the target surface 80S by the photographing device 50 and receives the captured image 70 (S0512). As a result, for example, the first photographed image (photographed image) 702 is acquired.

Next, the processing device 20 determines whether or not the bright portion 62 and the dark portion 64 have been projected on all the positions of the target surface 80S (S0514). For example, the processing device 20 displays the captured image 70 on the display device 28, and acquires the area occupied by the target surface 80S in the captured image 70 according to the range specified by using the input device 26. The processing device 20 determines whether or not the bright portion 62 and the dark portion 64 have been projected on the entire acquired region. When the target surface 80S has a position where the bright portion 62 or the dark portion 64 is not projected (NO in S0514), the processing device 20 shifts the projected image 60 in the shift direction. For example, the processing device 20 shifts the projected image 60 in the shift direction by the number of pixels equal to or less than the bright area width LW and the dark area width BW, and re-projects the projected image 60 onto the target surface 80S by the projection device 40 (S0510).

When the bright portion 62 and the dark portion 64 have been projected on all the positions of the target surface 80S (YES in S0514), the processing device 20 creates the MAX image 70X and the MIN image 70N from the acquired plurality of captured images 70. (S0520). For example, the captured image 70 shown in FIG. 6 includes a second captured image (photographed image) 704 and a third captured image (photographed image) 706 in addition to the first captured image 702. In this case, the MAX image 70X and the MIN image 70N are created from the three captured images 70 of the captured images 702, 704 and 706. The MAX image 70X is an image in which the maximum brightness of the same position in the acquired plurality of captured images 70 is set as the brightness at each position. The MIN image 70N is an image in which the minimum brightness at the same position in the acquired plurality of captured images 70 is set as the brightness at each position.

Next, the processing device 20 creates an SSMM (slit shift min max) image 70S from the MAX image 70X and the MIN image 70N (S0522), and detects defects from the created SSMM image 70S (S0524). The SSMM image 70S is an image in which the difference (absolute value) between the brightness at the same position in the MAX image 70X and the brightness at the same position in the MIN image 70N is set as the brightness at each position.

The unevenness on the target surface 80S such as the portion where the defect is formed is highlighted in the SSMM image 70S. For example, the defect portion 82 in which a defect having irregularities such as bumps and dents is formed has the same brightness (gray) in both the MAX image 70X and the MIN image 70N. The defect portion 84 in which the defect due to the sharp scratch is formed has high brightness (color close to white) in both the MAX image 70X and the MIN image 70N. The defect portion 86 in which the defect due to dust or dirt is formed has low brightness (color close to black) in both the MAX image 70X and the MIN image 70N. On the other hand, the portion where the defect is not formed has high brightness (color close to white) in the MAX image 70X and low brightness (color close to black) in the MIN image 70N.

As can be understood from the above description, in the SSMM image 70S, the brightness of the portion corresponding to various types of defects is close to 0, and the brightness of the portion without defects is close to 255. Therefore, in the SSMM image 70S, a defect can be detected by detecting a portion whose brightness is lower than a predetermined value (for example, 128).

Next, the processing device 20 displays the detected defect on the display device 28. For example, the processing device 20 displays the screen shown in FIG. 7. According to the display screen of FIG. 7, the numbers assigned to the defective portions 82, 84, 86 (defect numbers) and the pixel positions (horizontal) in the horizontal direction of the center of gravity of the defective portions 82, 84, 86 with reference to the left end of the SSMM image 70S. Position), the pixel position (vertical position) in the vertical direction of the center of gravity of the defective portion 82, 84, 86 and the number of pixels (size) occupied by the defective portion 82, 84, 86 in the SSMM image 70S with reference to the lower end of the SSMM image 70S. Is displayed. However, when the captured image 70 is displayed on the display device 28, the display screen may be any screen as long as the operator can identify the defect of the target surface 80S.

Referring to FIG. 3, when a virtual straight line 60L extending along the horizontal direction (shift direction) is drawn on the projected image 60, the virtual straight line 60L is formed regardless of the position of the virtual straight line 60L in the vertical direction orthogonal to the horizontal direction. It passes through the bright part 62 and the dark part 64 alternately. Referring to FIG. 4, since the bright portion 62 and the dark portion 64 are arranged as described above, the inspection unit 10 shifts the projected image 60 one or more times along the shift direction by the projection device 40 in the inspection process. By projecting onto the target surface 80S in this way, the bright portion 62 and the dark portion 64 can be projected at all positions on the target surface 80S. Further, the inspection unit 10 photographs the target surface 80S by the photographing device 50 each time the projected image 60 is shifted in the inspection process, so that the bright portion 62 is projected at all the positions on the target surface 80S. An image and an image when the dark portion 64 is projected can be acquired, and defects can be detected from the acquired image.

The inspection process described above can be variously modified as described below.

With reference to FIGS. 3, 8 and 9, how the bright and dark areas 64 of the projected image 60 are arranged as long as the bright and dark areas 64 can be projected at all positions on the target surface 80S. May be good. For example, instead of the projected image 60, each of the projected images 60A, 60B, 60C, and 60D can be used.

Referring to FIG. 8A, the projected image 60A has one bright portion 62 and one dark portion 64. Referring to FIG. 8B, in the projected image 60B, the bright portion widths LW1, LW2, LW3 of the plurality of bright portions 62 are different from each other, and the dark portion widths BW1, BW2 of the plurality of dark portions 64 are different from each other. There is. Referring to FIG. 9A, the projected image 60C is a pattern image in which the bright portion 62 and the dark portion 64 are periodically arranged in the lateral direction, similarly to the projected image 60 (see FIG. 3). However, in the projected image 60C, each of the bright portion 62 and the dark portion 64 extends in a zigzag manner along the vertical direction. Referring to FIG. 9B, in the projected image 60D, a plurality of dark portions 64 having a circular shape are periodically arranged in the horizontal direction and the vertical direction with one bright portion 62 as a background. In the projected image 60D, the dark portion width BW is the diameter of the dark portion 64, and the bright portion width LW is the same position in the vertical direction and in the horizontal direction between two adjacent dark portions 64 in the horizontal direction (shift direction). The distance (shortest distance).

With reference to FIGS. 8 and 9, in any of the modified examples, when a virtual straight line 60L extending along the horizontal direction (shift direction) is drawn on the projected images 60A, 60B, 60C, 60D, the vertical direction is orthogonal to the horizontal direction. Regardless of the position of the virtual straight line 60L in the direction, the virtual straight line 60L alternately passes through the bright portion 62 and the dark portion 64. According to the arrangement of the bright portion 62 and the dark portion 64, the projected images 60A, 60B, 60C, and 60D are projected onto the target surface 80S (see FIG. 4) so as to shift one or more times along the shift direction. Therefore, the bright portion 62 and the dark portion 64 can be projected at all positions on the target surface 80S.

With reference to FIG. 4, the shifting method of the projected image 60 is not particularly limited as long as the bright portion 62 and the dark portion 64 can be projected at all the positions on the target surface 80S. For example, the projected image 60 may be shifted twice or more in the same direction along the shift direction. On the other hand, the projected image 60 may be shifted alternately in the shift direction, such as shifting in one direction along the shift direction and then shifting in the opposite direction. Further, the projected image 60 may project the bright portion 62 and the dark portion 64 only once or twice or more with respect to all the positions on the target surface 80S. However, from the viewpoint of shortening the time required for projecting the projected image 60, the bright portion 62 and the dark portion 64 of the projected image 60 are shifted in the same direction along the shift direction by the same number of pixels one or more times. It is preferable to project the bright portion 62 and the dark portion 64 the minimum number of times for all the positions on the target surface 80S.

According to this embodiment, the defect is detected by directly referring to the SSMM image 70S. However, the present invention is not limited to this, and defects may be detected by indirectly referring to the SSMM image 70S. For example, a binarized image (not shown) obtained by binarizing the SSMM image 70S may be created, and a defect may be detected by referring to the binarized image. Further, the SSMM image 70S may be filtered by a median filter or the like, and the obtained image may be used to detect defects.

As can be understood from the above description, according to the inspection process of the present embodiment, the bright part width LW and the dark part width BW should be set without any particular limitation except for the area of the target surface 80S and the area of the defect to be detected. Is. However, when the inspection process is actually performed, the light-dark ratio (dark part width BW: bright part width LW), which is the ratio between the bright part width LW and the dark part width BW, has a great influence on the defect detection accuracy. That is, it is necessary to change the light-dark ratio according to the state of the target surface 80S. For example, even if the defect can be sufficiently detected by a predetermined light-dark ratio when the color of the target surface 80S is black, the defect cannot be sufficiently detected by the same light-dark ratio when the color of the target surface 80S is white. .. The reason for this is considered as follows.

Referring to FIG. 10, in reality, the brightness of the dark portion 64 gradually decreases from the portion adjacent to the bright portion 62 to the portion (intermediate portion) located between the two bright portions 62. Therefore, when the dark portion width BW is larger than the bright portion width LW (see the graph on the right side of FIG. 10), the brightness of the intermediate portion of the dark portion 64 tends to decrease, while the dark portion width BW is larger than the bright portion width LW. When it is small (see the graph on the left side of FIG. 10), the brightness of the intermediate portion of the dark portion 64 is unlikely to decrease. That is, when the light-dark ratio is small, the difference (contrast) between the brightness of the bright portion 62 and the brightness of the dark portion 64 decreases, and the SSMM image 70S (see FIG. 6) becomes a dark image as a whole. As a result, in the SSMM image 70S, the difference between the brightness of the portion where the defect is formed and the brightness of the portion where the defect is not formed becomes small, which lowers the defect detection accuracy.

According to the above consideration, it is preferable that the dark portion width BW is larger than the bright portion width LW. However, if the dark portion width BW is too large, it becomes difficult to detect defects due to gentle unevenness. That is, the light-dark ratio does not have to be simply large, but an appropriate value of the light-dark ratio exists. Based on the above findings, the inventor of the present application conducted experiments by changing the light-dark ratio in various ways. As a result, the inventor of the present application fixed the bright portion width LW to a constant value (for example, 10 pixels) and changed the dark portion width BW to obtain various defects of various target surfaces 80S (see FIG. 6). We found that it can be detected with high accuracy. More specifically, referring to FIG. 11, it has been found that an appropriate light-dark ratio can be obtained by adjusting the dark part width BW according to the state of the target surface 80S while using a constant bright part width LWP. Further, by projecting the bright portion 62 and the dark portion 64 onto the predetermined position 88 of the target surface 80S (for example, one point on the target surface 80S) and taking a picture, an appropriate dark part width is taken based on the shooting result of the predetermined position 88. It was found that BW can be obtained.

The inventor of the present application has found an inspection preparatory process for obtaining an appropriate dark area width BW through the above considerations and experiments. Hereinafter, the inspection preparation process will be described with the processing device 20 as the main body of the processing. However, the following description is also valid with the inspection unit 10 as the main body of processing.

Referring to FIG. 12 together with FIG. 11, the processing device 20 starts the inspection preparation process when, for example, the “automatic adjustment” button displayed on the display device 28 is clicked by the input device 26. When the processing device 20 starts the inspection preparation process, it first acquires the gazing point (predetermined position 78) (S1210).

The predetermined position 78 is a position on the captured image 70 and corresponds to the predetermined position 88 of the projected image 60. Specifically, for example, the processing device 20 photographs the target surface 80S on which the projected image 60 is projected by the photographing device 50, and displays the acquired photographed image 70 on the display device 28. The processing device 20 acquires a position designated by the operator using the input device 26 as a predetermined position 78. The predetermined position 78 is, for example, a position (pixel value) in the horizontal direction and the vertical direction with respect to the lower left of the captured image 70. The predetermined position 78 may be a point of 1 pixel or an area composed of a plurality of pixels. For example, the predetermined position 78 may include a plurality of pixels located within a circle having a radius of several pixels centered on a designated point of one pixel.

The processing device 20 of the present embodiment can acquire the predetermined position 78 as described above. However, the present invention is not limited to this, and the processing device 20 may acquire a predetermined position 78 without being directly designated by the operator. For example, the processing device 20 may acquire the area occupied by the target surface 80S in the captured image 70 by specifying the range input from the input device 26. In this case, the processing device 20 may set an intermediate position in the horizontal direction and the vertical direction of the acquired region as a predetermined position 78. Further, the processing device 20 may set an intermediate position in the horizontal direction and the vertical direction of the entire captured image 70 as a predetermined position 78 regardless of the input from the input device 26.

Next, the processing device 20 acquires one of L (L is an integer of 1 or more) predetermined bright part width LWP (S1212). The bright part width LWP is, for example, 10 pixels. For the bright part width LWP, for example, a value based on past inspection results may be stored in advance in the bright part width file 242 of the storage device 24. In this case, L is the number of bright part width LWP stored in the bright part width file 242. On the other hand, the bright portion width LWP may be specified by the operator, for example. In this case, L is the number of bright part width LWP specified by the operator. Next, the processing device 20 performs a shooting preparation process and a projection preparation process (S1214). Specifically, the processing device 20 projects a projected image 60 having a bright portion width LWP at a predetermined position 78 while changing the dark portion width BW, and shoots the projected image 60 while changing the exposure time and the sensitivity. The inspection parameters including the appropriate dark area width BWD, exposure time, and sensitivity corresponding to the area width LWP are acquired (S1214).

Next, the processing device 20 determines whether or not the above-mentioned inspection parameter acquisition processing (processing of S121 to S1214) has been executed L times (S1216). When the inspection parameter acquisition process is not executed L times (NO in S1216), the processing device 20 acquires the next one of the L bright part width LWPs (S1212). As understood from the above description, the processing device 20 acquires one set of inspection parameters each time the inspection parameter acquisition process is executed.

When the processing device 20 has executed the inspection parameter acquisition process (processing of S121 to S1214) L times (YES in S1216), the processing device 20 corresponds to the acquired inspection parameter of the L set with the captured image 70 according to the inspection parameter. Attach and create a selection screen (S1220). Next, the processing device 20 displays the created selection screen on the display device 28 and prompts the selection of the inspection parameter (S1222). An example of the selection screen is shown in FIG. The operator corresponds to the captured image 70 by, for example, using the input device 26, clicking the inspection parameter selection button displaying the more preferable captured image 70, and then clicking the selection end button. Inspection parameters can be selected. On the other hand, the operator can not select the inspection parameter, for example, by clicking the selection end button without clicking the selection button.

Next, the processing device 20 determines whether or not the operator has selected the inspection parameter (S1224). When the operator does not select the inspection parameter (NO in S1224), the processing device 20 ends the inspection preparation process. On the other hand, when the operator selects the inspection parameter (YES in S1224), the processing device 20 stores the inspection parameter selected by the operator in the inspection parameter file 246 of the storage device 24 (S1226). Next, the processing device 20 displays a screen (not shown) for selecting whether or not to execute the inspection process on the display device 28, and waits for the operator's selection (S1230). When the operator chooses not to execute the inspection process (NO in S1230), the processing device 20 ends the inspection preparation process.

In the present embodiment, when the operator chooses to perform the inspection process (YES in S1230), the processing device 20 uses any of the inspection parameters selected by the operator to describe the above. The inspection process (see FIG. 5) is performed. For example, when the operator selects one inspection parameter in the inspection preparation process (S1224), the inspection parameter selected by the operator may be used as the inspection parameter in the inspection process. On the other hand, when the operator selects two or more inspection parameters, the operator may be prompted to select the inspection parameters to be used in the inspection process.

In the present embodiment, the inspection process is executed following the inspection preparation process. However, the present invention is not limited to this. For example, the inspection process and the inspection preparation process may be independent processes. In this case, the processing device 20 may end the inspection preparation process without waiting for the operator's selection (S1230). Further, the processing device 20 may allow the operator to select one of the inspection parameters in the inspection parameter file 246 of the storage device 24 when the processing is started in the inspection processing (see FIG. 5). In this case, the operator may select the inspection parameter using an operating device (not shown) communicatively connected to the processing device 20. More specifically, when the inspection unit 10 is installed in the factory, the equipment management equipment of the factory has characteristics such as the paint color of the object 80 conveyed to the inspection unit 10 by a belt conveyor (not shown). The inspection parameters may be switched according to the above.

Hereinafter, the imaging preparation process and the projection preparation process (S1214) in the inspection preparation process (see FIG. 12) will be described in more detail.

Referring to FIG. 14 together with FIG. 11, the processing apparatus 20 performs the first imaging preparation process (S1410) before the projection preparation process (S1412). The first process for preparing for shooting is a process for adjusting the brightness of the entire captured image 70. More specifically, the processing device 20 can adjust the brightness of the entire captured image 70 by designating a photographing parameter that defines the brightness of the photographing device 50 when instructing the photographing device 50 to shoot. In the first process of preparing for shooting, the processing device 20 performs the first process of adjusting the shooting parameters one or more times while changing the shooting parameters, and acquires a temporary setting value of the shooting parameters (S1410). As will be described later, the processing device 20 performs the projection preparation process using the temporarily set values acquired in this way.

As described above, the imaging parameters of the present embodiment are the exposure time and sensitivity of the light receiving element (not shown) of the imaging device 50. In the present embodiment, the exposure time can be specified by a plurality of steps in the range of 1000 μs to 15000 μs. On the other hand, the sensitivity can be specified by a plurality of steps of analog gain in the range of −6.0 dB to +18 dB. However, the present invention is not limited to this. For example, the settable range of exposure time and sensitivity and the number of steps are not particularly limited. Further, the shooting parameters are not limited to the exposure time and the sensitivity. For example, the imaging parameters may include the aperture of the lens (not shown) of the imaging apparatus 50 in addition to the exposure time and sensitivity.

In the present embodiment, the processing apparatus 20 performs the first imaging preparation process (S1410) for each of the exposure time and the sensitivity. For example, the processing device 20 performs the first exposure preparation process (S1410) for the exposure time to obtain a temporary setting value of the exposure time, and then performs the first shooting preparation process (S1410) for the sensitivity to temporarily set the sensitivity. Get the value.

Referring to FIG. 15 together with FIG. 11, the processing device 20 is determined by the projection device 40 in each of the shooting parameter adjustment first processing (shooting parameter adjustment processing) of the shooting preparation first processing (S1410 in FIG. 14). Each of the bright portion 62 and the dark portion 64 is projected once or more with respect to the predetermined position 88 corresponding to the position 78, and the predetermined position 88 is photographed by the photographing device 50 (S1510). Specifically, the projected image 60 is projected onto the target surface 80S while shifting along the shift direction, and each time the projected image 60 is shifted, the target surface 80S is photographed to acquire the captured image 70. Regardless of the position of the predetermined position 88 on the surface 80S, the captured image 70 when the bright portion 62 is projected on the predetermined position 88 and the captured image 70 when the dark portion 64 is projected on the predetermined position 88 can be acquired. .. That is, two or more captured images 70 can be captured.

In the above process (S1510), the bright part width LW of the projected image 60 may be, for example, the bright part width LWP stored in the bright part width file 242 as described above. On the other hand, the dark portion width BW of the projected image 60 may be a size equal to or larger than the bright portion width LWP (for example, 10 pixels). Further, when trying to acquire the provisionally set value of the exposure time, the sensitivity of the photographing apparatus 50 may be a standard sensitivity (for example, analog gain 0 dB). On the other hand, when trying to acquire the temporary setting value of the sensitivity, the temporary setting value of the acquired exposure time may be used for the exposure time of the photographing device 50.

Next, the processing device 20 acquires the maximum brightness, which is the maximum value of the brightness at the predetermined position 78, by the two or more captured images 70 captured by the photographing device 50 (S1512). At this time, the maximum brightness at the predetermined position 78 can be obtained by creating the MAX image 70X (see FIG. 6) from the two or more captured images 70. When the predetermined position 78 is composed of a plurality of pixels, for example, the simple average value of the luminance at the plurality of pixels may be the luminance at the predetermined position 78.

The processing device 20 repeats the above-mentioned shooting parameter adjustment processing (S1510, S1512) as many times as necessary (N times) while changing the shooting parameters of the shooting device 50, and based on the acquired maximum brightness of N pieces. Acquire a value (setting candidate value) to be set as a shooting parameter (S1514).

For example, when the processing device 20 is trying to acquire the provisionally set value of the exposure time, the processing device 20 may repeat the shooting parameter adjustment processing (S1510, S1512) while changing the exposure time from the minimum value to the maximum value step by step. .. Similarly, when trying to acquire the temporary setting value of the sensitivity, the shooting parameter adjustment process may be repeated while changing the analog gain from the minimum value to the maximum value step by step. According to this process, the shooting parameter when the highest value of the acquired maximum luminance is obtained may be set as a setting candidate value.

On the other hand, in order to shorten the processing time, the target value (target brightness) of the maximum brightness and the tolerance may be set in advance. The target brightness is such that the noise of the captured image 70 can be reduced and the bright portion 62 and the dark portion 64 can be clearly distinguished. The target brightness may be, for example, about 160 to 230. The tolerance error may be a value larger than the measurement error, and may be, for example, about 5 to 15. In this case, if the maximum brightness acquired in the shooting parameter adjustment processing (S1510, S1512) is within the allowable error range with respect to the target brightness, the processing device 20 sets the shooting parameter at this time as a setting candidate value. Just do it. According to this process, a setting candidate value may be obtained in the first shooting parameter adjustment process. Therefore, the photographing parameter adjustment process may be repeated once or more.

Referring to FIG. 14 together with FIG. 11, as described above, the processing device 20 takes a picture based on the maximum brightness of 1 or more acquired by the first process of adjusting the shooting parameters in the first process of preparing for shooting (S1410). You can get the temporary setting value of the parameter. At this time, the temporary setting value of the exposure time may be first acquired, and then the temporary setting value of the sensitivity may be acquired by using the temporary setting value of the exposure time. However, the present invention is not limited to this. For example, the acquisition order of the temporary set value of the exposure time and the temporary set value of the sensitivity may be reversed. Both the tentative set value of the exposure time and the tentative set value of the sensitivity may be acquired at the same time in one shooting preparation first process. Further, in addition to the temporary setting value of the sensitivity and the temporary setting value of the exposure time, another shooting parameter (for example, the temporary setting value of the aperture) may be acquired.

Next, the processing device 20 performs the projection preparation process (S1412). The projection preparation process is a process of adjusting the contrast of the entire captured image 70. In the projection preparation process, the processing device 20 performs one or more dark part width adjustment processes while changing the dark part width BW by using the temporary setting values of the shooting parameters acquired in the first shooting preparation process (S1410). , Acquire the dark area width BWD in the inspection process.

Referring to FIG. 16 together with FIG. 11, in each of the dark portion width adjusting processes of the projection preparation process (S1412 of FIG. 14), the processing device 20 uses the projection device 40 with respect to the predetermined position 88 corresponding to the predetermined position 78. Then, each of the bright portion 62 and the dark portion 64 is projected one or more times, and the predetermined position 88 is photographed by the photographing device 50 (S1610). Specifically, the projected image 60 is projected onto the target surface 80S while shifting along the shift direction, and each time the projected image 60 is shifted, the target surface 80S is photographed to acquire the captured image 70. Regardless of the position of the predetermined position 88 on the surface 80S, the captured image 70 when the bright portion 62 is projected on the predetermined position 88 and the captured image 70 when the dark portion 64 is projected on the predetermined position 88 can be captured. .. That is, two or more captured images 70 can be captured.

In the above process (S1610), the bright part width LW of the projected image 60 may be the bright part width LWP in the first process of preparing for shooting (S1410 of FIG. 14). The initial value of the dark portion width BW (value used in the first S1610) may be the dark portion width BW in the first process of preparing for shooting. Further, as the exposure time and sensitivity of the photographing apparatus 50, the provisionally set values of the exposure time and sensitivity acquired by the first process of preparing for photographing may be used. That is, in the projection preparation process, the processing device 20 may take a picture by the photographing device 50 using the provisionally set value of the photographing parameter.

Next, the processing device 20 acquires the contrast, which is the difference between the maximum value of the luminance and the minimum value of the luminance at the predetermined position 78, by the two or more captured images 70 captured by the photographing device 50 (S1612). At this time, the contrast at the predetermined position 78 can be obtained by creating the SSMM image 70S (see FIG. 6) from the two or more captured images 70. When the predetermined position 78 is composed of a plurality of pixels, for example, a simple average value of the contrasts in the plurality of pixels may be used as the contrast of the predetermined position 78.

The processing device 20 repeats the above-mentioned dark portion width adjustment processing (S1610, S1612) as many times as necessary (M times) while changing the dark portion width BW of the projected image 60, based on the acquired M contrasts. The dark area width BWD in the inspection process is acquired (S1614).

For example, the processing device 20 may repeat the dark portion width adjustment processing (S1610, S1612) while changing the dark portion width BW from the bright portion width LWP to the width of the entire projected image 60 by one pixel. According to this process, the dark area width BW when the highest value of the acquired contrast is obtained may be set as the dark area width BWD in the inspection process.

On the other hand, in order to shorten the processing time, the target value (target contrast) of the contrast and the tolerance may be set in advance. The target contrast is high enough to clearly identify defects in the SSMM image 70S (see FIG. 6). The target contrast may be, for example, about 140 to 200. The tolerance error may be a value larger than the measurement error, and may be, for example, about 5 to 15. In this case, if the acquired contrast is within the allowable error with respect to the target contrast in the dark portion width adjusting process (S1610, S1612), the processing device 20 uses the dark portion width BW at this time as the dark portion width in the inspection process. It may be BWD. According to this process, the dark area width BWD in the inspection process may be obtained in the first dark area width adjusting process. Therefore, the dark portion width adjusting process may be repeated once or more.

Referring to FIG. 14 together with FIG. 11, as described above, in the projection preparation process (S1412), the processing apparatus 20 has a dark area width BWD in the inspection process based on one or more contrasts acquired by the dark area width adjustment process. Can be obtained.

The projection preparation process (S1412) affects the brightness of the entire captured image 70. Therefore, the processing device 20 performs the shooting preparation second processing (S1414) after the projection preparation processing, and adjusts the brightness of the entire captured image 70 that has changed due to the influence of the projection preparation processing. In the second process of preparing for shooting, the processing device 20 performs the second process of adjusting the shooting parameters one or more times while changing the shooting parameters, and acquires the set value of the shooting parameters in the inspection process (S1414).

Referring to FIG. 15 together with FIG. 11, the second shooting preparation process (shooting preparation process) is basically the same as the first shooting preparation process described above. That is, in the second processing (S1510, S1512) for adjusting the imaging parameters, the processing device 20 uses the projection device 40 to set the bright portion 62 and the dark portion 64 to the predetermined position 88 corresponding to the predetermined position 78, respectively. The maximum brightness, which is the maximum value of the brightness at the predetermined position 78, is acquired by two or more shot images 70 taken by the shooting device 50 by projecting the images more than once (S1510) (S1512). However, the dark portion width BW of the projected image 60 in the second shooting preparation process (S1510) is the dark portion width BWD acquired in the projection preparation process (S1412 in FIG. 14). Further, the processing device 20 acquires the set value of the photographing parameter in the inspection process instead of the temporary set value based on the maximum brightness of 1 or more acquired by the photographing parameter adjusting process (S1514).

Referring to FIG. 14 together with FIG. 11, as described above, the processing apparatus 20 inspects the imaging preparation second process (S1414) based on the maximum brightness of 1 or more acquired by the imaging parameter adjustment second process. The set value of the shooting parameter in the process can be acquired. The second process for preparing for shooting can be variously modified like the first process for preparing for shooting (S1410).

The above-mentioned first shooting preparation process (S1410), projection preparation processing (S1412), and second shooting preparation process (S1414) can be further deformed in addition to the above-described deformations. For example, if the contrast at the predetermined position 78 is already within the allowable error range with respect to the target contrast after the first shooting preparation process is completed and before the projection preparation process is executed, the projection preparation process and the second shooting preparation process are performed. It is not necessary to execute the process. In this case, the first shooting preparation process also functions as the projection preparation process. Further, from the viewpoint of shortening the processing time, each of the shooting preparation first processing and the shooting preparation second processing may be modified as follows.

What needs to be acquired in each of the first process of preparation for shooting and the second process of preparation for shooting is the maximum brightness of the predetermined position 78, and the maximum brightness is one image when the bright portion 62 is projected on the predetermined position 78. It can be obtained only from the captured image 70. That is, instead of shooting the projected image 60 while shifting along the shift direction, if the projected image 60 is projected so that the bright portion 62 is projected at the predetermined position 78 and the projected image 60 is shot once, the predetermined position 78 You can get the maximum brightness of. Therefore, in each of the imaging parameter adjustment first processing and the imaging parameter adjustment second processing, the processing device 20 uses the projection device 40 to perform the bright portion 62 at least once with respect to the predetermined position 88 corresponding to the predetermined position 78. The maximum brightness, which is the maximum value of the brightness at the predetermined position 78, may be obtained by projecting (S1590 in FIG. 15) and taking one or more captured images 70 taken by the photographing device 50 (S1592 in FIG. 15).

With reference to FIG. 11, as described above, in the inspection unit 10 according to the present embodiment, in addition to the inspection process for detecting defects, the projection preparation process and the imaging preparation process (imaging preparation first processing and imaging) The inspection preparation process including the preparation second process) can be executed. In this projection preparation process (inspection preparation process), the inspection unit 10 projects the bright portion 62 and the dark portion 64 one or more times on at least one predetermined position 88 on the target surface 80S by the projection device 40. Two or more captured images 70 are captured by the photographing device 50. As a result, an image when the bright portion 62 is projected (bright image) and an image when the dark portion 64 is projected (dark image) are obtained at the predetermined position 88.

The inspection unit 10 can prepare an appropriate dark portion width BWD in the inspection process based on the bright image and the dark image at the predetermined position 78 corresponding to the predetermined position 88. For example, the inspection unit 10 can prepare the dark portion width BWD based on the contrast which is the difference between the brightness of the bright image and the brightness of the dark image. That is, according to the present embodiment, an appropriate light-dark ratio can be set even by a person who is not skilled in inspection, thereby providing an inspection unit 10 capable of accurately detecting defects.

With reference to FIGS. 11 and 14, the inspection unit 10 according to the present embodiment performs the imaging preparation process before and after the projection preparation process as described above. By performing the imaging preparation process before the projection preparation process to adjust the exposure time and the sensitivity of the imaging apparatus 50, a more appropriate dark portion width BWD can be obtained in the projection preparation process. Further, by performing the imaging preparation process again after the projection preparation process and readjusting the exposure time and the sensitivity of the imaging device 50, it is possible to acquire a captured image 70 having a higher contrast in the inspection process. Defects can be detected more accurately. However, the present invention is not limited to this, and each of the imaging preparation processes before and after the projection preparation process may be executed according to the detection accuracy required for detecting defects.

In addition to the modification already described, the present embodiment can be further modified in various ways as described below.

Referring to FIG. 11, the predetermined position 88 (predetermined position 78) in the present embodiment is one place. However, the predetermined position 88 (predetermined position 78) may be two or more. In this case, as the brightness at the predetermined position 78, for example, a simple average value of the brightness at two or more predetermined positions 78 may be used. Further, in this case, the operator may specify some of the predetermined positions 78, and the processing device 20 may set some of the remaining predetermined positions 78. On the other hand, the operator may specify all of the predetermined positions 78, or the processing device 20 may set all of the predetermined positions 78.

With reference to FIGS. 3, 8 and 9, various images such as the projected images 60A, 60B, 60C and 60D can be used in place of the projected image 60 in the inspection preparation process. For example, when an image having a plurality of bright part widths LW different from each other and a plurality of dark part width BWs different from each other is used as in the projected image 60B, a plurality of bright part width LWs are prepared in advance in the projection preparation process. While a plurality of bright area widths LWP are used, a plurality of dark area widths BW may be changed by the same number of pixels or the same ratio. Further, when an image in which a pattern formed by a plurality of dark areas 64 is formed against a background of one bright area 62 such as the projected image 60D, the dark area width BW is set to the same number of pixels and the same ratio to each other in the projection preparation process. You can change it.

With reference to FIGS. 11 and 15, as described above, the exposure time and sensitivity in the inspection process can be reliably obtained by changing the exposure time and sensitivity step by step in the shooting preparation process. On the other hand, according to this method, the processing time of the shooting preparation process becomes long. From the viewpoint of shortening the processing time of the shooting preparation process, the shooting preparation process may be modified as shown in FIG. The shooting preparation process of FIG. 17 will be described below.

Referring to FIG. 17 together with FIG. 11, first, the processing apparatus 20 sets a predetermined initial value in the photographing parameters (exposure time and sensitivity) (S1710). The initial values of the exposure time and the sensitivity are the standard exposure time and the sensitivity in the photographing apparatus 50, and differ depending on the photographing apparatus 50. The initial value of the exposure time may be, for example, about 1000 μs, and the initial value of the sensitivity may be, for example, about 0 dB. Next, the processing device 20 projects the projected image 60 onto the target surface 80S by the projection device 40, and captures the captured image 70 by the photographing device 50 (S1712). The bright portion 62 of the projected image 60 has the predetermined bright portion width LWP (for example, a value of about 10 to 20 pixels) described above. On the other hand, the dark portion width BW of the projected image 60 may be, for example, about 10 to 20 pixels.

Next, the processing device 20 determines whether or not the bright portion 62 and the dark portion 64 have been projected on all the positions of the target surface 80S (S1714). When the target surface 80S has an unprojected position of the bright portion 62 or the dark portion 64 (NO in S1714), the processing device 20 shifts the projected image 60 along the shift direction (S1716), and then again the target surface. The projected image 60 is projected onto the 80S and photographed (S1712).

When the bright portion 62 and the dark portion 64 have already been projected on all the positions of the target surface 80S (YES in S1714), the processing device 20 uses the two or more captured images 70 captured by the photographing device 50 to obtain the MAX image 70X (the case of YES). (See FIG. 6) is created, thereby acquiring the maximum brightness, which is the maximum value of the brightness at the predetermined position 78 (S1718). Next, the processing device 20 determines whether or not the maximum luminance is acquired for the first time (that is, whether or not the processing of S1718 is performed for the first time) (S1720).

When the processing device 20 acquires the maximum brightness for the first time (YES in S1720), the processing device 20 determines whether or not the acquired maximum brightness is within the range of the preset tolerance with respect to the preset target brightness (when it is acquired, S1722). When the maximum brightness is within the allowable error range with respect to the target brightness (YES in S1722), the processing device 20 ends the processing, and sets the imaging parameters set at this time in the projection preparation processing or the inspection processing. It is used as a shooting parameter (see FIG. 14).

When the maximum brightness is out of the allowable error range with respect to the target brightness (NO in S1722), the processing device 20 corrects the photographing parameter based on the difference between the maximum brightness and the target brightness. More specifically, the longer the exposure time, the higher the maximum brightness, and the higher the sensitivity, the higher the maximum brightness should be. Therefore, the processing device 20 corrects the shooting parameters by, for example, the following shooting parameter correction formula 1 or shooting parameter correction formula 2 to obtain the corrected shooting parameters. The processing device 20 again projects the projected image 60 onto the target surface 80S and photographs the image according to the corrected imaging parameters (S1712).

[Shooting parameter correction formula 1] When the exposure time does not reach the settable maximum value Exposure time after correction = Exposure time before correction + (Target brightness-Maximum brightness) / 2 x α: However, α = Exposure time Settable range (14000) / Number of gradations of captured image 70 (256)
Sensitivity after correction = Sensitivity before correction

[Shooting parameter correction formula 2] When the exposure time reaches the maximum value that can be set. Exposure time after correction = Exposure time before correction Sensitivity after correction = Sensitivity before correction + (Target brightness-Maximum brightness) / 2 × β: However, β = analog gain settable range (24) / number of gradations of captured image 70 (256)

When the processing device 20 performs the maximum luminance acquisition process (S1718) from the second time onward (i-th time) (NO in S1720), whether or not the maximum luminance is acquired is the Nth time (that is,). Whether or not i = N) is determined (S1726). N is a preset maximum number of trials and is an integer of 2 or more. By increasing N, the maximum brightness closer to the target brightness can be obtained, but the processing time becomes longer. Therefore, N may be set according to the detection accuracy required for detecting defects and the required response speed. For example, N may be set to about 5 to 15. When i ≧ N (YES in S1726), the processing device 20 ends the processing and uses the photographing parameter set at this time as the imaging parameter of the projection preparation process or the inspection process (see FIG. 14). ..

When i <N (NO in S1726), the processing device 20 determines whether or not the maximum luminance acquired at the i-th time is within the allowable error with respect to the target luminance (S1728). When the maximum brightness is within the allowable error range with respect to the target brightness (YES in S1728), the processing device 20 ends the processing, and sets the imaging parameters set at this time in the projection preparation processing or the inspection processing. It is used as a shooting parameter (see FIG. 14).

When the maximum brightness of the processing device 20 is out of the allowable error range with respect to the target brightness (NO in S1728), the maximum brightness acquired at the i-th time is the maximum brightness of the previous time (i-1st time). Then, it is determined whether or not it is within the range of the preset minimum value (that is, whether or not the maximum brightness is substantially changed in consideration of the measurement error) (S1730). The minimum value may be a value larger than the measurement error, and may be, for example, about 2 to 8. When the maximum brightness does not substantially change (YES in S1730), the processing device 20 ends the processing and uses the previously set imaging parameter as the imaging parameter of the projection preparation process or the inspection process (when the result is YES in S1730). See FIG. 14).

When the maximum brightness is substantially changed (NO in S1730), the processing device 20 includes the maximum brightness, the maximum brightness of the previous time (i-1st time), the shooting parameters and the target of the previous time (i-1st time). The shooting parameters of this time (ith time) are corrected based on the brightness. More specifically, the processing device 20 corrects the current shooting parameter by, for example, the following shooting parameter correction formula 3 or shooting parameter correction formula 4, and obtains the corrected shooting parameter (i + 1th time). The processing device 20 again projects the projected image 60 onto the target surface 80S and photographs the image according to the corrected imaging parameters (S1712).

[Shooting parameter correction formula 3] When the exposure time has not reached the maximum value that can be set Corrected exposure time = previous (i-1st) exposure time + (current exposure time-previous exposure time) x { (Target brightness-previous maximum brightness) / (current maximum brightness-previous maximum brightness)}
Sensitivity after correction = Sensitivity before correction

[Shooting parameter correction formula 4] When the exposure time reaches the maximum value that can be set. Exposure time after correction = Exposure time of this time (ith time) Sensitivity after correction = Sensitivity of previous time (i-1st time) + ( This time sensitivity-previous sensitivity) x {(target brightness-previous maximum brightness) / (current maximum brightness-previous maximum brightness)}

According to the shooting preparation process of FIG. 17, appropriate shooting parameters can be obtained while shortening the processing time. In particular, the sensitivity can be adjusted while preferentially adjusting the exposure time, which is easier to adjust. However, the above-mentioned shooting preparation processing (particularly, shooting parameter correction formulas 1 to 4) is merely an example, and the shooting preparation process can be variously modified as long as the maximum brightness can be corrected so as to approach the target brightness.

With reference to FIGS. 11 and 16, as described above, the dark area width BWD in the inspection process can be reliably obtained by changing the dark area width BW one pixel at a time in the projection preparation process. On the other hand, according to this method, the processing time of the projection preparation process becomes long. From the viewpoint of shortening the processing time of the projection preparation process, the projection preparation process may be modified as shown in FIG. Hereinafter, the projection preparation process of FIG. 18 will be described.

Referring to FIG. 18 together with FIG. 11, first, the processing apparatus 20 sets an initial value for the dark portion width BW (S1810). Next, the processing device 20 projects the projected image 60 onto the target surface 80S by the projection device 40, and captures the captured image 70 by the photographing device 50 (S1812). The bright portion 62 in the projected image 60 has the same bright portion width LWP as the shooting preparation process. The initial value of the dark portion width BW in the projected image 60 may be the dark portion width BW used in the shooting preparation process. Further, the photographing parameters (exposure time and sensitivity) of the photographing apparatus 50 may be values acquired in the photographing preparation process.

Next, the processing device 20 determines whether or not the bright portion 62 and the dark portion 64 have been projected on all the positions of the target surface 80S (S1814). When the target surface 80S has an unprojected position of the bright portion 62 or the dark portion 64 (NO in S1814), the processing device 20 shifts the projected image 60 along the shift direction (S1816), and then again the target surface. The projected image 60 is projected onto the 80S and photographed (S1812).

When the bright portion 62 and the dark portion 64 have already been projected on all the positions of the target surface 80S (YES in S1814), the processing device 20 uses the two or more captured images 70 captured by the imaging device 50 to obtain the SSMM image 70S ( (See FIG. 6) is created, thereby acquiring the contrast which is the difference between the maximum value and the minimum value of the brightness at the predetermined position 78 (S1818). Next, the processing device 20 determines whether or not the contrast is acquired for the first time (that is, whether or not the processing of S1818 is performed for the first time) (S1820).

When the contrast is acquired for the first time (YES in S1820), the processing device 20 sets a predetermined maximum value in the dark area width BW (S1822), and again projects the projected image 60 onto the target surface 80S to take a picture (S1820). S1712). The predetermined maximum value may be calculated by, for example, the following maximum dark area width calculation formula.

[Maximum dark area width calculation formula]
Maximum value = Bright area width LW × (Number of shots of projected image 60 in the processing of S1812 to S1816-1) / Maximum shift amount = For example, in each shooting of projected image 60, only 1/2 of the bright area width LW is projected image 60. When shifting, bright part width LW × (10-1) / 2

When the processing device 20 performs the contrast acquisition process (S1818) from the second time onward (i-th time) (NO in S1820), whether or not the contrast is acquired at the M-th time (that is, i = Whether or not it is M) is determined (S1824). M is a preset maximum number of trials and is an integer of 2 or more. By increasing M, a contrast that makes it easier to detect defects can be obtained, but the processing time becomes longer. Therefore, M may be set according to the detection accuracy required for detecting defects and the required response speed. For example, M may be set to about 5 to 15. When i ≧ M (YES in S1824), the processing device 20 ends the processing and uses the dark portion width BW set last time (i-1st time) as the dark portion width BWD in the inspection process (the processing device 20 ends the process). See FIG. 14).

When i <N (NO in S1824), the processing device 20 determines whether or not the contrast acquired at the i-th time is within the allowable error with respect to the target contrast (S1826). When the contrast is within the allowable error range with respect to the target contrast (YES in S1826), the processing device 20 ends the processing, and sets the dark portion width BW set at this time as the dark portion width BWD in the inspection process. It is used (see FIG. 14).

When the contrast is out of the allowable error range for the target contrast (NO in S1826), the processing device 20 obtains the contra for the i-th time in advance with respect to the contrast for the previous time (i-1st time). It is determined whether or not it is within the set minimum value range (that is, whether or not the contrast is substantially changed in consideration of the measurement error) (S1828). The minimum value may be a value larger than the measurement error, and may be, for example, about 2 to 8. When the contrast has not substantially changed (YES in S1828), the processing device 20 ends the processing and uses the previously set dark portion width BW as the dark portion width BWD in the inspection process (see FIG. 14). ).

When the contrast is substantially changed (NO in S1828), the processing device 20 adjusts the dark portion width BW by 1/2 of the difference from the previous dark portion width BW so that the contrast becomes high. (S1830). Specifically, the processing device 20 corrects the dark portion width BW this time by the following dark portion width correction formula 1 or dark portion width correction formula 2 (S1830), and again projects the projected image 60 onto the target surface 80S to take a picture (S). S1812).

[Dark area correction formula 1] When the contrast is increased compared to the previous time. Corrected dark area width BW = current dark area width BW + (current dark area width BW-previous dark area width BW) / 2

[Dark area correction formula 2] When the contrast is reduced compared to the previous time The corrected dark area width BW = current dark area width BW- (current dark area width BW-previous dark area width BW) / 2

According to the projection preparation process shown in FIG. 18, an appropriate dark area width BWD can be obtained while shortening the processing time. However, the projection preparation processing described above (particularly, the maximum dark area width calculation formula and the dark area width correction formulas 1 and 2) is merely an example, and the projection preparation process can be performed in various ways as long as the contrast can be corrected so as to approach the target contrast. It is deformable.

10 Inspection unit 12 Inspection table 20 Processing device 202 Inspection processing program 204 Inspection preparation processing program 22 Device main body 24 Storage device 242 Bright area width file 246 Inspection parameter file 26 Input device 28 Display device 30 Control device 40 Projection device 50 Imaging device 60, 60P Projected image 60L Virtual straight line 62, 62L Bright part 64 Dark part 60A, 60B, 60C, 60D (Modified example) Projected image LW, LWP Bright part width BW Dark part width 70 Photographed image 702 First shot image (photographed image)
704 Second shot image (taken image)
706 Third photographed image (photographed image)
70X MAX image 70N MIN image 70S SSMM image 78 Predetermined position 80 Object 80S Target surface 82, 84, 86 Defect part 88 Predetermined position

Claims (6)

An inspection unit for detecting defects on the target surface.
The inspection unit includes a projection device and an imaging device.
The projection device can project the projected image onto the target surface so as to shift along the shift direction.
The photographing device can photograph the target surface, and can photograph the target surface.
The projected image includes one or more bright areas and one or more dark areas having a lower brightness than the bright areas.
By projecting the projected image onto the target surface so as to shift one or more times along the shift direction, the bright portion and the dark portion can be projected at all positions on the target surface.
The inspection unit is capable of performing inspection processing and inspection preparation processing.
In the inspection process, the inspection unit projects the projected image onto the target surface so as to shift the projected image one or more times along the shift direction by the projection device, and photographs the target surface by the imaging device. And thereby detect the defect
In the inspection preparation process, the inspection unit projects the bright part and the dark part one or more times on at least one predetermined position on the target surface by the projection device, and the inspection unit 2 An inspection unit that captures the above images. The inspection unit according to claim 1.
The inspection unit is provided with a processing device.
The processing device is communicatively connected to each of the projection device and the photographing device.
The inspection preparation process includes a projection preparation process.
In the projection preparation process, the processing device performs one or more dark portion width adjustment processes while changing the dark portion width.
In each of the dark portion width adjusting processes, the processing device projects the bright portion and the dark portion one or more times with respect to the predetermined position by the projection device, and two or more images taken by the photographing apparatus. From the image, the contrast which is the difference between the maximum value of the brightness and the minimum value of the brightness at the predetermined position is acquired.
The processing device is an inspection unit that acquires the dark portion width in the inspection process based on one or more contrasts acquired by the dark portion width adjusting process in the projection preparation process. The inspection unit according to claim 2.
In addition to the projection preparation process, the inspection preparation process includes an imaging preparation first process and an imaging preparation second process.
Before the projection preparation process, the processing device performs the shooting preparation first process,
In the first process of preparing for shooting, the processing device performs the first process of adjusting shooting parameters one or more times while changing the shooting parameters that define the brightness of the shooting device.
In each of the first processings for adjusting the imaging parameters, the processing apparatus projects the bright portion at least once with respect to the predetermined position by the projection apparatus, and the imaging apparatus captures one or more images. , Acquires the maximum brightness which is the maximum value of the brightness at the predetermined position.
In the first process of preparing for shooting, the processing device acquires a provisionally set value of the shooting parameter based on one or more of the maximum luminances acquired by the first process of adjusting the shooting parameter.
In the projection preparation process, the processing device takes a picture by the taking picture device using the provisional set value of the picture taking parameter.
After the projection preparation process, the processing device performs the shooting preparation second process.
In the shooting preparation second processing, the processing device performs one or more shooting parameter adjustment second processing while changing the shooting parameters.
In each of the second processings for adjusting the imaging parameters, the processing apparatus projects the bright portion at least once with respect to the predetermined position by the projection apparatus, and the imaging apparatus captures one or more images. , Acquires the maximum brightness which is the maximum value of the brightness at the predetermined position.
The processing device is an inspection unit that acquires a set value of the imaging parameter in the inspection process based on one or more of the maximum luminances acquired by the imaging parameter adjustment second process in the imaging preparation second process. The inspection unit according to claim 3.
The imaging parameter is an inspection unit which is the exposure time and sensitivity of the imaging apparatus. A program for causing a computer to function as a processing device in any of the inspection units of claims 2 to 4. A storage medium that stores the program of claim 5.

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