Visual inspection device, visual inspection device control method, and visual inspection device control program

Abstract

To provide an appearance examination device which makes it easier to detect a defect in an optically transparent examination target including a step.SOLUTION: The appearance examination device includes: a surface light source having a plurality of pixels arranged in a matrix and emitting light to apply on an examination target; pixel luminance control means for controlling the luminance of each of the pixels; and thickness information acquisition means for acquiring thickness information showing the thickness of the examination target of each coordinate on the surface of the surface light source. The pixel luminance control means controls the luminance of the pixels so that a transmission light intensity distribution becomes more uniform on the basis of the thickness information, the distribution being a distribution of the intensity of transmission light having passed through the examination target after being emitted from the surface light source and also being a distribution of the inside of the surface for examining the examination target.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a visual inspection device and the like. [Background technology]

[0002] In production lines where products are manufactured by combining multiple components, inspections are conducted on each component to prevent the production of defective products. Among these components are transparent or translucent light-transmitting components. For such light-transmitting components, visual inspections are generally performed to detect defects such as scratches and cracks. Such light-transmitting components are classified into those with a uniform thickness and those with a variable thickness. In general, detecting defects in light-transmitting components with a variable thickness is more difficult than in those with a uniform thickness.

[0003] In this regard, a defect inspection device technology is disclosed in, for example, Patent Document 1. This defect inspection device attempts to facilitate the detection of defects in a light-transmitting member having a non-uniform thickness. This defect inspection device uses a flat panel display as a light source. The defect inspection device generates a ring-shaped illumination light. At this time, the defect inspection device divides the ring-shaped illumination light into multiple sections and displays each divided section in turn to acquire an image of the inspection object (inspected object). The defect inspection device then combines each of the acquired images and detects defects in the inspection object based on the combined image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-003343 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology of Patent Document 1, a defect inspection device illuminates an inspection object at different angles. The defect inspection device then combines multiple images taken at this time to detect defects in the inspection object. For this reason, the defect inspection device of Patent Document 1 is suitable for detecting defects with smoothly varying thickness, such as in eyeglass lenses. However, when an inspection object includes a step where the thickness changes step-like, a shadow is generated at the step. For this reason, the defect inspection device of Patent Document 1 has the problem of being unable to effectively detect defects in an inspection object that includes a step.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an appearance inspection device and the like that makes it easy to detect defects in a light-transmitting inspection object that includes a step. [Means for solving the problem]

[0007] In order to solve the above problems, the appearance inspection device of the present invention comprises a surface light source having a plurality of pixels arranged in a matrix and emitting light to irradiate the object to be inspected, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, and a thickness information acquisition means for acquiring thickness information representing the thickness of the object to be inspected for each coordinate on the surface of the surface light source, and the pixel brightness control means controls the brightness of each of the pixels based on the thickness information so that the transmitted light intensity distribution, which is the distribution of the intensity of the transmitted light emitted from the surface light source and transmitted through the object to be inspected, approaches uniformity.

[0008] In addition, the control method for an appearance inspection device of the present invention is a control method for an appearance inspection device having a surface light source having a plurality of pixels arranged in a matrix and emitting light to be irradiated onto an object to be inspected, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, and a thickness information acquisition means for acquiring thickness information representing the thickness of the object to be inspected for each coordinate on the surface of the surface light source, wherein the pixel brightness control means controls the brightness of each of the pixels based on the thickness information so that the transmitted light intensity distribution, which is the distribution of the intensity of the transmitted light emitted from the surface light source and transmitted through the object to be inspected, approaches uniformity.

[0009] In addition, the control program for an appearance inspection device of the present invention is a control program for an appearance inspection device having a surface light source having a plurality of pixels arranged in a matrix and emitting light to be irradiated onto an object to be inspected, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, and a thickness information acquisition means for acquiring thickness information representing the thickness of the object to be inspected for each coordinate on the surface of the surface light source, wherein the pixel brightness control means causes a computer to execute a process of controlling the brightness of each of the pixels based on the thickness information so that the transmitted light intensity distribution, which is the distribution of the intensity of the transmitted light emitted from the surface light source and transmitted through the object to be inspected within the surface to be inspected of the object to be inspected, approaches uniformity. [Effects of the Invention]

[0010] The effect of the present invention is to provide a visual inspection apparatus and the like that can easily detect defects in an optically transparent inspection object that includes a step. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a visual inspection apparatus according to a first embodiment; [Figure 2] 4 is a flowchart showing the operation of the visual inspection apparatus of the first embodiment. [Figure 3] 1 is a schematic diagram showing a state in which an inspection object including a step is placed in the visual inspection apparatus of the first embodiment. [Figure 4] 10 is an example of a graph showing the relationship between pixel brightness and transmitted light intensity for light-transmitting materials of different thicknesses. [Figure 5] 1 is a block diagram showing a first specific example of the configuration of a visual inspection apparatus according to a first embodiment. [Figure 6] FIG. 2 is a block diagram showing a second specific example of the configuration of the visual inspection apparatus according to the first embodiment. [Figure 7] 10 is an example of a graph showing the relationship between pixel brightness and transmitted light intensity for light-transmitting materials of different thicknesses. [Figure 8]10 is a flowchart showing the operation of a second specific example of the configuration of the visual inspection apparatus according to the first embodiment. [Figure 9] 3 is an example of an image of an inspection object when pixel luminance is kept constant in the appearance inspection apparatus of the first embodiment. [Figure 10] 4 is an example of a luminance pattern of pixels of the visual inspection apparatus of the first embodiment. [Figure 11] 2 is an example of an image of an inspection target obtained by the visual inspection apparatus of the first embodiment. [Figure 12] 1 is a schematic diagram showing a flaw on an inspection object when photographed by the visual inspection apparatus of the first embodiment while controlling pixel luminance to a constant level. FIG. [Figure 13] 1 is a schematic diagram showing a scratch on an inspection target of the visual inspection apparatus of the first embodiment. FIG. [Figure 14] 3 is a schematic diagram showing reflected light generated at a step portion of the visual inspection apparatus of the first embodiment. FIG. [Figure 15] 4 is an example of an image of a step portion photographed by the visual inspection device of the first embodiment. [Figure 16] FIG. 10 is a block diagram showing a visual inspection apparatus according to a second embodiment. [Figure 17] FIG. 10 is a block diagram showing a defect detection means of a visual inspection apparatus according to a second embodiment. [Figure 18] 10 is a flowchart showing the operation of the visual inspection apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the embodiments described below are limited to technically preferable aspects for carrying out the present invention, but are not intended to limit the scope of the invention. Note that similar components in each drawing are given the same reference numerals, and their description may be omitted.

[0013] (First embodiment) 1 is a block diagram showing a visual inspection apparatus 100 according to the first embodiment. The visual inspection apparatus includes a surface light source 10, a pixel luminance control means 20, and a thickness information acquisition means 30.

[0014] The surface light source 10 has a plurality of pixels arranged in a matrix. Each pixel emits light to irradiate the inspection object 90. The surface light source 10 can be, for example, a telecentric illumination. Here, telecentric illumination is a type of illumination in which light emitted from each pixel is collimated in a direction perpendicular to the main surface of the surface light source 10. Furthermore, for example, a flat panel display can be used as the surface light source 10. Specific examples of flat panel displays that can be used include a liquid crystal panel, an organic EL (Electro-Luminescence) panel, and an LED (Light Emitting Diode) panel.

[0015] The thickness information acquiring means 30 acquires thickness information that indicates the thickness of each position on the inspection object 90. Here, the position refers to a position within the surface to be inspected of the inspection object 90. These positions are expressed, for example, in planar coordinates.

[0016] The pixel luminance control means 20 controls the luminance of each pixel of the surface light source 10. The pixel luminance control means 20 is configured, for example, by a drive circuit and an integrated circuit. The drive circuit drives the pixels, and the integrated circuit controls the drive circuit.

[0017] The pixel brightness control means 20 controls the brightness of each pixel based on the thickness information so that the transmitted light intensity distribution approaches uniformity. Here, transmitted light is light that has passed through the inspection object 90. The light source of the transmitted light is each pixel of the surface light source 10. The transmitted light intensity component is the distribution of transmitted light intensity within the inspection surface of the inspection object 90.

[0018] 2 is a flowchart showing the operation of the visual inspection apparatus 100 of the first embodiment. First, the thickness information acquisition means 30 acquires thickness information of the inspection object 90 (S1). Next, the pixel brightness control means 20 controls the brightness of each pixel so that the transmitted light intensity distribution approaches uniformity (S2). By making the transmitted light intensity distribution more uniform through the above operation, the visual inspection apparatus 100 can create a state in which the user can easily visually recognize defects in the inspection object 90.

[0019] Next, a method for making the transmitted light intensity distribution closer to uniform will be described in detail. Fig. 3 is a schematic diagram showing a state in which an inspection object including a step is placed in the visual inspection apparatus 100 of the first embodiment. The inspection object 90 is placed on the surface light source 10. Fig. 3 shows an example in which the thickness d of the inspection object 90 is configured with five types, d1 to d5. Here, it is assumed that d1 to d5 have the relationship d1>d2>d3>d4>d5.

[0020] Fig. 4 is an example of a graph showing the relationship between pixel brightness and transmitted light intensity for light-transmitting materials of different thicknesses. As shown in Fig. 4, transmitted light intensity I is proportional to pixel brightness L. Furthermore, the thicker the light-transmitting material constituting the inspection object 90, the smaller the transmitted light intensity I at the same brightness L. Generally, the following relationship exists between incident light intensity I0, transmitted light intensity I, and thickness d (Lambert's law): I=I0·exp (-αd) , where α is the absorption coefficient (Eq. 1) In the visual inspection apparatus 100, I0 corresponds to the pixel brightness L. Now, if the target value of the transmitted light intensity I to be made closer to uniform is the target transmitted light intensity Is, and the brightness L for that purpose is the set brightness Ls, then: Is=L·exp (-αd) (Formula 2) Therefore, Ls=Is / exp (-αd) (Formula 3) The luminance of the pixel may be controlled so that

[0021] Figure 4 also lists the luminance required to achieve the target transmitted light intensity Is. Here, the luminance L is L1s for thickness d1, L2s for thickness d2, L3s for thickness d3, L4s for thickness d4, and L5s for thickness d5. If the graph in Figure 4 has been created in advance, it is possible to determine the luminance L to be set based on the graph without using a formula.

[0022] Next, an example of a specific configuration of the appearance inspection device 100 will be described. FIG. 5 is a block diagram showing a first specific example of the configuration of the appearance inspection device 100 of the first embodiment. In the appearance inspection device 100 of the first specific example, the thickness information acquisition means 30 includes a design information acquisition means 31. Furthermore, the pixel brightness control means 20 includes a set brightness calculation unit 21 and a brightness control unit 22.

[0023] The design information acquisition means 31 acquires design information of the inspection object 90 from, for example, an external database, etc. The design information includes thickness information of the inspection object 90.

[0024] The set luminance calculation unit 21 uses Equation 3 and the thickness information to calculate the set luminance Ls for bringing the transmitted light intensity closer to the target transmitted light intensity Is.

[0025] The luminance control unit 22 controls the luminance of each pixel. The luminance that the luminance control unit 22 controls is the set luminance Ls.

[0026] As described above, by making the transmitted light intensity distribution closer to uniform, the visual inspection apparatus 100 of the first specific example can create a state in which the user can easily visually recognize defects in the inspection object 90.

[0027] 6 is a block diagram showing a second specific example of the configuration of the appearance inspection apparatus of the first embodiment. The appearance inspection apparatus 100 of the second specific example includes a transmitted light intensity measuring means 40. The transmitted light intensity measuring means 40 includes, for example, a camera 41 and an image acquisition unit 42. Furthermore, in the appearance inspection apparatus 100 of the second specific example, the thickness information acquisition means 30 includes a transmitted light intensity distribution calculation unit 32 and a thickness information calculation unit 33.

[0028] When calculating thickness information, first, pixel brightness control means 20 controls the brightness of multiple pixels to be uniform. Then, transmitted light intensity distribution calculation unit 32 calculates the transmitted light intensity distribution based on the image of inspection object 90 acquired by image acquisition unit 42. Thickness information calculation unit 33 calculates the thickness of each location on inspection object 90 based on transmitted light intensity distribution calculation unit 32. Then, thickness information calculation unit 33 generates thickness information.

[0029] FIG. 7 is an example of a graph showing the relationship between pixel brightness and transmitted light intensity for translucent materials of different thicknesses. The graph in FIG. 7 is the same as the graph in FIG. 4. However, FIG. 7 also includes the transmitted light intensities I1i, I2i, I3i, I4i, and I5i when the pixel brightness control means 20 controls the brightness L of all pixels to the initial brightness Li. As is clear from FIG. 7, when the pixel brightness control means 20 controls the brightness L of each pixel to the same initial brightness Li, the transmitted light intensity I decreases as the thickness increases. In other words, the pixel brightness L and transmitted light intensity I are related by Equation 1. Therefore, using Equation 1, the thickness information calculation unit 33 can calculate an estimated thickness for each location on the inspection object 90 from the transmitted light intensity I.

[0030] 8 is a flowchart showing the operation of a second specific example of the configuration of the appearance inspection apparatus of the first embodiment. First, the pixel luminance control means 20 controls all pixels of the surface light source 10 to have uniform luminance and irradiates light onto the inspection object 90 (S101). Next, the transmitted light intensity distribution calculation unit 32 calculates the transmitted light intensity distribution of the inspection object 90 (S102). Next, the thickness information calculation unit 33 generates thickness information based on the transmitted light intensity distribution (S103). Next, the pixel luminance control means 20 controls the luminance of each pixel so that the transmitted light intensity distribution approaches uniformity (S104).

[0031] As described above, in the visual inspection apparatus 100 of the second specific example, the thickness information acquiring means 30 can generate thickness information based on the transmitted light intensity distribution obtained by actually measuring the thickness information. Then, by making the transmitted light intensity distribution closer to uniform based on the value of the inspection object 90, the visual inspection apparatus 100 of the second specific example can create a state in which the user can easily visually recognize defects in the inspection object 90.

[0032] (Example) 9 is an example of an image of an inspection object when pixel brightness is kept constant in the visual inspection apparatus 100 of the first embodiment. Bright areas in FIG. 9 correspond to areas where the inspection object 90 is thin, and dark areas correspond to areas where the inspection object 90 is thick.

[0033] Fig. 10 shows an example of a pixel brightness pattern of the visual inspection apparatus 100 of the first embodiment. In the dark areas of Fig. 9, i.e., areas where the thickness of the inspection object 90 is thick, the pixel brightness control means 20 controls the pixel brightness to be high. In the bright areas of Fig. 9, i.e., areas where the thickness of the inspection object 90 is thin, the pixel brightness control means 20 controls the pixel brightness to be low.

[0034] 11 shows an example of an image of an object to be inspected by the visual inspection apparatus 100 of the first embodiment. Compared to FIG. 9, the transmitted light intensity distribution is closer to uniformity.

[0035] The following is a specific example of an image taken by the visual inspection device 100. In this example, the transmitted light intensity distribution is closer to uniform. This makes the defect easier to see. FIG. 12 is a schematic diagram showing a scratch 99 on an inspection target photographed by the visual inspection device 100 of the first embodiment. This schematic diagram shows an image in which pixel brightness is controlled to a constant level. Note that in this example, the scratch 99 overlaps a thick portion 90a that appears dark in a dark portion of the image. Because the dark portions overlap, the scratch 99 is difficult to see.

[0036] Fig. 13 is a schematic diagram showing a scratch that is an object of inspection by the visual inspection apparatus 100 of the first embodiment. In Fig. 13, the brightness of the thick portion 90a and the thin portion 90b are similar. Therefore, the scratch 99, which appears dark, is easily visible.

[0037] Next, exception processing will be described. When the optical system of the surface light source 10 is telecentric, that is, when the light does not spread but travels uniformly in a direction perpendicular to the main surface of the surface light source 10, it is relatively easy to make the transmitted light intensity distribution nearly uniform over a wide area of ​​the inspection object 90. However, if there is a step on the inspection object 90, the area near the step may become dark.

[0038] FIG. 14 is a schematic diagram showing reflected light generated at a step portion 90c in the visual inspection apparatus 100 of the first embodiment. FIG. 14 shows that reflected light occurs at the sidewall portion of the step portion 90c. Although not shown, refracted light also occurs. Such reflected and refracted light occurs because the sidewall of the step portion 90c is not perpendicular to the main surface of the surface light source. Furthermore, the blunted (rounded) corners of the step portion 90c also prevent light from traveling in a straight line. For these reasons, the transmitted light intensity at the step portion 90c tends to be smaller than the intensity estimated from the thickness. In other words, the image of the step portion 90c tends to be dark. FIG. 15 shows an example of an image of a step portion captured by the visual inspection apparatus 100 of the first embodiment.

[0039] As described above, the transmitted light intensity at the step portion 90c is lower than the value predicted from the thickness. Therefore, if the position of the step portion 90c is known from the design information, the pixel luminance control means 20 excludes the step portion 90c from the target for controlling pixel luminance based on the thickness information. The pixel luminance control means 20 then controls the luminance of the pixel corresponding to the step portion 90c to a first luminance higher than the luminance calculated based on the thickness. The value of the first luminance is determined, for example, based on experimental results. Specifically, the first luminance is determined, for example, by multiplying the set luminance Ls calculated from the thickness information by a constant greater than 1 or by setting it to a fixed value close to the rated luminance of the pixel. In this way, by setting the luminance of the pixel corresponding to the step portion 90c exceptionally high, the appearance inspection apparatus 100 can make the transmitted light intensity distribution closer to uniform.

[0040] The appearance inspection apparatus 100 and the like according to this embodiment have been described above.

[0041] The appearance inspection apparatus 100 of this embodiment includes a surface light source 10, a pixel luminance control means 20, and a thickness information acquisition means 30. The surface light source 10 includes a plurality of pixels that emit light to irradiate the object of inspection. The pixels are arranged in a matrix. The pixel luminance control means 20 controls the luminance of each of the plurality of pixels. The thickness information acquisition means 30 acquires thickness information. The thickness information represents the thickness of the object of inspection 90 for each coordinate on the surface of the surface light source 10. The pixel luminance control means 20 controls the luminance of each pixel based on the thickness information so that the transmitted light intensity distribution approaches uniformity. Here, the transmitted light intensity distribution refers to the distribution of the intensity of transmitted light emitted from the surface light source 10 and transmitted through the object of inspection 90, and is the distribution within the surface of the object of inspection 90 being inspected. In the above configuration, the pixel luminance control means 20 controls the luminance of each pixel based on the thickness information so that the transmitted light intensity distribution approaches uniformity. Therefore, even if the inspection object 90 has steps and is not uniform in thickness, the transmitted light intensity distribution approaches uniformity. In other words, the brightness of the inspection object 90 approaches uniformity regardless of location, improving the visibility of defects.

[0042] According to another embodiment, the thickness information acquisition means 30 of the visual inspection apparatus 100 includes design information acquisition means 31. The design information acquisition means 31 acquires design information of the inspection object 90. Furthermore, the design information acquisition means 31 acquires thickness information from the design information. Because the design information includes thickness information as a numerical value, the pixel brightness control means 20 can acquire the control target for each pixel brightness by simple calculation.

[0043] According to another aspect, when a step is included in the design information, the pixel brightness control means 20 of the visual inspection device 100 excludes pixels corresponding to the step from the brightness control based on the thickness information. The pixel brightness control means 20 then adjusts these pixels to a first brightness. The first brightness is determined separately from the above control. At a step, some of the light rays do not travel in a straight line, resulting in a dark image. However, by making the above adjustment, the visual inspection device 100 can make the brightness distribution of the inspection object 90 closer to uniformity.

[0044] According to another embodiment, the visual inspection apparatus 100 further includes a transmitted light intensity measuring means 40. The transmitted light intensity measuring means 40 measures the intensity of transmitted light emitted from the surface to be inspected of the inspection object 90 at each position. The thickness information acquiring means 30 acquires the transmitted light intensity distribution when the pixel brightness control means 20 controls the brightness of multiple pixels to be uniform. The thickness information acquiring means 30 then calculates thickness information of the inspection object 90 based on the acquired transmitted light intensity distribution. This configuration allows the transmitted light intensity distribution to be actually measured. The thickness information acquiring means also estimates the thickness based on the measured value of the transmitted light intensity distribution. Therefore, the visual inspection apparatus 100 can estimate thickness information even if the thickness distribution of the inspection object 90 is unknown. The visual inspection apparatus 100 can then make the brightness distribution of the inspection object 90 closer to uniform based on the thickness information.

[0045] According to another embodiment, the visual inspection apparatus 100 further includes a defect detection means 50. The defect detection means 50 detects defects in the inspection object 90 based on an image of the inspection object 90 formed by transmitted light. The image used here is an image obtained when the pixel brightness control means 20 controls the brightness of each pixel so that the transmitted light intensity distribution approaches uniformity.

[0046] The control method for the appearance inspection apparatus of this embodiment controls the appearance inspection apparatus 100, which includes a surface light source 10, a pixel brightness control means 20, and a thickness information acquisition means 30. Here, the surface light source 10 includes a plurality of pixels that emit light to irradiate the object of inspection. The pixels are arranged in a matrix. The pixel brightness control means 20 controls the brightness of each of the plurality of pixels. The thickness information acquisition means 30 acquires thickness information. The thickness information represents the thickness of the object of inspection 90 for each coordinate on the surface of the surface light source 10. In the control method for the appearance inspection apparatus of this embodiment, the pixel brightness control means 20 controls the brightness of each pixel so that the transmitted light intensity distribution approaches uniformity. This control is performed based on the thickness information. Here, the transmitted light intensity distribution is the distribution of the intensity of transmitted light that has passed through the object of inspection 90, that is, the distribution within the surface of the object of inspection 90 being inspected. The light that is the source of the transmitted light is emitted from the surface light source 10. In the above configuration, the pixel brightness control means 20 controls the brightness of each pixel based on thickness information so that the transmitted light intensity distribution approaches uniformity. Therefore, even if the inspection object 90 includes steps and has an uneven thickness, the transmitted light intensity distribution approaches uniformity. In other words, the brightness of the inspection object 90 approaches uniformity regardless of location. Therefore, the control method for an appearance inspection apparatus of this embodiment can control the appearance inspection apparatus 100 so as to improve the visibility of defects.

[0047] The control program for the visual inspection apparatus of this embodiment causes a computer to execute a process for controlling the visual inspection apparatus 100, which includes a surface light source 10, a pixel brightness control means 20, and a thickness information acquisition means 30. Here, the surface light source 10 includes a plurality of pixels that emit light to irradiate the object of inspection. The pixels are arranged in a matrix. The pixel brightness control means 20 controls the brightness of each pixel. The thickness information acquisition means 30 acquires thickness information of the object of inspection 90. The thickness information represents the thickness of the object of inspection 90 for each coordinate on the surface of the surface light source 10. The control program for the visual inspection apparatus of this embodiment causes the computer to execute a process in which the pixel brightness control means 20 controls the brightness of each pixel so that the transmitted light intensity distribution approaches uniformity. This control is performed based on the thickness information. Here, the transmitted light intensity distribution is the distribution of the intensity of transmitted light that has passed through the object of inspection 90. The light that is the source of the transmitted light is emitted from the surface light source 10. In the above configuration, the control program for the visual inspection apparatus causes the computer to execute a process for controlling the brightness of each pixel based on thickness information so that the transmitted light intensity distribution approaches uniformity. Therefore, even if the thickness of the inspection object 90 is not uniform, the control program for the visual inspection apparatus causes the computer to execute a process for making the transmitted light intensity distribution approach uniformity. In other words, the brightness of the inspection object 90 approaches uniformity regardless of location. Therefore, the control program for the visual inspection apparatus of this embodiment causes the computer to execute a process for controlling the visual inspection apparatus 100 so as to improve the visibility of defects.

[0048] (Second embodiment) In the first embodiment, it was described that the visual inspection apparatus 100 improves the visibility of defects in the inspection object 90, but the entity that detects the defects was not specified. However, it is also possible for the visual inspection apparatus 100 to detect defects. FIG. 16 is a block diagram showing a visual inspection apparatus 101 of a second embodiment. The visual inspection apparatus 101 includes a defect detection means 50 in addition to the configuration of the second specific example (FIG. 6) of the visual inspection apparatus 100 of the first embodiment. Note that the other configurations are the same as those of the visual inspection apparatus 100 of the second specific example, and therefore description thereof will be omitted.

[0049] 17 is a block diagram showing the defect detection means 50 of the visual inspection apparatus 101 of the second embodiment. The defect detection means 50 includes a reference image holding unit 51 and a defect determination unit 52.

[0050] The reference image storage unit 51 stores a reference image. The reference image is an image of a defect-free reference product of the inspection object 90, captured by the pixel brightness control means 20, with the brightness of each pixel controlled so that the transmitted light intensity distribution approaches uniformity. If a defect-free image cannot be obtained from the captured images, an image of the inspection object 90 with few defects can be used. In this case, the reference image may be generated by erasing all defects from the image of the inspection object 90 with few defects. The pixel brightness control means 20 also stores the pixel brightness arrangement when the reference image was captured as a reference brightness pattern.

[0051] The defect determination unit 52 compares the image of the inspection object 90 captured by controlling the pixel brightness using the reference brightness pattern with the reference image. The defect determination unit 52 then detects a defect based on the difference between the two images. For example, the defect determination unit 52 detects a defect when the difference in brightness between the reference image and the captured image of the inspection object 90 is equal to or greater than a threshold value.

[0052] 18 is a flowchart showing the operation of the visual inspection apparatus 101 of the second embodiment. First, the visual inspection apparatus 101 controls the pixels of the surface light source 10 to a reference luminance pattern (S201). Next, the transmitted light intensity measuring means 40 captures a transmitted light image of the inspection object 90 (S202). Next, the defect determination unit 52 compares the captured transmitted light image of the inspection object 90 with the reference image. Then, the defect determination unit 52 determines that a location where the difference in brightness is equal to or greater than a threshold is a defect, and detects the defect (S203).

[0053] As described above, the visual inspection apparatus 101 can detect defects with improved defect visibility.

[0054] The visual inspection apparatus 101 of this embodiment has been described above.

[0055] The visual inspection apparatus 101 of this embodiment includes a defect detection means 50 in addition to the configuration of the visual inspection apparatus 100 of the first embodiment. The defect detection means 50 acquires an image of the inspection object 90 formed by transmitted light. Here, the image acquired by the defect detection means 50 is an image obtained when the pixel luminance control means 20 controls the luminance of each pixel so that the transmitted light intensity distribution approaches uniformity. The defect detection means 50 then detects defects in the inspection object 90 based on the acquired image of the inspection object 90. With this configuration, the visual inspection apparatus 101 can detect defects with improved defect visibility. As a result, the visual inspection apparatus 100 can detect defects more accurately.

[0056] The scope of the present invention also includes a program for causing a computer to execute the processing of the first or second embodiment described above, and a recording medium storing the program. Examples of recording media that can be used include a magnetic disk, a magnetic tape, an optical disk, a magneto-optical disk, and a semiconductor memory.

[0057] The present invention has been described above using the first and second embodiments as exemplary examples. However, the present invention is not limited to the above embodiments. In other words, the present invention can be applied in various aspects that are understandable to those skilled in the art within the scope of the present invention. [Explanation of symbols]

[0058] 10 surface light source 20 Pixel brightness control means 21 Setting brightness calculation section 22 Brightness control section 30 Thickness information acquisition means 31 Design information acquisition means 32 Transmitted light intensity distribution calculation section 33 Thickness information calculation unit 41 Camera 42 Image acquisition unit 40 Transmitted light intensity measurement means 50 Defect detection means 51 Reference image storage unit 52 Defect Judgment Section 90 Test Subjects 100, 101 Appearance inspection device

Claims

1. a surface light source including a plurality of pixels arranged in a matrix and emitting light to irradiate an object to be inspected; a pixel brightness control means for controlling the brightness of each of the plurality of pixels; a thickness information acquiring means for acquiring thickness information representing a thickness of the object to be inspected for each coordinate on the surface of the surface light source; and The pixel brightness control means controlling the brightness of each of the pixels based on the thickness information so that a distribution of transmitted light intensity, which is a distribution of the intensity of transmitted light emitted from the surface light source and transmitted through the inspection object within the inspection surface of the inspection object, approaches uniformity; The thickness information acquisition means a design information acquisition means for acquiring design information of the inspection object, and acquiring the thickness information from the design information; When the design information includes a step, The pixel brightness control means the pixel corresponding to the step is excluded from the target of brightness control based on the thickness information, and adjusted to a separately determined first brightness. A visual inspection device characterized by:

2. A surface light source having a plurality of pixels arranged in a matrix and emitting light to irradiate an object to be inspected; a pixel brightness control means for controlling the brightness of each of the plurality of pixels; a thickness information acquiring means for acquiring thickness information representing a thickness of the object to be inspected for each coordinate on the surface of the surface light source; and The pixel brightness control means controlling the brightness of each of the pixels based on the thickness information so that a distribution of transmitted light intensity, which is a distribution of the intensity of transmitted light emitted from the surface light source and transmitted through the inspection object within the inspection surface of the inspection object, approaches uniformity; a transmitted light intensity measuring means for measuring the intensity of the transmitted light at each position on the surface of the inspection object; The thickness information acquisition means the pixel luminance control means acquires the transmitted light intensity distribution when the plurality of pixels are controlled to have uniform luminance; calculating the thickness information based on the transmitted light intensity distribution; A visual inspection device characterized by:

3. a defect detection unit that detects defects in the inspection object based on an image of the inspection object formed by the transmitted light, The defect detection means the pixel luminance control means detects the defect based on an image of the inspection object when the luminance of each pixel is controlled so that the transmitted light intensity distribution approaches uniformity.

3. The visual inspection apparatus according to claim 1 or 2.

4. A control method for a visual inspection device having a surface light source including a plurality of pixels arranged in a matrix and emitting light to irradiate an inspection object, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, and a thickness information acquisition means for acquiring thickness information representing the thickness of the inspection object for each coordinate on the surface of the surface light source, the thickness information acquisition means has design information acquisition means for acquiring design information of the inspection object, and acquires the thickness information from the design information; the pixel luminance control means controls the luminance of each of the pixels based on the thickness information so that a transmitted light intensity distribution, which is a distribution of the intensity of transmitted light emitted from the surface light source and transmitted through the inspection object within the inspection surface of the inspection object, approaches uniformity; When the design information includes a step, the pixel luminance control means excludes the pixel corresponding to the step from the target of luminance control based on the thickness information, and adjusts the pixel to a separately determined first luminance. A method for controlling an appearance inspection apparatus, comprising:

5. A control method for an appearance inspection device having a surface light source having a plurality of pixels arranged in a matrix and emitting light to be irradiated onto an object to be inspected, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, a thickness information acquisition means for acquiring thickness information representing the thickness of the object to be inspected for each coordinate on the surface of the surface light source, and a transmitted light intensity measurement means for measuring the intensity of transmitted light emitted from the surface light source and transmitted through the object to be inspected for each position on the surface of the object to be inspected, the thickness information acquisition means acquires a transmitted light intensity distribution, which is a distribution of the intensity of the transmitted light within the surface to be inspected of the inspection object when the pixel brightness control means controls the plurality of pixels to a uniform brightness, and calculates the thickness information based on the transmitted light intensity distribution; the pixel luminance control means controls the luminance of each of the pixels based on the thickness information so that the transmitted light intensity distribution approaches uniformity. A method for controlling an appearance inspection apparatus, comprising:

6. A control program for an appearance inspection device having a surface light source having a plurality of pixels arranged in a matrix and emitting light to irradiate an inspection object, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, and a thickness information acquisition means for acquiring thickness information representing the thickness of the inspection object for each coordinate on the surface of the surface light source, The thickness information acquisition means has design information acquisition means for acquiring design information of the inspection object, and a process of acquiring the thickness information from the design information; a process in which the pixel luminance control means controls the luminance of each of the pixels based on the thickness information so that a transmitted light intensity distribution, which is a distribution of the intensity of transmitted light emitted from the surface light source and transmitted through the inspection object within the inspection surface of the inspection object, approaches uniformity; When the design information includes a step, the pixel luminance control means excludes the pixel corresponding to the step from the target of luminance control based on the thickness information, and adjusts the pixel to a separately determined first luminance; A control program for an appearance inspection apparatus, characterized in that it is executed by a computer.

7. A control program for an appearance inspection device having a surface light source having a plurality of pixels arranged in a matrix and emitting light to be irradiated onto an object to be inspected, a pixel brightness control means for controlling the brightness of each of the plurality of pixels, a thickness information acquisition means for acquiring thickness information representing the thickness of the object to be inspected for each coordinate on the surface of the surface light source, and a transmitted light intensity measurement means for measuring the intensity of transmitted light emitted from the surface light source and transmitted through the object to be inspected for each position on the surface of the object to be inspected, a process in which the thickness information acquisition means acquires a transmitted light intensity distribution, which is a distribution of the intensity of the transmitted light within the surface to be inspected of the inspection object when the pixel brightness control means controls the plurality of pixels to a uniform brightness, and calculates the thickness information based on the transmitted light intensity distribution; a process in which the pixel luminance control means controls the luminance of each of the pixels based on the thickness information so that the transmitted light intensity distribution approaches uniformity; A control program for an appearance inspection apparatus, characterized in that it is executed by a computer.

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