JP2008249568A - Visual examination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual examination device capable of accurately and properly inspecting various flaws produced in the appearance of an article. <P>SOLUTION: Four kinds of illuminations, that is, transmission type dark area illumination 26, reflection type dark field illumination 27, transmission type bright field illumination 28 and reflection type bright field illumination 29 are provided to the visual examination device 10 so as to be respectively changed over, without changing the positional relation of a CCD area sensor 23 and a lens 16 to be inspected. The visual examination device 10 is constituted so that four kinds of the illuminations are changed over to photograph the lens 16, respective images are used to perfectly detect the flaws produced in the surface or interior of the lens 16 and classified into either quality of good or poor and reinspection of the lens 16. Four kinds of images of the lens 16 classified to reinspection are easily and accurately compared with each other, and the presence or degree of the flaw of the lens 16 is precisely inspected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an appearance inspection apparatus for inspecting an article for defects.

  Electronic devices used in precision instruments, and optical devices such as lenses and image sensors often have a great influence on the performance even if they have some defects such as scratches and scratches. However, it is practically impossible to completely remove such defects from various factors during manufacturing. Therefore, in practice, the appearance and performance are carefully inspected before shipment, and only those satisfying certain standards are shipped as products.

  Although such inspections such as appearances are automated, it is difficult to quantitatively evaluate various defects, and many inspection items still have to rely on visual inspection. The visual inspection is greatly influenced by the skill level and physical condition of the inspection, and is not necessarily a stable inspection. Further, the inspection speed of the visual inspection is not necessarily fast, and it is most preferable to inspect all products correctly. However, in actuality, in many cases, the visual inspection often involves sampling some products.

  In recent years, in view of such problems of visual inspection, there has been proposed an appearance inspection apparatus that reduces the amount of visual inspection and accurately and efficiently inspects the appearance and the like. For example, based on the maximum brightness in the image obtained by imaging the article to be inspected, the article is determined as a non-defective product, a defective product, or a non-determinable product, and re-inspected as necessary based on this determination An appearance inspection apparatus that performs the above is known (see Patent Document 1).

An apparatus for inspecting the appearance of a lens based on an image obtained by imaging the lens while illuminating a dark field is known (see Patent Document 2).
JP-A-9-264856 JP 2002-90258 A

  However, if a defect is detected using the maximum luminance in an image obtained by imaging an article as in the appearance inspection apparatus described in Patent Document 1, a low-luminance defect such as a stain cannot be correctly determined. There is a problem.

  If you try to detect such low-brightness defects by adjusting the camera position, lighting direction, illumination light intensity, etc., the high-brightness defects will be emphasized more than necessary, and they should be good. Many so-called over-detections that are regarded as defective products occur. That is, there is a problem that it cannot always be said that an accurate and efficient inspection can be performed on an article in which various defects are randomly generated.

  Further, as in the inspection apparatuses described in Patent Documents 1 and 2, in order to devise the position of the camera with respect to the article, the direction of illumination, the intensity of illumination light, the wavelength, etc., a plurality of cameras and illumination along the inspection line If a defect is not detected by one set of cameras or lighting, a defect may be detected if appropriate shooting conditions are obtained for another set. However, when the article to be inspected is moved on the inspection line or the like, the position of the article with respect to each camera or each illumination is different. Therefore, although the images separately photographed using a plurality of cameras and lighting sets in this manner are images in which various defects are respectively copied, the photographing angle of the article to be inspected is inspected. There is a problem that it is difficult to compare these images with each other with high accuracy because each time the lens is photographed.

  Realistic articles have a three-dimensional shape, and the characteristics of defects that occur here are various. Therefore, in the case where images taken by a large number of cameras and lighting cannot be compared with each other with high accuracy, in order to detect such defects without omission, a large number of cameras and lighting that are unrealistic in cost are necessary. End up. That is, in reality, there is a problem that various defects cannot be detected with high accuracy.

  On the other hand, in the case of a visual inspection device that uses both automatic inspection and visual inspection, such as re-inspection that is difficult to judge by automatic inspection and re-inspection by visual inspection, Under the situation where the quality of the product is not stable as in the initial stage of manufacturing, a large amount of reinspected products are generated. Therefore, there is a problem in that even if an appearance inspection apparatus that uses such a visual inspection is introduced, the manufacturing is not always efficient.

  The present invention has been made in view of the above-described problems, and provides an appearance inspection apparatus capable of accurately and accurately inspecting a wide variety of defects that occur randomly in an article having a realistic shape. With the goal. It is another object of the present invention to provide an appearance inspection apparatus that can efficiently inspect the appearance and the like.

  The appearance inspection apparatus according to the present invention includes an imaging unit that images a subject whose appearance is to be inspected, and the subject so that the subject and the imaging unit can be switched to each other without changing a relative position. And a plurality of illumination means for uniformly illuminating from different directions.

  In addition, a first illuminating unit is provided on the opposite side of the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light transmitted through the subject does not enter the imaging unit. It is characterized by that.

  A second illuminating unit that is disposed on the same side as the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light reflected by the subject does not enter the imaging unit; It is characterized by providing.

  In addition, a third illuminating unit that is disposed on the opposite side of the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light transmitted through the subject is incident on the imaging unit is provided. It is characterized by that.

  A fourth illuminating unit that is arranged on the same side as the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light reflected by the subject is incident on the imaging unit; It is characterized by providing.

  When the subject is illuminated by the second illumination unit or the fourth illumination unit, the first illumination unit is disposed at a position facing the imaging unit.

  The appearance inspection apparatus of the present invention includes an imaging unit that images a subject whose appearance is to be inspected, and illumination light that is disposed on the opposite side of the imaging unit with respect to the subject and that transmits the subject. First illuminating means for uniformly illuminating the subject so as not to be incident on the subject, and illumination light that is disposed on the same side as the imaging means with respect to the subject and reflected by the subject is applied to the imaging means Second illumination means for uniformly illuminating the subject so as not to enter, and illumination light disposed on the opposite side of the imaging means with respect to the subject and passing through the subject enters the imaging means In this way, the third illumination means for uniformly illuminating the subject, and the illumination light that is disposed on the same side as the imaging means with respect to the subject so that the illumination light reflected by the subject enters the imaging means A fourth illuminating means for uniformly illuminating the subject; The first illuminating means, the second illuminating means, the third illuminating means, and the fourth illuminating means are switched between each other without changing a relative position between the subject and the imaging means. It is provided in.

  In addition, the first illumination unit is disposed at a position facing the imaging unit when the subject is illuminated by the second illumination unit or the fourth illumination unit.

  Further, the first illumination unit is an illumination that can be switched by disposing a light shielding plate that blocks light from the third illumination unit in front of the first illumination unit.

  The first illumination unit may be an illumination that can be switched by selectively extinguishing a part of the light emitting surface of the third illumination unit.

  According to the present invention, it is possible to inspect a wide variety of defects that occur randomly in an article having a realistic shape without omission. Further, according to the present invention, it is possible to efficiently perform an appearance inspection.

  As shown in FIG. 1, the appearance inspection apparatus 10 is an appearance inspection apparatus that inspects defects generated on the surface and inside of a lens 16 arranged side by side on an inspection tray 15.

  The lens 16 to be inspected by the appearance inspection apparatus 10 is, for example, a lens formed by heating and pressurizing a glass material with a mold and provided with an antireflection coating. When the appearance inspection apparatus 10 is not used, for example, The lens 16 is subjected to visual inspection using a stereomicroscope.

  The inspection tray 15 is provided with countersink holes 17 in which the lenses 16 are arranged in a lattice pattern. Further, a through hole 18 having a smaller diameter than that of the countersink hole 17 is provided in the center of the countersink hole 17. Further, the through hole 18 is provided so that the diameter increases toward the lower side in order to efficiently guide the illumination light irradiated from below to the lens 16.

  Further, a plurality of similar inspection trays 15 are prepared according to the production amount of the lens 16, but the inspection tray 15 is assigned an ID 19 (see FIG. 2) for identifying each. This ID 19 is, for example, a barcode, which is read when moved to the inspection position, and is managed together with the management number of the lens 16 disposed in the through hole 18.

  The appearance inspection apparatus 10 includes an XY stage 21, an ID scanner 22, a CCD area sensor 23, a transmission type dark field illumination 26, a reflection type dark field illumination 27, a transmission type bright field illumination 28, a reflection type bright field illumination 29, and the like. The

  The XY stage 21 moves the lens 16 together with the set inspection tray 15, and accurately moves the lens 16 that executes the inspection to an inspection position directly below the CCD area sensor 23. The XY stage 21 is provided with a hollow stage on which the inspection tray 15 on which the lens 16 is disposed is set. The hollow stage is provided so as to be movable horizontally and is formed in a hollow frame shape. Accordingly, the central portion of the set inspection tray 15 is exposed downward, and the lens 16 disposed on the inspection tray 15 is illuminated even from below. The XY stage 21 moves the inspection tray 15 to the ID scan position every time the inspection tray 15 is replaced.

  The CCD area sensor 23 is arranged downward, and the lens 16 moved to the inspection position by the XY stage 21, that is, the lens 16 arranged facing the CCD area sensor 23 is photographed under various illumination conditions. To do. The image of the lens 16 taken by the CCD area sensor 23 is managed together with the ID 19 (see FIG. 2) of the inspection tray 15 and the coordinates in the inspection tray 15 where the lens 16 is disposed.

  The transmissive dark field illumination 26 (first illumination means) is disposed on the opposite side of the CCD area sensor 23 with respect to the lens 16 at the inspection position, and is a planar shape that uniformly illuminates the lens 16 with illumination light. A light emitting surface 31 is provided. The entire light emitting surface 31 does not emit light, and a non-light emitting portion 32 is provided at the center of the light emitting surface 31. The illumination light emitted from the transmission type dark field illumination 26 is uniformly emitted from the entire light emitting surface 31 excluding the non-light emitting portion 32. Further, the size and shape of the non-light emitting portion 32 are determined so that the illumination light from the transmissive dark field illumination 26 does not enter the CCD area sensor 23 after passing through the lens 16. The transmissive dark field illumination 26 has a configuration in which a diffusion plate is provided on a large number of LEDs arranged, and the size and shape of the non-light emitting portion 32 can be easily changed.

  The transmission type dark field illumination 26 is provided on the uniaxial stage 33 and freely moves between a use position where the lens 16 is irradiated with illumination light and a non-use position retracted from the use position. Is done. The uniaxial stage 33 for moving the transmission type dark field illumination 26 is provided independently of the XY stage 21 and the CCD area sensor 23 fixing equipment, and the CCD area sensor 23 and the lens 16 at the inspection position. The transmissive dark field illumination 26 is freely moved between the use position and the non-use position without changing the relative positional relationship.

  The reflective dark field illumination 27 (second illumination means) is arranged on the same side as the CCD area sensor 23 with respect to the lens 16 at the inspection position. The reflection type dark field illumination 27 is a cylindrical illumination provided so as to surround the periphery of the lens 16 at the inspection position from above, and the inner surface side is a light emitting surface to uniformly illuminate the lens. Irradiate. The illumination light applied to the reflection type dark field illumination 27 is applied to the lens 16 from an angle closer to the surface of the inspection tray 15 than the reflection type bright field illumination 29 described later. That is, the illumination angle of the reflective dark field illumination 27 is adjusted so that the amount of illumination light reflected by the normal surface of the lens 16 and entering the CCD area sensor 23 is reduced.

  The transmissive bright field illumination 28 (third illumination means) is disposed on the opposite side of the CCD area sensor 23 with respect to the lens 16 at the inspection position, and is a flat surface that uniformly illuminates the lens 16 with illumination light. A light emitting surface 34 is provided. Unlike the light emitting surface of the transmissive dark field illumination 26 described above, the entire light emitting surface 34 of the transmissive bright field illumination 28 emits light uniformly. The size of the light emitting surface 34 of the transmissive bright field illumination 28 is at least larger than the size of the non-light emitting portion 32 of the transmissive dark field illumination 26 described above. That is, the illumination light emitted from the transmissive bright field illumination 28 passes through the lens 16 and enters the CCD area sensor 23.

  The reflective bright field illumination 29 (fourth illumination means) is arranged on the same side as the CCD area sensor 23 with respect to the lens 16 at the inspection position, and uniformly irradiates illumination light from above the lens 16. The illumination light emitted from the reflective bright field illumination 29 is emitted from a direction facing the surface of the inspection tray 15 as compared with the reflective dark field illumination 27 described above. That is, the illumination angle of the reflective bright field illumination 29 is adjusted so that most of the illumination light reflected on the normal surface of the lens 16 enters the CCD area sensor 23.

  The mask plate 36 is provided between the transmissive dark field illumination 26 and the transmissive bright field illumination 28 and the XY stage 21. Further, the mask plate 36 is provided with an opening through which only the lens 16 to be inspected is exposed in front of the CCD area sensor 23, and is emitted from the transmissive dark field illumination 26 and the transmissive bright field illumination 28. Light is irradiated to the lens 16 to be inspected through this opening. Further, the distance between the mask plate 36 and the XY stage and the size of the opening of the mask plate 36 are set to such a size that so-called vignetting does not occur. On the other hand, the mask plate 36 blocks light from the transmissive dark field illumination 26 and the transmissive bright field illumination 28 that are irradiated to the other lenses 16 arranged around the lens 16 to be inspected. Further, the surface of the mask plate 36 is subjected to an antireflection treatment, and the light from the transmissive dark field illumination 26 and the transmissive bright field illumination 28 repeats random reflections and enters the lens 16 to be inspected. prevent.

  The mask plate 37 is provided between the reflective dark field illumination 27 and the XY stage 21. The mask plate 37 is provided with an opening through which only the lens 16 to be inspected is exposed in front of the CCD area sensor 23, and is emitted from the reflective dark field illumination 27 and the reflective bright field illumination 29. Light is irradiated to the lens 16 to be inspected through this opening. In addition, the distance between the mask plate 37 and the XY stage and the size of the opening of the mask plate 37 are determined so as not to cause so-called vignetting. On the other hand, the mask plate 37 blocks light from the reflection type dark field illumination 27 and the reflection type bright field illumination 29 irradiated to other lenses 16 arranged around the lens 16 to be inspected. Further, the surface of the mask plate 37 is subjected to antireflection treatment, and light from the reflective dark field illumination 27 and the reflective bright field illumination 29 repeats random reflections and enters the lens 16 to be inspected. prevent.

  As shown in FIG. 2, the appearance inspection apparatus 10 includes a control unit 41, a basic image processing unit 42, a reference image creation unit 43, a difference image creation unit 44, an evaluation unit 46, a RAM 47, a ROM 48, a data communication unit 49, and the like. Is done.

  The control unit 41 comprehensively controls each unit of the appearance inspection apparatus 10 via the data bus 51. Further, the control unit 41 reads out a control program stored in the ROM 48 and controls each part of the appearance inspection apparatus 10 according to this. For example, the control unit 41 includes the XY stage 21, the ID scanner 22, the uniaxial stage 33, the transmission dark field illumination 26, the reflection dark field illumination 27, the transmission bright field illumination 28, the reflection bright field illumination 29, The CCD area sensor 23 is controlled using a corresponding driver according to the control program of the visual inspection apparatus 10. Further, for example, the control unit 41 specifies the position of the lens 16 to be inspected in the inspection tray 15 from the amount of movement of the XY stage 21, and stores this in the RAM 47.

  The ID scanner 22 reads the ID 19 of the inspection tray 15 moved to the ID scan position, and registers it in a database constructed in the server 76 (described later). The ID 19 registered in the database is managed together with images and inspection results used for the inspection of each lens 16.

  The CCD area sensor 23 includes an imaging lens including a zoom lens, a focus lens, a diaphragm, and the like, and a CCD disposed behind the imaging lens. The CCD area sensor 23 is in the inspection position while being illuminated by any one of the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29. The lens 16 is imaged. At this time, light from the lens 16 to be inspected is imaged on the light receiving surface of the CCD by the imaging lens, and photoelectrically converted into an analog imaging signal proportional to the amount of light received by each pixel of the CCD.

  Note that the zoom and focus of the imaging lens, the aperture area of the diaphragm, the electronic shutter speed of the CCD, etc. are determined in advance according to the shape of the lens 16 to be inspected. Is done.

  The basic image processing unit 42 removes noise from the analog imaging signal output from the CCD area sensor 23, amplifies the signal, and converts the analog imaging signal into digital image data. The digital image data thus obtained from the CCD area sensor 23 is temporarily stored in the RAM 47 as an original image.

  Hereinafter, the original image of the lens 16 illuminated by the transmissive dark field illumination 26 is referred to as a first original image 56. Similarly, the original image of the lens 16 illuminated by the reflective dark field illumination 27 is the second original image 57, the original image of the lens 16 illuminated by the transmissive bright field illumination 28 is the third original image 58, and the reflective bright image. The original image of the lens 16 illuminated by the field illumination 29 is referred to as a fourth original image 59, respectively.

  The reference image creation unit 43 creates a reference image serving as a reference for non-defective products based on an original image obtained by imaging a lens determined to be non-defective by the visual inspection apparatus 10 or visual inspection (hereinafter, non-defective lens). For example, when a plurality of non-defective lenses are illuminated by the transmission type dark field illumination 26 and respective first original images are obtained, the reference image creation unit 43 averages the luminance for each pixel of these first original images 56. To do. Then, a first average luminance image is created in which the average luminance of the first original image of the non-defective lens is the luminance of each pixel. At the same time, the reference image creation unit 43 calculates a standard deviation for each pixel from the first original image 56 of the non-defective lens, and creates a first standard deviation image using the standard deviation as luminance data of each pixel. . Further, the reference image creation unit 43 uses the obtained first average luminance image and first standard deviation image as a reference for a non-defective product when shooting while illuminating with the transmission type dark field illumination 26. Is stored in the RAM 47. The first reference image 61 is, for example, a pixel corresponding to α times the first standard deviation image for the first average luminance image, where α is a predetermined number in accordance with characteristics such as the shape of the lens to be inspected. It is created by adding each.

  Similarly, the reference image creation unit 43 creates a third average luminance image and a third standard deviation image using the third original images 58 of a plurality of non-defective lenses, and based on these, the transmission type bright field illumination 28. A third reference image 63 used as a reference for a non-defective product when shooting while illuminating with is created and stored in the RAM 47.

  On the other hand, when the second original image 57 of the lens 16 to be inspected is acquired, the reference image creation unit 43 determines the luminance data of the target pixel for a certain pixel (referred to as the target pixel) of the second original image 57. Then, local average luminance data is calculated by averaging the luminance data of pixels in a predetermined range around the target pixel. This local average luminance data is calculated for all the pixels of the second original image 57. Then, the reference image creation unit 43 temporarily stores the second local average image using the local average luminance data as the luminance data of each pixel in the RAM 47 as the second reference image 62.

  Similarly, when the fourth image 59 of the lens 16 to be inspected is acquired, the reference image creation unit 43 creates a fourth local average image from the fourth original image 59 and uses this as a fourth reference image 64. , Temporarily stored in the RAM 47.

  The first reference image 61 and the third reference image 63 are performed once when the lens inspection is started, and the same reference images 61 and 63 are used for the subsequent inspections. On the other hand, the second reference image 62 and the fourth reference image 64 are created for each of the lenses 16 to be inspected.

  The difference image creation unit 44 reads out the first original image 56 and the first reference image 61 of the lens 16 to be inspected from the RAM 47, calculates the difference between the pixels, and sets each pixel with the same value as the difference. One difference image 66 is created and stored in the RAM 47. Similarly, the difference image creation unit 44 subtracts the second reference image 62 from the second original image 57 to subtract the second difference image 67 and subtracts the third reference image 63 from the third original image 58 to obtain the third difference image. 68, the fourth reference image 64 is subtracted from the fourth original image 59, and a fourth difference image 69 is created and stored in the RAM 47.

  As described above, when the difference image creation unit 44 creates the first difference image 66, the center of the lens shown in the first original image 56 and the center of the lens of the first reference image 61 generally do not match. However, when the lens 16 is photographed, illumination is reflected inside the lens 16 captured in the original image according to the shape of the surface of the lens 16. In addition, the illumination is also reflected in the inside of the lens imaged in the reference image. The difference image creation unit 44 calculates the center of the lens imaged in the original image and the reference image by using the illumination reflection according to the shape of the surface of the lens 16, and uses this as the center. A first difference image 66 is created. On the other hand, in the case of the third original image 58 and the third reference image 63 when illuminated by the transmission type bright field illumination 28, the whole is photographed brightly. Therefore, the center position of the lens using the reflected illumination is reflected. Not calculated or identified. However, when the entire lens is projected brightly in this way, there is a luminance distribution according to the shape of the lens surface. Therefore, when creating the third difference image 68, the difference image creation unit 44 determines the center of the lens 16 that has been captured in the third original image 58 based on the luminance distribution according to the shape of the surface of the lens 16. calculate.

  The evaluation unit 46 evaluates the quality of the lens 16 by comparing with a predetermined threshold value for each pixel of the difference image. For example, the evaluation unit 46 compares the value of each pixel of the first difference image with a predetermined reference value, counts the total number of pixels exceeding the reference value, and sets the defect area S1. The reference value used here is determined in advance and stored in the RAM 47. Then, the evaluation unit 46 compares the defect area thus obtained with a first threshold value that is set in advance and stored in the RAM 47. The first threshold used here is composed of an upper limit value U1 and a lower limit value L1.

  That is, the first threshold value 71 is a combination of threshold values that define a range, and is determined in advance before the start of the inspection. The value of the first threshold value 71 is determined according to the inspection result such as the defective product rate of the lens 16, and is determined independently for each of the upper limit value U1 and the lower limit value L1. Such adjustment of the threshold value is common to the following second to fourth threshold values, and the first to fourth threshold values are independently determined and the upper limit value and the lower limit value of each threshold value are determined independently.

  When the defect area S1 is smaller than the lower limit value of the first threshold (S1 <L1), the evaluation unit 46 determines that the lens 16 is good. On the other hand, when the defect area is larger than the upper limit value of the first threshold (S1> U1), the evaluation unit 46 determines that the lens 16 is defective. When the defect area S1 is greater than or equal to the lower limit L1 of the first threshold 71 and less than or equal to the upper limit U1 (L1 ≦ S1 ≦ U1), the evaluation unit 46 determines that the lens 16 needs to be reinspected. To do. Thus, the determination of the lens 16 obtained from the comparison between the first difference image 66 and the first threshold value 71 is stored in the RAM 47 as the first determination result.

  Similarly, the evaluation unit 46 counts the defect area S2 of the second difference image and compares it with the second threshold value 72 (upper limit value U2, lower limit value L2). Determine whether any of the re-examination. The determination result of the lens 16 obtained based on the comparison between the second difference image 67 and the second threshold value 72 is stored in the RAM 47 as the second determination result.

  Similarly, the evaluation unit 46 counts the defect area S3 of the third difference image and compares it with the third threshold value 73 (upper limit value U3, lower limit value L3). Determine whether any of the re-examination. The determination result of the lens 16 obtained based on the comparison between the third difference image 68 and the third threshold 73 is stored in the RAM 47 as the third determination result.

  Similarly, the evaluation unit 46 counts the defect area S4 of the fourth difference image and compares it with the fourth threshold value 74 (upper limit value U4, lower limit value L4). Determine whether any of the re-examination. The determination result of the lens 16 obtained based on the comparison between the fourth difference image 69 and the fourth threshold value 74 is stored in the RAM 47 as the fourth determination result.

  And the evaluation part 46 determines final evaluation of the lens 16 based on the above-mentioned 1st-4th determination result. That is, when the first to fourth determination results include a defect determination, the evaluation unit 46 evaluates the lens 16 as a defective product. On the other hand, when the lens 16 is not a defective product, if the first to fourth determination results include reexamination required, the evaluation unit 46 evaluates the lens 16 as a reexamination required product. And when it is not inferior goods and a reexamination required product, the evaluation part 46 evaluates the lens 16 as a non-defective product.

  The evaluation of the lens 16 by the evaluation unit 46 is associated with the ID 19 of the inspection tray 15, the position in the inspection tray 15, the first to fourth difference images used for the evaluation, and the like in the database of the server 76. be registered.

  The RAM 47 is a working memory, and stores the ID of the inspection tray 15, the position of the lens 16 to be inspected in the inspection tray 15, the original image, the reference image, the difference image, the threshold value, the reference value, and the like. The ROM 48 is a memory that stores various settings of the appearance inspection apparatus 10, control programs, various drivers, and the like.

  The data communication unit 49 connects the server 76 provided outside the appearance inspection apparatus 10 and the appearance inspection apparatus 10 via a LAN or the like. Therefore, the evaluation of the lens 16 is constructed in the server 76 through the data communication unit 49 together with the ID of the inspection tray 15, the position of the lens 16 in the inspection tray 15, the first to fourth original images used for the evaluation, and the like. Registered in the registered database.

  Hereinafter, the operation of the appearance inspection apparatus 10 configured as described above will be described. As shown in FIG. 3, when the inspection tray 15 on which the lens 16 to be inspected is placed is set in the appearance inspection apparatus 10, the inspection tray 15 is moved to the ID scan position by the XY stage 21, and the inspection tray is moved by the ID scanner 22. 15 IDs are read. Then, the lens 16 to be inspected is moved directly below the CCD area sensor 23, and the inspection of the lens 16 is started.

  First, the transmission type dark field illumination 26 is moved directly below the lens 16 to be inspected, and an image (first original image) of the lens 16 to be inspected in a state illuminated by the transmission type dark field illumination 26 is acquired. A first difference image 66 is created from the first original image and the first reference image 61. Then, based on the first difference image 66, the quality of the lens 16 is determined as one of good, bad, and reexamination required (first determination result).

  When the first determination result is obtained in this manner, the appearance inspection apparatus 10 switches the illumination to the reflective dark field illumination 27, and an image (second original image) of the lens 16 is acquired. A second difference image 67 is created from the second original image and the second reference image 62. And based on the 2nd difference image 67, the quality of the lens 16 is determined in any of a quality, defect, and a reexamination required (2nd determination result).

  Furthermore, when the second determination result is obtained, the appearance inspection apparatus 10 switches the illumination to the transmissive bright field illumination 28. That is, the uniaxial stage 33 is driven, the transmissive dark field illumination 26 is retracted from directly below the lens 16, and the transmissive bright field illumination 28 is moved directly below the lens 16. The appearance inspection apparatus 10 acquires an image (third original image) of the lens 16 while illuminating the lens 16 with the transmission type bright field illumination 28. A third difference image 68 is created from the third original image and the third reference image 63. And based on the 3rd difference image 68, the quality of the lens 16 is determined to be any of good, bad, and a reexamination required (3rd determination result).

  When the third determination result is obtained, the appearance inspection apparatus 10 switches the illumination to the reflective bright field illumination 29 and acquires the fourth original image. Then, a fourth difference image 69 is created from the fourth original image and the fourth reference image 64. Then, based on the fourth difference image, the quality of the lens 16 is determined as good, defective, or reexamination required (fourth determination result). When the lens 16 is photographed while illuminating with the reflection type bright field illumination 29, the transmission type dark field illumination 26 is disposed at a position facing the CCD area sensor 23.

  When the first to fourth determination results are obtained in this way, the appearance inspection apparatus 10 determines the evaluation of the lens 16 based on these determination results. At this time, if at least one defect determination is included in the first to fourth determination results, the lens 16 is evaluated as a defective product. In addition, if the first to fourth determination results do not include a failure determination and a re-examination determination is necessary, the lens 16 is evaluated as a re-inspection product. On the other hand, the lens 16 is non-defective when the first to fourth determination results do not include both the defect determination and the reexamination determination required, that is, when all the first to fourth determination results are good. It is evaluated. The evaluation of the lens 16 is stored in the server 76 that manages the inspection together with the ID of the inspection tray 15, the position in the inspection tray, the difference image used for the inspection, and the like.

  When the evaluation of one lens 16 is determined in this way, the XY stage 21 is moved, and the same inspection as described above is performed on the other lenses.

  Further, among the lenses 16 inspected by the appearance inspection apparatus 10, the lens 16 evaluated as a re-inspection product is separately subjected to a re-inspection by visual inspection and finally classified as either a good product or a defective product. The In the re-inspection process performed here, the first to fourth original images 56, 57, 58, 59 obtained by the appearance inspection apparatus 10 and registered in the server 76 together with the evaluation by the appearance inspection apparatus 10 are used. Since the first to fourth original images 56, 57, 58, 59 are images obtained by changing the illumination conditions with the positional relationship between the CCD area sensor 23 and the inspected lens 16 being the same, there are various defects. Are shown at the same position in all images at the same angle. Therefore, by displaying these first to fourth original images 56, 57, 58, 59 side by side on a separately prepared display, the presence / absence and degree of defects and the type of each defect are determined.

  Further, as described above, when obtaining an image of the lens 16 to be inspected using the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29, respectively. The types of defects that can be accurately evaluated for each illumination differ. For example, as shown in FIG. 4, the lens 16 immediately before shipment may have various defects such as a scratch 81, a brace 82, a stain 83, a chip 85, a coat missing 91, and a mill 92. Of course, these various defects have different causes and characteristics.

  The scratch 81 is a linear scratch generated on the surface of the lens 16, and the bump 82 is a dotted scratch generated on the surface of the lens 16. The stain 83 is dirt that spreads over and adheres to the surface of the lens 16. Further, the chip 85 is a defect of a shape in which the peripheral edge of the lens 16 is missing. The coating loss 91 is a defect in the antireflection coating, and is a hole in the coating layer. Further, the hour 92 is a defect which is generated inside or on the surface of the lens 16 mainly due to bubbles or the like mixed during molding, and has a refractive index different from that of other normal portions.

  When the lens 16 having such a defect is photographed by illuminating with the transmission type dark field illumination 26 and inspected, the scratch 81 and the protrusion 82 are evaluated with high accuracy. For example, as shown in FIG. 5, in the first original image 56, scratches 81, bushes 82, scratches 83, and hour 92 are easily recognized visually. On the other hand, the chip 85 and the missing coat 91 may be difficult to be recognized depending on the position, angle, defect degree, and the like. For this reason, as the first threshold value 71 to be compared with the defect area S1 of the first difference image 66, an optimal value is selected in order to detect the flaw 81 and the bump 82. Note that the blur 83 is more clearly recognized in the second original image 57 by the reflective dark field illumination 27 and is evaluated based on the second difference image 67 as described later. The millet 92 is also recognized with high accuracy in the first original image 56, but is recognized with the second original image 56 with equal or higher accuracy than this, and thus is evaluated based on the second difference image 67.

  The first original image 56 has an illumination reflection 96 generated according to the shape of the surface of the lens 16. In the first difference image 66, the illumination reflection 96 is sufficient compared to the defect. The brightness is small. Therefore, the inspection of defects automatically performed is not greatly affected, and even a defect on the illumination reflection 96 is evaluated substantially accurately. The same applies to other difference images.

  In addition, when the lens 16 is illuminated with the reflection type dark field illumination 27 and photographed and inspected, the stain 83 and the hour 92 are evaluated with high accuracy. For example, as shown in FIG. 6, in the second original image 57, scratches 81, bushes 82, scratches 83 and hour 92 are easily recognized visually. In particular, the blur 83 is detected almost certainly by the second difference image 67. On the other hand, the missing coat 91 may be difficult to recognize depending on the position and angle where these occur and the degree of defects. In addition, regarding the scratch 81 and the protrusion 82, the first original image 56 by the transmission type dark field illumination 26 is more clearly recognized. For these reasons, an optimal value is selected as the second threshold value 72 to be compared with the defect area S2 of the second difference image 67 in order to evaluate the stain 83 and the hour 92.

  In addition, when the lens 16 is illuminated with the transmissive bright field illumination 28 for photographing and inspection, the chip 85 is accurately evaluated. For example, as shown in FIG. 7, the chip 85 and the hour 92 are easily recognized visually in the third original image 58. On the other hand, the scratch 81, the bulge 82, and the missing coat 91 may be difficult to recognize depending on the position and angle at which these occur and the degree of defects. Further, the blur 83 is hardly recognized in the third original image 58. From these facts, an optimal value is selected as the third threshold value 73 to be compared with the defect area S3 of the third difference image 68 in order to evaluate the chip 85.

  In addition, when the lens 16 is illuminated with the reflection type bright field illumination 29 to photograph and inspect, the missing coat 91 is accurately evaluated. For example, as shown in FIG. 8, a missing coat 91 is easily visually recognized in the fourth original image 59. On the other hand, the scratch 81 and the bump 82 may be difficult to recognize depending on the position and angle where these occur and the degree of defects. Further, the stain 83 and the hour 92 are hardly recognized in the fourth difference image. For these reasons, an optimum value is selected as the fourth threshold value 74 to be compared with the defect area S4 of the fourth difference image 69 in order to accurately evaluate the missing coat 91.

  As described above, the appearance inspection apparatus 10 includes the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29 for one CCD area sensor 23. Various kinds of illumination are provided, and the lens 16 is photographed and inspected using each of them. Therefore, the appearance inspection apparatus 10 can be downsized as compared with the appearance inspection apparatus provided with a plurality of cameras and illuminations on the inspection line. In addition, since the number of cameras and illuminations is the minimum, the appearance inspection apparatus 10 can be provided at a low cost.

  In addition, as described above, the appearance inspection apparatus 10 performs an inspection based on images captured under four types of illumination conditions. Therefore, the position, size, angle, and the like of defects generated on the surface of the lens 16 and the like are determined. It is possible to inspect without leakage regardless of individual characteristics.

  Furthermore, since the defect of the lens 16 is determined from the image under each illumination condition, and these are combined to determine the final evaluation of the lens 16, the evaluation criteria are not inclined to the evaluation of any defect. The quality of the lens 16 can be correctly evaluated by fully considering any of various defects that occur in the defect of the lens 16.

  Furthermore, since the type of defect to be inspected is assigned based on each illumination condition, the threshold value can be easily set according to the feature of the defect generated in the lens 16. In addition, since the evaluation is performed using the threshold value set according to the feature of the defect detected under each illumination condition, the defect can be inspected accurately without omission, and the stability and reliability of the inspection are improved.

  Further, as described above, the evaluation of the lens 16 under various illumination conditions is performed by comparing the defect area with a threshold value according to the illumination condition. The threshold value used is composed of an upper limit value and a lower limit value, and a range is designated. It is a threshold to do. Therefore, when evaluating with a single threshold value, such as over-inspection that overestimates the defect and makes the lens 16 defective or erroneous inspection that makes the evaluation lens 16 non-defective by reducing the defect, Defects that occur in the difficult range of judgment are prevented, and stable and highly reliable inspection can be performed.

  In addition, the upper and lower threshold values can be set according to the number and characteristics of defective products, so inspection accuracy can be improved even when the product quality is not stable at the initial stage of production of a new product. While ensuring, it is possible to reduce the number of products that are unnecessarily re-inspected and improve inspection efficiency.

  Further, as described above, the appearance inspection apparatus 10 evaluates the defect based on the difference image that is the difference between the original image and the reference image, so that the illumination is reflected in the portion where the illumination is reflected according to the shape of the surface of the lens 16. Even a certain defect can be accurately evaluated.

  On the other hand, for lenses that require re-examination that is difficult to determine automatically, re-inspection is performed using the first to fourth original images 56, 57, 58, and 59, compared with visual inspection using a microscope. The presence / absence, degree, and type of defects are easily discriminated, and the re-inspection itself is performed quickly. Further, when re-inspection is performed using the first to fourth original images 56, 57, 58, 59, characteristics such as presence / absence, degree, and type of defects become obvious at a glance. The influence on the re-inspection is extremely small, so the inspection quality is stable.

  Further, when re-inspection is performed using the first to fourth original images 56, 57, 58, 59, when the lens 16 is evaluated as a defective product by the re-inspection, there are many defects that may occur in the future. The cause is easily identified. By controlling and analyzing the causes of defects that may increase in this way, the cause of defects such as the identification of lots with many defects and the identification of the production process that caused the defects are investigated and the lens 16 is defective. Can be prevented and the production efficiency can be improved.

  In addition, it is preferable that each part of the above-described appearance inspection apparatus 10, for example, the light emitting surface of each illumination, the CCD area sensor 23, the inspection tray 15, etc. is subjected to antireflection treatment. By applying anti-reflection processing to the light emitting surfaces of the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29, the light from each illumination becomes messy. It is possible to prevent the inspection accuracy from deteriorating due to the reflected and scattered unnecessary light incident on the CCD area sensor 23 in addition to the defects that are reflected and appear in the appearance of the lens 16. For the same reason, for example, the mask plate 36 of the appearance inspection apparatus 10 may be provided with a shutter for opening and closing the opening subjected to the antireflection treatment. In addition, when photographing the lens 16 to be inspected with the reflection type dark field illumination 27 or the reflection type bright field illumination 29, the transmission type dark field illumination 26 may be moved directly below the lens 16 to be inspected. That is, it is possible to prevent the inspection accuracy from being deteriorated by the above-described unnecessary light in the non-light emitting portion 32 of the transmissive dark field illumination 26.

  In the above-described embodiment, the appearance inspection apparatus 10 switches between the transmission type dark field illumination 26 and the transmission type bright field illumination 28 by driving the uniaxial stage 33, but is not limited thereto. And the transmissive bright field illumination 28 may use a common light emitting surface. For example, as shown in FIG. 9A, a light-shielding plate 108 having the same shape as the non-light-emitting portion 32 is rotated on the front surface of the illumination panel 106 that uniformly emits and extinguishes the entire surface. Switching between visual field illumination and transmissive bright field illumination. That is, when the light shielding plate 108 is retracted from the light emitting surface 107, the illumination panel 106 becomes the transmission type bright field illumination 28, while when the light shielding plate 108 is moved onto the light emitting surface 107, the illumination panel 106 becomes the transmission type dark field illumination 28. The field illumination 26 is obtained. Further, for example, as shown in FIG. 9B, the light shielding plate 108 may be moved horizontally on the front surface of the illumination panel 106 to switch between transmission-type dark field illumination and transmission-type bright field illumination.

  For example, as shown in FIG. 10, a so-called liquid crystal panel 116 that displays an image or the like can be suitably used as an illumination panel that is commonly used for transmissive dark field illumination and transmissive bright field illumination. In the liquid crystal panel 116, the entire surface of the light emitting surface 116 is extinguished (FIG. 10A), the entire surface of the light emitting surface 116 is illuminated (FIG. 10B), and the central portion of the light emitting surface 116 is not present. The state in which light is partially emitted (FIG. 10C) can be freely switched so as to become the light emitting unit 117. At this time, the state where the entire surface is extinguished (FIG. 10A) is a state in which the liquid crystal panel 116 is not used. In the state where the entire surface is illuminated (FIG. 10B), the liquid crystal panel 116 functions as transmissive bright field illumination. Further, the state in which light is partially emitted (FIG. 10C) functions as transmissive dark field illumination.

  Further, when the liquid crystal panel 116 is used as transmissive dark field illumination, the position and size of the non-light emitting portion 117 can be freely changed depending on the size of the lens 16 to be inspected. For example, as shown in FIG. 11A, the optimum size and shape of the non-light emitting portion 117 are determined according to the size of the lens 16 to be inspected and the shape of the curved surface, the distance between the lens 16 to be inspected and the liquid crystal panel 116, and the like. It is done. On the other hand, as shown in FIG. 11B, for example, even when the appearance of a lens 118 having a diameter larger than that of the lens 16 is inspected, the liquid crystal panel 116 has a size of the lens 118 and a curved shape. The size of the non-light emitting portion 119 is changed according to the distance between the lens 118 and the liquid crystal panel 116.

  As described above, when a common light emitting surface is used for transmissive dark field illumination and transmissive bright field illumination, the number of illumination panels can be substantially reduced. Therefore, the appearance inspection apparatus 10 is reduced in size, and further, The appearance inspection apparatus 10 can be provided at a low cost.

  When the liquid crystal panel 116 is used as transmissive dark field illumination and transmissive bright field illumination, the size and shape of the non-light emitting part can be easily and freely selected according to the characteristics of the lens to be inspected, such as the size and the shape of the surface. Can be changed.

  Note that the liquid crystal panel 116 may be an LED panel, an FED panel, an SED panel, a CRT, or the like as long as it can selectively quench a part of the light emitting surface 116.

  In the above-described embodiment, the appearance inspection apparatus 10 includes all of the transmissive dark field illumination 26, the reflective dark field illumination 27, the transmissive bright field illumination 28, and the reflective bright field illumination 29, but is not limited thereto. Absent. For example, when the appearance inspection apparatus 10 is to be provided at a lower cost, the transmission type dark field illumination 26 may not be provided, and the reflection type dark field illumination 27 may be substituted. Therefore, it is difficult to set the second threshold value, and deterioration of inspection accuracy is inevitable. Further, for example, since the appearance inspection apparatus 10 inspects the lens 16 on which the antireflection coating has been applied in advance, the reflection type bright field illumination 29 for mainly detecting the coating loss 91 is provided. However, the reflection type bright field illumination 29 is not necessarily required when the present invention is applied to the lens 16 in a state where the antireflection coating is not applied or the appearance inspection apparatus for inspecting an article which does not require the antireflection coating. . Therefore, when inspecting such an object, it is only necessary to provide three types of illumination, that is, the transmission type dark field illumination 26, the reflection type dark field illumination 27, and the transmission type bright field illumination 28. That is, the transmissive dark field illumination 26, the reflective dark field illumination 27, the transmissive bright field illumination 28, and the reflective bright field illumination 29 have different defect characteristics that can be accurately inspected. The number of illuminations provided in the appearance inspection apparatus 10 may be reduced in accordance with the characteristics of the defects generated in.

  In the above-described embodiment, the lens 16 is photographed and inspected in the order of the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29. Not exclusively. That is, the order of illumination used for imaging and inspection can be arbitrarily selected.

  In the above-described embodiment, the quality of the lens is determined at the same time as shooting under each illumination condition. However, the present invention is not limited to this, and after all shooting under the four types of illumination conditions has been completed, You may judge pass / fail.

  Furthermore, in the above-described embodiment, the first to fourth original images 56, 57, 58, 59 are registered in the database. However, the present invention is not limited to this, and the difference image is also stored in the database when the lens evaluation is good. It may be registered and used when creating a reference image. That is, the reference image creation method shown in the above-described embodiment is an example, and the present invention is not limited to this. The same inspection as in the above-described embodiment may be performed based on the reference image created by another method. Similarly, the first to fourth difference images may be registered in the database and used for reexamination.

  In the above-described embodiment, when the automatic lens evaluation is performed, the lens is evaluated based on the value defined as the defect area. However, the present invention is not limited to this, and the lens evaluation is performed based on other values. You can go. For example, the lens may be evaluated based on the characteristics of the shape of each defect such as the size and length of the defect, the perimeter, the aspect ratio, the total number of defects detected for one lens, and the like. . In order to further improve the accuracy of the inspection, it is preferable to evaluate the lens by combining these various criteria.

  In the above-described embodiment, the appearance inspection apparatus 10 that inspects the lens 16 will be described as an example. However, the inspection target article is not limited to the lens, and is preferably a transparent article that transmits light to some extent, and is opaque. It may be an article.

  In the above-described embodiment, an example in which a barcode is used as the ID 19 of the inspection tray 15 is shown, but this barcode may be a one-dimensional barcode or a two-dimensional barcode. Furthermore, the ID 19 is not limited to a barcode, and an IC chip or the like may be used.

In the above-described embodiment, a liquid crystal panel can be suitably used for any of the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29. Moreover, you may use not only this but another illumination panel and a display. For example, an LED lighting panel in which LEDs are arranged can be turned on and off at high speed, and thus is particularly preferable as illumination used for the appearance inspection apparatus 10. Further, a display using electron emission such as CRT, FET, SED may be used as illumination. That is, any operation principle can be used as long as the lens 16 to be inspected can irradiate light uniformly, and the form of illumination is not limited.

In the above-described embodiment, an example in which the appearance inspection of the lens 16 is performed is shown. However, the shape of the lens 16 to be inspected is not limited. The lens may be a meniscus lens, a biconvex lens, or a biconcave lens, and may have a spherical shape or an aspherical shape. Also, any size can be used, and a special lens such as a Fresnel lens may be used. Further, the material of the lens to be inspected is not limited to glass, and may be a known resin material, and the lens manufacturing method is not limited to the above-described embodiment, and may be manufactured by various moldings or polishing. .

In the above-described embodiment, the result of the appearance inspection of the lens 16 is registered in the database constructed in the server 76, but is not limited thereto, and may be stored in the appearance inspection apparatus 10 itself. Further, it may be output on a paper surface by a printer or the like. Further, it may be output to an inspection result display device or the like.

  In the above-described embodiment, white light is preferably used as the light emitted by each of the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29. However, the present invention is not limited thereto, and may be substantially monochromatic light in a specific wavelength range. Further, if the CCD area sensor 23 has a sensitive wavelength range, infrared light or the like may be used. Further, the transmission type dark field illumination 26, the reflection type dark field illumination 27, the transmission type bright field illumination 28, and the reflection type bright field illumination 29 may be different color illuminations.

It is a perspective view which shows the structure of an external appearance inspection apparatus roughly. It is a block diagram which shows the electrical structure of an external appearance inspection apparatus. It is a flowchart which shows the effect | action of an external appearance inspection apparatus. It is explanatory drawing which shows the defect which arises in a lens. It is explanatory drawing which shows the mode of a 1st difference image. It is explanatory drawing which shows the mode of a 2nd difference image. It is explanatory drawing which shows the mode of a 3rd difference image. It is explanatory drawing which shows the mode of a 4th difference image. It is explanatory drawing which shows a mode that an illumination panel is switched to transmissive | pervious dark field illumination and transmissive | pervious bright field illumination with a light-shielding plate. It is explanatory drawing which shows the example which uses a liquid crystal panel as transmissive | pervious dark field illumination and transmissive | pervious bright field illumination. It is explanatory drawing which shows a mode that the magnitude | size of a non-light-emitting part changes, when using a liquid crystal panel as transmissive | pervious dark field illumination.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Appearance inspection apparatus 15 Inspection tray 16 Lens 26 Transmission type dark field illumination (1st illumination means)
27 Reflective dark field illumination (second illumination means)
28 Transmission type bright field illumination (third illumination means)
29 Reflective bright field illumination (fourth illumination means)
23 CCD area sensor 36, 37 Mask plate 46 Evaluation unit 44 Difference image creation unit 43 Reference image creation unit 49 Data communication unit 76 Server 56, 57, 58, 59 Original image 61, 62, 63, 64 Reference image 66, 67, 68, 69 Difference image 71, 72, 73, 74 Threshold 106 Illumination panel 108 Light shielding plate 116 Liquid crystal panel

Claims (9)

Imaging means for imaging a subject whose appearance is to be examined;
An external appearance comprising a plurality of illumination means that uniformly illuminate the subject from different directions so that the subject and the imaging means can be switched to each other without changing the relative positions of the subject and the imaging means. Inspection device. A first illumination unit that is disposed on the opposite side of the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light transmitted through the subject does not enter the imaging unit; The appearance inspection apparatus according to claim 1, characterized in that: A second illumination unit that is disposed on the same side as the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light reflected by the subject does not enter the imaging unit; The appearance inspection apparatus according to claim 1 or 2. A third illuminating unit that is disposed on the opposite side of the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light transmitted through the subject is incident on the imaging unit; The appearance inspection apparatus according to any one of claims 1 to 3. A fourth illuminating unit that is arranged on the same side as the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light reflected by the subject is incident on the imaging unit; An appearance inspection apparatus according to any one of claims 1 to 4. Imaging means for imaging a subject whose appearance is to be examined;
A first illuminating unit that is disposed on the opposite side of the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light transmitted through the subject does not enter the imaging unit;
A second illuminating unit that is disposed on the same side as the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light reflected by the subject does not enter the imaging unit;
A third illuminating unit that is disposed on the opposite side of the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light transmitted through the subject is incident on the imaging unit;
A fourth illumination unit that is disposed on the same side as the imaging unit with respect to the subject and uniformly illuminates the subject so that illumination light reflected by the subject is incident on the imaging unit; ,
The first illuminating means, the second illuminating means, the third illuminating means, and the fourth illuminating means are provided so as to be switched with each other without changing the relative positions of the subject and the imaging means. An appearance inspection apparatus characterized by being made.   The said 1st illumination means is the illumination switched by arrange | positioning the light-shielding plate which interrupts | blocks the light from the said 3rd illumination means in the front surface of the said 1st illumination means. Visual inspection equipment.   7. The appearance inspection apparatus according to claim 4, wherein the first illumination unit is an illumination that can be switched by selectively extinguishing a part of the light emitting surface of the third illumination unit.   The first illumination means is disposed at a position facing the imaging means when the subject is illuminated by the second illumination means or the fourth illumination means. Appearance inspection apparatus according to crab.

Images