JP2020003343A - Defect inspection device and defect inspection method - Google Patents

Abstract

To detect a defect of a test object with high accuracy using ring-shaped illumination light, without the need for switching the illumination light in correspondence to the type of test object.SOLUTION: A flat panel display device 10 displays a portion of ring-shaped illumination light with which a light permeable transparent or semi-transparent test object 1 is irradiated. A control device 80 divides the ring-shaped illumination light into a plurality of sections and causes each of the divided sections to be displayed in order by the flat panel display device 10. An image acquisition device (camera 40) acquires, from the flat panel display device 10, an image of the test object 1 irradiated with light of each of the divided sections of the ring-shaped illumination light and outputs an image signal. An image processing device 50 processes each image signal outputted from the image acquisition device (camera 40), synthesizes a plurality of images of the test object 1, and detects a defect of the test object 1 from the synthesized image.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a defect inspection apparatus and a defect inspection method for inspecting whether or not a defect such as a scratch or a foreign substance is present on the surface or inside of an object to be inspected, and in particular, a ring-shaped illumination light as dark field illumination. The present invention relates to a defect inspection apparatus and a defect inspection method used.

  For example, an eyeglass lens is a product of many kinds in a small quantity because the shape, curvature, refractive index, transmittance, gradation coating and the like are different depending on its use and design, and the specification is determined by a combination thereof. Conventionally, a visual inspection by an inspector has been mainly used to inspect whether or not a defect such as a scratch, a foreign substance, or an uneven coating exists on the surface or inside of the glasses lens. However, the visual inspection largely depends on the experience and intuition of the inspector, so that the accuracy varies, and the labor cost of the inspector causes an increase in the cost of the lens. Therefore, automation of the inspection has been desired.

  When attempting to automate the inspection of a lens for defects using an image acquisition device such as a camera, it is necessary to change the settings of the illumination device and the image acquisition device for each type of lens. On the other hand, Patent Document 1 includes a plurality of LEDs and a plurality of polarizers having at least two types of different polarization directions, and divides the plurality of LEDs into a plurality of LED groups and drives the plurality of LEDs to measure. An illumination device and an optical device that can be easily adjusted to obtain high detection sensitivity regardless of the state of an object and that can prevent generation of illumination light that causes deterioration in detection sensitivity are disclosed.

JP 2012-240881 A

  As described in paragraphs 0002 and 0003 of Patent Document 1, in an optical device such as an optical microscope, an optical measuring device, and an image observation device, illumination light is applied from a direction oblique to an observation direction and a detection direction. As a method of irradiating light, a ring illumination device is often used. Observation of scattered light from the object to be inspected, dark-field observation using a ring illumination device is very effective for detecting defects such as lens scratches and foreign substances with high accuracy. is there. However, depending on the angle of the curved surface of the lens, reflection of the illumination light may occur on the surface of the lens, and the portion where the reflected light is generated may be inspected using another illumination device, or disclosed in Japanese Patent Application Laid-Open No. H10-163,873. It is necessary to select an LED group to be driven from a plurality of LED groups, as described in (1).

  An object of the present invention is to detect a defect of an inspection object with high accuracy without using a ring-shaped illumination light and switching the illumination light according to the type of the inspection object.

  The defect inspection apparatus of the present invention is applied to a transparent or translucent inspection object that transmits light, a flat panel display device that displays a part of ring-shaped illumination light, and a plurality of ring-shaped illumination lights. A control device that divides each of the divided sections and sequentially displays each of the divided sections on a flat panel display device, and an inspection target in which the light of each divided section of the ring-shaped illumination light is emitted from the flat panel display device. An image acquisition device that acquires an image of an object and outputs an image signal; and processes each image signal output from the image acquisition device to synthesize a plurality of images of the inspected object. An image processing device for detecting a defect of the inspection object.

  Further, in the defect inspection method of the present invention, the ring-shaped illumination light is divided into a plurality of sections, the divided sections are sequentially displayed on a flat panel display device, and the light of each section is transmitted. By irradiating the transparent or translucent inspection object in order, the image acquisition device irradiates the light of each divided section of the ring-shaped illumination light, acquires an image of the inspection object, and outputs an image signal. Processing each image signal output by the image acquisition device, synthesizes a plurality of images of the inspection object, and detects a defect of the inspection object from the synthesized image.

  The ring-shaped illumination light is divided into a plurality of sections, and each of the divided sections is sequentially displayed on a flat panel display device, and the light of each section is sequentially irradiated on the inspection object. Since an image of the object to be inspected, which is obtained by irradiating the light of each of the divided sections of the ring-shaped illumination light, is obtained and an image signal is output, there is no need to switch the illumination light according to the type of the object to be inspected. Then, each image signal output by the image acquisition device is processed, a plurality of images of the inspection object are combined, and a defect of the inspection object is detected from the combined image. Defects of the inspection object are detected with high accuracy.

  In addition, since the divided sections of the ring-shaped illumination light are displayed on the flat panel display device, the resolution is higher than when the LED group and the diffuser arranged in a ring are used, and the leakage from the diffuser is increased. The combined light is prevented from being redundantly added during the synthesis of the images, and the defect of the inspection object is detected with higher accuracy.

  Alternatively, the defect inspection apparatus of the present invention generates a light that is emitted to a transparent or translucent inspection object that transmits light, a plurality of LED groups arranged in a ring shape, and light generated from the LED group. A diffusion plate to be diffused, a control device that divides the LED group into a plurality of sections, and sequentially turns on the LEDs in each of the divided sections, and light from the LEDs in each of the divided sections of the LED group is irradiated through the diffusion plate. An image acquisition device that acquires an image of an inspection object and outputs an image signal, processes each image signal output from the image acquisition device, synthesizes a plurality of images of the inspection object, and synthesizes the combined image. And an image processing device for detecting a defect of the inspection object.

  Further, the defect inspection method of the present invention arranges a plurality of LED groups in a ring shape, divides the LED group arranged in a ring shape into a plurality of sections, and turns on the LEDs in each of the divided sections in order. The light of the LED of the section is sequentially irradiated to the transparent or translucent object through which light is transmitted through the diffusion plate, and the light of the LED of each divided section is irradiated through the diffusion plate by the image acquisition device. An image of the inspection object is acquired, an image signal is output, each image signal output by the image acquisition device is processed, a plurality of images of the inspection object are combined, and a defect of the inspection object is obtained from the combined image. Is detected.

  A plurality of LED groups are arranged in a ring shape, the LED group arranged in a ring shape is divided into a plurality of sections, the LEDs in each of the divided sections are sequentially turned on, and the light of the LEDs in each section is passed through the diffusion plate. Irradiates the inspection object in order, irradiates the LED light of each divided section through the diffusion plate by the image acquisition device, acquires an image of the inspection object, and outputs an image signal. There is no need to switch the illumination light according to the type of the illumination light. Then, each image signal output by the image acquisition device is processed, a plurality of images of the inspection object are synthesized, and a defect of the inspection object is detected from the synthesized image. The defect of the object to be inspected is detected with high accuracy by using the ring-shaped illumination light by the method.

  Further, the defect inspection apparatus according to the present invention, when the image processing apparatus arranges each image signal for each pixel at the same position in order of size for each image signal output from the image acquisition apparatus, the m-th Each image signal after (m ≧ 2) is added to synthesize a plurality of images of the inspection object.

  Further, the defect inspection method according to the present invention is characterized in that, for each image signal output from the image acquisition device, when each image signal is arranged in order of size for each pixel at the same position, the m-th (m ≧ 2) or more from the largest one Are added to synthesize a plurality of images of the inspection object.

  When each image signal output from the image acquisition device is arranged in order of size for each pixel at the same position, the m-th (m ≧ 2) or more image signals from the largest are added, and Since a plurality of images of the inspection object are combined, the object to be inspected can be irradiated by irradiating any one of the sections of the ring-shaped illumination light or irradiating the LED light of any one of the sections of the ring-shaped LED group. Even if transmitted or reflected light is generated from an object and a pixel with a very large signal intensity is generated, the image signal of the pixel with a very large signal intensity is not added, and the effect of the transmitted or reflected light is removed. . Therefore, the defect of the inspection object can be detected without using another illumination device.

  Further, in the defect inspection apparatus of the present invention, when a flat panel display apparatus is used, the image processing apparatus detects a pixel whose signal intensity is equal to or more than a predetermined value from each image signal output from the image acquisition apparatus, and controls the image processing apparatus. The apparatus sets the inner diameter of the ring-shaped illumination light to a size at which transmitted light is generated from the object to be inspected, and based on the detection result of the image processing apparatus, sets until the pixel whose signal intensity is equal to or more than a predetermined value disappears. The inner diameter of the ring-shaped illumination light is enlarged.

  Further, in the defect inspection method of the present invention, when a flat panel display device is used, the inner diameter of the ring-shaped illumination light is set to a size at which transmitted light is generated from the inspection object, and each image output by the image acquisition device is set. From the image signal, a pixel whose signal intensity is equal to or higher than a predetermined value is detected, and until the pixel whose signal intensity is equal to or higher than the predetermined value disappears, the inner diameter of the set ring-shaped illumination light is enlarged. It is characterized by combining images.

  The ring-shaped illumination light is desirably provided at a position close to the object to be inspected so that more scattered light is generated from the object within a range where transmitted light is not generated from the object to be inspected. The inner diameter of the ring-shaped illumination light is set to a size at which transmitted light is generated from the inspection object, and from each image signal output by the image acquisition device, a pixel whose signal intensity is equal to or greater than a predetermined value is detected, and the signal intensity is detected. Until there is no pixel whose value is equal to or larger than a predetermined value, the set inner diameter of the ring-shaped illumination light is enlarged, so that the ring-shaped illumination light is positioned closer to the inspection object within a range in which no transmitted light is generated from the inspection object. Is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the defect of a test object can be detected with high precision, without using a ring-shaped illumination light and switching illumination light according to the kind of a test object.

  Furthermore, when the divided sections of the ring-shaped illumination light are displayed on a flat panel display device, the resolution can be increased as compared with a case where a ring-shaped LED group and a diffusion plate are used, and the diffusion plate It is possible to prevent the light leaked from from being redundantly added at the time of synthesizing the images, so that the defect of the inspection object can be detected with higher accuracy.

  Furthermore, for each image signal output by the image acquisition device, when the image signals are arranged in order of magnitude for each pixel at the same position, the m-th (m ≧ 2) or later image signals from the largest are added. By combining a plurality of images of the object to be inspected, irradiation of light in any of the sections of the ring-shaped illumination light, or irradiation of light of the LEDs in any of the sections of the LED group arranged in a ring can be performed. Even if transmitted light or reflected light is generated from the inspection object and a pixel having a very large signal intensity is generated, the influence of the transmitted light or the reflected light is not added without adding the image signal of the pixel having a very large signal intensity. Can be removed. Therefore, it is possible to detect a defect of the inspection object without using another illumination device.

  Further, when a flat panel display device is used, the inner diameter of the ring-shaped illumination light is set to a size at which transmitted light is generated from the inspection object, and the signal intensity is determined from each image signal output by the image acquisition device. By detecting pixels having a value equal to or greater than the value and expanding the inner diameter of the set ring-shaped illumination light until there is no pixel having a signal intensity equal to or greater than a predetermined value, the ring-shaped illumination light is transmitted from the object to be inspected. Within the range in which does not occur, the object is brought closer to the inspection object, and more scattered light is generated from the inspection object, so that a defect of the inspection object can be detected with higher accuracy.

1 is a diagram illustrating a schematic configuration of a defect inspection device according to an embodiment of the present invention. It is a figure showing an example of illumination light of a ring shape. It is a figure showing an example of each section of ring-shaped illumination light. It is a figure explaining operation of a mobile device. It is a figure explaining generation | occurrence | production of the scattered light from a test object. It is a figure which shows the example of the image of the to-be-inspected object irradiated with the light of each division of ring-shaped illumination light. 5 is a flowchart illustrating an example of an operation of the defect inspection device according to the embodiment of the present invention. FIG. 9 is a diagram illustrating an image combining process. It is a figure showing an example of the combined picture. 6 is a flowchart illustrating another example of the operation of the defect inspection device according to the embodiment of the present invention. FIG. 11A is a top view of an illumination device of a defect inspection device according to another embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along the line BB of FIG. 11A. It is a figure which shows the example of LED of each division | segmentation divided. 9 is a flowchart showing an operation of the defect inspection device according to another embodiment of the present invention.

[Embodiment]
(First Embodiment)
FIG. 1 is a diagram showing a schematic configuration of a defect inspection apparatus according to one embodiment of the present invention. The defect inspection device 100 includes a holder 2, a flat panel display device 10, a moving device 20, a condenser lens 30, a camera 40, an image processing device 50, a memory 60, a display device 70, and a control device 80. . The holder 2 sandwiches and holds the edge of the transparent or translucent inspection object 1 that transmits light from three or more directions. Note that the holder 2 may be configured to hold the plurality of inspection objects 1 and move with respect to the condenser lens 30 and the camera 40. Alternatively, the configuration may be such that the holder 2 holds the plurality of inspection objects 1 and the condenser lens 30 and the camera 40 move with respect to the holder 2.

  The flat panel display device 10 includes a liquid crystal display device, a plasma display device, an organic EL (Electroluminescence) display device, a projector, and the like, and displays a part of the ring-shaped illumination light under the control of the control device 80. FIG. 2 is a diagram illustrating an example of ring-shaped illumination light. In FIG. 2, a ring-shaped white portion floating on a black background is the ring-shaped illumination light 11. In addition, the ring-shaped illumination light is not limited to the circular outer and inner circumferences, and the outer and inner circumferences may be elliptical or rectangular or conform to the shape of the test object 1 according to the shape of the test object 1. May be used.

  In FIG. 1, the control device 80 divides the ring-shaped illumination light into a plurality of sections, and causes the flat panel display device 10 to sequentially display the divided sections. FIG. 3 is a diagram illustrating an example of each section of the ring-shaped illumination light displayed on the flat panel display device 10. This example shows a case where the ring-shaped illumination light 11 shown in FIG. 2 is equally divided in the circumferential direction into eight sections shown in FIGS. The number of sections is not limited to this example, and the ring-shaped illumination light may be divided into seven or less or nine or more. In addition, the form of division is not limited to the case where the ring-shaped illumination light is divided in the circumferential direction, and the light of each section is incident on the inspection object 1 from a different direction or at a different angle. What is necessary is just to divide.

  In FIG. 1, a moving device 20 moves the flat panel display device 10 up and down. FIG. 4 is a diagram illustrating the operation of the mobile device. The moving device 20 includes a table 21, a guide 22, and an elevating mechanism 23. The table 21 has the flat panel display device 10 mounted thereon and moves along the guide 22 in the vertical direction in the drawing. The elevating mechanism 23 raises and lowers the table 21 to move the flat panel display device 10 in a direction approaching the inspection object 1 or in a direction moving away from the inspection object 1. As a result, as shown in FIGS. 4A and 4B, the distance D between the flat panel display device 10 and the inspection object 1 changes.

  In FIG. 1, a condenser lens 30 collects light emitted from the flat panel display device 10 and transmitted through the inspection object 1. As the condenser lens 30, a lens having an entrance pupil at infinity and a principal ray parallel to the optical axis is used. The camera 40 has a two-dimensional sensor such as a CCD or a CMOS, receives light condensed by the condensing lens 30, acquires an image of the inspection object 1, and outputs an image signal of the acquired image. .

  In the embodiment shown in FIG. 1, the flat panel display device 10 is provided on the opposite side of the inspection object 1 from the camera 40 (below the inspection object 1). However, the flat panel display device 10 is provided above the inspection object 1 similarly to the camera 40, and the mirror that reflects a part of the ring-shaped illumination light displayed on the flat panel display device 10 is positioned below the inspection object 1. May be provided.

  The image processing device 50 processes the image signal output from the camera 40 under the control of the control device 80, synthesizes a plurality of images of the inspected object 1 acquired by the camera 40, and A defect of the inspection object 1 is detected. The memory 60 stores an image signal output from the camera 40, an image signal processed by the image processing device 50, and information on a defect of the inspection object 1 detected by the image processing device 50. The display device 70 displays the image acquired by the camera 40, the image processed by the image processing device 50, and the position, size, shape, and the like of the defect of the inspection object 1 detected by the image processing device 50. . The control device 80 controls the flat panel display device 10, the moving device 20, the image processing device 50, the memory 60, and the display device 70.

  FIG. 5 is a diagram illustrating generation of scattered light from the inspection object. The light R from each section of the ring-shaped illumination light displayed on the flat panel display device 10 enters the inspection object 1 from the oblique lower side of the inspection object 1 in the drawing. Then, each time the light transmitted inside the inspection object 1 is repeatedly reflected inside the inspection object 1, a part of the light is emitted to the outside of the inspection object 1 as scattered light S. The scattered light S tends to be generated more on the opposite side of the center line C passing through the center of the inspected object 1 from the position where the light R from each section of the ring-shaped illumination light is incident on the inspected object 1. It is in.

  FIG. 6 is a diagram illustrating an example of an image of the inspection object irradiated with light of each section of the ring-shaped illumination light. 6 (a) to 6 (h) correspond to FIGS. 3 (a) to 3 (h), and the light of each section of the ring-shaped illumination light shown in FIGS. 3 (a) to 3 (h) is irradiated. At this time, the image of the inspection object 1 acquired by the camera 40 and displayed on the display device 70 is schematically shown. Since the scattered light tends to be generated on the side opposite to the position where the light from each section of the ring-shaped illumination light is incident on the inspection object 1, each of the images in FIGS. 3 (a) to 3 (h), each section of the ring-shaped illumination light is slightly brighter on the opposite side across the center of the inspection object 1.

  FIG. 7 is a flowchart showing an example of the operation of the defect inspection device according to the embodiment of the present invention. First, the control device 80 causes the flat panel display device 10 to display the entire ring-shaped illumination light (step 101). Then, the control device 80 moves the flat panel display device 10 up and down by the moving device 20, and determines the distance between the flat panel display device 10 and the test object 1 according to the size and the focal length of the test object 1. Adjust (step 102).

  Next, the control device 80 causes the flat panel display device 10 to display one section of the ring-shaped illumination light (step 103). The camera 40 acquires an image of the inspection object 1 and outputs an image signal (Step 104). Subsequently, the control device 80 determines whether or not all sections of the ring-shaped illumination light have been displayed on the flat panel display device 10 (step 105). If not, the sections are changed. (Step 106), and return to Step 103.

  When the display of all the sections is completed, the image processing device 50 processes each image signal output from the camera 40 under the control of the control device 80 to synthesize a plurality of images of the inspection object 1 (step). 107). At this time, when each image signal output from the camera 40 is arranged in order of size for each pixel at the same position with respect to each image signal output from the camera 40, the m-th (m ≧ 2) and subsequent m-th from the largest one Each image signal is added to synthesize a plurality of images of the inspection object 1.

  FIG. 8 is a diagram illustrating the image combining process. When the ring-shaped illumination light is divided into eight sections shown in FIGS. 3A to 3H and the light of each section is sequentially irradiated on the inspection object 1, the signal intensity of a pixel at a certain position becomes higher. , N = 1 to 8 in FIG. The image processing device 50 rearranges these values in order of magnitude, and adds the values of the m-th (m ≧ 2) and subsequent image signals. For example, when m = 4, the equation is as shown in (A).

  When the image signals output from the camera 40 are arranged in order of magnitude for each pixel at the same position, the m-th (m ≧ 2) or later image signals from the largest are added, and the inspection is performed. Since a plurality of images of the object 1 are synthesized, transmitted light or reflected light is generated from the inspected object 1 by irradiation of light in any of the sections of the ring-shaped illumination light, and pixels having a very large signal intensity are generated. However, the image signal of the pixel having a very large signal intensity is not added, and the influence of the transmitted light or the reflected light is removed. Therefore, the defect of the inspection object 1 is detected without using another illumination device.

  In FIG. 8, for example, the reason for setting m = 4 is that when transmitted light or reflected light is generated by irradiation of light in one of the divided sections of the ring-shaped illumination light, the left and right adjacent to that section There is a possibility that a pixel having a large signal intensity may be generated even by the irradiation of the light of the section (3). Therefore, the image signal of the pixel of the image when the light of the three sections including the adjacent left and right sections is irradiated is excluded. It is. However, m may be 2, 3, or 5 or more.

  In addition, for each image signal output from the camera 40, when the image signals are arranged in order of size for each pixel at the same position, if a predetermined number of image signals are not added from the smaller one, The effect of noise generated in the image signal can be removed. Therefore, it is possible to detect the defect of the inspection object 1 with higher accuracy.

  In FIG. 7, next, the image processing device 50 detects a defect of the inspection object 1 from the combined image (Step 108). The control device 80 displays the detection result of the image processing device 50 on the display device (Step 109).

  FIG. 9 is a diagram illustrating an example of a combined image. FIG. 9 schematically shows an image obtained by synthesizing the images of the inspection object 1 shown in FIGS. 6A to 6H, similarly to FIG. 6. In FIG. 9, the round shape of the inspection object 1 is displayed as whitish, but in an actual dark-field image, it is observed as gray (gray) having a slightly higher brightness against a black background. 9 does not show the defect of the inspection object 1, but if there is a defect such as a scratch or a foreign substance on the surface or inside of the inspection object 1, the intensity of the scattered light at the position where the defect exists is reduced. It becomes stronger than other parts, and the brightness of the pixel at that position becomes higher. The image processing device 50 detects a position, a size, a shape, and the like of a defect of the inspection object 1 by detecting an image signal whose signal intensity is equal to or more than a predetermined threshold from the image signal of the synthesized image. .

  The ring-shaped illumination light is divided into a plurality of sections, and each of the divided sections is sequentially displayed on the flat panel display device 10, and the light of each section is sequentially irradiated on the inspection object 1. Since an image of the inspection object 1 obtained by irradiating the light of each divided section of the ring-shaped illumination light is obtained and an image signal is output, it is not necessary to switch the illumination light according to the type of the inspection object 1. Absent. Then, each image signal output by the camera 40 is processed, a plurality of images of the inspected object 1 are synthesized, and a defect of the inspected object 1 is detected from the synthesized image. In addition, the defect of the inspection object 1 is detected with high accuracy.

  Further, since the divided sections of the ring-shaped illumination light are displayed on the flat panel display device 10, the resolution is higher than in the second embodiment using the LED group and the diffusion plate arranged in a ring, In addition, light leaked from the diffusion plate is prevented from being redundantly added at the time of combining images, and a defect of the inspection object 1 is detected with higher accuracy.

  FIG. 10 is a flowchart illustrating another example of the operation of the defect inspection device according to the embodiment of the present invention. First, the control device 80 moves the flat panel display device 10 up and down by the moving device 20, and determines the distance between the flat panel display device 10 and the test object 1 according to the size and the focal length of the test object 1. Adjust (step 201). Next, the control device 80 sets the inner diameter of the ring-shaped illumination light (step 202-1). At this time, the control device 80 sets the inner diameter of the ring-shaped illumination light to a size at which transmitted light is generated from the inspection object 1.

  Next, the control device 80 causes the flat panel display device 10 to display the entire ring-shaped illumination light (step 202-2). The image processing device 50 detects, from the image signal output from the camera 40, a pixel whose signal strength is equal to or more than a predetermined value under the control of the control device 80. It is determined whether or not there is a pixel whose signal strength is equal to or greater than a predetermined value (step 202-3).

  If there is a pixel whose signal intensity is equal to or greater than the predetermined value, the control device 80 enlarges the inner diameter of the ring-shaped illumination light set in step 202-1 by a certain value (step 202-4), and then proceeds to step 202- Return to 1. Steps 202-1 to 202-4 are repeated until there is no pixel whose signal strength is equal to or more than the predetermined value.

  When there is no pixel whose signal strength is equal to or more than the predetermined value, the subsequent processing of steps 203 to 209 is the same as the processing of steps 103 to 109 in FIG.

  The ring-shaped illumination light is desirably provided at a position close to the inspection object 1 so that scattered light is more generated from the inspection object 1 within a range in which transmitted light is not generated from the inspection object 1. The inner diameter of the ring-shaped illumination light is set to a size at which transmitted light is generated from the inspection object 1, and a pixel whose signal intensity is equal to or greater than a predetermined value is detected from each image signal output by the camera 40, and the signal intensity is determined. Until there is no pixel whose value is equal to or greater than a predetermined value, the set inner diameter of the ring-shaped illumination light is enlarged, so that the ring-shaped illumination light is applied to the object 1 within a range in which no transmitted light is generated from the object 1. It is provided in a close position.

(Effects of the First Embodiment)
According to the first embodiment described above, the following effects can be obtained.
(1) Using the ring-shaped illumination light, the defect of the inspection object 1 can be detected with high accuracy without switching the illumination light according to the type of the inspection object 1.

(2) Further, by displaying each of the divided sections of the ring-shaped illumination light on the flat panel display device 10, the resolution is higher than that in the second embodiment using the ring-shaped LED group and the diffusion plate. Can be increased, and the light leaked from the diffusion plate can be prevented from being added redundantly at the time of combining images, so that the defect of the inspection object 1 can be detected with higher accuracy. be able to.

(3) Further, for each image signal output by the camera 40, when the image signals are arranged in order of size for each pixel at the same position, the m-th (m ≧ 2) and subsequent image signals from the largest are added. Then, by synthesizing a plurality of images of the test object 1, transmitted light or reflected light is generated from the test object 1 by irradiation of light in any of the sections of the ring-shaped illumination light, and the signal intensity is reduced. Even if a very large pixel is generated, it is possible to eliminate the influence of the transmitted light or the reflected light without adding the image signal of the pixel having the very large signal intensity. Therefore, it is possible to detect a defect of the inspection object 1 without using another illumination device.

(4) Further, the inner diameter of the ring-shaped illumination light is set to a size at which transmitted light is generated from the inspection object 1, and from each image signal output by the camera 40, a pixel whose signal intensity is equal to or more than a predetermined value is determined. By detecting and increasing the inner diameter of the set ring-shaped illumination light until there is no pixel whose signal strength is equal to or more than the predetermined value, the ring-shaped illumination light is transmitted within a range where transmitted light is not generated from the inspection object 1. By bringing the object 1 closer to the inspection object 1 and generating more scattered light from the inspection object 1, it is possible to detect the defect of the inspection object 1 with higher accuracy.

(Second embodiment)
As another embodiment of the present invention, instead of the flat panel display device 10 of FIG. 1, a lighting device having an LED group and a diffusion plate arranged in a ring shape may be used. FIG. 11A is a top view of an illumination device of a defect inspection device according to another embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along the line BB of FIG. 11A. The lighting device 90 includes a case 91, a group of a plurality of LEDs 92, and a diffusion plate 93.

  In FIG. 11A, the case 91 has a ring shape when viewed from above, and a plurality of LED 92 groups indicated by broken lines are arranged in the case 91 in a ring shape. In FIG. 11B, the inner wall of the case 91 is mirror-processed to reflect light generated by the plurality of LEDs 92. A diffusion plate 93 having a concave surface 93a is attached to the upper surface of the case 91. The diffusion plate 93 diffuses the light generated by the plurality of LEDs 92, thereby preventing the shape of each LED 92 from being reflected on the surface of the inspection object 1.

  The control device 80 of FIG. 1 divides a plurality of LED 92 groups arranged in a ring shape into a plurality of sections, and sequentially turns on the LEDs 92 in each of the divided sections. FIG. 12 is a diagram illustrating an example of the LED of each divided section. This example shows a case where a plurality of LED 92 groups arranged in a ring shape indicated by broken lines in FIG. 12A are equally divided into eight sections 90a to 90h in the circumferential direction of the ring. The number of sections is not limited to this example, and a plurality of LED 92 groups arranged in a ring shape may be divided into seven or less or nine or more. In addition, the form of division is not limited to the case where a plurality of LED 92 groups arranged in a ring shape are divided in the circumferential direction of the ring, and the light of the LEDs of each section enters the inspection object 1 from different directions. Or may be divided so as to be incident at different angles.

  FIG. 13 is a flowchart showing the operation of the defect inspection apparatus according to another embodiment of the present invention. First, the control device 80 turns on the entire group of LEDs 92 arranged in a ring (step 301). Then, the control device 80 moves the illumination device 90 up and down by the moving device 20, and adjusts the distance between the illumination device 90 and the inspection object 1 according to the size and the focal length of the inspection object 1 (step). 302).

  Next, the control device 80 turns on the LED 92 in one of the divided sections of the LED 92 group (step 303). The camera 40 acquires an image of the inspection object 1 and outputs an image signal (Step 304). Subsequently, the control device 80 determines whether or not the LEDs 92 of all sections have been turned on (step 305). If not, the section is changed (step 306), and the process returns to step 303.

  When the lighting of the LEDs 92 in all the sections is completed, the image processing device 50 processes each image signal output from the camera 40 and synthesizes a plurality of images of the inspection object 1 under the control of the control device 80. (Step 307). The method of the combining process is the same as that of the first embodiment described with reference to FIG.

  When the image signals output from the camera 40 are arranged in order of magnitude for each pixel at the same position, the m-th (m ≧ 2) or later image signals from the largest are added, and the inspection is performed. Since a plurality of images of the object 1 are synthesized, transmitted light or reflected light is generated from the inspection object 1 by irradiating light from the LEDs 92 in any of the groups of the LEDs 92 arranged in a ring shape, and the signal intensity is extremely high. Even if a large pixel is generated, the image signal of the pixel having a very large signal intensity is not added, and the influence of the transmitted light or the reflected light is removed. Therefore, the defect of the inspection object 1 is detected without using another illumination device.

  Next, the image processing device 50 detects a defect of the inspection object 1 from the combined image (Step 308). The control device 80 displays the detection result of the image processing device 50 on the display device (Step 309).

  A plurality of groups of LEDs 92 are arranged in a ring shape, the group of LEDs 92 arranged in a ring shape is divided into a plurality of sections, and the LEDs 92 in each of the divided sections are sequentially turned on, and the light of the LEDs 92 in each section is diffused by the diffusion plate 93. Through the diffuser 93, the image of the inspected object 1 is obtained by irradiating the light of the LED 92 of each divided section through the diffusion plate 93, and an image signal is output. It is not necessary to switch the illumination light according to the type of the inspection object 1. Then, each image signal output from the camera 40 is processed, a plurality of images of the inspected object 1 are synthesized, and a defect of the inspected object 1 is detected from the synthesized image. The defect of the inspection object 1 is detected with high accuracy using the ring-shaped illumination light of the group.

(Effect of Second Embodiment)
According to the second embodiment described above, the following effects can be obtained.
(1) It is possible to detect a defect of the inspection object 1 with high accuracy without using the illumination light of the ring 92 arranged in a ring shape and switching the illumination light according to the type of the inspection object 1. it can.

(2) Further, when the image signals output from the camera 40 are arranged in order of size for each pixel at the same position, the m-th (m ≧ 2) and subsequent image signals are added from the largest one. Then, by synthesizing a plurality of images of the inspection object 1, transmitted light or reflected light is generated from the inspection object 1 by irradiation of light of the LEDs 92 in any of the groups of the LEDs 92 arranged in a ring shape. Even if a pixel having a very high signal intensity is generated, the influence of the transmitted light or the reflected light can be removed without adding the image signal of the pixel having the extremely high signal intensity. Therefore, it is possible to detect a defect of the inspection object 1 without using another illumination device.

  INDUSTRIAL APPLICABILITY The present invention can be applied not only to defect inspection of optical components such as lenses, but also to defect inspection of transparent or translucent objects such as pipes and glass that transmit light.

DESCRIPTION OF SYMBOLS 1 Inspection object 2 Holder 10 Flat panel display device 11 Ring-shaped illumination light 20 Moving device 21 Table 22 Guide 23 Elevating mechanism 30 Condensing lens 40 Camera 50 Image processing device 60 Memory 70 Display device 80 Control device 90 Lighting device 91 Case 92 LED
93 Diffusion plate 100 Defect inspection device

Claims (10)

Irradiated on a transparent or translucent test object that transmits light, a flat panel display device that displays a part of ring-shaped illumination light,
A control device that divides the ring-shaped illumination light into a plurality of sections, and the divided sections are sequentially displayed on the flat panel display device,
From the flat panel display device, the light of each of the divided sections of the ring-shaped illumination light is irradiated, to obtain an image of the inspection object, an image acquisition device that outputs an image signal,
An image processing device that processes each image signal output from the image acquisition device, combines a plurality of images of the inspection object, and detects a defect of the inspection object from the combined image. A defect inspection apparatus characterized by the above-mentioned. The image processing apparatus is configured such that, for each image signal output from the image acquisition apparatus, for each pixel at the same position, when arranging the image signals in order of magnitude, each of the m-th (m ≧ 2) and subsequent The defect inspection apparatus according to claim 1, wherein a plurality of images of the inspection object are synthesized by adding image signals. The image processing device detects, from each image signal output from the image acquisition device, a pixel whose signal intensity is equal to or greater than a predetermined value,
The control device sets the inner diameter of the ring-shaped illumination light to a size at which transmitted light is generated from the inspection object, and based on a detection result of the image processing device, a pixel whose signal intensity is equal to or more than a predetermined value. 3. The defect inspection apparatus according to claim 1, wherein the set inner diameter of the ring-shaped illumination light is enlarged until no longer exists. 4. A plurality of LED groups arranged in a ring shape, which emit light to be transmitted to a transparent or translucent inspection object that transmits light,
A diffusion plate for diffusing light generated from the LED group;
A control device that divides the LED group into a plurality of sections, and sequentially turns on the LEDs in each of the divided sections;
An image acquisition device that acquires an image of the object to be inspected, in which the light of the LEDs in each of the divided sections of the LED group is irradiated through the diffusion plate, and outputs an image signal,
An image processing device that processes each image signal output from the image acquisition device, combines a plurality of images of the inspection object, and detects a defect of the inspection object from the combined image. A defect inspection apparatus characterized by the above-mentioned. The image processing apparatus is configured such that, for each image signal output from the image acquisition apparatus, for each pixel at the same position, when arranging the image signals in order of magnitude, each of the m-th (m ≧ 2) and subsequent The defect inspection apparatus according to claim 4, wherein a plurality of images of the inspection object are synthesized by adding image signals. Divide the ring-shaped illumination light into multiple sections,
Each of the divided sections is sequentially displayed on a flat panel display device, and the light of each section is sequentially radiated to a transparent or translucent test object that transmits light,
By the image acquisition device, irradiating the light of each divided section of the ring-shaped illumination light, to acquire an image of the inspection object, output an image signal,
A defect inspection method, comprising processing each image signal output by the image acquisition device, synthesizing a plurality of images of the inspection object, and detecting a defect of the inspection object from the synthesized image. For each image signal output by the image acquisition device, for each pixel at the same position, when arranging the image signals in order of magnitude, adding the m-th (m ≧ 2) or later image signals from the largest, The defect inspection method according to claim 6, wherein a plurality of images of the inspection object are combined. The inner diameter of the ring-shaped illumination light is set to a size at which transmitted light is generated from the inspection object,
From each image signal output by the image acquisition device, a pixel whose signal intensity is equal to or greater than a predetermined value is detected,
Until there is no pixel whose signal intensity is equal to or greater than a predetermined value, after expanding the set inner diameter of the ring-shaped illumination light,
The defect inspection method according to claim 6, wherein a plurality of images of the inspection object are combined. Arrange a plurality of LED groups in a ring shape,
Dividing the LED group arranged in a ring shape into a plurality of sections,
The LEDs of each of the divided sections are sequentially turned on, and the light of the LEDs of each section is sequentially irradiated on a transparent or translucent test object that transmits light through a diffusion plate,
The image acquisition device irradiates the light of the LED of each divided section through the diffusion plate, acquires an image of the inspection object, outputs an image signal,
A defect inspection method, comprising processing each image signal output by the image acquisition device, synthesizing a plurality of images of the inspection object, and detecting a defect of the inspection object from the synthesized image. For each image signal output by the image acquisition device, for each pixel at the same position, when arranging the image signals in order of magnitude, adding the m-th (m ≧ 2) or later image signals from the largest, The defect inspection method according to claim 9, wherein a plurality of images of the inspection object are combined.

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