JP5625901B2 - Defect inspection method for glass substrate, defect inspection apparatus for glass substrate, and method for manufacturing glass substrate - Google Patents

Description

  The present invention relates to a glass substrate defect inspection method and a glass substrate defect inspection device for inspecting the presence or absence of defects of the glass substrate, and a glass substrate having an inspection process using the defect inspection method or the defect inspection device. Regarding the method.

  In recent years, glass substrates have been used for various purposes. For example, a hard disk drive (HDD) which is an external storage device such as a personal computer (PC) is equipped with a magnetic recording medium known as a computer storage, and a glass substrate is used as a substrate for the magnetic recording medium. It has been.

  When such a glass substrate is manufactured, defects such as scratches may be formed on the main plane of the glass substrate in the glass substrate manufacturing process. If a glass substrate on which defects such as scratches are formed is put into a polishing apparatus in a polishing process, the glass substrate may be damaged during polishing. Further, when the scratch formed on the main plane of the glass substrate is deep and the scratch cannot be sufficiently removed in the polishing process, the scratch remains on the main plane of the glass substrate product completed as a final product. If a glass substrate with scratches remaining on the main plane is used for a magnetic recording medium or the like, the performance of the magnetic recording medium or the like may not be exhibited sufficiently.

  Therefore, defects such as scratches formed on the main plane of the glass substrate need to be discovered early, and the glass substrate is inspected for defects in the glass substrate manufacturing process. Such a defect inspection is performed visually, for example. Moreover, as a method other than visual observation, a technique has been proposed in which light is applied to a glass substrate, reflected light of the irradiated light is imaged with an imaging device, and the presence or absence of defects is automatically inspected based on the captured image ( For example, see Patent Documents 1 and 2).

JP-A-4-276661 JP 2009-288089 A

  However, since visual inspection is performed by humans, there are variations in the accuracy of defect inspection, and there are problems such as overlooking minute defects. Further, in the conventional automatic inspection of defects, there is a problem that the inspection sensitivity of the defects is insufficient and the inspection takes time.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to improve the inspection sensitivity of a glass substrate for defects, and to reduce the time for inspecting defects, and a glass substrate defect inspection method and glass. It aims at providing the manufacturing method of the glass substrate which has the inspection process using the defect inspection apparatus of the board | substrate, and the said defect inspection method or the said defect inspection apparatus.

One form of the defect inspection method of the present glass substrate is to sequentially irradiate light from a plurality of directions onto a glass substrate having a first main plane and a second main plane which is the opposite surface, and sequentially capture images of the glass substrate. A sequential imaging step, and a defect inspection step for inspecting the glass substrate for defects on the first main plane and the second main plane based on images of the glass substrates sequentially imaged in the sequential imaging step, have a, the defect inspection process, dividing step and the color average value calculation step of calculating the color average value of the defect detection areas divided for dividing an image of each glass substrate said sequential imaging in a plurality of defect detection area In each defect detection area, a defect degree calculation step of calculating a defect degree that is a difference in color average value from all adjacent defect inspection areas, and a case where the calculated maximum value of the defect degree is equal to or greater than a determination value The defect detection area It is a requirement to include, recognizing defect recognizing step and a defect exists within.

Another form of the defect inspection method of the present glass substrate has a first main plane and a second main plane which is an opposing surface of the first main plane, and a circular hole penetrating from the first main plane to the second main plane is arranged at the center. An imaging step of irradiating the glass substrate having a light from either the first main plane or the second main plane and imaging the transmitted light from the glass substrate, and imaging in the imaging step based on the glass substrate of the transmitted light image, have a, a defect inspection step of inspecting the presence or absence of a defect of the inner peripheral end and outer peripheral end of the glass substrate, the defect inspection process, the transmitted light image of the glass substrate Dividing into a plurality of defect detection regions, a color average value calculating step of calculating a color average value of each defect detection region, and a color average value of all adjacent defect inspection regions in each defect detection region Defect degree calculation process for calculating the defect degree which is the difference, and calculation If the maximum value of the defective degree that is equal to or larger than the reference value, the defect recognizing step recognizes the defect defect detection area is present, to include a requirement.

The defect inspection apparatus for the glass substrate includes a first illuminating unit that sequentially irradiates light from a plurality of directions to a glass substrate having a first main plane and a second main plane that is a surface opposite thereto, and the first illuminating unit. An image pickup unit that sequentially picks up images of the glass substrate obtained by the light sequentially irradiated on the glass substrate, and the first main plane of the glass substrate based on images of the glass substrates picked up sequentially by the image pickup unit and wherein possess image processing means for inspecting the presence or absence of a defect of the second principal plane, wherein the image processing means divides the image of each glass substrate said sequential imaging in a plurality of defect detection area, the defect detection area When calculating the color average value, calculating the degree of defect that is the difference between the color average values of all the defect detection areas adjacent to each defect detection area, and the calculated maximum value of the defect degree is greater than or equal to the determination value In the defect detection area It is a requirement to recognize a defect exists.

  According to the present invention, the glass substrate defect inspection method and the glass substrate defect inspection apparatus capable of improving the defect inspection sensitivity and reducing the time for inspecting the defect than before, and the defect inspection method or The manufacturing method of the glass substrate which has an inspection process using the said defect inspection apparatus can be provided.

It is sectional drawing which illustrates a glass substrate. It is a schematic diagram which illustrates the defect inspection apparatus which concerns on 1st Embodiment. It is a top view for demonstrating the 2nd illumination means of the defect inspection apparatus of FIG. It is a top view for demonstrating the 1st illumination means of the defect inspection apparatus of FIG. It is a schematic diagram which illustrates a mode that light injects into a glass substrate from the diagonal direction. It is a flowchart which illustrates the defect inspection method which concerns on 1st Embodiment. FIG. 7A is a plan view for explaining image processing according to the first embodiment, FIG. 7A shows an area 51 and a defect detection area 52, and FIGS. 7B and 7C show a defect detection area. 5 is a diagram for explaining a pixel 52 and a pixel 53. FIG. It is a figure for demonstrating the difference in the image of the defect by an illumination direction. It is a flowchart which illustrates the manufacturing process of the glass substrate which concerns on 1st Embodiment. It is a top view for demonstrating the other example of the 1st illumination means of the defect inspection apparatus of FIG.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<First Embodiment>
[Glass substrate]
First, the glass substrate 90 to be subjected to defect inspection will be described. FIG. 1 is a cross-sectional view illustrating a glass substrate. The glass substrate 90 is a glass substrate for a magnetic recording medium (magnetic disk), and has a structure in which a circular hole 95 having a circular planar shape is formed at the center of the disk. The first main plane 91 and the second main plane 92 of the glass substrate 90 oppose each other, and the inner peripheral end 93 and the outer peripheral end 94 formed between the first main plane 91 and the second main plane 92 are Has been chamfered.

  In FIG. 1, since a glass substrate for a magnetic recording medium is illustrated as the glass substrate 90, it is depicted as having a circular hole in the center of the disk. The glass substrate is not limited to a glass substrate for a magnetic recording medium. That is, in the present embodiment, the glass substrate to be subjected to defect inspection is not limited to a disk shape, and may be a glass substrate having a rectangular planar shape, for example. However, in the following description, the case where the glass substrate 90 is a glass substrate for a magnetic recording medium will be described as an example.

[Glass substrate defect inspection system]
Next, the glass substrate defect inspection apparatus 10 will be described. FIG. 2 is a schematic view illustrating the defect inspection apparatus according to the first embodiment. FIG. 3 is a plan view for explaining the second illumination means of the defect inspection apparatus of FIG. FIG. 4 is a plan view for explaining the first illumination means of the defect inspection apparatus of FIG. FIG. 5 is a schematic view illustrating a state where light is incident on the glass substrate from an oblique direction. 2 to 5, one direction on the surface on which the mounting unit 60 to be described later mounts the glass substrate 90 is the X direction, the direction perpendicular thereto is the Y direction, and the mounting unit 60 mounts the glass substrate 90. The direction perpendicular to the surface to be aligned (the direction perpendicular to the X direction and the Y direction) is taken as the Z direction (the same applies to the following drawings).

  Referring to FIGS. 2 to 4, the defect inspection apparatus 10 generally includes a second illumination unit 20, a first illumination unit 30, an imaging unit 40, an image processing unit 50, and a placement unit 60. Have. Reference numeral 70 denotes input means, and 80 denotes output means.

  In the defect inspection apparatus 10, the second illumination means 20 has a function of illuminating the glass substrate 90 from below, and can illuminate an area sufficiently larger than the glass substrate 90 in plan view as shown in FIG. 3. It is said that. In the present embodiment, for convenience, the imaging means 40 side of the glass substrate 90 is referred to as the upper side, and the opposite side is referred to as the lower side.

  As the second illumination unit 20, for example, an LED array in which a plurality of white LEDs (Light Emitting Diodes) having intensities in almost the entire visible light region are arranged in parallel can be used. The number of LEDs constituting the second illuminating means 20 may be arbitrarily set, but it is arranged so densely that the entire area of the glass substrate 90 can be illuminated without omission, and the entire area of the glass substrate 90 can be illuminated uniformly. It is preferable to do. An optical component such as a diffusing plate or a deflecting plate may be disposed between the second illumination unit 20 and the glass substrate 90 as necessary. For example, the diffusing plate is disposed between the second illuminating unit 20 and the glass substrate 90 to enable uniform illumination, and the placing unit 60 when the first illuminating unit 30 is lit by disposing the deflecting plate. And reflection from the second illumination means 20 and the like can be reduced.

  The reason why the white LED is used is that when a color image is picked up by the image pickup means 40, if a specific color LED is used, that color becomes a noise component. For example, when a black and white image is picked up by the image pickup means 40, a specific color LED such as a blue LED can be used. However, the 2nd illumination means 20 is not limited to LED, It replaces with LED and uses fluorescent lamps, such as an organic EL element (Organic Electro-Luminescence element), a halogen lamp, a xenon lamp, a cold cathode tube, etc., for example. It doesn't matter. Each LED etc. which comprise the 2nd illumination means 20 irradiates the main plane of the glass substrate 90 from a substantially perpendicular direction.

  The 1st illumination means 30 has the function to illuminate the glass substrate 90 from an upper side, and as shown in FIG. 4, the illumination parts 31-34 are arrange | positioned so that the glass substrate 90 may be enclosed in planar view. As the illuminating units 31 to 34, as in the second illuminating unit 20, for example, an LED array in which a plurality of white LEDs having intensities in almost the entire visible light region are arranged in parallel can be used.

  The number of LEDs constituting the illuminating units 31 to 34 may be arbitrarily set, but is arranged so densely that the entire area of the glass substrate 90 can be illuminated without omission, and the entire area of the glass substrate 90 can be illuminated uniformly. It is preferable to do. You may arrange | position optical components, such as a diffusion plate, between the illumination parts 31-34 and the glass substrate 90 as needed. The illumination units 31 to 34 are not limited to LEDs, and instead of LEDs, for example, organic EL elements (Organic Electro-Luminescence elements), halogen lamps, xenon lamps, cold cathode fluorescent lamps, or the like are used. Also good.

  Each LED which comprises the illumination parts 31-34 irradiates the glass substrate 90 from the diagonal direction. In other words, as shown in FIG. 5, the light emitted from each LED constituting the illumination units 31 to 34 enters the glass substrate 90 on the XY plane from an oblique direction. Light incident on the glass substrate 90 from an oblique direction is repeatedly reflected in the glass substrate 90 and emitted from the glass substrate 90. Therefore, when there are no defects such as scratches or foreign objects on the first main plane 91 or the second main plane 92 of the glass substrate 90, light scattering due to defects such as scratches or foreign objects does not occur. On the other hand, when a defect such as a scratch or a foreign substance exists on the first main plane 91 or the second main plane 92 of the glass substrate 90, the incident light on the glass substrate 90 is scattered by the defect, and a part of the scattered light is scattered. Defects can be inspected because they go in the direction of the imaging means 40. However, it does not detect only the scattered light directed in the vertical direction (the direction of the imaging means 40). Even if the light is scattered by a defect such as a flaw or a foreign object and is directed in an oblique direction, there is a certain luminance. In this case, it can be captured by the imaging means 40. In addition, the illumination parts 31-34 light up sequentially, and do not light all the illumination parts simultaneously.

  The angle of light incident on the glass substrate 90 (angle formed with the XY plane) is preferably about 0 to 60 degrees. However, when the angle is set to 0 degrees (sometimes referred to as edge light), light enters the outer peripheral edge 94 of the glass substrate 90 substantially perpendicularly, and thus halation may occur. In particular, in the case of specular glass (transparent) with a small amount of attenuation of incident light compared to rubbed glass (opaque) with a large amount of attenuation of incident light, halation is likely to occur, so the angle of light incident on the glass substrate 90 is It is preferable to irradiate light from an oblique direction by selecting an appropriate incident angle within a range of more than 0 degree and 60 degrees or less.

  The imaging unit 40 includes a plurality of light receiving elements arranged in parallel in the X direction and the Y direction (for example, 5 million pixels), and acquires the amount of transmitted light of the light irradiated from the second illumination unit 20 onto the glass substrate 90. And has a function of capturing an image. In addition, the imaging unit 40 has a function of acquiring an amount of diffuse reflection light (scattered light at a defect) of light irradiated from the first illumination unit 30 to the glass substrate 90 and capturing an image. The imaging means 40 is arranged in a direction substantially perpendicular to the main plane of the glass substrate 90 (a position facing the second illumination means 20 through the glass substrate 90).

  As the imaging means 40, for example, a metal oxide semiconductor device (MOS), a complementary metal oxide semiconductor device (CMOS), a charge coupled device (CCD), a contact image sensor (CIS), or the like can be used. When a color image is targeted, an image sensor such as a 3-line type having sensitivity to each color of RGB may be used.

  By irradiating the glass substrate 90 with light from the vertical direction using the second illuminating means 20, and acquiring the amount of transmitted light of the light irradiated on the glass substrate 90 with the imaging means 40, an image is taken. Defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of 90 can be inspected. Note that chipping is a chipping of the glass substrate 90. Further, the light portions 31 to 34 of the first illuminating means 30 are used to sequentially irradiate the glass substrate 90 with light from an oblique direction, and the amount of diffusely reflected light (scattered light at the defect) of the light irradiated to the glass substrate 90. Can be inspected for defects in the first main plane 91 and the second main plane 92 of the glass substrate 90. At this time, since the defects of the first main plane 91 and the second main plane 92 of the glass substrate 90 can be inspected at a time without inverting the front and back of the glass substrate 90, the time for inspecting the defects can be shortened.

  The image processing unit 50 has a function of executing various arithmetic processes based on the image captured by the imaging unit 40 and inspecting defects. In addition to the function of inspecting defects, the image processing means 50 has a function of measuring the concentricity, roundness, inner diameter, outer diameter, etc. of the glass substrate 90 based on the image captured by the imaging means 40. You may have.

  The image processing unit 50 includes a CPU, a memory such as a ROM and a RAM (not shown), and the like. A program for inspecting defects is recorded in a memory (not shown) of the image processing unit 50, and various functions of the image processing unit 50 are realized by executing the program by a CPU (not shown). However, the program for inspecting the defect may be stored in a computer-readable recording medium such as an optical recording medium or a magnetic recording medium. The specific function of the image processing means 50 will be described in a glass substrate defect inspection method to be described later.

  The placement unit 60 is a member on which the glass substrate 90 is placed. Since the mounting unit 60 needs to transmit the light emitted from the second illumination unit 20, it is necessary to use a member that is transparent to the irradiation light of the second illumination unit 20. Further, it is preferable that the mounting portion 60 is made of a material that is flexible to some extent so as not to damage the glass substrate 90. As the mounting part 60, an acrylic board etc. can be used, for example. The glass substrate 90 only needs to be placed on the placement portion 60 and does not need to be particularly fixed. However, if the irradiation light from the second illumination means 20 or the first illumination means 30 is not adversely affected, a chucking for fixing the glass substrate 90 is provided on the mounting portion 60, and the glass substrate 90 is It may be fixed.

  The input means 70 is, for example, a start switch that instructs the defect inspection apparatus 10 to start defect inspection of the glass substrate 90, a stop switch that instructs the defect inspection apparatus 10 to end defect inspection of the glass substrate 90, and the like. This is the part where is provided. However, for example, when the placing portion 60 is provided on a tray configured to be reciprocally movable and the glass substrate 90 is placed on the placing portion 60 and the tray is pushed in, the tray is automatically inserted and stops at a predetermined position. A system in which the defect inspection is automatically started and the tray is automatically ejected when the defect inspection is completed may be employed. The output means 80 is, for example, a monitor that displays information on defects inspected by the defect inspection apparatus 10, a printer that prints information on defects inspected by the defect inspection apparatus 10, or blue if there is no defect (good product). If there is a defect (defective product), the display tube displays red.

  The surface of the glass substrate 90 to be inspected by the defect inspection apparatus 10 is in a frosted glass shape or a mirror surface state, but the defect inspection apparatus 10 is in any state regardless of the surface roughness of the glass substrate 90. Even inspection is possible. The thickness of the glass substrate 90 that can be inspected by the defect inspection apparatus 10 is about 10 mm or less. However, if the brightness of the second illumination means 20 and the first illumination means 30 can be sufficiently secured, it is possible to detect a defect in a glass substrate having a thickness of 10 mm or more.

[Glass substrate defect inspection method]
Next, a method for performing a defect inspection of the glass substrate 90 using the defect inspection apparatus 10 will be described. FIG. 6 is a flowchart illustrating the defect inspection method according to the first embodiment. First, in step S100, the glass substrate 90 is placed on the placement unit 60, and the start switch of the input means 70 is pressed. As described above, the placement unit 60 is provided on a tray configured to be able to reciprocate, and when the glass substrate 90 is placed on the placement unit 60 and the tray is pushed in, the defect inspection is automatically started. It doesn't matter if you do.

  When the start switch of the input means 70 is pressed, first, in steps S110 to S140, defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94, which are one of the defects of the glass substrate 90, are inspected. Specifically, in step S <b> 110, the second illumination unit 20 is turned on, the glass substrate 90 is irradiated with light from below, and the transmitted light from the glass substrate 90 is imaged by the imaging unit 40. Then, the second illumination means 20 is turned off.

  In step S120, the image processing means 50 processes the image captured in step S110. Specifically, the image processing unit 50 divides the image of the glass substrate 90 captured in step S110 into a plurality of defect detection areas, calculates a color average value of each defect detection area, and in each defect detection area, A defect degree that is a difference in color average value from all defect inspection areas to be calculated is calculated. Then, based on the calculated defect degree, the defect detection area where the defect exists is recognized. In this case, since defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90 are inspected, the vicinity of the inner peripheral end 93 and the outer peripheral end 94 is divided into a plurality of defect detection areas, and defects exist. The defect detection area to be recognized is recognized.

  As an example of processing, as shown in FIG. 7A, the image processing means 50 selects a region 51 including, for example, nine defect detection regions 52. As shown in FIG. 7B, each defect detection area 52 includes, for example, nine pixels 53 (each pixel 53 is a minimum unit of an image). When the resolution of the imaging means 40 is 5 million pixels, one pixel (each pixel 53) corresponds to about 40 μm. The region 51 may include a number of defect detection regions 52 other than nine, and each defect detection region 52 may include a number of pixels 53 other than nine.

  Next, the image processing means 50 calculates the color average value of each of the nine defect detection areas 52 included in the area 51, and calculates the center defect detection area 52 and the eight defect detection areas 52 adjacent thereto. Defect degrees, which are differences in color average values, are calculated. If the maximum value of the calculated eight defect degrees is equal to or greater than a predetermined determination value, it is recognized that a defect exists in the defect detection area 52.

When the imaging means 40 is a color camera, a value obtained by averaging luminance (RGB) is a color average value, and a difference in color average value between a predetermined defect detection area 52 and a defect detection area 52 adjacent thereto. Can be expressed as a color difference. This color difference becomes the degree of defect. For example, the value (r1, g1, b1) when the luminance (RGB) of the predetermined defect detection area 52 is recognized with 256 gradations of RGB is assumed. Similarly, the value (r2, g2, b2) when the luminance (RGB) of one defect detection area 52 adjacent to the defect detection area 52 is similarly recognized with 256 gradations of RGB. At this time, color difference = √ (r1−r2) ² + (g1−g2) ² + (b1−b2) ² , and the color difference (= defect degree) can be expressed as a distance in a three-dimensional space.

  In this way, the color difference (= defect degree) between the defect detection area 52 in the center of the area 51 and the eight defect detection areas 52 adjacent thereto is expressed as a distance in the three-dimensional space, and the maximum value is a predetermined value. If it is equal to or greater than the determination value, it is recognized that a defect exists in the defect detection area 52. Next, as shown in FIG. 7C, the region 51 is shifted by one pixel and the same processing is repeated (in the example of FIG. 7C, the region 51 is shifted to the right by one pixel). Such processing is performed for all the defect detection areas 52 in the vicinity of the inner peripheral edge 93 and the outer peripheral edge 94, and a predetermined determination result flag indicating the defect detection area 52 recognized as having a defect is set.

  When the imaging unit 40 is a black and white camera, the average gray value obtained by averaging the gray levels is the color average value, and the color average value of the predetermined defect detection area 52 and the defect detection area 52 adjacent thereto is obtained. The difference can be expressed as a shading difference. This density difference is the defect degree. For example, let A be the average gray value of the defect detection area 52 in the center of the area 51. Further, the average density values of the eight defect detection areas 52 adjacent to the defect detection areas 52 are set to B, C, D, E, F, G, H, and I, respectively. In this case, if the maximum value of the contrast between A and B to I is equal to or greater than a predetermined determination value, it is recognized that a defect exists in the defect detection area 52. Other processes are the same as when the imaging means 40 is a color camera.

  In this way, the captured image is divided into a large number of defect detection areas, the color average value of each divided defect detection area is calculated, and the difference in color average value between all adjacent defect inspection areas for each defect detection area is calculated. A certain defect degree is calculated. When the calculated maximum value of the defect degree is equal to or greater than a predetermined determination value, it is recognized that a defect exists in the defect detection area. As a result, even if the color of the entire image is uneven, it is possible to detect defects with high accuracy.

  Returning to FIG. 6, in step S <b> 130, the image processing unit 50 stores the data inspected in step S <b> 120 including the determination result flag in a memory (not shown) of the image processing unit 50. Other than the determination result flag, for example, the coordinates where the defect exists and the degree of defect can be stored in the memory.

  In step S140, the image processing unit 50 outputs the determination result in step S120 to the output unit 80 (for example, displays it on a monitor). The defect inspection such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90 is thus completed.

  In addition to the defect inspection such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90 in Steps S110 to S140, the image processing unit 50 concentrics the glass substrate 90 based on the image captured by the imaging unit 40. Measure the degree, roundness, inner diameter, outer diameter, etc.

  Next, in steps S150 to S230, the first main plane 91 and the second main plane 92 of the glass substrate 90 are inspected for defects. Specifically, in step S150, the illumination units 31 to 34 of the first illumination unit 30 are sequentially turned on to obliquely irradiate the glass substrate 90 with light from a plurality of upper directions, and an image such as scattered light from the glass substrate 90. Are sequentially imaged by the imaging means 40. And the illumination parts 31-34 of the 1st illumination means 30 are light-extinguished sequentially. That is, the illumination unit 31 of the first illumination unit 30 is turned on, light is obliquely irradiated onto the glass substrate 90 from above, and an image such as scattered light from the glass substrate 90 is captured by the imaging unit 40. Then, the illumination unit 31 is turned off, the illumination unit 32 is turned on, and the glass substrate 90 is obliquely irradiated with light from another upper side, and an image such as scattered light from the glass substrate 90 is captured by the imaging unit 40. Similarly, the lighting units 33 and 34 are sequentially turned on, imaged, and turned off. Thereby, four images captured by sequentially irradiating light from four different directions are obtained.

  Prior to step S150, the angle of light incident on the glass substrate 90 from the illumination units 31 to 34 (XY plane) in accordance with the state of the glass substrate 90 that is the inspection object (the rubbed glass state or the mirror surface state). Angle), the intensity of the emitted light from the illumination units 31 to 34, the angle of the emitted light from the illumination units 31 to 34, the distance from the illumination units 31 to 34 to the glass substrate 90, and must be adjusted to appropriate values in advance. There is. As a result, the occurrence of halation is prevented.

  In step S160, the image processing unit 50 processes each image (four images) captured in step S150. Similar to step S120, the image processing unit 50 divides each image (four sheets) into a large number of defect detection areas and recognizes defects. However, unlike step S120, not only the inner peripheral edge 93 and the outer peripheral edge 94 of the glass substrate 90 but also the entire area of the glass substrate 90 is divided into defect detection areas to recognize defects. Then, a predetermined determination result flag indicating a defect detection area recognized as having a defect is set.

  In step S170, the image processing unit 50 stores the data inspected in step S160 including the determination result flag in a memory (not shown) of the image processing unit 50, as in step S130. In step S180, as in step S140, the image processing unit 50 outputs the determination result in step S160 to the output unit 80 (for example, displays on the monitor).

  The defect inspection for each image obtained by obliquely irradiating the glass substrate 90 from a plurality of directions on the upper side is completed as described above. In this embodiment, each image (four images) captured in step S150 is further synthesized. The defect inspection is also performed on the synthesized image. In addition, the defect inspection of the glass substrate 90 is possible only by steps S150 to S180. However, furthermore, by synthesizing each image (four images) captured in step S150, and performing defect inspection on the synthesized image, a defect area that does not appear insensitive area and is difficult to be confirmed only by irradiation from one direction. It can be detected accurately. That is, the defect detection sensitivity can be improved.

  In step S190, the image processing means 50 synthesizes each image (four images) captured in step S150 to generate one synthesized image. In step S200, the image processing means 50 processes the synthesized image (one sheet) synthesized in step S190. Similar to step S160, the image processing unit 50 divides the composite image (one sheet) into a large number of defect detection areas to recognize defects. In step S210, the image processing unit 50 outputs the determination result in step S200 to the output unit 80 (for example, displays it on a monitor) in the same manner as in step S180.

  In step S220, the image processing means 50 performs comprehensive determination. The condition for comprehensive determination may be determined as appropriate, but here, when a defect is recognized in any of the determination result in step S120, the determination result in step S160, and the determination result in step S200, the comprehensive determination is made. Is defective (defective).

  In step S230, the image processing unit 50 outputs the comprehensive determination result to the output unit 80 (for example, displays “no defect (good product)” or “has a defect (defective product)” on the monitor). In step S240, the stop switch of the input means 70 is pressed to reset the measurement, and the glass substrate 90 is taken out from the placement unit 60. As described above, the tray may be automatically ejected when the defect inspection is completed, and at the same time, the measurement may be reset.

  Note that if the comprehensive determination is defective (defective product) in step S220, data logging, remeasurement, or the like may be performed. An example is given below. If it is determined in step S220 that the overall determination is defective (defective product), the image processing unit 50 outputs the fact to the output unit 80 (for example, displays “defective (defective product)” on the monitor). The measurement data is output and stored in an external storage device having a magnetic recording medium or an optical recording medium (data logging).

  When performing re-measurement, specify the location to be re-measured. For example, the illumination unit corresponding to the location to be remeasured in the illumination units 31 to 34 of the first illumination unit 30 is turned on, and light is obliquely irradiated on the glass substrate 90 from above, and the scattered light from the glass substrate 90 is imaged. The image is taken by means 40. Then, the illuminated illumination unit is turned off. Then, the image processing means 50 recognizes the defect by dividing the image taken for remeasurement into a large number of defect detection areas in the same manner as in step S160, and outputs the determination result in the same manner as in step S180. Output to 80 (for example, displayed on a monitor). In addition, you may remeasure with the 2nd illumination means 20, or you may remeasure with the synthesized image which irradiated the illumination parts 31-34 of the 1st illumination means 30 sequentially.

  Thus, all defect inspections for the glass substrate 90 are completed. When there is a concern about the influence of external light, it is preferable to inspect the glass substrate 90 for defects by placing the defect inspection apparatus 10 in a box or the like capable of shielding external light.

  Here, the illumination units 31 to 34 of the first illumination unit 30 are arranged so as to surround the glass substrate 90 in plan view, the illumination units 31 to 34 are sequentially turned on to acquire images, and the acquired images are synthesized. The effect to do is demonstrated. FIG. 8 is a diagram for explaining the difference in the defect image depending on the illumination direction. FIG. 8A schematically shows an image of the defect 100a acquired by lighting only the illumination unit 31. FIG. FIG. 8B schematically shows an image of the defect 100b acquired by lighting only the illumination unit 33. FIG. FIG. 8C schematically shows an image of the defect 100c obtained by synthesizing the image of the defect 100a in FIG. 8A and the image of the defect 100b in FIG.

  As shown in FIG. 8A, when only the illumination unit 31 is turned on and the glass substrate 90 is obliquely irradiated with light, only the side opposite to the defective illumination unit 31 (the lower side of the paper surface) shines. Such an image is acquired. That is, a clear image on the defective illumination unit 31 side (the broken line portion above the defective paper surface) cannot be acquired. Further, as shown in FIG. 8B, when only the illumination unit 33 is turned on and the glass substrate 90 is obliquely irradiated with light, only the side opposite to the defect illumination unit 33 (upper side in the drawing) is illuminated, so that the defect 100b An image like this is acquired. In other words, a clear image on the defective illumination unit 33 side (the broken line portion on the lower side of the defective paper surface) cannot be acquired.

  Therefore, as shown in FIG. 8C, the image of the defect 100a in FIG. 8A and the image of the defect 100b in FIG. An image of the defect 100c in which both sides are bright and clear is obtained, the defect is more easily detected, and the defect detection sensitivity is improved.

  In this way, it is difficult to confirm by only irradiating from one direction by providing illumination units arranged opposite to each other like the illumination unit 31 and the illumination unit 33 and combining the images acquired by sequentially lighting them. A defect image can be obtained with high accuracy. In other words, it is possible to reliably detect a defect that cannot be detected only by irradiation from one direction but flows out.

  Here, the illumination unit 31 and the illumination unit 33 have been described as examples. However, since the illumination unit 32 and the illumination unit 34 are also illumination units arranged to face each other, the same effect can be obtained. Furthermore, since the illumination parts 31-34 are arrange | positioned so that the glass substrate 90 may be enclosed in planar view, by illuminating the illumination parts 31-34 sequentially, an image is acquired, and the acquired image is combined, Accurate defect detection is possible without generating a dead area.

[Glass substrate manufacturing method]
Next, a method for manufacturing the glass substrate 90 will be described. FIG. 9 is a flowchart illustrating the manufacturing process of the glass substrate according to the first embodiment. First, in the shape imparting step 400, for example, an original glass substrate having a shape corresponding to FIG. 1 is processed by processing a base glass formed by a float method, a fusion method, a press molding method, or the like (hereinafter, for convenience, the original glass substrate). 99). The original glass substrate 99 is a substrate that eventually becomes the glass substrate 90. Specifically, for example, a circular hole is formed in the base glass and the disk-shaped original glass substrate 99 is cut out so that the circular hole is located at the center. Then, chamfering is performed on the inner peripheral end and the outer peripheral end of the original glass substrate 99.

  Next, in the end surface polishing step 410, for example, the inner peripheral end and the outer peripheral end including the chamfered portion are polished using a polishing liquid containing abrasive grains, a polishing brush, a polishing pad, and the like to obtain a mirror surface.

  Next, in the lapping step 420, the first main plane and the second main plane of the original glass substrate 99 are lapped. By wrapping the first main plane and the second main plane of the original substrate 99, the flatness and thickness of the original glass substrate are made uniform. The lapping step 420 may be performed before the end surface polishing step 410 or may be performed both before and after the end surface polishing step 410.

  Next, in the polishing step 430, for example, the first main plane and the second main plane of the original glass substrate 99 are polished using a polishing liquid containing abrasive grains and a polishing pad. In the polishing step 430, only primary polishing may be performed, primary polishing and secondary polishing may be performed, or tertiary polishing may be performed after secondary polishing.

  In the polishing step 430, the first main plane and the second main plane of the original glass substrate 99 are, for example, a polishing liquid containing an abrasive pad made of hard urethane and cerium oxide abrasive as an abrasive (average particle diameter, hereinafter referred to as average particle). The primary polishing can be performed by a double-side polishing apparatus using a polishing liquid composition having a diameter of about 1.3 μm as a main component. In the primary polishing process, the polishing pads mounted on the upper and lower surface plates of the double-side polishing apparatus are dressed using a dressing jig made of pellets containing diamond abrasive grains before the original glass substrate 99 is polished. Is formed on a predetermined polished surface.

  When secondary polishing is performed after primary polishing, the first main plane and the second main plane of the original glass substrate 99 after the primary polishing are, for example, a polishing pad made of soft urethane as a polishing tool, Using a polishing liquid (such as a polishing liquid composition mainly composed of cerium oxide having an average particle diameter of about 0.5 μm) containing cerium oxide abrasive grains having an average particle diameter smaller than that of the cerium oxide abrasive grains used in the polishing step. Secondary polishing can be performed by a double-side polishing apparatus. After the secondary polishing, the cerium oxide is washed away.

  When performing tertiary polishing after secondary polishing, the first main plane and the second main plane of the original glass substrate 99 after the secondary polishing are, for example, a polishing pad made of soft urethane as a polishing tool, and colloidal silica. Can be subjected to tertiary polishing by a double-side polishing apparatus using a polishing liquid containing a polishing liquid (such as a polishing liquid composition mainly composed of colloidal silica having an average primary particle diameter of 20 to 30 nm).

  Next, in the cleaning step 440, the original glass substrate 99 whose inner peripheral end and outer peripheral end, and the first main plane and the second main plane are mirror-polished is precisely cleaned and dried. The original glass substrate 99 is sequentially subjected to, for example, scrub cleaning with an alkaline detergent, ultrasonic cleaning in a state immersed in an alkaline detergent solution, and ultrasonic cleaning in a state immersed in pure water, and dried with isopropyl alcohol vapor. be able to. Thus, the glass substrate 90 shown in FIG. 1 is completed.

In addition, between each process of the manufacturing process of the said glass substrate 90, you may implement the cleaning (interprocess cleaning) of the original glass substrate 99 and the etching (interprocess etching) of the surface of the original glass substrate 99. Further, when high mechanical strength is required for the original glass substrate 99, a strengthening step (for example, a chemical strengthening step) for forming a reinforcing layer on the surface layer of the original glass substrate 99 is performed before the polishing step, after the polishing step, or the polishing step. You may carry out between. The original glass substrate 99 may be amorphous glass, crystallized glass, or tempered glass (for example, chemically tempered glass) having a tempered layer on the surface layer.

By the way, in the manufacturing process of the glass substrate 90, it is preferable to perform a defect inspection of the original glass substrate 99 using the defect inspection apparatus 10 described above. For example, by performing a defect inspection after the cleaning process 440, it is possible to prevent the glass substrate 90 having defects on the inner peripheral end and the outer peripheral end, and the first main plane and the second main plane from being shipped as a final product. .

  Further, by performing defect inspection between the shape imparting step 400 and the end surface polishing step 410 or between the lapping step 420 and the polishing step 430, defects such as chipping are found at the inner peripheral end and the outer peripheral end. It is possible to prevent the formed original substrate 99 and the original glass substrate 99 in which defects such as scratches are formed on the first main plane and the second main plane from flowing out to the subsequent process. As a result, since the defective original glass substrate 99 does not flow out to the subsequent process, for example, it is possible to prevent the original substrate 99 being polished from being damaged due to the presence of the defect and stop the polishing apparatus. The operating rate of the polishing apparatus can be improved by shortening the stop time. In addition, it is possible to prevent the original glass substrate 99 having scratches or defects such as chipping beyond the depth that cannot be removed by polishing in the subsequent process from flowing out to the subsequent process.

  As described above, according to the first embodiment, the second illumination unit 20 that can illuminate a region sufficiently wider than the glass substrate 90 is used to irradiate the main plane of the glass substrate 90 from a substantially vertical direction. The light transmitted through the glass substrate 90 is imaged by the imaging means 40. Then, predetermined image processing is performed on the image picked up by the image pickup means 40. As a result, defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90 can be inspected.

  Further, when inspecting defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90, the concentricity, roundness, inner diameter, outer diameter, etc. of the glass substrate 90 can be simultaneously measured.

  Further, the illumination units 31 to 34 of the first illumination means 30 are arranged so as to surround the glass substrate 90 in plan view, and light is sequentially irradiated on the glass substrate 90 from a plurality of upper directions. The diffused scattered light is sequentially imaged by the imaging means 40. Then, a predetermined image processing is performed on each sequentially captured image to perform defect inspection. As a result, it is possible to detect all the direction-dependent defects, and it is possible to accurately detect defects that are difficult to be confirmed only by irradiation from one direction without generating a dead area.

  Further, since the defects of the first main plane 91 and the second main plane 92 of the glass substrate 90 can be inspected at a time without inverting the front and back of the glass substrate 90, the defect inspection time can be shortened.

  Further, a single composite image is generated by combining the images sequentially picked up by the image pickup means 40, and a predetermined image processing is performed on the composite image to perform defect inspection. As a result, it is possible to accurately detect a defect that is difficult to confirm only by irradiation from one direction without generating a dead area. Furthermore, the defect detection sensitivity can be improved by using the composite image.

  Also, in image processing, the captured or synthesized image is divided into a large number of defect detection areas, the color average value of each divided defect detection area is calculated, and the color average of all defect detection areas with the adjacent all defect inspection areas The defect degree which is a difference in values is calculated. When the calculated maximum value of the defect degree is equal to or greater than a predetermined determination value, it is recognized that a defect exists in the defect detection area. As a result, even if the color of the entire image is uneven, it is possible to detect defects with high accuracy.

  Moreover, the glass which has a defect in the inner peripheral end 93 and the outer peripheral end 94, the 1st main plane 91, and the 2nd main plane 92 by performing the defect inspection method which concerns on 1st Embodiment in the manufacturing process of a glass substrate. It is possible to prevent the substrate 90 from being shipped as a final product.

  According to the examination by the inventors, when 8600 substrates determined to be normal by visual inspection were re-inspected by the defect inspection apparatus 10, 14 substrates having defects (defective substrates) were detected. The time for inspecting one glass substrate 90 by the defect inspection apparatus 10 was 3 seconds. As described above, it was confirmed that the defect inspection apparatus 10 can perform an accurate defect inspection in a short inspection time.

<Variation 1 of the first embodiment>
In the first modification of the first embodiment, an example in which the first illumination unit 35 is used instead of the first illumination unit 30 of the first embodiment is shown. In the first modification of the first embodiment, the description of the same parts as those already described in the first embodiment will be omitted.

  FIG. 10 is a plan view for explaining another example of the first illumination means of the defect inspection apparatus of FIG. 10 has the function of illuminating the glass substrate 90 from above, as in the first illumination unit 30 of the first embodiment, and a plurality of light emitting elements are made of glass in plan view. It arrange | positions so that the board | substrate 90 may be enclosed concentrically. As the light emitting element constituting the first illumination unit 35, for example, a white LED having an intensity in almost the entire visible light region can be used as in the first illumination unit 30.

  The number of light-emitting elements constituting the first illumination means 35 may be arbitrarily set, but it is arranged so densely that the entire glass substrate 90 can be illuminated without omission, and the entire glass substrate 90 can be illuminated uniformly. It is preferable to do. An optical component such as a diffusing plate may be disposed between the light emitting element constituting the first illumination unit 35 and the glass substrate 90 as necessary. The light emitting element constituting the first illuminating means 35 is not limited to the LED, and instead of the LED, for example, fluorescent light such as an organic EL element (Organic Electro-Luminescence element), a halogen lamp, a xenon lamp, a cold cathode tube or the like. A lamp or the like may be used.

Since each light emitting element constituting the first illumination unit 35 irradiates the glass substrate 90 from an oblique direction, the first main plane 91 and the second main plane 92 of the glass substrate 90 are scratched similarly to the first illumination unit 30. When there is no defect such as a foreign substance or the like, scattered light due to the defect is not incident on the imaging means 40. On the other hand, when a defect such as a scratch or a foreign object exists on the first main plane 91 and the second main plane 92 of the glass substrate 90, the incident light on the glass substrate 90 is irregularly reflected by the defect and a part of the scattered light is generated. Since it goes in the direction of the imaging means 40, it is possible to inspect the defect. However, it does not detect only the scattered light directed in the vertical direction (the direction of the imaging means 40). Even if the light is scattered by a defect such as a flaw or a foreign object and is directed in an oblique direction, there is a certain luminance. In this case, it can be captured by the imaging means 40. Note that the angle of light incident on the glass substrate 90 (the angle formed with the XY plane) is the same as that of the first illumination unit 30. When the defect inspection is performed using the first illumination unit 35, the first illumination is performed. It is necessary to sequentially turn on each light emitting element constituting the means 35 to acquire an image. However, it is not always necessary to turn on each of the light emitting elements constituting the first illumination unit 35. It is only necessary to consider several adjacent light emitting elements as light emitting element pairs and sequentially turn on the light emitting element pairs (same as above). The light emitting elements belonging to the light emitting element pair are turned on simultaneously).

  Thus, according to the first modification of the first embodiment, a plurality of light emitting elements are arranged so as to surround the glass substrate 90 concentrically instead of the first illumination means 30 of the first embodiment. Even if the 1st illumination means 35 currently used is used, there exists an effect similar to 1st Embodiment.

<Modification 2 of the first embodiment>
Modification 2 of the first embodiment shows an example in which the influence of the abrasive (slurry) adhering to the glass substrate is removed to further improve the accuracy of defect detection. In the second modification of the first embodiment, the description of the same parts as those already described in the first embodiment is omitted.

  There is a case where a ground or polished glass substrate is inspected between processes in each process of manufacturing a glass substrate. When performing an inter-process inspection, an abrasive (slurry) may adhere to the first main plane 91 or the second main plane 92 of the glass substrate 90 to be inspected. If an abrasive (slurry) is attached to the first main plane 91 or the second main plane 92 of the glass substrate 90, the abrasive (slurry) may be erroneously detected as a defect such as a scratch. It is preferable to remove the influence of the slurry. A method for removing the influence of the abrasive (slurry) will be described below.

  First, in steps S110 to S140 in FIG. 6, when inspecting defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90, the presence or absence of an abrasive (slurry) is simultaneously inspected. Since the abrasive (slurry) uses a material of a specific color, by comparing the image captured in color with the color information of the abrasive (slurry) stored in the memory of the image processing unit 50 in advance, The presence or absence of an abrasive (slurry) can be inspected. At this time, since defects such as scratches do not have a specific color, the abrasive (slurry) can be distinguished from defects such as scratches.

  Next, when recognizing a defect in step S160 or the like, it is possible to prevent the abrasive (slurry) from being erroneously detected as a defect by excluding the coordinates to which the abrasive (slurry) is attached from the defect inspection. In step S160 and the like, defect inspection is performed using an image captured in color. However, since the glass substrate 90 is irradiated with light from an oblique direction, the detection accuracy of the color information of the abrasive (slurry) is low. Therefore, the inspection for the presence of the abrasive (slurry) is preferably performed in steps S <b> 110 to S <b> 140 in which light is irradiated from the direction perpendicular to the main plane of the glass substrate 90.

  As described above, according to the second modification of the first embodiment, the same effects as those of the first embodiment are obtained, but the following effects are further obtained. That is, when the second illumination unit 20 illuminates light from the lower side of the glass substrate 90 and inspects defects such as chipping of the inner peripheral end 93 and the outer peripheral end 94, the presence or absence of abrasive (slurry) is simultaneously inspected. . Then, when the first illumination unit 30 irradiates the glass substrate 90 with light from an oblique direction, the coordinates to which the abrasive (slurry) is attached are excluded from the defect inspection. Thereby, the influence of the abrasive (slurry) adhering to the glass substrate 90 can be removed, and the accuracy of defect detection of the glass substrate 90 can be further improved.

  The preferred embodiment and its modification have been described in detail above, but the present invention is not limited to the above-described embodiment and its modification, and the above-described implementation is performed without departing from the scope described in the claims. Various modifications and substitutions can be added to the embodiment and its modifications.

  For example, it is possible to realize an apparatus that does not have the first illuminating unit 30 and images only the transmitted light from the second illuminating unit 20 with the imaging unit 40 and performs image processing with the image processing unit 50 to inspect the defect. In the above-described embodiment, the example in which the defect inspection of the inner peripheral end 93 and the outer peripheral end 94 of the glass substrate 90 is performed using the transmitted light from the second illumination unit 20 is described. It is also possible to perform defect inspection such as scratches on the first main plane 91 and the second main plane 92 of the glass substrate 90. However, the transmitted light from the second illuminating means 20 is also transmitted through the mounting portion 60, so that there is a risk of detecting a scratch on the mounting portion 60. From this point of view, when the defect inspection is required for the first main plane 91 and the second main plane 92 of the glass substrate 90 with higher accuracy, the second illumination unit 20 and the first illumination such as the defect inspection apparatus 10 are used. It is preferable to use a defect inspection apparatus having means 30. In addition, since the 1st illumination means 30 irradiates the glass substrate 90 from the diagonal direction, the possibility of misdetecting the damage of the mounting part 60 is very low.

  Further, the second illumination means may be arranged so as to surround the glass substrate 90 in a regular hexagonal shape or a regular octagonal shape in plan view.

  Further, when the presence or absence of an abrasive (slurry) using a material of a specific color is not detected, it is not necessary to acquire color information. Therefore, a blue light source is used as the second illumination unit 20 and the first illumination unit 30 to perform imaging. A black and white camera can be used as the means 40. Note that a light source of another color such as red may be used instead of the blue light source.

DESCRIPTION OF SYMBOLS 10 Defect inspection apparatus 20 2nd illumination means 30, 35 1st illumination means 31, 32, 33, 34 Illumination part 40 Imaging means 50 Image processing means 50A, 50B Defect detection area 60 Mounting part 70 Input means 80 Output means 90 Glass Substrate 90A Image 91 First main plane 92 Second main plane 93 Inner edge 94 Outer edge 95 Circular hole 100a, 100b, 100c Defect

Claims (20)

A sequential imaging step of sequentially irradiating light from a plurality of directions and sequentially capturing images of the glass substrate to the glass substrate having the first main plane and the second main plane that is the opposite surface;
On the basis of the image of each glass substrate are sequentially captured in a sequential imaging step, have a, a defect inspection step of inspecting the presence or absence of a defect of the first principal plane and the second principal plane of the glass substrate,
The defect inspection step is a division step of dividing the sequentially imaged glass substrate images into a plurality of defect detection regions;
A color average value calculating step for calculating a color average value of each of the divided defect detection areas;
In each of the defect detection areas, a defect degree calculating step of calculating a defect degree that is a difference in color average value from all adjacent defect inspection areas;
And a defect recognition step for recognizing that a defect exists in the defect detection area when the calculated maximum value of the defect degree is equal to or greater than a determination value . Further comprising an image synthesis step of generating a synthesized image by synthesizing images of the glass substrates taken sequentially in the sequential imaging step;
The said defect inspection process inspects the presence or absence of the defect of the said 1st main plane and the said 2nd main plane of the said glass substrate based on the said image and each synthesized image of each glass substrate which were sequentially imaged. Defect inspection method for glass substrates.   The sequential imaging step sequentially irradiates light from a plurality of directions from one main plane side of the first main plane or the second main plane so that light is transmitted through the glass substrate. The glass substrate defect inspection method according to 1 or 2.   The glass substrate defect inspection method according to claim 1, wherein at least a pair of the plurality of directions are opposed to each other with the glass substrate in a plan view. The glass substrate has a circular hole penetrating from the first main plane to the second main plane in a central portion,
The inspection method is:
An imaging step of irradiating light from either one of the first main plane or the second main plane and imaging the transmitted light from the glass substrate;
5. The second defect inspection step of inspecting the presence or absence of defects at the inner peripheral end and the outer peripheral end of the glass substrate based on the transmitted light image of the glass substrate imaged in the imaging step. The defect inspection method of the glass substrate as described in any one of Claims. In the second defect inspection step, based on the transmitted light image of the glass substrate imaged in the imaging step, the presence or absence of defects at the inner peripheral end and the outer peripheral end of the glass substrate, and the first main plane or Inspecting the presence or absence of the abrasive adhered to the second main plane,
When inspecting the presence or absence of defects on the first main plane and the second main plane of the glass substrate in the defect inspection step, based on the inspection result in the second defect inspection step, The glass substrate defect inspection method according to claim 5, wherein attached coordinates are excluded from inspection. The glass substrate has a disk shape with a circular hole in the center,
The defect inspection process based on the transmitted light image of the glass substrate obtained by imaging, concentricity of the glass substrate, roundness, inside diameter, according to claim 5 or 6, wherein measuring at least one of outer diameter Defect inspection method for glass substrates. The division step, the you divide the transmitted light image of the composite image or the glass substrate instead of the glass substrates of images sequentially captured in a plurality of defect detection area 請 Motomeko 2,5,6, or 7 The defect inspection method of the glass substrate of description. A glass substrate having a first main plane and a second main plane opposite to the first main plane and having a circular hole penetrating from the first main plane to the second main plane in a central portion thereof, the first main plane or the An imaging step of irradiating light from any one of the second principal planes and imaging the transmitted light from the glass substrate;
Based on the transmitted light image of the glass substrate taken by the image pickup step, have a, a defect inspection step of inspecting the presence or absence of a defect of the inner peripheral end and outer peripheral end of the glass substrate,
The defect inspection step is a division step of dividing the transmitted light image of the glass substrate into a plurality of defect detection regions;
A color average value calculating step of calculating a color average value of each defect detection area;
In each of the defect detection areas, a defect degree calculating step of calculating a defect degree that is a difference in color average value from all adjacent defect inspection areas;
And a defect recognition step for recognizing that a defect exists in the defect detection area when the calculated maximum value of the defect degree is equal to or greater than a determination value . The glass substrate has a disk shape with a circular hole in the center,
10. The glass substrate according to claim 9, wherein in the defect inspection step, at least one of concentricity, roundness, inner diameter, and outer diameter of the glass substrate is measured based on a captured light image of the glass substrate. Defect inspection method. A first illuminating means for sequentially irradiating light from a plurality of directions to a glass substrate having a first main plane and a second main plane that is the opposite surface, and light that is sequentially emitted from the first illuminating means to the glass substrate. Imaging means for sequentially capturing images of the glass substrate obtained by
Based on the image of each glass substrate on which the imaging means sequentially captured, we have a, and an image processing means for inspecting the presence or absence of a defect of the first principal plane and the second principal plane of the glass substrate,
The image processing means divides the sequentially imaged glass substrate images into a plurality of defect detection areas, calculates a color average value of each defect detection area, and all defect inspection areas adjacent to each defect detection area; of calculating the defectivity is the difference between the average color value, calculated defect inspection apparatus for a glass substrate to recognize a defect exists in the defect detection area when the maximum value of the defective degree is equal to or larger than the reference value.   The image processing unit generates a composite image by combining images of the glass substrates sequentially captured by the imaging unit, and based on the sequentially captured images of the glass substrates and the composite image, the glass substrate The glass substrate defect inspection apparatus according to claim 11, wherein the presence or absence of defects on the first main plane and the second main plane is inspected. The first illumination means includes a plurality of illumination units,
The defect inspection apparatus for a glass substrate according to claim 11 or 12, wherein at least a part of the illumination unit is disposed so as to face the glass substrate in plan view. The glass substrate has a circular hole penetrating from the first main plane to the second main plane in a central portion,
The defect inspection apparatus includes:
A second illumination means for irradiating light from either one of the first main plane and the second main plane;
The imaging means images the transmitted light of the light irradiated on the glass substrate from the second illumination means,
The said image processing means test | inspects the presence or absence of the defect of the inner peripheral end of the said glass substrate and an outer peripheral end based on the transmitted light image of the said glass substrate imaged by the said imaging means. The glass substrate defect inspection apparatus described. The image processing means inspects for the presence or absence of defects at the inner peripheral edge and the outer peripheral edge of the glass substrate based on the transmitted light image of the glass substrate imaged by the imaging means, and the first main plane or the second Inspect for abrasive material adhering to the main plane,
  When inspecting the glass substrate for the presence or absence of defects on the first main plane and the second main plane, based on the inspection result of the presence or absence of the abrasive, the coordinates of the abrasive are attached. The glass substrate defect inspection apparatus according to claim 14 to be excluded. The glass substrate has a disk shape with a circular hole in the center,
The glass according to claim 14 or 15 , wherein the image processing means measures at least one of concentricity, roundness, inner diameter, and outer diameter of the glass substrate based on a transmitted light image of the glass substrate. Substrate inspection system. Wherein the image processing means, wherein you divide the transmitted light image of the composite image or the glass substrate instead of the glass substrates of images sequentially captured in a plurality of defect detection area claim 12, 14, 15, or 16 The glass substrate defect inspection apparatus described.   The manufacturing method of the glass substrate which has the process of test | inspecting the defect of a glass substrate with the defect inspection method as described in any one of Claims 1 thru | or 10. The manufacturing method of a glass substrate which has the process of carrying out a defect inspection of the glass substrate with the defect inspection apparatus as described in any one of Claims 11 thru | or 17 . The glass substrate, according to claim 18 or 19 glass substrate manufacturing method according a glass substrate for a magnetic recording medium.

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