Inspection equipment and inspection method

Abstract

This invention provides a technology for measuring the depth from the first main surface of a transparent plate to a defect. [Solution] The inspection device measures the location of a defect in a transparent plate having a first main surface and a second main surface facing the opposite direction to the first main surface. The inspection device includes a transport device for transporting the transparent plate, a first camera having a first optical axis intersecting the first main surface, a second camera having a second optical axis intersecting the first main surface at a different angle from the first optical axis, and an image processing device that determines the location of the defect in a first direction along the first optical axis based on the difference in timing when the first camera and the second camera image the same defect. The image processing device determines the first direction position of the first main surface based on the first direction position of the defect adhering to the first main surface, and determines the depth from the first main surface to the defect based on the first direction position of the first main surface.

Description

[Technical Field]

[0001] The present disclosure relates to an inspection apparatus and an inspection method. [Background Art]

[0002] The defect detection method described in Patent Document 1 detects defects in glass using two cameras. The angle between the optical axis of one camera and the normal to the glass surface is, for example, 0 degrees. The angle between the optical axis of the other camera and the normal to the glass surface is, for example, 30 degrees. The depth of the defect is detected from the difference between the times at which the defect is detected by the two cameras, or the like. [Prior Art Literature] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-open No. Hei 7-113757 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The technology described in Patent Document 1 is a technology for measuring the distance from the intersection of the optical axes of two cameras to a defect. Therefore, as shown in FIG. 2 of Patent Document 1, if the intersection of the optical axes of the two cameras is aligned with the glass surface in advance, the depth from the glass surface to the defect can be detected.

[0005] However, due to camera installation errors or other factors, the intersection of the optical axes of the two cameras may be separated from the glass surface. In this case, the technology described in Patent Document 1 cannot detect the depth from the glass surface to the defect. This is because, unlike defects, glass transmits light, and thus the position of the glass surface cannot be identified.

[0006] An embodiment of the present disclosure provides a technique for measuring the depth from a first main surface of a transparent plate to a defect. [Means for Solving the Problem]

[0007] An inspection apparatus according to one embodiment of the present disclosure measures the location of a defect in a transparent plate having a first main surface and a second main surface facing opposite directions to the first main surface. The inspection apparatus includes a transport device for transporting the transparent plate, a first camera having a first optical axis intersecting the first main surface and imaging the transparent plate while the transparent plate is being transported by the transport device, a second camera having a second optical axis intersecting the first main surface at an angle different from the first optical axis and imaging the transparent plate while the transparent plate is being transported by the transport device, and an image processing device that determines the location of the defect in a first direction along the first optical axis based on the difference in timing between when the first camera and the second camera image the same defect. The image processing device determines the first directional position of the first main surface based on the first directional position of the defect adhering to the first main surface, and determines the depth from the first main surface to the defect based on the first directional position of the first main surface. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, the depth from the first main surface of the transparent plate to the defect can be measured. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a side view showing an inspection apparatus according to one embodiment. [Figure 2] Figure 2(A) shows the first and third directional positions of each defect in a predetermined section in the second direction; Figure 2(B) shows the first and second directional positions of each defect in a predetermined section in the third direction; Figure 2(C) is a frequency distribution diagram of the number of defects measured for each first directional position; Figure 2(D) shows the depth and third directional position of each defect in a predetermined section in the second direction; and Figure 2(E) shows the depth and second directional position of each defect in a predetermined section in the third direction. [Figure 3] Figure 3 is a side view showing the inspection apparatus according to the first modified example. [Figure 4] Figure 4 shows an example of measurement values ​​from a displacement gauge. [Figure 5]Figure 5 is a side view showing an inspection device relating to the second modified example. [Figure 6] Figure 6 shows an example of an image captured by the first camera. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, identical or similar components are denoted by the same reference numerals, and their descriptions may be omitted. In each drawing, the X-axis, Y-axis, and Z-axis directions are perpendicular to each other, the X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical.

[0011] The X-axis direction includes the positive X-axis direction and the negative X-axis direction, which is the opposite direction to the positive X-axis direction. The Y-axis direction includes the positive Y-axis direction and the negative Y-axis direction, which is the opposite direction to the positive Y-axis direction. The Z-axis direction includes the positive Z-axis direction and the negative Z-axis direction, which is the opposite direction to the positive Z-axis direction. The positive Z-axis direction is upward, and the negative Z-axis direction is downward.

[0012] Referring to Figure 1, an inspection device 1 according to one embodiment will be described. For the sake of explanation, the thickness of the transparent plate 2 in Figure 1 is exaggerated compared to the diameter of the transport roller 11. The inspection device 1 measures the positions of defects 3A, 3B, and 3C. The positions of defects 3A, 3B, and 3C include at least a first directional position, and may further include a second directional position and a third directional position. The first directional position is the position in the first direction, the second directional position is the position in the second direction, and the third directional position is the position in the third direction.

[0013] The first direction is the direction along the first optical axis 21 of the first camera 20, which will be described later. The first direction may be approximately the Z-axis direction. The second direction is the direction in which the transport device 10, which will be described later, transports the transparent plate 2. The second direction may be approximately the X-axis direction. The third direction is the direction in which the multiple light-receiving elements 22 constituting the first camera 20 are lined up in a row. The third direction may be approximately the Y-axis direction.

[0014] The transparent plate 2 has a first main surface 2a and a second main surface 2b facing the opposite direction from the first main surface 2a. The transparent plate 2 only needs to transmit light used for measuring the location of defects 3C present inside the transparent plate 2. The transparent plate 2 is, for example, a glass plate. The glass plate may contain a coloring agent.

[0015] Defects 3A, 3B, and 3C may be voids that scatter light, or particles that absorb light. Particles that absorb light are, for example, metal particles or metal compound particles. Metal compound particles are, for example, chromium-based, iron-based, tin-based, platinum-based, nickel-based particles, etc.

[0016] Hereinafter, a defect 3A adhering to the first main surface 2a of the transparent plate 2 may be referred to as a surface defect 3A. Similarly, a defect 3B adhering to the second main surface 2b of the transparent plate 2 may be referred to as a back surface defect 3B. Furthermore, a defect 3C located inside the transparent plate 2 may be referred to as an internal defect 3C.

[0017] The inspection device 1 includes a conveying device 10. The conveying device 10 conveys the transparent plate 2. The conveying device 10 has, for example, a plurality of conveying rollers 11 that are spaced apart in a second direction intersecting a first direction. The conveying device 10 conveys the transparent plate 2 in the second direction by rotating the plurality of conveying rollers 11. The rotation centerlines of each of the plurality of conveying rollers 11 may be parallel to a third direction. The conveying device 10 may also be a belt conveyor. The conveying device 10 conveys the transparent plate 2 in the second direction with the first main surface 2a of the transparent plate 2 facing upward.

[0018] The inspection apparatus 1 includes a first camera 20. The first camera 20 images the transparent plate 2, for example, from above. The first camera 20 is, for example, a line sensor camera. The line sensor camera includes a plurality of light receiving elements 22 arranged in a line in a third direction intersecting the first direction and the second direction. Note that an area sensor camera can also be used as the line sensor camera. The first camera 20 has a first optical axis 21 intersecting the first main surface 2a, and images the transparent plate 2 while the transparent plate 2 is being conveyed by the conveyance device 10. The first optical axis 21 may be set for each of the light receiving elements 22.

[0019] The inspection apparatus 1 includes a second camera 30. The second camera 30 images the transparent plate 2, for example, from above. The second camera 30 is, for example, a line sensor camera. The line sensor camera includes a plurality of light receiving elements 32 arranged in a line in the third direction. Note that an area sensor camera can also be used as a line sensor. The second camera 30 has a second optical axis 31 intersecting the first main surface 2a at an angle different from that of the first optical axis 21, and images the transparent plate 2 while the transparent plate 2 is being conveyed by the conveyance device 10. The second optical axis 31 may be set for each of the light receiving elements 32.

[0020] The first optical axis 21 and the second optical axis 31 intersect the first main surface 2a of the transparent plate 2 between two adjacent conveyance rollers 11, respectively.

[0021] On a plane perpendicular to the third direction (for example, an XZ plane), an angle θ1 formed between a normal line of the first main surface 2a of the transparent plate 2 and the first optical axis 21 may be approximately 0°. On the other hand, on the plane perpendicular to the third direction, an angle θ2 formed between the normal line of the first main surface 2a of the transparent plate 2 and the second optical axis 31 may be approximately 30°. Note that the combination of θ1 and θ2 is not particularly limited, as long as θ1 and θ2 are different from each other.

[0022] On a plane perpendicular to the third direction (for example, an XZ plane), the first optical axis 21 and the second optical axis 31 intersect each other because they have different angles. The intersection point IP may be separated from the first main surface 2a of the transparent plate 2 due to factors such as an installation error of the first camera 20 and the second camera 30, or a variation in thickness of the transparent plate 2.

[0023] The inspection device 1 may include multiple camera units, each consisting of a first camera 20 and a second camera 30. The camera units are arranged without gaps in the third direction. If one camera unit cannot image the entire third direction of the transparent plate 2, multiple camera units can be used to image the entire third direction of the transparent plate 2. The image processing device 40, described later, measures the positions of defects 3A, 3B, and 3C for each camera unit.

[0024] The inspection device 1 includes an image processing device 40. The image processing device 40 is, for example, a computer. The image processing device 40 includes a processing unit such as a CPU (Central Processing Unit) and a storage unit such as memory. The storage unit stores a program for processing images captured by the first camera 20 and the second camera 30. The image processing device 40 processes the images captured by the first camera 20 and the second camera 30 by having the processing unit execute the program stored in the storage unit.

[0025] The image processing device 40 may be part of a control device that controls the operation of various devices constituting the inspection device 1, such as the transport device 10, the first camera 20, and the second camera 30. The control device includes an electronic circuit such as a CPU, FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit), and performs the various control operations described in this specification by executing instruction codes stored in memory or by designing the circuit for special purposes.

[0026] The image processing device 40 determines the positions of defects 3A, 3B, and 3C in a first direction along the first optical axis 21 based on the difference Δt in timing between the first camera 20 and the second camera 30 capturing the same defects 3A, 3B, and 3C. The first direction position of defects 3A, 3B, and 3C is expressed as the distance D from the intersection IP of the first optical axis 21 and the second optical axis 31. A negative distance D indicates that the defect is located on the opposite side of the intersection IP from the first camera 20 (for example, the lower side). A positive distance D indicates that the defect is located on the side closer to the first camera 20 (for example, the upper side) from the intersection IP.

[0027] In the images captured by the first camera 20 or the second camera 30, the brightness of defects 3A, 3B, and 3C differs from the brightness of the background. This is because defects 3A, 3B, and 3C cause scattering or absorption of light. The brightness of defects 3A, 3B, and 3C may be higher or lower than the brightness of the background, as will be explained in more detail later. The timing at which the brightness changes in the image is the timing at which defects 3A, 3B, and 3C are captured.

[0028] The first camera 20 and the second camera 30 image the first main surface 2a of the transparent plate 2 at different angles. Therefore, a difference Δt occurs in the timing when the first camera 20 and the second camera 30 image the same defects 3A, 3B, and 3C. The larger the absolute value of Δt, the larger the absolute value of D. Also, the sign of D can be determined from the sign of Δt. Therefore, the image processing device 40 can determine the first directional position of defects 3A, 3B, and 3C based on the difference Δt.

[0029] The second directional positions of defects 3A, 3B, and 3C can be determined from the time integral of the transport speed of the transparent plate 2. The transport direction of the transparent plate 2 is the second direction. Furthermore, the third directional positions of defects 3A, 3B, and 3C can be determined from the positions of the photodetectors 22 and 32 whose light reception intensity has changed, among the multiple photodetectors 22 and 32 arranged in a line in the third direction.

[0030] However, due to installation errors of the first camera 20 or the second camera 30, the intersection point IP of the first optical axis 21 and the second optical axis 31 may be separated from the first main surface 2a of the transparent plate 2. In this case, the technology described in Patent Document 1 cannot detect the depth from the first main surface 2a of the transparent plate 2 to the defects 3A, 3B, and 3C. This is because, unlike the defects 3A, 3B, and 3C, the transparent plate 2 transmits light, so the position of the first main surface 2a of the transparent plate 2 cannot be determined.

[0031] Unlike the technology described in Patent Document 1, the image processing apparatus 40 of this embodiment utilizes surface defects 3A. The image processing apparatus 40 determines the first directional position of the first main surface 2a based on the first directional position of the surface defects 3A. The surface defects 3A cause scattering or absorption of light. Therefore, the first directional position of the first main surface 2a can be determined from the first directional position of the surface defects 3A. Based on the first directional position of the first main surface 2a, the image processing apparatus 40 determines the depth from the first main surface 2a to defects 3A, 3B, and 3C.

[0032] Referring to Figure 2, a specific example of the processing of the image processing device 40 will be described. Defects 3A, 3B, and 3C are scattered not only in the first direction but also in the second and third directions. Figure 2(A) shows the first and third direction positions of each defect 3A, 3B, and 3C present in a predetermined section of the second direction. Figure 2(B) shows the first and second direction positions of each defect 3A, 3B, and 3C present in a predetermined section of the third direction. Figure 2(C) shows the frequency distribution of the number of defects 3A, 3B, and 3C present in the predetermined sections of the second and third directions, measured for each position in the first direction. In Figure 2(C), the class width of the first direction position is, for example, 0.4 mm.

[0033] First, the image processing device 40 identifies surface defects 3A from among defects 3A, 3B, and 3C based on the maximum peak P1 of the frequency distribution of the number of defects 3A, 3B, and 3C measured for each first directional position (see Figure 2(C)). Typically, the number of surface defects 3A is significantly greater than the number of back surface defects 3B and internal defects 3C.

[0034] The image processing device 40 estimates the defects contained in the maximum peak P1 as surface defects 3A. The maximum peak P1 has a predetermined width. The width of the maximum peak P1 is determined based on, for example, the full width at half maximum of the maximum peak P1. Note that the width of the maximum peak P1 may be a fixed value determined in advance through experiments or other means.

[0035] Furthermore, the image processing device 40 can also identify back-side defects 3B among defects 3A, 3B, and 3C based on a peak P2 that is separated from the maximum peak P1 by the thickness of the transparent plate 2 in the frequency distribution of the number of defects 3A, 3B, and 3C measured for each first directional position (see Figure 2(C)). Typically, the number of back-side defects 3B is greater than the number of internal defects 3C.

[0036] Next, the image processing device 40 determines a representative value for the first directional position of the surface defect 3A as the first directional position of the first main surface 2a. The representative value is, for example, the mean, median, maximum, minimum, or half of the maximum and minimum values. A representative value is used here because the transparent plate 2 vibrates, for example, due to vibrations of the transport device 10. The vibrations of the transport device 10 are caused by the runout deviation of the transport rollers 11, which will be described later.

[0037] Incidentally, as shown in Figure 2(A), the first and third directional positions of the surface defect 3A may have a negative or positive correlation. This is due to installation errors between the transport device 10, the first camera 20, and the second camera 30. However, as shown in Figure 2(B), the first and second directional positions of the surface defect 3A do not have a negative or positive correlation.

[0038] Therefore, it is preferable for the image processing device 40 to find a straight line representing the correlation between the first directional position and the third directional position of the surface defect 3A, and to set the straight line L as the representative value. When the normal of the first main surface 2a of the transparent plate 2 is inclined with respect to the first optical axis 21, the first directional position of the first main surface 2a can be accurately determined.

[0039] The image processing device 40 determines the difference between the representative value of the position of surface defect 3A in the first direction and the values ​​of the positions of defects 3A, 3B, and 3C in the first direction as the depth from the first main surface 2a to defects 3A, 3B, and 3C. Figure 2(D) shows the depth and position in the third direction of each defect 3A, 3B, and 3C located in a predetermined section in the second direction. Figure 2(E) shows the depth and position in the second direction of each defect 3A, 3B, and 3C located in a predetermined section in the third direction.

[0040] Referring to Figure 3, the inspection device 1 according to the first modified example will be described. The differences from the above embodiment will be mainly described below. The inspection device 1 is equipped with a displacement meter 50. The displacement meter 50 may be a contact type or a non-contact type, but it is preferably a non-contact type, for example, a laser displacement meter is preferred. The displacement meter 50 measures the displacement of the first main surface 2a of the transparent plate 2 in a first direction between two adjacent transport rollers 11. Multiple displacement meters 50 may be provided at intervals in a third direction.

[0041] Figure 4 shows an example of the measurement values ​​of the displacement gauge 50. The measurement values ​​of the displacement gauge 50 fluctuate periodically in the direction of transport of the transparent plate 2, that is, in the second direction. This is due to the runout deviation of the transport roller 11. The runout deviation is the radial runout of the cylindrical surface of the transport roller 11. The runout deviation is caused by the deviation between the rotational centerline of the transport roller 11 and the centerline of the cylindrical surface of the transport roller 11, among other things.

[0042] The image processing device 40 corrects the depth from the first main surface 2a to defects 3A, 3B, and 3C in accordance with the fluctuations in the measured values ​​of the displacement meter 50. This allows for accurate determination of the depths of defects 3A, 3B, and 3C. The vibration center of the measured values ​​of the displacement meter 50 should be aligned with the representative value of the first directional position of the first main surface 2a.

[0043] Referring to Figure 5, the inspection device 1 according to the second modified example will be described. The differences from the above embodiment will be mainly described below. The inspection device 1 includes a first light source 60 and a second light source 70. The first light source 60 irradiates light toward the first camera 20 with a transparent plate 2 in between. The second light source 70 irradiates light toward the second camera 30 with a transparent plate 2 in between. The first light source 60 and the second light source 70 may be rod-shaped light sources parallel to the third direction.

[0044] On the second main surface 2b of the transparent plate 2, the illuminance I2 from the second light source 70 is higher than the illuminance I1 from the first light source 60. Illuminances I1 and I2 can be measured with a general illuminance meter. Illuminances I1 and I2 are measured in accordance with JIS C7612:1985. The illuminance ratio (I2 / I1) is not particularly limited, but is, for example, 100 to 300. Illuminance I1 is, for example, 12,000 Lx to 24,000 Lx. On the other hand, illuminance I2 is, for example, 3,000,000 Lx.

[0045] The image processing device 40 determines the type of defects 3A, 3B, and 3C based on the brightness of the defects 3A, 3B, and 3C in the image captured by the first camera 20. The type includes material. Defects 3A, 3B, and 3C may be voids that scatter light, or particles that absorb light. Particles that absorb light may be, for example, metal particles or metal compound particles.

[0046] If defects 3A, 3B, and 3C are voids that scatter light, then light from the second light source 70 is scattered by defects 3A, 3B, and 3C and directed towards the first camera 20. Therefore, the brightness of defects 3A, 3B, and 3C in the image captured by the first camera 20 is higher than the brightness of the background (see Figure 6). The low brightness of the background is due to the low illuminance of the light from the first light source 60.

[0047] On the other hand, if defects 3A, 3B, and 3C are particles that absorb light, then the light from the second light source 70 is absorbed by defects 3A, 3B, and 3C and hardly reaches the first camera 20. Therefore, the brightness of defects 3A, 3B, and 3C in the image captured by the first camera 20 is lower than the brightness of the background (see Figure 6).

[0048] The following additional information is disclosed regarding the above embodiments, etc. [Note 1] An inspection device for measuring the location of a defect in a transparent plate having a first main surface and a second main surface facing the opposite direction from the first main surface, A conveying device for transporting the transparent plate, A first camera having a first optical axis intersecting the first main surface, which images the transparent plate while the transparent plate is being transported by the transport device, A second camera having a second optical axis that intersects the first main surface at an angle different from the first optical axis, and which images the transparent plate while the transparent plate is being transported by the transport device, The system includes an image processing device that determines the position of the defect in a first direction along the first optical axis based on the difference in timing between the first camera and the second camera capturing the same defect, The aforementioned image processing device is Based on the first directional position of the defect adhering to the first main surface, the first directional position of the first main surface is determined. An inspection device that determines the depth from the first main surface to the defect based on the first directional position of the first main surface. [Note 2] The aforementioned image processing device is Based on the maximum peak of the frequency distribution obtained by measuring the number of defects for each of the first directional positions, surface defects adhering to the first main surface of the transparent plate are identified among the defects. The inspection apparatus described in Appendix 1, which determines a representative value of the first directional position of the surface defect as the first directional position of the first main surface. [Note 3] The conveying device conveys the transparent plate in a second direction intersecting the first direction. The first camera and the second camera each have a plurality of light-receiving elements arranged in a third direction that intersects the first and second directions. The inspection apparatus according to Appendix 2, wherein the image processing apparatus determines a straight line representing the correlation between the position of the surface defect in the first direction and the position of the surface defect in the third direction, and sets the straight line as the representative value. [Note 4] The conveying device has a plurality of conveying rollers arranged at intervals in a second direction intersecting the first direction, and conveys the transparent plate in the second direction. The first optical axis and the second optical axis each intersect the first main surface of the transparent plate between two adjacent transport rollers. The inspection device includes a displacement meter that measures the displacement of the first main surface of the transparent plate in the first direction between the two adjacent transport rollers. The image processing device is an inspection device according to any one of the appendices 1 to 3, which corrects the depth in accordance with the fluctuation of the measured value of the displacement meter. [Note 5] A first light source that shines light toward the first camera with the transparent plate in between, A second light source that shines light toward the second camera with the transparent plate in between, Equipped with, On the second main surface of the transparent plate facing away from the first main surface, the illuminance of the light from the second light source is higher than the illuminance of the light from the first light source. The image processing apparatus is an inspection apparatus according to any one of the appendices 1 to 4, which determines the type of defect based on the brightness of the defect in the image captured by the first camera. [Note 6] An inspection method for measuring the location of a defect in a transparent plate having a first main surface and a second main surface facing opposite directions from the first main surface, The transparent plate is transported by a transport device, During the transport of the transparent plate by the transport device, the transparent plate is imaged with a first camera having a first optical axis intersecting the first main surface, During the transport of the transparent plate by the transport device, the transparent plate is imaged with a second camera having a second optical axis that intersects the first main surface at an angle different from the first optical axis, The image processing device determines the position of the defect in a first direction along the first optical axis based on the difference in timing between the first camera and the second camera capturing the same defect, The aforementioned image processing device is Based on the first directional position of the defect adhering to the first main surface, the first directional position of the first main surface is determined. An inspection method for determining the depth from the first main surface to the defect based on the first directional position of the first main surface. [Note 7] The aforementioned image processing device is Based on the maximum peak of the frequency distribution obtained by measuring the number of defects for each of the first directional positions, surface defects adhering to the first main surface of the transparent plate are identified among the defects. The inspection method described in Appendix 6, wherein a representative value of the position of the surface defect in the first direction is determined as the position of the first main surface in the first direction. [Note 8] The conveying device conveys the transparent plate in a second direction intersecting the first direction. The first camera and the second camera each have a plurality of light-receiving elements arranged in a third direction that intersects the first and second directions. The inspection method according to Appendix 7, wherein the image processing apparatus determines a straight line representing the correlation between the position of the surface defect in the first direction and the position of the surface defect in the third direction, and sets the straight line as the representative value. [Note 9] The conveying device has a plurality of conveying rollers arranged at intervals in a second direction intersecting the first direction, and conveys the transparent plate in the second direction. The first optical axis and the second optical axis each intersect the first main surface of the transparent plate between two adjacent transport rollers. The inspection method comprises measuring the displacement of the first main surface of the transparent plate in a first direction between two adjacent transport rollers using a displacement meter. The inspection method according to any one of the appendices 6 to 8, wherein the image processing device corrects the depth according to the fluctuation of the measured value of the displacement meter. [Note 10] The transparent plate is used to separate the light source from the first light source and the first camera, The transparent plate is used to separate the light source from the second light source and the second camera, It has, On the second main surface of the transparent plate facing away from the first main surface, the illuminance of the light from the second light source is higher than the illuminance of the light from the first light source. The inspection method according to any one of the appendices 6 to 9, wherein the image processing device determines the type of defect based on the brightness of the defect in the image captured by the first camera.

[0049] The inspection apparatus and inspection method relating to this disclosure have been described above, but this disclosure is not limited to the embodiments described above. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally fall within the technical scope of this disclosure. [Explanation of symbols]

[0050] 1. Inspection device 2 Transparent plate 2a 1st principal surface 2b 2nd principal surface 3A, 3B, 3C defects 10 Conveying device 20. Camera 1 21 1st optical axis 30. Second camera 31 2nd optical axis 40 Image Processing Devices

Claims

1. An inspection device for measuring the location of a defect in a transparent plate having a first main surface and a second main surface facing the opposite direction from the first main surface, A conveying device for transporting the transparent plate, A first camera having a first optical axis intersecting the first main surface, which images the transparent plate while the transparent plate is being transported by the transport device, A second camera having a second optical axis that intersects the first main surface at an angle different from the first optical axis, and which images the transparent plate while the transparent plate is being transported by the transport device, The system includes an image processing device that determines the position of the defect in a first direction along the first optical axis based on the difference in timing between the first camera and the second camera capturing the same defect, The aforementioned image processing device is Based on the first directional position of the defect adhering to the first main surface, the first directional position of the first main surface is determined. An inspection device that determines the depth from the first main surface to the defect based on the first directional position of the first main surface.

2. The aforementioned image processing device is Based on the maximum peak of the frequency distribution obtained by measuring the number of defects for each of the first directional positions, surface defects adhering to the first main surface of the transparent plate are identified among the defects. The inspection apparatus according to claim 1, wherein a representative value of the first directional position of the surface defect is determined as the first directional position of the first main surface.

3. The conveying device conveys the transparent plate in a second direction intersecting the first direction. The first camera and the second camera each have a plurality of light-receiving elements arranged in a third direction that intersects the first and second directions. The inspection apparatus according to claim 2, wherein the image processing apparatus determines a straight line representing the correlation between the first directional position and the third directional position of the surface defect, and sets the straight line as the representative value.

4. The conveying device has a plurality of conveying rollers arranged at intervals in a second direction intersecting the first direction, and conveys the transparent plate in the second direction. The first optical axis and the second optical axis each intersect the first main surface of the transparent plate between two adjacent transport rollers. The inspection device includes a displacement meter that measures the displacement of the first main surface of the transparent plate in the first direction between the two adjacent transport rollers. The inspection apparatus according to claim 1, wherein the image processing device corrects the depth in accordance with the fluctuation of the measurement value of the displacement meter.

5. A first light source that shines light toward the first camera with the transparent plate in between, A second light source that shines light toward the second camera with the transparent plate in between, Equipped with, On the second main surface of the transparent plate facing away from the first main surface, the illuminance of the light from the second light source is higher than the illuminance of the light from the first light source. The inspection apparatus according to any one of claims 1 to 4, wherein the image processing apparatus determines the type of defect based on the brightness of the defect in the image captured by the first camera.

6. An inspection method for measuring the location of a defect in a transparent plate having a first main surface and a second main surface facing the opposite direction from the first main surface, The transparent plate is transported by a transport device, During the transport of the transparent plate by the transport device, the transparent plate is imaged with a first camera having a first optical axis that intersects the first main surface, During the transport of the transparent plate by the transport device, the transparent plate is imaged with a second camera having a second optical axis that intersects the first main surface at an angle different from the first optical axis, The system includes determining the position of the defect in a first direction along the first optical axis using an image processing device, based on the difference in timing between the first camera and the second camera capturing the same defect. The aforementioned image processing device is Based on the first directional position of the defect adhering to the first main surface, the first directional position of the first main surface is determined. An inspection method for determining the depth from the first main surface to the defect based on the first directional position of the first main surface.

7. The aforementioned image processing device is Based on the maximum peak of the frequency distribution obtained by measuring the number of defects for each of the first directional positions, surface defects adhering to the first main surface of the transparent plate are identified among the defects. The inspection method according to claim 6, wherein a representative value of the first directional position of the surface defect is determined as the first directional position of the first main surface.

8. The conveying device conveys the transparent plate in a second direction intersecting the first direction. The first camera and the second camera each have a plurality of light-receiving elements arranged in a third direction that intersects the first and second directions. The inspection method according to claim 7, wherein the image processing apparatus determines a straight line representing the correlation between the position of the surface defect in the first direction and the position of the surface defect in the third direction, and sets the straight line as the representative value.

9. The conveying device has a plurality of conveying rollers arranged at intervals in a second direction intersecting the first direction, and conveys the transparent plate in the second direction. The first optical axis and the second optical axis each intersect the first main surface of the transparent plate between two adjacent transport rollers. The inspection method comprises measuring the displacement of the first main surface of the transparent plate in a first direction between two adjacent transport rollers using a displacement meter. The inspection method according to claim 6, wherein the image processing device corrects the depth in accordance with the fluctuation of the measurement value of the displacement meter.

10. The transparent plate is used to separate the light source from the first light source towards the first camera, The transparent plate is used to separate the light source from the second light source and the second camera, It has, On the second main surface of the transparent plate facing away from the first main surface, the illuminance of the light from the second light source is higher than the illuminance of the light from the first light source. The inspection method according to any one of claims 6 to 9, wherein the image processing device determines the type of defect based on the brightness of the defect in the image captured by the first camera.

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