JP2010048745A - Defect inspection system and defect inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a defect by discriminating efficiently whether a defect exists on a plate-like body or not, in a manufacture line or the like of the plate-like body having transparency such as a glass plate. <P>SOLUTION: When photographing a bright field image by the first camera from transmitted light projected from the first linear light source and transmitted through the plate-like body, a knife edge-shaped optical path shielding member is provided on a position in front of the first camera in an optical path for the transmitted light of the first camera. A bright part domain is searched for from inside the bright field image by using as a threshold, a high signal value in comparison with a signal value of a background component of the bright field image from inside the photographed bright field image, and when extracting a bright part domain as a result of search, it is discriminated by using the bright part domain whether a defect domain exists on the plate-like body or not. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a defect inspection system and a defect inspection method for detecting defects present in a plate-like body such as a glass plate having transparency.

Today, glass plates are used in electronic devices such as flat panel displays, and therefore, there is a strong demand for glass plates that are thin and have very few or no defects such as bubbles.
Defects such as bubbles and scratches on the surface of the glass plate can be reduced, but they cannot always be completely removed. For example, parts of the glass plate where bubbles are present are removed in the inspection process. Treatment is necessary. For this reason, conventionally, various apparatuses for inspecting defects such as bubbles existing in a transparent plate-like body such as a manufactured glass plate have been proposed.

  For example, as shown in FIG. 6, a linear light source 52 longer than the width of the glass plate G is provided on one side of the conveyed glass plate G, and light is projected onto the glass plate G with a predetermined light intensity. A bright field image of the transmitted light that has passed through G is taken by a line sensor type camera 54 provided on the other side, and this image is sent to the processing unit 56. The processing unit 56 extracts a dark area included in the bright field image and extracts it as a defective area. At this time, the linear light source 52 that projects light onto the glass substrate G is made to be substantially parallel light using a long and narrow slit extending in the width direction of the glass plate G in order to capture an image with a line sensor type camera 54. Thereby, the defect of the glass plate G conveyed can be detected.

  On the other hand, Patent Document 1 below proposes a defect detection method for detecting a defect in a transparent plate. In this detection method, an illuminator that illuminates at an angle close to perpendicular to the plane of the plate-like body and an illuminator that illuminates at an angle close to parallel are provided, and image processing of an image obtained using these illuminators is performed. By performing the above, it is said that defects existing on the surface and inside of the plate-like body can be detected.

JP 2002-214158 A

  In the defect detection method described in Patent Document 1 and the method shown in FIG. 6 described above, it is not possible to distinguish between defects present on the surface of the glass plate and defects present inside. Furthermore, as described in Patent Document 1, if two illuminators are used to change the illumination method and shoot, it is not possible to detect a defect online from a glass plate conveyed at a constant speed. For this reason, there exists a problem that the said defect detection method cannot be implemented on the production line of a glass plate.

  Accordingly, the present invention provides a defect inspection system and a defect inspection method that can be used effectively in a production line for a plate-like body having transparency, such as a glass plate, in order to solve the above problems. An object is to provide a defect inspection system and a defect inspection method capable of efficiently determining and detecting whether or not a defect exists in a body, and to provide a method for manufacturing a plate-like body using this inspection method And

  In order to solve the above-described problems, the present invention provides a defect inspection system for detecting a defect present in a transparent plate-like body, the first linear light source projecting on the surface of the plate-like body, A first camera that collects the transmitted light that has passed through the plate-like body to capture a bright-field image, and a front surface of the first camera in the optical path of the transmitted light of the first camera. A signal that is higher than the signal value of the background component of the bright-field image from among the bright-field images photographed by the first defect inspection device having a knife-edge-shaped optical path shielding member and the first camera. When a bright area is searched from the bright field image using the value as a threshold, and a bright area is extracted as a result of the search, a defect area exists in the plate using the bright area. A defect inspection system comprising: a processing device that determines whether or not to perform That.

In this case, the first light source is a linear light source, and an imaging lens for forming an image of a plate-like body is provided on the front surface of the light receiving surface of the first camera. The first camera is defined as an illumination light emission effective angle that is a half of the divergence angle of the transmitted light beam of the first light source from the light source to the light receiving surface of the first camera through the imaging lens. A value representing the light emission directivity of the first light source is defined as an angle of view which is a half of the expected angle of the visual field range from the position of the light receiving surface to the irradiation surface of the first light source through the imaging lens. When α is set, a value obtained by multiplying the ratio of the angle of view with respect to the illumination light emission effective angle by a value α representing the light emission directivity of the first light source is greater than 2, a first condition, and the optical path shielding member From the light receiving surface that can be a surface orthogonal to the optical axis of the imaging lens at the transmitted light passing position. When the circle of confusion that is the visual field range is determined, the second condition is such that the area of the portion where the circle of confusion is blocked by the optical path shielding member is 43 to 57% of the area of the circle of confusion. Preferably, the first light source, the imaging lens, and the first camera are set. For example, the aperture value of the first camera, the distance between the first camera and the plate, the plate and the first so as to satisfy the first condition and the second condition A distance to the light source and a light emission width of the first light source are determined.
In particular, it is preferable to arrange the first camera so that the light receiving element of the first camera faces the first light source with the plate-shaped body interposed therebetween. Here, arranging so as to face each other means arranging the light receiving elements of the first camera so as to be positioned in the direction of the maximum light intensity of the first light source with the glass plate G interposed therebetween.

In addition to the first defect inspection apparatus, the plate-shaped body to be inspected by the first defect inspection apparatus receives illumination light reflected from the plate-shaped body and inspects the defect. The second defect inspection apparatus has a second light source for irradiating illumination light onto the surface of the plate-like body, and collects reflected light emitted from the surface of the plate-like body. A second camera provided on the same side as the second light source as viewed from the plate-like body, and the processing device is photographed by the second camera. If a dark area in the image reflected by the plate-like body is extracted from the bright-field reflected image, and this dark area is close to the bright area, it is determined that a defect exists in the plate-like body. It is preferable.
At this time, the processing device determines the thickness of the plate-like body based on the positional deviation between the dark portion area in the image reflected by the plate-like body and the dark portion in the image reflected by the other surface of the plate-like body. It is preferable to obtain defect position information in the vertical direction.

The plate-like body is transported and moved in one direction, and the first defect inspection apparatus and the second defect inspection apparatus are the first defect inspection apparatus and the second defect inspection apparatus. It is preferable that it is provided on the upstream side. However, the first defect inspection apparatus may be provided on the downstream side of the second defect inspection apparatus.
Here, it is preferable that the first defect inspection apparatus and the second defect inspection apparatus are provided adjacent to each other in the transport direction. This is because, when the distance between the first defect inspection apparatus and the second defect inspection apparatus is shorter, defect detection and identification can be processed within a shorter time than when the distance is longer.

  Further, the present invention is a defect inspection method for detecting a defect present in a transparent plate-like body, wherein the plate-like body is projected from a first linear light source onto the surface of the plate-like body. When the transmitted light that has passed is collected and a bright-field image is taken by the first camera, a light path shielding in the form of a knife edge is provided at the position in front of the first camera in the optical path of the transmitted light of the first camera. A bright part is picked up from a bright-field image by setting a signal value higher than the signal value of the background component of the bright-field image as a threshold from the bright-field image photographed by the first camera. When a bright area is extracted as a result of the search, it is determined whether or not a defect area exists in the plate using the bright area caused by this refractive error. A feature defect inspection method is provided.

  The present invention is not particularly limited by the thickness of the plate-like body. For example, in a flat panel display (FPD), the present invention is applied to a liquid crystal display (LCD) including a thin plate type, and the thickness is 0.1. In the case of up to 0.7 mm, plasma display panels (PDP), etc., those having a thickness of 1 mm or more, for example, those having a thickness of 1.8 mm, those having a thickness of 2.8 mm, and further plate glass for building materials And can be applied to the production of a transparent article having an intermediate form of a plate-like body.

In the defect inspection system and the defect inspection method of the present invention, a knife edge-shaped optical path shielding member is provided at a position in front of the first camera in the optical path of the transmitted light of the first camera, and the first camera captures the image. From the bright field image, a bright area is extracted from the bright field image using a signal value higher than the signal value of the background component of the bright field image as a threshold, and the extracted bright area is By using it for detecting a defect area existing in the plate-like body, it is possible to efficiently determine and detect whether the defect exists in the plate-like body.
In particular, a first condition in which a value obtained by multiplying a ratio of an angle of view with respect to an effective illumination emission angle by a value α (a numerical value between 0 and 1) representing the light emission directivity of the first light source is greater than 2, and an optical path shielding member The optical system of the first camera is set so as to satisfy the second condition in which the area of the portion where the circle of confusion is blocked is set to 43 to 57% of the area of the circle of confusion. Thus, the bright part can be effectively generated in the bright field image. In particular, the defect inspection can be performed more effectively by providing the first light source used for measurement and the first camera so as to face each other across the glass plate G.
Further, the second light source for irradiating illumination light onto the surface of the plate-like body, and the reflected light obtained by irradiating and reflecting on the surface of the plate-like body is collected, and a bright field reflection image is photographed. The second camera provided on the same side as the second light source when viewed from the body, and the processing device is configured to obtain a plate-like body from a bright-field reflection image photographed by the second camera. When the dark area in the image reflected by the surface is extracted and this dark area is in close proximity to the bright area, the plate-like body is formed based on the positional deviation between the real image of the defect and the mirror image of the defect. Position information in the thickness direction of the defect located can be obtained.

Hereinafter, the defect inspection system and the defect inspection method of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.
A defect inspection system 10 shown in FIG. 1 includes a first defect inspection device 12, a second defect inspection device 14, and a processing device 16.
The first defect inspection device 12 and the second defect inspection device 14 are provided in this order from the upstream side along the conveyance path of the glass sheet G. The processing device 16 is a device that processes the images obtained by the first defect inspection device 12 and the second defect inspection device 14 and performs defect detection.
The glass plate G is a long plate material that is taken out of the melting furnace and has a predetermined thickness, and is conveyed on a plurality of drive rollers 18 provided in a conveyance path.

The first defect inspection apparatus 12 is an apparatus that is located on the most upstream side of the defect inspection system 10 on the conveyance side and inspects defects on the glass sheet G.
Specifically, the first defect inspection apparatus 12 transmits the first linear light source 20 that projects light from the drive roller 18 side (lower side) to the surface of the glass plate G and the glass plate G that has passed through. A first camera 22 that collects light and captures a bright-field image, and a knife-edge optical path provided at a position in front of the first camera 22 in the optical path of the transmitted light of the first linear light source 20 And a shielding member 24.

  The first linear light source 20 is an LED light source that emits substantially parallel light, and the exit of the first linear light source 20 is along the width direction of the glass plate G (the direction perpendicular to the paper surface in FIG. 1). It extends linearly. The exit of the first linear light source 20 is provided, for example, at a position 100 to 900 mm away from the surface of the glass plate G, and the width L (see FIG. 2) along the light source transport direction is, for example, 1 to 20 mm. Set to In addition, it is preferable that the 1st linear light source 20 is provided away from the surface of the glass plate G at the point which does not require high position accuracy. The type of light in the LED light source is not particularly limited, and white is preferably used, but may be red, blue, green, or the like. Specifically, the LED light source includes a light emitting source (not shown) that emits light, a Fresnel lens (not shown) that makes emitted light substantially parallel light, and a diffusion plate (not shown) that makes light intensity substantially uniform. And a slit plate (not shown) for narrowing the emission of light. Thereby, the first linear light source 20 emits substantially parallel light having substantially uniform light intensity. In addition, even if a Fresnel lens, a diffuser plate, and a slit plate are used as described above, the light intensity is not necessarily uniform and the light cannot be made parallel, the light intensity has directional characteristics, and the light spreads. In consideration of the directivity of the light intensity at this time, a value representing the directivity is α.

The first camera 22 is a line sensor type camera that is provided at a position facing the first linear light source 20 with the glass plate G interposed therebetween and reads transmitted light that has passed through the glass G directly on the light receiving surface. A plurality of first cameras 22 are provided in the direction perpendicular to the paper surface in FIG. 1 and photograph the same position in the transport direction. In addition, the plurality of cameras have mutually different viewing ranges in the width direction of the glass plate G. In the inspection part of the glass plate G, it is arranged so that there is no non-inspection area.
The first camera 22 is provided such that the light receiving surface comes to a position where the focusing lens 23 (see FIG. 2) of the first camera 22 is in focus, for example, 200 to 400 mm away from the surface of the glass plate G. It is done. The first camera 22 includes an optical system including an imaging lens 23 and a diaphragm that adjusts an aperture, which is not illustrated. The image data obtained by the first camera 22 is sequentially sent to the processing device 16 every time it is read in a line shape.

The optical path shielding member 24 is a knife edge-shaped member that blocks a part of the optical path at the position of the front surface of the first camera 22 in the optical path of the transmitted light from the glass G. The tip portion in the optical path is sharpened so as to form a blade. The optical path shielding member 24 is provided at a position on the front surface of the optical system (imaging lens 23) of the first camera 22, for example, at a position 1 to 5 mm away. The part that holds the optical path shielding member 24 is provided with a mechanism that allows the optical path shielding member 24 to move in the X direction so as to cross the optical path. At that time, when a circle of confusion representing the field of view as viewed from the light receiving surface, which can be a surface orthogonal to the optical axis of the imaging lens 23 in the first camera 22 at the passing position of the transmitted light of the optical path shielding member 24, is determined. The area of the portion where the circle of confusion is blocked by the optical path shielding member 24 corresponds to 43 to 57% of the area of the circle of confusion, and preferably corresponds to about 50%. If it is less than 43%, a bright field described later is unlikely to occur in the bright field image, and if it exceeds 57%, a dark field image tends to be formed.
Such a range for blocking the optical path can be realized by adjusting the distance between the light shielding member 24 and the glass plate G and the aperture value of the first camera 22, for example. By setting the range for blocking the optical path to this range, as will be described later, the bright region is efficiently formed in the vicinity of the dark region created by defects such as bubbles existing in the bright field image. Because.

In this case, when the value representing the light emission directivity of the first linear light source 20 is α, the value obtained by multiplying the ratio of the field angle φ to the illumination light emission effective angle θ shown in FIG. It is preferable that The effective illumination emission angle θ is a light flux of transmitted light from the first linear light source 20 that reaches the light receiving surface of the light receiving element of the first camera 22 through the imaging lens 23 from the first linear light source 20. The half of the spread angle. The angle of view φ ranges from the position of the light receiving surface of the light receiving element of the first camera 22 through the imaging lens 23 (using the effective aperture d of the lens) to the irradiation surface of the first linear light source 20. Is half of the prospective angle.
Here, the value α representing the light emission directivity of the first linear light source 20 has an azimuth angle with the direction perpendicular to the irradiation surface of the light source as the azimuth angle of 0 degrees on the horizontal axis, as shown in FIG. The vertical axis represents the average value of relative light intensity when the value of maximum light intensity is 1.

  Furthermore, as shown in FIG. 2, the first camera 22 is disposed so that the light receiving element of the first camera 22 faces the first linear light source 20 with the glass plate G interposed therebetween. preferable. Note that d in FIG. 2 is an effective aperture of the imaging lens 23 and is represented by f / F (f is a focal length, and F is an F value). As described above, the illumination emission effective angle θ and the angle of view φ used in the present invention are geometrically determined based on the setting and arrangement of each device as shown in FIG.

  Such a first defect inspection apparatus 12 can easily detect defects such as minute bubbles present in the glass plate G.

The second defect inspection apparatus 14 includes a second light source 28 and a second camera 30. The 2nd defect inspection apparatus 14 illuminates a glass plate from one side with respect to the glass plate G test | inspected as a test object of a 1st defect inspection apparatus, and reflects on the surface and back surface of the glass plate G at this time It is a device that receives the illuminated light with the second camera 30 and inspects for defects.
In addition to the detection result of the first defect inspection apparatus 12 described above, the detection result of the second defect inspection apparatus 14 is combined and comprehensively evaluated, thereby more accurately identifying defects present in the glass plate G. Now it can be done accurately.

  The second light source 28 is an LED light source that emits substantially parallel light to the surface of the glass plate G, and makes light incident from a direction inclined with respect to the surface of the glass plate G. The second light source 28 extends in a direction perpendicular to the paper surface of FIG. The type of light in the LED light source used for the second light source 28 is not particularly limited, and white is preferably used, but may be red, blue, green, or the like. Specifically, the LED light source includes a light emitting source (not shown) that emits light, a Fresnel lens (not shown) that makes emitted light substantially parallel light, and a diffusion plate (not shown) that makes light intensity substantially uniform. And a slit plate (not shown) for narrowing the emission of light. As a result, the second linear light source 28 emits substantially parallel light having substantially uniform light intensity.

  The second camera 30 is a line sensor type camera that collects reflected light emitted from the surface of the glass G and captures a bright-field reflected image. The second camera 30 is provided on the same side as the second light source 28 when viewed from the glass plate G.

  The image photographed by the second camera 30 is an image that is illuminated by the second light source 28 and reflected by the back surface of the glass G, and is an image in which a defect area existing in the glass plate G becomes a dark part. In this image, after entering the surface of the glass plate G from a direction inclined with respect to the surface of the glass plate G and reflecting on the back surface of the glass plate G, the defect region passes through the optical path of the reflected light. After the actual image of the defect that can be formed and the incident light incident on the surface of the glass plate G from the direction inclined with respect to the surface of the glass plate G pass through the defect region in the optical path in the glass plate G, the glass plate G And a mirror image of defects formed by reflection on the back surface of the film. The image data obtained by the second camera 30 is sent to the processing device 16 every time it is read in a line shape.

The processing device 16 uses the image data sent from the first defect inspection device 12 and the second defect inspection device 14 to detect a defect on the glass plate G, identify the type of the defect, and also detect the defect glass. It is also an apparatus for specifying the position of the plate G in the thickness direction. A display 32 is connected to the processing device 16, and the display 32 includes images, defect detection results, identification results, or defect positions obtained by the first defect inspection device 12 and the second defect inspection device 14. The specific result is displayed on the screen.
As described above, the image obtained by the first defect inspection apparatus 12 is a bright field image, and the defect of the glass plate G appears as a dark part in the image due to irregular reflection of the defect region. Further, as described above, a knife-edge-shaped optical path shielding member 24 that blocks a part of the optical path is provided immediately before the optical system of the first camera 22, so that the optical path shielding member 24 allows the image to be displayed. A bright area is formed so as to face the dark area in the vicinity or to face and contact each other. The bright portion is generated due to a refractive error in the defective portion, and has a higher brightness than the background portion of the bright field image.

FIG. 4A is a schematic diagram of an example of a defect image when the optical path shielding member 24 is in the optical path. As shown in FIG. 4 (a), a bright part is formed facing the dark part region in close proximity. On the other hand, FIG. 4B is a schematic diagram of an example of a defect image when the optical path shielding member 24 does not exist in the optical path (does not block light). As shown in FIG. 4B, the bright part facing the dark part region is not formed. In the bright field image, as shown in FIG. 4 (a), the bright part is formed so as to face the dark part region in close proximity to the surface of the glass plate G due to bubbles or foreign matters existing inside. It is considered that the surface of the glass plate G becomes uneven, and the refractive error of the glass plate G slightly changes. In fact, a bright portion as shown in FIG. 4A is not formed by scratches or foreign matter adhering to the surface of the glass plate G.
For this reason, in the bright field image, the processing device 16 sets a threshold value higher than the value of the image data of the background portion in the bright field image, and extracts an area that is equal to or larger than the threshold value as the bright part area. Since the image data sent from the first camera 22 is one-dimensional image data that has passed through the inspection position and is read by the line sensor type camera, the processing device 16 has a plurality of lines (for example, 500 lines). ) Image data is accumulated and an image of a certain surface area is obtained, the extraction of the bright area is started. The position information of the extracted bright area is used as follows when detecting a defective area existing on the glass plate G.

  The image data obtained by the second defect inspection apparatus 14 and sent to the processing apparatus 16 is bright-field reflection image data, and is an image in which the defect portion is a dark area. As described above, the real image and mirror image of the defect appear as dark portions. Depending on the position in the thickness direction of the glass plate G where the defects of the glass plate G are present, a positional shift occurs between the real image and the mirror image of the defect. For example, when the defect is located near the back surface of the glass plate G, the amount of positional deviation between the real image and the mirror image is small, and when the defect is located near the surface, the amount of positional deviation between the real image and the mirror image is large.

Therefore, the processing device 16 specifies the position of the defective glass plate G in the width direction using the information on the extracted bright area. Furthermore, using this position in the width direction, the time at which an image of the same portion of the glass plate G appears between the image obtained by the first defect inspection device 12 and the image obtained by the second defect inspection device 14. Based on the amount of deviation, the real image of the defect obtained by the second camera 30 and the dark area of the mirror image are detected. The time lag amount is known because the distance in the conveyance direction between the measurement position of the first defect inspection apparatus 12 and the measurement position of the second defect inspection apparatus 14 and the conveyance speed of the glass G are known. Can be obtained from
Extraction of the dark area is performed using a preset threshold value.
Next, the amount of positional deviation between the center position of the real image and the center position of the mirror image is obtained, and the position of the defect in the glass plate G in the thickness direction is calculated based on the amount of positional deviation.
Further, the processing device 16 obtains the size of the dark area using the real image of the defect obtained by the second camera 30, and estimates the size of the defect from the size of this area. The processing device 16 extracts a dark area using a preset threshold value without using the information on the bright area independently of the process based on the information on the bright area.

The processing device 16 uses the information of the extracted dark area and the bright area to determine whether the bright area and the dark area face each other in close proximity, and the calculated defects of the glass plate G. The type of defect is specified using the position in the thickness direction, the size of the defect and the feature amount of the defect obtained from the extracted dark area. Preferably, by identifying the shape of the defect from the bright and dark areas in the bright-field transmission image and the dark area in the bright-field reflection image, the type of defect, for example, a defect due to bubbles, a defect due to foreign matter, Or it estimates by dividing into a crack etc.
Defects such as foreign matter and scratches on the surface of the glass plate G do not form bright portions in the bright field image obtained from the first defect inspection apparatus 12.

In the first defect inspection apparatus 12, it is preferable that the following conditions be satisfied in order for a bright part in the bright-field image that is close to and faces the dark area of the defect to appear effectively.
That is, in the arrangement of each part shown in FIG. 2, the first camera 22 and the first camera 22 are set so that the value obtained by multiplying the ratio of the field angle φ to the illumination light emission effective angle θ by the value α satisfies the first condition larger than 2. The distance between the glass plate G, the distance between the glass plate G and the first linear light source 20, and the irradiation width L of the first linear light source are set.
Further, when the circle of confusion that defines the edge of the field of view as viewed from the light receiving surface, which is formed on the surface orthogonal to the optical axis of the imaging lens 23 at the arrangement position of the optical path shielding member 24, is determined, The aperture value of the first camera 22 and the distance between the first camera 22 and the glass plate G so that the area of the blocked portion satisfies the second condition of 43 to 57% of the area of the circle of confusion. The distance is set.
Further, the first camera 22 is arranged so that the light receiving element of the first camera 22 is positioned in the direction of the maximum light intensity of the first linear light source 20 with the glass plate G interposed therebetween.
By arranging the devices so as to satisfy these three conditions, the bright portion can be effectively generated in the bright field image.
In addition, by reducing the F value, there is a disadvantage that the subject focal depth in photographing becomes shallow and the image is likely to be out of focus. For this reason, in order to extract a bright part efficiently, F5.6-F11 are preferable, and the value which multiplied the value (alpha) in the range of the width L 1-20 mm of the light emission part 34 of the 1st camera 20 is the said. Preferably it is greater than 2.

In the tables shown in FIGS. 5A and 5B, the numerical value of the effective illumination light emission angle θ in which the width L of the light emitting portion 34 of the first camera 20 is determined by L = 1 mm, 3 mm, 4 mm, 5 mm, and 7 mm; The value of the angle of view φ determined by the F value is shown, and the corresponding column of each table shows the value obtained by multiplying φ / θ including the value of α of the first light source 20. When the value α is approximately 1 in the range surrounded by the thick frame in the tables shown in FIGS. 5A and 5B, the value of α · φ / θ shown in FIG. It was confirmed that the bright part appeared effectively. Thus, it can be said that when the value α of the first linear light source 20 is smaller than 1 (in consideration of the light emission directivity), the bright portion appears effectively under the condition that α · φ / θ is larger than 2.
The distance from the glass plate G to the surface of the imaging lens 23 of the first camera 22 was 380 mm. The illumination WD from the irradiation surface of the first linear light source 20 to the measurement position of the glass plate G is 200 mm in FIG. 5A and 400 mm in FIG. At this time, the area of the part where the circle of confusion is blocked by the optical path shielding member 24 is set to 50% of the area of the circle of confusion.

  In such a defect inspection system 10, the glass plate G is irradiated with the parallel light from an oblique direction, and defects that have been missed by the conventional automatic defect inspection similar to the schlieren imaging method can be extracted with high accuracy and cannot be repaired. This is effective in that the defects of the glass plate G can be distinguished. Thereby, the glass plate G can be cut out to a predetermined size so as to avoid a defective portion that cannot be repaired.

  As described above, the defect inspection system and the defect inspection method of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments and examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course.

It is a figure explaining the schematic structure of one Embodiment of the defect inspection system and defect inspection method of this invention. It is a figure explaining illumination light emission effective angle (theta) and field angle (phi) in the defect inspection system of this invention. It is a figure explaining (alpha) used for the defect inspection system of this invention. (A) is a figure which shows typically an example of the image obtained with the 1st defect inspection apparatus of this invention, (b) is an example of an image obtained with the bright field image by normal transmitted light typically FIG. (A), (b) is a figure explaining the preferable range for producing | generating a bright part in the 1st defect inspection apparatus of the defect system shown in FIG. It is a figure explaining the schematic structure of the conventional defect inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Defect inspection system 12 1st defect inspection apparatus 14 2nd defect inspection apparatus 16 Processing apparatus 18 Drive roller 20 1st linear light source 22 1st camera 23 Imaging lens 24 Optical path shielding member 28 2nd light source 30 Second camera 32 Display 34 Light emitting portion

Claims (6)

A defect inspection system for detecting defects present in a plate having transparency,
A first light source that projects the surface of the plate-like body;
A first camera that collects the transmitted light that has passed through the plate-like body to capture a bright-field image;
A first defect inspection apparatus comprising: a knife edge-shaped optical path shielding member provided at a position in front of the first camera in an optical path of transmitted light of the first camera;
A bright area is searched from the bright field image by using a signal value higher than the signal value of the background component of the bright field image as a threshold from the bright field image captured by the first camera. As a result, when a bright area is extracted, a defect inspection apparatus comprising: a processing device that determines whether or not a defective area exists in the plate-like body using the bright area. system. The first light source is a linear light source;
An imaging lens for forming an image of a plate-like body is provided on the front surface of the light receiving surface of the first camera.
A half of the divergence angle of the light beam transmitted through the first light source from the first light source through the imaging lens to the light receiving surface of the first camera is set as an effective illumination light emission angle. The angle of view is a half of the expected angle of the visual field range from the position of the light receiving surface of one camera to the irradiation surface of the first light source through the imaging lens, and the light emission directivity of the first light source is When the value to be represented is α, a value obtained by multiplying the ratio of the angle of view to the illumination light emission effective angle by the value α representing the light emission directivity of the first light source is greater than 2,
When a circle of confusion, which is a visual field range viewed from the light receiving surface formed on a surface orthogonal to the optical axis of the imaging lens, is determined at the passing position of the transmitted light of the optical path shielding member, the confusion circle is formed by the optical path shielding member. The first light source, the imaging lens, and the first camera are set so as to satisfy the second condition that the area of the portion where the light is blocked is 43 to 57% of the area of the circle of confusion The defect inspection system according to claim 1. In addition to the first defect inspection apparatus, a second object for inspecting a defect by receiving illumination light reflected from the plate-like body with respect to a plate-like object to be inspected by the first defect inspection apparatus. Have defect inspection equipment,
The second defect inspection apparatus includes:
A second light source for illuminating the surface of the plate-like body with illumination light;
A second camera provided on the same side as the second light source as viewed from the plate-like body, which collects reflected light obtained by irradiation and reflected by the surface of the plate-like body and shoots a bright-field reflection image; Have
The processing device extracts a dark area in the image reflected by the plate-like body from a bright-field reflected image captured by the second camera, and the dark area is close to the bright area. The defect inspection system according to claim 1, wherein when facing each other, it is determined that a defect exists in the plate-like body.   The processing device obtains position information in a thickness direction of a defect located on a plate-like body based on a positional deviation between a real image of a defect formed as a defect image and a mirror image of the defect in the bright field reflection image. Item 4. The defect inspection system according to Item 3. The plate-like body moves in one direction and moves,
The first defect inspection apparatus and the second defect inspection apparatus, wherein the first defect inspection apparatus is provided on the upstream side of the second defect inspection apparatus. The defect inspection system according to item. A defect inspection method for detecting defects present in a plate having transparency,
When projecting a bright-field image with a first camera by projecting light from the first linear light source onto the surface of the plate-like body, collecting the transmitted light that has passed through the plate-like body,
Shooting by providing a knife edge-shaped optical path shielding member at a position in front of the first camera in the optical path of the transmitted light of the first camera,
A bright area is searched from the bright field image by using a signal value higher than the signal value of the background component of the bright field image as a threshold from the bright field image captured by the first camera. As a result, when a bright area is extracted, it is determined whether or not a defective area exists in the plate-like body using the bright area.