A method and system for locating and measuring defects in glass slabs

Abstract

The application discloses a kind of positioning and measurement method and system for glass block defects, it is related to the technical field of glass quality detection, the method comprises: the glass block to be measured is placed to detection area, the lamp bead of first illumination light source is sequentially lighted, first acquisition system shoots first image, after opening second illumination light source, second image is shot, the xyz coordinates of each defect point and its corresponding are recorded by scanning complete block glass block to be measured;The coordinates of all defect points are sequentially input into second acquisition system, close first illumination light source and second illumination light source, open third illumination light source, second acquisition system sequentially moves to the corresponding position of defect point and shoots, an image is shot for each defect point to calculate the size of each defect point and correct x coordinate, computer judges result and gives the grading conclusion of glass block to be measured, as reference for further cutting.

Description

Technical Field

[0001] This invention relates to the technical field of glass quality inspection, and more specifically, to a method and system for locating and measuring defects in glass blocks. Background Technology

[0002] Optical glass blocks are highly transparent and have high uniformity in structure and performance. Different glass blocks have specific and precise optical parameters. As key optical components used in the manufacture of optical instruments such as lenses, prisms and windows, the size and quantity of internal bubbles and impurities are the main contents of quality inspection.

[0003] Currently, manufacturers detect the size and number of air bubbles inside glass blocks manually by using a flashlight to illuminate the glass from the side and then observing and judging with the naked eye. The human eye looks at the cross-section and observes bright spots as air bubbles or foreign objects. The size is judged by experienced inspectors through estimation. For those that cannot be judged, a high-magnification magnifying glass is used to assist in the judgment. This manual inspection standard is greatly affected by the subjective judgment of quality inspectors, and staring at the glass under strong light for a long time can easily cause eye fatigue and affect physical health.

[0004] The industry is still exploring automated defect detection technology. Patent CN101424646, titled "Method for Detecting Foreign Objects and Bubbles in Glass," provides a method where a laser light source illuminates the side of the glass, and a linear scan camera scans the top of the glass. Bubbles or foreign objects within the glass change the direction of light emission or transmission and are thus collected. However, this method can only determine the presence or absence of defects and cannot determine whether they are on the surface or inside, the type of defect, or the size of the collected defects. Patent CN102621160, titled "Plate Glass Foreign Object Detection Device and Detection Method," provides a method for distinguishing internal bubbles and foreign objects in plate glass using polarization, but it cannot obtain the size of the defects. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for accurately locating the position of each bubble or impurity / foreign object inside a machine using machine vision detection instead of human eye judgment.

[0006] The technical solution of this invention is: to provide a method for locating and measuring defects in glass blocks, the method comprising:

[0007] S1. Place the glass block to be tested flat in the detection area, set the first illumination source so that it faces the first side of the glass block to be tested along the x direction, set the second illumination source so that it faces the second side of the glass block to be tested along the y direction, and set the first acquisition system so that it is located on the other side of the glass block to be tested, facing the glass block to be tested and the second illumination source.

[0008] S2. Sequentially illuminate each lighting unit of the first lighting source. Each lighting unit has a different x-coordinate. Execute the following loop once for each lighting unit illuminated:

[0009] S21. The first acquisition system captures a first image, and the second illumination source is turned on to capture a second image. Each bright spot that appears simultaneously in the first image and the second image is taken as a defect point, and the x-coordinate corresponding to the illumination unit is taken as the x-coordinate of the defect point in this cycle.

[0010] S22. Determine the coordinates of each defect point on the y and z axes by the relative position of each defect point with the side and top of the glass block to be tested in the second image. The z axis is perpendicular to the x and y axes. Obtain the xyz coordinates of each defect point and turn off the first and second illumination sources.

[0011] S3. After the last lighting unit is turned off, the above loop is completed, and all defect points and their corresponding xyz coordinates are recorded.

[0012] In any of the above technical solutions, the method further includes:

[0013] S4. A second acquisition system is set up above the glass block to be tested, and a third illumination source is set up below the glass block to be tested. The coordinates of all defect points are sequentially input into the second acquisition system. The third illumination source is turned on, and the second acquisition system moves sequentially to a preset distance above the defect points to take pictures. An image is taken for each defect point to calculate the size of each defect point. The x-coordinate of the defect point is corrected according to the distance of the defect point from the center of the image. The corrected coordinates and the corresponding size are recorded and output. The computer gives a grading conclusion on the quality of the glass block to be tested based on the defect data.

[0014] In any of the above technical solutions, the third illumination source further has a striped light pattern, and the method includes irradiating the glass block with striped light and determining whether there are special foreign objects in the glass block under test based on whether the obtained image has distortion.

[0015] In any of the above technical solutions, the second acquisition system further reads the z-axis coordinates of the defect point and then focuses to the corresponding depth by adjusting its own parameters.

[0016] In any of the above technical solutions, the method further includes: when it is determined that the specific coordinates of a defect point are less than or equal to 0.5 mm from the surface of the glass block to be tested, the record of the defect point is deleted.

[0017] A system for locating and measuring defects in glass blocks is also provided. The system includes: a first acquisition system, a second acquisition system, a first illumination source, a second illumination source, a third illumination source, and the glass block to be measured.

[0018] The glass block to be tested is suspended in mid-air. The first and second illumination sources illuminate the two adjacent sides of the glass block. The first acquisition system is facing the opposite side of the second illumination source to take pictures. The second acquisition system and the third illumination source are facing the top and bottom of the glass block to be tested, respectively.

[0019] In any of the above technical solutions, the first lighting source is a strip light source having multiple lighting units arranged in a single row, each lighting unit being controlled individually;

[0020] The second lighting source is a panel light source that emits diffuse or parallel light.

[0021] In any of the above technical solutions, the first lighting source is a point light source that emits a light beam during operation, and the first lighting source is mounted on a slide rail perpendicular to the panel of the second lighting source.

[0022] In any of the above technical solutions, the third lighting source is a functional panel light source that can switch between uniform lighting and striped lighting, and can be set to illuminate a specific area or illuminate the whole.

[0023] In any of the above technical solutions, the third lighting source further includes two panel light sources, one of which emits light uniformly and the other emits light in stripes.

[0024] The beneficial effects of this invention are:

[0025] The technical solution in this invention realizes a method of replacing human eye judgment with machine vision detection, which can accurately locate the position of each bubble or impurity / foreign object inside and obtain its size. After the entire glass block is tested, it can be graded based on the number and size of defects, realizing intelligent and high-speed detection.

[0026] During inspection, a point light source perpendicular to the imaging plane is used to illuminate the glass block. Defects in the glass block cause light to refract into the camera, forming bright spots, thus identifying all defect points within a range. Then, a surface light source is turned on to illuminate the edges of the glass block. The specific coordinates of the defect points are determined by the relative positions of the bright spots and the edges. This method is more accurate in counting defect points and will not produce errors, omissions, or duplicate counts. Attached Figure Description

[0027] The advantages of the above and additional aspects of the present invention will become apparent and readily understood in the description of the embodiments in conjunction with the following drawings, wherein:

[0028] Figure 1 This is a schematic flowchart of a method for locating and measuring defects in glass blocks according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of a detection device for a system for locating and measuring defects in glass blocks according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of an image captured by a first acquisition system under a first illumination source in a method for locating and measuring defects in glass blocks according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of an image captured by a first acquisition system under a first illumination source and a second illumination source in a method for locating and measuring defects in glass blocks according to an embodiment of the present invention.

[0032] Figure 5 This is a partial schematic diagram of a detection device when the first illumination source of a system for locating and measuring defects in glass blocks according to an embodiment of the present invention is a point light source;

[0033] Figure 6 This is a schematic diagram of an image captured by a second acquisition system under a third illumination source in a method for locating and measuring defects in glass blocks according to an embodiment of the present invention.

[0034] Figure 7 This is a schematic diagram of an image captured by a second acquisition system under ordinary light, which is a third illumination source for a method of locating and measuring defects in glass blocks according to an embodiment of the present invention.

[0035] Figure 8 This is a schematic diagram of an image captured by a second acquisition system under striped light from a third illumination source in a method for locating and measuring defects in glass blocks according to an embodiment of the present invention.

[0036] Figure 9 An image captured when the second illumination source is not shielded and the image is captured using only the first illumination source and the first acquisition system, without any shielding plate on the side of the second illumination source.

[0037] Figure 10 An image captured when a shield is provided on one side of the second illumination source, and the image is acquired using only the first illumination source and the first acquisition system.

[0038] Among them, 11-first acquisition system, 12-second acquisition system, 21-first illumination source, 22-second illumination source, 23-third illumination source, 30-glass block to be tested, and 41-46-defect points. Detailed Implementation

[0039] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0040] In the following description, many specific details are set forth in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0041] like Figure 1 As shown, this embodiment provides a method and system for locating and measuring defects in glass blocks. The system includes:

[0042] The glass block to be tested, 30 mm thick, is placed flat in the testing area. Figure 2 As shown, the detection area includes a first acquisition system 11, a second acquisition system 12, a first illumination source 21, a second illumination source 22, and a third illumination source 23; wherein, the first illumination source 21 and the second illumination source 22 illuminate the two adjacent sides of the glass block 30 to be tested, the first acquisition system 11 is facing the opposite side of the second illumination source 22, and the second acquisition system 12 and the third illumination source 23 face the top and bottom of the glass block 30 to be tested, respectively.

[0043] Specifically, the glass block 30 to be tested is a square glass sheet that has already been cut; the first illumination source 21 is a strip light source with multiple LED beads arranged in a single row, and each LED bead can be individually controlled to light up; the second illumination source 22 is a panel light source that emits diffuse or parallel light; the third illumination source 23 can be a panel light source that emits uniform light, a panel light source that emits striped light, or a functional panel light source that can switch between uniform illumination and striped illumination, and can be set to illuminate a specific area or illuminate the whole; the first illumination source 21, the second illumination source 22 and the third illumination source 23 can be monochromatic light or polychromatic light, and can be implemented using LED, LCD, OLED or other light sources that can be lit.

[0044] The first acquisition system 11 can use any type of imaging system that meets the resolution requirements. When using a telecentric imaging system, there will be no perspective distortion problem in the image, and it can be used directly. When using a non-telecentric imaging system, although perspective distortion exists, the image can be adjusted using a common distortion correction algorithm according to the shooting depth.

[0045] The method for locating and measuring defects in glass blocks provided in this embodiment includes: establishing an xyz coordinate system with the arrangement direction of the lamp beads of the first illumination source 21 as the x-direction, the parallel direction of the second illumination source 22 as the y-direction, and the acquisition direction (vertical direction) of the second acquisition system 12 as the z-direction; illuminating the lamp beads at one edge of the first illumination source 21 individually, and capturing the first image by the first acquisition system 11. Since the illumination direction of the first illumination source 21 is perpendicular to the capture direction of the first acquisition system 11, defects or bubbles in the glass block will refract the light from the first illumination source 21, thus observing bright spots in the first image.

[0046] The single LED of the first illumination source 21 has a narrow illumination range, so the captured image can be regarded as a cross-sectional image of the location of the LED, thereby determining the approximate x-axis coordinates of the observed bright spot.

[0047] Next, while maintaining the illumination of a single LED bead in the first illumination source 21, the second illumination source 22 is turned on, and the first acquisition system 11 captures a second image. Each bright spot that appears simultaneously in the first and second images is taken as the defect point corresponding to the LED bead number, and the x-coordinate corresponding to the LED bead number is taken as the x-coordinate of the defect point corresponding to the LED bead number.

[0048] like Figure 3 and Figure 4 As shown, six defect points, 41-46, can be observed simultaneously in the first and second images. Since the edge of the glass block 30 under test is illuminated in the second image, the coordinates of each defect point on the y and z axes can be determined; the xyz coordinates corresponding to each defect point are recorded and saved.

[0049] Specifically, the first image is a dark field image because the backlight is not on, with a completely black background. The illumination direction of the first illumination source 21 is perpendicular to the shooting direction of the first acquisition system 11. When the light passes through the defect point, it will be refracted and appear as a bright spot in the image. Therefore, this method can find the defect point in the glass block within the illumination range of the lamp bead. The second image is a bright field image because the backlight is on. After the second illumination source 22 is turned on, the light shines directly into the first acquisition system 11. Defect points outside the illumination range of the lamp bead of the first illumination source 21 will not focus or refract the backlight to the first acquisition system 11, thus avoiding displaying other defect points in the image. The second illumination source 22 illuminates the edge of the glass block 30 under test. By the positional relationship between the bright spot in the image and the glass block 30 under test, the specific coordinates of the bright spot, which is the defect point within the lamp bead range, can be located. At the same time, in order to avoid the defect points outside this column accidentally appearing as bright spots under the illumination of the second illumination source 22 and causing repeated detection, since the devices do not move, the position of the bright spot will not change in the two images. The bright spot that appears in both the first and second images is taken as the defect point and its coordinates are recorded.

[0050] Then, the first illumination source 21 and the second illumination source 22 are turned off, and the next LED of the first illumination source 21 is turned on. The first acquisition system 11 captures the third image. While maintaining the illumination of the third image, the second illumination source 22 is turned on to capture the fourth image, and the xyz coordinates of all defect points are recorded. This process continues, with the number of LEDs in the first illumination source 21 being N, and a total of 2N images are captured.

[0051] In another embodiment of the invention, such as Figure 5 As shown, the first lighting source 21 is a point light source that emits a beam of light when working, achieving the same effect as the single lamp bead of the strip light source mentioned above. The point light source is mounted on a track and moves to simulate the effect of the lamp beads of the strip light source lighting up in sequence. The track is set perpendicular to the panel of the second lighting source 22.

[0052] A total of M defect points are recorded throughout the process. The coordinates of the M defect points are sequentially input into the second acquisition system 12. The first illumination source 21 and the second illumination source 22 are turned off, and the third illumination source 23 is turned on. The second acquisition system 12 moves to the corresponding position of each defect point to take pictures, and a total of M images are taken. The size of each bubble or impurity is calculated, and the x-coordinate of the defect point is corrected according to the distance of the bubble or impurity from the center of the image. The corrected coordinates and the corresponding size are recorded and output. The computer judges the results and gives the grading conclusion of the glass block to be tested, which serves as a reference for further cutting.

[0053] Specifically, the second acquisition system 12 is a high-precision dimensional measurement system capable of measuring bubbles or foreign objects with a size of not less than 20μm. The z-axis coordinate of a known defect point can be automatically focused to the corresponding depth. The single-shot diameter of the second acquisition system 12 is larger than the illumination range of the two first illumination source lamps 21, and it can adapt to and correct for errors in the x-coordinate. Figure 6 As shown, from left to right, there are: a bubble with a diameter of about 110.5 μm, an impurity with a diameter of about 36.2 μm, and an impurity with a diameter of about 440 μm.

[0054] Specifically, for some special foreign objects whose external contours are not sharp, such as those with a string-like shape, the changes they cause in the glass cannot be seen under ordinary surface light sources. The third illumination source 23 needs to be upgraded to a striped light to reveal the large-scale glass image distortion caused by these objects; only this range can truly be considered the size of the defect. Figure 7 and Figure 8 As shown, the impurity in the left image has a diameter of only about 1218 μm under normal light irradiation, but can reach about 2704 μm under striped light irradiation; the bubble in the right image has a diameter of only about 305 μm under normal light irradiation, but can reach about 851 μm under striped light irradiation.

[0055] In addition, high-quality optical glass blocks, as the supply material for optical components, often require the removal of the first 0.5mm of the surface. However, bubbles or impurities within this 0.5mm cannot be used to count the number of internal defects in the glass block. The method provided by this invention can obtain the specific coordinates of each bubble or defect, thereby determining whether it is within the grinding range, resulting in a more accurate and practical inspection report.

[0056] In summary, the present invention proposes a method and system for locating and measuring defects in glass blocks, comprising: placing the glass block 30 to be tested flat in the detection area, placing the first acquisition system 11 facing the glass block 30 to be tested in the x direction, illuminating the glass block 30 to be tested with the first illumination source 21 in the y direction, and placing the second illumination source 22 opposite the first acquisition system 11 and illuminating the glass block 30 to be tested.

[0057] The first illumination source 21 LED beads are lit sequentially. The first acquisition system 11 first captures the first image. When the second illumination source 22 is turned on, the second image is captured. Each bright spot that appears in both the first and second images is taken as a defect point. The x-coordinate of the LED bead is taken as the x-coordinate of the corresponding defect point.

[0058] By determining the y and z coordinates of each defect point relative to the side and top of the glass block 30 under test in the second image, the above steps are repeated to traverse the entire glass block 30 under test, and each defect point and its corresponding xyz coordinates are recorded.

[0059] After the above-mentioned shooting is completed, the coordinates of all defect points are sequentially input into the second acquisition system 12. The first illumination source 21 and the second illumination source 22 are turned off, and the third illumination source 23 is turned on. The second acquisition system 12 moves to the corresponding position of the defect point to take pictures. An image is taken for each defect point to calculate the size of each defect point. The x-coordinate of the defect point is corrected according to the distance of the defect point from the center of the image. The corrected coordinates and the corresponding size are recorded and output. The computer judges the results and gives the quality grading conclusion of the glass block to be tested, which serves as a reference for further cutting.

[0060] In addition, the applicant noted that when illuminating with only the first illumination source and acquiring images with the first acquisition system 11, setting a shield on one side of the second illumination source 22 (i.e. the other side of the glass block to be tested) or setting the back plate of the second illumination source 22 to be large enough and opaque so that it can cover and shield the side edge of the glass block 30 to be tested can help improve the image acquisition quality.

[0061] like Figure 9As shown, when there is no obstruction on one side of the second illumination source 22, the image captured by the first acquisition system 11 when only the first illumination source is used for illumination and the first acquisition system 11 is used for image acquisition will contain interference bands, which will affect the detection of bubbles.

[0062] Figure 10 As shown, this is an image captured when a shield is provided on one side of the second illumination source 22, and the image is captured using only the first illumination source and the first acquisition system 11.

[0063] contrast Figure 9 and Figure 10 It can be seen that when only the first illumination source is used for illumination and the first acquisition system 11 is used for image acquisition, whether or not a shield is set on the other side of the glass block to be tested has a huge impact on the shooting effect.

[0064] The steps in this invention can be adjusted, combined, or deleted according to actual needs.

[0065] The units in the system of this invention can be merged, divided, or deleted according to actual needs.

[0066] Although the invention has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and not intended to limit the application of the invention. The scope of protection of the invention is defined by the appended claims and may include various variations, modifications, and equivalents made to the invention without departing from the scope and spirit of the invention.

Claims

1. A method for locating and measuring defects in glass blocks, characterized in that, The method includes: S1. Place the glass block (30) to be tested flat in the detection area, set a first illumination source (21) so that it faces the first side of the glass block (30) to be tested, with the first side along the x direction, set a second illumination source (22) so that it faces the second side of the glass block (30) to be tested, with the second side along the y direction, set a first acquisition system (11) so that it is located on the other side of the glass block (30) to be tested, facing the glass block (30) to be tested and the second illumination source (22). S2. Sequentially illuminate each lighting unit of the first lighting source (21), wherein the lighting unit has a different x-coordinate, and execute the following loop once when illuminating each lighting unit: S21. The first acquisition system (11) captures a first image, and the second illumination source (22) is turned on to capture a second image. Each bright spot that appears in both the first image and the second image is taken as a defect point, and the x-coordinate corresponding to the illumination unit is taken as the x-coordinate of the defect point in this cycle. S22. Determine the coordinates of each defect point on the y and z axes by the relative position of each defect point in the second image with the side and top of the glass block (30) to be tested. The z axis is perpendicular to the x and y axes. Obtain the xyz coordinates of each defect point and turn off the first lighting source (21) and the second lighting source (22). S3. After the last lighting unit is turned off, the above loop is completed, and all defect points and their corresponding xyz coordinates are recorded. S4. A second acquisition system (12) is set above the glass block (30) to be tested, and a third illumination source (23) is set below the glass block (30) to be tested. The coordinates of all defect points are sequentially input into the second acquisition system (12). The third illumination source (23) is turned on. The second acquisition system (12) moves sequentially to a preset distance above the defect point to take pictures. An image is taken for each defect point to calculate the size of each defect point. The x-coordinate of the defect point is corrected according to the distance of the defect point from the center of the image. The corrected coordinates and the corresponding size are recorded and output. The computer gives a quality classification conclusion of the glass block (30) to be tested based on the defect data. The second acquisition system (12) reads the z-axis coordinates of the defect point and then focuses to the corresponding depth by adjusting its own parameters.

2. The method for locating and measuring defects in glass blocks as described in claim 1, characterized in that, The third illumination source (23) has a striped light pattern. The method includes irradiating the glass block with striped light and determining whether there are special foreign objects in the glass block (30) to be tested based on whether the obtained image has distortion.

3. The method for locating and measuring defects in glass blocks as described in claim 1, characterized in that, The method further includes: when it is determined that the coordinates of a defect point are less than or equal to 0.5 mm from the surface of the glass block (30) to be tested, the record of the defect point is deleted.

4. A system for locating and measuring defects in glass blocks, characterized in that, The system includes: a first acquisition system (11), a second acquisition system (12), a first illumination source (21), a second illumination source (22), a third illumination source (23), and a glass block to be tested (30); The glass block (30) to be tested is suspended in mid-air. The first lighting source (21) and the second lighting source (22) illuminate the two adjacent sides of the glass block (30) to be tested. The first acquisition system (11) takes pictures directly opposite the location of the second lighting source (22). The second acquisition system (12) and the third lighting source (23) face the top and bottom of the glass block (30) to be tested, respectively. A first illumination source (21) is set to face the first side of the glass block (30) to be tested, with the first side along the x direction; a second illumination source (22) is set to face the second side of the glass block (30) to be tested, with the second side along the y direction. The first lighting source (21) is lit sequentially, and each lighting unit has a different x-coordinate. The first acquisition system (11) captures a first image, and the second lighting source (22) is turned on to capture a second image. Each bright spot that appears in both the first and second images is taken as a defect point, and the x-coordinate of the lighting unit is taken as the x-coordinate of the defect point in this cycle. The y and z coordinates of each defect point are determined by the relative position of each defect point in the second image with the side and top of the glass block (30) to be tested. The z-axis is perpendicular to the x and y axes, and the xyz coordinates of each defect point are obtained. The first lighting source (21) and the second lighting source (22) are turned off. The second acquisition system (12) moves sequentially to a preset distance above the defect point to take pictures, takes an image of each defect point to calculate the size of each defect point, and corrects the x-coordinate of the defect point according to the distance of the defect point from the center of the image. The corrected coordinate and the corresponding size are recorded and output. The computer gives the quality classification conclusion of the glass block material (30) to be tested based on the defect data. The second acquisition system (12) reads the z-axis coordinates of the defect point and then focuses to the corresponding depth by adjusting its own parameters.

5. The system for locating and measuring defects in glass blocks as described in claim 4, characterized in that, The first lighting source (21) is a strip light source with multiple lighting units arranged in a single row, and each lighting unit is controlled individually; The second lighting source (22) is a panel light source that emits diffuse or parallel light.

6. The system for locating and measuring defects in glass blocks as described in claim 4, characterized in that, The first lighting source (21) is a point light source that emits a beam of light when it is working. The first lighting source (21) is mounted on a slide rail that is perpendicular to the panel of the second lighting source (22).

7. The system for locating and measuring defects in glass blocks as described in claim 4, characterized in that, The third lighting source (23) is a functional panel light source that can switch between uniform lighting and striped lighting, and can be set to illuminate a specific area or the whole area.

8. The system for locating and measuring defects in glass blocks as described in claim 4, characterized in that, The third lighting source (23) includes two panel light sources, one of which emits light uniformly and the other emits light in stripes.

Images