CN107764841B - Device and method for detecting and distinguishing defects of upper surface and lower surface of transparent glass cover plate - Google Patents
Device and method for detecting and distinguishing defects of upper surface and lower surface of transparent glass cover plate Download PDFInfo
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- 239000011521 glass Substances 0.000 title claims abstract description 167
- 230000007547 defect Effects 0.000 title claims abstract description 106
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- 239000002344 surface layer Substances 0.000 claims description 36
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- 238000009434 installation Methods 0.000 claims description 6
- 238000007689 inspection Methods 0.000 claims description 4
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Abstract
The invention discloses a device and a method for detecting and distinguishing defects on the upper surface and the lower surface of a transparent glass cover plate, wherein the detection device comprises an imaging camera arranged on the transparent glass cover plate to be detected, and the imaging camera is aligned to the transparent glass cover plate to be detected through an optical lens to realize the detection of the surface defects; the depth of field range of the optical lens is far smaller than the thickness of the transparent glass cover plate to be detected, the optical axis of the optical lens is strictly vertical to the plane of the transparent glass cover plate to be detected, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lens; the fluctuation distance of the whole transparent glass cover plate to be measured at the focal length position of the optical lens is less than 1/4 of the depth of field, so that all acquired images are ensured to have good and consistent definition. The detection device can detect defects and positions of the transparent glass cover plate within a single view field range within 50ms, so that labor input is reduced, and detection efficiency is improved; an image of defect detection can be output.
Description
Technical Field
The invention belongs to the technical field of visual detection of defects of a transparent glass cover plate, relates to a device and a method for detecting and distinguishing the defects of the upper surface and the lower surface of the transparent glass cover plate, and particularly relates to a device and a method for identifying the defects of the transparent glass cover plate by utilizing visual detection and judging whether the defects of the transparent glass cover plate are positioned on the upper layer or the lower layer of the transparent glass cover plate by utilizing the depth of field difference of an optical lens.
Background
Currently, transparent glass covers are increasingly used in a plurality of electronic products, such as mobile phones, pad, etc., and the demand of the mobile phones is tens of millions each year. However, the existing defect detection method of the transparent glass cover plate is still in a stage of manual and macroscopic recognition, and the efficiency, the yield and the misjudgment are difficult to meet the requirements of the industry. Especially, when the foreign matters and scratches on the upper surface layer and the lower surface layer of the transparent glass cover plate are judged by human eyes, a great amount of labor is consumed, misjudgment is easy to occur, and the defects are difficult to distinguish between the upper surface layer and the lower surface layer of the transparent glass cover plate.
Disclosure of Invention
In order to solve the above-mentioned defects existing in the prior art, an object of the present invention is to provide a device for detecting and distinguishing the defects of the upper and lower surfaces of a transparent glass cover plate. The invention adopts two optical imaging cameras, an optical lens and a refraction-reflection prism to collect defects on the upper surface and the lower surface of the transparent glass cover plate, and then utilizes a computer software algorithm to realize the extraction of the defects of the transparent glass cover plate and the position judgment of the defects on the upper surface and the lower surface.
As a device and a method for detecting and distinguishing the defects of the upper surface and the lower surface of the transparent glass cover plate, the aim of the invention is realized by the following technical scheme.
The device for detecting and distinguishing the defects of the upper surface and the lower surface of the transparent glass cover plate comprises an imaging camera arranged on the transparent glass cover plate to be detected, wherein the imaging camera is aligned to the transparent glass cover plate to be detected through an optical lens to detect the surface defects; the depth of field of the optical lens is far smaller than the thickness of the transparent glass cover plate to be detected, the optical axis of the optical lens is strictly vertical to the plane of the transparent glass cover plate to be detected, the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lens, and the good and consistent definition of all positions for collecting the same image is ensured; the fluctuation distance of the whole transparent glass cover plate to be measured at the focal length position of the optical lens is smaller than 1/4 of the depth of field, so that all acquired images are ensured to have good and consistent definition.
Preferably, the imaging cameras arranged on the transparent glass cover plate to be tested are arranged above the upper surface of the transparent glass cover plate to be tested, two imaging cameras are arranged, outgoing beams of the two imaging cameras are converged on the catadioptric prism, an optical lens is arranged below the catadioptric prism, and the optical lens is correspondingly arranged on the upper surface of the transparent glass cover plate to be tested. The rear intercept of the imaging light path is adjusted, so that the imaging object distance difference of the two cameras is the thickness of the glass plate to be measured, the distance between the transparent glass cover plate to be measured and the lens is adjusted, and the two cameras are ensured to respectively and clearly image the upper surface layer and the lower surface layer of the transparent glass cover plate to be measured.
Preferably, the imaging cameras arranged on the transparent glass cover plate to be measured are respectively arranged on the upper surface and the lower surface of the transparent glass cover plate to be measured, and outgoing beams of the imaging camera lenses are respectively arranged corresponding to the upper surface and the lower surface of the transparent glass cover plate to be measured through the optical lenses.
Preferably, the detecting device can be fixed at a certain position, the transparent glass cover plate to be detected is installed on a moving module, or the transparent glass cover plate to be detected is installed at a certain fixed position, and the detecting device is installed on a moving module so as to image defects on the upper surface and the lower surface of the transparent glass cover plate to be detected greatly.
Correspondingly, the invention provides a detection method of a device for detecting and distinguishing the defects of the upper surface and the lower surface of a transparent glass cover plate, which comprises the following steps:
1) And (3) camera installation: the detection device is installed, the optical lens is aligned with the transparent glass cover plate to be detected vertically, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lens;
2) And (3) starting a camera: the two imaging cameras are respectively connected to the computer, the industrial personal computer and the two imaging cameras are started, and the fluctuation distance of the whole transparent glass cover plate to be tested at the focal length position of the optical lens is smaller than 1/4 of the depth of field;
3) Rear intercept adjustment: the rear intercept of imaging light paths of the two cameras are respectively adjusted, so that the imaging object distance difference of the two cameras is equal to the thickness of the glass plate to be detected, and the two cameras are respectively ensured to respectively and clearly image the upper surface layer and the lower surface layer of the transparent glass cover plate to be detected;
4) And (3) threshold calibration:
(a) The two imaging cameras collect images of the upper surface and the lower surface of the transparent glass cover plate with various defects at the same time;
(b) For each image, a gray gradient vector of any position (x, y) of the image is calculated
(c) According to defects in the cover plate of transparent glassType, threshold T of gray gradient amplitude K of corresponding defect is marked min ，T max ]Is defined by the range of (2);
5) Scanning imaging: the two imaging cameras scan the upper and lower surfaces of the transparent glass cover plate to be detected at the same time;
6) Image binarization:
(a) For each image, a gray gradient vector of any position (x, y) of the image is calculated
(b) Calculating an image gray gradient amplitude K at any image position (x, y);
(c) According to the obtained defect gray gradient threshold range, if K (x, y) epsilon T, the image gray is set to 255, the pixel is displayed as white, ifThe image gray is set to 0 and the pixel appears black:
7) Defect identification: if the gray level of a certain position of the image is white, the transparent glass cover plate to be tested has a defect at the position;
8) Positioning upper and lower layers of defects: the camera I clearly images the upper surface layer of the transparent glass cover plate to be detected, and if the image acquired by the camera I has a defect, the defect is positioned on the upper surface layer of the transparent glass cover plate to be detected; and the camera II clearly images the lower surface layer of the transparent glass cover plate to be tested, and if the image acquired by the camera II has defects, the defects are positioned on the lower surface layer of the transparent glass cover plate to be tested.
The invention also provides a detection method of the device for detecting and distinguishing the defects of the upper surface and the lower surface of the transparent glass cover plate, which comprises the following steps:
1) And (3) camera installation: two imaging devices (imaging cameras and optical lenses) are respectively arranged above and below the transparent glass cover plate to be detected, the optical lenses are aligned to the transparent glass cover plate to be detected vertically, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lenses;
2) And (3) starting a camera: the two imaging cameras are respectively connected to the computer, the industrial personal computer and the two imaging cameras are started, and the fluctuation distance of the whole transparent glass cover plate to be tested at the focal length position of the optical lens is smaller than 1/4 of the depth of field;
3) Adjusting the object distance of a camera: one imaging camera clearly images the upper surface of the transparent glass cover plate to be detected through the optical lens, and the other imaging camera clearly images the lower surface of the transparent glass cover plate to be detected through the optical lens;
4) And (3) threshold calibration:
(a) The two imaging cameras collect images of the upper surface and the lower surface of the transparent glass cover plate with various defects at the same time;
(b) For each image, calculating a calibration gray gradient vector of any position (x, y) of the image
(c) According to the type of defect on transparent glass cover plate, calibrating threshold value T of calibrated gray gradient amplitude K correspondent to defect min ，T max ]Is defined by the range of (2);
5) Scanning imaging: the two imaging cameras scan the upper and lower surfaces of the transparent glass cover plate to be detected at the same time;
6) Image binarization:
(a) For each image, calculating the actual measurement gray gradient vector of any position (x, y) of the image
(b) Calculating the actually measured gray gradient amplitude K of the image at any image position (x, y);
(c) According to the obtained defect gray gradient threshold range, if K (x, y) epsilon T, the image gray is set to 255, the pixel is displayed as white, ifThe image gray is set to 0 and the pixel is displayed as black;
7) Defect identification: if the gray level of a certain position of the image is white, the transparent glass cover plate to be tested has a defect at the position;
8) Positioning upper and lower layers of defects: the camera I clearly images the upper surface layer of the transparent glass cover plate to be detected, and if the image acquired by the camera I has a defect, the defect is positioned on the upper surface layer of the transparent glass cover plate to be detected; and the camera II clearly images the lower surface layer of the transparent glass cover plate to be tested, and if the image acquired by the camera II has defects, the defects are positioned on the lower surface layer of the transparent glass cover plate to be tested.
The beneficial effects of the invention are as follows:
1. the detection device can be used for detecting defects and positions of the transparent glass cover plate within a single view field range within 50ms, so that the input of manpower is reduced, and the detection efficiency is improved;
2. the defect detected image can be output for later inspection.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of an apparatus for detecting and distinguishing defects on upper and lower surfaces of a transparent glass cover plate;
FIG. 2 is a schematic structural view of another embodiment of an apparatus for detecting and distinguishing defects on the upper and lower surfaces of a transparent glass cover plate.
In the figure: 1 is an imaging camera I,2 is an imaging camera II,3 is a refractive prism, 4 is an optical lens, 5 is a transparent glass cover plate to be tested, 5-1 is the upper surface of the transparent glass cover plate, 5-2 is the lower surface of the transparent glass cover plate, 6 is the optical lens I, and 7 is the optical lens II.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples, which are not intended to be limiting.
As shown in fig. 1, an embodiment of the device for detecting and distinguishing defects on the upper and lower surfaces of a transparent glass cover plate is provided, wherein the core components include two imaging cameras I1 and II2 for imaging defects on the upper and lower surfaces of the transparent glass cover plate, a refractive prism 3, and an optical lens 4. The imaging camera I1 and the imaging camera II2 are mounted at the transmitting end and the reflecting end (i.e., right above and left side of the catadioptric prism) of the catadioptric prism 3, respectively. The optical lens 4 is arranged right below the catadioptric prism 3, the transparent glass cover plate 5 to be detected is positioned right below the optical lens 4, and defects and positions of the upper surface 5-1 and the lower surface 5-2 of the transparent glass cover plate 5 to be detected are detected through the detection device. Wherein, the depth of field range of the optical lens 4 is far smaller than the thickness of the transparent glass cover plate 5 to be measured; the optical axis of the optical lens 4 is strictly vertical to the plane of the transparent glass cover plate 5 to be detected, the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate 5 to be detected and the CCD of the imaging camera I1 is lower than 1/5 of the depth of field of the optical lens 4, and the good and consistent definition of all positions for collecting the same image is ensured; the fluctuation distance of the whole transparent glass cover plate 5 to be detected at the focal length position of the optical lens 4 is smaller than 1/4 of the depth of field, so that all acquired images are ensured to have good and consistent definition.
The imaging camera is used for collecting images of defects of the transparent glass cover plate, and the catadioptric prism is used for enabling two paths of detection light paths to enter the optical lens, so that the defect imaging of the transparent glass cover plate is completed.
During detection, the detection device can be fixed at a certain position, the transparent glass cover plate to be detected is installed on a motion module, or the transparent glass cover plate to be detected is installed at a certain fixed position, and the detection device is installed on a motion module so as to image defects on the upper surface and the lower surface of the transparent glass cover plate to be detected greatly.
The scheme detection steps are as follows:
1) And (3) camera installation: the detection device is installed, the optical lens is aligned with the transparent glass cover plate to be detected vertically, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lens;
2) And (3) starting a camera: the two imaging cameras are respectively connected to the computer, the industrial personal computer and the two imaging cameras are started, and the fluctuation distance of the whole transparent glass cover plate to be tested at the focal length position of the optical lens is smaller than 1/4 of the depth of field;
3) Rear intercept adjustment: the rear intercept of imaging light paths of the two cameras are respectively adjusted, so that the imaging object distance difference of the two cameras is equal to the thickness of the glass plate to be detected, and the two cameras are respectively ensured to respectively and clearly image the upper surface layer and the lower surface layer of the transparent glass cover plate to be detected;
4) And (3) threshold calibration:
(a) The two imaging cameras collect images of the upper surface and the lower surface of the transparent glass cover plate with various defects at the same time;
(b) For each image, calculating a calibration gray gradient vector of any position (x, y) of the image
Wherein f is the gray value of the image, (x, y) is the coordinate position of the image, g bx Calibration gray scale gradient in x direction g by Calibrated gray scale gradient for y-direction:
(c) According to the type of defect on transparent glass cover plate, calibrating threshold value T of calibrated gray gradient amplitude K correspondent to defect min ，T max ]Is defined in the following range:
5) Scanning imaging: the two imaging cameras scan the upper and lower surfaces of the transparent glass cover plate to be detected at the same time;
6) Image binarization:
(a) For each image, calculating the actual measurement gray gradient vector of any position (x, y) of the image
Wherein F is the gray value of the image, and (x, y) is the coordinate position of the image, g sx Is the actual measurement gray gradient in the x direction, g sy The measured gray scale gradient in the y direction is:
(b) Calculating the actual measurement gray gradient amplitude K of the image at any image position (x, y):
(c) According to the obtained defect gray gradient threshold range, if K (x, y) epsilon T, the image gray is set to 255, the pixel is displayed as white, ifThe image gray is set to 0 and the pixel appears black:
7) Defect identification: if the gray level of a certain position of the image is white, the transparent glass cover plate to be tested has a defect at the position;
8) Positioning upper and lower layers of defects: the camera I1 clearly images the upper surface layer of the transparent glass cover plate to be detected, and if the image acquired by the camera I1 has a defect, the defect is positioned on the upper surface layer of the transparent glass cover plate to be detected; and the camera II2 clearly images the lower surface layer of the transparent glass cover plate to be tested, and if the image acquired by the camera II2 has a defect, the defect is positioned on the lower surface layer of the transparent glass cover plate to be tested.
Without loss of generality, as shown in fig. 2, another embodiment of the invention can realize detection without using a catadioptric prism, and two optical lenses are adopted, an imaging camera I is provided with an optical lens I6 which is arranged right above the upper surface 5-1 of the transparent glass cover plate, images the upper surface 5-1 of the transparent glass cover plate, and an imaging camera II is provided with an optical lens II7 which is arranged right below the lower surface 5-2 of the transparent glass cover plate, and images the lower surface 5-2 of the transparent glass cover plate. Firstly, adjusting the rear intercept of an imaging camera I1 and an imaging camera II2 to enable the imaging camera I1 to image the upper surface 5-1 of the transparent glass cover plate, enabling the imaging camera II2 to image the lower surface 5-2 of the transparent glass cover plate, respectively collecting images of the upper surface 5-1 and the lower surface 5-2 of the transparent glass cover plate, calculating the change threshold value of the boundary gray level of the defect in the images by using a computer software algorithm, and determining that the defect is a defect at the position of the upper surface 5-1 (the lower surface 5-2) of the transparent glass cover plate if a certain defect threshold value of the image collected by the imaging camera I1 (the imaging camera II 2) reaches a certain degree.
The implementation steps of the embodiment are as follows:
1) And (3) camera installation: two imaging devices (imaging cameras and optical lenses) are respectively arranged above and below the transparent glass cover plate, the optical lenses are aligned to the transparent glass cover plate to be measured vertically, and the distance deviation between the four right angles of the imaging area of the transparent glass cover plate to be measured and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lenses;
2) And (3) starting a camera: the two imaging cameras are respectively connected to the computer, the industrial personal computer and the two imaging cameras are started, and the fluctuation distance of the whole transparent glass cover plate to be tested at the focal length position of the optical lens is smaller than 1/4 of the depth of field;
3) Adjusting the object distance of a camera: one of the imaging cameras clearly images the upper surface of the transparent glass cover plate through the optical lens, and the other imaging camera clearly images the lower surface of the transparent glass cover plate through the optical lens;
4) And (3) threshold calibration:
(a) The two imaging cameras collect images of the upper surface and the lower surface of the transparent glass cover plate with various defects at the same time;
(b) For each image, calculating a calibration gray gradient vector of any position (x, y) of the image
Wherein f is the gray value of the image, (x, y) is the coordinate position of the image, g bx Calibration gray scale gradient in x direction g by Calibrated gray scale gradient for y-direction:
(c) According to the type of defect on transparent glass cover plate, calibrating threshold value T of calibrated gray gradient amplitude K correspondent to defect min ，T max ]Is defined in the following range:
5) Scanning imaging: the two imaging cameras scan the upper and lower surfaces of the transparent glass cover plate to be detected at the same time;
6) Image binarization:
(a) For each image, calculating the actual measurement gray gradient vector of any position (x, y) of the image
-wherein the composition comprises,f is the gray value of the image, (x, y) is the coordinate position of the image, g sx Is the actual measurement gray gradient in the x direction, g sy The measured gray scale gradient in the y direction is:
(b) Calculating the actual measurement gray gradient amplitude K of the image at any image position (x, y):
(c) According to the obtained defect gray gradient threshold range, if K (x, y) epsilon T, the image gray is set to 255, the pixel is displayed as white, ifThe image gray is set to 0 and the pixel appears black:
7) Defect identification: if the gray level of a certain position of the image is white, the transparent glass cover plate to be tested has a defect at the position;
8) Positioning upper and lower layers of defects: the camera I1 clearly images the upper surface layer of the transparent glass cover plate to be detected, and if the image acquired by the camera I1 has a defect, the defect is positioned on the upper surface layer of the transparent glass cover plate to be detected; and the camera II2 clearly images the lower surface layer of the transparent glass cover plate to be tested, and if the image acquired by the camera II2 has a defect, the defect is positioned on the lower surface layer of the transparent glass cover plate to be tested.
The invention is not limited to the above embodiments, and based on the technical solution disclosed in the invention, a person skilled in the art may make some substitutions and modifications to some technical features thereof without creative effort according to the technical content disclosed, and all the substitutions and modifications are within the protection scope of the invention.
Claims (3)
1. The detection method for detecting and distinguishing the defects of the upper surface and the lower surface of the transparent glass cover plate is characterized by comprising the following steps:
1) And (3) camera installation: the detection device is installed, and comprises an imaging camera arranged on the transparent glass cover plate to be detected, and the imaging camera is aligned to the transparent glass cover plate to be detected through an optical lens to detect surface defects; the depth of field range of the optical lens is far smaller than the thickness of the transparent glass cover plate to be detected, the optical axis of the optical lens is strictly vertical to the plane of the transparent glass cover plate to be detected, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the imaging camera is lower than 1/5 of the depth of field of the optical lens;
the imaging cameras arranged on the transparent glass cover plate to be tested are arranged above the upper surface of the transparent glass cover plate to be tested, two imaging cameras are arranged, outgoing beams of the two imaging cameras are converged on the catadioptric prism, an optical lens is arranged below the catadioptric prism, and the optical lens is correspondingly arranged on the upper surface of the transparent glass cover plate to be tested;
the camera I clearly images the upper surface layer of the transparent glass cover plate to be detected, and the camera II clearly images the lower surface layer of the transparent glass cover plate to be detected;
2) And (3) starting a camera: the two imaging cameras are respectively connected to the computer, the industrial personal computer and the two imaging cameras are started, and the fluctuation distance of the whole transparent glass cover plate to be tested at the focal length position of the optical lens is smaller than 1/4 of the depth of field;
3) Rear intercept adjustment: the rear intercept of imaging light paths of the two cameras are respectively adjusted, so that the imaging object distance difference of the two cameras is equal to the thickness of the glass plate to be detected, and the two cameras are respectively ensured to respectively and clearly image the upper surface layer and the lower surface layer of the transparent glass cover plate to be detected;
4) And (3) threshold calibration:
(a) The two imaging cameras collect images of the upper surface and the lower surface of the transparent glass cover plate with various defects at the same time;
(b) For each image, calculating any position of the imagex，y) Is a calibrated gray gradient vector of (1)∇f；
(c) According to the type of the defect on the transparent glass cover plate to be detected, calibrating the gray gradient amplitude of the corresponding defectKThreshold range of (2)T [T min ，T max ]；
5) Scanning imaging: the two imaging cameras scan the upper and lower surfaces of the transparent glass cover plate to be detected at the same time;
6) Image binarization:
(a) For each image, calculating any position of the imagex，y) Is the actual gray gradient vector of (2)∇F；
(b) Calculating the position of any imagex，y) Actually measuring gray gradient amplitude K by the image;
(c) Based on the obtained defect gray gradient threshold range, ifThe gray level of the image is set to 255, the pixel is displayed as white, if +.>Then the image gray is set to 0 and the pixel is displayed as black:
7) Defect identification: if the gray level of a certain position of the image is white, the transparent glass cover plate to be tested has a defect at the position;
8) Positioning upper and lower layers of defects: if the image acquired by the camera I has a defect, the defect is positioned on the upper surface layer of the transparent glass cover plate to be detected; if the image acquired by the camera II has a defect, the defect is positioned on the lower surface layer of the transparent glass cover plate to be detected;
wherein, calculating any position of the imagex，y) Gray gradient vector of (a)∇fThe formula is as follows:
wherein,fis the gray value of the imagex，y) For the coordinate position of the image,g x is thatxThe amount of gray scale gradient of the direction,g y is thatyThe gray gradient of the direction is:
；
gray gradient amplitudeKCalculated by the following formula:
。
2. the detection method for detecting and distinguishing the defects of the upper surface and the lower surface of the transparent glass cover plate is characterized by comprising the following steps:
1) And (3) camera installation: the detection device is installed, and comprises an imaging camera which is aligned with the transparent glass cover plate to be detected through an optical lens to detect surface defects; the depth of field range of the optical lens is far smaller than the thickness of the transparent glass cover plate to be detected, the optical axis of the optical lens is strictly vertical to the plane of the transparent glass cover plate to be detected, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be detected and the imaging camera is lower than 1/5 of the depth of field of the optical lens;
the imaging cameras are respectively arranged above and below the transparent glass cover plate to be detected, and each imaging camera is respectively arranged corresponding to the upper surface and the lower surface of the transparent glass cover plate to be detected;
the camera I clearly images the upper surface layer of the transparent glass cover plate to be detected, and the camera II clearly images the lower surface layer of the transparent glass cover plate to be detected;
the optical lens is aligned with the transparent glass cover plate to be measured vertically, and the deviation of the distances between the four right angles of the imaging area of the transparent glass cover plate to be measured and the CCD of the imaging camera is lower than 1/5 of the depth of field of the optical lens;
2) And (3) starting a camera: the two imaging cameras are respectively connected to the computer, the industrial personal computer and the two imaging cameras are started, and the fluctuation distance of the whole transparent glass cover plate to be tested at the focal length position of the optical lens is smaller than 1/4 of the depth of field;
3) Adjusting the object distance of a camera: one imaging camera clearly images the upper surface of the transparent glass cover plate to be detected through the optical lens, and the other imaging camera clearly images the lower surface of the transparent glass cover plate to be detected through the optical lens;
4) And (3) threshold calibration:
(a) The two imaging cameras collect images of the upper surface and the lower surface of the transparent glass cover plate with various defects at the same time;
(b) For each image, calculating any position of the imagex，y) Is a calibrated gray gradient vector of (1)∇f；
(c) According to the type of the defect on the transparent glass cover plate to be detected, calibrating a threshold range of a calibrated gray gradient amplitude K corresponding to the defectT [T min ，T max ]；
5) Scanning imaging: the two imaging cameras scan the upper and lower surfaces of the transparent glass cover plate to be detected at the same time;
6) Image binarization:
(a) For each image, calculating any position of the imagex，y) Is the actual gray gradient vector of (2)∇F；
(b) Calculating the position of any imagex，y) Actually measuring gray gradient amplitude K by the image;
(c) Based on the obtained defect gray gradient threshold range, ifThe gray level of the image is set to 255, the pixel is displayed as white, if +.>Then the image gray is set to 0 and the pixel is displayed as black:
7) Defect identification: if the gray level of a certain position of the image is white, the transparent glass cover plate to be tested has a defect at the position;
8) Positioning upper and lower layers of defects: if the image acquired by the camera I has a defect, the defect is positioned on the upper surface layer of the transparent glass cover plate to be detected; if the image acquired by the camera II has a defect, the defect is positioned on the lower surface layer of the transparent glass cover plate to be detected;
wherein, calculating any position of the imagex，y) Gray gradient vector of (a)∇fThe formula is as follows:
wherein,fis the gray value of the imagex，y) For the coordinate position of the image,g x is thatxThe amount of gray scale gradient of the direction,g y is thatyThe gray gradient of the direction is:
；
gray gradient amplitudeKCalculated by the following formula:
。
3. the inspection method according to claim 1 or 2, wherein the inspection device is fixed at a certain position, the transparent glass cover plate to be inspected is mounted on a moving module, or the transparent glass cover plate to be inspected is mounted at a certain fixed position, and the inspection device is mounted on a moving module to image defects of upper and lower surfaces of the transparent glass cover plate to be inspected substantially.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711148093.2A CN107764841B (en) | 2017-11-17 | 2017-11-17 | Device and method for detecting and distinguishing defects of upper surface and lower surface of transparent glass cover plate |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711148093.2A CN107764841B (en) | 2017-11-17 | 2017-11-17 | Device and method for detecting and distinguishing defects of upper surface and lower surface of transparent glass cover plate |
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| Publication Number | Publication Date |
|---|---|
| CN107764841A CN107764841A (en) | 2018-03-06 |
| CN107764841B true CN107764841B (en) | 2024-03-01 |
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| CN108362713A (en) * | 2018-05-11 | 2018-08-03 | 中科慧远视觉技术（洛阳）有限公司 | A kind of optical detection imaging system |
| CN109682329B (en) * | 2019-02-27 | 2020-12-22 | Oppo广东移动通信有限公司 | Cover plate flatness detection method and device, detection equipment and storage medium |
| CN110658206A (en) * | 2019-09-09 | 2020-01-07 | 武汉精立电子技术有限公司 | Panel defect layered detection device and method |
| CN113655063A (en) * | 2021-08-09 | 2021-11-16 | 天津城建大学 | Detection apparatus for combined material finished product spare hole quality |
| CN114354629A (en) * | 2022-01-07 | 2022-04-15 | 苏州维嘉科技股份有限公司 | Detection equipment |
| CN114088740B (en) * | 2022-01-24 | 2022-04-29 | 武汉精立电子技术有限公司 | Method and system for determining layer of surface defect of transparent body |
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