A polarizer appearance defect detection system

Abstract

The present invention discloses a polarizer appearance defect detection system and detection method, wherein the polarizer appearance defect detection system includes a PLC controller, a feeding station, a loading station, a conveying station, a first station detection station, a second station detection station, and a unloading station electrically connected to the PLC controller, and also includes a server, and the server is electrically connected to the PLC controller, the first station detection station, and the second station detection station. The polarizer appearance defect detection system and detection method provided by the present invention mainly performs a comprehensive detection of the polarizer from the first station detection station and the second station detection station, adopts the principle of dual-field imaging to achieve scanning and positioning of a large field of view, and then achieves high-resolution imaging of tiny defects, through the combination of a low-resolution line scan camera and a high-resolution array camera, uses a low-resolution line scan to perform large-range scanning and positioning, and uses a high-resolution array to determine defects around holes, which can achieve rapid positioning of small holes and efficient identification of defects.

Description

Technical Field

[0001] The present invention relates to the technical field of polarizer defect detection, and in particular to a polarizer appearance defect detection system. Background Art

[0002] Polarizers are widely used in liquid crystal displays. They have an important impact on the brightness, contrast, viewing angle and other optical properties of liquid crystal displays. Their visual defects (appearance defects) will directly lead to the failure of liquid crystal displays. There are many types of appearance defects in polarizers. According to the location of the defects, they can be divided into substrate defects, paste defects, protective film defects, etc. According to the appearance characteristics of the defects, they can be divided into foreign matter, scratches, creases, marks, bubbles and other defects.

[0003] At present, the research on the optical performance detection technology of polarizers is relatively concentrated, while the appearance defect detection still generally adopts manual methods, using the human eye to distinguish the appearance. The manual detection method is labor-intensive and has low detection efficiency. It is easily affected by subjective factors such as the human eye's resolution ability and fatigue. The size of some defects is far below the minimum limit of human visual resolution, so it is easy to miss the detection, which in turn affects the yield rate and completion progress, and cannot meet the requirements of mass production. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a polarizer appearance defect detection system that can ensure measurement accuracy and detection accuracy, and achieve low-cost, high-precision and stable polarizer appearance defect detection.

[0005] To achieve the above object, the present invention adopts the following contents:

[0006] A polarizer appearance defect detection system, comprising:

[0007] A feeding station, where several polarizers to be tested are manually fed into the feeding bin of the feeding station;

[0008] The feeding station is used to absorb the top polarizer in the polarizer group to be tested on the feeding station;

[0009] The conveying station receives the polarizers sucked by the loading station and transports them;

[0010] The first inspection station is used to inspect the size of polarizers being transported;

[0011] The second inspection station is used to inspect circular hole defects on polarizers being transported;

[0012] Unloading station, used to absorb polarizers from the conveying station;

[0013] It also includes a PLC controller and a server. The PLC controller is electrically connected to the feeding station, the loading station, the conveying station, the first station detection station, the second station detection station, and the unloading station respectively. The server is electrically connected to the PLC controller, the first station detection station, and the second station detection station.

[0014] Preferably, the first workstation inspection station comprises a light source and at least one line scan camera, and the light source is arranged below the line scan camera and is coaxial with a lens on the line scan camera.

[0015] Preferably, the line scan camera has a pixel size of 5472*3048 and a pixel size of 2.4 μm*2.4 μm.

[0016] Preferably, the second workstation inspection station comprises an area array camera, and the area array camera cooperates with a strip light source.

[0017] Preferably, the area array camera is an 8192-pixel area array camera, and its pixel size is 5 μm.

[0018] A detection method using a polarizer appearance defect detection system comprises the following steps:

[0019] Step 1: Manual feeding: put the polarizer group to be tested into the feeding station, so that the feeding station can automatically feed the polarizer group;

[0020] Step 2: The loading station absorbs the top polarizer of the polarizer group and places the polarizer at the starting position of the conveying station;

[0021] Step 3: The conveying station starts conveying, so that the polarizer on the conveying station passes through the first inspection station and the second inspection station in sequence, and then the polarizer moves to the end position of the conveying station;

[0022] Step 4: The unloading station absorbs the polarizer that has moved to the end position of the conveying station and puts the polarizer into the corresponding tray storage box.

[0023] Preferably, in step 3, the line scan camera on the first inspection station and the area array camera on the second inspection station take pictures of the surface of the passing polarizer and transmit the test images to the server, which performs calculations on the image data.

[0024] Preferably, the server feeds back the detection result to the PLC controller, and the PLC controller controls the unloading station in step 4 to put the polarizer into the corresponding tray storage box for classified storage according to the feedback result.

[0025] Preferably, if no appearance defects of the polarizer are found in the inspection results of the server, the PLC controller controls the unloading station to place the polarizer into an OK tray storage box according to the good inspection results; if appearance defects of the polarizer are found in the inspection results of the server, the PLC controller controls the unloading station to place the polarizer into an NG tray storage box according to the bad inspection results.

[0026] The beneficial effects of the present invention are as follows: through a polarizer appearance inspection system and inspection method, the polarizer is comprehensively inspected mainly from a first inspection station and a second inspection station, and the principle of dual-field imaging is adopted to realize scanning and positioning of a large field of view, thereby realizing high-resolution imaging of tiny defects. Through the combination of a low-resolution line scan camera and a high-resolution area array camera, a low-resolution line scan is used for large-range scanning and positioning, and a high-resolution area array is used to determine defects around the hole, thereby realizing rapid positioning of the small hole and efficient identification of defects. The technical solution of combining low-resolution line scan and high-resolution area array imaging can realize both the measurement of polarizer size and the detection of polarizer appearance defects, thereby ensuring the measurement accuracy and detection accuracy, and realizing low-cost, high-precision and stable defect detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0028] Figure 1 is a system block diagram of a polarizer appearance defect detection system provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the process steps of a detection method using a polarizer appearance defect detection system provided by an embodiment of the present invention;

[0030] Figure 3 yes Figure 2 The algorithm flow chart of image processing in step 3 and step 4; DETAILED DESCRIPTION

[0031] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0032] like Figure 1 As shown, an embodiment of the present invention provides a polarizer appearance defect detection system, comprising:

[0033] A feeding station, where several polarizers to be tested are manually fed into the feeding bin of the feeding station;

[0034] The feeding station is used to absorb the top polarizer in the polarizer group to be tested on the feeding station;

[0035] The conveying station receives the polarizers sucked by the loading station and transports them;

[0036] The first inspection station is used to inspect the size of polarizers being transported;

[0037] The second inspection station is used to inspect circular hole defects on polarizers being transported;

[0038] Unloading station, used to absorb polarizers from the conveying station;

[0039] It also includes a PLC controller and a server, wherein the PLC controller is electrically connected to the feeding station, the loading station, the conveying station, the first station detection station, the second station detection station, and the unloading station, respectively, and the server is electrically connected to the PLC controller, the first station detection station, and the second station detection station, wherein:

[0040] The feeding station is the first process, which is used for receiving polarizers and manually stacking several polarizers to be tested into a polarizer group;

[0041] The loading station is the second process, which is used to absorb the polarizer on the feeding station, absorb the top polarizer of the polarizer group to be tested and move it to the next process. The loading station contains a sorting robot that can automatically absorb the polarizer and a linear module unit that drives the sorting robot to move;

[0042] The conveying station is the third process, which is used to receive the polarizers sucked by the loading station and convey the polarizers to be tested to the next process for testing. The conveying station can be a conveyor belt or other mechanism with a conveying function.

[0043] The first station inspection station is the fourth process, which is used for the size inspection of the polarizer. The first station inspection station includes a light source and at least one line scan camera. The light source is arranged below the line scan camera and is coaxial with the lens on the line scan camera. When the polarizer on the conveying station passes below the line scan camera, the line scan camera takes a photo of the polarizer and transmits the obtained image to the server.

[0044] The second inspection station is the fifth process, which is used for circular hole defect detection of polarizer. The second inspection station includes an area array camera, which is illuminated by a strip of light source. The polarizer passing through the second inspection station continues to pass under the area array camera. At this time, the area array camera takes a photo of the polarizer and transmits the obtained image to the server.

[0045] The unloading station is the last process, which is used to absorb the polarizer on the conveying station, absorb the polarizer that has completed the inspection on the conveying station, and put the polarizer into the corresponding tray storage box according to the calculation results of the server. The unloading station also includes a sorting robot that can automatically absorb the polarizer and a linear module unit that drives the sorting robot to move.

[0046] It should be noted that the optical imaging principle of the line scan camera on the first inspection station and the area array camera on the second inspection station in this embodiment is: the overall resolvable size and field of view of the optical imaging system are jointly determined by the camera and the lens, the camera's limit resolution (line pair) = 1mm / (2*pixel size), that is, Ri (line pair) = 1mm / (2*Li), the camera target surface = number of pixels * pixel size. The object resolution matched with the camera: Ro = camera's limit resolution (line pair) * lens magnification = Ri*β, the minimum resolvable size = 1 / Ro, the object field of view = camera target surface / lens magnification. In this embodiment, the line scan camera used to detect defects around the hole has a pixel number of 5472*3048, a pixel size of 2.4μm*2.4μm, a target surface of the camera h=5472*2.4μm=13.1mm, v=3048*2.4μm=7.3mm, a camera limit resolution Ri=1mm / (2*2.4μm)=208lp, and a 4X lens. Therefore, the system can distinguish the minimum size on the object side=1mm / (208*4)=0.0012mm=1.2μm, and the object field of view is H=13.1mm / 4=3.3mm, V=7.3mm / 4=1.83mm, which can meet the field of view and resolution requirements for small hole detection. In order to realize high-resolution hole crack detection, the area array camera used to detect the overall defects of the film is an 8192-pixel line scan camera with a pixel size of 5μm. The camera's maximum resolution is 1mm / (2*5μm)=100lp, the lens magnification is 0.5X, the object space resolution is 100lp*0.5=50lp, the minimum resolvable size is 1mm / 50=20μm, and the object space field of view is 8192*5μm / 0.5=81mm, which can meet the needs of fast detection of thin films with a large field of view. The two imaging systems work together to have both a large field of view and high resolution. The line scan camera is used for large-range scanning and positioning, and the high-resolution area array camera is used to determine the defects around the hole, so as to realize fast positioning of the hole and efficient identification of defects.

[0047] like Figure 2 and Figure 3As shown, an embodiment of the present invention also provides a detection method using the above-mentioned polarizer appearance defect detection system, including the following steps: Step 1: Manual loading, placing the polarizer group to be detected into the feeding station, so that the feeding station automatically feeds the polarizer group; Step 2: The loading station absorbs a polarizer on the top layer of the polarizer group, and places the polarizer to the starting position of the conveying station; Step 3: The conveying station starts to convey, so that the polarizer on the conveying station passes through the first station detection station and the second station detection station in sequence, and then the polarizer moves to the end position of the conveying station; Step 4: The unloading station absorbs the polarizer that moves to the end position of the conveying station, and places the polarizer into the corresponding material tray storage box.

[0048] Among them, in step 3, the line scan camera on the first inspection station and the area array camera on the second inspection station take pictures of the surface of the passing polarizer and transmit the test image to the server, which performs calculations on the image data. The image processing algorithm used by the server includes image binarization, image morphological operation, pixel operation, and target detection algorithm, which has great adaptability and stability and can accurately detect defects.

[0049] Specifically, the line scan camera on the first inspection station shoots the entire polarizer to be inspected three times, and obtains images of the upper, middle and lower parts of the polarizer respectively. Then, the size of the polarizer is calculated through cross-field fitting calculation, and the data is transmitted to the server; then, the polarizer to be inspected is transported to the second inspection station through the conveying station, and the area array camera on the second inspection station shoots the circular hole on the polarizer to be inspected four times, each time one-fourth of the size of the circular hole, and four pictures to be inspected are obtained respectively, and the directions of the four pictures are made consistent. Then, the circle edge coordinates of the four images are calculated by the canny edge detection algorithm, and then the positions of various defects are found by using the trained model through the deep learning algorithm and distinguished by color marking. For each defect, the corresponding defect position is found by the RGB value of each pixel on the image and its distance to the circle edge is calculated. The maximum distance on the four pictures is found and summarized, and then compared with the set standard parameters. Finally, it is determined whether it is NG or OK based on the comparison result.

[0050] The server feeds back the detection results to the PLC controller, and the PLC controller controls the unloading station in step 4 to put the polarizer into the corresponding tray storage box for classified storage according to the feedback results.

[0051] If the server's inspection results show no appearance defects in the polarizer, the PLC controller will control the unloading station to place the polarizer into the OK tray storage box based on the good inspection results; if the server's inspection results show that the polarizer has appearance defects, the PLC controller will control the unloading station to place the polarizer into the NG tray storage box based on the bad inspection results.

[0052] This method mainly conducts comprehensive inspection of the polarizer from the first inspection station and the second inspection station, adopts the principle of dual-field imaging to realize scanning and positioning of a large field of view, and then realizes high-resolution imaging of tiny defects. Through the combination of low-resolution line scan cameras and high-resolution area array cameras, low-resolution line scans are used for large-range scanning and positioning, and high-resolution area arrays are used to determine defects around the holes. Coupled with an automated system, rapid positioning of small holes and efficient identification of defects can be achieved.

[0053] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A polarizer appearance defect detection system, characterized in that: include: A feeding station, where several polarizers to be tested are manually fed into the feeding bin of the feeding station; The feeding station is used to absorb the top polarizer in the polarizer group to be tested on the feeding station; The conveying station receives the polarizers sucked by the loading station and transports them; The first station inspection station includes a light source and at least one line scan camera. The light source is arranged below the line scan camera and is coaxial with the lens on the line scan camera. The first station inspection station is used to perform size inspection on the polarizer being transported, specifically including: the line scan camera on the first station inspection station shoots the entire polarizer to be inspected three times in total, respectively obtains images of the upper, middle and lower parts of the polarizer, and then calculates the size of the polarizer through cross-page fitting calculation, and transmits the data to the server; The second station inspection station includes an area array camera, and the area array camera cooperates with a strip light source. Therefore, the second station inspection station is used to perform circular hole defect detection on the polarizer being transported, specifically including: the area array camera on the second station inspection station shoots the circular hole on the polarizer to be inspected, a total of four times, each time is one-fourth of the size of the circular hole, and four pictures to be inspected are obtained respectively, and the directions of the four pictures are made consistent, and then the circular edge coordinates of the four images are calculated by the canny edge detection algorithm, and then the positions of various defects are found by using the trained model through the deep learning algorithm and distinguished by color marking. For each defect, the corresponding defect position is found by the RGB value of each pixel point on the image and its distance to the circular edge is calculated, and the maximum distance on the four pictures is found and summarized, and then compared with the set standard parameters, and finally the NG material tray storage box or the OK material tray storage box is selected according to the comparison result; Unloading station, used to absorb polarizers from the conveying station; It also includes a PLC controller and a server. The PLC controller is electrically connected to the feeding station, the loading station, the conveying station, the first station detection station, the second station detection station, and the unloading station respectively. The server is electrically connected to the PLC controller, the first station detection station, and the second station detection station.

2. A polarizer appearance defect detection system according to claim 1, characterized in that: The pixel of the line scan camera is 5472*3048, and the pixel size is 2.4μm*2.4μm.

3. The polarizer appearance defect detection system according to claim 1, characterized in that: The area array camera is an 8192-pixel area array camera, and its pixel size is 5 μm.

4. A detection method using the polarizer appearance defect detection system according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Manual feeding: put the polarizer group to be tested into the feeding station, so that the feeding station can automatically feed the polarizer group; Step 2: The loading station absorbs the top polarizer of the polarizer group and places the polarizer at the starting position of the conveying station; Step 3: The conveying station starts conveying, so that the polarizer on the conveying station passes through the first inspection station and the second inspection station in sequence, and then the polarizer moves to the end position of the conveying station; Step 4: The unloading station absorbs the polarizer that has moved to the end position of the conveying station and puts the polarizer into the corresponding tray storage box.

5. The polarizer appearance defect detection system according to claim 4, characterized in that: In step 3, the line scan camera on the first inspection station and the area array camera on the second inspection station take pictures of the surface of the passing polarizer and transmit the test images to the server, which performs calculations on the image data.

6. The polarizer appearance defect detection system according to claim 5, characterized in that: The server feeds back the detection result to the PLC controller, and the PLC controller controls the unloading station in step 4 to put the polarizer into the corresponding tray storage box for classified storage according to the feedback result.

7. The polarizer appearance defect detection system according to claim 6, characterized in that: If the polarizer is not found to have any appearance defects in the inspection results of the server, the PLC controller controls the unloading station to place the polarizer into the OK tray storage box according to the good inspection results; if the polarizer is found to have any appearance defects in the inspection results of the server, the PLC controller controls the unloading station to place the polarizer into the NG tray storage box according to the bad inspection results.

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