A method of inspecting a polarizing plate for black streaks

Abstract

The application discloses a method for checking black spot patterns of a polarizing plate and relates to a method for checking black spot patterns of a polarizing plate, which comprises collecting polarizing plate image data; obtaining pixel values of the image data; dividing the image data into unit regions; calculating average values of the pixel values of each unit region; and judging the unit regions based on the average values. The principle of projection reflection inspection is adopted, a local average value comparison method is used, the regions are repeatedly divided, and the unit regions without black spot patterns are removed, so that the calculation power occupation is reduced, the operation analysis speed is improved, and after only a single pixel is left in the unit region, the division is stopped. The unit regions with average values greater than a set value interval are regarded as a defective set, are circled on a gray scale diagram, and the polarizing plate with black spot patterns can be judged.

Description

Technical Field

[0001] This invention relates to the field of polarizer inspection technology, and in particular to a method for inspecting black spots on polarizers. Background Technology

[0002] A polarizing plate is a type of light-emitting diode (LED) that can extract linearly polarized light from unpolarized light and can be used as an optical attenuator, similar to an ND filter. It is approximately 100–300 μm thick and is a plywood product. The core layer is a PVA (polyvinyl alcohol) layer, which is stretched to create a polarization effect by adding halogen iodine.

[0003] Because stretching membrane materials creates an orientation angle, PVA stretching can cause local instability due to tension, temperature, and dirt removal, resulting in black spots that are barely visible and difficult to detect, leading to a high chance of missed detection. Summary of the Invention

[0004] The technical problem solved by this invention is that: due to the formation of orientation angles when stretching membrane materials, PVA will form black spots due to local instability caused by tension, temperature, and dirt cleaning during stretching. These spots are almost invisible and difficult to detect, resulting in a high probability of missed detection.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for inspecting black spots on a polarizing plate, comprising: acquiring polarizing plate image data; obtaining pixel values ​​of the image data; dividing the image data into unit regions; calculating the average value of the pixel values ​​of each unit region; and judging the unit regions based on the average value.

[0006] As a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, the acquisition of polarizing plate image data includes:

[0007] The light source and camera are positioned on opposite sides of the polarizing plate.

[0008] Irradiate one side of the polarizing plate;

[0009] The polarizing plate reflects light, creating an image on the screen.

[0010] The camera captures and displays images;

[0011] Rotate the polarizing plate;

[0012] An image is captured on the other side of the polarizing plate.

[0013] As a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, the presented image is subjected to grayscale processing to generate a grayscale image.

[0014] The grayscale image is scaled to a preset size and used as image data.

[0015] In a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, calculating the pixel values ​​of the image data includes:

[0016] Calculate the image gradient of the image data, extract the mixed pixels, and output the first pixel value array.

[0017] In a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, dividing the image data into unit regions includes:

[0018] The image data is divided into unit regions, and the set of pixels in the unit region of the first pixel value array is used as the second pixel value array.

[0019] As a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, the calculation of the average pixel value of each unit region includes:

[0020] Number each unit area;

[0021] Calculate the average difference between the pixel values ​​in the second pixel value array corresponding to each unit region.

[0022] As a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, the method for judging the unit region based on the average value includes:

[0023] Compare the average difference of pixel values ​​in the second pixel value array with a set value range;

[0024] If the average difference of pixel values ​​in the second pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding unit area;

[0025] If the average difference of pixel values ​​in the second pixel value array is within a set range, it means that there are no black spots in the corresponding unit area;

[0026] If the average difference of the pixel values ​​in all the second pixel value arrays is within the set range, it means that the polarizer does not have black spots.

[0027] As a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, the unit regions where no black spots are found are deleted;

[0028] The remaining unit regions are then divided into secondary unit regions to form secondary unit regions.

[0029] The second pixel value array is the set of pixels in the quadratic unit region, which is used as the third pixel value array.

[0030] Each secondary unit region is numbered;

[0031] Calculate the average difference of the pixel values ​​in the third pixel value array corresponding to each quadratic unit region;

[0032] If the average difference of pixel values ​​in the third pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding secondary unit area;

[0033] If the average difference of the pixel values ​​in the third pixel value array is within the set value range, it means that there are no black spots in the corresponding quadratic unit area;

[0034] Delete the secondary unit regions that do not contain black spots;

[0035] The remaining quadratic unit regions are divided into tertiary units to form tertiary unit regions; the set of pixels within each tertiary unit region is used as the fourth pixel value array.

[0036] If the average difference of pixel values ​​in the fourth pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding cubic unit area;

[0037] If the average difference of pixel values ​​in the fourth pixel value array is within a set range, it means that there are no black spots in the corresponding cubic unit area.

[0038] As a preferred embodiment of the method for inspecting black spots on a polarizing plate according to the present invention, the three-unit region is repeatedly divided four times until there is only a single pixel in the unit region.

[0039] The last segment of the cell region where the average value is greater than the set value interval is taken as the defect set and delineated on the grayscale image.

[0040] The beneficial effects of this invention are as follows: By adopting the principle of projection reflection inspection and comparing local average values, the region is repeatedly divided and the absence of black spots is eliminated, which helps to reduce computing power consumption and improve the speed of operation and analysis. The division stops when there is only a single pixel in the unit region. The unit regions with average values ​​greater than the set value are regarded as the defect set and circled on the grayscale image. This can identify polarizers with black spots and circle the black spots on the polarizers for easy manual identification. It can automatically detect defects with black spots and avoid the subsequent flow of internal defects. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the basic process of a method for inspecting black spots on a polarizing plate according to an embodiment of the present invention.

[0042] Figure 2 This is a logical diagram illustrating the detection of the location of black spots in a method for inspecting black spots on a polarizing plate, provided as an embodiment of the present invention.

[0043] Figure 3 This is a projection detection schematic diagram of a method for inspecting black spots on a polarizing plate according to an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram of the black spots in a method for inspecting black spots on a polarizing plate according to an embodiment of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0046] Example 1

[0047] Reference Figures 1 to 3 As an embodiment of the present invention, a method for inspecting black spots on a polarizing plate is provided, comprising:

[0048] S1: Acquiring polarizer image data includes:

[0049] The light source and camera are positioned on opposite sides of the polarizing plate.

[0050] Irradiate one side of the polarizing plate;

[0051] The polarizing plate reflects light, creating an image on the screen.

[0052] The camera captures and displays images;

[0053] Rotate the polarizing plate;

[0054] An image is captured on the other side of the polarizing plate.

[0055] The presented image is processed to produce a grayscale image;

[0056] The grayscale image is scaled to a preset size and used as image data.

[0057] Parallel light is preferred as the light source. By utilizing the principles of reflection and projection, the light is reflected off the surface of the polarizing plate and projected onto a white screen. At this time, the image is a magnified mirror image, avoiding optical interference such as polarization of the polarizing plate itself. The image is then captured by the camera.

[0058] S2: Obtaining the pixel values ​​of the image data includes:

[0059] Calculate the image gradient of the image data, extract the mixed pixels, and output the first pixel value array.

[0060] S3: Dividing the image data into unit regions includes:

[0061] The image data is divided into unit regions, and the set of pixels in the unit region of the first pixel value array is used as the second pixel value array.

[0062] S4: Calculating the average pixel value for each unit region includes:

[0063] Number each unit area;

[0064] Calculate the average difference between the pixel values ​​in the second pixel value array corresponding to each unit region.

[0065] S5: Based on the average value, the unit region is subjected to the following:

[0066] Compare the average difference of pixel values ​​in the second pixel value array with a set value range;

[0067] If the average difference of pixel values ​​in the second pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding unit area;

[0068] If the average difference of pixel values ​​in the second pixel value array is within a set range, it means that there are no black spots in the corresponding unit area;

[0069] If the average difference of the pixel values ​​in all the second pixel value arrays is within the set range, it means that the polarizer does not have black spots.

[0070] Delete the cell regions that do not contain black spots;

[0071] The remaining unit regions are then divided into secondary unit regions to form secondary unit regions.

[0072] The second pixel value array is the set of pixels in the quadratic unit region, which is used as the third pixel value array.

[0073] Each secondary unit region is numbered;

[0074] Calculate the average difference of the pixel values ​​in the third pixel value array corresponding to each quadratic unit region;

[0075] If the average difference of pixel values ​​in the third pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding secondary unit area;

[0076] If the average difference of the pixel values ​​in the third pixel value array is within the set value range, it means that there are no black spots in the corresponding quadratic unit area;

[0077] After deleting the secondary regions that do not have black spots, the secondary unit regions that have black spots are divided into tertiary units to form tertiary unit regions.

[0078] The set of pixels within the cubic unit region is used as the fourth pixel value array;

[0079] If the average difference of pixel values ​​in the fourth pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding cubic unit area;

[0080] If the average difference of pixel values ​​in the fourth pixel value array is within a set range, it means that there are no black spots in the corresponding cubic unit area.

[0081] The three-dimensional unit region is repeatedly divided four times to form a four-dimensional unit region;

[0082] Then compare the average difference of its pixel values ​​with the set value range, and repeat the above steps of division, calculation and comparison.

[0083] The division process stops when there is only a single pixel remaining in the unit region;

[0084] The last segment of the cell region where the average value is greater than the set value interval is taken as the defect set and delineated on the grayscale image.

[0085] The location of the defective cluster is the location of the black spots. This allows us to identify polarizers with black spots and circle the black spots on the polarizer for easy manual identification.

[0086] Employing the principle of projection reflection inspection, the method involves repeatedly dividing the region by comparing local average values ​​and eliminating areas without black spots. This reduces computational overhead and improves the speed of analysis. The division stops when only a single pixel remains within a unit area. Unit areas with average values ​​greater than a set value are considered defective and are delineated on the grayscale image. This allows for the identification of polarizers with black spots and the delineation of these spots for easy manual identification. The method automatically detects defects with black spots, preventing the re-processing of internal defects.

[0087] Example 2

[0088] Reference Figure 4 This is another embodiment of the present invention, which differs from the first embodiment in that...

[0089] In this embodiment, the 2048x128 image data is divided into 5x5 unit regions, totaling 25 unit regions, and the average difference of the pixel values ​​in the second pixel value array corresponding to each unit region is calculated.

[0090] The unit region is divided based on the average value:

[0091] Compare the average difference of pixel values ​​in the second pixel value array with a set value range;

[0092] If the average difference of pixel values ​​in the second pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding unit area;

[0093] If the average difference of pixel values ​​in the second pixel value array is within a set range, it means that there are no black spots in the corresponding unit area;

[0094] If the average difference of the pixel values ​​in all the second pixel value arrays is within the set range, it means that the polarizer does not have black spots.

[0095] Delete the cell regions that do not contain black spots;

[0096] The remaining cell regions are then further divided into 5x5 sub-regions to form secondary cell regions. Each remaining cell region also contains 25 secondary cell regions. Dividing continues until each cell region contains only a single pixel.

[0097] The last segment of the cell region where the average value is greater than the set value interval is taken as the defect set and delineated on the grayscale image.

[0098] The location of the defective cluster is the location of the black spots. This allows us to identify polarizers with black spots and circle the black spots on the polarizer for easy manual identification.

[0099] It should be recognized that embodiments of the present invention can be implemented or carried out by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable storage medium. The method can be implemented using standard programming techniques—including a non-transitory computer-readable storage medium configured with a computer program, wherein such a storage medium causes the computer to operate in a specific and predefined manner—according to the methods and drawings described in the specific embodiments. Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system. However, if desired, the program can be implemented in assembly or machine language. In any case, the language can be a compiled or interpreted language. Furthermore, for this purpose, the program can run on a programmed application-specific integrated circuit (ASIC).

[0100] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for inspecting black spots on a polarizing plate, characterized in that, include: Acquire image data of the polarizing plate; Obtain the pixel values ​​of the image data; The image data is divided into unit regions; Calculate the average pixel value for each unit region; The unit region is judged based on the average value; Judging the unit region based on the average value includes: Compare the average difference of pixel values ​​in the second pixel value array with a set value range; If the average difference of pixel values ​​in the second pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding unit area; If the average difference of pixel values ​​in the second pixel value array is within a set range, it means that there are no black spots in the corresponding unit area; If the average difference of the pixel values ​​in all the second pixel value arrays is within the set value range, it means that the polarizer does not have black spots. Delete the cell regions that do not contain black spots; The remaining unit regions are then divided into secondary unit regions to form secondary unit regions. The second pixel value array is the set of pixels in the quadratic unit region, which is used as the third pixel value array. Each secondary unit region is numbered; Calculate the average difference of the pixel values ​​in the third pixel value array corresponding to each quadratic unit region; If the average difference of pixel values ​​in the third pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding secondary unit area; If the average difference of the pixel values ​​in the third pixel value array is within the set value range, it means that there are no black spots in the corresponding quadratic unit area; Delete the secondary unit regions that do not contain black spots; The remaining secondary unit regions are divided into tertiary unit regions; The set of pixels within the cubic unit region is used as the fourth pixel value array; If the average difference of pixel values ​​in the fourth pixel value array is greater than the set value range, it indicates that there are black spots in the corresponding cubic unit area; If the average difference of the pixel values ​​in the fourth pixel value array is within the set value range, it means that there are no black spots in the corresponding cubic unit area; Repeat the process of dividing the cell region three times into four parts until there is only a single pixel in the cell region. The last segment of the cell region where the average value is greater than the set value interval is taken as the defect set and delineated on the grayscale image.

2. The method for inspecting black spots on a polarizing plate as described in claim 1, characterized in that, The acquired polarizer image data includes: The light source and camera are positioned on opposite sides of the polarizing plate. Irradiate one side of the polarizing plate; The polarizing plate reflects light, creating an image on the screen. The camera captures and displays images; Rotate the polarizing plate; An image is captured on the other side of the polarizing plate.

3. The method for inspecting black spots on a polarizing plate as described in claim 2, characterized in that: The presented image is processed to produce a grayscale image; The grayscale image is scaled to a preset size and used as image data.

4. The method for inspecting black spots on a polarizing plate as described in claim 1, characterized in that, Calculating the pixel values ​​of the image data includes: Calculate the image gradient of the image data, extract the mixed pixels, and output the first pixel value array.

5. The method for inspecting black spots on a polarizing plate as described in claim 1, characterized in that, Dividing the image data into unit regions includes: The image data is divided into unit regions, and the set of pixels in the unit region of the first pixel value array is used as the second pixel value array.

6. The method for inspecting black spots on a polarizing plate as described in claim 1, characterized in that, Calculating the average pixel value for each unit region includes: Number each unit area; Calculate the average difference between the pixel values ​​in the second pixel value array corresponding to each unit region.

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