System for building defect level classification models

Abstract

A method for constructing a defect level classification model for a micro LED array panel includes defining a defect classification rule for classifying pixel defects, detecting pixel defects in the micro LED array panel, identifying a pixel defect type of the detected pixel defect according to the defect classification rule, and identifying a defect level of the micro LED array panel according to the defect level classification rule and the identified pixel defect type.

Description

[Technical field]

[0001] The present disclosure relates generally to the technical field of light emitting diodes, and more particularly to a system for building a defect level classification model for a micro light emitting diode (LED) array panel. [Background technology]

[0002] With its much smaller area and higher resolution, Micro LED is becoming more and more popular around the world. Micro LED array panels can be used to form various kinds of devices, such as camera modules, light projection modules, display modules, and VR / AR light modules.

[0003] However, since the light-emitting area and image displayed by the micro LED array panel are much smaller than before, it is not easy to detect and identify pixel defects in the micro LED array panel by traditional methods, so operators need to identify pattern defects by scanning the wafer, chip, and mask through a graphical user interface that displays various patterns of the micro LED array panel.

[0004] Unfortunately, defect classification of micro LED array panels has never been done before. Due to the much smaller dimensions and space of micro LED array pixels, the concentration of pixels in a given area is much higher compared to traditional LED pixels. The defect detection process is inaccurate and time consuming.

[0005] As such, it would be advantageous to provide a method for classifying defects in micro LED arrays, enabling separation of defect types, and monitoring the classification to improve defect detection accuracy and reduce processing time.

[0006] The above contents are only used to facilitate the understanding of the technical solutions of the present application, and are not admitted to be prior art. Summary of the Invention

[0007] To overcome the above drawbacks, the present disclosure provides a method for building a defect level classification model for a micro LED array panel to improve the defect detection accuracy.

[0008] In order to achieve the above objective, the method for constructing a defect level classification model for a micro LED array panel according to the present disclosure includes: Step 01 of defining a defect classification rule for classifying pixel defects; Step 02 of detecting pixel defects in a micro LED array panel; Step 03 of identifying a pixel defect type of the detected pixel defect according to a defect classification rule; and step 04 identifying a defect level of the micro LED array panel according to the defect level classification rule and the identified pixel defect type.

[0009] In some embodiments, according to the defect classification rules, the pixel defect type includes at least a pixel point defect; Pixel defects are a dot drop having a pixel luminance below a dot drop threshold; dark pixels having a pixel luminance below a dark pixel threshold and above a dead pixel threshold; too bright pixels having a pixel luminance greater than a luminance threshold; and normal pixels having a pixel brightness between the dark pixel threshold and the brightness threshold.

[0010] In some embodiments, according to the defect classification rules, the pixel defect type further comprises a local defect; Local defects include one-dimensional defects and two-dimensional defects.

[0011] In some embodiments, the one-dimensional defects include lines of dead pixels, where the number of dead pixels is greater than a first preset number, lines of dark pixels, where the number of dark pixels is greater than a second preset number, and lines of too bright pixels, where the number of too bright pixels is greater than a third preset number.

[0012] In some embodiments, the one-dimensional defects further include a failing line of pixel point defects, the number of pixel point defects being greater than a fourth preset number.

[0013] In some embodiments, the two-dimensional defect comprises an area defect, the area defect comprising multiple pixel point defects in multiple rows or multiple columns of the micro LED pixel array.

[0014] In some embodiments, the two-dimensional defects further include defects having a point defect density in a particular region or across an entire region of a micro LED array included in the micro LED array panel.

[0015] In some embodiments, the defect classification rules include at least an overall luminance defect, which includes the following conditions: the luminance of the light emitting areas of the micro LED array panel falls below a pre-set overall luminance threshold, or the entire micro LED array panel is out of control or undriveable.

[0016] In some embodiments, the global luminance defect further comprises an out-of-control pixel.

[0017] In some embodiments, the uncontrollable pixels include always-bright pixels and un-drivable pixels.

[0018] In some embodiments, the process of detecting pixel defects in a micro LED array panel includes an overall brightness determination process and a multiple image acquisition process of acquiring multiple images.

[0019] In some embodiments, the process of detecting pixel defects in a micro LED array panel further includes a normalization process with multiple images.

[0020] In some embodiments, the process of detecting pixel defects in the micro LED array panel further includes determining whether the overall brightness of the micro LED array panel reaches or exceeds a pre-set overall brightness threshold, and if no, performing a multiple image collection process, and if yes, identifying the pixel defect type according to the pixel defect classification rule.

[0021] In some embodiments, identifying a defect level of the micro LED array panel further comprises identifying a defect level of each panel of the plurality of micro LED array panels and obtaining a defect level distribution of the plurality of micro LED array panels.

[0022] In some embodiments, according to the defect level classification rules, the defect level is: Level 1, where the micro LED array panel includes a global luminance defect or the pixel dot defect rate of the micro LED array panel is greater than a first threshold, and the pixel dot defect rate is as follows: the number of pixel dot defects / the total number of pixels; and Level 2, in which the micro LED array panel includes a first local defect or the pixel dot defect rate of the micro LED array panel is greater than a second threshold; Level 3, in which the micro LED array panel includes a second local defect or the pixel dot defect rate of the micro LED array panel exceeds a third threshold, and the characteristic value of the first local defect exceeds the characteristic value of the second local defect; and Level 4, where the pixel defect rate of the micro LED array panel exceeds the fourth threshold; and level 5, where the pixel dot defect rate of the micro LED array panel is below a fourth threshold, where the first threshold, the second threshold, the third threshold, the fourth threshold, and the fifth threshold are successively smaller.

[0023] In some embodiments, step 04 further includes including the detected pixel defect and pixel defect type of the micro LED array panel against the defect level until it is determined that one of the defect levels matches the detected pixel defect and pixel defect type.

[0024] In some embodiments, the pixel defect rate is a dead pixel rate or a ratio of dead pixels to dark pixels; The first localized defect includes at least a first point defect density in a particular region or across the entire LED array area, and the second localized defect includes at least a second point defect density in a particular region or across the entire LED array area.

[0025] In some embodiments, the first point defect density is at least four times the second point defect density.

[0026] In some embodiments, the first threshold is 50% or less, the second threshold is 1 / 50 to 1 / 10 of the first threshold, the third threshold is 1 / 20 to 1 / 10 of the second threshold, and the fourth threshold is 1 / 20 to 1 / 10 of the second threshold.

[0027] Many other advantages and features of the present disclosure will become better understood from the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0028] [Figure 1] 1 is a flowchart illustrating a method for constructing a defect level classification model for a micro LED array panel according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 illustrates a schematic list showing defect levels according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Reference will now be made in detail to the presently preferred embodiments for a better understanding of the present disclosure. The specific embodiments discussed and the accompanying drawings are merely illustrative of particular ways to make and use the disclosure and are not intended to limit the scope of the disclosure or the appended claims.

[0030] In the present disclosure, a method for detecting defects in a micro LED array panel is disclosed. The micro LED array panel is applicable in the field of displays, projectors, and scan files, etc. The micro LEDs here can be inorganic LEDs or organic LEDs. For example, the dimensions of the micro LED panel are about 5mm x 5mm. The micro LED array panel includes a micro LED array and an IC backplane formed on the back side of the micro LED array. Note that the "back side" here refers to the opposite direction of the light emission direction. The micro LED array can be any pixel matrix, such as 1600 x 1200, 680 x 480, and 1920 x 1080. The light emitting area of ​​the micro LED array panel 00 is very small, such as 3mm * 5mm. Note that the light emitting area is the area of ​​the micro LED array. The diameter of the micro LED is in the range of 200nm to 2μm. The IC backplane is formed on the back side of the micro LED array and is electrically connected with the micro LED array. The IC backplane receives signals such as image data from the outside through the signal lines to control the corresponding micro LEDs to emit light. The IC backplane generally uses an 8-bit digital-to-analog converter (DAC). The 8-bit DAC has 256 phenomenon levels, each level corresponding to one gray level, that is, the 8-bit DAC can provide 256 different gray levels. Any one of the 256 gray levels can be applied to the micro LED, so that a gray level ranging from 0 to 255 can be displayed for each pixel. Optionally, the brightness value of the micro LED can be controlled by the voltage amplitude or current amplitude of the signal received by the IC backplane, and the gray level can be indicated by the time interval, for example, the pulse width, of the signal.

[0031] Referring to FIG. 1, there is provided a method for constructing a defect level classification model for a micro LED array panel, comprising: A method is disclosed that includes step 01 of defining defect classification rules for classifying pixel defects.

[0032] Here, the defect classification rule classifies pixel defects into a number of pixel defect types, which include at least pixel point defects, which include dropped pixels having pixel brightness below a dropped pixel threshold, dark pixels having pixel brightness below a dark pixel threshold and above the dropped pixel threshold, too bright pixels having pixel brightness above a brightness threshold, and normal pixels having pixel brightness between the dark pixel threshold and the brightness threshold.

[0033] Furthermore, according to the defect classification rule, the pixel defect type further includes local defects, and the local defects include one-dimensional defects and two-dimensional defects. The one-dimensional defects include a line of dead pixels, where the number of dead pixels is greater than a first preset number, a line of dark pixels, where the number of dark pixels is greater than a second preset number, and a line of too bright pixels, where the number of too bright pixels is greater than a third preset number. The one-dimensional defects may further include a faulty line of pixel point defects, where the number of pixel point defects is greater than a fourth preset number. The two-dimensional defects include surface defects, where the surface defects include surface defects including multiple pixel point defects in multiple rows or multiple columns of the micro LED pixel array. It is noted that the first preset number, the second preset number, the third preset number, and the fourth preset number may be determined according to the actual process and are not limited herein. Furthermore, the two-dimensional defects may further include defects having a point defect density in a certain area or in the entire area of ​​the micro LED array included in the micro LED array panel.

[0034] Further, according to the defect classification rule, the pixel defect type further includes an overall brightness defect, where the overall brightness defect includes that the brightness of the light-emitting area of ​​the micro LED array panel is below a preset overall brightness threshold, or that the entire micro LED array panel is uncontrollable or undriveable, or at least one pixel is an uncontrollable pixel, where the uncontrollable pixel includes a pixel with a constant brightness and an undriveable pixel.

[0035] Step 02 detects pixel defects in the micro LED array panel.

[0036] Here, the process of detecting pixel defects of the micro LED array panel includes an overall brightness determination process and a multiple image collection process. Here, before detecting pixel defects of the micro LED array panel, the method further includes determining whether an overall brightness defect occurs in the micro LED array panel, and if "no", performing step 02 of the defect detection process. It should be noted that the overall brightness defect can be recognized by human eyes or a computer recognition system. Here, the preset overall brightness threshold may depend on the actual application and is not limited herein. If an overall brightness defect occurs in the micro LED array panel, the defect detection process of step 02 will not be performed and step 03 will be performed. Further, the overall brightness determination process includes determining whether the overall brightness of the micro LED array panel reaches or exceeds the preset overall brightness threshold, and if "no", performing a multiple image collection process, and if "yes", performing step 03 of identifying a pixel defect type according to a pixel defect classification rule.

[0037] The multiple image collection process includes collecting multiple pattern images of the micro LED array by turning on a different LED pattern each time. Here, the number of pattern images can be two or more than two. It should be noted that the LEDs in each pattern image can be turned on one or more times. In each pattern image, at least one or more LEDs are turned off between the turned on adjacent LEDs. After the image collection process, a normalization process is further performed according to the multiple images. The normalization process is understandable to those skilled in the art, and will not be described here. After collecting the multiple pattern images of the micro LED array, one or more pixel defects can be detected according to the pattern images.

[0038] Step 03: Identifying the type of pixel defect according to the defect classification rules; In step 04, the defect level of the micro LED array panel is identified according to the defect level classification rule.

[0039] Here, step 04 further includes identifying a defect level in each panel of the plurality of micro LED array panels, and then obtaining a defect level distribution of the plurality of micro LED array panels.

[0040] Referring to FIG. 2, according to the defect level classification rules, the micro LED array panel disclosed herein may have one of several possible defect levels. The defect levels include level 1, where the micro LED array panel includes a global luminance defect or the pixel dot defect rate of the micro LED array panel is above a first threshold, where the pixel dot defect rate is defined as the ratio of the number of pixel dot defects to the total number of pixels, level 2, where the micro LED array panel includes a first local defect or the pixel dot defect rate of the micro LED array panel is above a second threshold, level 3, where the micro LED array panel includes a second local defect or the pixel dot defect rate of the micro LED array panel is above a third threshold, where the characteristic value (e.g., density) of the first local defect is above the characteristic value (e.g., density) of the second local defect, level 4, where the pixel dot defect rate of the micro LED array panel is above a fourth threshold, and level 5, where the pixel dot defect rate of the micro LED array panel is below the fourth threshold, where the first threshold, the second threshold, the third threshold, and the fourth threshold are successively smaller. The pixel dot defect rate is the rate of dead dots or the ratio of dead dots to dark pixels. In this case, the rate of missing dots is equal to the number of missing dots / total number of pixels, and the ratio of missing dots to dark pixels is equal to (number of missing dots+number of dark pixels) / total number of pixels.

[0041] Identifying the defect level in the micro LED array panel further includes comparing the detected pixel defect and pixel defect type of the micro LED array panel against levels 1 to 5 until it is determined that one of levels 1 to 5 matches the detected pixel defect and pixel defect type. Preferably, the first threshold is less than or equal to 50%, preferably 20 to 30%, the second threshold is 1 / 50 to 1 / 10 of the first threshold, the third threshold is 1 / 20 to 1 / 10 of the second threshold, the third threshold is 1 / 20 to 1 / 10 of the second threshold, and the fourth threshold is 1 / 20 to 1 / 10 of the second threshold. For example, level 1 indicates that the micro LED array panel includes a global brightness defect or the pixel dot defect rate of the micro LED array panel is greater than 20%, where the pixel dot defect rate is the ratio of the number of pixel dot defects to the total number of pixels; level 2 indicates that the micro LED array panel includes a first local defect or the pixel dot defect rate of the micro LED array panel is greater than 1%; level 3 indicates that the micro LED array panel includes a second local defect or the pixel dot defect rate is greater than 0.1%; and further, at level 3, the pixel dot defect rate is 0.1% or more, or the defect density is greater than 0.4%, or the ratio of pixel dots to dark pixels is 1.2% or more, where the number of first local defects exceeds the number of second local defects; level 4 indicates that the pixel dot defect rate of the micro LED array panel is greater than 0.01%, and level 5 indicates that the pixel dot defect rate of the micro LED array panel is less than 0.01%.

[0042] It should be noted that the first localized defects include at least a first point defect density in a specific region or over the entire LED array area. The second localized defects include at least a second point defect density in a specific region or over the entire LED array area. The first point defect density is at least four times the second point defect density. Preferably, the first point defect density is at least 0.4% and the second point defect density is at least 0.1%.

[0043] Please note that if the Micro LED array panel contains any other defects except the defects mentioned above, the defect level of the Micro LED array panel will be classified as Level 3. If the Micro LED array panel contains any of the defects mentioned in the above Levels 1 to 5, the defects will be classified as the corresponding level.

[0044] The above description is merely an embodiment of the present disclosure, and the present disclosure is not limited thereto. Any modifications, equivalent replacements, and improvements made without departing from the concept and principle of the present disclosure shall be within the protection scope of the present disclosure.

Claims

1. A method for constructing a defect level classification model for a micro LED array panel, comprising: Step 01 of defining defect classification rules for classifying pixel defects; Step 02: detecting pixel defects on the micro LED array panel; 03. identifying a pixel defect type of the detected pixel defect according to the defect classification rule; 04. identifying a defect level of the micro LED array panel according to a defect level classification rule and the identified pixel defect type; A method comprising:

2. According to the defect classification rule, the pixel defect type includes at least a pixel point defect; The pixel defect is a dot drop having a pixel luminance below a dot drop threshold; dark pixels having a pixel luminance below a dark pixel threshold and above the dead pixel threshold; too bright pixels having a pixel luminance greater than a luminance threshold; a normal pixel having a pixel luminance between the dark pixel threshold and the luminance threshold; The method of claim 1 , comprising:

3. According to the defect classification rule, the pixel defect type further includes a local defect; The method of claim 2 , wherein the localized defects include one-dimensional defects and two-dimensional defects.

4. 4. The method of claim 3, wherein the one-dimensional defects include lines of dead pixels having a number of dead pixels greater than a first preset number, lines of dark pixels having a number of dark pixels greater than a second preset number, and lines of too bright pixels having a number of too bright pixels greater than a third preset number.

5. The method of claim 4 , wherein the one-dimensional defects further include a failing line of the pixel point defects, the number of the pixel point defects being greater than a fourth preset number.

6. 5. The method of claim 4, wherein the two-dimensional defect comprises an area defect, the area defect comprising a plurality of pixel point defects in a plurality of rows or a plurality of columns of a micro LED pixel array.

7. 7. The method of claim 6, wherein the two-dimensional defects further comprise defects having a point defect density in a particular region or across an entire region of a micro LED array included in the micro LED array panel.

8. 2. The method of claim 1, wherein the defect classification rules include at least an overall luminance defect, the overall luminance defect comprising the following conditions: a condition in which the luminance of a light emitting area of ​​the micro LED array panel is below a pre-set overall luminance threshold, or a condition in which the entire micro LED array panel is uncontrollable or undriveable.

9. The method of claim 8 , wherein the global luminance defect further comprises an out-of-control pixel.

10. The method of claim 9 , wherein the uncontrollable pixels include always-bright pixels and un-drivable pixels.

11. 10. The method of claim 1, wherein the process of detecting pixel defects in the micro LED array panel includes an overall brightness determination process and a multiple image acquisition process of acquiring multiple images.

12. 12. The method of claim 11, wherein the process of detecting pixel defects in the micro LED array panel further comprises a normalization process according to the multiple images.

13. 12. The method of claim 11, wherein the process of detecting pixel defects of the micro LED array panel further comprises: determining whether an overall brightness of the micro LED array panel reaches or exceeds a pre-set overall brightness threshold; if no, performing the multiple image collection process; and if yes, identifying the pixel defect type according to a pixel defect classification rule.

14. 2. The method of claim 1 , wherein identifying the defect level of the micro LED array panel further comprises: identifying a defect level of each panel of a plurality of micro LED array panels; and obtaining a defect level distribution of the plurality of micro LED array panels.

15. According to the defect level classification rules, the defect level is:

2. The method of claim 1, comprising level 1, where the micro LED array panel comprises a global luminance defect or a pixel dot defect rate of the micro LED array panel is above a first threshold, where the pixel dot defect rate is as follows: number of pixel dot defects / total number of pixels.

16. The method of claim 15 , wherein the pixel defect rate is a dead pixel rate or a ratio of dead pixels to dark pixels.

17. 16. The method of claim 15, wherein defect levels further comprise a Level 2, where the micro LED array panel includes a first localized defect or the pixel dot defect rate of the micro LED array panel is above a second threshold.

18. 20. The method of claim 17, wherein the first localized defects include at least a first point defect density in a particular area or in an entire LED array area.

19. 20. The method of claim 17, wherein defect levels further include Level 3, where the micro LED array panel includes a second local defect or the pixel dot defect rate of the micro LED array panel is above a third threshold and the characteristic value of the first local defect is above the characteristic value of the second local defect.

20. 20. The method of claim 19, wherein the second localized defects include at least a second point defect density in a particular region or in an entire LED array region.

21. 20. The method of claim 19, wherein defect levels further comprise a level 4, where the pixel dot defect rate of the micro LED array panel is above a fourth threshold.

22. 22. The method of claim 21 , further comprising: a defect level being level 5 at which the pixel dot defect rate of the micro LED array panel is below a fourth threshold, the first threshold, the second threshold, the third threshold, and the fourth threshold being successively smaller.

23. 16. The method of claim 15, wherein step 04 further comprises identifying the detected pixel defect and the pixel defect type of the micro LED array panel against a defect level until it is determined that one of the defect levels matches the detected pixel defect and the pixel defect type.

24. 20. The method of claim 19, wherein the first point defect density is at least four times the second point defect density.

25. 20. The method of claim 19, wherein the first threshold is equal to or less than 50%, the second threshold is between 1 / 50 and 1 / 10 of the first threshold, the third threshold is between 1 / 20 and 1 / 10 of the second threshold, and the fourth threshold is between 1 / 20 and 1 / 10 of the second threshold.

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