Multi-step phase shift phase measurement method and device and storage medium

Abstract

The invention discloses a multi-step phase shift phase measurement method and device and a storage medium, which are used for improving the overall detection precision. Target precision is obtained, fringe projection quality data and environmental noise data of a phase detection system are detected, and the target precision is an error allowed in phase measurement; dynamically calculating a phase step number according to the target precision, the fringe projection quality data and the environmental noise data, and selecting a phase shift strategy according to the phase step number; acquiring a fringe interference image of the display screen to be detected; performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data; and performing defect detection according to the phase distribution data to generate defect detection data.

Description

Technical Field

[0001] The present application relates to the field of display screen defect detection, and in particular to a method, device and storage medium for multi-step phase shift phase measurement. Background Art

[0002] In the prior art, the phase deflection method is usually used to assist in display screen defect detection. The phase deflection method is a high-precision detection method based on interference fringe analysis and phase information calculation. It can detect display screen surface defects by extracting the phase gradient information of the surface of the tested display screen. One of the cores of the existing phase deflection detection method is the phase shift method, which is a high-precision phase measurement method based on fringe projection. By projecting sinusoidal fringes and collecting multiple fringe interference images with fixed phase shifts, the phase distribution of the target surface is calculated, thereby enabling the phase deflection method to be completed.

[0003] However, as the application of display screens becomes more and more extensive, more and more functions are added, and the pixel structure of the display screen becomes more and more complex, such as: the pixel spacing is getting smaller and smaller, the curvature of the flexible display screen is getting larger and larger, a thin layer of circuit area is set inside the display screen, and a display screen protective film is added during the detection process, etc., all of which make it more difficult to detect defects in the display screen. In order to improve the detection efficiency, the number of steps is usually selected in advance, but due to the gradual increase in various structures of the display screen and the detection noise of the phase detection system, the phase shift method with a fixed number of steps cannot flexibly balance the detection efficiency and detection accuracy, and cannot meet the requirements of high precision or real-time performance. Summary of the invention

[0004] The present application discloses a method, device and storage medium for multi-step phase shift phase measurement, which are used to improve overall detection accuracy.

[0005] In a first aspect, an embodiment of the present application provides a method for multi-step phase shift phase measurement, comprising: Obtain target accuracy, detect fringe projection quality data and environmental noise data of the phase detection system, where the target accuracy is the allowable error in phase measurement; dynamically calculate the number of phase steps based on the target accuracy, the fringe projection quality data and the environmental noise data, and select a phase shift strategy based on the number of phase steps; obtain a fringe interference image of the display screen to be tested; perform phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data; perform defect detection based on the phase distribution data to generate defect detection data.

[0006] Optionally, in an embodiment of the present application, after the step of acquiring the fringe interference image of the display screen to be tested, and before the step of performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data, the method further includes: optimizing the sinusoidality of the collected fringe interference image; and performing dynamic phase shift error compensation on the collected fringe interference image.

[0007] Optionally, in an embodiment of the present application, the step of optimizing the fringe sinusoidality of the collected fringe interference image includes: The light intensity distribution of the fringes in the fringe interference image is analyzed to detect non-sinusoidal errors; when non-sinusoidal errors exist, a sinusoidal optimization filter is generated; and the fringes in the fringe interference image are corrected using the sinusoidal optimization filter to generate a fringe interference image with enhanced sinusoidality.

[0008] Optionally, in an embodiment of the present application, the step of dynamically compensating the phase error of the collected fringe interference image includes: collecting the projection error and the light intensity distribution error of the phase detection system; calculating the phase error compensation amount based on the projection error and the light intensity distribution error; correcting the phase value according to the phase error compensation amount, and outputting the phase distribution after error compensation.

[0009] Optionally, in an embodiment of the present application, after the step of dynamically compensating the phase shift error of the collected fringe interference image and before the step of performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data, the method also includes: determining a thin film circuit area and a fringe area of ​​the fringe interference image; determining an overlapping area based on the thin film circuit area and the fringe area; determining a grayscale adjustment area in the overlapping area based on the fringe brightness information and the thin film circuit thickness data; and adjusting the pixel grayscale of the grayscale adjustment area on the fringe interference image based on the light intensity distribution error.

[0010] Optionally, in an embodiment of the present application, the step of obtaining a fringe interference image of the display screen to be tested includes: presetting a light source configuration, the light source is used to project sine and cosine lights of different phases; setting a reflector group, the reflector group is used to adjust the optical path; using a time-sharing stroboscopic function to project sine and cosine lights of different phases onto the display screen to be tested; and collecting the fringe interference image through a high-resolution camera and outputting it digitally.

[0011] Optionally, in an embodiment of the present application, the step of performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data includes: extracting 8 phase images from the collected fringe interference image, wherein the 8 phase images include 4 x-direction and 4 y-direction phase images; performing extraction processing and phase unwrapping processing on the 8 phase images using a corresponding phase shift method according to a phase shift strategy to generate phase distribution data.

[0012] In the second aspect, an embodiment of the present application provides a device for multi-step phase shift phase measurement, including: a first acquisition unit, used to acquire target accuracy, detect fringe projection quality data and environmental noise data of a phase detection system, where the target accuracy is the allowable error in phase measurement; a calculation unit, used to dynamically calculate the number of phase steps based on the target accuracy, fringe projection quality data and environmental noise data, and select a phase shift strategy based on the number of phase steps; a second acquisition unit, used to acquire a fringe interference image of a display screen to be tested; a first generation unit, used to perform phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data; a second generation unit, used to perform defect detection based on the phase distribution data to generate defect detection data.

[0013] Optionally, in an embodiment of the present application, after the second acquisition unit and before the first generation unit, the device also includes: an optimization unit for optimizing the sinusoidality of the collected fringe interference image; and a compensation unit for performing dynamic phase shift error compensation on the collected fringe interference image.

[0014] Optionally, in an embodiment of the present application, the optimization unit includes: analyzing the light intensity distribution of fringes in the fringe interference image and detecting non-sinusoidal errors; when non-sinusoidal errors exist, generating a sinusoidal optimization filter; using the sinusoidal optimization filter to correct the fringes in the fringe interference image to generate a fringe interference image with enhanced sinusoidality.

[0015] Optionally, in an embodiment of the present application, the compensation unit includes: collecting the projection error and light intensity distribution error of the phase detection system; calculating the phase error compensation amount according to the projection error and the light intensity distribution error; correcting the phase value according to the phase error compensation amount, and outputting the phase distribution after error compensation.

[0016] Optionally, in an embodiment of the present application, after the compensation unit and before the first generating unit, the device further includes: a first determining unit for determining a sheet circuit area and a stripe area of ​​the fringe interference image; a second determining unit for determining an overlapping area based on the sheet circuit area and the stripe area; a third determining unit for determining a grayscale adjustment area in the overlapping area based on stripe brightness information and sheet circuit thickness data; and an adjusting unit for adjusting the pixel grayscale of the grayscale adjustment area on the fringe interference image based on the light intensity distribution error.

[0017] Optionally, in an embodiment of the present application, the second acquisition unit includes: a preset light source configuration, the light source is used to project sine and cosine lights of different phases; a reflector group is set, the reflector group is used to adjust the optical path; the sine and cosine lights of different phases are projected onto the display screen to be tested using a time-sharing stroboscopic function; and the fringe interference image is collected by a high-resolution camera and output digitally.

[0018] Optionally, in an embodiment of the present application, the first generating unit includes: extracting 8 phase images from the collected fringe interference image, wherein the 8 phase images include 4 x-direction and 4 y-direction phase images; performing extraction processing and phase unwrapping processing on the 8 phase images using a corresponding phase shifting method according to a phase shifting strategy to generate phase distribution data.

[0019] In a third aspect, an embodiment of the present application provides a multi-step phase shift phase measurement device, comprising: Processor, memory, input-output unit, and bus; The processor is connected to the memory, the input and output unit, and the bus; The memory stores a program, and the processor calls the program to execute the method in the first aspect and any optional embodiment of the first aspect.

[0020] A fourth aspect of the present application provides a computer-readable storage medium, on which a program is stored. When the program is executed on a computer, the program executes the first aspect and any optional method of the first aspect.

[0021] It can be seen from the above technical solutions that this application has the following advantages: In this application, the target accuracy, fringe projection quality data and environmental noise data of the detection phase detection system are first obtained, and the target accuracy is the error allowed in the phase measurement. The number of phase steps is dynamically calculated according to the target accuracy, fringe projection quality data and environmental noise data, and the phase shift strategy is selected according to the number of phase steps. The fringe interference image of the display screen to be tested is obtained. The fringe interference image is subjected to phase extraction and phase unwrapping processing to generate phase distribution data. Defect detection is performed according to the phase distribution data to generate defect detection data.

[0022] By analyzing the fringe projection quality of the phase detection system, and then analyzing the environmental noise of the phase detection system, and calculating the number of phase steps in combination with the accuracy required by the phase detection system, a phase shift strategy is finally generated based on the calculated number of phase steps. The display screen to be tested is collected through the phase detection system and combined with the phase strategy to generate accurate phase distribution data. Finally, defects are detected through the defect detection system and accurate phase distribution data. The above method combines the accuracy of the phase detection system, fringe projection and environmental noise to generate an adaptive phase shift strategy, which improves the overall detection efficiency while increasing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 A schematic diagram of an embodiment of a method for multi-step phase shift phase measurement of the present application; Figure 2 A schematic diagram of an embodiment of the method for optimizing compensation of fringe interference images of the present application; Figure 3 A schematic diagram of an embodiment of a method for optimizing fringe sinusoidality of the present application; Figure 4 A schematic diagram of an embodiment of a method for dynamic phase error compensation of the present application; Figure 5 A schematic diagram of an embodiment of a method for adjusting a grayscale adjustment area of ​​a fringe interference image according to the present application; Figure 6 A schematic diagram of an embodiment of a method for obtaining a fringe interference image according to the present application; Figure 7 A schematic diagram of an embodiment of a method for generating phase distribution data for the present application; Figure 8 A schematic diagram of a first embodiment of a multi-step phase shift phase measurement device of the present application; Fig. 9 It is a schematic diagram of a second embodiment of the multi-step phase shift phase measurement device of the present application. DETAILED DESCRIPTION

[0025] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0026] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0027] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0029] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0030] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0031] In the prior art, the phase deflection method is usually used to assist in display screen defect detection. The phase deflection method is a high-precision detection method based on interference fringe analysis and phase information calculation. It can detect display screen surface defects by extracting the phase gradient information of the surface of the display screen under test. One of the cores of the existing phase deflection detection method is the phase shift method, which is a high-precision phase measurement method based on fringe projection. By projecting sinusoidal fringes and collecting multiple fringe interference images with fixed phase shifts, the phase distribution of the target surface is calculated, thereby enabling the phase deflection method to be completed.

[0032] However, as the application of display screens becomes more and more extensive, more and more functions are added, and the pixel structure of the display screen becomes more and more complex, such as: the pixel spacing is getting smaller and smaller, the curvature of the flexible display screen is getting larger and larger, a thin layer of circuit area is set inside the display screen, and a display screen protective film is added during the detection process, etc., all of which make it more difficult to detect defects in the display screen. In order to improve the detection efficiency, the number of steps is usually selected in advance, but due to the gradual increase in various structures of the display screen and the detection noise of the phase detection system, the phase shift method with a fixed number of steps cannot flexibly balance the detection efficiency and detection accuracy, and cannot meet the requirements of high precision or real-time performance.

[0033] Based on this, the present application discloses a method, device and storage medium for multi-step phase shift phase measurement, which are used to improve the overall detection accuracy.

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] The method of the present application can be applied to a server, a device, a terminal or other devices with logic processing capabilities, and the present application does not limit this. For the convenience of description, the following description is made by taking the execution subject as an example of a terminal.

[0036] See also Figure 1 The present application provides an embodiment of a method for multi-step phase shift phase measurement, comprising: 101. Obtain target accuracy, fringe projection quality data and environmental noise data of a detection phase detection system, wherein the target accuracy is an allowable error in phase measurement.

[0037] 102. The phase step number is dynamically calculated according to the target accuracy, fringe projection quality data and environmental noise data, and the phase shift strategy is selected according to the phase step number.

[0038] In the embodiment of the present application, the phase shift step number is dynamically adjusted through an adaptive analysis module to achieve a balance between measurement efficiency and accuracy.

[0039] Specifically, the adaptive analysis module is the front end of the entire system, responsible for dynamically calculating the phase shift steps according to the measurement environment and the target accuracy set by the user. The process takes into account the following factors: Target accuracy : Set by the user, indicating the required phase measurement error range, or a phase measurement error threshold.

[0040] Fringe projection quality :This parameter is the sine index of the fringe, which mainly reflects the optical quality of the fringe projection. This parameter is obtained by detecting the stripe data.

[0041] Environmental noise :Measure the degree of influence of environmental noise on the system, range .

[0042] Technical principle: Dynamic step calculation formula:

[0043] in, Indicates rounding up to ensure that the number of steps is an integer.

[0044] : The optimal number of steps obtained by dynamic calculation.

[0045] The main impacts include: : The higher the target accuracy ( The smaller the value, the more steps are required.

[0046] : The worse the stripe quality ( The lower the value is), the more steps are needed to compensate for the error caused by fringe distortion.

[0047] : The higher the ambient noise ( The closer it is to 1), the more steps are needed to improve robustness.

[0048] The specific implementation steps are as follows: Input measurement conditions: User inputs target accuracy , Fringe projection quality and ambient noise level .

[0049] Dynamic calculation of steps: According to the formula, substitute the relevant input parameters to calculate the optimal number of steps .

[0050] Select a phase shift strategy: if , select the three-step phase shift method or the four-step phase shift method.

[0051] if , select the multi-step method and dynamically adjust the number of steps.

[0052] 103. Obtain a fringe interference image of the display screen to be tested.

[0053] In the embodiment of the present application, the light source and acquisition device of the phase detection system are used to project stripe light onto the display screen to be tested, and then image acquisition is performed to generate a stripe schematic image. The specific acquisition method will be described in detail later.

[0054] 104. Perform phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data.

[0055] In the embodiment of the present application, the terminal needs to perform phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data that can be used for defect detection. The specific phase extraction and phase unwrapping processing will be described in the subsequent embodiments.

[0056] 105. Perform defect detection based on the phase distribution data to generate defect detection data.

[0057] In the embodiment of the present application, the terminal performs defect detection according to the phase distribution data to generate defect detection data. The specific steps are as follows: 1. Image preprocessing: Gaussian filtering can be used to smooth the image while retaining the details of the defects.

[0058]

[0059] In the formula, Represents pixel The result after Gaussian filtering is is the standard deviation.

[0060] 2. Image segmentation: The threshold segmentation algorithm is the simplest image segmentation technology, which is mainly applicable to the situation where the difference between the foreground and background is large and the area to be segmented is obvious. The key to threshold segmentation is to select a suitable threshold T to distinguish the foreground from the background. Its expression is as follows:

[0061] In the formula, represents the gray value of the pixel in the input image, T represents the threshold used to segment the foreground and background, Represents the output image.

[0062] 3. Morphological processing: Perform morphological processing on the segmented image to connect and fill small areas.

[0063] 4. Connected Domain Analysis: Use a connectivity analysis algorithm (such as depth-first search or breadth-first search) to identify and label each connected region in the binary image.

[0064] 5. Feature extraction: Calculate features for each marked blob, find the defect location, and output the results.

[0065] In the embodiment of the present application, the target accuracy is first obtained, and the fringe projection quality data and environmental noise data of the phase detection system are detected. The target accuracy is the error allowed in the phase measurement. The number of phase steps is dynamically calculated according to the target accuracy, fringe projection quality data and environmental noise data, and the phase shift strategy is selected according to the number of phase steps. The fringe interference image of the display screen to be tested is obtained. The fringe interference image is subjected to phase extraction and phase unwrapping processing to generate phase distribution data. Defect detection is performed according to the phase distribution data to generate defect detection data.

[0066] By analyzing the fringe projection quality of the phase detection system, and then analyzing the environmental noise of the phase detection system, and calculating the number of phase steps in combination with the accuracy required by the phase detection system, a phase shift strategy is finally generated based on the calculated number of phase steps. The display screen to be tested is collected through the phase detection system and combined with the phase strategy to generate accurate phase distribution data. Finally, defects are detected through the defect detection system and accurate phase distribution data. The above method combines the accuracy of the phase detection system, fringe projection and environmental noise to generate an adaptive phase shift strategy, which improves the overall detection efficiency while increasing accuracy.

[0067] See also Figure 2 The present application provides an embodiment of an optimization compensation method for a fringe interference image, comprising: 201. Optimize the fringe sinusoidality of the collected fringe interference image.

[0068] 202. Perform dynamic phase shift error compensation on the collected fringe interference image.

[0069] In the embodiment of the present application, fringe sinusoidal optimization and dynamic phase shift error compensation are performed through an optimization compensation module.

[0070] The optimization compensation module mainly optimizes and compensates the collected fringe interference image through an efficient phase shifting algorithm. Combining fringe sinusoidal optimization and dynamic phase shift error compensation, it can significantly reduce non-sinusoidal errors and phase shift errors, while improving the real-time and robustness of the system. The specific technical principles are as follows: 1. Fringe sinusoidal optimization: Enhance the fringe sinusoidal properties and reduce non-sinusoidal errors through filtering or compensation algorithms.

[0071] 2. Dynamic phase shift error compensation: Correct the phase shift deviation in real time according to the projection error and light intensity distribution error to improve the phase calculation accuracy.

[0072] The specific fringe sinusoidal optimization and dynamic phase error compensation are described in detail in subsequent embodiments.

[0073] See also Figure 3 The present application provides an embodiment of a method for optimizing fringe sinusoidality, comprising: 301. Analyze the light intensity distribution of the fringes in the fringe interference image and detect non-sinusoidal errors.

[0074] The terminal analyzes the intensity distribution of the fringes in the fringe interference image in order to detect whether there are non-sinusoidal errors that need to be processed on the fringe interference image. The main source of non-sinusoidal errors is the fringe projection system (such as gratings, laser projectors, etc.) in the phase detection system. The fringes produced by the fringe projection system may have optical distortion, causing the fringe intensity distribution to deviate from the ideal sinusoidal waveform. Non-sinusoidal errors directly affect the accuracy of phase resolution, especially in high-precision measurements, where such errors will accumulate and cause distortion of the results.

[0075] 302. When a non-sinusoidal error exists, a sinusoidal optimization filter is generated.

[0076] 303. Use a sinusoidal optimization filter to correct the fringes in the fringe interference image to generate a fringe interference image with enhanced sinusoidality.

[0077] Specifically, the stripe optimization formula in the embodiment of the present application is as follows:

[0078] : original fringe intensity; : Optimized fringe light intensity; : Sinusoidal optimized filter, specifically used to remove non-sinusoidal components.

[0079] Specific implementation steps: The terminal collects fringe data, that is, obtains the original fringe interference image. (The original fringe intensity is obtained from the image). Then, sinusoidal analysis is performed, where the terminal analyzes the intensity distribution of the fringe and detects non-sinusoidal errors. Next, filter optimization is used, where the terminal applies a sinusoidal optimization filter. The stripes are corrected. Finally, the terminal outputs the optimized stripes to generate a stripe image with enhanced sinusoidality. .

[0080] In the embodiments of the present application, the optimization of the sinusoidal properties of the stripes can significantly reduce the non-sinusoidal errors while improving the real-time performance and robustness of the system.

[0081] See also Figure 4 The present application provides an embodiment of a method for dynamic phase shift error compensation, comprising: 401. Collect projection error and light intensity distribution error of the phase detection system.

[0082] For dynamic phase shift error compensation, the source of phase shift error mainly comes from the deviation of the actual phase shift amplitude from the theoretical value caused by the instability of the light source (projection) equipment or the phase shift device. And the phase drift caused by ambient light intensity or system vibration. In the embodiment of the present application, the terminal first collects the projection error and light intensity distribution error of the phase detection system, which is used to calculate the phase shift error compensation amount based on the projection error and light intensity distribution error.

[0083] 402. Calculate a phase shift error compensation amount according to the projection error and the light intensity distribution error.

[0084] 403. Correct the phase value according to the phase shift error compensation amount, and output the phase distribution after error compensation.

[0085] In the embodiment of the present application, a phase shift error model is used to eliminate the error. The sources of the phase shift error can be divided into two parts: Projection system error : Error caused by the optical system; Intensity distribution error : Caused by uneven stripe brightness or light intensity.

[0086] Next, calculate the phase shift error compensation amount :

[0087] and is the error compensation coefficient of the projection system to the phase and the error compensation coefficient of the intensity distribution to the phase, which can be obtained by experimental calibration.

[0088] The dynamic compensation formula is as follows:

[0089] : uncorrected phase value; : Dynamically calculated phase shift error compensation; : Corrected phase value after dynamic compensation.

[0090] Specific implementation steps: 1. Error detection: collecting projection errors and light intensity distribution error ; 2. Error calculation: Calculate the phase shift error compensation using the error model ; 3. Dynamic compensation: correct the phase value and output the phase distribution after error compensation .

[0091] In the embodiments of the present application, dynamic phase error compensation can significantly reduce the phase error while improving the real-time performance and robustness of the system.

[0092] See also Figure 5 The present application provides an embodiment of a method for obtaining a fringe interference image, comprising: 501. Determine a thin-sheet circuit region and a fringe region of a fringe interference image; During the iterative update process of the display screen, the display screen has undergone many improvements in appearance and internal structure to meet more functional requirements. The improvements in the appearance of the display screen include curved screens, spliced ​​screens, and folding screens, etc. The improvements in the internal structure are mainly the addition and improvement between the internal layers of the display screen. The embodiment of the present application is mainly aimed at the structural improvement of the thin-film circuit set under the pixel layer. The improvement of this structure is different from the PCB board. The PCB printed circuit board is set under the entire display screen and provides electrical signal interaction for the entire device (including the display screen). A thin-film circuit containing metal is set under the pixel layer of the display screen, which is mainly for functional control of the pixel layer and other layers on the display screen, and the thin-film circuit is usually set in the edge area of ​​the display screen to reduce the impact on the user's observation of the display screen for picture display. However, although the thin-film circuit is designed to be very thin, there is usually a thickness range to reduce the display impact. However, for some more complex functions, the thin-film circuit will also be close to the critical thickness. At this time, the thin-film circuit can be regarded as a piece of metal thin film. This type of metal thin film has the function of light reflection and can reflect the light source of the pixel layer of the display screen to a certain extent. When the thickness of the thin-film circuit is close to the critical value, the corresponding reflectivity of the metal constituting the thin-film circuit will gradually increase. At this time, it is possible to affect the grayscale and brightness changes at the edge of the display screen (because the thin-film circuit will reflect the sine and cosine light projected by the light source twice on the basis of the first reflection of the display screen). This will affect the collection of the fringe interference image of the display screen, and will cause the sine and cosine light in the thin-film circuit area (the edge area corresponding to the thin-film circuit on the display screen) and the overlapping area of ​​the fringe area to differ, and this difference will be reflected in the fringe interference image. In addition, due to the uneven brightness or light intensity of the fringe, the thin-film circuit will further cause differences in the grayscale and brightness of the image on the fringe interference image. At this time, the fringe interference image needs to be processed to eliminate the circuit area reflection.

[0093] 502. Determine an overlapping area according to the thin circuit area and the stripe area; Specifically, in the embodiment of the present application, the terminal first determines the sheet circuit area and the stripe area of ​​the fringe interference image, and then determines the overlapping area between the sheet circuit area and the stripe area.

[0094] 503. Determine a grayscale adjustment region in the overlapping region according to the stripe brightness information and the sheet circuit thickness data; The terminal needs to obtain the corresponding stripe brightness information in the overlapping area, and then generate the corresponding reflectivity according to the sheet circuit thickness data of the overlapping area, and determine the affected overlapping area, that is, the grayscale adjustment area, through the stripe brightness information and reflectivity information.

[0095] 504. Adjust the pixel grayscale of the grayscale adjustment area on the fringe interference image according to the light intensity distribution error.

[0096] After the terminal determines the grayscale adjustment area, it can obtain the intensity distribution error caused by uneven stripe brightness or light intensity, and then perform circuit area reflection elimination processing based on the stripe brightness information and reflectivity.

[0097] The circuit area reflection elimination formula is as follows:

[0098] In this embodiment, is the intensity distribution error, is the pixel grayscale after the circuit area reflection elimination process. It is the pixel grayscale before the circuit area reflection removal process. is the reflectivity of the thin film circuit, is the error compensation coefficient of the intensity distribution to the grayscale reflection of the display screen. This parameter is obtained through experiments, mainly by using different sine and cosine lights to illuminate the display screen, and then collecting images to analyze the grayscale differences. It will not be described here. Through the above formula, the fringe interference image after the reflection elimination process in the circuit area can be obtained, providing accurate image information for subsequent defect detection, brightness detection and other links.

[0099] See also Figure 6 The present application provides an embodiment of a method for obtaining a fringe interference image, comprising: 601. The light source configuration is preset, and the light source is used to project sine and cosine lights of different phases.

[0100] In the embodiment of the present application, the terminal first sets up an optical detection module, where the optical detection module is the front end of the entire system, responsible for obtaining the fringe interference image on the surface of the object being measured through optical principles, and providing high-quality input data for subsequent image processing. The terminal first presets the light source configuration, and the light source is used to project sine and cosine lights of different phases.

[0101] 602. Set a reflector group, where the reflector group is used to adjust the light path.

[0102] Next, the terminal sets a reflector group, which is used to adjust the light path so that the interference fringes are evenly projected onto the surface of the object and optimize the reflection path of the fringes.

[0103] 603. Use the time-sharing strobe function to project sine and cosine lights of different phases onto the display screen to be tested.

[0104] Next, the terminal uses the time-sharing strobe function to project sine and cosine lights of different phases onto the display screen to be tested, so that corresponding stripes are displayed on the display screen to be tested.

[0105] 604. The fringe interference image is collected by a high-resolution camera and output digitally.

[0106] Combining the above steps, the key tasks of the optical inspection module include: 1. Preset the light source configuration so that it can project sine and cosine light of different phases. The light source should have high brightness and high uniformity to ensure the clarity of the projected stripes. Use the time-sharing strobe function to project sine and cosine light of different phases onto the product (display to be tested).

[0107] 2. Optimize the optical path design and add a reflector group. The purpose is to adjust the optical path so that the interference fringes are evenly projected onto the surface of the object and optimize the reflection path of the fringes.

[0108] a) Specifically, high-quality reflectors are needed to ensure a stable optical path and efficient use of light energy.

[0109] b) Secondly, it is also necessary to use multi-layer coated lenses, which can reduce light energy loss and improve reflection efficiency.

[0110] 3. Use a high-resolution camera to capture fringe interference images and output them digitally to provide data for subsequent phase calculations.

[0111] See also Figure 7 The present application provides an embodiment of a method for generating phase distribution data, comprising: 701. Extract 8 phase images from the collected fringe interference image, wherein the 8 phase images include 4 phase images in the x direction and 4 phase images in the y direction.

[0112] 702. Perform extraction processing and phase unwrapping processing on the eight phase images using a corresponding phase shift method according to the phase shift strategy to generate phase distribution data.

[0113] In the embodiment of the present application, an image processing module is used to perform phase extraction and phase unwrapping processing on the collected reflection fringe image. The image processing module is the core part of the entire system, which is used to process the reflection fringe image obtained by the optical detection module, extract surface morphology information and identify defects. The specific subsystems are as follows: 1. Phase calculation module: Phase calculation is the first step in image processing and is responsible for extracting the initial phase distribution from the reflected fringe image. The details are as follows: a) First, image extraction is performed. Using the time-sharing stroboscopic function and the 4-step phase shift method, 8 phase images are extracted from the collected fringe phase image, including 4 phase images in the x-direction and 4 phase images in the y-direction.

[0114] Light intensity distribution of fringe image: The light intensity distribution of interference fringe image can be expressed as:

[0115] is the pixel point in the reflected fringe image The light intensity on.

[0116] is the background light intensity.

[0117] It is the fringe modulation degree, which is related to the fringe contrast.

[0118] is the phase distribution, reflecting the surface height information.

[0119] The phase extraction method is to use the phase shift method to extract the phase. Specifically, the phase shift method requires the display to display multiple images with different initial phases and obtain them by the camera. When sinusoidal fringes are used, assuming that the N-step phase shift method is used, the light intensity expression received by the camera (image acquisition device) is:

[0120] In the formula, is the image intensity when the phase shift is n steps, which is a known quantity obtained by the camera, represents the background light intensity distribution, Indicates the modulation distribution, phase is the unknown quantity to be solved, so we need to find At least three phase shifts are required, that is, N is at least 3. The least squares method can be used to solve it, where The result is:

[0121] Since the inverse tangent function has a range of ,so is the absolute phase value folded into Wrapped phase within the interval. There are multiple grayscale cutoffs in the folded phase image. The cutoffs are aliased with the object under test and the defects, and the defects cannot be identified. Therefore, the obtained wrapped phase must be unfolded. This process is called phase unfolding.

[0122] d) Phase unwrapping: Since the phase is usually limited to the interval , there may be jumps in the phase calculation, resulting in discontinuity. Phase unpacking achieves phase continuity by removing jumps. The phase information after bit unpacking is:

[0123] Where N is an integer multiple added during the unpacking process , For phase distribution, ensure phase continuity.

[0124] See also Figure 8 The present application provides an embodiment of a multi-step phase shift phase measurement device, comprising: The first acquisition unit 801 is used to acquire target accuracy and detect fringe projection quality data and environmental noise data of the phase detection system. The target accuracy is the error allowed in phase measurement.

[0125] The calculation unit 802 is used to dynamically calculate the phase step number according to the target accuracy, the fringe projection quality data and the environmental noise data, and select the phase shift strategy according to the phase step number.

[0126] The second acquisition unit 803 is used to acquire the fringe interference image of the display screen to be tested.

[0127] Optionally, in an embodiment of the present application, the second obtaining unit 803 includes: The light source configuration is preset, and the light source is used to project sine and cosine lights of different phases.

[0128] A reflector group is provided, wherein the reflector group is used to adjust the light path.

[0129] The time-sharing strobe function is used to project sine and cosine lights of different phases onto the display screen to be tested.

[0130] The fringe interference image is collected by a high-resolution camera and output digitally.

[0131] The optimization unit 804 is used to optimize the fringe sinusoidality of the collected fringe interference image.

[0132] Optionally, in an embodiment of the present application, the optimization unit 804 includes: Analyze the light intensity distribution of the fringes in the fringe interference pattern and detect non-sinusoidal errors.

[0133] When non-sinusoidal errors are present, a sinusoidal optimized filter is generated.

[0134] The fringes in the fringe interference image are corrected using a sinusoidal optimization filter to generate a fringe interference image with enhanced sinusoidality.

[0135] The compensation unit 805 is used to perform dynamic phase shift error compensation on the collected fringe interference image.

[0136] Optionally, in an embodiment of the present application, the compensation unit 805 includes: Collect projection errors and light intensity distribution errors of phase detection systems.

[0137] The phase shift error compensation amount is calculated based on the projection error and the light intensity distribution error.

[0138] The phase value is corrected according to the phase shift error compensation amount, and the phase distribution after error compensation is output.

[0139] The first determining unit 806 is used to determine the thin-sheet circuit area and the fringe area of ​​the fringe interference image.

[0140] The second determining unit 807 is used to determine the overlapping area according to the thin circuit area and the stripe area.

[0141] The third determining unit 808 is used to determine the grayscale adjustment area in the overlapping area according to the stripe brightness information and the sheet circuit thickness data.

[0142] The adjustment unit 809 is used to adjust the pixel grayscale of the grayscale adjustment area on the fringe interference image according to the light intensity distribution error.

[0143] The first generating unit 810 is used to perform phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data.

[0144] Optionally, in an embodiment of the present application, the first generating unit 810 includes: Eight phase images are extracted from the collected fringe interference image, wherein the eight phase images include four phase images in the x direction and four phase images in the y direction.

[0145] According to the phase shift strategy, the eight phase images are extracted and phase unwrapped using the corresponding phase shift method to generate phase distribution data.

[0146] The second generating unit 811 is used to perform defect detection according to the phase distribution data and generate defect detection data.

[0147] See also Fig. 9, the present application provides a device for multi-step phase shift phase measurement, comprising: Processor 901 , memory 902 , input-output unit 903 , and bus 904 .

[0148] The processor 901 is connected to the memory 902 , the input and output unit 903 , and the bus 904 .

[0149] The memory 902 stores a program, and the processor 901 calls the program to execute the following steps: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The method in .

[0150] The present application provides a computer-readable storage medium, on which a program is stored, and when the program is executed on a computer, the program performs the following steps: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The method in .

[0151] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0152] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0153] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0154] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0155] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-only memory), random access memory (RAM, random access memory), disk or optical disk and other media that can store program code.

Claims

1. A method for multi-step phase shift phase measurement, characterized in that: include: Acquire target accuracy, detect fringe projection quality data and environmental noise data of the phase detection system, wherein the target accuracy is the allowable error in phase measurement; Dynamically calculating the number of phase steps according to the target accuracy, the fringe projection quality data and the environmental noise data, and selecting a phase shift strategy according to the number of phase steps; Acquire a fringe interference image of the display screen to be tested; Performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data; Defect detection is performed according to the phase distribution data to generate defect detection data.

2. The method according to claim 1, characterized in that After the step of acquiring the fringe interference image of the display screen to be tested and before the step of performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data, the method further includes: Optimize the fringe sinusoidality of the collected fringe interference image; Dynamic phase shift error compensation is performed on the collected fringe interference image.

3. The method according to claim 2, characterized in that The step of optimizing the fringe sinusoidality of the collected fringe interference image comprises: Analyzing the light intensity distribution of fringes in the fringe interference image to detect non-sinusoidal errors; When there are non-sinusoidal errors, a sinusoidal optimized filter is generated; The sinusoidal optimization filter is used to correct the fringes in the fringe interference image to generate a fringe interference image with enhanced sinusoidality.

4. The method according to claim 2, characterized in that: The step of performing dynamic phase shift error compensation on the collected fringe interference image comprises: Collecting projection error and light intensity distribution error of the phase detection system; Calculating a phase shift error compensation amount according to the projection error and the light intensity distribution error; The phase value is corrected according to the phase shift error compensation amount, and a phase distribution after error compensation is output.

5. The method according to claim 4, characterized in that After the step of performing dynamic phase shift error compensation on the collected fringe interference image and before the step of performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data, the method further includes: Determining a sheet circuit area and a fringe area of ​​the fringe interference image; Determining an overlapping area based on the thin film circuit area and the stripe area; Determine a grayscale adjustment region in the overlap region according to stripe brightness information and sheet circuit thickness data; The pixel grayscale of the grayscale adjustment area on the fringe interference image is adjusted according to the light intensity distribution error.

6. The method according to any one of claims 1 to 5, characterized in that The step of obtaining the fringe interference image of the display screen to be tested comprises: A light source configuration is preset, wherein the light source is used to project sine and cosine lights of different phases; Setting a reflector group, wherein the reflector group is used to adjust the light path; The time-sharing strobe function is used to project sine and cosine lights of different phases onto the display screen to be tested; The fringe interference image is collected by a high-resolution camera and output digitally.

7. The method according to any one of claims 1 to 5, characterized in that The step of performing phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data comprises: Extract 8 phase images from the collected fringe interference image, wherein the 8 phase images include 4 phase images in the x direction and 4 phase images in the y direction; According to the phase shift strategy, the eight phase images are extracted and phase unwrapped using the corresponding phase shift method to generate phase distribution data.

8. A device for multi-step phase shift phase measurement, characterized in that: include: A first acquisition unit is used to acquire target accuracy, fringe projection quality data of a detection phase detection system, and environmental noise data, wherein the target accuracy is an allowable error in phase measurement; A calculation unit, configured to dynamically calculate the number of phase steps according to the target accuracy, the fringe projection quality data and the environmental noise data, and select a phase shift strategy according to the number of phase steps; A second acquisition unit, used to acquire a fringe interference image of the display screen to be tested; A first generating unit, configured to perform phase extraction and phase unwrapping processing on the fringe interference image to generate phase distribution data; The second generating unit is used to perform defect detection according to the phase distribution data to generate defect detection data.

9. The device according to claim 8, characterized in that The device also includes: An optimization unit, used for optimizing the fringe sinusoidality of the collected fringe interference image; The compensation unit is used to perform dynamic phase shift error compensation on the collected fringe interference image.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program, and when the program is executed on a computer, the apparatus according to any one of claims 1 to 7 is executed.

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